The screen surface of a roller screen is composed of many parallel arranged rollers with staggered screen plates, and the gap between adjacent rollers and disks is the sieve hole of this type of screen. The roller rotates through sprocket or gear transmission, and its rotation direction is the same as the direction of material flow. Roller screen is often used for screening coarse materials and is suitable for screening soft and medium hard materials. Its advantage is that it does not block the screen.
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According to statistics, a medium-sized refinery has more than 1,000 pumps, of which 83% are centrifugal pumps, 6% are reciprocating pumps, 3% are gear pumps, and the rest are screw pumps and vacuum pumps. A petrochemical plant has more than 2,000 pumps, of which centrifugal pumps account for 45%, gear pumps for 23%, reciprocating pumps and screw pumps for 12%, and shielded pumps for 6%. These pumps are generally driven by motors.
The petrochemical pump conveys medium pressure from negative pressure to 300 MPa, temperature from minus 140°C to nearly zero at 500°C, some medium is viscous, some still have solid particles, and most of the transport medium is corrosive. The petrochemical pump is the most energy-consuming equipment. The pump power consumption accounts for about 50% of the total power consumption of the whole plant.
With the continuous development of petrochemical industry technology and scale, the demand for petrochemical pumps is increasing. In addition to continuing to increase the quality of conventional pumps and expand the variety of specifications, the demand for pumps for the transport of corrosive materials is increasing, such as ethylene crackers, polyethylene units and polypropylene units in ethylene production; in chemical fiber production PTA device (pure terephthalic acid), polyester device and polyester spinning device, acrylonitrile and fat feeding device. Therefore, efforts should be made to develop corrosion-resistant pump technology.
At present, the materials of corrosion-resistant pumps are still largely made of ferrous materials and high-nickel alloy materials. In the future, they are required to use more excellent corrosion-resistant materials such as titanium, zirconium, and hafnium, as well as non-metallic materials such as ceramics, fiberglass, and graphite. .
China's petrochemical industry will have a big development during the 10th Five-Year Plan period. Its production technology and scale will be in line with international standards. Sinopec and PetroChina will invest nearly 100 billion yuan each year, and the demand for petrochemical equipment will be very high. of.
Petrochemical pumps are also the most used rotating equipment for petrochemical production, and their performance, quality, and longevity will have a great impact on petrochemical production and construction. The domestic pump industry should speed up the pace of reforms, aim at this largest market, carry out product structural adjustments, and improve the level of technology and management. First, we must improve the standardization, serialization and generalization of products.