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THE DESIGN OF A 7, 000KG PER-ANNUM LEMONGRASS OIL PRODUCTION PLANT USING STEAM DISTILLATION Presented to The Department of Chemical and Petroleum Engineering UNIVERSITY OF LAGOS In partial fulfillment of the requirements for the award of Bachelor of Science (B.Sc.) in Chemical Engineering By THE CEOs (Group 3)

MEMBERS: ROY-LAYINDE BOSUN .A.

120401074

ANONYUO ANSELEM S.

120401020

OSINOWO DAMILOLA H.

120401070

ADEJUMO SEGUN O.

120401004

TAIWO OLUGBEMIRO D.

130401071

ADEDINSEWO FRANCIS A.

130401078

USMAN JUMAI D.

130401057

MATTHEW EMEKA COLLINS

100401042

DATE SUBMITTED: 10Q-2017

CERTIFICATION This is to certify that the research project entitled “THE DESIGN OF A 7000 KG PER ANNUM LEMONGRASS OIL PRODUCTION PLANT USING STEAM DISTILLATION” is an original work conducted by THE CEOs and submitted to the Department of Chemical and Petroleum Engineering as a partial fulfilment of the requirement for the award of the degree of Bachelor of Science in Chemical Engineering, University of Lagos.

ROY-LAYINDE, BOSUN, A.

……………………………..

ANONYUO, ANSELEM S.

……………………………..

OSINOWO, OLUWADAMILOLA, H.

……………………………..

USMAN, JUMAI D.

……………………………..

ADEJUMO, OLUWASEGUN O.

……………………………..

ADEDINSEWO, FRANCIS A.

……………………………..

TAIWO, OLUGBEMIRO D.

……………………………..

MATTHEW, EMEKA C.

……………………………..

…………………………………….. Dr. Daniel Ayo Project

Co-ordinator

The CEOs, Department of Chemical Engineering, University of Lagos October, 2017

The Head, Department of Chemical Engineering, University of Lagos CC: Dr. Daniel Ayo. LETTER OF TRANSMITTAL In accordance with the regulations of the Faculty of Engineering, University of Lagos, THE CEOs (Group 3) hereby presents her design project report which includes: process route and equipment specification, mass balance, energy balance, process flow diagram, P & ID for the plant and around the distillation unit, chemical engineering design for the distillation unit, mechanical design of the distillation unit, material handling and HAZOP, plant layout, site layout and costing and evaluation over a 15 year period for the design of a 7,000kg per annum lemongrass oil production plant using steam distillation This is a partial fulfilment of the requirements for the award of Bachelor of Science degree in Chemical Engineering at the University of Lagos. Yours faithfully, ………………………………… Roy-Layinde Olatubosun Leader, The CEOs

ACKNOWLEDGEMENT This work is dedicated to the almighty God for seeing us through this design work. We would like to express our deepest appreciation and gratitude to our project coordinator, Dr. Daniel Ayo for his valuable guidance, advice, and encouragement throughout this experience.

EXECUTIVE SUMMARY An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plant. Essential oils are very important as they have wide usage in the medical world as well as the food, cosmetic and many other manufacturing industries. The aim of this project is to produce quality essential oil (lemongrass oil) that would meet the demand of consumers, to make profits and to increase foreign exchange by exporting the essential oil produce. Essential oils can be manufactured using different methods but in this project, the steam distillation method is used. This is because old-time distillers favor this method for most oils, and say that none of the newer methods produces better quality oils, and stem distillation is appropriate for temperature sensitive materials like lemongrass whose boiling point is 240oC. 7000kg of lemongrass oil are to be produced per annum using lemongrass as the main raw material. 1794kg of lemongrass is needed daily. It leaves the dryer, fed into the still tank and the distillation process is carried out leaving the spent grass in as accumulation. This vapor mixture of oil and steam is then condensed to liquid and the mixture is separated under gravity to the hydrosol and 27kg of lemon grass oil daily. This project also contains a process flow diagram showing the general arrangement of all the major equipments and general flow of materials. The plant will be located in Igbesa, Ogun state because of its proximity to target market (Lagos and Ibadan), availability large expanse of land for cultivation of lemongrass plant setup and office space including many more factors. The initial invested needed for this project is N45,000,000. The man power requirements for this project are 50 people. The total envisaged profit for the 15 year project is at least N476,000,000 sales of lemongrass oil; with a payback period of 3 years and break-even point of 3271 unit of lemongrass oil to be sold at N900 per 100g bottle. Profit will also be made from the sale of the by product (hydrosol) to skin care industries and sale of spent lemongrass to farmers.

With unsatisfied demand of lemongrass oil being 1400 tons in 2017, and this figure expected to grow to 2400 tons by 2024, there is a very large market available for this product. This project will provide job opportunities for Nigerians, will make profit, and has the capability of increasing foreign exchange by exporting. Hence this is a viable business an investor should be willing to invest in.

TABLE OF CONTENTS CERTIFICATION ................................................................................................................................ 2 LETTER OF TRANSMITTAL............................................................................................................ 3 ACKNOWLEDGEMENT ................................................................................................................... 4 EXECUTIVE SUMMARY .................................................................................................................. 5 CHAPTER ONE ................................................................................................................................ 11 1.

INTRODUCTION ...................................................................................................................... 11

1.1

AIM OF PROJECT ................................................................................................................. 12

CHAPTER TWO................................................................................................................................ 13 2.

LITERATURE REVIEW ........................................................................................................... 13

2.1

HISTORY OF ESSENTIAL OILS ......................................................................................... 13

2.2

USEFULNESS OF ESSENTIAL OILS. ................................................................................. 13

2.3

LEMON GRASS ESSENTIAL OIL ....................................................................................... 14

2.4

COMPOSITION OF LEMON GRASS ESSENTIAL OIL .................................................... 15

2.5

METHODS OF EXTRACTING ESSENTIAL OILS ............................................................. 17

2.5.1

SOLVENT EXTRACTION METHOD .............................................................................. 17

2.5.2 ENFLEURAGE ......................................................................................................................... 17 2.5.3 COLD PRESSED EXPRESSION ............................................................................................. 17 2.5.4 SUPER CRITICAL CO2 EXTRACTION: ............................................................................... 18 2.5.5

HYDRO-DISTILLATION .................................................................................................. 18

CHAPTER THREE ............................................................................................................................ 20 3.0.

PROCESS ROUTE AND EQUIPMENT SPECIFICATION ................................................. 20

3.1

PROCESS ROUTE SELECTION .......................................................................................... 20

3.2

STEAM DISTILLATION ....................................................................................................... 20

3.3

METHOD AND PROCEDURE ............................................................................................. 21

3.3.1

CUTTING............................................................................................................................ 21

3.3.2 DRYING ................................................................................................................................... 22 3.3.3

DISTILLATION .................................................................................................................. 22

3.3.4

CONDENSATION .............................................................................................................. 22

3.3.5

OIL AND WATER SEPERATION .................................................................................... 22

3.3.6

PACKAGING..................................................................................................................... 23

3.3.7

STORAGE ........................................................................................................................... 23

3.4

MODE OF OPERATION ....................................................................................................... 23

CHAPTER FOUR .............................................................................................................................. 31 4.0

MATERIAL AND ENERGY BALANCES .......................................................................... 31

4.1 MATERIAL BALANCE ............................................................................................................. 31 4.2

ENERGY BALANCE ............................................................................................................. 38

CHAPTER FIVE ................................................................................................................................ 44 5.0

PROCESS FLOW DIAGRAM .............................................................................................. 44

CHAPTER SIX .................................................................................................................................. 46 6.0

PIPING AND INSTRUMENTATION DIAGRAM ............................................................... 46

CHAPTER SEVEN ............................................................................................................................ 48 7.0

CHEMICAL ENGINEERING DESIGN OF THE MAIN PROCESS UNIT ......................... 48

7.1

INTRODUCTION ................................................................................................................... 48

7.2

MATERIAL OF CONSTRUCTION ...................................................................................... 48

7.3

CALCULATION AND ANALYSIS ...................................................................................... 49

7.4

PRESSURE DROP ................................................................................................................. 51

CHAPTER EIGHT ............................................................................................................................. 54 8.0

MECHANICAL DESIGN OF THE STILL TANK ................................................................ 54

8.1

MAXIMUM ALLOWABLE STRESS ................................................................................... 54

8.2

THICKNESS OF THE STILL TANK WALL ....................................................................... 55

8.3

CLOSURE OF THE STILL TANK ....................................................................................... 56

8.4

LOADS.................................................................................................................................... 56

8.5

TEST FOR STABILITY ......................................................................................................... 58

CHAPTER NINE ............................................................................................................................... 60 9.0

STATEMENT ON MATERIALS HANDLING .................................................................... 60

9.1

INTRODUCTION .................................................................................................................. 60

9.2

MATERIALS HANDLING WITH CONVEYOR. ................................................................ 63

9.3

STORAGE OF ESSENTIAL OIL. ......................................................................................... 64

9.4

WORK STATION DESIGN ................................................................................................... 65

CHAPTER TEN ................................................................................................................................. 66 10.0

MATERIAL SAFETY DATA SHEET .................................................................................. 66

CHAPTER ELEVEN ......................................................................................................................... 71 11.0

HAZARD AND OPERABILITY STUDIES SUMMARY (HAZOPs) .................................. 71

11.1

OVERVIEW............................................................................................................................ 71

11..2

HAZOP STUDIES ON SELECTED EQUIPMENT .......................................................... 83

CHAPTER TWELVE ........................................................................................................................ 88 12.0

SITE LAYOUT AND PLANT LAYOUT .............................................................................. 88

12.1

`SITE LAYOUT ...................................................................................................................... 88

12.2

SITE SELECTION .................................................................................................................. 89

12.3

PLANT LAYOUT................................................................................................................... 90

12.4

FACTORS CONSIDERED FOR PLANT LAYOUT ............................................................ 90

CHAPTER THIRTEEN ..................................................................................................................... 92 13.0

ECONOMIC EVALUATION OVER FIFTEEN YEAR PERIOD ........................................ 92

13.1

PLANT CAPACIITY .............................................................................................................. 92

13.2

PRODUCTION PROGRAM .................................................................................................. 92

13.3

MANPOWER REQUIREMENT ............................................................................................ 92

13.4

RAW MATERIAL PROCUREMENT ................................................................................... 95

13.5

PLANT AND MACHINERIES .............................................................................................. 97

13.7

INITIAL INVESTMENT COST ......................................................................................... 100

13.8

FULL CAPACITY PRODUCTION COST (ANNUAL) ..................................................... 100

13.9

PROJECTED REVENUE ..................................................................................................... 101

13.10

ANNUAL PROFIT ........................................................................................................... 102

13.11

BREAKEVEN POINT ...................................................................................................... 104

13.12

PAY-BACK PERIOD ....................................................................................................... 104

13.13

ECONOMIC BENEFITS .................................................................................................. 105

CHAPTER ONE 1. INTRODUCTION An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetherolea, or simply as the oil of the plant from which they were extracted. An oil is "essential" in the sense that it contains the "essence of" the plant's fragrance— the characteristic fragrance of the plant from which it is derived. Natural essential oils are volatile, fragrant and pleasant tasting oils obtained from leaves, roots, flowers and fruits. They have wide applications in pharmaceutical, foods, perfumery and cosmetics.

A variety of plants have a high content of essential oils that are feasible for

commercial production. These plants mature fast, requiring little maintenance. The extraction of oil from these varieties poses no special problems and the end product is marketable both locally and abroad.

