Discussion on the Selection of Recycling Liquor in Vacuum Salt Making Industry Liu Yucong% Department of Mechanical and Electrical Engineering, Sichuan University of Technology, Zigong, Sichuan 643000, China) Performance, comparison of its advantages and disadvantages for the selection of circulating pumps.
Foreword Circulation pump is a very critical equipment in the external heating vacuum salt making process. It bears the task of conveying brine to the evaporation chamber. It has a large conveying flow, large power consumption, and its structure is good or bad and its performance is excellent. It will affect The energy consumption of the entire salt production line, the production cycle, and the quality of the products produced. If the circulation pump is not properly selected, it will also cause serious reduction of the subsequent equipment's working efficiency, such as blockage of the heating pipe and serious fouling.
The poor sealing performance not only increases the amount of brine loss, but also worsens the workshop environment, causing serious drop and leakage. So the requirements for the circulatory pump %1) meet the process performance. High efficiency; %2) Stable working conditions; %3) Due to the strong corrosive nature of the brine, good corrosion resistance is required; %4) Structural design is easy to disassemble, and maintenance is convenient; %5) Sealing performance is good. Less environmental pollution. In light of the above reasons, vacuum salt manufacturing companies should conduct extensive investigations when selecting circulating pumps, carefully screen them, and decide according to the specific conditions of the plant. At present, due to different production scales, various manufacturers use different sources of brine, and there are many types of circulating pumps used. Based on the 870-type circulating pump, a comparison analysis is made on the use of several commonly-used circulating pumps for equipment selection. Time.
The 870 circulator is one of the earliest circulating pumps used. It was a product developed by the Zigong Light Industry Design Institute in the late 1960s. It was used before the 1990s. At that time, the annual output of the vacuum salt industry was not high. The pump can basically meet the requirements, and the price is cheap, but it is bulky, the noise is large, there are also many problems in use, such as the performance is unstable, the anti-corrosion ability is poor, the style is cumbersome, the energy consumption is great, especially the maintenance cycle is short, the maintenance Large volume and high maintenance costs. Due to the corrosion of brine, the life of the impeller is short, and the impeller is generally replaced in the first half of the year. Some manufacturers must change the impeller once every 100 days, which often results in production suspension, which results in a series of problems such as low yield and poor efficiency. If the installation is not good or the gap adjustment is not in place, it will cause excessive vibration of the bearing parts, there will be serious wear of the ferrules and vibration in the bearing parts. The initial impact and vibration will be carried out in a very small range, and with the extension of working hours, The impact and vibration are aggravated. In severe cases, the shaft may be damaged, the round nut may come loose, the roller of the bearing may be broken, the seal yaw may be too large, the service life of the graphite ring may be reduced, and normal production may be affected. This can be mitigated by reducing the shaft and bearing intervals and ensuring the accuracy of the impeller blade angle. The 870 type pump is the earliest circulating pump used in the vacuum salt industry. However, with the development of the industry economy, especially the large increase in annual production, the 870 pump has gradually been replaced by other products, but due to its early use, it is still A few manufacturers continue to use it.
Liu Yulei: Discussion on the Selection of Circulation Pumps in Vacuum Salt Making Industry WFZ-700 Circulation Pumps As mentioned before, with the development of the domestic salt manufacturing industry and the expansion of production scale, the 0870 circulator can no longer meet the requirements. In the early 1990s, a new generation of circulating pump WFZ-700 pump was jointly developed by several units such as the Zigong Light Industry Design Institute. The practice indicated that this kind of pump has been used in place of the 0870 type circulating pump and has been working steadily since the pump has been boiling. In good condition, the plugging of the heating chamber and fouling conditions are much better than those of the 0870 pump. With the 0870 pump, the heating tube is susceptible to fouling and the heat transfer efficiency is low. After 3-6 months of operation, the mechanical operation must be performed. Descaling, while the WFZ-700 pump flow and efficiency are higher than the 0870 pump, due to the increase in the flow rate within the tube, the impact of heating the pipe wall, so that the formation of the dirt layer is not easy to improve the heat transfer efficiency, the use of high-performance salt and brine corrosion pump casing corrosion The impeller is made of E2 steel and has good corrosion resistance. Compared with the 0870, the small size, light weight, the use of mechanical seals, better sealing performance, easy removal, easy maintenance, due to short maintenance time, extended equipment operating cycle and reduce costs. Therefore, I believe that WFZ-700 pump is a good alternative to the 0870 pump. Sichuan is used more often.
