ethylene glycol

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1 CHAPTER I INTRODUCTION 1.1 HISTORY: Ethylene Glycol (1, 2 ethanediol), HOCH 2 CH 2 OH usually called glycol is the simplest Diol. Diethylene glycol and Triethylene glycol are Oligomers of Mono ethylene glycol. Ethylene glycol was first prepared by Wurtz in 1859; treatment of 1,2 dibromoethane with silver acetate yielding ethylene glycol diacetate via saponification with potassium hydroxide and in 1860 from the hydration of ethylene oxide. There to have been no commercial manufacture or application of ethylene glycol prior to World War-I when it was synthesized from ethylene dichloride in Germany and used as substituted for glycerol in the explosives industry and was first used industrially in place of glycerol during World War I as an intermediate for explosives (ethylene glycol dinitrate) but has since developed into a major industrial product. The use of ethylene glycol as an antifreeze for water in automobile cooling systems was patented in the United States in 1917, but this commercial application did not start until the late 1920s. The first inhibited glycol antifreeze was put on the market in 1930 by National Carbon Co. (Now Union Carbide Corp.) under the brand name “prestone”. Carbide continued to be essentially the sole supplier until the late 1930s. In 1940 DuPont started up an ethylene glycol plant in Belle, West Virginia based on its new formaldehyde methanol process. In 1937 Carbide started up the first plant based on Lefort’s process for vapor phase oxidation of ethylene oxide. The worldwide capacity for production of Ethylene Glycol via hydrolysis of ethylene oxide is estimated to be 7×10 6 ton/annum [1, 2]. 1.2 CHEMISTRY: Compound contains more than one oly group is called Polyhydric Alcohol (Dihydric alcohol) or polyols (Diols). Diols are commonly known as Glycols, since they have a sweet taste (Greek, glycys= Sweet).

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Ethylene Glycol

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  • 1

    CHAPTER I

    INTRODUCTION

    1.1 HISTORY:

    Ethylene Glycol (1, 2 ethanediol), HOCH2CH2OH usually called glycol is the

    simplest Diol. Diethylene glycol and Triethylene glycol are Oligomers of Mono

    ethylene glycol.

    Ethylene glycol was first prepared by Wurtz in 1859; treatment of 1,2 dibromoethane

    with silver acetate yielding ethylene glycol diacetate via saponification with

    potassium hydroxide and in 1860 from the hydration of ethylene oxide. There to have

    been no commercial manufacture or application of ethylene glycol prior to World

    War-I when it was synthesized from ethylene dichloride in Germany and used as

    substituted for glycerol in the explosives industry and was first used industrially in

    place of glycerol during World War I as an intermediate for explosives (ethylene

    glycol dinitrate) but has since developed into a major industrial product.

    The use of ethylene glycol as an antifreeze for water in automobile cooling systems

    was patented in the United States in 1917, but this commercial application did not

    start until the late 1920s. The first inhibited glycol antifreeze was put on the market in

    1930 by National Carbon Co. (Now Union Carbide Corp.) under the brand name

    prestone.

    Carbide continued to be essentially the sole supplier until the late 1930s. In 1940

    DuPont started up an ethylene glycol plant in Belle, West Virginia based on its new

    formaldehyde methanol process. In 1937 Carbide started up the first plant based on

    Leforts process for vapor phase oxidation of ethylene oxide.

    The worldwide capacity for production of Ethylene Glycol via hydrolysis of ethylene

    oxide is estimated to be 7106 ton/annum [1, 2].

    1.2 CHEMISTRY:

    Compound contains more than one oly group is called Polyhydric Alcohol (Dihydric

    alcohol) or polyols (Diols). Diols are commonly known as Glycols, since they have a

    sweet taste (Greek, glycys= Sweet).

  • 2

    Dihydric alcohols because compounds contain two OH groups on one carbon are

    seldom encountered. This is because they are unstable and undergo spontaneous

    decomposition to give corresponding carbonyl compound and water.

    Figure-1[10]

    According to IUPAC system of nomenclature, IUPAC name of glycol is obtained by

    adding suffix Diol to the name of parent alkanes.

    HO OH H H H H

    H--C---C--H HO--C---C--OH H--C---C--H

    H H H H HO OH

    1, 2 Glycol 1, 3 Glycol 1, 4 Glycol

    (- Glycol) (- Glycol) (- Glycol)

    Glycols are Diols. Compounds containing two hydroxyl groups attached to separate

    carbon in an aliphatic chain. Although glycols may contain heteroatom can be

    represented by the general formula C2nH4nOn-1(OH) 2. [3, 4]

    Formula Common name IUPAC name

    CH2OHCH2OH Ethylene Glycol Ethane-1, 2-Diol

    1.3 USES:

    The following is a summary of the major uses of ethylene glycol:

    1.3.1 Antifreeze

    A major use of ethylene glycol is as antifreeze for internal combustion

    engines. Solutions containing ethylene glycol have excellent heat transfer properties

    and higher boiling points than pure water. Accordingly, there is an increasing

    tendency to use glycol solutions as a year-round coolant. Ethylene glycol solutions are

  • 3

    also used as industrial heat transfer agents.

    Mixtures of ethylene glycol and propylene glycol are used for defrosting and

    de-icing aircraft and preventing the formation of frost and ice on wings and fuselages

    of aircraft while on the ground. Ethylene glycol-based formulations are also used to

    de-ice airport runways and taxiways as de-icing agent.

    Asphalt-emulsion paints are protected by the addition of ethylene glycol

    against freezing, which would break the emulsion. Carbon dioxide pressurized fire

    extinguishers and sprinkler systems often contain ethylene glycol to prevent freezing.

    1.3.2 Explosives

    Ordinary dynamite will freeze at low temperatures and cannot then be

    detonated. Ethylene glycol dinitrate, which is an explosive itself, is mixed with

    dynamite to depress its freezing point and make it safer to handle in cold weather.

    Mixtures of glycerol and ethylene glycol are nitrated in the presence of

    sulfuric acid to form solutions of nitroglycerin in ethylene glycol dinitrate, which are

    added to dynamite in amounts ranging from 25 to 50%.

    1.3.3 Polyester Fibers

    The use of ethylene glycol for fibers is becoming the most important consumer

    of glycol worldwide. These fibers, marketed commercially under various trade names

    like Dacron, Fortel, Kodel, Terylene etc are made by the polymerization of ethylene

    glycol with BisHydroxyEthyl Terephthalate (BHET).

    These Polyester fibers are used for recyclable bottles.

    1.3.4 Resins

    Polyester resins made from maleic and phthalic anhydrides, ethylene glycol,

    and vinyl-type monomers have important applications in the low-pressure

    lamination of glass fibers, asbestos, cloth and paper.

    Polyester-fiberglass laminates are used in the manufacture of furniture,

    automobile bodies, boat hulls, suitcases and aircraft parts. Alkyd-type resins are

    produced by the reaction of ethylene glycol with a dibasic acid such as o-phthalic,

    maleic or fumaric acid. These resins are used to modify synthetic rubbers, in

    adhesives, and for other applications.

    Alkyds made from ethylene glycol and phthalic anhydride is used with similar

    resins based on other polyhydric alcohols, such as glycerol or pentaerythritol in the

    manufacture of surface coatings. Resin esters made with ethylene glycol are used as

  • 4

    plasticizers in adhesives, lacquers and enamels.

    1.3.5 Hydraulic Fluids

    Ethylene glycol is used in hydraulic, brake and shock absorber fluids to help

    dissolve inhibitors, prevent swelling of rubber, and inhibit foam formation.

    Hydro lubes, which are water-based mixtures of polyalkylene glycols and

    presses and die casting machines, and in airplane hydraulic systems because of their

    relatively low viscosity at high pressure. An added advantage of primary importance

    is that these hydro lubes are inflammable.

    1.3.6 Capacitors

    Ethylene glycol is used as a solvent and suspending medium for ammonium

    perborate, which is the conductor in almost all electrolytic capacitors.

    Ethylene glycol, which is of high purity (iron and chloride free), is used

    because it has a low vapor pressure, is non-corrosive to aluminum and has excellent

    electrical properties.

    1.3.7 Other uses

    Ethylene glycol is used to stabilize water dispersions of urea-formaldehyde

    and melamine-formaldehyde from gel formation and viscosity changes. It is used as

    humectants (moisture retaining agent) for textile fibers, paper, leather and

    adhesives and helps make the products softer, more pliable and durable.

    An important use for ethylene glycol is as the intermediate for the

    manufacture of Glyoxal, the corresponding dialdehyde. Glyoxal is used to treat

    polyester fabrics to make them permanent press.

    Ethylene glycol derivatives mainly ether and ester are used as absorption

    fluids, Diethylene Glycol is used as a softener (Cork, adhesives, and paper) dye

    additive (Printing and stamping), deicing agent for runway & air craft, drying agent

    for gases (natural gas).

    Triethylene glycol is used for same purpose as Diethylene glycol.

    Poly (ethylene glycol) with varying molecular masses and numerous uses in

    Pharmaceutical industry (Ointments, Liquids and tabletting) and cosmetic industry

    (cream lotion, pastes, cosmetic sticks, soaps). They are also used in textile industry

    (Cleaning and dyeing agents), in Rubber industry (lubricating & Mold parting agents),

    in ceramics (bonding agents and plasticizers).[3,4]

  • 5

    CHAPTER II

    PROPERTIES

    2.1 PHYSICAL PROPERTIES:

    Monoethylene glycol and its lower polyglycols are clear, odorless, colorless,

    syrupy liquid with a sweet taste.

    It is a hygroscopic liquid completely miscible with many polar solvents, such

    as water, alcohols, glycol ethers, and acetone.

    Its solubility is low however in non polar solvents, such as benzene, toluene,

    dichloroethane, and chloroform. It is miscible in ethanol in all proportion but

    insoluble in ether, completely miscible with many polar solvents, water, alcohols,

    glycol ethers and acetone. Its solubility is low, however in nonpolar solvents, such as

    benzene, toluene, dichloromethane and chloroform.

    It is a toxic as methyl alcohol when taken orally.

    Ethylene glycol is difficult to crystallize, when cooled; it forms a highly

    viscous, super-cooled mass that finally solidifies to produce a glasslike substance.

    The widespread use of ethylene glycol as an antifreeze is based on its ability

    to lower freezing point when mixed with water. [3, 4]

    Table 2.1 Physical Properties. [1, 2]

    Sr.

    no.

