Evaluation of Crude Oil, Petroleum Products and Petrochemicals | Chemical Technology - Chemical Engineering PDF Download

Major Parameters of Gasoline Specifications

Major parameters for gasoline included in Bharat or Euro norms are

• Lead phase out
• Lower RVP
• Lower benzene & aromatics
• Lower olefin content
• Limited Oxygen content
• Lower Sulfur content

Other parameters of importance are RON, MON, Lead, gum, oxidation stability, density, VLI index, FBP. In case of reformulated gasoline aromatics, olefins oxygen, Antiknock index, vapor lock index

Major Parameters of Diesel Specifications

Major parameters for diesel included in Bharat or Euro norms are

• Low sulfur
• Low aromatics
• High cetane number
• Lower density
• Lower distillation end point Other parameters for diesel are density, viscosity, cetane number distillation range, sulphur, carbon residues, oxidation stability, Flash point, acid value, ash and water contents  

Evaluation of Feed Stocks for Petrochemicals (Olefin, Aromatics, and Linear Alkyl Benzen (Lab) Plants) 

Olefin , aromatic and LAB production are three major Petrochemical building blocks.  Various feed stocks olefins, aromatics and surfactants are given in Table M-VI 2.2.

Input cost of feed constituents is a major portion of the variable cost of production in petrochemical plants. Major feed input olefin, aromatics and surfactants are  Ethane propane from natural gas, naphtha, kerosene from the refinery and LPG from refinery, pyrolysis gasoline  from steam crackers, Benzene from aromatic plant. Feed quality monitoring and improvement efforts are therefore very important aspects having significant impact on the economics of the operation cost. The precursors and undesirable constituents in feed including catalyst and adsorbents poisons should be known, analyzed and monitored continuously.  

 Table M-VI 2.2: Feed stocks for Olefin, Aromatics ans LAB  

• Naphthenes: Naphthene yield olefins of higher carbon number. Butane yield increases appreciable with naphthenic feed. Naphthenes also enhance production of aromatics.
• Aromatics: The aromatics is feed are highly refractory and they pass through the furnace unreacted.
• Sulphur: The sulphur in feed suppress stream reforming reaction catalyzed by nickel present in radiant coil. Optimum level of sulphur is 1 ppm.
• Physical Properties: Density, distillation range are useful and give a rough assessment of feed quality.
• Ethylene: The following components in feed give ethylene in decreasing order:  
  • Ethane, Butane to Decane, 3 and 2 Methyl hexane, 2 methyl Pentane/ 2,2 Dimethyl Butane, Isopentane
• Propylene: The following components in feed give propylene in decreasing order:
  • Isobutane, n-nutane, n-propane, 3 methyl pentane, 2,3 dimethyl butane, 2 methyl hexane, n-pentane, 3 methyl hexane, iso pentane.
• Butadiene: The following components of feed give butadiene is decreasing order:
  • Cyclo hexane, methyl cyclo pentane. 

• C₈ Paraffin's: Dehydro cyclisation of C₈ paraffin's yield aromatics difficult to 20% C₈ paraffins gets converted to C₈ aromatics.
• C₈ Aromatics: Pass as refractory and directly contribute to C₈ aromatic production.
• C₈ Aromatic Precursors: It is useful to monitor aromatic precursors= 0.2* C₈ P + 0.9 * C₈ N + 1.0 C₈ A  

Surfactants:  

Linear alkyl benzene is one of important feed stock for production of surfactant whose demands is increasing with increasing population all over the world. LAB requires paraffins for production of olefins of carbon range C10-12 to have more biodegradable detergent.  Benzene is required for alkylation of olefin to produce LAB. Feed stock for praffins are Kerosene feed 150-265 oC cut from refinery containing mainly nC₇ to NC₁₈ components which is fractionated to remove lighter and heavier fractions. The fractionated cut is hydrotreated for removal of sulphur and nitrogen catalyst which are poisonous to molex adsorbent molecular sieve.

Desirable:

 LAB requires olefin and benzene. At present trend is for manufacture of biodegradable low molecular weight LAB, Paraffins containing  nC₁₀ to nC₁₃ carbon atoms are required in LAB  manufacture which is obtained by fractionation of kerosene. Nc12 improve the flammability of LAB product.

Some of the undesirable components in the feed which are sensitive to molex molecular sieves are contaminants like water, sulphur, nitrogen, oxygen, chlorides, metallic poisons.Kkey properties of LAB feed stocks are density, ASTM distillation, IBP,FBP, sulphur, bromine index  ,aromatics, saybolt colour, smoke point, flash point, nitrogen component analysis for n-C10 to nC13, total normal paraffins.