Process optimization and energy-saving design of compressed air system

Process optimization and energy-saving design of compressed air system Zheng Lei, Sun Honggang 2, Sun Cuicui 1 1. Yucheng Yangjin Textile Co., Ltd., Dezhou, Shandong 251200, China; 2. Luyin Investment Group, Jinan, Shandong 250001, China 3 different types of air compression mainframes The scope of screw air compressors has been widely used in many industries such as chemical industry, food, medicine, textile, etc. due to its superior performance and high efficiency. In addition, through further design of the overall air compressor station, the selection basis of equipment such as gas storage tanks, filters and cold dryers is further analyzed, and the energy-saving technical points that should be paid attention to in the design of the scheme are pointed out, and the process of compressed air is explained. The significance of the program and energy-saving design to reduce costs and increase efficiency.

The textile industry, which was once the first production factor and the pillar industry of the national economy, is gradually declining its industrial status. The main reasons are the intensified competition in the industry, the decline in the level of industrial profit margin, and the decline in the proportion of the national economy. . In recent years, the difficult pattern of China's textile enterprises in the market competition is obvious to all. In addition to the fierce competition factors such as India and Vietnam in emerging markets, there are also reasons such as rising costs of enterprises and the overall quality of personnel. Therefore, while focusing on market development and product innovation, textile enterprises need to always grasp the main line of reducing costs. Compressed air equipment is an auxiliary facility that most textile enterprises use. How to use this equipment most economically is not only a subtle manifestation of energy conservation and emission reduction, but also an initiative to reduce costs and increase efficiency, so optimize the compressed air supply process. It is also a concrete manifestation of cost control.

1 Air compressor selection At present, the air compressors we use mainly come in three forms: piston type, screw type, and centrifugal type. In general, the three types of air compression mainframes, hereinafter referred to as air compressors, each have their own advantages in equipment management, energy consumption control and other aspects.

point. Below we select the host from the performance, cost of use, etc. of the three types of hosts.

1.1 Comparison of performance and characteristics of different air compressors According to Table 1, we can see that the piston air compressor has the advantages of low price, high efficiency and firm structure, but it also has piston pulse exhaust, large maintenance, and compressed air is easy to contain oil. The shortcomings of water and low self-control level are generally applied in places with harsh environment and low compressed air quality requirements, such as mining environment; screw air compressor is continuous exhaust, although the flow regulation is limited, but the efficiency is high, at the same time Because the fuel is not driven, the quality of the compressed air is relatively high. Although the price is relatively expensive, the maintenance is less, and the later use cost is low. It is widely used in food, medicine, military, machinery, textile and other industries; centrifugal air compressors in all aspects The advantages are also obvious, but due to the small range of flow regulation and low efficiency, the application range is small, such as the inflation compressor used in store opening, wedding, etc.

1.2 Comparison of the use cost of different air compressors Because the centrifugal air compressor itself has insurmountable shortcomings, it is relatively less used in industrial systems. Below we mainly compare the use cost of piston and screw air compressors of the same power.

From Table 2 we can see that the same power of the screw, piston air compressor in the power consumption, the screw type is significantly better than the piston type of the 13 types of air compressor main features of the main features piston screw centrifugal exhaust form Pulse continuous continuous displacement is small Large flow adjustment range /%0~10040~10070~100 Structural form Small size requires solid and light noise/dB90(A)85(A (full cover 85 (A (full cover efficiency) High and low cost, low, high maintenance, small size, small self-control level, low and high, table 2, air compressor, cost of use, comparative analysis, category 22 kW, screw air compressor, 22 kW, piston air compressor, gas production index, low pressure, high pressure, 0.75 MPa, displacement (/ N3min-) 3.52.3 monthly average electricity consumption / degree 80,006,600 monthly average oil consumption / kg3.5 hydraulic oil 25.0 oil annual average maintenance cost / yuan 15005 000 total consumption equivalent / yuan 7000065000 electricity; but due to screw air compressor The failure is low, the maintenance cost is low, and the exhaust efficiency is about 1.5 times that of the piston air compressor, and the annual total consumption equivalent cost is only 1.08 times that of the piston air compressor, so compared with the comprehensive use of the screw air compressor The cost is lower.

