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0601 2506-01

A New Technical Solution for Glycol Ether Production:

Brake Fluid fromSugar Cane

DANIELE MALOSSAURS HALLER

SULZER CHEMTECH

Sulzer Chemtech has a good name as a supplier of key components for column internals in thechemical industry. A new plant for the productionof ethylene glycol ether in Kashipur (India), which went on stream in July 2001, also showsthat the engineers from Oberwinterthur are up to the mark when it comes to providingtechnology for complete plants with reaction and distillation sections.

1 The first plant with a continuous process in India hasbeen producing glycol ether for the manufacture of brake fluid since summer 2001. It produces 10 000 tons per annum.The largest plant engineered by Sulzer is designed for a production of 40 000 tons ethylene glycol ether per year.

Quite often, it is not only themarket requirement that

determines the decision for themanufacture of a specific chemicalproduct. The available raw materi-als or logistic standpoints play themore important role from time totime, which was also the case bythe above-mentioned glycol etherplant (see Box and Fig. 1).

FIELD OF APPLICATION AND MARKET

Ethylene glycol ether is producedthrough the conversion of alcohols(methanol, ethanol and n-butanol)with ethylene oxide. Behind trade

names such as Cellosolve®, Car-bitole® and Dowanole®, we findvarious glycol ethers that areemployed in diverse fields, e.g. assolvents in the varnish and lacquersector, emulsifiers for mineral andvegetable oils or for the forming ofball-point pen paste and printinginks.One of the main fields of applica-tion for glycol ether, however, is itsuse in brake fluid (Fig. 2). Numer-ous producers of glycol ether there-fore build a production facility forthe manufacture of brake fluids inthe immediate vicinity of the gly-col ether plant and can thus oper-

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Ethylene oxide Ethanol Ethylene glycol

CH2–CH2 + CH3–CH2–OH CH3–CH2–O–CH2–CH2–OH

O

3 Ethanol, butanol or methanol can be used for the reaction with ethyleneoxide. A number of distillation stages separate the resultant mixture intomono-, di- and higher glycol ethers which, as constituents of solvent andcleaning agents or as processing aids, are suitable for the manufacturer ofvarnishes and lacquers. Shown here is the reaction formula by the use ofethanol.

2 The brake fluid in hydraulic brakes (with glycol ether as the mainconstituent) transfers the brake effort from the brake cylinder to thebrake block in a uniform manner. The fluid must have a high boilingpoint and is not allowed to attack the brake-line materials or the seals.

ate the two installations flexiblyand according to market require-ments – like India Glycols Limitedwith its plant in Kashipur.The worldwide consumption ofethylene glycol ether is about750 000 t/a, the largest manufac-turers are found in Europe, theU.S.A. and Japan. The worldwidegrowth is determined at present by the brake fluid requirement,whereby the biggest growth ratesare expected in the countries ofAsia and South America.

CUSTOMER-SPECIFICDEVELOPMENT

Distillation plants all over theworld have been equipped withcolumn internals from Sulzer forsome 40 years. In co-operationwith experienced partners andinterested customers, the know-how acquired thereby is also uti-lized for the development of tech-nology for complete plants withreaction and distillation sections.On the basis of a contract study,Sulzer Chemtech developed a con-tinuous process for the productionof ethylene glycol ether. The part-ners are the Polish instituteCiezkiej Syntezy Organicznej “Bla-chownia” (ICSO), where the neces-sary customer tests were made,

and the Italian company ConserS.p.A., which was responsible forthe design of the reactor. In a laterstep, a customer was found withIndia Glycols Limited who wasconvinced of the new technology.

DESCRIPTION OF THE PROCESS

The various glycol ether types arecreated with a catalytic reaction ofethylene oxide with the alcohols –methanol, ethanol or butanol(Fig. 3 ). This reaction is exother-mic; the reactor therefore has to becooled constantly. The continuousprocess as offered by SulzerChemtech (Fig. 4 ) facilitates ex-tremely good utilization of the rawmaterials. Since the reaction isoperated with a surplus of alcohol,an atmospheric distillation sepa-

rates the unused alcohol from theglycol ether, so that it can be usedagain. The quantity of alcohol fedto the reactor also influences thedistribution of the end product.However, the reaction of glycolether with alcohol cannot be con-trolled in such a manner that onlyone single type of glycol ether isformed. Consequently, the glycolether mixture is separated off in athree-stage vacuum distillation.The lower-boiling mono-glycolether is distilled under vacuum inthe first column. The pressure iseven lower in the second vacuumcolumn, where the di-glycol etheris taken off. The less volatile tri-glycol ether is separated from thestill higher boiling polyglycolethers in the third vacuum col-umn.

