Introduction: Status of Petroleum Refinery, Crude Oil And Natural Gas Origin (Part - 2) | Chemical Technology - Chemical Engineering PDF Download

Refinery Processes  

Refining of crude oils or petroleum essentially consists of primary separation processes and secondary conversion processes. The petroleum refining process is the separation of the different hydrocarbons present in the crude oil into useful fractions and the conversion of some of the hydrocarbons into products having higher quality performance. Atmospheric and vacuum distillation of crude oils is the main primary separation processes producing various straight run products, e.g., gasoline to lube oils/vacuum gas oils (VGO). These products, particularly the light and middle distillates, i.e., gasoline, kerosene and diesel are more in demand than their direct availability from crude oils, all over the world. The typical refinery operation involves separation processes, conversion processes, finishing processes, environmental protection processes. Typical refinery process diagram is shown in Figure M-VI 1.2

Separation Processes

• Distillation
• Absorption
• Extraction
• Crystallisation
• Adsorption

Primary Distilation (Atmospheric Distillation)

• Refinery gases
• Liquefied petroleum gases  
• Gasolines or naphtha (light/heavy)
• Kerosene, lamp oil jet fuel
• Diesel oil and domestic heating oils
• Heavy Industrial fuels

Secondary Disllation (Vacuum Distillation)

• Light Distillate
• Middle distillate
• Heavy distillate
• Asphalt/bitumen

Conversion Processes 

Process for Improvement of Properties 

• Catalytic reforming
• Isomerisation
• Alkylation 

Figure M-VI 1.2: Typical Refinery Processes and Products

• Visbreaking
• Coking

Catalytic Processes

• Catalytic cracking(FCC)
• Hydrocracking
• Steam reforming
• Hydroconversion

Finishing Processes 

• Hydrotreatment/hydrogenation
• Sweetening

Environmental Protection Processes 

• Acid gas processing
• Stack gas processing
• Waste water treatment process

Types of Petroleum Refining Processes 

Primary Processes: Separating crude into its various fractions e.g. CDU/VDU

Secondary Processes: Processing residues from primary processes and upgrading them to distillates e.g. FCCU, HCU

Residue Upgradation Processes: Bottom of the barrel upgradation eg. RFCCU, DCU, DCC 

Finishing/ Product Quality Improvement Processes:Processes to improve product quality and meet stringent product quality specifications eg. DHDS, DHDT, CRU

Refining Capacity 

Global oil consumption and refining capacity, World Refining Capacity Country wise 2009 are given in Table M-VI 1.5 and Figure M-VI 1.3. Present refining capacity in India is million tones per annum. The present import of crude in India is around 180 million tones per annum. It is expected that the import of crude oil has to exceed 240 million tones per annum in the next five years, if GDP growth of around 6 to 7percent were to be sustained.

Table M-VI 1.5: Global Oil Consumption and Refining Capacity 2009  million barrel/d    

Figure M-VI 1.3: World Refining Capacity Country wise 2009

Total: 90.7 mbpd (4533 MMTPA) 

Changing Scenario in Gasoline and Diesel Specifications 

Major Parameters of Gasoline Specifications [Table M-VI 1.6]

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

Major Parameters of Diesel Specifications [Table M-VI 1.7] 

• Low sulfur
• Low aromatics
• High cetane number
• Lower density
• Lower distillation end point

Table M-VI 1.6: Key Specification of Gasoline  

Table M-VI 1.7: Key Specification of High Speed Diesel (HSD)