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Petroleum refineries

Chemical, refinery and petrochemical industries are complex large establishments that by nature of their operations are subject to a number of high risk factors, among them the maintenance of the mechanical integrity of process and storage equipment.

 Production volume, geographical distribution of the industry in Europe, the world.  The majority of EU and OECD countries are host to at least one petroleum refinery, if not several, and those countries without refineries all have petroleum storage depots who share some of the same storage and handling issues as refineries.  OECD countries represent an estimated 49.2% [4]  of global refining capacity, and all together EU countries (including non-OECD members) represent an approximate 18% of global refining capacity .






Processes differ from refinery to refinery but processes commonly present in refineries include:

-The atmospheric crude distillation unit - Distills the incoming crude oil into various fractions for further processing in other unit

-The catalytic reformer unit - a chemical process used to convert petroleum refinery naphthas, typically having low octane ratings, into high-octane liquid products called reformates which are components of high-octane gasoline 

-Hydrotreatment unit(desulphurisation) - a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products, especially fuels.

-The fluid catalytic cracking unit -used to convert the high-boiling, high-molecular weight hydrocarbon fractions of petroleum crude oils to more valuable gasoline, olefinic gases, and other products

commonly involved in accidents

Crude oil
Hydrocarbons of various compositions
Sulphur and sulphide compounds
Chlorine and chloride compounds
Hydrogen sulphide
Hydrogen chloride
Hydrogen flouride

 -The hydrocracking process - the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds

- Isomerisation - To convert low-octane n-paraffins to high-octane iso-paraffins

-Delayed coker unit - heats a residual oil feed to its thermal cracking temperature in order to break the heavy, long chain hydrocarbon molecules of the residual oil into coker gas oil and petroleum coke

-The alkylation unit - an acid catalyzed conversion of C3-C5 olefins with isobutane into highly branched C5-C12 isoparaffins collectively called alkylate, a valuable gasoline blending component.  Alkylation reactions are catalyzed by liquid and solid acids, including H2SO4, AlCl3-HCl, HF, HF-BF3, H2SO4-HSO3F (Fluorosulfuric acid), Trifluoromethane sulfonic acid chlorided Pt alumina, BF3 on alumina, zeolites, and ion exchange resins.

-Gas treating processes - the process used to remove the so acid gases, espcially hydrogen sulfide and carbon dioxide from the refinery gas streams.

-Storage and transfer - Every refinery has an internal network, sometimes kilometres long, of pipelines for transferring product and inputs between units.  It also has tank storage areas to store product.  External pipelines may also connect to various internal tanks and pipelines to manage the inflow and outflow of process inputs and products.

Substances released in refinery accidents involving corrosion by number of accidents. An accident may have involved the release of more than one substance and therefore,  the total number of accidents counted in the figure above exceeds the total number of  accidents studied. (Wood et al. 2013. Corrosion-Related Accidents in Petroleum Refineries: Lessons Learned from Accidents in EU and OECD Countries)