    Physical Properties

    1. Molecular formula C2H6O2

    2. Molecular weight 62

    3. Specific gravity at 20/20oC 1.1135

    4. Boiling point oC at 101.3 KPa 197.60

    5. Freezing point oC -13

    6. Heat of vaporization at 101.3 KPa; KJ/mol 52.24

    7. Heat of combustion (25oC) MJ/mol 19.07

  • 6

    8. Critical Temp. oC 372

    9. Critical pressure, KPa 6513.73

    10. Critical volume, L/mol 0.1861

    11. Refractive index, 1.4318

    12. Cubic expansion coefficient at 20 oC, K

    -1 0.62 10

    -3

    13. Viscosity at 20oC; mPa S 19.83

    14. Liquid density (20oC) gm/cm

    3 1.1135

    15. Flash point, oC 111

    16. Auto-ignition temp in air oC 410

    17. Flammability limits in air; vol%

    Upper 53

    Lower 3.2

    2.2 CHEMICAL PROPERTIES:

    Ethylene Glycol contains two primaries OH groups. Its chemical reactions are

    therefore, those of primary alcohols twice over. Generally, one OH group is attacked

    completely before other reacts.

    2.1.1 Dehydration

    With Zinc chloride, it gives Acetaldehyde

    HOCH2CH2OH CH3CHO + H2O

    (Ethylene Glycol) (Acetaldehydes)

    On heating alone at 500 oC, it gives Ethylene oxide.

    With H2SO4 it gives dioxane which is important industrial solvent.

    2.1.2 Oxidation

    Ethylene glycol is easily oxidized to form a number of aldehydes and carboxylic acids

    by oxygen, Nitric acid and other oxidizing agents.

  • 7

    The typical products derived from alcoholic functions are Glycolaldehyde

    (HOCH2CHO), Glycolic acid (HOCH2COOH), Glyoxylic acid (HCO-COOH), Oxalic

    Acid (HOOCCOOH), formaldehyde & formic acid.

    With HNO3 oxidation it yields nos. of substance as one or both primary OH

    groups may be oxidized to aldehydes and these carboxylic groups.

    HNO3 [O] [O]

    HOCH2CH2OH HOCH2CHO HOCH2CH2COOH CHOCOOH

    (Ethylene Glycol) (Glycol aldehydes) (Glycolic acid) (Glyoxylic acid)

    [O]

    HOOC-COOH

    (Oxylic acid)

    [O]

    HNO3 [O] [O]

    HOCH2CH2OH HOCH2CHO CHOCHO CHOCOOH

    (Ethylene Glycol) (Glycol aldehydes) (Glyoxal) (Glyoxylic acid)

    2.1.3 Other reactions

    The hydroxyl groups on glycols undergo the usual alcohol chemistry giving a wide

    variety of possible derivatives. Hydroxyls can be converted to aldehydes, alkyl

    halides, amides, amines, azides, carboxylic acids, ethers, mercaptans, nitrate esters,

    nitriles, nitrite esters, organic esters, peroxides, phosphate esters, and sulfate esters.

    Reaction with sodium at 50 oC to form monoalkoxide and dialkoxide when

    temperature is raised.

    Na at 50 oC Na at 160

    oC

    HOCH2CH2OH HOCH2CH2ONa NaOCH2CH2ONa

    (Ethylene Glycol) (Mono Alkoxide) (Di Alkoxide)

    Reaction with Phosphorus pentahalide (PCl5) it first gives Ethylene

    chlorohydrins and then 1, 2 dichloroethane. PBr5 reacts in same way.

    PCl5 PCl5

    HOCH2CH2OH HOCH2CH2Cl ClCH2CH2Cl

    (Ethylene Glycol) (Ethylene chlorohydrins) (1, 2-Dicholorochlorohydrins)

    With Phosphorus trihalide (PBr3) to form responding dihalide

    PBr3 PBr3

    HOCH2CH2OH HOCH2CH2Br BrCH2CH2Br

  • 8

    (Ethylene Glycol) (Ethylene Bromohydrins) (1, 2-Dibromohydrins)

    With HCl in two step reaction, form ethylene chlorohydrins at 160oC and

    second forms 1, 2 dichloroethane at 200oC.

    160 oC 200

    oC

    HOCH2CH2OH HOCH2CH2Cl ClCH2CH2Cl

    (Ethylene Glycol) (Ethylene chlorohydrins) (1, 2-Dicholorochlorohydrins)

    The largest commercial use of ethylene glycol is its reaction with dicarboxylic

    acids (1) to form linear polyesters. Poly (Ethylene Terephthalate) (PET) (2) is

    produced by esterification of teraphthalic acid to form BisHydroxyEthyl

    Terephthalate (BHET) (3). BHET polymerizes in a transesterification reaction

    catalyzed by antimony oxide to form PET.

    2HOCH2CH2OH

    +

    HOOC COOH + HOCH2CH2OOC COOCH2CH2OH

    (1) (2)

    + HOCH2CH2OH

    Ethylene glycol esterification of BHET is driven to completion by heating and

    removal of the water formed. PET is also formed using the same chemistry starting

    with dimethyl Terephthalate and ethylene glycol to form BHET also using an

    antimony oxide catalyst.

    Ethylene glycol also produces 1, 4-dioxane by acid-catalyzed dehydration to

    Diethylene glycol followed by cyclization. Cleavage of Triethylene and higher

    glycols with strong acids also produces 1, 4-dioxane by catalyzed ether hydrolysis

    with subsequent cyclization of the Diethylene of the Diethylene glycol fragment.

    Diethylene glycol condenses with primary amines of form cyclic structures, e.g.,

    methylamine reacts with Diethylene glycol to produce N-methylmorpholine.

    Sb2O3OOC*H COOCH2CH2 *H

    n

    (3)

  • 9

    HOCH2CH2OCH2CH2OH CH3NH2 O N CH3 + 2H2O (6)+

    Ketones and aldehydes react with ethylene glycol under acidic conditions to

    Form 1, 3-dioxolanes cyclic ketals and acetals.

    HOCH2CH2OH + RCOR+

    H+O

    O

    R'

    R

    H2O+ (7)

    Ethylene glycol reacts with ethylene oxide to form di, tri, tetra and

    polyethylene glycols.

    Ethylene glycols is stable compound, but special care is required when

    ethylene glycol is heated at a higher temperature in presence of NaOH, which is

    exothermic reaction at temperature above 250 oC of evolution of H2 (-90 to -160

    KJ/Kg).[1,3,4]

  • 10

    CHAPTER III

    LITERATURE SURVEY

    The literature survey has been done with an aim to obtain information concerning

    Ethylene Glycol and its production from number of sources. Such information sources

    include chemical abstracts, periodicals and books on chemical technology,

    handbooks, encyclopedias and internet websites. The literature survey yielded a lot of

    information on Ethylene Glycol. A brief review of information obtained from the

    literature survey is presented hereafter.

    During the project many Journals, Manuals and Hand book have been sited The

    manufacturing process have been taken from Chemical Engineering Journal

    107(2005), 199-204. The selectivity and other process parameters have been taken

    from Chemical Engineering Journal 107(2005), 199-204. The demand growths,

    Major producer in India & World have been taken from Internet.

    3.1 DERIVATIVES OF MONO ETHYLENE GLYCOL:

    In addition to Oligomers ethylene glycol dervative classes include monoethers,

    diethers, esters, acetals, and ketals as well as numerous other organic and

    organometalic molecules. These derivatives can be of ethylene glycol, Diethylene

    glycol, or higher glycols and are commonly made with either the parent glycol or with

    sequential addition of ethylene oxide to a glycol alcohol, or carboxylic acid forming

    the required number of ethylene glycol submits.

    3.1.1 Diethylene Glycol:

    Physical properties of Diethylene glycol are listed in Table. Diethylene glycol is

    similar in many respects to ethylene glycol, but contains an ether group. It was

    originally synthesized at about the same time by both Lourenco and Wurtz in 1859,

    and was first marketed, by Union Carbide in 1928. It is a co product (9 - 10%) of

    ethylene glycol produced by ethylene oxide hydrolysis. It can be made directly by the

    reaction of ethylene glycol with ethylene oxide, but this route is rarely used because

    more than an adequate supply is available from the hydrolysis reaction.

    Manufacture of unsaturated polyester resins and polyols for polyurethanes consumes

    45% of the Diethylene glycol. Approximately 14% is blended into antifreeze.

    Triethylene glycol from the ethylene oxide hydrolysis does not meet market

  • 11

    requirements, which leads to 12% of the Diethylene glycol being converted with

    ethylene oxide to meet this market need. About 10% of Diethylene glycol is converted

    to morpholine. Another significant use is natural gas dehydration, which uses 6%. The

    remaining 13% is used in such applications as plasticizers for paper, fiber finishes,

    and compatiblizers for dye and printing ink components, latex paint, antifreeze, and

    lubricants in a number of applications.

    3.1.2 Triethylene Glycol:

    Triethylene glycol is a colorless, water-soluble liquid with chemical properties

    essentially identical to those of Diethylene glycol. It is a co product of ethylene glycol

    produced via ethylene oxide hydrolysis. Significant commercial quantities are also

    produced directly by the reaction of ethylene oxide with the lower glycols.

    Triethylene glycol is an efficient hygroscopicity agent with low volatility, and about

    45% is used as a liquid drying agent for natural gas. Its use in small packaged plants

    located at the gas wellhead eliminates the need for line heaters in field gathering

    systems as a solvent (11 %) Triethylene glycol is used in resin impregnants and other

    additives, steam-set printing inks, aromatic and paraffinic hydrocarbon separations,

    cleaning compounds, and cleaning poly (ethylene Terephthalate) production

    equipment. The freezing point depression property of Triethylene glycol is the basis

    for its use in heat-transfer fluids.

    Approximately 13% Triethylene glycol is used in some form as a vinyl plasticizer.

    Triethylene glycol esters are important plasticizers for poly (vinyl butyral) resins,

    Nitrocellulose lacquers, vinyl and poly (vinyl chloride) resins, poly (vinyl acetate) and

    synthetic rubber compounds and cellulose esters. The fatty acid derivatives of

    Triethylene glycol are used as emulsifiers, emulsifiers, and lubricants. Polyesters

    derived from Triethylene glycol are useful as low pressure laminates for glass fibers,

    asbestos, cloth, or paper. Triethylene glycol is used in the manufacture of alkyd resins

    used as laminating agents and adhesives.

    3.1.3 Tetra ethylene Glycol:

    Tetra ethylene glycol has properties similar to Diethylene and Triethylene glycols and

    may be used preferentially in applications requiring a higher boiling point, higher

    molecular weight, or lower hygroscopicity.

  • 12

    Tetra ethylene glycol is miscible with water and many organic solvents. It is a

    humectants that, although less hygroscopic than the lower members of the glycol

    series, may find limited application in the dehydration of natural gases. Other

    possibilities are in moisturizing and plasticizing cork, adhesives, and other substances.

    Tetra ethylene glycol may be used directly as a plasticizer or modified by

    esterification with fatty acids to produce plasticizers. Tetra ethylene glycol is used

    directly to plasticize separation membranes, such as silicone rubber, poly (Vinyl

    acetate), and cellulose triacetate. Ceramic materials utilize tetra- ethylene glycol as

    plasticizing agents in resistant refractory plastics and molded ceramics. It is also

    employed to improve the physical properties of cyanoacrylate and polyacrylonitrile

    adhesives, and is chemically modified to form Polyisocyanate, polymethacrylate, and

    to contain silicone compounds used for adhesives.

