NCG Compressor Failure and Rebuild
Recently, a client reached out to S&S Technical to help them with the catastrophic compressor failure at their geothermal power generation plant. The failure was on their Non-Condensable Gases (NCG) compressor which is responsible for recovering the NCG from the vaporizer. Because there is the potential large amounts of liquid carry-over in this gas stream it is important there is a properly sized suction scrubber with a reliable drain system to prevent these liquids from entering the compressor. In this instance, a large slug of liquid was introduced to the compressor during operation which resulted in the failure.
The horizontal, single-stage, single-throw reciprocating compressor used in this application has very tight piston clearance tolerances. When liquid is introduced to the compressor cylinder – in a large enough volume, there is not enough space left in the cylinder at top-dead-center to accommodate it. The liquid is incompressible and, as a result, a tremendous amount of hydraulic pressure is created and transmitted through the rotating member. In this instance, the amount of pressure far exceeded the rated load capacity of the connecting rods and crankshaft. This intense rod loading caused the connecting rods and cranks shaft to break as well as separated the compression piston from the piston rod.