The origin of essential oil can be traced to an ancient concept – essential quintessence. About 300 essential oils have been identified, though only about 150 have been exploited for commercial purposes of production. According to Menair, out of 225 plant families only 29.5% are in tropical as well as temperate climate regions and 28% in all climates. Essential oils come from the flowers (rose), fruits, leaves (lemon grass), roots (valerian), seeds (Nutmeg oil), and bark (Cinnamon) of many plants. Oil of lavender, for example, is derived from a flower, oil of patchouli from a leaf, and oil of orange from a fruit. The oils are formed in the green (chlorophyll-bearing) parts of the plant, and with plant maturity are transported to other tissues, particularly to the flowering shoots. The exact function of an essential oil in a plant is unknown; it may be to attract insects for pollination, or to repel harmful insects, or it may be simply a metabolic intermediate.

There are various methods which could be used for the extraction of essential oils from plant. The method used in extraction of oil from its plants depends on the type of botanical material that makes up the plant and also, the method of extraction affects the quality of oil being extracted. Some methods used in the extraction of essential oils from plants include: 1. Distillation; Water distillation, steam distillation, and water and steam distillation 2. Expression; Sponge expression, and machine abrasion. 3.

Solvent extraction; Maceration, Enfleurage, supercritical extraction.

Currently the most popular method of extraction is steam distillation, but as technological advances are made, more efficient and economical methods are being developed. These include methods such as solvent extraction, supercritical fluid extraction, cold pressing, and microwave extraction (Kabuba & Robert, 2009). The suitability of extraction method varies from plant to plant and there are significant differences in the capital and operational costs associated (Sheridan, 2000).

1.1

AIM OF PROJECT

1. To provide quality essential oil that would meet the demand of consumers. 2. To produce 7000kg of oil per annum 3. To make profit 4. To increase foreign exchange by exporting the essential oil produced 5. To create employment opportunities 6. To minimize project expense and cost of production. 7. To contribute in economic growth and development.

CHAPTER TWO 2. LITERATURE REVIEW 2.1

HISTORY OF ESSENTIAL OILS

Going far back as 425 BC, documentation on the use of essential oils could be found written by the great Greek historian Herodotus. He made mention of the Oil of Turpentine, and gave partial information on the ways of producing it.The first authentic description of real essential oils has been ascribed to Catalan Physician, Arnald de Villanova (1240-1311) who, by including products of distillation other than oil of turpentine, may be said to have introduced the art of distillation (Guenther, 1948). Since then, there has been advancement in the field of essential oil exploration, Evidence being that in 1607 Joseph Du Chesne in his famous book “Pharmacopoea Dogmaticorum Restituta” could state that “the preparations of essential oils is well known to everybody, even to the apprentices” . Today, development of new ways to extract oils, and improvement on the existing ways of extracting oils form plants are being made. 2.2 USEFULNESS OF ESSENTIAL OILS. Essential oils have variety of uses as seen in the society today, some industries which make use of this oils include; 1. Pharmaceutical Industry: As expectorant, antifungal, analgesic, antiseptic, for muscular ache etc. Here they are seen to have pharmacological effects through skin absorption and inhalation that medicinally benefits physical and psychological health. 2. Consumer-Care industry: Here it is used in shampoos, soap and detergents, hair cream, deodorants and other beauty products. 3. Food and Beverage industry: Here it is used as natural flavours and in the Agric-Food sector as pesticides.

Other uses are as fragrance, in brain waves measurement (Lavender Oil) and in hedonics (Kabuba, 2009). 4.

Aromatheraphy: Aromatherapy is a form of alternative medicine that uses volatile plant

materials, known as essential oils, and other aromatic compounds for the purpose of altering a person's mood, cognitive function or health. Science has discovered that our sense of smell plays a significant role in our overall health. Since ancient times Essential Oils have been used in medicine because of their medicinal properties, for example some oils have antiseptic properties. In addition, many have an uplifting effect on the mind, though different essential oils have different properties.

2.3 LEMON GRASS ESSENTIAL OIL Lemon grass (Cymbopogon Citratus) is a perennial plant with long, thin leaves which can be found in various parts of the world such as Asia, Africa, Australia and other tropical regions. The popularity of the plant is due to its use for various purposes such as a culinary herb in Asian cuisine and a medicinal herb in India. In several countries, lemon grass is used as a tea, it is also used as a preservative and pesticide. The oil extract of the lemon grass plant can be referred to as its essential oil. This oil has been investigated and has been found to have various properties which has rendered it useful for in various fields. As the lemon grass plant is seen to have variety of uses, so also is the lemon grass essential oil. The usefulness of the lemon grass essential oil is seen in various fields such as pharmacology (to treat various health ailments such as acne, athlete’s foot, flatulence, muscle aches and scabies), agriculture (as pesticides) and also in consumer care products such as perfumes, soaps, creams and flavouring agents for tea.

Gagan, et al., (2011) investigated the scientific basis for the therapeutic use of Cymbopogon Citratus (lemon grass). In this research, lemongrass essential oil was subjected to various activity test such as an Antifungal activity test, where the essential oil was seen to be active against dermatophytes such as Trichophyton mentagrophytes and Microsporum gypseum of Cymbopogon Citratus. In conclusion to their research, Gagan et al., (2011) said that Cymbopogon citratus contains various phytoconstituents such as flavonoids and phenolic compounds, terpenoids and essential oils, which may be responsible for the different biological activities, they also urged for further studies to be done to confirm their results. Boukhatem, et al., (2014) researched the use of lemon grass essential oil as a potent anti-inflammatory and antifungal drug. The antifungal activity of lemon grass essential oil was evaluated against several pathogenic yeast and filamentous fungi using disc diffusion and vapour diffusion method. Bankole & Joda, (2004) investigated the effect of lemon grass powder and essential oil on mould deterioration and aflatoxin contamination of melon seeds. I was seen that melon seeds mixed with lemon grass powder and essential oil showed almost no deterioration compared to the control melon seeds to which herbicides were not applied. The various work carried out by these various researcher’s show the usefulness of lemon grass essential oil in different fields. 2.4 COMPOSITION OF LEMON GRASS ESSENTIAL OIL Lemon grass plant is one which has a wide variety of species. The specie of the plant depends greatly on the region in which it is found. The lemon grass plant contains 1-2% of essential oil on dry basis (Ranitha, et al., 2014) and the chemical composition of the oil varies widely upon specie of the plant and agronomic treatment of the culture.

A breakdown of the Chemical composition of lemon grass is given in the table below CHEMICAL FAMILY

SPECIFIC COMPONENT

Monoterpenes

myrcene (10.2-18%), limonene (0.4%)

Aldehydes geranial (45.2%), neral (32.4%), citronellal (0.2%) Alcohols

a-terpineol (0.9%), citronellol (0.3%), geraniol (5.5-40%

Esters

geranyl acetate (1.2%)

Trace materials

camphene,

camphor,

α-camphorene,

Δ-3-

carene,caryophyllene, caryophyllene oxide, 1,8-cineole,

citronellal,

ndecyldehyde,

citronellol,

α,β-dihydropseudoionone,

dipentene,

β-elemene,

farnesol,

fenchone,

elemol,

farnesal,

furfural,iso-pulegol,

isovaleraldehyde, limonene, linalyl acetate, menthol, menthone, methyl heptenol,

Source: East-West school of Aromatic studies Lemon grass essential oil has high content of Citral (composed of geranial and neral isomers) which is used as a raw material for the production of ionone, vitamin A and beta-carotene

2.5 METHODS OF EXTRACTING ESSENTIAL OILS There are various ways through which essential oils can be extracted from plants; the method employed depends greatly on the plant material from which the oil is to be extracted and the desired end product i.e. the final use of the oil (Kabuba, 2009) 2.5.1 SOLVENT EXTRACTION METHOD Solvent extraction (solid-liquid extraction) works based on the principle that a solid brought in contact with a solvent is bound to lose its soluble content to the solvent. Thus, considering the removal of essential oil from plants material, the plant material is submerged in a vessel which contains a solvent (usually petroleum, ether or hexane) that the solute within the plant material would have a special affinity for. After leaving the solid-liquid mixture for a while, the solid is then separated from the liquid. The liquid which now is a mixture of essential oil and the solvent used for extraction are separated by evaporation and the simultaneous condensation of the vapour. 2.5.2 ENFLEURAGE This is a traditional method of extraction of oil from plants materials. It is an extraction method that is usually used for plant material which has low content of essential oil and heating them would more likely destroy the blossom before releasing the essential oil from the plant material. The enfluerage method has been said to be a “labour intensive way of extraction and an expensive process”.

To describe the method, flowers are placed on a tray and immersed in a container of

odourless vegetable or animal fat (usually cold) this is usually allowed to seat for some hours while the fat absorbs the essential oil from within the flowers. The flowers could be switched until the fat becomes saturated with essential oil. At this point, the flowers are removed from the fat and alcohol is then added to the fat in order to separate the essential oil from the fat. The essential oil is then recovered by evaporation of the alcohol. 2.5.3 COLD PRESSED EXPRESSION This is a method of extraction of essential oils at ambient temperature without the application of

extraneous heat. This method was practiced long before the process of distillation probably because the necessary tools were readily available for it (Hüsnü & Buchbauer, 2010). This method is used almost entirely for the extraction of citrus fruit oils, such as the oils from bergamot, lemon, lime, mandarin, orange, grapefruit etc. It is also known as the Sacrificial method. The process occurs thus; the fruit is furled on a surface with sharp projections that penetrate their peels thereby piercing the pouches containing the essential oil and causing the oil to be released. Mechanical pressure is then applied to the fruit to squeeze the juice from the pulp and the essential oil from the pouches. Seeing as the essential oil and the fruit juice are immiscible, the separate into different layers which is made more obvious by centrifugation after which separation is accomplished. A major drawback that the essential oil gotten with the use of the Cold Pressed Expression method have a relatively short shell life compared to oils gotten by other methods. 2.5.4 SUPER CRITICAL CO2 EXTRACTION: Supercritical CO2 extraction (SCO2) involves carbon dioxide heated to 87 degrees F and pumped through the plant material at around 8,000 psi, under these conditions; the carbon dioxide is likened to a 'dense fog' or vapor. With release of the pressure in either process, the carbon dioxide escapes in its gaseous form, leaving the Essential Oil behind. The usual method of extraction is through steam distillation. After extraction, the properties of a good quality essential oil should be as close as possible to the "essence" of the original plant. The key to a 'good' essential oil is through low pressure and low temperature processing. High temperatures, rapid processing and the use of solvents alter the molecular structure, will destroy the therapeutic value and alter the fragrance. 2.5.5 HYDRO-DISTILLATION Distillation is unquestionably the most popular and the most frequently used method for the extraction of essential oil from plants (Hüsnü & Buchbauer, 2010). The process of distillation is seen to be applied in various ways depending on economic, technological and some internal design constraints such as raw material and time. Regardless of the distillation process being used, the

basic procedure remains the same. It begins by heating water to its boiling point and the steam produced is then brought in contact with the plant material from which the essential oil is to be extracted from. When the plant material is subjected to heat in the presence of moisture from the steam, the essential oil is liberated from the plant. The liberated essential oil and steam mixture are then passed through a condenser, where they are cooled to liquid form and separated based on the immiscibility of the two liquids.

There are four various techniques of hydro-distillation which are used in the removal of essential oil from plants these techniques are; 1.

Water distillation

2.

Water and steam distillation

3.

Direct steam distillation

4.

Distillation with cohobation

CHAPTER THREE 3.0.