    Tetra ethylene glycol has found application in the separation of aromatic

    hydrocarbons from nonromantic hydrocarbons (BTX extraction). In general, the

    critical solution temperature of a binary system, consisting of a given alkyl-substituted

    aromatic hydrocarbon and tetra ethylene glycol, is lower than the critical solution

    temperature of the same hydrocarbon with Triethylene glycol and is considerably

    lower than the critical solution temperature of the same hydrocarbon with Diethylene

    glycol. Hence, at a given temperature, tetra ethylene glycol tends to exact the higher

    alkyl benzenes at a greater capacity than a lower polyglycols.

    3.2 STORAGE AND TRANSPORTATION:

    Pure anhydrous ethylene glycol is not aggressive toward most metals and plastics.

    Since ethylene glycol also has a low vapor pressure and is non caustic. It can be

    handled with out any problems: it is transported in railroad tank cars, tank trucks, and

    tank ships. Tanks are usually made of steel: high grade materials are only required for

    special quality requirements. Nitrogen blanketing can protect ethylene glycol against

    oxidation.

    At ambient temperature, aluminum is resistant to pure glycol. Corrosion occurs,

    however, above 100oC and hydrogen is evolved. Water air and acid producing

    impurities (aldehydes) accelerate this reaction. Great care should be taken when

    phenolic resins are involved, since they are not resistance to ethylene glycol.

  • 13

    3.3 SHIPPING DATA FOR ETHYLENE GLYCOL:

    Weight per Gallon at 20C 9.29 lb

    Coefficient of Expansion at 55C 0.00065

    Flash Point, Tag Closed Cup 260F

    Net Contents and Type of Container

    1Gallon Tin Can 9.0 lb

    5Gallon DOT 17E, Pail 47 lb

    55Gallon DOT 17E, Drum 519 lb

    3.4 ENVIRONMENTAL PROTECTION AND ECOLOGY:

    Ethylene glycol is readily biodegradable, thus disposal of waste water containing this

    compound can proceed without major problems. The high LC 50value of over 10000

    mg/lit account for its low water toxicity.

    3.5 PRODUCT SAFETY:

    When considering the use of ethylene glycol in any particular application, review and

    understand our current Material Safety Data Sheet for the necessary safety and

    environmental health information. Before handling any products you should obtain

    the available product safety information from the suppliers of those products and take

    the necessary steps to comply with all precautions regarding the use of ethylene

    glycol. No chemical should be used as or in a food, drug, medical device, or cosmetic,

    or in a product process in which it may come in contact with a food, drug, medical

    device, or cosmetic until the user has determined the suitability of the use. Because

    use conditions and applicable laws may differ from one location to another and may

    change with time, Customer is responsible for determining whether products and the

    information are appropriate for Customers use [5, 6]

  • 14

    CHAPTER IV

    MARKET SURVEY

    4.1 ECONOMIC ASPECTS:

    Ethylene glycol is one of the major products of the chemical industry. Its economic

    importance is founded on its two major commercial uses as antifreeze and for fiber

    production. Since Ethylene glycol is currently produced exclusively from ethylene

    oxide production plant are always located close to plant that produce ethylene oxide.

    The proportion of ethylene oxide that is converted to Ethylene glycol depends on

    local condition, such as market situation and transport facilities. About 60% of total

    world production is converted to ethylene glycol.

    About 50% of the ethylene glycol that is used as antifreeze. Another 40% is used in

    fiber industry. Consequently the ethylene glycol demand is closely connected to the

    development of these two sectors In view of the increasing price of crude oil,

    alternative production method based on synthesis gas is likely to become more

    important and increasing competitive.

    4.2 LEADING PRODUCERS IN WORLD:

    BASF, Geismer, La. (America).

    DOW, Plaquemine, La .(America)

    OXYPETROCHEMICALS, Bayport, Tex .(America)

    PD Glycol ,Beaumont, Tex. (America)

    SHELL, Geismer,La. (America)

    TEXACO ,Port Neches, Tex.(America)

    UNION CARBIDE, Taft,La.(America)

    BP Chemicals, Belgium, (West Europe).

    IMPERIAL Chemicals Ind. United Kingdom, (West Europe)

    BPC (NAPTHACHIMIE),France , (West Europe)

    STATE COMPLEXES ,USSR, (West Europe)

    PAZINKA, Yugoslavia, (West Europe)

    EASTERN PETROCHEMICAL CO. Saudi Arabia, (Middle East)

    National Organic Chemical, India, (Asia).

    Mitsubishis Petrochemicals, (Japan)

  • 15

    4.3 LEADING PRODUCER IN INDIA:

    India Glycol, Uttaranchal (North India).

    Reliance Industries Ltd. Hazira (Gujarat).

    Indian Petrochemical Corporation Ltd, Baroda (Gujarat).

    NOCIL, Thane.

    SM Dye chem. Pune.

    4.4 MEG PRICE TREND:

    Table 4.1 MEG Price Trend

    Sr. No. Year Month Price(US$/MT)

    1. 2004 November 1095

    2. December 988

    3. 2005 January 1045

    4. February 1095

    5. March 1095

    6. April 971

    7. May 734

    8. June 736

    9. July 808

    10. August 836

    11. September 883

    12. October 883

    13. November 1st week 830

    14. 2nd

    week 822

    4.5 DEMAND SUPPLY BALANCE (IN KT):

    Table 4.2 Demand supply balance (In KT)

    MEG 2002 2003 2004 2005 2006

    Capacity 590 615 654 830 830

    Production 548 647 691 833 830

    Imports 11 64 106 103 90

    Exports 8 29 104 133 60

    Demand 551 682 750 803 860

    Demand Growth % 24% 10% 7% 7%

  • 16

    4.6 QUALITY SPECIFICATION:

    Since ethylene glycol is produce in relatively high purity difference in quality are not

    accepted. The directly synthesized product meets high quality demands (fiber grade).

    The ethylene glycol produce in the wash water that is use during ethylene oxide

    production is normally of a somewhat inferior quality (antifreeze grade). The quality

    specifications for mono ethylene glycol are compiling in table-2. [5, 6]

    Table 4.3 Quality Specification OF Ethylene Glycol

    DESCRIPTION FIBER GRADE INDUSTRIAL GRADE

    Color, Pt-Co, max 5 10

    Suspended matter Substantially free Substantially free

    Diethylene glycol, wt.% max 0.08 0.6

    Acidity, as acetic acid, wt%

    max

    0.005 0.02

    Ash, wt% max 0.005 0.005

    Water, wt% max 0.08 0.3

    Iron, ppm wt max 0.07 0.05

    Chlorides, ppm wt max

    Distillation range, ASTM at

    760mm Hg:

    IBP, C min 196 196

    DP, C max 200 199

    Odor Practically none

    UV transmittance, % min at:

    220 nm 70 70

    250 nm 90

    275 nm 90 95

    350 nm 98 99

    Specific gravity, 20/20C 1.1151-1.1156 1.1151-1.1156

    Water solubility, 25C Completely miscible

  • 17

    CHAPTER V

    PROCESS SELECTION AND DESCRIPTION

    5.1 MANUFACTURING PROCESSES:

    Up to the end of 1981, only two processes for manufacturing ethylene glycol have

    been commercialized. The first, the hydration of ethylene oxide, is by far the most

    important, and from 1968 through 1981 has been the basis for all of the ethylene

    glycol production.

    Manufacturing process involves laboratory methods and industrial methods.

    5.1.1 Laboratory methods: [3, 4]

    By passing Ethylene in to cold dilute Alkaline permanganate solution i.e.

    Oxidation of Ethylene to Glycol

    By hydrolysis of Ethylene Bromide by boiling under reflux with aqueous

    sodium carbonate solution. This reaction mixture is refluxed till an oily globule of

    ethylene bromide disappears. The resulting solution is evaporated on a water bath and

    semi solid residue is extracted with ether-alcohol mixture. Glycol is recovered from

    solution by distillation. The best yield of glycol (83-84%) can be obtained by heating

    ethylene bromide with potassium acetate in Glacial acetic acid.

    Ethylene glycol can be produced by an electrohydrodimerization of

    formaldehyde.

    An early source of glycols was from hydrogenation of sugars obtained from

    formaldehyde condensation. Selectivity to ethylene glycol was low with a number of

    other glycols and polyols produced. Biomass continues to be evaluated as a feedstock

    for glycol production.

    5.1.2 Industrial methods: [1, 2, 7, 8]

    The production of ethylene glycol by the hydration of ethylene oxide is

    simple, and can be summarized as follows: ethylene oxide reacts with water to form

    glycol, and then further reacts with ethylene glycol and higher homologues in a series

    of consecutive reactions as shown in the following equations.

  • 18

    +

    O

    CH2 H2OH2C CH2

    OH

    OH

    +

    O

    CH2 H2C CH2

    OH

    OH

    H2C CH2

    OH

    O CH2

    OH

    CH2

    Ethylene OxideEthylene Glycol

    Diethylene Glycol

    H2C

    H2C

    +

    O

    CH2H2C H2C CH2

    OH

    O CH2

    OH

    CH2

    H2C CH2

    OH

    O CH2

    OH

    CH2 CH2 O CH2

    Triethylene Glycol

    Ethylene oxide hydrolysis proceeds with either acid or base catalysis or uncatalyzed

    in neutral medium. Acid-catalyzed hydrolysis activates the ethylene oxide by

    protonation for the reaction with water. Base-catalyzed hydrolysis results in

    considerably lower selectivity to ethylene glycol. The yield of higher glycol products

    is substantially increased since anions of the first reaction products effectively

    compete with hydroxide ion for ethylene oxide. Neutral hydrolysis (pH 6-10),

    conducted in the presence of a large excess of water at high temperatures and

    pressures, increases the selectivity of ethylene glycol to 89-91%. In all these ethylene

    oxide hydrolysis processes the principal byproduct is Diethylene glycol. The higher

    glycols, i.e., Triethylene and Triethylene glycols, account for the remainder.

    Although catalytic hydration of ethylene oxide to maximize ethylene glycol

    production has been studied by a number of companies with numerous materials

    patented as catalysts, there has been no reported industrial manufacture of ethylene

    glycol via catalytic ethylene oxide hydrolysis. Studied catalyst include sulfonic acids,

    carboxylic acids and salts, cation-exchange resins, acidic zeolites, halides, anion-

  • 19

    exchange resins, metals, metal oxide and metal salts. Carbon dioxide as a co catalyst

    with many of the same materials has also received extensive study.

    Ethylene glycol was commercially produced in the United States from

    ethylene chlorohydrins which was manufactured from ethylene and hypochlorous

    acid. Chlorohydrins can be converted directly to ethylene glycol by hydrolysis with a

    base, generally caustic or caustic/bicarbonate mix. An alternative production method

    is converting chlorohydrins to ethylene oxide with subsequent hydrolysis.

