A fluid catalytic cracking unit (FCCU) is used for converting heavy crude oil into lighter petroleum products. These products include liquefied petroleum gas and gasoline. The chemical process used for conversions is known as cracking, one which entails breaking down large hydrocarbon molecules into smaller ones.
An FCCU is constructed in such a way that these massive hydrocarbon molecules are exposed to a catalyst and high temperatures to initiate their disintegration. Common catalysts include zeolite, aluminium hydrosilicate, bauxite, and silica-alumina. When the FCCU process is complete, the product is sent to the hydrocracker for further processing.
The fluid catalytic cracking units were introduced back in 1940 and since then, they have continued to improve the efficiency and output of many refineries. Let’s learn some interesting things about FCCUs.
What Happens in the FCCU Process?
During this process, gas oil gets pre-heated in drums and pumped into the reactor generator or the riser. The reactor generator provides contact between the gas oil and catalyst, which are then atomized to the stripper. A great example of this are the chemical reactor manufacturers in India that explicitly help refine petroleum.
The steam in the stripper under controlled temperature and pressure helps separate the spent catalysts from the liquid hydrocarbons. As a result, the spent catalyst levels are maintained in the stripper and the re-generator.
The re-generator then purifies this catalyst and channels it back to the reactor generator. This helps maintain the required amount in the FCCU. The hydrocarbon vapours then flow into the central column, which condenses the vapours into trays.
The vapour in the main column is de-superheated while cooling to wash away whatever spent catalyst is left inside. Further distillation and refining help produce gasoline and diesel. Fluid Catalytic Cracking is a complex but fundamental process in the petroleum industry. It transforms high boiling and low-value gas oils into valuable, lightweight oils.
What Products are Produced in the FCCU?
The FCCU produces various lighter products, the main one being FCC gasoline. The FCC Gasoline is the largest product comprising about 50% of overall FCC output. It’s a naphtha range material with octane and vapour pressure and quality specifications for finished gasoline.
Other products include:
· Cycle Oils
The FCCU produces a diesel range of products called cycle oils. However, they are high in sulfur, making them a poor diesel blendstock.
· FCC Gas
The fluid catalytic cracking unit’s light ends include saturated and unsaturated C3s and C4s.
· FCC Slurry
It is the heaviest product from the FCC, often high in sulfur. It’s sent for fuel blending and used as a feeder for the coker. It makes products such as carbon black and needle coke.
What are the Key Benefits of FCCU Refractory Linings?
Petroleum refineries need refractory solutions that offer the advantage of insulation and abrasion resistance for FCCU. It helps improve efficiency and reliability in the production of gasoline and diesel. With the increasing demand for transportation fuel, advanced refractory solutions have a few benefits. These are:
- High abrasion resistance
- Exceptional thermal insulation
- High thermal shock resistance
- Consistent thermal reliability at high temperature
- Reduced energy consumption
- Lesser maintenance costs
- Resistance to acid corrosion
The fluid catalytic cracking unit is not a new term in petroleum refineries. Over the years, many improved FCC designs have evolved as cracking catalysts. However, the modern FCCUs are still the same as the first model FCCU ever used.