Oil-flooded screw compressor system and method for modifying the same

A method of modifying an oil-flooded screw compressor system for compressing a gas to be compressed which is compatible with lubricating oil, the oil-flooded screw compressor system comprising:

• a screw compressor which includes:
• a male screw rotor and a female screw rotor each having a screw part and shaft portions formed on both ends of the screw part;
• a housing having a screw chamber accommodating the screw parts inside and a bearing chamber accommodating the shaft portions inside;
• and
• a bearing disposed in the bearing chamber, for rotatably supporting the shaft portions;
• a first lubricating oil supply system for supplying lubricating oil to the screw parts;
• and
• a second lubricating oil supply system for supplying the lubricating oil to the bearing,
• wherein the first lubricating oil supply system includes:
• a gas-liquid separator configured to introduce discharge gas of the screw compressor therein and to separate the lubricating oil from the discharge gas;
• a first supply flow passage formed through a housing wall which constitutes the housing, the first supply flow passage having an opening on an outer surface of the housing wall and being in communication with the screw chamber;
• and
• a first supply path connected to a lubricating-oil storage region of the gas-liquid separator and to the opening of the first supply flow passage, and
• wherein the second lubricating oil supply system includes:
• a second supply flow passage formed through the housing wall, the second supply flow passage having an opening on the outer surface of the housing wall and being in communication with the bearing chamber;
• a second supply path connected to the opening of the second supply flow passage;
• and
• a single second discharge flow passage formed through the housing wall and being in communication with the bearing chamber and the screw chamber,
• the method comprising:
• a first step of forming a third discharge flow passage by forming a linear through hole through the housing wall to communicate with the second discharge flow passage and the first discharge flow passage, the linear through hole including a flow passage which is a part of the first discharge flow passage and which has an opening on the outer surface of the housing wall, the linear through hole having openings into the screw chamber and on the outer surface of the housing wall via the second discharge flow passage and the flow passage;
• a second step of connecting a discharge path to the opening of the third discharge flow passage on the outer surface of the housing wall;
• a third step of closing the opening of the second discharge flow passage on a side of the screw chamber with a first closure member;
• and
• a fourth step of connecting the discharge path to a lubricating oil reservoir connected to the second supply path.