    CH2 CH2 + HOCl HOCH2CH2Cl (8)

    + NaOH (9)HOCH2CH2Cl HOCH2CH2OH NaCl+

    + Ca(OH)2 (10)HOCH2CH2Cl CH2 NaCl+

    O

    CH2

    + (11)CH2

    O

    CH2 H2O HOCH2CH2OH

    Du Pont commercially produced ethylene glycol from carbon monoxide,

    methanol, hydrogen, and formaldehyde until 1968 at Belle, West Virginia. The

    process consisted of the reaction of formaldehyde, water, and carbon monoxide with

    an acid catalyst to form glycolic acid. The acid is esterified with methanol to produce

    methyl glycolate. Subsequent reduction with hydrogen over a chromate catalyst yields

    ethylene glycol and methanol. Methanol and formaldehyde were manufactured on site

    from syngas.

    + CH2O (12)CO HOOCCH2OH NaCl++ H2OH+

    + CH3OH (13)CH3OOCCH2OH +HOOCCH2OH H2O

    + H2 (14)CH3OOCCH2OH +HOCH2CH2OH CH3OHCr2O3

    Coal was the original feedstock for syngas at Belle; thus ethylene glycol was

    commercially manufactured from coal at one time. Ethylene glycol manufacture from

    syngas continues to be pursued by a number of researchers.

  • 20

    Ethylene glycol can be produced from acetoxylation of ethylene. Acetic acid,

    oxygen, and ethylene react with a catalyst to form the glycol mono and diacetate.

    Catalysts can be based on palladium, selenium, tellurium, or thallium. The esters are

    hydrolyzed to ethylene glycol and acetic acid. The net reaction is ethylene plus water

    plus oxygen to give ethylene glycol. This technology has several issues which have

    limited its commercial use.

    + O2 (15)CH3COOH CH3COOCH2OOCCH3Te2Br2CH2 CH2 +

    + (16)CH3COOCH2CH2OH 2 HOCH2CH2OH3 H2O

    CH3COOCH2CH2OOCCH3 3 CH3COOH+ The catalysts and acetic are highly corrosive, requiring expensive construction

    materials. Trace amounts of ethylene glycol mono-and diacetates are difficult to

    separate from ethylene glycol limiting the glycols value for polyester manufacturing.

    This technology (Halcon license) was practiced by Oxirane in 1978 and j1979 but was

    discontinued due to corrosion problems.

    Ethylene glycol can be manufactured by the transesterification of ethylene

    carbonate. A process based on the reaction of ethylene carbonate with methanol to

    give dimethyl carbonate and ethylene glycol is described in a Texaco patent; a general

    description of the chemistry has also been published.

    O O

    C

    O

    + 2 CH3OHZr2Cl4

    HOCH2CH2OH + CO(CH3O)2 (18)

    Selectivity to ethylene glycol are excellent with little Diethylene glycol or higher

    glycols produced. A wide range of catalysts may be employed including ion exchange

    resins, zirconium and titanium compounds, tin compounds, phosphines, acids and

    bases. The process produces a large quantity of dimethyl carbonate which would

    require a commercial outlet.

    Oxalic acid produced from syngas can be esterified and reduced with

    hydrogen to form ethylene glycol with recovery of the esterification alcohol.

    Hydrogenation requires a copper catalyst giving 100% conversion with selectivity to

    ethylene glycol of 95%.

  • 21

    + 2 ROH (20)ROOCCOOR +HOOCCOOH 2 H2O

    ROOCCOOR + 4 H2Cu

    HOCH2CH2OH + 2 ROH (21)

    The Teijin process, which has not been commercialized to date, produces

    ethylene glycol by the reaction of ethylene with thallium salts in the presence of water

    and chloride or bromide ions. The major by-product in the reaction is acetaldehyde.

    A redox metal compound (such as copper) oxidizable with molecular oxygen is added

    to the reaction medium to permit the regeneration of the thallium salt.

    The DuPont process, based on feeds derived from synthesis gas (CO and

    formaldehyde), became economically obsolete because of low-priced ethylene. With

    the high price of oil and natural gas, there has been increasing interest in coal

    gasification to produce fuel and also synthesis gas for petrochemical manufacture. In

    1976, Union Carbide announced that a process for the production of ethylene glycol

    from synthesis gas was being developed for commercialization in the early 1980.The

    proposed reaction was based on using a rhodium-based catalyst in tetrahydrofuran

    solvent at 190-230C and high pressure (3400 atm). The equi molar mixture of CO

    and H2 would be converted mainly to ethylene glycol and by-product glycerol and

    propylene oxide. Methanol, methyl formate, and water would also be produced.[10]

    5.2. PROCESS SELECTION:

    The process selection is based on different advantages and parameters of the industrial

    methods.

    5.2.1 Comparison of different Processes:

    Hydration of ethylene oxide is an industrial approach to glycols in general, and

    ethylene glycol in particular. Ethylene glycol is one of the major large-scale products

    of industrial organic synthesis, with the world annual production of about 15.3

    million t/yr in 2000. Hydration of ethylene oxide proceeds on a serial-to-parallel route

    with the formation of homologues of glycol:

  • 22

    Table 5.1 Comparison of different Processes

    SR.

    NO

    PROCESSES PARAMETER

    CATALYST ADVANTAGES/DISA

    DVANTAGES

    1. Hydrolysis of

    Ethylene Oxide

    1) Non- catalytic

    Yield : 98%

    Selectivity: 98%

    Temp:105oC

    Pressure :

    1.5MPa

    2) catalytic:

    Yield : 95%

    Selectivity: 90%

    Temp:200oC

    Pressure :

    1-30 bar

    1)Non

    Catalytic

    2) Catalytic:

    Sulfonic acids,

    Carboxylic

    acids and salts,

    Ion-exchange

    resins, Acidic

    zeolites,

    halides, Metal

    oxide and

    Metal salts.

    Use large excess water

    to increase the yield

    which leads to high

    energy consumption

    1) Use less excess water

    which leads to low

    energy consumption

    2) High yield &

    selectivity

    3) permit use of low

    temp & pressure

    4) Acid catalyst makes

    the reaction solution

    highly corrosive.

    2. Ethylene Glycol

    from Ethylene

    chlorohydrins

    Yield :50%

    Selectivity: 75%

    Non Catalytic very low yield &

    selectivity

    very costly

    3. Ethylene glycol

    from

    CO,H2,CH3OH

    &

    Formaldehyde

    Yield : 90-95%

    Temp: 200oC

    Pressure:

    100atm

    Cromate

    Catalyst

    High pressure

    process

    Discontinued now a

    day

    Low selectivity

    4. Ethylene glycol

    from ethylene

    carbonate

    Yield :98%

    Selectivity: 95%

    Temp:180oC

    Pressure:13bar

    Alkali halide

    or ammonium

    salt.

    Give high yield and

    selectivity

    Utility saving

    Extra purification

    cost

  • 23

    5. Transesterificati

    on of ethylene

    carbonate.

    Low yield Zirconium &

    titanium

    compound.

    Produced large

    amount of

    byproducts

    6. Esterification of

    Oxalic acid and

    Reduction with

    H2

    Yield : 70%

    Selectivity: 90%

    Copper

    catalyst

    High conversion but

    catalyst removal is

    very difficult.

    7. Direct one stage

    synthesis of

    Ethylene glycol

    from syn gas

    Selectivity: 65%

    Temp:

    190-230oC

    Pressure:

    3400atm

    Rhodium

    catalyst

    (Homogeneous

    catalyst route.)

    As crude prices

    increase this process

    will become more

    economical.

    Use of very high

    pressure

    Not prove to be

    indirect route may

    be viable or not.

    Catalyst is very

    sensitive and

    expensive.

    8. Hydrolysis of

    glycol diacetate.

    Yield : 90%

    Selectivity: 95%

    Temp: 160oC

    Pressure:

    2.4MPa

    Pd complexes

    pdcl2+NaNO3

    Very low conversion

    H2O+C2H4O Ko HOCH2CH2OH ---------------- (1)

    C2H4O + HOCH2CH2OH Ki HO (CH2CH2O)2 H ---------------- (2)

    Where k0,and k1 are the rate constants.

  • 24

    Now all ethylene and propylene glycols is produced in industry by a non catalyzed

    reaction. Product distribution in reaction (1) is regulated by the oxide/water ratio in

    the initial reaction mixture. The distribution factor b = k1/k0 for a non catalyzed

    reaction of ethylene oxide with water is in the range of 1.92.8. For this reason large

    excess of water (up to 20 molar equiv.) is applied to increase the monoglycol yield on

    the industrial scale. This results in a considerable power cost at the final product

    isolation stage from dilute aqueous solutions. i.e. energy consumption for the

    distillation of large amount of excess water is high. Also the selectivity of ethylene

    oxide hydrolysis is low i.e. 10% is converted to Diethylene glycol and tri ethylene

    glycol.

    One of the ways of increasing the monoglycol selectivity and, therefore, of decreasing

    water excess is the application of catalysts accelerating only the first step of the

    reaction (1). There are much research has been carried out to improve this process.

    The search for better catalyst is an objective for increase the selectivity and decrease

    the excess water. As evident from the kinetic data the distribution factor b = k1/k0 is

    reduced -0.10.2 at the concentration of some salts of about 0.5 mol/l. This enables to

    produce monoethyleneglycol with high selectivity at waterethyleneoxide molar ratio

    close to 10.

    5.2.2 Catalyst:

    A cross-linked styrenedivinylbenzene anion exchange resin (SBR) in the HCO3/

    CO3-

    form, activated by anion exchanging with sodium bicarbonate solution used as

    catalysts. (Dow Chemical produced anion-exchange resins: DOWEX SBR). The

    ethylene oxide hydration process in a catalytic fixed-bed tube reactor was studied .The

    properties of initial resins are summarized below:

    Functional group : - [PhN (CH3)3] +

    Total exchange capacity (equiv./l) : 1.4

    Particle size (mm) : 0.3-1.2

    5.3 PROCESS DESCRIPTION:

    This process produced mono ethylene glycol by the catalytic hydrolysis of ethylene

    oxide in the presence of less excess of water. After the hydrolysis reaction is

    completed the glycol is separated from the excess water and then refined to produce

    mono ethylene glycol (MEG). The process is devided in to five different sections.

  • 25

    5.3.1 MEG reaction unit:

    Ethylene oxides mixed with recycle water and pumped to glycol reactor where it is

    reacted with water at 1050C &1.5 MPa in the presence of catalyst. The Reactor is

    Catalytic Plug flow Fixed bed type. The reaction volume consists of two phase, the

    liquid phase and ionite (catalyst) phase. The liquid streams through catalyst bed in a

    plug flow regime. The catalytic and non catalytic ethylene oxide hydration takes place

    in the ionite phase, and only non catalytic reaction takes place in the liquid phase. The

    distribution of the components of the reaction mixture between liquid and ionite

    phases is result of the rapid equilibrium. The glycol reactor operate at approximately

    1.5MPa.pressure which is supplied by the reactor feed pump. The reactor effluent

    goes to the evaporation unit for the evaporation of excess water.

