The refinary industry is continuously faced with changes. These changes are in the quality of the crudes processed, the product slate and the required qualities of the products. To cope up with these changes refineries must introduce new technologies from time to time or improve already practised technologies by revamping process units, by applying different often improved catalysts or both.
In very general sense, petroleum refining can be tracked back over 5000 years to the times when asphalt materials and oils were isolated from areas where natural seepage occurred. Petroleum refining is the separation of petroleum into fractions and the subsequent treating of these fractions to yield marketable products. Refinery process must be selected and products manufactured to give a balanced operation in which petroleum is converted into a variety of products in amounts that are in accord with the demand for each.
Petroleum refineries and petrochemical plants by the nature of their business have to process, store and handle large quantities of flammable chemicals. Operations involving these chemicals are accident-prone and a number of fire and explosions have occurred at various places in the world in the last century with a substantial loss of life and property.
As a result of increasing awareness amongest the public and the growing regulatory pressures in the last two decades, safety of the plant now receives a higher degree of management attention that in the past.
The elements of process safety management broadly consists of the following elements:
a) Identification of hazards and their accident potentials.
b) Assessment of risk
c) Identification of control measures
d) Implementation of control measures
e) Audit, review and improvement actions.
An electrostatic desalting unit of petroleum refining process is shown below:
By the hazard identification the pathways whereby the material can lead to a hazard event. Thus in the context of petroleum refineries and petrochemical plants, the objective of hazard identification exercise would be to identify possible sources of significant leakage, their causes and also how such leakage can be result into a major fire or an explosion.
Methods to identify hazards are:
1) Review of past incidents
2) Use of checklists
3) Safety audit
4) Hazard and operability study (HAZOP)
5) Failure mode and effect analysis (FMEA)
6) Fault tree analysis
Process safety management techniques to prevent major damage in petroleum refineries and petrochemical plants due to fire and explosion incidents have been discussed. The techniques cover hazard identification risk assessment and implementation of measures for reduction of risk to levels as low as reasonably practicable.
Risk reduction measured include design of safe plants, quality control during constructions a good standard of maintenance and also implementation of safe systems and procedures in operation.
However good a plant have been designed and built a high quality of productivity and a high standard of safety cannot be achieved unless the management ensures that formal systems and procedures are in place.
The following are some of the important areas that deserve attention:
a) Safety policy
b) Operating procedures
c) Accident investigations
d) Recruitment and training of personnel
e) Emergency preparedness
f) Safety audit
Petroleum Refining Technology and Economics
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The refining industry has been the subject of the four major forces that affect most industries and which have hastened the development of new petroleum refining processes.
a) The demand for products such as gasoline, diesel, fuel oil and jet fuel.
b) Feedstock supply, specifically the changing quality of crude oil and geopolities between different countries and the emergence of alternate feed supplies such as bitumen from tar sand, natural gas and coal.
c) Environmental regulations that include more stringent regulations in relation to sulfur in gasoline and diesel.
d) Technology development such as new catalysts and processes.
In early days of the twentieth century refining processes were developed to extract kerosene for lamps. Any other products were considered unusable and were usually discarded. Thus first refining processes were developed to purify, stabilize and improve the quality of kerosene.
However, the invention of the internal combustion engine led to a demand for gasoline, for use in increasing quantities as a motor fuel for cars and trucks. This demand on the lower boiling products increased particularly when the market for aviation fuel developed. Thereafter, refining methods has to be constantly adapted and improved to meet the quality requirements and needs of car anf aircraft engines.
To convert crude oil into desired products in an economically feasible and environmentally acceptable manner, refinery process for crude oil are generally divided into three categories:
1) Separation processes of which distillation is the prime example,
2) Conversion processes of which coking and catalytic cracking are prime examples.
3) Finishing processes of which hydrotreating to remove sulfur is a prime example.