Quote Cart
In the Visbreaker, the residues from the VD‐500 are thermally cracked. In exceptional cases, the atmospheric residue of the D‐500 can also be used. The VBU consists of two strings, each capable of processing 80 t/h of vacuum residue.
In the VBU, long-chain hydrocarbons are broken up by the action of temperatures in the range of 400 °C to 500 °C. As a result, the residue of the VD‐500 mixing components is recovered in the boiling range below 400 °C. Since the splitting reaction that takes place results in a reduction in the viscosity of the residue used, the system is called a "visbreaker" or viscosity breaker.
The vacuum residue used is heated to a maximum of 450 °C in the L2‐A and L2‐B furnaces with the heating agent 8 bar heating gas (the ignition burner is operated with natural gas). At a pressure of 10 bar, the residue in the so-called soaker is exposed to the reaction conditions for a defined period of time.
The reaction product is then expanded, cooled to below 400 °C and further processed to separate the hydrocarbons formed in atmospheric distillation N‐1 and vacuum distillation N‐2A. In the N‐1, the head product is a cracker gas is obtained, which is directed to the head gas of the D‐500. The upper side fraction is a crude cracker gasoline that is fed to the HDS (1200) kerosene desulphurization plant. A cracking gas oil (KGO) is produced as the lower side fraction, which is piped to the MDH. The swamp product of N‐1 is directed to N‐2A.
At a pressure of 10 mbar to 20 mbar, a cracking light distillate (KLD) is extracted from the N‐2A as a head product, which is fed to the T124 tank. A cracker vacuum distillate (KVD) is obtained as a side fraction, which is fed to tank T121 (additional component to HCU's application product) and/or as a flux agent for the cold residue to the input tank O‐38 for flux oil in the VBU.
The swamp product of N‐2A is formed, the so‐called visbreaker residue, which is cooled and used as an input product for oil gasification, as a sales product or as a mixed component for heavy heating oil. In the latter case, the Visbreaker residue is mixed with a flux agent KGO, KVD or a flux component from tank T55 or a mix of all of the above. This causes a further reduction in viscosity, so that the residue remains liquid even at temperatures below 100 °C.