As we all know, due to the water ring vacuum pump and water ring compressor has the advantages of simple structure, easy to use and maintain, so it has been widely used in all walks of life. Especially with the characteristics of isothermal compression, easily sucked, compressed flammable gases. Here to talk about its development and design and development of a few superficial views. Large-scale As the coal, chemical, pharmaceutical, paper and other industries, the requirements of the water ring vacuum pump to more and more large-scale development. Before 2000, our country was able to produce only 3-4 enterprises in the water ring vacuum pumps with the pumping volume of more than 100m3 / min. The annual output of the country is only a few dozen or so units. And only three years later, by 2003 the country can produce more than 100m3 / min large pump manufacturers more than 10 (only Zibo area there are 7--8), according to incomplete statistics, the country's large pump The production of several hundred units or more, these products are mainly used in: (1) the coal mining industry as the country to strengthen the safety requirements of coal mines, and therefore the use of water ring vacuum pumps, especially large water ring vacuum pump gas extraction has become a necessary safety in the coal industry Requirements, such as last year, a mining bureau in Shaanxi ordered more than 400m3 / min pumping large water ring vacuum pump is used to extract gas, and some large coal mines use a large pump above 100m3 / min up to 7- -8 Taiwan. As the state further strengthens its safety work, large-scale and extra-large water ring vacuum pumps will be more and more widely used in coal mining systems. In addition, due to the rapid increase of coal production, the vacuum filter used in coal washing and coal preparation also went large-scale development. In the 1980s, most SZ-4 water ring vacuum pumps with a pumping volume of 27 m3 / min It was also larger at that time. In recent years, the coal mine filter are equipped with a large amount of pumping capacity of 80-150m3 / min water ring vacuum pump, and some reached more than 200m3 / min, but also the gas volume continues to increase. (2) Chemical Industry a) Chlor-alkali Industry In recent years, China has launched many large-scale capital construction projects and technological renovation projects. The actual children of these projects require a large amount of PVC materials, especially real estate, and have further promoted the production of polychlorination The development of ethylene industry, according to the statistics of the chlor-alkali industry, China produced 4.1 million tons of polyvinyl chloride last year and 200 tons of imported materials. According to the forecast of the industry, the national demand in 2005 will reach 8 million tons, and by 2010 it will reach 15 million tons precisely because of the rapid increase in demand, making China's chlor-alkali industry enterprises to expand production expansion and near One or two years a lot of new businesses. The development of chlor-alkali enterprises, water and air pumps and water ring compressor must be supporting j to extract and compress acetylene and hydrogen water ring vacuum pump and water ring compressor in the past but also the largest 30m3 / min, and now with an annual output of 100,000 tons Caustic soda and 100,000 tons of PVC companies need water ring vacuum pump and water ring compressor up to 70m3 / min. What needs to be specially introduced here is precisely because of the development of this industry, to promote and speed up the development and production of high I-force water ring compressors. For a long time, China's water ring compressor is generally when the suction pressure is 1 atm or slightly lower than the pressure, excluding pressure O. 1MPa, that is, the compression ratio is 2, and some enterprises have produced water ring compressors with the pressure up to 25MPaG, and only 1-2 specifications. In order to adapt to the production of polyvinyl chloride, the former major equipment office of the State Council proposed in the "85" major technological equipment research project - the research and development of an equipment with an annual output of 4 tons of low polymerization degree polyvinyl chloride device Research topics, this recovery of vinyl chloride monomer water ring compressor requires suction pressure at atmospheric pressure or micro negative pressure, the discharge pressure to reach O.55-0.6MPaG, and the displacement to reach 700m3 / min. After several years of hard work, our company passed the technical appraisal organized by the former Ministry of Machinery Industry in December 1996, and the customer technology has reached the key requirements. On the basis of this product, our company has developed a series of products, displacement from 90m3 / min to 2000m. / H. Since this equipment is one of the key equipment in the PVC industry, under the circumstance of the large PVC project in China in recent years, the water ring