The BP Chemicals Polymer Cracking Process

BP Chemicals has led promotion of a liuidized-bed cracking process that could be used to convert plastic waste into petrochemicals. The Polymer Cracking Process was first tested on a laboratory scale and then on a continuous pilot scale (having a nominal 400 t/yr capacity) at BPs Grangemouth site in the UK. 

---

A number of cracking/depolymerisation processes are currently operating commercially. These include the Texaco gasification process and the BP Chemicals polymer cracking process. Both have been operating since the mid 1990s. 

The BP Chemicals polymer cracking process is based at Grangemouth in Scotland and uses mixed plastics as the raw material. The reactor uses a fluidised bed which operates at 500 °C in the absence of air, and under these conditions the plastics crack thermally to yield hydrocarbons. These vaporize and are carried away from the bed with the fluidising gas. Solid impurities such as metals from PVC stabilisers accumulate in the bed or are carried away in the hot gas to be captured by a cyclone further along in the plant. PVC decomposes to HCl and this is neutralized on a solid lime absorbent to yield CaCl2 which is disposed of in landfill. The purified gas is cooled to condense most of the hydrocarbon which can be employed as commercially useful distillate feedstock. The light hydrocarbons which are less easy to condense are compressed, reheated and recycled as fluidising gas. 

---