1.3 Air compressor selection scheme Through the above analysis, screw air compressors are more reasonable choices, both in terms of performance and overall cost of air compressors. With this qualitative determination of the host, the next important task is to determine the number of hosts in the solution, which is our quantitative analysis, to design an optimal design. In order to maximize the production requirements, in order to achieve uninterrupted air supply to the air compressor, we must fully consider the air compressor downtime, maintenance and other related factors when designing the solution, so usually the number of hosts is determined. Configure the main unit at 12 units higher than the rated exhaust capacity to achieve alternate air supply or maintenance replacement between the main units.

2 Selection of other equipment 2.1 Selection of gas storage tank The capacity of the gas storage tank should be configured to take 30% of the total exhaust gas per minute of all air compressors. There is no strict regulation on the number of gas storage tanks. The corresponding number of gas storage tanks should be configured according to the actual gas supply requirements. In general, in order to ensure the stability of the gas supply pressure and facilitate the maintenance and use, we adhere to a principle in the configuration of the gas storage tank: while ensuring the capacity of the gas storage tank, the number of configurations is as small as possible, and the capacity of a single gas storage tank To be as big as possible.

2.2 Selection of cold dryer The cold dryer is the key equipment for de-oiling and removing water from compressed air. When selecting the dryer, the dew point temperature of the dryer should be determined first. 2. Select the treatment gas volume of the dryer on this basis. The calculation formula is as follows: the air flow to be treated, that is, the air compressor row. Cp is the intake pressure correction coefficient 1.00; Ct is the intake air temperature correction coefficient (1.6; Ct is the dew point temperature correction coefficient (1.0; Ct is the ambient temperature correction factor 1.29. 2.3 Other equipment selection except to select the above equipment In addition, we also need to choose the pre-filter and the post-filter. In order to ensure the processing capacity of the filter, the selected filter processing gas volume is about 150% of the air compressor, and the processing accuracy should be based on the gas quality required by the terminal. In the standard, it is necessary to configure several filters for the high quality of the gas source. In addition, the pipes of the appropriate diameter should be configured according to the required gas volume of different parts.

3 The overall scheme is designed in the design of small gas supply stations composed of 3 or more air compressor mainframes. According to different production gas requirements, we can generally use two schemes to connect them to the pipeline network: the species is the gas storage tank The series supply of gas; one is the parallel supply of gas to the gas storage tank.

3.1 The series gas supply scheme of the gas storage tank can be seen in series. After connecting all the small gas storage tanks in series, it is equivalent to the function of a large gas storage tank. This connection method is mainly applied to the centralized gas supply reform. This eliminates the need to purchase large gas storage tanks. However, it should be noted that the use of such a connection must meet the premise: there is no significant difference in the pressure and quality requirements of the compressed air.

3.2 Parallel gas supply scheme of the gas storage tank The difference between the parallel gas supply and the series gas supply is that the gas storage tanks are not connected to each other in the connection of the gas storage tank. In general, this type of connection is mostly used in applications where the quality of compressed air is significantly different.

Main post 1 - air compressor; 2 - gas storage tank; 3 - pre-filter; 4 one cold dryer; 5 - rear filter gas storage tank parallel gas supply scheme other energy-saving design attention points 1 host and storage On the connection of the gas tank, the gas storage tank should be placed as close as possible to the host. This is mainly because the closer the gas storage tank is to the main engine, the shorter the loading time of the main engine and the less energy is consumed when the compressed gas reaches the upper limit pressure under the same conditions.

2 In the process setting of the gas supply pressure, under the premise of meeting the basic supply pressure, the low pressure and high pressure should be set in the lowest range to save energy. However, it must be noted that the difference between low and high voltage needs to be greater than 0.15 MPa to avoid frequent start-up of the host and damage to the equipment.

3 The host should be placed in a well ventilated environment. In addition, we suggest that in the cooling of the main engine, the water cooling and cooling can be achieved without the need of air cooling and cooling, and the oil cooling and cooling can be achieved without water and cooling.

5 Conclusion Compressed air is not only an auxiliary gas used by textile companies, but also widely used in equipment pressurization and environmental cleaning in many industries. It can be said that this seems to be a very inconspicuous production necessity. However, on the other hand, it is precisely because of its extensiveness and universality that in the current situation of energy conservation and emission reduction, how to use the gas supply equipment system more economically is significant. Of course, in the current difficult situation of textile companies, even if we can save one kilowatt hour every day, it is the direction we should work hard.

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