PPT Unit-8 Notes

8/3/2019 PPT Unit-8 Notes

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UNIT – 8

CHEMICALS FROM ETHANE-ETHYLENE-ACETYLENE

1. Occurrence of Ethane:

Ethane is associated with Methane as a second major component (upto 10%) in natural

gas. In casing head gas and associated gas its presence is high upto 20%. Ethane is

associated with other gases to a nominal extent of 5 – 15 % in secondary processes like

thermal cracking or reforming and catalytic reforming.

Physical Properties:

• Molecular formula : C2H6

• Molar mass : 30.07 g/mol

• Appearance : colourless gas

• Density : 1.282 kg/m3(15 C gas, 1 atm)

546.49 kg/m3(liquid, at b.p.,1 atm)

• Melting point : −183.01 °C (90.14 K)

• Boiling point : −89 °C (184 K)

• Solubility in water : very low

2. Oxidation of Ethane:

While Methane oxidation primarily yields methanol and small percentage of

formaldehyde, Ethane oxidation gives a complex mixture of products. Though the

composition of products vary depending upon the conditions of oxidation, still the

components are same. When ethane is oxidized at a pressure of 100 bars, the following

products are expected:

Product Temperature at 2620C

Time 40 minTemperature at 278

0C

Time 5 min

Ethyl alcohol

Methyl alcohol

Acetaldehyde

Acetic acid

Formaldehyde

24.3 %

15.5%

6.3%

52.3%

1.6%

28.2%

43.6%

20%

5.5%

2.7%

Ethane, Propane and higher alkanes can be oxidized by air instead of oxygen. It is

preferred to introduce steam along with air when oxidation of higher paraffins undertaken

to moderate the reaction.

3. Production of Ethylene:

Feed stock is preheated and sent into pyrolysis unit where steam and feed reacts to form

pyrolysed compounds. The temperature maintaining in the pyrolyser (furnace) is around

9000C. The products from the furnace are passed through a high pressure (HP) generator



and sent into a fractionator where quenching can take place. Only heavy oils are

separated from lights in the quencher. The volatiles from the quencher are cooled and

compressed to 5 – 6 MPa, and sent into a separator where part of heavy hydrocarbons are

liquefied and separated, and goes into the Debutaniser to separate C4 components. The

vapors from the separator are infested with acidic constituents like CO, CO2, H2S, SO2

are separated with caustic wash in the scrubber and the products are dried with activated

alumina. Hydrogen is separated in vapor phase from the product gases and sent into

hydrogen purification unit and removed separately. Then the product gases are liquefiedand sent into Demethaniser unit to separate C1 components and the products are sent into

Deethaniser unit to separate C2 and C3 components. The products from Deethaniser are

sent into hydrogenation unit where acetylene converted to Ethylene. Then the products

from the hydrogenation unit sent into C2 splitter to separate Ethylene and unconverted

ethane. Unconverted ethane is recycled back to the process.

Process Folw Sheet:



4. VINYL CHLORIDE MONOMER (VCM):

FLOW SHEET:



PROCESS DESCRIPTION:

5. PRODUCTION OF VINYLACETATE MONOMER (VAM): The chemistry involving the acetylene based process is shown below. Zinc acetate deposited on charcoal acts as catalyst and the reaction proceeds at 170 0C – 200 0C.





6. PRODUCTION OF ETHANOL FROM ETHYLENE:



PROCESS DESCRIPTION:

FLOW SHEET:



7. ACETALDEHYDE FROM ACETYLENE:

8. PRODUCTION OF ACETYLENE:



A. CALCIUM CARBIDE:

Note: I will send last topic.

PPT Unit-8 Notes

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