PROCESS ROUTE AND EQUIPMENT SPECIFICATION

3.1

PROCESS ROUTE SELECTION

Essential oils can be extracted using a variety of methods, although some are not commonly used today. Nowadays, a reputable distiller will try to preserve the original qualities of the plant, but the final therapeutic result is often not formed until after the extraction process. During extraction, the qualities of the oil change to give it more value - for example, chamazulene (characteristic of the pure blue colour of German Chamomile) is formed during the steam distillation process. Currently, the most popular method for extraction is steam distillation

. For the production of lemongrass oil, the technology that will be

used is STEAM DISTILLATION. Many old-time distillers favor this method for most oils, and say that none of the newer methods produces better quality oils.

3.2

STEAM DISTILLATION

Steam distillation is a special type of distillation or a separation process for temperature sensitive materials like oils, resins, hydrocarbons, etc. which are insoluble in water and may decompose at their boiling point. The fundamental nature of steam distillation is that it enables a compound or mixture of compounds to be distilled at a temperature substantially below that of the boiling point(s) of the individual constituent(s). Essential oils contain substances with boiling points up to 200°C. In the presence of steam or boiling water, however, these substances are volatilized at a temperature close to 100°C at atmospheric pressure. In this method of distillation, the steam used in the extraction of the essential oil from within the plant material is produced via a steam generator or boiler and channeled via pipes into the still which holds the plant material. The plant material is held in the still tank above the steam inlet and the steam is channeled through. The temperature of the steam must be high enough to vaporize the oil present, yet not so high that it destroys the plants or burns the essential oils. As they are released, the tiny droplets of essential oil

evaporate and, together with the steam molecules, travel through a tube into the condenser. The steam used in distillation is usually saturated or superheated, and frequently at atmospheric pressure. As the steam cools, it condenses into water. The essential oil forms a film on the surface of the water. To separate the essential oil from the water, the film is then decanted or skimmed off the top. The remaining water, a byproduct of distillation, is called floral water, distillate, or hydrosol. It retains many of the therapeutic properties of the plant, making it valuable in skin care for facial mists and toners. Steam distillation unit is usually preferred when large volume of plant material is being distilled to extract the oil. Some major advantage of the direct-steam distillation technique includes; 1) Increased efficiency of oil extraction. 2) The amount and quality of steam can be regulated 3) Most widely used process of extraction of essential oil for large scale extraction. 4) Throughout the flavor and fragrance supply industry it is the standard method of extraction. 5) Lower risk of thermal degradation as temperature generally will not be above 1100C. Hence, it is suitable for temperature sensitive material like lemongrass. 6) It is less labour intensive than other methods such as solvent extraction.

3.3

METHOD AND PROCEDURE

3.3.1 CUTTING This is the chopping of lemon grass into smaller diameter size before drying to enable proper reduction of moisture content in lemon grass and to give better drying result. Cutting process helps the lemon grass retain its colour, odour even after drying. Cutting of leaves enhance and help catalyze the production of the oil during the process. It is an advantage also because cutting can increase the quantity of the grass fed during the operation. Cutting also helps to increase the surface area that comes in contact with steam during distillation. Whole or uncut leaves occupy more space because of uneven distribution in the

still and it leads to lower yield of oil. The leaves will be cut in 2 cm lengths and the drying air temperature kept at 65 °C, because essential oil content and active principle concentration are high at this length and temperature, as described by Martinazzo et al. (2010). 3.3.2 DRYING The aim of drying is to reduce the moisture content of the lemongrass from 15% to 6%. This will increase the quality of essential oil produced. Dry leaves require less steam and fuel to distill Drying will be done at 65 °C for 30 minutes. Drying is a two stage process: firstly the transfer of heat to the wet lemongrass to vaporize the water in the product and secondly mass transfer of moisture from the interior to the surface where it evaporates. 3.3.3 DISTILLATION The dried and cut lemongrass leaves are placed in the plant chamber of the still and the steam from the boiler is allowed to pass through the leaves under pressure which softens the cells and allows the essential oil to escape in vapor form. The temperature of the steam must be high enough to vaporize the oil present, yet not so high that it destroys the plants or burns the essential oils (the temperature is set at 110 0C). As they are released, the tiny droplets of essential oil evaporate and, together with the steam molecules, travel through a tube into the condenser. 3.3.4 CONDENSATION The vapor that is produced by the still is liquefied using a condenser. Oil is adhering because it is more volatile than the steam. Condensation is done at 70 0C, at this temperature, the oil and water become immiscible and separation can be done. The liquid condensate forms a film or continuous layer of liquid that flows over the surface of the tube under the action of gravity. 3.3.5 OIL AND WATER SEPERATION This separates the oil from the water. It is usually done by letting the mixture settle in a large container. Since the oil is denser than water (hydrosol), it is collected at the top of the container. Separation is based

on gravity 3.3.6 PACKAGING Dark glass bottles will be used as packaging material because essential oil can easily react to sunlight, which may cause some changes in the quality of the product. 3.3.7 STORAGE Finished products are then kept in cool warehouses as to prevent the oil from deteriorating and loose its quality.

3.4

MODE OF OPERATION

The plant will be run using the SEMI-BATCH process. Semi-batch (semiflow) process operates much like batch process in that the lemongrass will be charged into the still tank in batches. However it is modified to allow continuous addition of steam. A normal batch reactor is filled with reactants in a single stirred tank at time t=0 and the reaction proceeds. A semi-batch reactor, however, allows partial filling of reactants with the flexibility of adding more as time progresses (here, the steam is added continuously to the still tank.

3.5

EQUIPMENT SPECIFICATIONS

They include:

1. Cutter 2. Dryer 3.

Boiler

4. Still tank 5. Condenser 6. Separator 7. Packaging Machine

1.

CHOICE OF DRYER

Rotary dryer (single shell dryer)

DESCRIPTION: The dryer is made up of a large, rotating cylindrical tube, usually supported by concrete columns. The dryer slopes slightly so that the discharge end is lower than the material feed end in order to convey the lemongrass through the dryer under gravity. The lemongrass to be dried enters the dryer, and as the dryer rotates, it is lifted up by a series the fins, it falls back down to the bottom of the dryer, passing through the hot gas stream as it falls. The dryer has advantage of reasonable structure, high efficiency and low energy consumption. The reason for this dryer choice is because the use of hot gas is very suitable and there is no loss of lemon grass to decomposition.. Rotary dryers also offer the option to cool, clean, shred, and/or separate the dried material.

DRYER SPECIFICATION Inclination – 3-5%

Capacity- 0.5- 1.5 tons/hr Motor power – 3Kw Weight of dryer – 2.4 tons Drying temperature – 65 oC

2.

BOILER:

The boiler will supply the steam required to evaporate the oil from the leaves of the lemongrass. It is designed to operate under specific conditions of pressure and steam rates considering efficiency and reliability. CHOICE OF BOILER: Fire tube boiler DESCRIPTION: In firetube boilers, the combustion gases pass inside boiler tubes, and heat is transferred to water on the shell side. The hot gas tubes are immersed into water, in a closed vessel. The fire tube heats up the water and converts the water into steam, and the steam remains in the vessel. It is capable of producing 17.5 kg/m3 and with a capacity of 9 metric tons of steam per hour. Firetube boilers are often characterized by their number of passes, referring to the number of times the combustion (or flue) gases flow the length of the pressure vessel as they transfer heat to the water. Firetube boilers are compact in size, they have low cost and the fluctuation of steam demand can be met easily. They are used to produce steam at low pressure. The opeating pressure is low (1 atm), therefore firetube boilers are sufficient.

BOILER SPECIFICATION Evaporation capacity- 125 kg/hr Maximum operating pressure – 4 bar Area of heating surface – 6.2 m2 Water capacity – 0.56m3

Efficiency – 80% Steam temperature – 151 oC

3.

STILL TANK:

The plant material is placed in the still and then required steam is supplied from the boiler to extract the oil. Some materials like Iron and copper react with essential oils and should therefore not be used for the construction of the tank. Stainless steel of grade 304 is the material of construction for the still tank. Stainless still will not react with the lemongrass oil, it is widely available, it is stable and it is the most widely used material for making still tank.

4.

CONDENSER:

The condenser converts the steam and oil vapour to liquid. This is very important and the rate of distillation depends on it. The condenser should be made from stainless steel. .It should be kept cool at all times to enhance its efficiency.

CHOICE OF CONDENSER: Surface condenser (shell and tube type) DESCRIPTION: This is the most important type of condenser used in the present day. Its main function is to condense low pressure steam. It has the advantage that the condensate (lemongrass oil and hydrosol) and the cooling water are entirely separate, rather they are separated by heat transfer wall. Hence condensate is pure and can be reused. This type of condenser has a large area of cooling sure compared to the systems volume. The steam passes through the condenser and condenser on contact with the cooling surfaces. The condensate collects in the bottom of the condenser from where it is pumped into the separator.

CONDENSER SPECIFICATION Shell: 0.20 m ID: 2.44 m long Tubes: 1 1/4 in. OD: 0.81 m long Single pass, cold-water-cooling element

5.

OIL WATER SEPARATOR:

This separates the oil from the water. It is usually done by letting the mixture settle in a large container. Since the water is denser than the oil, it is collected at the top of the container. We are using gravity separator. CHOICE OF SEPARATOR: Baffled type DESCRIPTION: The oil are separated forms a film of oil that is automatically skimmed off SEPARATOR SPECIFICATION: Height: 1 m

Pipe size: 1.4 gpm (Capacity) .

CHAPTER FOUR 4.0

MATERIAL AND ENERGY BALANCES

4.1 MATERIAL BALANCE W Wv

Mco F1

CUTTER

SEPARATION

F2 STILL

DRYER

CONDENSER

TANK

Fo

St Mci

P

Mass Balance From Law for mass conservation: {Accumulation within the system}= {input through system boundaries} – {output through system boundaries} + {generation within the system} – {consumption within the system}

Assumptions: 

Semi batch process



No reaction



There’s Perfect Mixing in the Tank



The Density of oil and water is constant



Wet lemon grass contained 15% moisture



The water lemon grass will be dried to 6%

(1)

Equation (1) becomes

{Input through system boundaries} = {output through system boundaries}

(2)

Hence material balance will be taken for every process The processes involved are: 1. Cutting 2. Drying 3. Distillation 4. Condensation 5. Oil-water separator Taking material balance around the still tank, condenser and separator Oil to be produced = 7000kg/year No of work days in a week = 5 days (Monday to Friday) No of days in a year = 52 x 5 = 260 days Hence, Producing 7000kg/year is equivalent to producing 26.9kg/day Basis: 1 day Yield: 1.5 %

F1 =

𝟕𝟎𝟎𝟎 𝟎.𝟎𝟏𝟓

= 466,667.67 kg/yr = 1794.87 kg/day

From experimental data gotten from “modification of an improved steam distillator for the extraction of essential oil in lemon grass” by Sulaiman Ifeloluwa i.

