The development of screw air compressor
Since the advent of screw compressors in 1934, after decades of technological improvement, screw compressors have been widely used, especially in refrigeration. Because screw refrigeration compressors and piston refrigeration compressors have the characteristics of simple structure, fewer wearing parts, long overhaul period, high volumetric efficiency, low exhaust temperature, insensitivity to liquid hammer, and stepless adjustment of cooling capacity, etc. Therefore, screw refrigeration compressors are more and more appreciated by users; and are widely used in various sectors of the national economy where artificial refrigeration is required, such as the production and scientific research of industrial products such as petroleum, chemical, light industry, and medicine. Low-temperature testing of food and aquatic products, low-temperature processing and storage of food and aquatic products, and air conditioning of large buildings such as public places.
... China jointly designed and produced the first oil-injected screw refrigeration compressor in 1976. At present, Yantai Binglun Group Co., Ltd., Dalian Refrigeration Co., Ltd., Wuhan New World Refrigeration Industry Co., Ltd. and many other manufacturers have been able to produce screw-type refrigeration compressors. The nominal diameter of the rotor ranges from 91mm to 315mm. The standard working condition (-15℃) /30℃) The refrigeration capacity ranges from 38kW to 2470kW , and two series of screw refrigeration compressors of open type and semi-closed type have been formed. This article combines the status quo of screw refrigeration compressors made in China and analyzes the development trend of screw refrigeration compressors made in China for your reference.
The current situation of screw refrigeration compressors made in China
... Since the successful trial production of my country's first screw refrigeration compressor in 1976, after more than 20 years of technological transformation, there has been a great improvement, but there is still a certain gap compared with the international advanced screw refrigeration compressor.
At present, the world’s recognized high-efficiency molding lines include the Sigma type line of KASSER, the CF type line of GHH, and the 56U type line of Hitachi. Most of the existing major screw refrigeration compressor manufacturers in my country use standard profiles (asymmetric arc cycloid tooth profile), part of Dalian Refrigeration Co., Ltd. D87 new tooth profile, and part of Wuhan New World Refrigeration Industry Co., Ltd. The model is XBY type line, although its efficiency is higher than the standard type line (5%～10%), but compared with international (10%～20%), there is still a certain gap. Therefore, China's new and efficient rotor profile has yet to be further developed.
The high operating noise of screw refrigeration compressors is a major obstacle restricting the scope of use of screw refrigeration compressors. According to the relevant regulations of GB12348-90 "Noise Standards at Boundaries of Industrial Enterprises" and GB3096-82 "Ambient Noise Standards in Urban Areas", the noise range of screw refrigeration compressors made in China is 76db(A)～112db(A). It does not meet the relevant regulations of the national noise standards.
Oil separation efficiency
At present, the oil separation system of China-made screw refrigeration compressors is relatively large, and the problem of low oil separation efficiency is common. The oil separation efficiency of similar international products has reached 99.999%. So far, we have only found new oil separators newly developed and produced by Yantai Binglun Group in the relevant information. Its oil separation efficiency is 99.998%, which is comparable to international products.
At present, the reliability of China-made screw refrigeration compressors is poor, which is mainly manifested in: the slide valve cannot be held in place; the shaft seal has poor reliability and short life; the energy indicator has sealing and tightening problems; the quality of the electrical components of the control system is unstable, etc.
The content volume ratio is adjustable
The current Chinese-made screw refrigeration compressors, except that Wuhan New Century Group Co., Ltd. has adopted manual content volume ratio adjustable devices in some models, other manufacturers are equipped with three different content volume slides according to different operating conditions. Valves are available for users to choose. However, because the conditions of use are not static, if one type of spool valve is selected, it will cause over or under compression of the screw refrigeration compressor, which increases the power loss of the screw refrigeration compressor and reduces the performance index.
In recent years, international screw refrigeration compressors have adopted an intelligent microcomputer control system, which is easy to operate, on the other hand, saves energy, and has high reliability and easy cooling capacity adjustment. However, most of the screw refrigeration compressors produced in China are manually operated, and the control functions are mostly protected by relays, which are not easy to operate, save energy, and have poor reliability.
The application of screw refrigeration compressors in the field of heat pumps In the world, screw heat pumps have been widely used. The heat supply is 10 to 5 million kcal/hour, and the heating temperature is 10℃～56℃, 70℃ and 150℃. The application and research of is still in its infancy. At present, Dalian Refrigeration Co., Ltd. has developed two types of screw heat pump units of RBKF12.5 and RBKF16, and the heating temperature can only reach 50℃～60℃