UNIVERSITI SAINS MALAYSIASCHOOL OF CHEMICAL ENGINEERING

EKC 111MASS BALANCE

PREPARATION OF ETHYLENE BY CATALYTIC DEHYDRATION OF ETHANOL

NONAMEMATRIC NUMBER

1AIDIL FAIZIE BIN SHADAN 125122

2ANIS SALWANI BT ROZMAN125126

3SARAVANAN REDDY A/L KALIDAS125173

4SITI UMIYAH BINTI OTHMAN123124

5TAN PEI CHIN125181

LECTURERPROF. ABDUL LATIF AHMAD

1) List of side and main reaction in manufacturing of nitric acid:a) Dehydration of ethanol is an endothermic reaction and requires 390 calories per gram of ethylene formed. There are two competitive parallel reactions occurred during the dehydration of ethanol process: C2H5OH C2H4 + H2O + 44.9 kJ/mol2C2H5OH C2H5OC2H5 + H2O 25.1 kJ/molb) The side reaction which produces diethyl ether is an exothermic reaction and it is favoured at low temperature, mainly between 250 C to 300 C, while ethylene production is favoured at higher temperature, 300 C to 500 C. c) With these operational conditions, acetaldehyde and hydrogen are obtained also by the reaction: CH3CH2OH CH3CHO + H2d) Other by-products formed by minor side reactions at higher temperature include methane, propylene, isobutanol, carbon oxide and carbon dioxide

2) Raw materialRaw materials required for preparation of ethylene by catalytic dehydration is mainly ethanol. Ethanol can be produced by fermentation reaction of carbohydrate. Ethanol can be even produced industrially through direct and indirect hydration of petroleum derived ethylene. Ethanol also can be produced from biomass through fermentation of starch (corn) and sugar(sugarcane).

3) Catalyst used Nano scale H-ZSM-5 zeolite catalyst 99.7% ethylene selectivity Temperature of 240 C 630 h lifespan H-ZSM-5 catalyst powder is related to the formation of poly-aromatic compounds silicoaluminophosphates (SAPO) micro catalytic pulse reactor operating at 3 bar different temperatures (250400 C) hydrocarbon pulse (0.55 l) SAPO-11-4 had the best results with 98.0% ethylene selectivity at 250 C, but with many catalysts such as modified HZSM-5 and MCM-41 achieving over 99.0% selectivity, SAPO catalysts are not competitive enough heteropolyacid catalyst supported on a specific type of silica Temperature range of 140250 C three different heteropolyacid catalysts, namely tungstophosphoricacid (TPA), silicotungsticacid (STA) and molybdophosphoricacid (MPA) can be substituted with copper Very high ethylene

4) Properties of Ethanol monohydric primary alcohol melts at - 117.3C and boils at 78.5C miscible (i.e., mixes without separation) with water completely free of water is called absolute ethanol forms a constant-boiling mixture, or azeotrope, with water contains 95% ethanol and 5% water and that boils at 78.15C burns in air with a blue flame, forming carbon dioxide and water It reacts with active metals to form the metal ethoxide and hydrogen reacts with certain acids to form esters, e.g., with acetic acid it forms ethyl acetate can be oxidized to form acetic acid and acetaldehyde can be dehydrated to form diethyl ether or, at higher temperatures, ethylene

5) Unit Operation Used in Both Technology Distillation columnThis is the main equipment where the separation process described above is carried out. In general, the distillation column is separated into3 sections: rectifying (or enriching) section, stripping (or exhausting) section and feed (or flashing) section. At the rectifying section, the more volatile component is removed through contacting the rising vapour with the down-flowing liquid. At the stripping section, the down-flowing liquid is stripped of the more volatile component by the rising vapour.

CondenserThe condenserworks together with the compressor. The compressor pressurizes the refrigerant into a hot liquid. The liquid then flows into the condenserand travels along its many coils.

CompressorsAcompressoris a machine for raising a gas - acompressiblefluid - to a higher level of pressure.

PumpsPumps can be used for returning the reflux liquid back to the distillation column, or for pumping out the bottoms product for storage, or for pumping the feed into the distillation column.

ReboilerThe purpose of the reboiler is to produce the vapour stream in the distillation column, called the reboiled vapour or the boil-up vapour. Reboilers can be both external or internal (stab-in). Steam reboilers or fired reboilers can be used. Fired reboilers typically uses fuel gas or fuel oil or combination of both.

DrumAreflux drumto hold the condensed vapour from the top of the column so that liquid (reflux) can be recycled back to the column

Ethylene-ether feed coolerEthylene-containing stream is fed to the system via line I. This feed is compressed in compressors 2 to a pressure sufficient to maintain the desired pressure of at least 1000 pounds absolute in' the stage of conversion. The recycle ethyl ether stream may be injected via line 3 into the ,compressed ethylene stream. The stream may be' further cooled in cooler 4 to remove the remainder of the heat' 'into converter 5 to aid in keeping the temperature down to the proper level and supply water of reaction. Usually steam is introduced in admixture with the ethylene feed; for example steam and the ethylene feed may be admixed in the proper proportions and fed to compressors 2. Converter 5 is cooled in any suit-- able manner to remove the exothermic heat of reaction.