1 kg of lemon grass used 16L of water to produce the steam for steam distillation. Assumption: volume of water = volume of steam. If 1kg = 16 L Hence 27 kg = 432L

Hence, Mass of steam =

1000 𝑘𝑔 𝑚3

x 432 dm3 x (1m3 / 1000 dm3) = 432 kg

Fst = 432kg TERMINOLOGIES SPECIFICATION Fo= Mass of the moist lemon grass Wv= Mass of vapor leaving the moist lemon grass F1= Mass of the dried lemon grass coming from the dryer= Input to the still tank F2 = Mass of the lemon oil and the hydrosol mixture leaving the still tank hot St= Mass of the steam coming in from the Boiler W= Mass of the hydrosol F3 = Mass of the condensed lemon oil and hydrosol mixture P= Mass of the pure lemon oil The lemon grass contains 3% lemon grass oil

4.1.1 For the dryer

Based on dried lemon (6% of the moist grass) = 1794.87kg/day The amount of lemon grass without water 0.85 x Lg = 0.94 x 1794.87 Lg = 1984.92kg/day Water vapour = 1984.92 – 1794.87 = 190.05 kg/day

4.1.2 For the still tank and condenser

Still tank

CONDENSER BALANCE AROUND THE STILL TANK

F2 = 432 + 1794.87(0.06) + 1794.87(0.03) F2 = 432 + 107.69 + 53.85 F2 = 593.54 Accumulation = F1+ FSt -F2 Accumulation= 1794.87 + 432 -593.52 Accumulation = 1633.35kg

BALANCE AROUND THE CONDESER The mass of the cooling water in= The mass of the cooling water out Mco=Mci Balance for the oil mixture: F2 = F3 F3 = 593.54Kg

4.1.3 For the separator

F3 = P + W W = F3 – P W = 593.52 -26.9 = 566.62kg

To find the quantity of water vapour removed from the fresh Lemon grass during drying, an overall balance is carried out around the whole system. Input = Output

4.1.4 MATERIAL BALANCE FOR THE BOILER Feedwater = Steam/( 1 - % BD)

MASS OF STEAM=St = 432 kg Blow down= Assuming the blow down concentration is 10% as a result of the amount of solid and the maximum permissible concentration of solid inside the boiler drum Blowdown= 0.10 Fw= Mass of feed water Fw= 432/(1-0.10)= 432/0.90 Fw= 480kg

4.2

ENERGY BALANCE

A= still tank

B= condenser

C=Separator

For the dryer F1 = mass rate of lemon grass with 15% moisture content F2 = mass rate of dried lemon grass 6% moisture content. Qdrier = Qsensible + Qevaporation = ML CpL (dT) + MW LW MW = mass of water evaporated = 0.15 F1 – 0.06 F2 = 0.15 (1984.92) – 0.06 (1794.87) = 190.05kg Lw = 2260kJ/kg Qdrier = (190.05 x 2260) + (1794.87 x 2 (65 -25)) = 5.75 x 105 KJ/day Qdryer = 6.633 Kw

For the cutter : energy is assumed negligible compared to the other requirements.

BALANCE AROUND THE STILL TANK Heat provided by the steam from the boiler = heat needed to raise oil-water mixture to T1 + latent heat of oil-water mixture. Note: 

Water is entering the boiler at 25℃



Basis = 1day



Boiling point of water = 100℃



Boiling point of lemon grass oil = 224℃



The boiler is assumed to heat the water to 110 ℃ ( superheated steam)



Content of the still tank is raised to 110℃



The condenser is going to condense the oil water mixture to a temperature well below 100℃ to enable the oil and water to be in liquid form. Hence it is assumed that we are condensing the oil-water mixture to 70℃



Steam heating steam leaves the still tank at 50℃



Adiabatic operation

Major components of lemon grass oil Constituents

Molar mass (g/gmol)

Citral( C ) 152.2334 Nerol(N) 154.2493 Beta-mycerene(M) 136.23 CPO of water = 4.2 KJ/Kg.K

Latent

heat

of

vaporization (kj/mol) 62.50 62.90 50.60

Mole fraction (n) 0.9923 0.0391 0.0386

CPL of lemon grass oil = 2KJ/Kg.K

CALCULATION FOR LATENT HEAT



Latent heat of water = 2266 KJ/Kg



Specific Latent heat of oil (Loil)= nNLN +nCLC + nM LM = [(0.0391 x 62.9) + (0.9223 x 62.5) + (0.0386 x 50.60) ] = 62.05 KJ/mol



Molar mass of lemon grass is approximately = molar mass of Citral + molar mass of Nerol + molar mass of beta-mycerene = 152.2334 + 154.2493 + 136.23 = 442.71 g/gmol. 

specific Latent heat of oil (KJ/kg) is now gotten as = 140.16 KJ/kg



Hence latent heat of lemon grass oil = Moil Loil= 26.9 x 140.16 = 3770.3 KJ



Specific latent heat of water (Lw) = 2266.0 K J / k g

Q = energy lost by steam + energy gained by lemon grass oil and water Energy to raise temp of lemon grass oil and water = Mass of lemon grass and water = 107.69 + 26.92 = F3 = 134.61 kg/hr Mass accumulation = mass of spent lemon grass + oil left = 163.33 + (53.85 + 26.92) = 1660.26 kg/hr QLgO = ML Cp dT = 134.61 x 2 x (110-65) = 12114.9 KJ/hr

Energy to change the phase of oil water mixture

Qvapour = Mw Lw + Mo Lo = (107.69 x 2260) + (26.92 x3770.29) =3.49 x 105 kJ/day

Heat lost by steam Qsteam = 432 x 4.2 (70 - 110) = -72576 KJ/day

Energy to heat lemongrass Qlg = 1633.35 x 2 x (110-25) = 2.78 x 105 kJ/day

Overall Energy Balance of still tank Qstill-tank = 3.49 x 105 – 72576 + 2.78 x 105 Qstill-tank = 619424KJ/day Qstill-tank = 7.17KW

CALCULATION FOR HEAT REQUIRED GENERATED BY THE BOILER,. Assumptions: 1. Water is entering the boiler at 25℃ 2. Lemon grass is entering the still tank at 25℃ 3. Still tank and boiler are properly lagged 4. Water is heated to 110 ℃ 5. Mass of water = mass of steam

Mw = mass of water = 432kg

Qboiler = Qsensible + Qvapour Qvapour = Latent heat of water = Mw x Lw = 432 x 2266 = 978,912 KJ Qsensible = MwCPw(T2 – T1)= MwCPw(Tb– T0) = 432 x 4.2 x 85 = 154224 KJ Qb = 1133136 KJ/day In a day it will be 13.115KW

ENERGY BALANCE AROUND THE CONDENSER Assumption(s) 1. The cooling water is at 25 ℃ 2. The condenser is cooling to 70℃ So, heat removed by the condenser = heat lost by the oil water mixture + heat gained by cooling water

Heat gained by using 432 kg of water = 432 x 4.2 x (70-25) = 81648 kJ/hr

Heat lost by lemon grass oil (temperature change): Qsensible = 134.61 x 2.0 x (70 – 110) = - 10768 KJ/hr

Heat lost by water (temperature change) Latent heat of vaporization = - latent heat of condensation = MwCPw (T2 – T1) + MwL + MOCO (T2 – T1) + MOL(T2 – T1) = 539.69 x 4.2 x (70-110) +539.69 x -2266.05 + 59.38 x 2 x (70-110) + 59.38 x -3770.29 + 432 x 4.2 x (70-25) Qcondenser =-90667.92 – 1222964.53 -4750.4 – 223879.82 + 81648

Qcondenser = -1.459 x 106 KJ/day =-16.89KW



No energy balance for the separator as inlet temperature = outlet temperature

OVERALL ENERGY BALANCE

The total energy required (overall) = Qdryer + Qboiler + Qcondenser + Qstilltank = 13.115 – 16.89 +7.17 + 6.633 = 10.028 KW

CHAPTER FIVE 5.0

PROCESS FLOW DIAGRAM

This is a diagram used in chemical engineering to indicate general flow of plant processes and equipment. It displays the relationship between major equipment of a plant facility, it doesn’t show minor details such as piping details and designations. The process flow diagram includes: 

Process piping



Major equipment items



Control valves and other major valves



Connections with other systems



Recycle streams

STREAM

MEANING

FLOWRATE(kg/day)

Temperature

1984.92 n) bh))r)

25℃

1

Mass of wet lemon grass with 15% moisture

2

content Mass of Water vapor leaving the dryer

190.05

65℃

3

Mass of Dried lemon grass with 6%

1794.87

65℃

4

1794.87

65℃

5

moisture Mass of Cut lemon grass content Mass of water entering the storage

432

25℃

6

Mass of water leaving the storage

432

25℃

7

Mass of Pumped water(increased pressure)

432

25℃

8

Mass of steam going to the still tank

432

110℃

9

Mass of Water for condensation

432

25℃

10

Mass of condensed oil-water mixture

593.54

70℃

11

Mass of water leaving the condenser

432

70℃

12 13

Mass of Oil Mass of Hydrosol

26.92 566.62

70℃ 70℃

CHAPTER SIX 6.0

PIPING AND INSTRUMENTATION DIAGRAM

Stream

Description

Temp.

Pressure (atm)

(◦C)

Mass flow (kg/hr)

1a

Water leaving the storage

25

1

480

1b

Water leaving the boiler (going to still tank)

110

1

432

2

lemon grass dried from 15% to 6% moisture

65

1

1794.87

content

3a

Water from storage to condenser

25

1

432

3b

Pumped water (increased pressure) to the

25

1.5

432

condenser 4a

Steam plus lemon grass oil

110

1

566.61

4b

Condensed oil plus water

70

1

566.61

5

Lemon grass oil from seperator

70

1

26.92

6a

Hydrosol from separator

70

1

539.69

CHAPTER SEVEN 7.0

CHEMICAL ENGINEERING DESIGN OF THE MAIN PROCESS UNIT

7.1

INTRODUCTION

The still tank is needed to contain the lemon grass for which the oil will be extracted from it through steam distillation. Steam distillation is the process of passing steam through a closely packed bed of plant material placed in the tank still. The steam is obtained from an external boiler. Emerging vapor from the packed bed of plant of material containing the volatile essential oil is led to condenser for condensation. The condensed water is then separated from the immiscible oil in a vessel called separator. Crude essential oil obtained from the separator may be further redistill, dried, filtered or centrifuged to improve its appearance and keeping quality. This still tank contains two incoming streams, the first is the dried and cut lemon grass with a flow rate of 1734kg/day and the second stream is the steam coming from the boiler at 1100C and 1atm with a flow rate of 432kg/day. In the still tank is a Packed Bed, this is important because it offers a low pressure drop and it gives a continuous contact between the steam and the surface of the lemon grass which contains the lemon grass oil. This packed bed is also important because of the use of steam which is corrosive to trays.

7.2

MATERIAL OF CONSTRUCTION

Stainless steel is the material of construction. It is widely available. 1. Resistance to corrosion

Stainless steel has been shown to be resistant to corrosion and other chemical deterioration. .Stainless steel, with its superior anti-corrosive properties, can be a good choice in industrial environments that experience high temperatures. It will not react with the lemongrass oil 2. Good for the environment 70 percent of all steel in North America is recycled each year, and approximately 50% of steel is produced in facilities that use recycled materials or don’t emit CO2. It is a great choice for projects when it’s a priority to minimize environmental impacts. This environmental consciousness is becoming a greater and greater concern across all industries. 3. Cost-Effectiveness Stainless steel has high tensile strength, meaning they can withstand the same amount of pressure as other metals while being thinner in construction. This gives it a greater carrying capacity and makes it more cost-effective

7.3

CALCULATION AND ANALYSIS

1 Batch= 4hrs Mass of lemon grass=

1794.87𝑘𝑔 𝑑𝑎𝑦

1𝑘𝑔

4ℎ𝑟𝑠

x 8ℎ𝑟𝑠 x 𝑏𝑎𝑡𝑐ℎ

Mass of lemon grass = 897.435 kg/batch Basis= 1 batch Packing Density =300 kg/m3 For a cylindrical shaped vessel, the vessel is given by the equation Volume = 𝜋D2H/4 𝑀𝑎𝑠𝑠