    5.3.2 MEG evaporation unit:

    The glycol evaporation system consists of multiple effect evaporation system(three

    effects). The reactor effluent flows by difference in pressure from one evaporator to

    the next the water content of glycol is reduced to about 15% in the evaporators. The

    remaining water is removed in drying column, the pressure of the system is such that

    the reactor effluent is maintained as a liquid and is fed as such in to the vapor portion

    of the first effect evaporator.

    Evaporation in the first effect is accomplished by 12Kg/cm2 (g) pressure steam. The

    overhead vapor from the first effect is used as heating media in the second effect. The

    steam condensate from the first effect is goes to the medium pressure condensate

    header.

    The overhead vapor from the second effect is used as heating media in the third effect.

    The third effect operated under vacuum. The vacuum is maintained by using steam jet

    ejector. The bottom of the third effect containing 15% water is fed to crude glycol

    tank via glycol pump, which is then fed to the drying unit. The condensate from first

    two effects and the vapor from third effect containing water and some amount of

    glycol are fed to the glycol recovery unit.

    5.3.3 MEG drying unit:

    The concentrated glycol from the third effect is containing approximately 15% water.

    Essentially all the water is removed from the aqueous ethylene glycol solution in the

    drying column. Normally the drying column is fed from the crude glycol tank. The

    drying column operated under vacuum which is maintained by steam jet ejector.

    Drying column bottom which are free from water are transferred by column bottom

  • 26

    pump to MEG refining column. Where the MEG is separated from the higher glycol,

    Water vapors leaving the top of the drying column are fed to MEG recovery unit for

    glycol recovery. (An inert gas line is provided at the base of the drying column for

    breaking the vacuum).

    5.3.4 MEG refining unit:

    Drying column bottoms essentially free of water are fed to the MEG refining column.

    (PACKED COLUMN). About 15% of the feed to the MEG column enters as vapor

    due to flashing. MEG product is withdrawn from the top of the column. Some MEG is

    purged in the overhead to the vacuum jets to reduce the aldehydes in the product. The

    MEG column bottoms primarily di-ethylene glycols are pumped from the column

    bottom to the storage tank. The MEG column operates at a pressure of 10mmHg (A).

    The vacuum is maintained by MEG column ejector system. The MEG column

    condenser is mounted directly on the top of the MEG column.

    5.3.5 MEG recovery unit:

    The MEG leaving along with water from the Top of the multiple effect evaporator &

    drying column are recovered in the MEG Recovery Column (PLATE COLUMN).

    The column is operated under Atmospheric pressure.MEG leaving from the bottom of

    the column and the water leaving from the top of the column are Recycle to reactor.

  • 27

    CHAPTER VI

    MATERIAL BALANCE

    Material balances are the basis of process design. A material balance taken over

    complete process will determine the quantities of raw materials required and products

    produced. Balances over Individual process until set the process stream flows and

    compositions. The general conservation equation for any process can be written as

    Material out = material in + accumulation

    For a steady state process the accumulation term is zero. If a chemical reaction is

    taking place a particular chemical species may be formed or consumed. But if there is

    no chemical reaction, the steady state balance reduces to:

    Material out = Material in

    A balance equation can be written for each separately identifiable species present,

    elements, compounds and for total material. [10]

    6.1 BASIS:

    Basis: 100000TPA

    The process is planned and developed as a continuous process. A plant is operated for

    24 Hours per day and 333 per year.

    No of working days = 333days

    Capacity = 333

    1000000

    = 300.3 T/days

    = 201.47 Kmol/hr.

    6.2 MOLECULAR WEIGHT (KG / KMOL):

    Ethylene Glycol : 62

    Water : 18

    Carbon Dioxide [CO2] : 44.01

    Water [H2O] : 18

    Nitrogen [N2] : 28

  • 28

    6.3 MATERIAL BALANCE OF INDIVIDUAL EQUIPMENT:

    This is the amount of MEG obtained from the distillation column,

    So assuming that 99% of MEG in the feed to the Distillation column (Refining

    Column) is obtained in the distillate & also 93% of MEG in feed to the Recovery

    Column is recovered from Recovery Column.

    Kmol of MEG in feed to the distillation column

    = 204.70 Kmol/hr.

    6.3.1 Reactor:

    In the reactor following reaction take place

    C2H4O + H2O HOCH2CH2OH --------- (1)

    (Ethylene oxide) (Water) (Mono Ethylene Glycol)

    C2H4O + HOCH2CH2OH HOCH2CH2OH --------- (2)

    (Ethylene oxide) (Mono Ethylene Glycol) (Higher Glycol)

    As selectivity = 98%

    Moles of undesired product formed =98

    70.204

    = 2.088 Kmol

    Moles of MEG to be produced from reactor = 206.788kmol

    Moles of ethylene oxide reacted by reaction I

    = 206.788 Kmol.

    Moles of ethylene oxide reacted by reaction I I

    Ethylene Oxide = 9190.54 Kg

    = 208.876 Kmols

    Water = 37597.68 Kg

    = 2088.76 Kmol

    Mono Ethylene Glycol = 204.7Kmols

    = 12691.4 Kg

    Water = 1881.972 Kmols

    = 33875.496Kg

    Higher glycol = 2.088 Kmol

    = 221.328Kg

    REACTOR

    Temp. = 100 0C

    Conversion = 100 %

    Pressure = 1.5-2MPa

  • 29

    = 2.088 Kmol.

    Total Moles of ethylene oxide reacted = 206.788 + 2.088

    = 208.876 Kmol.

    As conversion = 100%

    [6]

    Moles of ethylene oxide charged = 208.876kmol

    From the literature we know that the ratio of WATER TO ETHYLENE OXIDE =10

    Amount of water fed to reactor = 2088.76 Kmol. (Including excess)

    From the reaction moles of water reacted = 206.788 Kmol.

    M.B.ON WATER:

    Moles of water fed = Moles of water reacted + Moles of water unreacted

    2088.76 = 206.788 + Moles of water unreacted

    Moles of water unreacted = 1881.972kmol

    M.B.ON MEG:

    Moles of MEG in the product = 206.788 2.088

    = 204.7 Kmol

    Table 6.1 Material balance over reactor

    Component In, Kg Out, kg

    Ethylene oxide 9190.54 -

    Water 37597.68 33875.496

    Mono Ethylene Glycol - 12691.4

    Higher Glycol - 221.328

    6.3.2 Triple Effect Evaporator:

    Consider the water content of glycol is reduced to 15% i.e. 85% of water is to be

    removed.

    Consider triple effect evaporator as single unit.

    Amount of water removed = 0.851881.972

    = 1599.6762 Kmol.

    = 28794.1715 Kg

    Total quantity of water at the top = 1599.6762 Kmol.

  • 30

    = 28794.1716 kg.

    Remaining 15% water are still in the bottom along with the MEG and Higher glycol.

    Amount of water in the bottom = 1881.972-1599.6762

    = 282.2958 Kmol.

    = 5081.324 Kg

    There is some quantity of glycol carry over along with water from the top of

    evaporator.

    Amount of glycol carry over along with water from 1st

    effect = 165.58 kg

    Amount of glycol carry over along with water from IIst effect = 189.139kg

    1st effect evaporator

    Pressure = 7 kg/cm2

    Temp = 159 oC

    F = 2088.76 Kmol = (46788.224 kg)

    M.E.G = 204.7Kmol

    = 12691.4 Kg

    Water =1881.972 Kmol

    = 33875.496Kg

    H.G = 2.088 Kmol

    = 221.328Kg

    W1= 8285.66kg

    MEG = 165.58kg

    H2O = 8120.08kg

    2nd

    effect evaporator

    Pressure = 3.5 kg/cm2

    Temp = 141 oC

    W2= 9689.31kg

    MEG = 189.139kg

    H2O = 9500.171kg

    To MEG Recovery column

    Y= 1610.8012kmol

    To 3rd

    effect evaporator

    To 2nd

    effect evaporator

    From 2nd

    effect

    evaporator

  • 31

    Amount of glycol carry over along with water from IIst effect = 335.064 kg

    (Finding using VLE calculation)

    Total amount of glycol carry over along with water = 689.783 Kgm.

    =11.125 Kmol

    Total quantity (water +MEG) leaving from the top of effect = 1599.6762+11.125

    Y = 1610.8012 Kmol.

    TAKING OVERALL M.B

    F = Y + X

    2088.76 = 1610.8012 + X

    X = 477.9588 Kmol.

    (Total quantity leaving from the bottom of last effect)

    Table 6.2 Material balance over Triple effect evaporator

    Component In, Kg Out, Kg

    Liquid phase Vapor phase

    Water 33875.496 5081.355 28794.141

    MEG 12691.4 12001.617 689.783

    HG 221.328 221.328 -

    3rd

    effect evaporator

    Pressure = 0.25 kg/cm2

    Temp = 118 oC

    To MEG Recovery column

    Y= 1610.8012kmol

    From 3rd

    effect

    evaporator

    To MEG Refining

    column

    X = 477.9588 Kmol

    W3= 11508.96kg

    MEG = 335.064kg

    H2O = 11173.89kg

  • 32

    6.3.3 Drying Column:

    Consider all the water are removed in the drying column

    Amount of water removed = 5018.324 Kgm

    = 282.295 Kmol.

    There is some quantity of glycol carry over along with water from the top of drying

    column

    Amount of glycol carry over along with water from drying column = 456.061kg

    =7.3558 Kmol.

    (Finding using VLE calculation)

    Total quantity leaving from top of drying column

    = (Amount of water +Amount of MEG)

    = 282.295 +7.3558

    = 289.65 Kmol.

    TAKING OVERALL M.B

    F = Y + X

    477.9588 = 289.65 + X

    X = 188.306 Kmol.

    (Total quantity leaving from the bottom of drying column)

    Now ,

    Total amount of MEG leaving along with water during evaporation of water

    F = 477.9588 kmol = 17304.2585 kg

    MEG = 12001.606kg

    H2O = 5081.324 kg.

    HG = 221.328kg.

    Y= 289.295 Kmol = 5537.385 kg

    MEG = 456.061kg

    H2O = 5081.324 kg

    .

    X = 188.306 Kmol = 11766.873 kg

    MEG = 186.218kmol

    = 115453545kg

    HG = 2.088 Kmol

    = 221.328kg

    .

    Drying column

    Pressure = 0.21 kg/cm2

    Temp = 87 oC

  • 33

    = (Amount of MEG leaving from top of

    TEE + Amount of MEG leaving from

    top of drying column)

    = 689.783+456.061

    = 1145.844 Kgm.

    = 18.4813 Kmol.

    Amount of feed to MEG Recovery column

    = (Amount of MEG leaving along with

    water during evaporation + Amount of

    water removed)

    = 18.4813+1881.973

    = 1900.451 Kmol.

