Hydrocracking Units in Petroleum Refineries: What are They?

May 24, 2017

An oil refinery is a little like a chemist's laboratory, except the test tubes and boiling mixes have been enlarged until they straddle massive areas of land. The chemical reactions are also similarly amplified, so the fragile glass beakers are gone. Instead, towering pressure vessels contain the catalysing chemicals. As for hydrocracking units in petroleum refineries, these special catalytic chambers are more active than most refinery units, for there's hydrogen coursing through their innermost workings.

What is Hydrocracking?

A smart engineering student might assume the "hydro" prefix refers to water, but that conjecture is wrong. No, this process uses hydrogen to upgrade "cracked" distillates. In essence, the chambers are formed from several reactor vessels and separators. High temperatures and high pressures break long chained hydrocarbons down in that reactor, so the hostile environment in there requires a robust containment framework. Passed across the hot catalyser, the boiling mixes distill and become unsaturated hydrocarbons. Undoubtedly, these fractions have their place as valuable fuels, but this process is targeting something specific. Enter the hydrogen gas, a simple molecule that further processes the feedstock while controlling the temperature of the various fraction streams. It all sounds complicated, but that chemical complexity pays off in terms of lighter fractions, such as jet fuel and kerosene.

Deconstructing Hydrocracking Mechanisms

Inside the pressurised reactor, the catalysing process is progressing. The hydrocarbon feed and hydrogen are heated, boiled until sulphur and process-contaminating heavy metals are removed. Large molecules are cleaved, lighter fractions break free, and the distillate rises in the distillation tower. Next, the cooling feed flows into a series of separators and fractionators. Pollutants and hydrogen are expelled from the mix, at which point the routed fractions are cooled and condensed. Flash drums and phase separation devices further divide the fractions. There are also numerous supplementary systems in play within the vessels, such as gas recycling scrubbers and water wash systems. In the end, however, the goal is to draw off the valuable fractions, the jet fuels and premier diesel products that were formed through the hydrocracking process.

In engineering terms, this is an extremely hostile internal environment, one that requires fabrication excellence. Top-tier vessel designs endure while corrosive compounds catalyse in high-temperature containment units. Extreme pressure variances exist in here, and the fact that the dangerous processing environment relies on hydrogen as a feedstock separator only underscores this hazard factor. Fortunately, a premier fabrication facility builds this four-part vessel framework with meticulous skill so that the hydrocracking process always functions within design specs.

Contact Details

Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619

1865 Frankston Flinders Road,
Hastings, VIC 3915

Ph: (03) 5909 8218

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