Volume = 𝑃𝑎𝑐𝑘𝑖𝑛𝑔 𝐷𝑒𝑛𝑠𝑖𝑡𝑦

Volume =

897.435 300

= 2.992m3\

For this design, a height to diameter ratio is assumed based on literature (Design of essential oil plant from eucalyptus leaves) which is 2.5 i.e. H : D is 2.5, then D= Diameter of the tank = 1.151m H= Height of the tank = 2.877m Heat loss in the still tank Qsupplied = Qrecieved + UA∆Tcm UA∆Tcm = Qsupplied - Qrecieved UA∆Tcm = 7.17Kw {=Kj/s} ∆Tcm = 110 – 70 = 40oC U = 1⁄(𝛿⁄𝛾 + 1⁄𝛼) where γ =Heat transfer coefficient of insulator (fiber with binder) = 0.55Kw/mK δ = Thickness of the insulating material = 30mm α = Heat transfer coefficient of the constructing material (Stainless steel) = 0.016Kw/mK U= 0.01599 Kw/m2K 7.17

Therefore A = 0.01599 𝑋 45 == 9.967m2 A=𝜋𝐷𝐻 D= diameter of the still tank = 1.127m H= Overall height of the tank = 2.818m An inner holding shall be provided to ensure easy transfer of heat and removal of the spent lemon grass. This shall be constructed from the same material as the outside carbon steel

casings. An allowance of 0.005m between the two casings shall be provided. Total area of the the inner casing is 0.01 x 16 = 0.16m2. Therefore, L= (9.967 – 0.16)/(3.142 x 1.127) L=2.77m To find the voidage in the tank M=V(1-e)ῤ Where ῤ= Density of Lemon grass V=Volume of the still tank= 𝜋D2H/4 = 2.811m3 From literature, density of lemon grass is between 887-889 kg/m3 So solving for voidage, we have e = 0.64

7.4

PRESSURE DROP

It is important to be able to predict the drop in pressure for the flow of fluid streams through a packed column. The flow through beds composed of stationary granular particle is a frequent occurrence and are needed to predict the pressure drop across the beds due to resistance caused by the presence of the particles. In this chapter, Ergun’s equation will be used to predict the pressure drop in the packed column

fp is the packed bed friction factor ∆p is the pressure drop across the bed, L is the length of the bed (not the column), Dp is the equivalent spherical diameter of the packing, ῤ is the density of fluid, μ is the dynamic viscosity of the fluid, Vs is the superficial velocity (i.e. the velocity that the fluid would have through the empty tube at the same volumetric flow rate), and e is the void fraction of the bed (bed porosity at any time). μ = 1.3 x 10-5

L=3.379m

ῤ= 0.6kg/m3

Dp=25mm

Vs =

𝑓𝑙𝑜𝑤𝑟𝑎𝑡𝑒 𝑜𝑓 𝑠𝑡𝑒𝑎𝑚 𝐴𝑟𝑒𝑎 𝑥 𝑑𝑒𝑛𝑠𝑖𝑡𝑦

Grp = 66.47 ∆p = 1158.3N/m2

= 0.1614m/s fp= 4.007

∆p = 0.01146atm The pressure drop is 0.01146atm The final dimension of the still tank is Diameter: 1.13m Thick Plate: 50mm Capacity: 1000kg Height: 2.82m

CHAPTER EIGHT 8.0

MECHANICAL DESIGN OF THE STILL TANK

Vessel function: the still tank is used for the removal of the lemongrass oil from the lemon grass using steam. Operating temperature and pressure the still tank will be subjected to are 110℃ and 1 atm respectively. Maximum Allowable Working Pressure This is taken as the pressure at which the relief device is set. This will normally be 5 to 10% above the normal working pressure, to avoid spurious operation during minor process upsets. The normal working pressure of the still tank is 1atm. The maximum allowable working pressure is taken to be 1.1 atm

Maximum Design Temperature This is taken as the maximum working temperature of the stainless steel tank, with due allowance for any uncertainty involved in predicting vessel wall temperatures.

The temperature the tank will be subjected to is 110℃ , the maximum working temperature is set at 160℃ . 8.1

MAXIMUM ALLOWABLE STRESS

Considering maximum design temperature to be 160℃ , the corresponding maximum allowable stress using stainless steel of grade 304 is 101.97 N/mm2 . 8.2

THICKNESS OF THE STILL TANK WALL 𝑃 𝐷

𝑖 𝑖 t = 2𝑆𝐸−1.2𝑃

𝑖

where Pi is design pressure Di is the diameter of the vessel S is the max allowable stress E is the welding efficiency

Pi = 1.1 atm = 0.1114575 N/mm2 Di = 1.151m S = 101.97 N/mm2 E=1 0.1114575 × 1151

t = (2×101.97

×1)−(1.2 ×0.1114575)

= 0.629mm

Adding corrosion allowance of 6.371mm = 7mm Thickness of the wall is 7mm For the given diameter of the tank, (1.151m) the specified corresponding thickness should be taken to be 7mm

8.3

CLOSURE OF THE STILL TANK

This will be done using a torispherical head because it’s the most commonly used for cylindrical shells and for when operating pressure is below 15 bar. It is also very cost effective. Thickness of the closure is given by:

t=

0.885 Pi 𝑅𝑖 𝑆𝐸−0.1𝑃𝑖

Where Ri is the crown radius = Di 0.885 ×0..1114575 ×1151

T = (101.97 )−(0.1 ×0.1114575) = 1.11mm the thickness of the closure is 1.11mm

8.4

LOADS

The still tank will be subjected to other loads in addition to pressure and must be designed to withstand the worst combination of loading without failure. the maximum tensile stress. The main sources of load to consider are 1. Pressure 2. Dead weight of vessel and contents 3. External loads imposed by piping and attached equipment

The longitudinal and circumferential stresses due to pressure (internal or external), given by;

Longitudinal stress =

𝑃𝐷 4𝑡

Circumferential stress =

=

𝑃𝐷 2𝑡

0.1114575 ×1151 7 ×4

= 4.58 N/mm2

0.1114575 ×1151

=

7 ×2

= 9.16 N/mm2

Weight Loads The major sources of dead weight loads are 1. The vessel shell; 2. The vessel fittings: manways, nozzles; 3. Internal fittings: plates (plus the fluid on the plates); heating and cooling coils; 4. External fittings: ladders, platforms, piping; 5. Auxiliary equipment that is not self-supported; condensers, agitators; 6. Insulation;

Wv = total weight of the shell, excluding internal fittings, such as plates,

Cw = a factor to account for the weight of nozzles, manways, internal supports, etc., which can be taken as 1.08 for vessels with only a few internal fittings; 1.15 for distillation columns, or similar vessels, with several manways, and with plate support rings, or equivalent fittings;

Hv = height, or length, between tangent lines (the length of the cylindrical section), m; t = wall thickness, mm Dm = mean diameter of vessel (Di + t × 10-3) ,m

Wv = 240 Cw × Dm ( Hv + 0.8Dm)t Wv= 240 × 1.15 × 1.152722 (2.877 + 0.8×1.152722) 7= 8459 N = 8.5KN To calculate dead weight stress 𝑤𝑣 𝜋 (𝐷𝑖 +𝑡)𝑡

8.5

8459

= 𝜋 (1151+7)7 = 0.332 N/mm2

TEST FOR STABILITY

For the structure to be stable, the dead weight stress should be lower than the buckling stress. 𝑡 7 𝜎𝑐 = 2 × 104 ( ) = 2 × 104 = 121.63𝑁/𝑚𝑚2 𝐷𝑂 1151 Since the dead weight stress is significantly below the buckling stress therefore the structure is stable.

CHAPTER NINE 9.0

STATEMENT ON MATERIALS HANDLING

9.1

INTRODUCTION

American Materials Handling Society definition: Materials handling is the art and science involving the moving, packaging and storing of substances in any form.

Functional scope of materials handling within an industry covers the following:

(i) Bulk materials as well as unit materials handling. Bulk handling is particularly relevant in the processing, mining and construction industries. Unit materials handling covers handling of formed materials in the initial, intermediate and final stages of manufacture.

(ii) Industrial packaging of in-process materials, semi-finished or finished goods, primarily from the point of view of ease and safety of handling, storage and transportation. However, consumer packaging is not directly related to materials handling.

(iii) Handling of materials for storage or warehousing from raw materials to finished product stage.

A well designed materials handling system attempts to achieve the following:

i.

Improve efficiency of a production system by ensuring the right quantity of materials delivered at the right place at the right time most economically.

ii.

Cut down indirect labor cost.

iii.

Reduce damage of materials during storage and movement.

iv.

Maximize space utilization by proper storage of materials and thereby reduce storage and handling cost.

v.

Minimize accident during materials handling.

vi.

Reduce overall cost by improving materials handling.

vii.

Improve customer services by supplying materials in a manner convenient for handlings.

Lemon grass would be handled as a bulk load. The lemon grass will be fed into the still tank in 2 batches of 4 hours each. To obtain maximum yield of oil and to facilitate release of oil, the grass is chopped into shorter lengths. Chopping the grass will also be an advantage as more grass can be charged into the still and even packing is facilitated. The lemon grass will be stored in units of 20 kg in a wooden box (reason is for easy feeding in to the still tank since its going be handled mechanically). There will also be conveyor and conveyor belt to move the containers of lemon grass oil to the storage room.

9.2

LIFTING, TRANSPORTATION AND STORING MATERIALS

For an effective materials handling and storage program, safe lifting is only one aspect of material handling; transporting the load and safe storage is another.

When manually moving materials, employees should seek help when a load is so bulky that it cannot be properly grasped or lifted, when they cannot see around or over it, or when they cannot safely handle the load.

Handles or holders should be attached to loads to reduce the chances of getting fingers pinched or smashed. Workers also should use appropriate protective equipment. For loads with sharp or rough edges, wear gloves or other hand and forearm protection. In addition, to avoid injuries to the eyes, use eye protection. When the loads are heavy or bulky, the mover also should wear steel-toed safety shoes or boots to prevent foot injuries if he or she slips or accidentally drops a load.

All stacked loads must be correctly piled and cross-tiered, where possible. Precautions also should be taken when stacking and storing material. Stored materials must not create a hazard. Storage areas must be kept free from accumulated materials that cause tripping, fires, or explosions, or that may contribute to the harbouring of rats and other pests.

When stacking materials, height limitations should be observed. For example, lumber must be stacked no more than 16 feet high if it is handled manually; 20 feet is the maximum stacking height if a forklift is used. For quick reference, walls or posts may be painted with stripes to indicate maximum stacking heights.

Boxed materials must be banded or held in place using cross-ties or shrink plastic fibre.

Drums, barrels, and kegs must be stacked symmetrically. If stored on their sides, the bottom tiers must be blocked to keep them from rolling. When stacked on end, put planks, sheets of plywood dunnage, or pallets between each tier to make a firm, flat, stacking surface. When stacking materials two or more tiers high, the bottom tier must be chocked on each side to prevent shifting in either direction. When stacking, consider the need for availability of the material. Material that cannot be stacked due to size, shape, or fragility can be safely stored on shelves or in bins.

9.2

MATERIALS HANDLING WITH CONVEYOR.

When using conveyors, workers’ hands may be caught in nip points where the conveyor medium runs near the frame or over support members or rollers; workers may be struck by material falling off the conveyor; or they may become caught on or in the conveyor, being drawn into the conveyor path as a result.

To reduce the severity of an injury, an emergency button or pull cord designed to stop the conveyor must be installed at the employee’s workstation. Continuously accessible conveyor belts should have an emergency stop cable that extends the entire length of the conveyor belt so that the cable can be accessed from any location along the belt. The emergency stop switch must be designed to be reset before the conveyor can be restarted. Before restarting a conveyor that has stopped due to an overload, appropriate personnel must inspect the conveyor and clear the stoppage before restarting. Employees must never ride on a materials handling conveyor. Where a conveyor passes over work areas or aisles, guards must be provided to keep employees from

being struck by falling material. If the crossover is low enough for workers to run into it, the guard must be either marked with a warning sign or painted a bright colour to protect employees.