    Table 6.3 Material balance over drying column

    Component In, Kg Out, Kg

    Liquid phase Vapor phase

    Water 5081.324 - 5081.324

    MEG 12001.606 11545.3545 456.061

    HG 221.328 221.328 -

    6.3.4 MEG Refining Column (Packed Column):

    F = 188.306 Kmol = 11766.873 kg

    MEG = 186.218kmol

    =11545.545kg

    HG =2.088kmol

    = 221.328kg

    D= 184.54 Kmol = 11448.8616 kg

    MEG = 184.355kmol

    (0.999.high purity)

    HG = 0.18454kmol

    W = 3.766 Kmol = 317.664 kg

    MEG = 1.8523kmol

    HG = 1.9136kmol

    MEG refining column

    Pressure = 10 mmHg

    Temp = 93.2 oC

  • 34

    Assuming 99% recovery, of total MEG feed to distillation column, is obtained in the

    distillate.

    Kmol of MEG in Distillate = 188.306 0.99 x 0.98891

    = 184.355 Kmol / hr.

    = 11431.0818 Kg/hr.

    Kmol of Distillate ( D ) = 184.355 / 0.999

    = 184.54 Kmol / hr.

    Avg. M.W. of distillate = (0.999 x 62) + (0.001 x 106)

    = 62.044 kg / Kmol.

    Amt. of Distillate (D) = 184.54 x 62.04

    = 11448.8618 kg / hr.

    Amt. of HG in Distillate = 184.54 x 0.001

    = 0.18454 Kmol / hr.

    = 0.18454 x 106

    = 19.561 kg / hr.

    Kmol of feed (F) = 188.306 Kmol / hr.

    = 11766.873 kg/hr

    TAKING OVER ALL M.B.

    F = D + W

    188.306 = 184.54 + W

    W = 3.766 Kmol /hr.

    M.B. ON MEG

    F x (Xf MEG) = D x (Xd MEG) + W x (Xb MEG)

    188.306 x 0.9889 = 184.54 x 0.999 + 3.766 x Xb MEG

    Xb MEG = 0.4918 (mol.fr.of MEG in Bottoms)

    XbHG = (1- 0.4918)

    = 0.5081 (mol.fr.of HG in Bottoms)

    Kmol of MEG in Bottoms = 0.4918 x 3.766

    = 1.8521 Kmol / hr

    Mol. Weight of MEG = 62 kg/Kmol

    = 114.831 kg/hr.

    Kmol of HG in Bottoms = 0.5081 x 3.766

    = 1.9135 Kmol / hr.

  • 35

    Mol. Weight of HG =106 kg/Kmol

    = 1.9135 x 106

    = 202.83 kg/hr.

    Table 6.4 Material balance over Refining packed column

    Component In, Kg Out, Kg

    Liquid phase Vapor phase

    MEG 11545.545 114.8426 11430.01

    HG 221.328 202.8416 19.56124

    6.3.5 MEG recovery column (Plate column):

    Assuming 99.9 % of total water in feed to distillation column is obtained in the

    distillate.

    Kmol of Water in Distillate = 1881.97 x 0.999

    = 1880.08 Kmol / hr

    Kmol of Distillate ( D ) = 1880.08 / 0.999

    = 1881.97 Kmol / hr.

    Avg. M.W. of distillate = (0.999 x 18) + (0.001 x 62)

    = 18.044 kg / Kmol.

    Amt. of Distillate (D) = 1881.97 x 18.044

    F = 1900.451kmol = 35021.339 kg

    MEG = 18.481kmol

    =1145.844kg

    H2O =1881.97kmol

    = 33875.496kg.

    D= 1881.97kmol = 11766.873 kg

    MEG =1.88kmol

    H2O =1880.08kmol

    W = 18.481kmol =1205.55 kg

    MEG = 17.122kmol

    H2O = 1.3584kmol

    MEG recovery column

    Plate column

  • 36

    = 33958.266 kg /hr

    Amt. of MEG in Distillate = 1881.97 x 0.001

    = 1.88 Kmol / hr

    = 1.88 x 62

    = 116.56 kg/ hr.

    Amount of feed ( F ) = 1900.451 Kmol/hr

    = 35021.339 kg/hr.

    TAKING OVERALL M.B.

    F = D+ W

    1900.451 = 1881.47 + W

    W = 18.481kmol / hr

    M.B. ON WATER

    F x (Xf H) = D x (Xd H) + W x (Xb H)

    1900.451 x 0.99 = 1881.97 x 0.999 + 18.481 x Xb W

    Xb W = 0.0735 (mol.fr.of Water in Bottoms)

    Xb MEG = 1- 0.0735

    = 0.9264 (mol.fr.of MEG in Bottoms)

    Amount of MEG in Bottoms = 18.481 x 0.9264

    = 17.122 Kmol / hr

    = 17.122 x 62

    = 1061.56 kg/hr.

    Kmol of Water in Bottoms = 18.481 17.130

    = 1.3584 Kmol / hr

    = 1.3584 x 18

    = 143.99 kg/ hr.

    Table 6.5 Material balance over Recovery plate column

    Component In, Kg Out, Kg

    Liquid phase Vapor phase

    Water 33875.496 24.4512 33841.44

    MEG 1145.844 1061.546 116.56

  • 37

    Table 6.6 Overall material balances

    Equipment Component In, kg Out, Kg

    Liquid phase Vapor phase

    Reactor Ethylene oxide 9190.54 - -

    Water 37597.68 33875.496 -

    MEG - 12691.4 -

    HG - 221.328 -

    Triple effect

    evaporator

    Water 33875.496 5081.355 28794.141

    MEG 12691.4 12001.617 689.783

    HG 221.328 221.328 -

    Drying column Water 5081.324 5081.324

    MEG 12001.606 11545.3545 456.061

    HG 221.328 221.328 -

    MEG refining

    column

    MEG 11545.545 114.8426 11430.01

    HG 221.328 202.8416 19.56124

    MEG recovery

    column

    Water 33875.496 24.4512 33841.44

    MEG 1145.844 1061.546 116.56

  • 38

    CHAPTER VII

    ENERGY BALANCE

    The first law of thermodynamics demands that energy be neither created nor

    destroyed. The following is a systematic energy balance performed for each unit of

    the process. The datum temperature for calculation is taken as 0C.

    The different properties like specific heat, heat of reaction, heat of vaporization, etc.

    are taken to be constant over the temperature range.

    7.1 REACTOR: [9,11]

    In the reactor following reaction take place

    C2H4O + H2O HOCH2CH2OH ------------- (1)

    (Ethylene oxide) (Water) (Mono Ethylene Glycol)

    C2H4O + HOCH2CH2OH HOCH2CH2OH ------------ (2)

    (Ethylene oxide) (Mono Ethylene Glycol) (Higher Glycol)

    Table 7.1 Heat capacity and Enthalpy data

    COMPONENT )(298

    0

    kmolkj

    H f

    )(kkmol

    kjC p

    IN

    Ethylene oxide -77704 99.106

    Water -285830 75.673

    OUT

    MonoEthyleneGlyocol -454800 75.673

    Di-EthyleneGlyocol -285831 189.39

    Water -562570 441.602

    Assume reference temp. = 250C

    7.1.1 Enthalpy of formation of reaction

    For first reaction

    Rffpf HHH000

    REACTOR

    Temp. = 100 0C

    Conversion = 100 %

    Pressure = 1.5-2MPa

    Ethylene Oxide = 9190.54 Kg

    = 208.876 Kmols

    Water = 37597.68 Kg

    = 2088.76 Kmol

    Mono Ethylene Glycol = 204.7Kmols

    = 12691.4 Kg

    Water = 1881.972 Kmols

    = 33875.496Kg

    Higher glycol = 2.088 Kmol

    = 221.328Kg

  • 39

    = [-454800] - [-(77704) + (-285830)]

    = -91266 KJ/ Kmol of EO Reacted

    = -91266 x 206.788

    = -18.872 x 106 KJ / hr

    For second reaction

    Rffpf HHH000

    = [-562570] [(-77704) + (-454800)]

    = -30066 KJ/ Kmol of EO Reacted

    = -30066 x 2.088

    = -62.77x103 KJ / hr

    Total enthalpy of formation = (-18.872 x 106

    ) + (-62.77x103

    )

    = -18.9347 x 106

    KJ / hr

    Enthalpy of reactants

    As reactants are added at 250C, so, its Enthalpy becomes 0.

    Enthalpy of products

    THGmCpCmCmHWATERpMEGpp

    )(

    = [ ( 204.7 x 189.39) + ( 1881.972 x 75.673 ) + (2.088 x 441.60) ] ( 105 25 )

    = 14.5683 x 106 KJ / hr

    Enthalpy of reaction

    RfpR HHHH 00

    = (14.5683 x 106) + (-18.9347 x 10

    6) - 0

    = - 4.3043 x 106 KJ / hr

    So, it indicates that it is an exothermic reaction.

    So, to control temp. Inside the reactor, cooling water is passed on shell side to remove

    the heat.

    Assuming cooling water entered at 25 o C and leave at 45

    o C

    Q = m x Cp x T

    - 4.3043 x 106 = m x 75.79627 x 20

    m = 2.8394 x 10

    3 Kg / hr (cooling rate) [9,11]

  • 40

    7.2 TRIPPLE EFFECT EVAPORATOR:

    Water to be evaporated = 28794.716Kg/hr

    Total feed wF = 46788.224 Kg/hr

    The balances applying to this problem are:

    First effect: wSS + wF (tF t1) Cp = w11

    Second effect: w11 + (wF w1) ( t1 t2) Cp = w22

    Third effect: w22 + (wF w1-w2) (t2 t3) Cp = w33

    1st effect evaporator

    Pressure = 7 kg/cm2

    Temp = 159 oC

    3rd

    effect evaporator

    Pressure = 0.25 kg/cm2

    Temp = 118 oC

    W1= 8285.66kg

    MEG = 165.58kg

    H2O = 8120.08kg

    F = 2088.76 Kmol = (46788.224 kg)

    M.E.G = 204.7Kmol

    = 12691.4 Kg

    Water =1881.972 Kmol

    = 33875.496Kg

    H.G = 2.088 Kmol

    = 221.328Kg

    To 2nd

    effect evaporator

    2nd

    effect evaporator

    Pressure = 3.5 kg/cm2

    Temp = 141 oC

    W2= 9689.31kg

    MEG = 189.139kg

    H2O = 9500.171kg

    To MEG Recovery column

    Y= 1610.8012kmol

    To 3rd

    effect

    evaporator

    From 2nd

    effect

    evaporator

    From 3rd

    effect

    evaporator

    W3= 11508.96kg

    MEG = 335.064kg

    H2O = 11173.89kg

    To MEG Refining

    column

    X = 477.9588 Kmol

    To MEG Recovery column

    Y= 1610.8012kmol

  • 41

    Material balances: w1 + w2 + w3 = w1-3

    tF = 1050C

    Consider steam is entered at 12 kg/cm2 so Ts = 190.825

    0C

    (After finding boiling point of solution)

    Also last effect operates at a vacuum of 0.25 Kg/cm2

    So t3 = 106.15oC (steam temp at 0.25 kg/cm

    2)

    Consider for forward feed multiple effect evaporator pressure differences between

    effects will be nearly equal.

