Debugging of a Vinyl Chloride Recovery Unit

Illustration 9.3 Debugging of a Vinyl Chloride Recovery Unit 

Vinyl chloride monomer (VCM) is a volatile substance (boiling point 14dC) used as a starting material for the production of polyvinyl chloride (PVC). It has been identified as a potential carcinogen, and occupational health regulations now call for an upper limit of 1 to 5 ppm VCM in factory air. 

A preferred method of air purification is to pass VCM-laden air through beds of activated carbon. These beds operate on a four-step cycle  

Stripping of the adsorbed VCM with steam, which is subsequently condensed, leaving essentially pure VCM that is dried and recycled 

A dual-bed system is commonly employed, so that while one bed is onstream, the second bed can be regenerated and prepared for the adsorption step. The time period allowed for each step is typically as follows  

---