Research and Practice of Localization of Gray Sludge / Gypsum Wet Flue Gas Desulfurization Metal Slurry Circulating Pump Wang Nahua 1 Lu Tianyi 21, Xiangfan 5255 Pump Industry Co., Ltd. of China Ordnance Group Xiangfan 4410212, Hubei, China HVDC Hangzhou Banshan Power Generation Co., Ltd. Hangzhou 310015, Zhejiang, China Abstract: This paper introduces the successful development of flue gas desulfurization metal slurry circulating pump in Xiangfan 525 Pump Co., Ltd. Including: pump hydraulic model, structure, mechanical seal, material research results, the industrial assessment and identification of the pump has reached the international advanced level, fully able to achieve China's 50MW to 600MW thermal power plant desulfurization unit of a variety of metal slurry circulation Pump localization. Keywords: metal slurry circulation pump, localization Introduction: Limestone (lime) / gypsum wet flue gas desulfurization process running reliability, adaptability to coal changes, is the world's most technologically mature and most widely used desulfurization Technology, but also China's thermal power plant flue gas desulphurization by the mainstream technology. According to incomplete statistics, a total of 159 flue gas desulfurization projects have been built and under construction in China, with a total installed capacity of 65 million KW, of which more than 130 sets are used for limestone / gypsum wet desulfurization and the total installed capacity exceeds 59 million KW. In the limestone (lime) / gypsum wet FGD plant, absorption tower circulation pump is the key equipment, known as "the heart of the plant operation." The pump is a large equipment, expensive transport medium both gypsum solid phase erosion, there is a high content of Cl- corrosion, the pump life, operating efficiency, safety and reliability and maintenance convenience High expectations. At present in our flue gas desulfurization equipment, all kinds of small and medium-sized
Slurry Pump has basically achieved full localization, and this large-scale circulation pump is still mainly imported. Xiangfan 525 Pump Co., Ltd. has nearly 20 years of wear-resistant anti-wear pump production experience, the exclusive introduction of the French company Jumont Schneider (J · S) corrosion resistant wear-resistant pump manufacturing technology and Haute Sambre (H · S ) The company's special corrosion-resistant wear-resistant alloy material smelting casting technology. With strong technical force, rich experience in design and manufacture of corrosion-resistant and wear-resistant pumps as well as keen market awareness, 525 Pump Company started to develop such a large-scale flue gas desulfurization circulating pump in 2000, Material development, efficient hydraulic design, pump design and seal technology development has made fruitful achievements. The flue gas desulfurization circulating pump developed by the company was identified as the national key new product by the Ministry of Science and Technology, the Ministry of Commerce, the State General Administration of Quality Supervision, Inspection and Quarantine and the State Environmental Protection Administration in 2004 and was supported by the National Science and Technology Innovation Fund for Small and Medium-sized Enterprises. China Huadian Group Hangzhou Banshan Power Generation Co., Ltd. is one of the first power plants in China to introduce the limestone (lime) / gypsum wet FGD plant. The circulating pump of this unit is imported from Germany KSB Company. Over the years Hangzhou Mid-Levels Power Plant has been seeking the pump localization, after investigation and study, the final selected Xiangfan 525 Pump Co., Ltd. as a recycle pump localization of relying on the plant. At present, a LC600 / 825 circulating pump produced by 525 pump companies has replaced the imported pump and operated smoothly at the station. The pump has been successfully manufactured domestically. First, the flue gas desulfurization slurry circulating pump technical requirements Absorber circulating fluid is a solid-liquid two-phase flow medium, the solid content of the slurry limestone and gypsum, the weight concentration is generally about 20%; coal-fired flue gas in the cycle of absorption process will The formation of sulfuric acid, hydrochloric acid and other acidic mixture, and gradually enriched with the extension of the cycle time, so the chloride content of the slurry is generally between 20000 ~ 60000PPm, PH is generally between 3.5 to 7. Complicated medium with high corrosive and high-speed flow poses harsh demands on the material of circulating pump. Therefore, slurry circulation pump overcurrent component material corrosion resistance and corrosion resistance is to determine the pump an important indicator of service life. According to the unit installed capacity and different sulfur content of coal, desulfurization absorption tower slurry circulation flow is usually between 4000 ~ 12000m3 / h, head in between 16 ~ 30m. According to statistics, in flue gas desulfurization capacity, slurry circulation pump power consumption, accounting for more than one-third of the desulfurization island power consumption, therefore, the large flow rate and high efficiency of the pump is an important technical requirements. Slurry circulation pump is a large equipment, limestone (lime) / gypsum wet desulfurization is one of the core equipment, expensive, safe and reliable pump maintenance and maintenance of convenience requirements are also high. Based on the above requirements, Xiangfan 525 Pump Company started from pump material development, hydraulic design, structural design and seal design and other aspects, the development of LC series flue gas desulfurization circulating pump. Throughout the development process