Screw conveyors must be completely covered except at loading and discharging points. At those points, guards must protect employees against contacting the moving screw; the guards are movable, and they must be interlocked to prevent conveyor movement when not in place.

9.3

STORAGE OF ESSENTIAL OIL.



Store in dark glass bottles: exposure to light can cause essential oil to oxidize rather quickly and lose their fragrance and any therapeutic qualities they may have had.



Note: plastics, no matter the colour, should generally be avoided. PET and HDPE plastics will not deteriorate from oil storage, but most other plastics are easily broken down to oil.



Use airtight solid caps for the containers to prevent air from entering and also the oil from getting out as it is volatile. Rubber lids may disintegrate after a relatively short period.



Storing essential oil in a refrigerator will protect them from sunlight and reduce chances of air exposure. Also refrigerators help keep the oil stable in cooler temperature. The temperature is 5◦C to 10◦C for optimal oil storage.



If oil congeal or solidifies at normal refrigerator temperature, the quality will not be adversely affected. The oil will return to its liquid state after being removed from the

refrigerator.



Do not put oils in the freezer, as freezing may damage the oil and diminish its quality.

 Avoid heat sources as most essential oils are flammable.

 Disposal: the spent lemon grass will be sold off as fodder animal feeding  The hydrosol will be sold to cosmetic industries.

9.4 

WORK STATION DESIGN The distance over which the load has to be moved should be reduced by relocating production and storage areas.

Work stations should be designed so that workers:



Can store and handle all material between knuckle and shoulder height; waist height is most desirable



Can begin and end handling material at the same height



Can face the load and handle materials as close to the body as possible



Do not have to handle loads using awkward postures or an extended reach, and



Do not handle loads in confined spaces that prevent them from using good body mechanics

CHAPTER TEN 10.0 MATERIAL SAFETY DATA SHEET 1.

PRODUCT INFORMATION

Product name: Lemongrass essential oil Chemical name: Not available Chemical formula: Not available Manufacturer: The CEOs Emergency telephone:

2.

INFORMATION ON INGREDIENTS

Lemongrass oil: 100% by weight

3.

HAZARD IDENTIFICATION

Concentrated product. Do not ingest. Observe good housekeeping May cause skin irritation. May cause eye damage. Carcinogenic effect: Not available Mutagenic effect: Not available Developmental toxicity: Not available

4.

PHYSICAL DATA

Physical state and appearance: non-viscous liquid Colour: brownish-yellow Odour: Citrus, lemon-like odour Density: 0.896g/mL at 25°C Refractive index: 1.479-1.491 at 20°C Boiling point: 224°C at 760mmHg Solubility: Soluble in alcohol, paraffin oil at 25°C pH: Not available Storage temperature: 2-8°C Shelf life: 24 months or longer if stored properly Storage: Store in a cool, dry place in tightly sealed containers, protected from heat and light

5.

FIRE OR EXPLOSIVE HAZARD DATA

Flammability of material: Combustible Flashpoint: 71°C Auto-ignition temperature: Not available Flammability limits: Not available Extinguishing media: Carbon dioxide, dry chemical powder or foam type extinguishers. Do not use water jets Special measures: Avoid inhalation of generated fumes. Use appropriate respiratory equipment

6.

STABILTY AND REACTIVITY DATA

Stability: The product is stable under recommended handling and storage conditions Incompatible materials: Strong acids, alkalis and oxidising agents Conditions of reactivity: When heated Decomposition: In the case of fire, dangerous decomposition products can be generated such as carbon monoxide and dioxide and nitrogen fumes.

7.

TOXOLOGICAL INFORMATION

Routes of entry: Inhalation, ingestion, eye contact Toxicity to humans: Substance is toxic to lungs, mucous membranes. Repeated or prolonged exposure can cause target organs damage Toxicity to animals: Not available Photo-toxicity: No additional data available Other information: Toxic to aquatic organisms, may cause long term adverse effects in the aquatic environment.

8.

ACCIDENTAL RELEASE MEASURES

Protective equipment: Wear protective clothing. Handle the product using protective gloves. Avoid contact with skin and inhalation of its vapours. Environment precautions: Do not discharge into drains, water courses or onto soil Method for cleaning up: For small spill, absorb with an inert material and dispose of in an appropriate waste disposal. For large spill, keep away from heat and sources of ignition. Ventilate area and wash spill site after material pickup is complete.

9.

ECOLOGICAL INFORMATION

BOD and COD: Not available Products of biodegradation: Possible hazardous short term degradation are unlikely. However, long term degradation products may arise Precautions: Prevent surface contamination of soil and surface water.

10.

EXPOSURE CONTROLS/PERSONAL PROTECTION

Engineering controls: Provide exhaust ventilation. Ensure eyewash stations and safety showers are proximal to the work-station location Respiratory equipment: Avoid breathing product vapour. For dealing with high concentration, use an approved respirator or equivalent when ventilation is inadequate Skin protection: Wear apron or protective clothing to avoid skin contact Hand protection: Wear chemical resistant gloves (PVC) to avoid skin contact Eye protection: Wear approved safety goggles Hygiene measures: Wash hands with soap and water after handling

11.

FIRST AID MEASURES

Inhalation: Remove victim from exposure site to ventilated area. Seek medical attention Eye contact: Remove any contact lenses. Rinse eyes with plenty of water. Do not use an eye ointment. Seek medical attention. Continue to rinse Skin contact: Remove contaminated clothing. Wash skin with soap and water. Seek medical attention if discomfort persists. Wash contaminated clothing before reuse

Ingestion: Do not induce vomiting. Rinse the mouth with water. Loosen tight clothing such as collar, belt, tie or waistband and move to a ventilated place

12.

DISPOSAL CONSIDERATIONS

Waste disposal: Avoid discharging into drainage water. Only eliminate by authorised companies.

CHAPTER ELEVEN 11.0 HAZARD AND OPERABILITY STUDIES SUMMARY (HAZOPs) 11.1 OVERVIEW A HAZOP study identifies hazards and operability problems. The concept involves investigating how the plant might deviate from the design intent. If, in the process of identifying problems during a HAZOP study, a solution becomes apparent, it is recorded as part of the HAZOP result; however, care must be taken to avoid trying to find solutions which are not so apparent, because the prime objective for the HAZOP is problem identification. Although the HAZOP study was developed to supplement experience based practices when a new design or technology is involved, its use has expanded to almost all phases of a plant's life. HAZOP is based on the principle that several experts with different backgrounds can interact and identify more problems when working together than when working separately and combining their results. The "GuideWord" HAZOP is the most well-known of the HAZOPs; however, several specialisations of this basic method have been developed. WHAT IS A HAZOP? A hazard and operability study (or HAZOP) is a systematic, critical examination by a team of the engineering and operating intentions of a process to assess the hazard potential of mal-operation or mal-function of individual items of equipment and the consequential effects on the facility as a whole.

It is quite normal to carry out safety reviews. These may take different forms. Experts may be consulted in isolation, without reference to each other. They may instead be gathered in lengthy meetings to discuss the particular topic. Hazops are meetings with a distinct structure, the structure imposing a certain organization, to enhance effectiveness. They are a generalized study technique, equally applicable to microchip manufacture, pharmaceutical synthesis, effluent plant operation or any process. They should not be seen, however, as a solution to all ills, the ultimate review. The procedure is only anther tool in the safety locker and should be seen as complementary to other techniques. Indeed it is best applied as one stage of a multi-stage procedure, applying different techniques as relevant to each stage. It does not replace, but rather supplements, existing Codes of Practice. Neither can it totally substitute for experience. But, both Codes of Practice and experience are evolved from existing situations. Innovative developments require a review which investigates the unknown. Hazops are a systematic, logical approach to determining problems.

Why is a HAZOP Carried Out? The reasons for carrying out hazard and operability studies, are: i. Primarily, to identify hazards, and ii. To a lesser extent, to resolve these hazards.

In saying this, hazards are very generally defined. They are understood to be events, which:-

i. Lead to injury of people, either inside or outside the plant. ii. Injure the environment. iii. Insult the environment. Harmful effects may not occur, but disturbance itself is unacceptable. iv. Damage the plant, an obvious hazard. v. Result in loss of production quantity, quality or schedule. In practice, some resolution of hazards is normally accepted. However a careful balance must be maintained to ensure that the primary purpose of hazard identification is not compromised.

When is a HAZOP Carried Out? The timing of a hazard and operability study is determined by the objectives of a study, and in turn determines the benefits that may be gained. The outline concept of a process may be examined to highlight any major omissions or significant features. As further detailing is carried out, e.g. when the process design is complete, the full study procedure may best be applied. Operating procedures may be examined to ensure that all eventualities have been considered. Modifications including so-called “minor modifications”, generally benefit from a rigorous study. Often an apparently simple, uncomplicated modification can give rise to a greater problem than it was intended to solve. Existing plant and new equipment are other examples of topics that may benefit from study. Therefore a project may be studied several times in its life-time.

Despite these comments there is quite a distinct benefit from carrying out a proper HAZOP Study in terms of the correct timing and to obtain the maximum cost benefit. Therefore, a hazop cannot be carried out before the line diagrams (or process instrumentation diagrams as they are often called) are complete. It should be carried out as soon as possible thereafter. If an existing plant is being studied the first step is to bring the line diagrams up to date or check that they are up-to-date. Carrying out a hazop on an incorrect line diagram is the most useless occupation in the world. It is as effective as setting out on a journey with railway timetable ten years out of date. A hazop takes 1.5-3 hours per main plant item (still, furnace, reactor, heater, etc.). If the plant is similar to an existing one it will take 1.5 hours per item but if the process is new it may take 3 hours per item. Meetings are usually restricted to 3 hours, twice per day, 2 or 3 or even 4 days per week, to give the team time to attend to their other duties and because the imagination tires after 3 hours at a stretch. The hazop on a large project may take several months, even with 2 or 3 teams working in parallel on different sections of the plant. It is thus necessary to either: a) Hold up detailed design and construction until the hazop is complete, or b) Allow detailed design and construction to go ahead and risk having to modify the detailed design or even alter the plant when the results of the hazop are known.

Ideally, the design should be planned to allow time for (a) but if completion is urgent (b) may have to accept - but this is not a widely accepted option due to the cost implications. A preliminary hazop may be carried out on the flowsheet before detailed design starts. This will take much less time than the hazop of the line diagrams and will identify ‘area’ of the process of a particular hazardous nature. It provides a more “structured” and “systematic” approach than a preliminary design review - but NOT the detailed analytical data of a true P&ID HAZOP.

CONCEPT The HAZOP concept is to review the plant in a series of meetings, during which a multidisciplinary team methodically "brainstorms" the plant design, following the structure provided by the guide words and the team leader's experience. The primary advantage of this brainstorming is that it stimulates creativity and generates ideas. This creativity results from the interaction of the team and their diverse backgrounds. Consequently the process requires that all team members participate (quantity breeds quality in this case), and team members must refrain from criticizing each other to the point that members hesitate to suggest ideas. The team focuses on specific points of the design (called "study nodes"), one at a time. At each of these study nodes, deviations in the process parameters are examined using the guide words. The guide words are used to ensure that the design is explored in every conceivable way. Thus the team must identify a fairly large number of deviations, each of which must then be considered so that their potential causes and consequences can be identified. The best time to conduct a HAZOP is when the design is fairly firm. At this point, the design is well enough defined to allow meaningful answers to the questions raised in the HAZOP

process. Also, at this point it is still possible to change the design without a major cost. However, HAZOPs can be done at any stage after the design is nearly firm. For example, many older plants are upgrading their control and instrumentation systems. The success or failure of the HAZOP depends on several factors: 

The completeness and accuracy of drawings and other data used as a basis for the study



The technical skills and insights of the team



The ability of the team to use the approach as an aid to their imagination in visualizing deviations, causes, and consequences



The ability of the team to concentrate on the more serious hazards which are identified.