(L series circulating pump (L series circulating pump) is a new circulation pump developed by Hubei Yinguang Huayan Machinery Manufacturing Co., Ltd. that digests and absorbs Swiss Sulzer Company's technology and combines with the technological conditions of China's salt industry, and is suitable for large flow and low lift. The particle-containing process environment is very suitable for the forced circulation of the salt making and nitrification industry.Compared with the 0870 circulating pump, the pump has a lighter weight and a smaller volume.As the 4L800 type in the series, the weight is only 0870 circulating pump 1 Only 1/3 of its volume is made of 316L ultra-low-carbon stainless steel, and the wear-resistance, corrosion resistance and salt-halo corrosion resistance are good. The cantilevered structure and suspended installation solve the thermal expansion stress compensation. The problem is that neither the equipment nor the expansion compensating section is needed, and the connection between the pulley and the shaft adopts a new type of taper sleeve structure, which is easy to disassemble, and the large belt pulley can be adjusted axially, and can be easily disassembled and adjusted when installing or repairing. Pulleys: The bearing box has enlarged oil storage space, and the total amount of oil is 15kg, which can guarantee no replacement of lubricating oil for one year.The box body adopts integral casting with good strength and beautiful appearance. The seal of the pump adopts the sealing structure of PTFE-graphite packing with double layers of packing, using two kinds of sealing water, fresh water from sealing and cooling, the brine acts as an isolation, effectively preventing fresh water from entering the brine layer and avoiding diluting the medium, so as to avoid Evaporation efficiency is affected, replacement of packing is convenient, and it is not necessary to eliminate the mother liquor in the tank. Currently, there are more pumps of this type in Hubei salt industry, but the installation requirements of this pump are high, and if it is not installed well, its use performance will be greatly reduced. In order to meet different needs, 4L series pumps also have different models, their flow rates, Yang Cheng and other technical parameters are different, such as 4L800-2 main technical parameters: flow 132kW. If you need more flow, you can choose (L900 type Circulation pump There are more than one manufacturers who produce this type of pump, and the technical parameters are slightly different, which can be adjusted within a certain range according to the use conditions.
Pump, (L900 circulating pump is suspension test structure, pump body flange and circulation pipe flange docking, the pump body suspended in the circulation tube, automatically compensates for the thermal stress due to thermal expansion and contraction. With the same (L800 pump, small size , Lightweight, easy to dismantle, wear and corrosion resistance, smooth operation, use imported bearings, a set of radial cylindrical roller bearings and two sets of radial thrust bearings, can withstand large radial loads and shafts at the same time The load is easy to adjust and the clearance is good.The power is 160kW, and the efficiency is also high.The pump uses a triple combination seal, the cost is low, but the leakage is larger than the mechanical seal. In addition, due to the overall structure, replace the impeller, shaft and other parts The entire pump needs to be removed, so maintenance is not very convenient.
5 Concluding remarks At present, in order to reduce costs and increase market share, the vacuum salt industry is becoming large-scale and diversified product development. To achieve this, the choice of equipment is a key issue, for the selection of circulating pumps. Because the brine components used by various manufacturers are different, the production capacity is not the same, the technological process is different, and the relevant equipment is not the same. It should also be analyzed in combination with its own specific conditions, and it cannot be generalized so that the circulating pump can be properly selected.
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