answer the following questions as related to refinery operations, processes and products.
(a). list 4 methods of desulfurization.
(b). state 4 matrices employed in ammonia production considering that catalysts are crucial in chemical processes.
(c).state 3 chemicals applied in ETP(effluent treatment plants) and there uses.
(d). state 5 disadvantages of petroleum coke as a fuel in power plants.
(e). briefly discuss thermal polymerization from a refinery unit.
ANSWER (a)
Methods of desufurization:
1) Hydrodesulfurization (HDS)
It is done by Co feeding oil and H2 to a fixed bed reactor packed with an appropriate HDS catalyst.
2) Extractive desufurization
This method depends on the solubility of organosulfur compound in certain solvents.
3) Ionic Liquid extraction
The extractive desufurization of fuels such as diesel oil by ionic liquids as opposed to traditional organic solvents provides very clean desufurized fuel.
4) Absorptive desufurization.
This method depends upon the ability of solid absorbent to absorb selectively organosulfur compounds from the oil.
ANSWER (b)
Methods of NH3 extraction involving use of catalysts : Catalysts play a role of paramount importance in NH3 extraction as in the following processes.
1) HABER'S PROCESS : Here ammonia is synthesized by reaction between nitrogen from air and hydrogen from natural gas (methane) in 1:3 ratio by volume. The catalyst used in IRON at 400-450 डिग्री Celcius at 200 atmospheric pressure.
2) AMMONIA TREATMENT INSIDE THE REACTOR : This method requires a specific catalyst striping inside the reactor. When a heterogenous catalyst is used effecting oxidation of NH3 to NO3 is carried out, this catalyst will be subjected to stringent temperature conditions inside the reactor and its effectiveness may be reduced due to contamination of certain compounds present in the sludge.
3) DECOMPOSING AMMONIA USING A RUTHENIUM CATALYST : For decomposition of NH3 into hydrogen and nitrogen, ammonia recovered from a coke oven gas combining a catalytic decomposition of ammonia, a basic compound as a required catalyser is added to RUTHENIUM supported on alumina.
4) USE OF Cu/La/Ce COMPOSITE CATALYST: Industrial waste water contains NH3 which is toxic. Use of composite catalysts is very effective in extracting ammonia from industrial waste water.
ANSWER (C)
Chemicals applied in ETP ( Effluent treatment plant) :
1) Aluminium sulphate - - - It is soluble in water and is mainly used as a coagulation agent, which means promoting particle collision by neutralizing charge, in the purification of drinking water and waste water treatment plants.
2) Sodium hydroxide - - - - It raises the pH of water in a variety of applications.
3) Flocculent (dewatering) - - - - Wastewater treatment polymers are synthetic organic Flocculent that are used for clarification, thickening and dewatering applications.
ANSWER (D)
Disadvantage of petrolium coke as a fuel :
1) It is a solid bulk fuel, so involves disadvantage of storage.
2) Significant quantities of fugitive dust from petrolium coke storage and and handling operation present health risk.
3) The particles present in Pet Coke are 10 micrometers or smaller in diameter. They easily pass through the nose and throat and enter the lungs.
4) Once inhaled these particles can affect heart and lungs and can cause serious health problems.
5) The particulate matter present in petrolium coke causes air pollution.
ANSWER(E)
Thermal polymerization : It is a process where heat energy is utilized for effecting polymerization. Here a substance of low molecular weight is transformed into one of the same composition but of higher molecular weight maintaining the atomic arrangement present in the basic molecule.
It is done by successive addition of one molecule to another by means of a functional group such as that present in an aliphatic olefin. Here olefin gases are converted to liquid condensation products,that may be suitable for gasoline or other liquid fuels.
nCH2=CH2 - - - - > H - (CH2CH2)n - H
Here n is usually 2,3 or4.
Polymerization ties two or more olefin together to make polymer gasoline. The double bond in only one olefin is changed to a single bond during each link between two olefins. The product still possess a double bond.
answer the following questions as related to refinery operations, processes and products. (a). list 4 methods...
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