The compressor gas seal structure is mainly composed of a sealing ring, a baffle plate, a retaining ring, a pressing ring and a spring. When the sealing ring is worn, the spring force compensates the wear of the sealing ring through the pressing ring. As the seal of the structure wears, the spring force compensates for wear of the seal by the compression ring. The improved steam blockage seal should take into account the changes in the working conditions of the machine when determining the pressure of each chamber. In the operating range of the compressor, no matter what happens, there should be room for gas leakage outside the machine. When the suction pressure of the compressor fluctuates, the steam pressure in chamber b must change accordingly, and the pumping capacity of the air extractor in chamber c must be changed accordingly, that is, the design of the air extractor should use a wider operating range.

The material selection of the labyrinth seal is determined according to the usage. In the catalytic cracking unit, the gas transported by the air press contains hydrogen sulfide, and the material of the labyrinth seal should avoid the use of copper alloy. According to the temperature condition of steam (about 254 °C), the inner labyrinth seal is made of stainless steel, and the atmospheric side can be made of cast aluminum.

The aspirator and steam flow control block the flow of steam with orifice control, which is simple and reliable. The power gas used in the aspirator can be rich in medium pressure steam in the refinery. The pressure should not be less than 0.8MPa. The air and water vapor extracted by the aspirator can be vented to the torch. If the temperature of the steam is too high, the material of the labyrinth seal will be selected as a problem. In addition, the shaft is bent after being locally heated, and thus causes vibration problems. When high temperature steam is used for this purpose, the blowing points should be evenly distributed along the circumference. Each sealing chamber shall be provided with a drain valve to exclude condensate. Since blowing steam generally produces condensate on the wall, it is necessary to consider the sewage disposal measures.