compressor has been popularized and applied, completely replacing the import. b) Fertilizer Industry The fertilizer industry, especially the production of phosphate fertilizer, is also a key support industry in China's macroeconomic regulation and control. As the technical renovation of new projects and old enterprises are above the level and scale, the large and extra large water ring vacuum pumps This has also been applied, such as a phosphate fertilizer company in Yunnan to a new increase in pumping capacity of 300m3 / min 3 large water ring pump. In addition, there are many technological requirements of phosphate fertilizer companies in the pressure of absolute pressure 80 - lOOhPa, still have a larger pumping capacity, so two water ring vacuum pump and air ejector with two water ring vacuum pump used here Under various operating conditions, it has unique advantages. Many chemical fertilizer companies eliminated the reciprocating vacuum pumps with large vibration and high vacuum and replaced them with two-stage water ring vacuum pumps, and received good results. It can be said that the two levels of water rings Vacuum pump applications in the industry will be more extensive. c) Paper industry At the end of the last century and the beginning of this century, China's national debt was heavily invested in the paper industry. Paper mills across the country were scrambling to upgrade the scale and scale of their operations, which greatly boosted the development and production of large-scale water ring vacuum pumps. A transformation of a paper mill in Northeast China 400IIl3 / min pumping large water ring vacuum pump (currently the largest production of water ring vacuum pump) 6, with a total power 400kW. It can be said that in recent years, the pumping capacity of more than 100m3 / min 50% of large water ring vacuum pump is used in the paper industry, and this trend continues unabated. d) Concentration, vacuum dehydration, drying and distillation in the pharmaceutical industry are the main processes of the pharmaceutical enterprises. The technological transformation of the pharmaceutical enterprises is equally on the upper level and on the scale, which is more obvious in some large pharmaceutical companies. In the past, most of them used small pumps of less than 10 m 3 / min, and now large and medium-sized pumps account for the majority of the project bidding in these enterprises with an extraction volume of more than 20 m 3 / min. In addition, many plants in the pharmaceutical industry used to have more two-stage water ring vacuum pumps with a suction volume of 6 - 12 m3 / min, and now both have 20-30 m3 / min two-stage water ring vacuum pumps and some also reach 60 m3 / min For example, a joint venture pharmaceutical factory in Sichuan last ten bid to buy 10 pumps with a pumping capacity of 60m3 / min last year. In addition to the above industries, the vacuum systems of light industry, food industry, beer industry and metallurgy, power generation, petrochemical and building materials industries all develop to large scale. For example, a certain aluminum plant in Shandong has long been using multiple water rings with an extraction volume of 85 m3 / min Vacuum pump, and last year's technical transformation project bidding equipment required water ring vacuum pump exhaust volume to reach 140m3 / min. 2 Completeness It should be said that in 2000 before the domestic water ring vacuum pump manufacturers are almost all single pump sales, very few users set complete sets of equipment, and the past two years, chemical, pharmaceutical industry, technical transformation project equipment Bidding equipment in a larger and larger proportion, the general requirements with splitters, coolers (heat exchangers), rehydration pumps, valves, meters, fittings and control devices, the formation of closed loop, and the requirements and corporate OCS System connected to the level, pressure, power and other online control. The requirements for such mechatronic plants are becoming more common in many industries. 3 higher vacuum requirements of a larger amount of vacuum pumping Many chemical and pharmaceutical industries vacuum distillation, concentration, dehydration, drying and power plant extraction exhaust requires suction pressure of 3 - 8kPa have a larger amount of exhaust , Single-stage water ring vacuum pump pumping capacity in this area has been quite weak, and two-stage water ring vacuum pump and a two-stage air ejector water ring vacuum pump is characterized by a larger intake in this range, Before 2000, the demand for two-stage pumps was mostly below 15m3 / min and now up to 40-50m3 / min. In addition, it should be noted that a single-stage water ring vacuum pump with a stage air ejector, if the design is reasonable, the suction pressure of 4 - 5kPa still have a larger pumping capacity, which greatly expanded the single-stage water ring vacuum pump Use, such as China's aircraft Institute on the use of such pumps more than one. In summary, it can be seen