Compressor unit

A compressor unit that is a reciprocating compressor unit that recovers hydrogen gas that is boil-off gas from a liquid hydrogen storage tank and supplies at least a part of the hydrogen gas to a demand destination that includes at least one of an engine, a power generation facility and a boiler, the compressor unit comprising:

• a plurality of compression stages configured to compress hydrogen gas suctioned from a suction flow path;
• a crank mechanism configured to drive the plurality of compression stages;
• a cooler arranged in an intermediate flow path between the plurality of compression stages;
• a first switcher configured to switch an inflow state of hydrogen gas into the cooler;
• a spillback unit including a spillback flow path for returning hydrogen gas after being discharged to a discharge flow path on a discharge side of the plurality of compression stages or hydrogen gas flowing through the intermediate flow path to the suction flow path, and a spillback valve that adjusts a spillback amount in the spillback flow path;
• a first temperature sensor arranged in the intermediate flow path;
• a second temperature sensor arranged between a connection portion of the spillback flow path and a first compression stage as a foremost stage among the plurality of compression stages in the suction flow path;
• and
• a controller configured to control each of the first switcher and the spillback valve, wherein
• each of the first compression stage and succeeding compression stages excluding the first compression stage among the plurality of compression stages includes:
• a cylinder unit;
• a piston;
• a piston rod connecting the piston to the crank mechanism;
• and
• rod packing that seals between the piston rod and the cylinder unit,
• the first compression stage is of an air cooling type and an oil free type,
• wherein the controller is configured to:
• control the first switcher to establish a first switching state in which hydrogen gas discharged from the first compression stage is caused to flow through the cooler to be cooled at time of startup and in a case where temperature TS1 obtained by the first temperature sensor is equal to or more than a predetermined first temperature threshold T1 higher than 0° C.,
• control the first switcher to establish a second switching state in which hydrogen gas is sent to a compression stage downstream of a portion where the cooler is arranged without passing through the cooler in a case where the temperature TS1 obtained by the first temperature sensor becomes less than the first temperature threshold T1, and
• refers to suction temperature TS2 obtained by the second temperature sensor and control the spillback valve such that the suction temperature TS2 falls within a predetermined temperature range in a case where the first switcher is in the second switching state, and
• the predetermined temperature range is set to a range higher than reference temperature based on liquefaction temperature of air and less than 0° C..