The process is systematic and it is helpful to define the terms that are used: a. STUDY NODES - The locations (on piping and instrumentation drawings and procedures) at which the process parameters are investigated for deviations. b. INTENTION - The intention defines how the plant is expected to operate in the absence of deviations at the study nodes. This can take a number of forms and can either be descriptive or diagrammatic; e.g., flow sheets, line diagrams, P&IDS. c. DEVIATIONS - These are departures from the intention which are discovered by systematically applying the guide words (e.g., "more pressure"). d. CAUSES - These are the reasons why deviations might occur. Once a deviation has been shown to have a credible cause, it can be treated as a meaningful deviation. These causes can be

hardware failures, human errors, an unanticipated process state (e.g., change of composition), external disruptions (e.g., loss of power), etc. e. CONSEQUENCES - These are the results of the deviations should they occur (e.g., release of toxic materials). Trivial consequences, relative to the study objective, are dropped. f. GUIDE WORDS - These are simple words which are used to qualify or quantify the intention in order to guide and stimulate the brainstorming process and so discover deviations. The guide words shown in the following table are the ones most often used in a HAZOP; some organisations have made this list specific to their operations, to guide the team more quickly to the areas where they have previously found problems. Each guide word is applied to the process variables at the point in the plant (study node) which is being examined.

OVERALL PROCEDURAL STEPS IN AN HAZOP STUDY 1. Company PHA/Safety/PSMP Team Meet 2. Identify the Project for the HAZOP Study 3. Identify the Lead Process Engineer 4. Select the HAZOP Team Leader 5. Define Purpose and Scope of HAZOP 6. Select the Team/Define Roles

7. Pre-HAZOP Meeting 

Lead Process Engineer and HAZOP Study Leader



Identify and Obtain Required Information



Plan the Study Sequence



Plan the Schedule

8. Inform Everyone Concerned 9. HAZOP Study Review and Documenting the Results (Minutes) 10. Preparing and Submitting the HAZOP Study Report 11. Taking the Actions 12. Close-Out Meeting and Signing Off.

HAZOP STUDY PROCEDURE The outline steps for the overall HAZOP Study methodology are shown in the table. A potential HAZOP Study Leader or HAZOP Study Chairperson must be aware of all of these. However, many people - engineers, chemists, project managers, process operators, maintenance staff, services engineers, contractors, equipment suppliers, control systems staff etc. etc. - will be required to attend and participate in HAZOP Studies. Consequently, as part of introducing HAZOP it is worthwhile early on in this course for us to look at two aspects of the study method relating to Blocks 7 and 9 in the Table. Two methods of importance in the “practical side” of performing a HAZOP Study are:

- Defining each Pipe section to be studied. This should have been agreed previous to the actual HAZOP Study Meeting between the HAZOP Study Chairman and the Lead Process Engineer - Application of the Guide Words 

Process Section

The section to be studied is usually a section of pipeline between two main process items on a P&ID (piping and instrumentation diagram) - for continuous process operations. Usually the analysis is carried out on final P&ID’s, that is, prior to “Issue for Construction”. Frequently the section of line undergoing a HAZOP Study may go through several other items of equipment which must be considered but providing there is no chemical change it is acceptable and normal to HAZOP in this way. Sometimes an additional chemical may even be added into the line (via a branch line, e.g. T junction on Y junction) and these “in-line” additions are usually included as part of the HAZOP of this particular section - but NOT always the branch line. When the Pipe section has been followed through to the equipment item it is usual to assess the equipment item as part of the “same section” by applying a number of equipment guidewords. The same method, of course, applies to the equipment item at the beginning of the process. The whole HAZOP process usually starts with the engineering drawing(s) at the BEGINNING of the process, the feeds being the raw materials. Often as many as 3 or 4 P&ID’s may be tabled at one session to enable the HAZOP team to identify where streams are coming from on one or more P&ID’s and where they are going to on the next one or two P&ID’s.

HOW ARE HAZOPs DONE?

Earlier, these studies were defined as examinations of engineering and operating intentions. An intention is the expected behaviour of a process and its associated hardware, under normal and abnormal conditions. It may be defined diagrammatically or descriptively; diagrammatically in terms of flowsheets, P&ID’s. Etc. or descriptively with operating instructions or design specifications. A very important assumption is that no hazard can arise from an intention that behaves as expected, i.e. no one deliberately builds in a hazard. Therefore, a hazard can arise only if there is a deviation from the expected behaviour. Hypothetical deviations are prompted by applying guide words, which will be explained shortly, to each intention. Consequently the design basis is not explicitly challenged and process alternatives may not be recognized. For example, it is proposed that excess pressure may exist in a line. Firstly, it must be established if there is a realistic cause of this deviation. If there is, the consequences must be considered. They may be trivial or significant. If significant, they must be evaluated to see if they constitute a hazard. In the example of line over-pressure, the excess may be within the line rating. This consequence is trivial. If the rating is exceeded, however, rupture may result. This is obviously a hazardous occurrence. The study procedure may be broken into several distinct steps and is shown in the Table. We must define the scope of the study, select a team to carry it out, and make the necessary preparations before the examination itself can be carried out. Arising from the examination will be a number of follow-up activities. Finally a detailed record of the study is also necessary; but now we will consider the “Application of the Guidewords” to a particular “Section” or “Study Node”. The other steps can be chosen to be elaborated on.

HAZOP GUIDE WORDS AND MEANINGS Guide Word Meaning No

Negation of the Design Intent

Less

Quantitative Decrease

More

Quantitative Increase

Part Of

Qualitative Decrease

As Well As

Qualitative Increase

Reverse Logical

Opposite of the Intent

Other Than `

Complete Substitution

These guide words are applicable to both the more general parameters (e.g. react, transfer) and to the more specific parameters (e.g. pressure, temperature, flow). With the general parameters, meaningful deviations are usually generated for each guide word. Moreover, it is not unusual to have more than one deviation from the application of one guide word. For example, "more reaction" could mean either that a reaction takes place at a faster rate, or that a greater quantity of product results. With the specific parameters, some modification of the guide words may be necessary. In addition, it is not unusual to find that some potential deviations are eliminated by physical

limitation. For example, if the design intention of a pressure or temperature is being considered, the guide words “more” or "less" may be the only possibilities. Finally, when dealing with a design intention involving a complex set of interrelated plant parameters (e.g., temperatures, reaction rates, composition, or pressure), it may be better to apply the whole sequence of guide words to each parameter individually than to apply each guide word across all of the parameters as a group. Also, when applying the guide words to a sentence it may be more useful to apply the sequence of guide words to each word or phrase separately, starting with the key part which describes the activity (usually the verbs or adverbs). These parts of the sentence usually are related to some impact on the process parameters.

TABLE Creating Deviations Guide Words

Parameter

Deviation

NO

+

FLOW

=

NO FLOW

MORE

+

PRESSURE

=

HIGH PRESSURE

AS

WELL +

ONE PHASE

=

TWO PHASE

AS

Guide words are applied to both the more general parameters (e.g. react, mix) and the more specific parameters (e.g. pressure, temperature). With the general parameters, it is not unusual to

have more than one deviation from the application of one guide word. For example, “more reaction” could mean either that a reaction takes place at a faster rate, or that a greater quantity of product results. On the other hand, some combinations of guide words and parameter will yield no sensible deviation (e.g. “as well as” with “pressure”). With the specific parameters, some modification of the guide words may be necessary. In addition, we often find that some potential deviations are irrelevant because of a physical limitation. For example, if temperature parameters are being considered, the guide words “more” or “less” may be the only possibilities. The following are other useful alternative interpretations of the original guide words: 

Sooner or later of “other than” when considering time



Where else for “other than” when considering position, sources, or destination



Higher and lower for “more” and “less” when considering levels, temperature, or pressure

11..2 HAZOP STUDIES ON SELECTED EQUIPMENT In this section, the detail discussion on HAZOP studies will cover the still tank, the heat exchangers (heater, cooler).

HAZOP STUDIES ON THE HEAT EXCHANGERS (BOILER AND CONDENSER) AND STILL TANK

Guide Word

Deviatio n

Possible Cause

Consequence s

Existing Safeguards

NO

NO FLOW

1. Faulty pump

Level decrease in still tank, loss of steam in still tank, Low output of vapor mixture

Flow indicator provided.

Shutdown system

flooding in the still tank

pressure indicator provided

Reduce flow of water into the boiler

2. Broken pipe or plugging MORE MORE FLOW

MORE PRESSUR E

1. High pressure from boiler

2. Early filling of Discharge still tank valve fully open than required set value.

Flow indicator provided.

3. Failure of the process water pump to the boiler

Low/high pressure of water into the boiler, exceeded boiler capacity, poor steam quality

Pipe bypass from the tank provided, flow indicator provided

1. Same as no. 3 in more flow.

Same as above,

2.

Fa

Fire and explosions, tube rupture

Action Required

Action taken

Operators and Technicians

Mechanical Engineers

set the discharge valve back to the required value shutdown of the pump and opening up the bypass

High pressure alarm

Check the control valve and shutdown if necessary.

Pressure

Replace the

Operators and technicians

indicator and controller

ilure of control valve 3. Hi gh tempera ture in the still tank

MORE TEMPER ATURE

MORE TEMPER ATURE

LESS

1. Poor/No cooling in the condense r.

tube

Install high pressure alarm

Desired separation not achieved

Temperatu re indicator/c ontroller provided

Allow flow of cooling water into the condenser

Flow indicator provided.

LESS FLOW

Pipe partial plugged or leakage

1. Level decrease in distillation column 2. No flow of same as vapour more flow mixture out of the still tank

Shutdown system

LESS PRESSUR E

same as no. 3 in more flow

same as more flow, production loss, decrease in production

same as more flow Replace the leaking pipe,

Technicians

Technicians

LESS TEMPER ATURE

Temperatu re indicator/c ontroller provided

changes in action, valve fully opened, pipeline leakage

rate

Damaged insulation in the still tank.

loss of temperature in the still tank

Install low temperature warning device

Quality Assurance Team

flow decrease in the still tank

scheduling maintenanc e

Quality Assurance and Operators

Install new pump and low pressure alarm.

No heat provided/ supply failure REVE RSE

REVERSE FLOW

Pipe partial plugged or leakage

1. moisture separator for the gas 2. Pretreating of the water OTHE R THAN

Utility failure, Mainten ance, Leak, Safety, Corrosio n, Instrume ntation

1. Routine maintena nce 2. very high pressure in the pipes 3. High moisture

1. No production of lemon grass oil 2. Explosion of pipes 3. Explosion in the plant 4. corrosion and leakage of the

shutdown of plant

Quality Assurance Team

etc

content in the natural gas 4. Pipelines conveyin g oxygen, moisture and chemical salt.

pipelines

Environ mental impact

Incomple te combusti on

emission of carbon monoxide

Install oxygen trims to control fuelair ratio

Chemical Engineers and Operators

HAZOP STUDIES ON STORAGE TANK: The HAZOP study for storage tank involves storage flow parameters

Guide

Deviation

Possible causes

Consequences

Action required

word NO

Level tank Loading more from Tank overfills

Install relief valve in

(no flow)

the storage tank.

the feed line. Reverse flow from the process pump. Control valve failure

possible cause of fire and explosion hazards.

Install

high-level

alarm. Install

flow

high

Line fracture

shut down.

Line blockage

Regular check on the pipeline valve and pump

MORE

Pressure (more flow)

Control valve fails. Tank Failure overfills in valve

burst

if Regular check on

continue the pipeline than the

the tank.

failing.