    So average pressure difference = 385.056 KPa /effect

    Table-7.2 Breaking up the total pressure difference:

    Pressur

    e, KPa

    Steam or

    vapor

    temp. C

    , KJ/Kg

    (Steam)

    , KJ/Kg

    (MEG)

    Steam chest, 1st

    effect

    1179.69 TS= 190.82 S = 2210.8

    Steam chest,

    2nd

    effect

    794.63 t1=175.17 1 = 2244.1 1 = 982.935

    Steam chest,

    3rd

    effect

    409.57 t2=152.585 2 = 2284.0 2 = 1001.15

    Vapor to

    condenser

    24.53 t3= 106.155 3 = 2379.1 3 =1022.317

    7.2.1 First effect:

    Cp avg. = xiCpi

    = 4.196 KJ/Kg o K

    avg = 2016.38 KJ/Kg

    WSS + wF (tF t1) Cp = w11

    (WS x 1973.62) + (46788.224 x - 70.17 x 4.196) = w1 x 2016.38

    w1 = 0.9787WS 6830.42 ----------------------------- (1)

    7.2.2 Second effect:

    Cp avg. = xiCpi

    = 4.105 KJ/Kg o K

    avg = 2088.28 KJ/Kg

  • 42

    w11 + (wF w1) (t1 t2) Cp = w22

    w1 X 2016.38 + (46788.224 -w1) (175.17-152.585) x 4.05 = w2 2088.28

    Put value of w1 from equation (1) and finally

    w2 = 0.9022WS 4245.22 ---------------------------- (2)

    7.2.3 Third effect:

    Cp avg. = xiCpi

    = 3.873 KJ/Kg o K

    avg = 2207.35 KJ/Kg

    w22 + (wF w1-w2) ( t2 t3) Cp = w33

    w22088.28 + (46788.224 w1 w2) (152.585 106.155)3.873 = w3 2207.35

    Put value of W2 from equation 2 and finally we get

    w3 = 0.70WS 697.42 ----------------------------------- (3)

    Taking overall Material balances:

    w1 + w2 + w3 = w1-3

    0.9787WS 6830.42 +0.9022WS 4245.22 + 0.70WS 697.42 = 28794.1716 +

    689.783

    WS = 15.445 x 103 Kg/hr ( steam rate is required.)

    From above equations we calculated,

    w1 = 8285.66 Kg/hr

    w2 = 9689.31 Kg/hr

    w3 = 11508.96 Kg/hr

    Now , Enthalpy out from the bottom of the last effect,

    Tbottom = 122oC Trefrence = 25

    oC

    T = 97oC.

    Enthalpy out from Bottom = (mCpT )MEG + ( mCpT )WATER + ( mCpT )HG

    = [(12001.606 x 3.077) + (5081.324 x 4.378) + (221.328 x 4.1032)] x 97

    = 5.828 x 106 KJ / hr

  • 43

    7.3 DRYING COLUMN:

    Toperating = 87 oC Trefrence = 25

    oC

    Hence T = 62oC.

    Poperating = 0.25 kg /cm2

    Enthalpy in = 2.802 x 10

    6 kJ / hr

    7.3.1 Enthalpy out from Top

    = ( m )water + ( m )MEG +( mCpT )

    = [(5081.324 x 2366.1) + (456.061 x 1109 .75)] + [289.65 x 75.2 x 64]

    = 12.529 x 106 kJ / hr

    7.3.2 Enthalpy out from Bottom

    = (mCpT )MEG + ( mCpT )HG

    = [(186.218 x 187.90) + (432.72 x 2.088)] x 62

    = 2.225 x 106 kJ / hr

    Total Enthalpy out = Enthalpy out from (Top + Bottom)

    = 12.529 x106 + 2.225 x 10

    6

    = 14.75 x106 kJ / hr

    Q = Total Enthalpy out - Enthalpy of feed

    Drying column

    Pressure = 0.21 kg/cm2

    Temp = 87 oC

    Y= 289.295 Kmol = 5537.385 kg

    MEG = 456.061kg

    H2O = 5081.324 kg

    .

    X = 188.306 Kmol = 11766.873 kg

    MEG = 186.218kmol

    = 115453545kg

    HG = 2.088 Kmol

    = 221.328kg

    .

    F = 477.9588 kmol = 17304.2585 kg

    MEG = 12001.606kg

    H2O = 5081.324 kg.

    HG = 221.328kg.

  • 44

    Enthalpy of feed = 5.828 x 106 kJ / hr

    Q = 14.75 x106

    +5.828 x 106

    = 8.926 x 106 kJ / hr

    Amount of steam required,

    Consider the steam enter at 2 kg/cm2 & 118.719oC

    Steam = 2205.82 kJ / kg

    Q = m steam

    8.926 x 106 =

    m x 2205.82

    m = 4046.6 kg / hr (Rate of steam)

    7.4 MEG REFINING COLUMN:

    7.4.1 for top:

    Ttop = 91.8 oC Trefrence = 25

    oC

    T = 66.8 oC

    Poperating = 10 mmHg

    Cpmean of MEG = 189.70 kJ / kmol oK

    Cpmean of DEA = 441.6 kJ / kmol oK

    MEG refining column

    Pressure = 10 mmHg

    Temp = 93.2 oC

    W = 3.766 Kmol = 317.664 kg

    MEG = 1.8523kmol

    HG = 1.9136kmol

    F = 188.306 Kmol = 11766.873 kg

    MEG = 186.218kmol

    =11545.545kg

    HG =2.088kmol

    = 221.328kg

    D= 184.54 Kmol = 11448.8616 kg

    MEG = 184.355kmol

    (0.999.high purity)

    HG = 0.18454kmol

  • 45

    Total Enthalpy out with Distillate = (mCpT ) MEG + (mCpT )DEG

    = [(184.355 x 189.70) + (0.18454 x 441.6)] x 66.8

    QD = 2.341 x 106 kJ / hr

    Reflux Ratio = 0.71 (finding using Mc Cabe & Thiel Method)

    i.e. L/D = 0.71

    L = 0.71D

    Vapor formed at the top V = L + D

    = 0.71D + D

    = 0.71 x 184.355

    V = 315.247 kmol / hr

    Reflux L = 0.71D

    = 0.71 x 184.355

    L = 130.89 kmol / hr

    Enthalpy out with vapor:

    QV = latent heat + sensible heat associated with that vapor

    = m + (mCpT)

    MEG = 68.578 x 103 kJ / kmol

    DEG = 72.067 x 103 kJ / kmol

    AVEG = 68.58 x 103 kJ / kmol

    QV = [(315.247 x 68.58 x 103) + (315.247 x 188.298 x 66.8)]

    = 25.58 x 106 kJ / hr

    Enthalpy out with Reflux:

    QReflux = ( mCpT )Reflux

    = [ 130.89 x 188.551 x 66.8 ]

    = 1.6485 x106 kJ / hr

  • 46

    Condenser load, QC :

    = QV ( QReflux + QD )

    = [(25.58 x 106

    ) (1.6485 x106 + 2.341 x 106 )]

    = 21.595 x 106 kJ / hr

    Assuming cooling water enters the condenser at 25oC & leave at 45

    oC

    QC = (mCpT )cooling water

    21.595 x 106

    = m x 75.7962 x 20

    m = 11.63 x 103 kg / hr (Rate of cooling water)

    7.4.2 For bottom:

    Tbottom = 94.6 oC T = 69.6 oC

    Cpmean of MEG = 188.531 kJ / kmol 0K

    Cpmean of DEG = 443.2 kJ / kmol 0K

    Enthalpy out with Residue, QResidue = ( mCpT )liq

    = [(1.8528 x 188.531) MEG + (1.9136 x 443.2) DEG] x 69.6

    = 83.34 x 106 kJ / hr

    Reboiler Load:

    Reboiler heat load is determined from a balance over complete system

    QB + QFeed = QD + QW + QC

    QFeed = 2.252 x 106 kJ / hr

    QB = (21.595 x 106

    + 83.34 x 106 - 2.252 x 10

    6 + 2.341 x 10

    6 )

    = 21.794 x 106

    kJ / hr

    Amount of steam required,

    Consider the steam enter at 2 kg/cm2 & 118.719oC

    steam = 2205.82 kJ / kg

    QB = m steam

  • 47

    21.794 x 106

    = m x 2205.82

    m = 9.88 x 10 3 kg / hr ( Rate of steam )

    7.5 MEG RECOVERY COLUMN:

    7.5.1 For top:

    Ttop = 194oC Trefrence = 25

    oC

    T = 169 oC

    Poperating = 760 mmHg

    Cpmean of MEG = 197.24 kJ / kmol oK

    Cpmean of H2O = 76.55 kJ / kmol oK

    Total Enthalpy out with Distillate = (mCpT )MEG + (mCpT ) WATER

    = [(1881.08 x 76.55) + (1.874 x 197.24)] x 169

    QD = 24.40 x 106 kJ / hr

    Reflux Ratio = 0.51 (finding using Mc Cabe & Thiel Method)

    i.e. L/D = 0.51

    L = 0.51D

    Vapor formed at the top V = L + D

    = 0.51D + D

    MEG recovery column

    Plate column

    D= 184.54 Kmol = 11448.8616 kg

    MEG = 184.355kmol

    (0.999.high purity)

    HG = 0.18454kmol

    W = 3.766 Kmol = 317.664 kg

    MEG = 1.8523kmol

    HG = 1.9136kmol

    F = 188.306 Kmol = 11766.873 kg

    MEG = 186.218kmol

    =11545.545kg

    HG =2.088kmol

    = 221.328kg

  • 48

    = 0.51 x 1881.97

    V = 2841.77kmol / hr

    Reflux L = 0.71D

    = 0.51 x 1881.97

    L = 959.80 kmol / hr

    Enthalpy out with vapor:

    QV = latent heat + sensible heat associated with that vapor

    = m + (mCpT)

    MEG = 1023.184 kJ / Kg H2O = 2231.8 kJ / Kg

    AVEG = 40.195 x 103 kJ / kmol

    QV = [(2841.77 x 40.195 x 103) + (2841.77 x 197.24x 169)]

    = 208.95 106

    kJ / hr

    Enthalpy out with Reflux:

    QReflux = (mCpT) Reflux

    = [959.80 x 76.67 x 169]

    = 12.43 x106 kJ / hr

    Condenser load

    QC = QV ( QReflux + QD )

    = [(208.95 106

    ) (12.43 x106 + 24.40 x 106 )]

    = 172.12 x 106

    kJ / hr

    Assuming cooling water enter the condenser at 25oC & leaves at 45

    oC

    QC = (mCpT )cooling water

    172.12 x 106

    = m x 75.7962 x 20

    m = 113.63 x 103 kg / hr (Rate of cooling water)

