I think it is very common to have a naphtha wash available to inject into the wet gas compressor. I have heard that some sites inject naphtha continuously, others inject intermittently while others do not inject naphtha during the course of the run.
I think the conventional wisdom is the naphtha injection helps to prevent polymerization of the dienes in the wet gas. If the temperature of the compressor discharge is higher than 300 F (150 C), there is a risk of polymerization. My understanding is that this is a common problem in ethylene plants that have a much higher olefin content in the gas stream. In those cases, they try to limit the compressor discharge temperature to less than 240 F (115 C) to prevent that polymerization and injection of a liquid into the compressors helps prevent that problem.
Each installation is different as the performance of the overhead accumulator to separate liquid and vapor is different at each unit and the compressor design is different for every site. The temperature of the overhead accumulator determines the amount of heavy hydrocarbons in the wet gas stream, which impacts the discharge temperature of the compressor. All of these could impact the need for naphtha injection into the wet gas machine.