Pump failure

Explosion hazards Install

Temperature of inlet

might occur.

is hotter than normal

valve pressure

relief valve in the tank

volatile impurities in

Install pressure high

the feed.

shutdown alarm. Avoid

any

direct

heat to the tank. Prepare for fire.

CHAPTER TWELVE 12.0 SITE LAYOUT AND PLANT LAYOUT 12.1 `SITE LAYOUT

12.2 SITE SELECTION The location of the lemongrass producing plant is Igbesa, Ogun state. The reasons for choosing this location are: 

Location, with respect to the marketing area : Igbesa is close to commercial areas like Lagos and Ibadan, where the target market is located



Raw material supply and suitable land: The Lemongrass will be grown on a farmland, there is large expanse of land in Igbesa for cultivation of Lemongrass



Transport facilities



Availability of labor



Availability of utilities: water, fuel, power



Environmental impact, including effluent disposal



Local community considerations



Climate



Political and strategic considerations.

12.3 PLANT LAYOUT

12.4 FACTORS CONSIDERED FOR PLANT LAYOUT 

Economic considerations: construction and operating costs



The process requirements



Convenience of operation



Convenience of maintenance



Safety



Future expansion



Modular construction.

CHAPTER THIRTEEN 13.0 ECONOMIC EVALUATION OVER FIFTEEN YEAR PERIOD 13.1

PLANT CAPACIITY

The market study of Lemongrass oil indicates that the unsatisfied demand for the year 2017 is 1400 tonnes, while this figure would grow to 2700 tonnes by the year 2024, the envisaged plant will, therefore, have an annual production capacity of 7,000kg of Lemongrass oil. The plant will operate single shift of 8 hours a day and for 260 days a year. 13.2

PRODUCTION PROGRAM

The Lemongrass oil plant will start operation at a lower production capacity to allow time for market penetration and skill development of production workers. Thus, production will start at 65% of installed capacity during the first year of operation, and then will grow to 80% in the second year, 90% in the third year, and run at its full capacity from the fourth year

DESCRIPTION Lemon Grass Oil produced (kg) Percentage of capacity utilized

1 4550 65%

PRODUCTION YEAR 2 3

4

5 TO 15

5600

6300

7000

7000

80%

90%

100%

100%

13.3 MANPOWER REQUIREMENT Manpower required for the plant is both for administrative activities and production. The total manpower required is 40 persons. Of this production workers are 20 while the rest are administrative and supervisory staff. Details of manpower requirement and annual cost, including workers benefit is given in the table below

Job title

Number Required

Monthly Salary

Annual Salary (N)

Plant Manager

1

150,000

1,800,000

Secretary

1

80,000

960,000

Administrator

1

120,000

1,440,000

Accountant

1

70,000

840,000

Clerk

1

70,000

840,000

Commercial head

1

80,000

960,000

Store Keeper

2

30,000

720,000

Purchaser

2

30,000

720,000

Cashier

1

30,000

360,000

Accounts clerk

1

30,000

360,000

Office boy

1

10,000

120,000

Driver

3

20,000

240,000

Guards

4

20,000

240,000

ADMINISTRATIVE

Bonus Sub-Total

400,000 20

10,000,000

PRODUCTION Production and

1

100,000

1,200,00

1

50,000

600,000

technical head Production foreman

Operator

7

40,000

3,360,000

Boiler operator

4

25,000

1,200,000

Laborers

5

15,000

900,000

Electrician

1

15,000

180,000

Mechanic help

1

15,000

180,000

Bonus

200,000

Sub-Total

20

7,010,000

Total

40

17,010,000

13.4

RAW MATERIAL PROCUREMENT

The lemongrass will be grown in Igbesa, Ogun state, Nigeria. Growing the lemongrass is more economical than buying. 1kg of lemongrass costs ₦500 (price gotten from local farmers in Ogun state). According to the of Department of Agriculture, Forestry and Fishery in Republic of South Africa, an average of 50 metric tons of lemongrass can be harvested per hectare per annum. Production capacity is 7,000kg of lemon grass oil per annum; Number of working days per year: 260 (Mon - Fri). Yield: 1.5 % 7000

Feed = 0.015 = 466,667.67 kg/yr = 1794.87 kg/day Mass of dry lemongrass needed per day (6% moisture): 1794.87kg Mass of wet lemongrass purchased (15% moisture) : 1984.92kg Mass of lemongrass needed per year: 1984.92 x 260 = 516.08 tons 10 hectares of land will be purchased to carry out this project. 1 hectare of land in Igbesa, Ogun state costs ₦650,000 (according to Nigerian property centre). Therefore 10 hectares of land costs ₦6,500,000 RAW MATERIALS The raw materials needed to start up the cultivation of lemon grass include: 

Seedlings



Soil nutrients



Tools



Drums for storage

Cost of cultivation for 10 hectares of land

S/N

ITEM

1YR

2YR

3YR

4YR

5 YR -15 YR

1

Land

6,500,000

2

Land leveling,

100,000

50,000

50,000

50,000

50,000

450,000

-

-

-

-

ploughing etc. 3

Seeds/planting material

4

Soil nutrients

400,000

400,000

400,000

400,000

400,000

5

Weeding and irrigation

100,000

100,000

100,000

100,000

100,000

6

Nursery maintenance

50,000

50,000

50,000

50,000

50,000

7

Drums for storage

1,000,000

-

-

-

-

8

Wages of farm

1,000,000

1,000,000 1,000,000 1,000,000 1,000,000

Sub Total

9,500,000

600,000

600,000

600,000

600,000

Contingency 10%

350,000

200,000

200,000

200,000

200,000

Total

9,850,000

1,800,000 1,800,000 1,800,000 1,800,000

workers

13.5 PLANT AND MACHINERIES S/N

EQUIPMENTS

SPECIFICATIONS

QTY

COST (N)

1

BOILER

water tube boiler

1

421,200

1

1,650,000

Evaporation capacity- 125 kg/hr Maximum operating pressure – 4 bar Area of heating surface – 6.2 m2 Water capacity – 0.56m3 Efficiency – 80% Steam temperature – 151 oC

2

ROTARY DRYER

Inclination – 3-5% Capacity- 0.5- 1.5 tons/hr Motor power – 3Kw

Weight of dryer – 2.4 tons

3

STILL TANK

Diameter: 1.16m

1

1,000,000

1

1,000,000

1

1,250,000

1

700,000

Height: 3.58m Thick plate: 50mm Capacity: 7000 kg 4

CONDENSER

Shell and Tube condenser Shell: 0.20 m ID: 2.44 m long Tubes: 1 1/4 in. OD: 0.81 m long Single pass, cold-water-cooling element

5

OIL AND WATER SEPARATOR

Baffled type Height: 1 m Pipe size: 1.4 gpm (Capacity)

6

COOLING TOWER

Type: induced draft Function: provide cooling water to the condenser Pressure: atmospheric -Corrosion resistance of polyethylene and PVC plastic construction in critical contact areas. - 97% return of process water to the heat load for reuse. Diameter: 0.9 m Height: 6 m

7

WATER TANK

Capacity: 24.54 m3 (cylinder)

2

1,500,000

1

500, 000

2

1,400,000

Diameter: 2.5 m Height: 5 m Materials of Construction: SS 304 8

WASHING TANK

Capacity: 5.30 m3 (cylinder) Diameter: 1.5 m Height: 3 m Materials of Construction: S-2 Steel plate Grade B

9

PUMP

2 stage deep well pump Performance: Flows to 3,785 L/min Heads to 3,658 m Pressure: 4,500 psia

10

WEIGHING MACHINES

2

200,000

11

LEMON GRASS DRUMS

10

1,000,000

12

STORAGE TANKS

2

2,500,000

13

CONVEYOR BELT

Width: 14 in.

500,000

Capacity: 60 kg/hr Belt Speed: 200 ft/min Power: 0.2186 Hp = 0.1630 Kw 14

13.6

MISCELLENOUS

1, 000,000

TOTAL

13,621,000

COST OF UTILITIES

UTILITY

SOURCE

QUANTITY

COST (₦)

1.

Electricity

KWh

45,000

958,500

2.

Fuel

Lt

13,000

1,950,00

TOTAL

13.7

2,908,500

INITIAL INVESTMENT COST ITEMS

COST (₦)

1

Raw material procurement

9,850,000

2

Land, Building and Constructions

10,000,000

3

Plant and machineries

13,261,000

4

Plant setup

3,000,000

5

Office Setup

2,500,000

6

Generator (30kVa)

1,200,000

7

Borehole installation

300,000

8

Vehicle

2,500,000

9

Pre-production Expenditure

2,500,000

TOTAL

45,211,000

13.8

FULL CAPACITY PRODUCTION COST (ANNUAL)

ITEMS

COST(₦)

NATURE OF COST (Fixed/Variable)

Raw Materials

1,800,000

Fixed

Utilities

2,908,500

Variable

Manpower

17,010,000

Fixed

Maintenance

1,000,000

Variable

Operating costs

4,000,000

Variable

Packaging

1,000,000

Variable

Sales promotion and

1,500,000

Variable

Depreciation

4,000,000

Fixed

Transportation

400,000

Variable

Finance

1,600,000

Fixed

Total

35,213,000

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13.9 PROJECTED REVENUE Based on a price of ₦9,000 per kg of lemongrass oil, and a price increase of 10% every 5 years, the following projections may be made: YEAR

REVENUE (₦)

First year

40,950,000

Second year

50,400,000

Third year

56,700,000

Fourth year

63,000,000

Fifth year

63,000,000

Sixth year

70,000,000

Seventh year

70,000,000

Eighth year

70,000,000

Ninth year

70,000,000

Tenth year

70,000,000

Eleventh year

77,000,000

Twelfth year

77,000,000

Thirteenth year

77,000,000

Fourteenth year

77,000,000

Fifteenth year

77,000,000

90,000,000 80,000,000 70,000,000 60,000,000 50,000,000 40,000,000 30,000,000 20,000,000 10,000,000 0

Fig4.1 graph showing projected revenue

13.10 ANNUAL PROFIT This was also estimated assuming a 10% increase in cost of production every 5 years.

YEAR

Profit (N)

First year 5,737,000 Second year 15,187,000 Third year 21,487,000 Fourth year 27,787,000 Fifth year 27,787,000 Sixth year 34,787,000 Seventh year 34,787,000 Eighth year 34,787,000 Ninth year 34,787,000 Tenth year 34,787,000 Eleventh year 41,787,000 Twelfth year 41,787,000 Thirteenth year 41,787,000 Fourteenth year 41,787,000 Fifteenth year 41,787,000

45,000,000 40,000,000 35,000,000 30,000,000 25,000,000 20,000,000 15,000,000 10,000,000 5,000,000 0

Figure 4.2: graph showing profit Profitability According to the projected income statement, the project will start generating profit in the first year of operation. 13.11 BREAKEVEN POINT The break-even point of the project including cost of finance when it starts to operate at full capacity (year ) is estimated by using income statement projection. 24,410,000

BEP = Fixed Cost / (price per unit- Variable Cost per unit) = 9000−1544.07 = 3273.87 units 3273.87 kg of lemongrass oil has to be sold for the revenues of the business to equal its total costs. 13.12 PAY-BACK PERIOD The investment cost and income statement projection are used to project the pay-back period. The project’s initial investment will be fully recovered within 3 years.

13.13 ECONOMIC BENEFITS The project can create employment for 50 persons. In addition to supply of the domestic needs, the project will generate up to N 77,000,000 in revenue. The establishment of such factory will have a foreign exchange saving effect to Nigeria by substituting the current imports.