Large-scale petrochemical plants have caused large-scale production of related products such as pumps, valves, and compressors. As a key equipment in the petrochemical industry, compressors, in recent years, although they have made breakthroughs through the introduction, digestion, absorption, and innovation, there is still a certain gap compared to the advanced level in foreign countries. Then, in the face of the development trend of large-scale petrochemical plants, how should China's compressor industry catch up and advance to the international advanced level?
Development Trends In recent years, the scale of petrochemical production at home and abroad has continued to expand, and the trend of large-scale compressors has become apparent. Internationally, the atmospheric and vacuum distillation units in petrochemical production plants have reached 17 million tons/year, catalytic cracking units have reached 6.5 million tons/year, continuous reforming units have reached 2.45 million tons/year, and hydrocracking units have reached 3.5 million tons/year. In the year, the delayed coking unit reached 6.4 million tons/year, the ethylene cracking unit reached 1.27 million tons/year, and the polyethylene and polypropylene plants reached 500,000 tons/year.
After the development of the compressor industry in China in recent years, although the pattern of long-term monopolization of China's compressor market by foreign manufacturers has been broken, due to the gap in the development capability, manufacturing technology and management level of domestic compressor manufacturers, there is a certain gap The petrochemical industry also has 30% of centrifugal compressors and 20% of reciprocating compressors imported from abroad.
According to statistics, the compressors with a large number of imports are still concentrated in reciprocating ultrahigh-pressure compressors, reciprocating labyrinth compressors, and reciprocating diaphragm compressors in large-scale ethylene “triple machinesâ€, polypropylene plants, and polyethylene plants. For the screw compressor in the olefin extraction plant and the air compressor in the PTA plant, the PTA air compressor unit is more difficult to design. It is driven by a steam turbine and drives the air compressor and generator coaxially. And exhaust turbine.
Since the beginning of the 21st century, the single-scale scale of domestic refineries has started to grow from the previous 2.5 million to 5 million tons/year to the current 8 million to 10 million tons/year, and the single-scale scale of ethylene plants has started from the previous 110,000 to 300,000. Tons/year is now 800,000 to 1 million tons/year. At present, the largest petrochemical centrifugal compressor that has been put into use in China is a crack gas compressor in Shanghai Seker's 900,000-ton ethylene cracker. Its inlet flow has reached 260,000 Nm3/h, and the outlet pressure has reached 3.89 MPa, driven by a steam turbine. The shaft power reaches 45000kW; the largest petrochemical reciprocating compressor that has been put into use in China is an ultrahigh-pressure compressor in a 200,000-ton/year high-pressure polyethylene plant, with a mass flow of 85000kg/h and an outlet pressure of 310MPa, which is achieved by a synchronous motor. Drive, power up to 16500kW.
R & D direction As the scale of production increases, the capacity of the compressor is also increasing, but this increase in capacity is not simply to enlarge the equipment, but in the design theory, design calculation, machinery manufacturing and inspection and testing Many new topics have been proposed, and this change has also become a bottleneck in the localization of large petrochemical compressors.
In this regard, the international practice is to shift the focus of technological development to improving product reliability and operating efficiency, reducing energy consumption, improving production process methods, and electromechanical integration. In recent years, with the development of new technologies, the three-dimensional flow theory has been developed and applied to the design of impeller blades and diffuser and other stationary components. The efficiency of the compressor has been increased to over 88%, and the unit operation has been stable. The control level of detection, alarm and chain parking systems is correspondingly improved, and the continuous operation period of more than three years can be guaranteed.
In product design, compressor thermodynamics, dynamics calculation software and compressor working process simulation software are used to improve the accuracy of the calculation, and the performance parameters of the compressor under actual operating conditions are predicted through a comprehensive simulation model to improve the development of new products. The success rate of compressor products is enhanced by electromechanical integration. Computerized automatic control is used to automatically display various operating parameters, optimize energy-saving operation status, optimize on-line operation, abnormal display of operating parameters, alarm and protection; product design emphasizes industrial design and Environmental protection, the appearance of the compressor is beautiful, more in line with environmental protection requirements.
The key reciprocating compressors used in the petrochemical industry are widely used. With the rapid development of the industries such as oil refining, ethylene, and chemical fertilizers, the reciprocating compressors have greatly boosted the design and manufacturing level, and the maximum piston load of large-scale reciprocating compressors. It has been more than 1250 kN and the shaft power has exceeded 10000 kW. At present, reciprocating compressors are moving in the direction of large capacity, high pressure, compact structure, low energy consumption, low noise, high efficiency, high reliability, and strong exhaust gas purification capability.
Screw compressors are favored by petrochemical companies due to their small size, light weight, and easy maintenance. However, due to the high requirements on flow, discharge pressure, and shaft power of the compressor, it is still basically dependent on imports. For example, a butadiene screw compressor in an ethylene plant with a flow rate of 5,777 m3/h, a discharge pressure of 0.7 MPa, a shaft power of 590 kW, and solid powder in the medium. The regenerated gas screw compressor in the polyethylene plant has a flow rate of 1678 m3/h and a shaft power of 400 kW.
At present, the manufacturing technology of screw compressors in the world is undergoing rapid changes. In addition to continuously researching and developing high-performance screw new tooth types in order to improve the efficiency of the compressors, there has been considerable progress in structural design. In addition, equipped with a microprocessor-based processing device on the compressor can realize automatic monitoring, protection and control, and realize the integration of electromechanical devices.
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