RAISING EFFICIENCY OF PLATE-AND-FIN OIL COOLERS FOR SCREW COMPRESSOR PLANTS

摘要

Mobile plants having screw compressors are widely used in shaft and open-pit mining. Aside from reduced cost of compressed air production, screw compressors ensure reliability and durability of compressor plants. A distinctive feature of screw compressors is use of oil for sealing running clearances in screw couples and for simultaneous removal of the heat generated upon compression of the gas. In this case, oil flow of 5-7 liters/min and removal of 5-7 kW of heat flux is required to compress 1 m~3 of air to 0.8 MPa pressure. Some characteristics of series-produced screw compressor plants are listed in Table 1. For oil cooling, in the plants made by the OAO NPAO VNIIkompressormash use is made of plate-and-fin heat exchangers (PFHE) which are of a multi-layered soldered structure of thin aluminum or steel sheets and strips. Aluminum alloys are the conventional material for PFHE making, but for a variety of reasons their use for mobile screw compressor plants is limited. The main reasons are corrosion and erosion failure of aluminum alloys in environments of underground operation and in dusty open pits. Steel PFHEs, including those having channels from corrosion-resistant steels, are more reliable. The reliability and life of the PFHEs can be increased by using corrosion-resistant steels. Nickel-free, chromium, and fenitomartensitic steels are preferable. They possess fairly high corrosion resistance in compressor plant operation conditions and are twice as strong as widely used chromium-nickel steels.