  • 49

    7.5.2 For bottom:

    Tbottom = 198 oC Trefrence = 25

    oC

    T = 173 oC

    Cpmean of MEG = 197.6285 kJ / kmol 0K

    Cpmean of H2O = 76.607 kJ / kmol 0K

    Enthalpy out with Residue:

    QResidue = ( mCpT )liq

    = [(17.122 x 197.6285) MEG + (1.3584 x 76.607 )DEG ] x 173

    = 603.39 x 103 kJ / hr

    Reboiler Load:

    Reboiler heat load is determined from a balance over complete system

    QB + QFeed = QD + QW + QC

    QFeed = ( mCpT )feed

    = [(18.481 x 187.97) MEG + (1881.97x 74.51) WATER] x 80

    = 143.71x 103 kJ / hr

    Reboiler load

    QB = [( 603.39 x 103 + 172.12 x 10

    6 + 24.40 x 10

    6 ) (143.71x 103) ]

    = 196.97 x 106

    kJ / hr

    Amount of steam required,

    Consider the steam enter at 2 kg/cm2 & 118.719oC

    steam =2037.51 kJ / kg

    QB = m steam

    196.97 x 106

    = m x 2037.51

    m = 97.67 x 10 3 kg / hr ( Rate of steam ) [9,11]

  • 50

    CHAPTER VIII

    REACTIONS KINETICS & THERMODYNAMICS

    8.1 REACTOR KINETICS:

    Here,

    FAO = 208.876 Kmol/hr

    = 9190.544 Kg/hr

    V0 = 10.649 m3/hr

    FAO = CAO V0

    208.87 = Cao x 10.649

    CAO = 19.6136 Kmol/m3 = 19.6136 mol/lit

    Similarly,

    CBO = 5.555 Kmol/m3 = 55.555 mol/lit

    Now, Rate of reaction is given by

    d (C2H4O) = {K0([H2O] + b [Gyi]) + Kct [HCO3]} X

    dt {{[H2O] + p [Gyi]}x [Oxide]}

    Where,

    Gyi = concentration of reactant (mol/lit)

    [H2O] = concentration of water (mol/lit)

    [Oxide] = concentration of oxide (mol/lit)

    b = distribution factor =2.8

    p = 1.88

    REACTOR

    Temp. = 50 0C

    Conversion = 100

    %

    E. O = 9190.54 Kg

    = 208.876 Kmols

    Water = 37597.68 Kg

    = 2088.76 Kmol

    Product =2088.76 kmol

    = (46788.224 kg)

    M.E.G = 204.7Kmol

    = 12691.4 Kg

    Water =1881.972 Kmol

    = 33875.496Kg

    H.G = 2.088 Kmol

    = 221.328Kg

  • 51

    d (C2H4O) = rA = {K0(CB + b (CA + CB)) + Kct [HCO3] } X

    dt {(CB + p (CA + CB)) x [CA]}

    Rate constant Ko is given by,

    K0 = exp [9.077 9355]

    T

    where T = temperature o K

    K0 = exp [9.077 9355]

    378

    K0 = 1.5627 x 10-7

    L2 = 0.0005625 L

    2

    mol2. Sec mol

    2. hr

    Similarly catalyst Rate constant Kct is given by,

    Kct = exp [18.24 10574]

    T

    Kct = 5.926 x 10-5

    L2 = 0.21334 L

    2

    mol2. Sec mol

    2. hr

    Now,

    CAO XA = CBO XB

    a b

    19.6136 XA = 55.555 XB

    1 1

    XB = 0.3530 XA

    - rA ={ K0[(CBO(1 0.3530 XA)) + 2.8 (CAO (1 XA) + CBO (1 0.3530 XA))]

    + Kct [0.25]} x {[CBO (1 0.3530 XA) + 1.88 [CAO (1 XA) + CBO (1

    0.3530 XA)]}x CAO (1 XA)}

    - rA ={ 0.0005625 [55.555 (1 0.3530 XA)) + 2.8 (19.6136 (1 XA) +

    55.555 (1 0.3530 XA)] + 0.05533} x {55.555 (1 0.3530 XA) +

    1.88 [19.6135 (1 XA) + 55.555 (1 0.3530 XA)]}x

    19.6136 (1 XA)}

  • 52

    Table-8.1 Different value of XA and finding corresponding rate (-rA),

    XA = 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.98

    -rA = 654.5 532.40 424.57 330.131 248.286 178.2369 119.1836 70.31 30.86 53.60

    (1/-

    rA)

    (lit.hr

    /mol)

    0.005 0.0018 0.0023 0.00302 0.00402 0.00561 0.0084 0.01 0.03 0.186

    From the above data plotting a XA Vs )1

    (rA

    & finding the area under he curve at

    Xa = 0.98

    Fig-4 Reactor volume Chart

    AREA UNDER THE CURVE = 0.01227

    Plug flow equation related to volume is given by [15]

    XA

    V = d XA

    FAO 0 - rA

    XA

    d XA =Area under the curve

    0 - rA

    Area under the curve = 0.01227

  • 53

    FAo

    V = 0.01227

    V = 2562.90 lit

    V = 2.56 m3

    Now we have

    = Empty volume in bed

    Total bed Volume

    1 = 1 Empty volume in bed

    Total bed Volume

    1 = Total Bed Vol Empty volume in bed

    Total bed Volume

    But Total Bed Empty volume in Bed = Volume of Catalyst.

    1 = Volume of Catalyst

    Total bed Volume

    1 = Volume of Catalyst

    2.56 m3

    Consider = 0.6

    Total Volume of Catalyst = 1.024 m3

    8.2 THERMODYNAMICS

    As we know the Gibbs free energy is given by following equation

    G = -RT lnK

    Where K = Kequ = (ka * kb)/ (kc * kd)

    From reaction,

    ka and kb are rate constants for the products.

    Similarly kc and kd are rate constants for the reactants. But assuming reaction is

    exothermic and irreversible; the values of kc and kd will not be in consideration to

    finding out equilibrium rate constant.

    Hence, Kequ is given by

    Kequ = ka kb

    Enthalpy, Gibbs free energy and specific heat data are below at reaction temperature

    100 0C in the form of functional group. [11]

  • 54

    -O- group: Cp = 19.28 KJ /.Kg K, G = -15.38 KJ / Kg K

    H = -1467.62 KJ /.Kg K

    -CH2- group: Cp = 20.43 KJ /.Kg K, G = -3.87 KJ / Kg K

    H = -1516.94 KJ /Kg K

    -OH- group: Cp = -1.83 KJ /.Kg K, G = -36.785 KJ / Kg K

    H = 96.75 KJ /.Kg K

    H2O: G = -8.728 KJ / Kg K

    G total = G product - G reactant

    C2H4O + H2O HOCH2CH2OH --------- (1)

    (Ethylene oxide) (Water) (Mono Ethylene Glycol)

    G = [(-81.31)]-[(-23.12) + (-8.728)]

    G = - 49.53 KJ/Kmol K

    Ka = exp [-(-49.53) / (8314*373)]

    Ka =1.00

    ln(K2/K1)= E/R[(1/T1)-(1/T2)] [15]

    ln(9.5/8)= E/8.314[(1/368)-(1/373)]

    T2 reaction at 100 oC= 373K

    T1 reaction at 95 oC=368K

    0.26236 = 6.2382* E *10-6

    E = 7.52*E*-7 J/mol

  • 55

    CHAPTER IX

    MAJOR EQUIPMENT DESIGN

    9.1 DESIGN OF REACTOR AS A SHELL & TUBE HEAT EXCHANGER :

    Consider the reactants are flow on tube side and cooling water are on shell side

    Catalysts are fill inside the tube.

    9.1.1 Process Design: [22]

    Consider length of tube = 4m

    Diameter of tube = 2.5 cm

    Volume of one tube = (d)2 (L) 4

    = (2.5 x 10-2)2 (4) 4

    = 1.9634 x 10-3

    m3

    Table-9.1 Properties at arithmetic mean temperature.

    Props. Shell Side

    (Water) (30oC

    )

    Tube side

    (Ethylene oxide + H2O) (65oC)

    Cp 5.1865 (KJ/Kg oK) 4.840 (KJ/Kg

    oK)

    9 x 10-4

    (Kg/m.Sec) 4.187 x 10-4

    (Kg/m.Sec)

    K 0.62 (w/m.oK) 0.54 (w/m.

    oK)

    995.40 (Kg/m3) 973.09 (Kg/m

    3)

    No. of tube = Volume of reactor

    Volume of one tube

    = 001963.0

    56.2

    No. of tubes = 1304 Nos.

    Area of tube per pass:

    Atp = (d) 2

    (Ntp)

    4

    = (2.5 x 10-2)2 (1304) 4

    Atp = 0.64 m2

    Velocity:

    U = Atp

    m

  • 56

    m = 12.996 Kg/Sec

    U = 64.009.973

    996.12

    x

    U = 0.02 m/sec

    Now, NRe = )1(

    x

    du

    = (2.5 x 10-2

    ) x (0.02) x (973.09)

    (4.187 x 10-4

    ) x (1 -0.6)

    NRe = 2905.09

    Now, AO = Nt x x d xL

    = (1304) x x (2.5 x 10-2) x (4) AO = 409.66 m

    2

    Shell diameter:

    Ds =

    5.02

    )(637.0

    L

    xdoPAox

    Ctp

    CLR

    Consider the Triangular pitch

    CTP = 0.9

    CL = 0.7

    Take PR = Pube pitch ratio

    = 1.25

    Ds = 0.637 0.7 409.66 x (1.25)2 x (2.5 x 10

    -2)

    0.5

    0.9 4

    Ds = 1.123 m

    Now, No. of tubes that can be accommodate

    Nt = 0.875 CTP __(Ds)2

    CL (PR)2 (d)

    2

    = 0.875 0.9 ____(1.123)2

    0.7 (1.25)2 (0.025)

    2

    = 1452.8 > Total No of tube that is required.

    Shell side H.T.C :

    k

    hoxDe)( =

    14.0333.055.0

    36.0

    w

    bxk

    Cpxx

    DexGsx

    For triangular pitch

  • 57

    De = 4 3 PT2 d2

    2 4

    d

    Pitch ratio = PR = d

    PT

    1.5= 0025.0

    TP

    PT = 0.03125 m

    De = 4 3 (0.31252 x (2.5 x 10-2)2

    2 4

    x 0.0025

    De = 0.018 m

    Gs = As

    m

    As = TP

    DsxCxB

    C = PT do = 0.03125 0.025 = 0.00625

    B = 0.4 Ds

    = 0.4 x 1.125

    = 0.45

    As = 1.123 x 0.00625 x 0.45 0.03125

    As = 0.101 m2

    Gs = As

    m

    = 12.996

    0.10

    Gs = 128.58 Kg/m2.sec

    From the above equation,

  • 58

    62.0

    )018.0(hox = 14.0

    333.04355.0

    41

    62.0

    109101865.5

    109

    58.128018.036.0 x

    xxxx

    x

    xx

    ho = 1825.04km

    w20

    Tube side H.T.C:

    Nu = 0.023 (NRe)0.