Ethylene TankEthylene is usually stored as liquid at very low temperatures (around -103C). Cryogenic tanks are commonly employed. Pipelines are frequently used to transfer ethylene. These tanks are made of stainless steel or carbon steel for low temperatures.

DryerUses adsorption techniques to remove moisture and carbon dioxide to less than 1 ppm

Technology 1: Ethylene via Ethanol DehydrationA. Block Flow DiagramB. Process Description

Reaction & Quenching1. Fresh green saturated vapour ethanol (in a heat exchanger).2. The vaporized ethanol is then heated in a furnace.3. Feed stream is sent to the first adiabatic reactor (once contact with the fixed catalyst bed, reaction occurs and temperature drops).4. Tomaintain the appropriate conversion rate and selectivity,the resulting streampasses again through the furnace, reaching the previous inlet temperature and is then sent to the second reactor.5. This is repeated for the third and fourth reactors.6. After leaving the last reactor, the stream is cooled in a heat boiler (low pressure steam is produced).

Compression, Caustic washing & Drying Section1. The water content in the product stream is reduced in a quench column.2. The overhead product stream is submitted to three-stage compression with intercoolers after each stage, followed by a knockout drum (water and aqueous phase hydrocarbons are separated from the compressed vapour and sent to the quench column).3. The vapour stream is then sent to a caustic washing column where a 50% caustic reduces the CO2 concentration to less than 10 ppm.4. The gas stream is then cooled and has all the water removed in the drying systemconsisting of two molecular sieve beds.The dry gas is compressed and heated before being recycled to the regeneration bed.

Purification1. Productstream is cooled by interchange with the product ethylenestream before entering the first purification column.2. Upon leavingthe cooler, the stream is separated into vapour andliquid components3. The stream being fed into twodifferent stages of the ethylene column in order to remove any C3+ residues obtained fromthe dehydration reaction. 4. These residues are removed from the bottom of the column and burned as fuel.5. The overhead product from the ethylene columnundergoes CO removal in a stripper column, (reduces its content in the product stream to 5 ppm).The bottoms of the stripper column, PG ethylene (99.9 wt %), issent to a buffer tank before being vaporized.C. List of Unit Operation Involved in the Process:

D. Detailed Flow Diagram

Technology 2: Green Ethylene via Ethanol DehydrationA. Block Flow Diagram

B. Process Flow DescriptionTreatment sectionFresh ethanol containing about 5 wt% of water is combined with recycled ethanol from the Purification section. The resulting stream is thenflowed into a column for removal of small amounts of aldehydes impurities.The C4 hydrocarbons formed in the reactor are also removed in this column.The resulting overhead stream from the aldehydes removal column is burned as fuel.Reaction sectionThe bottom streamfrom the aldehyde removal column is sent to the feed vaporizer.The vaporized stream is superheated and then flows to the first stage of four adiabatic fixed-bed reactors, containing heteropolyacid catalyst supported by silica.Between each reaction stage, a superheater provides the heat consumed by the endothermic reaction.The stream leaving the reactor is cooled against boiler feed water for low pressure steam generation and sent to the purification area.The generated low pressure steam is used in the aldehyde removal column reboiler.Purification SectionThe reaction outlet stream primarily consists of unreacted ethanol, ethylene and diethyl ether.The stream is sent to a series of columns for ethylene purification.The first column is mainly used to separate the ethylene from the water formed in ethanol dehydration.The ethylene-rich overhead stream is then sent to an ethylene purification column for ethylene and diethyl ether separation.The distillate product from the purification column is polymer grade ethylene.The bottoms are recycled to the aldehyde removal column in the treatment area.The bottoms stream from the ethylene-water separation column is then sent to a dewatering column, in which the water formed in the reaction step is extracted and then sent for treatment outside the plant.The overhead stream from the dewatering column, containing mostly unreacted ethanol and diethyl ether, is also recycled to the aldehyde removal column.C. List of Unit Operation Involved in the Process:

D. Detailed Flow Diagram

CONCLUSIONFirst and foremost, we have a chance to explore more about unit operations involved in a technology as well as achieving a better understanding on chemical plant. As a future chemical engineer, we should know the roles we play in a society. We are able to know the difference between a chemical engineer and a chemist after completing the term paper. In order to play our roles as chemical engineers in industrial production streams, we should have strong basic knowledge on unit operation and chemical plant. So, through this term paper, we learnt that an overall chemical plant is made up of several important basic unit operations through this paper.Besides, we feel glad to have a chance to understand the manufacturing process of ethylene. After completion of the term paper, we gain some knowledge on the whole manufacturing process of ethylene. Our understanding is no longer limited to writing the equations of contact process, but we are able to know that there are several types of production of ethylene by catalytic dehydration of ethanol and each of the plant has their own unit operations as well in their process.All in all, we want to say thank you for giving us a chance to learn as much as we can.

REFERENCE http://base.intratec.us/home/chemical-processes/ethylene/green-ethylene-from-ethanol-via-dehydration-research-economics http://base.intratec.us/home/chemical-processes/ethylene/ethylene-via-ethanol-dehydration http://www.separationprocesses.com/Distillation/DT_Chp04a.htm http://www.engineeringtoolbox.com/pumps-compressors-fans-blowers-d_675.html http://repository.upenn.edu/cgi/viewcontent.cgi?article=1036&context=cbe_sdr