As a positive displacement compressor, the screw compressor is ideal for handling the relatively light hydrogen rich gas. Compared to a centrifugal compressor, higher pressure ratios can be reached in one single stage. If the feed gas comes out of a styrene monomer unit or a coke oven plant, the screw compressor can easily be equipped with liquid injection. Offering a reliability which is similar to that of turbocompressors, process-gas screw compressors have availability figures of up to 99% over a large number of operating years.