that the water ring vacuum pump and water ring compressor as a rough rough vacuum access to equipment has been widely used in various industries, it can be said that the rapid development of various sectors of the national economy to promote the water ring vacuum pump and Water ring compressor development and production. Therefore, in order to make it better adapt to the development of various industries, the following points of superficial view are put forward on the research and development of this pump. (1) Improve the reliability of MTBF water ring vacuum pumps and water ring compressors with feasible designs and high performance seals, that is, mean time between failures (MTBF) and other Compared to rough low vacuum equipment is still higher, the average trouble-free operation up to 10,000 hours or more. However, with the enhancement of technological progress in various industries and the increase in the reliability requirements of the entire vacuum system, the reliability requirements are also correspondingly higher. Especially in such chemical and coal mine gas under such stringent safety conditions, the pump to long-term continuous operation, the international advanced level up to tens of thousands of hours or more. Therefore, water ring vacuum pump and water ring compressor design work of the development and manufacturing conditions and seals (especially mechanical seals) the quality of the status quo to truly improve the reliability of the machine still need to further the above aspects Work to further strengthen. (2) The use of optimized design methods, efforts to improve the efficiency of the pump to reduce energy consumption Water ring vacuum pump and water ring compressor is a high energy consumption, low efficiency products, it is generally accepted fact that the small pump is generally 30-35% Large pump up to 40% or slightly higher, so low efficiency and the state's requirements for mechanical and electrical products and our current energy shortage situation is extremely incompatible. Therefore, the optimal design method should be used as soon as possible to establish the mathematical model of the geometric parameters of the impeller and the initial position and area of ​​the suction and exhaust holes, which affect the efficiency of the pump, to optimize the design, select the best combination of the parameters and adopt The theory and calculation formula of vapor-liquid two-phase flow are designed to minimize the eddy current loss of the water ring and achieve the purpose of improving efficiency. So as soon as possible design and development of energy efficient water ring vacuum pumps and compressors to eliminate high energy consumption, low efficiency of backward products is placed in water ring vacuum pump design and development, production enterprises in front of an important task. (3) Increase the amount of gas at the point of operation with the air ejector. Abroad, whether single-stage water ring vacuum pump or two-stage water ring vacuum pump with air ejector to improve the suction pressure at lower suction pressure situation is still more. From the technical information of advanced foreign enterprises can be seen on the single-stage water ring vacuum pump with a stage of the air ejector, the suction pressure of 5kPa point, the suction rate up to the pump without air injection suction pressure of 400hPa Point pumping speed (common user of the single-stage water ring vacuum pump of the total points) of 65 - 70%, two water ring vacuum pump with a stage of the air ejector, the suction pressure of 1.5kPa point pumping rate can be Up to 70 - 75% of the pumping rate of the suction pressure of 8 kPa (common working point of two-stage water ring vacuum pump) without the air ejector, thus greatly expanding the application scope of the water ring vacuum pump, that is, Meet the chemical, pharmaceutical, light industry, equipment, metallurgy, power generation and other industries require suction pressure 1.5 - 5kPa point pumping rate of the process conditions. At present, however, the domestic one is the application of water ring vacuum pump with atmospheric ejector is not widely enough; the second is the pumping speed at 1.5 - 5kPa point smaller, with the advanced technology level of foreign manufacturers have a certain gap. To further promote the application, we should study to improve the design of the air ejector and the optimal ratio of the water ring vacuum pump. Since the air flow in the taper of the nozzle of the air ejector (Laval nozzle) and the diffuser is supersonic The exchange of momentum in the process of mixing the two streams of air and gas to be drawn is complicated and can not be completely relied on the theoretical calculation method. Therefore, it is necessary to carry out many experiments. However, the application of the water ring vacuum pump and its efficiency From the perspective of strengthening the pilot study, and strive to improve its pumping efficiency.
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