of a small prototype trial, the authority of the product testing, prototype prototype, power plant industrial assessment process. Second, the research and development of slurry circulation pump slurry flow circulating pump overcurrent components used in terms of corrosion and wear-resistant technology, there are two main programs in the world, one is the use of cast iron housing, lined with rubber technology, rubber lining Pump; the other is the use of corrosion-resistant wear-resistant alloy pump over-current components, the alloy pump. The two technical solutions have advantages and disadvantages with each other, the use of alloy pumps, the initial investment cost is higher, but the pump device running reliability, long life, easy maintenance, users are more inclined to choose this program, in fact, from Japan, The United States to implement flue gas desulfurization experience point of view, the application of the alloy pump is relatively large. And Xiangfan 525 Pump Company has introduced the French special corrosion-resistant wear-resistant alloy smelting casting technology, the successful realization of the wet-process phosphoric acid plant in China-made anti-wear slurry pump, and wet process phosphoric acid slurry And limestone (lime) / gypsum wet FGD process slurry has a similar composition and corrosion erosion characteristics. Therefore, five five five pump industry in Xiangfan developed a flue gas desulfurization cycle pump option alloy pump program. 1, Development of Corrosion-resistant and Wear-resistant Alloy Materials Relative to the wet-process phosphoric acid process, the dialect and acidity, solid content and temperature of flue gas desulfurization slurry are small, but the chloride ion content is higher. The comparison between the two slurries is as follows: Item Acid Solid Content (ppm) Cl- (ppm) Temperature (° C) Flue Gas Desulfurization Slurry PH = 3.5 to 7 15 to 20% 104 to 106 20000 to 60000 45 to 55 Wet phosphoric acid slurry P205 H2SO4 30 ~ 35% ≤20000 ≤200 85 85% ~85% 3 ~ 5.3% The material of the wet-process phosphoric acid pump is imported from France with high-chromium corrosion-resistant alloy and duplex stainless steel. They are F30% CrMo (company code Cr30) and Z3CNUD2605M (company code 2605), both of which are still the most demanding materials for corrosion of corrosive abrasive wet-process phosphoric acid. For the flue gas desulfurization slurry chloride ion content characteristics, we introduced two kinds of material to be improved. Based on Cr30, Ni and Cu elements are added to improve the resistance to chloride ion corrosion. The improved material code is Cr30A. The material because of its high hardness, corrosion resistance and good corrosion resistance, used in the manufacture of slurry pump rotary
Impeller and the front and back with the shield and other parts. On the basis of 2605, the carbon content is reduced below the ultra-low carbon range (0.03%); the increased Mo content and the enrichment of Mo element in the passivation film close to the matrix improve the stability of the film and remarkably improve the porosity of the duplex stainless steel Etching performance, especially the passive film MoO2, the steel in a high PH value of the high concentrations of chloride in a good protective; at the same time adding N elements, improve the pitting resistance of austenite, thereby increasing the pitting of the entire material Resistance. Moreover, the N element can significantly improve the mechanical properties of the material, promote phase equilibrium and eliminate the adverse effect of increased brittleness tendency of the material due to the increased Mo content. Improved material enterprise code 2605N, the pitting resistance equivalent PRE value is greater than 40. The material has both good corrosion resistance and abrasion resistance, as well as good strength and toughness, so it is used to manufacture the pump body parts which are subjected to the liquid pressure and the pipeline external force. On the basis of ensuring the long life of the pump body, To ensure the safety of the pump. The two kinds of materials mentioned above were tested in the corrosion and abrasion test simulating the actual operating conditions in desulfurization circulating slurry medium taken from Luohuang Power Plant at the Institute of Foundry and Wear Resistant Materials of Xi'an Jiaotong University. The corrosion and wear of Cr30A and 2605N Rate of 0.46mm and 0.78mm, respectively, far exceeding China's initial application of desulfurization high alloy austenitic stainless steel 1.4539,1.4529 and other materials. 2, efficient hydraulic design Hydraulic line to determine mainly through the hydraulic screening, sample pump hydraulic model design, computer simulation flow field design calibration, model pump trial, hydraulic test several processes. In the process of hydraulic screening, the LC300 / 635 type line introduced by our company and specially used for the transmission of the two-phase flow medium is applied. However, considering that the original hydraulic model is designed for ore slurry transportation and is suitable for a wide range of slurry characteristics, The solids content of up to 65%, the maximum diameter of particles through 55mm, thus limiting the pump efficiency. The desulfurization circulating pump as a flue gas desulfurization special equipment, a single condition, little change, the maximum solids content of only 20%, of which the solid phase is also smaller. Therefore, we redesigned the pump tongue, blade thickness, flow area and other parameters, and the use of CFD (computer simulation of flow field design) technology to simulate the actual flow. By constantly adjusting the characteristic parameters until the CFD shows the best. According to the