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ADVANTAGES OF THE SULZER PROCESS

The production experience gainedfrom the very similar ethanol-amine plants (see STR 2/2000,p. 32) was incorporated in the eth-ylene glycol ether technology. TheSulzer reaction takes place at rela-tively low temperatures and pres-sures, which minimizes the forma-tion of by-products. The design ofthe reactor ensures great flexibili-ty in the distribution of the prod-ucts. A further advantage of theSulzer process is the possibility ofproducing ethylene glycol etherfrom various alcohols in the same

plant, for which a suitable catalystis required.The catalyst employed by Sulzer ischaracterized by the followingadvantages:• Homogenous• No incrustation in the down-

stream evaporators of the distil-lation columns

• Hardly any water has to beremoved

• Non-corrosiveFor the equipment of the distilla-tion units, Sulzer Chemtech drawsupon its wide and long experiencein the field of vacuum distillationtechnology:

• The columns are equipped withMellapak structured packing(Fig. 5). The excellent efficiencyof the separation reduces theconsumption of energy and per-mits a lower overall height of thecolumn.

• Thanks to its special design, thecondensers only cause very low-pressure loss during the vacuumdistillation.

• The use of falling-film evapora-tors facilitates low temperatureswhich, in turn, prevents lossesand possible deterioration in thequality of the end product.

FROM SUGAR CANE TO BRAKE FLUIDThere is an important cultivated area for sugar cane in the vicinity ofKashipur, about 200 km east of Delhi in India. The molasses, a wasteproduct that results from the refinement of sugar, serves as a raw mate-rial for the manufacture of different spirits. The world’s only commercial-ized production plant of ethylene oxide from molasses is operated by IndiaGlycols Limited. The paths for the further processing of the products fromthe molasses (alcohol and ethylene oxide) lead to ethylene glycol ethers,which are the main constituents of brake fluid for hydraulic brakes.The normal route to ethylene oxide is via commercially available ethyl-ene. Ethylene, the petrochemical substance with the largest productionvolume worldwide, is obtained primarily through the thermal crackingof higher hydrocarbons. The catalytic oxidation of ethylene produces eth-ylene oxide, a cyclic ether, which has been manufactured chemically sincethe beginning of the 20th century. Ethylene oxide is an important inter-mediate product for the manufacture of solvents, plastic and surfactants,as well as a raw material for the chemical production of ethylene glycol,glycol ethers or ethanolamine. Since ethylene oxide is an extremely reac-tive and explosive gas at room temperature, it is very difficult to trans-port, and so it is obvious that plants for the further processing are builtnearby.The distillation of fermented molasses at the plant of India Glycols inKashipur leads to ethanol which is reacted with ethylene oxide resultingin ethylene glycol ether. Brake fluid is a mixture of ethylene glycol ethers,polypropylene glycol and additives for the lubrication. With the continu-ous process at the plant in India, the ratio of the various ethylene glycolethers can be adjusted in such a way that brake fluid can be manufac-tured in a quality that fulfils the requirements of the local market.

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SCOPE OF DELIVERY FROMSULZER CHEMTECH

Sulzer Chemtech provides thebasic engineering for continuouslyoperating glycol ether plants, aswell as the license for the produc-tion of ethylene glycol ether and forthe manufacture of brake fluids.Furthermore, the detail planningand delivery of the key compo-nents that are essential for theproper functioning of the plant arewithin the scope of supply of Sulz-er Chemtech. These are: the reac-tor, packing in the distillationcolumns, heat exchangers, vacuumsystem, and the control system.With the aforementioned scope ofdelivery, Sulzer Chemtech canguarantee that the plant will oper-ate reliably and as planned. More-over, that it will fulfil the require-ments for important values, suchas the product purity and capacityof the plant.Sulzer Chemtech does not onlyoffer tailor-made technology forthe production of ethylene glycolether alone. Technology is alsoavailable for ethanolamine. For

example, a Sulzer plant has beenproducing ethanolamine from eth-ylene oxide and ammonia in north-eastern China since 1997. Ethanol-amine is employed for gas-washingpurposes and as a starting mate-rial for the synthesis of fine chemi-cals. Ω

F O R M O R E D E T A I L SSulzer ChemtechUrs HallerPostfach 65CH-8404 WinterthurSwitzerlandTelephone +41 (0)52-262 37 98 Fax +41 (0)52-262 00 76E-mail urs.haller@sulzer.com

5 Since the metal packing from Sulzer Chemtech(photo: MellapakPlus) cause only extremely lowpressure losses, the distillation can take place atlow temperatures. This increases the purity andquality of the separated glycol ethers.

4 The manufacture of glycol ether is conducted in three main stages: mixing and reaction,alcohol recovery as well as the separation of the end products in a three-stage distillation.The key components developed by Sulzer Chemtech are employed in all three stages.

Mono-glycol ether

Di-glycol ether

Tri-glycol ether

Tri-glycol ether and higher polymers

Ethylene oxide

Catalyst

Alcohol

Mixing and reaction Alcohol recovery Distillative separation

Alcohol