improved LC300 / 635 pump model, we made a trial model pump. The model pump has been inspected by the National Industrial Pump Quality Supervision and Inspection Center and issued a Pump Test Report with a flow rate of 1500m3 / h, a lift of 25m and a rotation speed of 740rpm When the efficiency is 82%. Achieve the same level of pump efficiency index of the international advanced level. On the basis of successful prototype pump, through the similar calculation and application of CFD (computer simulation of flow field design) technology, the hydraulic scheme of 600mm diameter pump was determined. The sample was completed in June 2004. After hydraulic test, the pump flow rate is 4800 m3 / h and the lift is 20.6m, the efficiency reaches 86%, which fully accords with the performance requirement of No.3 slurry circulating pump station in Mid-Levels Power Plant. The actual performance curve of the pump is basically consistent with the performance curve predicted by CFD. The actual value at the design point exactly matches the predicted value. 3. The main structure of slurry circulation pump design Considering the safety and reliability of the pump and maintenance convenience, the main use of the following several structural design. a. slurry circulation pump is a large flow pump, bulky, reducing the workload of maintenance is very prominent, so the "back door" structure, set in the coupling part of the middle section, remove the intermediate section during maintenance, leaving space, the entire bearing Components and impeller can be drawn from the rear, without having to remove the inlet and outlet pipelines. b. General set of liquid pumps before and after the mouth ring, and this pump replaced before and after the guard, both to ensure efficiency, but also easy to replace. c. In order to keep the pump running at high efficiency, the relative position of the impeller in the pump body can be changed through the adjustment of the bearing components. d. The use of a smaller aspect ratio (shaft thicker) to reduce the dynamic shaft deflection. To a certain extent, control the detrimental effect of shaft deflection on seal life. e. Selection of imported bearings, bearing housing with thin oil lubrication, improved bearing working conditions and improve the bearing life. Its structure is shown on the left. Metal slurry circulation pump Features Overview: a. Simple structure: ultra-low carbon nitrogen duplex stainless steel technology, the pump directly into a single volute, both to ensure corrosion resistance, abrasion resistance, and can withstand the pressure within the pump system And pipeline external force. Overcoming the complex structure of different materials used inside and outside the pump body. b. Reliable operation: Compared with rubber lined pump, the problem of linerless rubber shedding will not cause the blockage of the nozzle in the system, especially the spray tower, and increase the driving rate. In addition, a small aspect ratio, to improve the mechanical seal life; impeller and shaft double-bond connection, anti-reversing ability to further improve the reliability of pump operation. c. Long life: metal pump body operating life up to 50,000 hours or more. d. small maintenance: long life naturally means a small amount of maintenance, in particular the replacement of the pump lining need to be carried out, the removal of the export pipeline, but also a time-consuming maintenance work. Third, domestic-made metal slurry circulation pump industrial operation assessment. According to the above research and development results, Xiangfan May 25 Pump Co., Ltd. and China Hualian Group Hangzhou Banshan Power Generation Co., Ltd., to create a metal slurry circulation pump. The pump flow 4800m3 / h, lift 20.6m. On July 15, 2004 installed in Mid-Levels Power Co., Ltd. desulfurization Island on the 3rd circulating pump station. Through the actual operation, the pump hydraulic properties meet the technical requirements, stable and normal mechanical properties. From the operation of three months after the maintenance situation, the pump body, impeller, fender and other parts as bright as new machining traces clearly visible, indicating corrosion resistance and wear resistance to meet the requirements. So far, it has been up to 4000 hours. Fourth, the conclusion. Xiangfan 555 Pump Co., Ltd. developed a metal slurry circulation pump, half-Power Plant in Huadian Group Co., Ltd. 2X125MW machine (1 sets of desulfurization Island) successfully replaced the import pump, and has been operating for more than 4000 hours to prove that the metal-type slurry circulation Pump can be made locally. The trial pump selection of materials on the pump with ultra-low carbon nitrogen duplex stainless steel, impeller and front and rear shield selection of high chromium corrosion resistant wear-resistant alloy, the full application of dual-phase flow pump technology for hydraulic design and structural design; shows the metal Type slurry circulation pump long life, reliable operation, simple structure, a small amount of maintenance of the unique advantages. As the sole introduction of the domestic anti-corrosion and corrosion-resistant pump technology military enterprises, Xiangfan May 25 Pump Co., Ltd. from corrosion-resistant wear-resistant alloy casting, pump factory inspection of a series of casting, machining and complete testing equipment to Production flow from 1500 ~ 12000m3 / h, lift from 16 ~ 30m, suitable for 50MW to 600MW unit wet desulfurization equipment of various metal slurry circulation pump. The successful localization of the metal slurry circulation pump to the customer more than one choice, it is bound to our country flue gas desulphurization of key equipment have a certain role in promoting.
July 31, 2023
