The air jet looms are analyzed and studied with the characteristics, quality, pressure and flow of compressed air. The basic requirements of compressed air in air jets for moisture, oil content, dust and carbon powder, as well as air compressor lubrication and cooling methods are proposed. Selection, basic principles of air compressor selection, etc., and the calculation method of gas supply volume and gas supply pressure are given. It is considered that the air compressor should be reasonably calculated according to the number of air jet looms and gas characteristics. Air volume and supply pressure, and choose the cooling method of air compressor according to local climatic conditions and water resources conditions. From the perspective of energy, energy consumption and investment, the paper analyzes and studies the selection of air compressors and the quality of compressed air. In recent years, with the development of the textile industry towards high-end apparel fabrics, various new air jet looms have been introduced and used, and the demand for compressors has also increased. Since most textile companies do not understand the aerodynamic characteristics of air jet looms, compressed air consumption, air pressure pipe network characteristics, external operating conditions on the performance of air compressors (hereinafter referred to as air compressors) and energy consumption, in air compressors When selecting the model, a simple method of selecting the model according to the consumption amount is adopted, which results in the abnormal operation state of the air compressor, and can not exert its proper performance. The equipment has large investment at one time, high energy consumption, and economic benefits are not obvious. In this paper, the characteristics of compressed air consumption in the production of air-jet looms in the textile industry, under the condition of meeting the production requirements of air-jet looms, the aerodynamic characteristics and gas parameters of the air-jet looms are determined. Consumption is different from other gas equipment. In order to better determine the gas consumption and working pressure of the air jet loom, the gas utilization mechanism of the air jet loom must be analyzed. 11 Air jet loom aerodynamic characteristics Air jet loom normally performs weft insertion requiring constant pressure of compressed air. Due to the high latitude of the air jet loom, the speed of the loom has exceeded 3000m/min, and the number of weft insertions per unit time (600 1200 times/mn) is lighter, so the amount of compressed air consumed per weft insertion Less than 000007m times ~00012m Huan) The machine arranged in the air jet loom workshop is similar to the air consumption of the air jet loom as a relatively stable value. The more machines in the workshop and the higher the speed of the loom, the smaller the pressure and flow change of the compressed air in the workshop per unit time. 2 The air consumption of the air-jet air-jet loom for weft insertion in the air jet loom varies depending on the type of the loom, the type of fabric, and the speed of the loom. In general, the technical parameters such as the predetermined fabric fiber type, yarn number, warp and weft density, and loom speed should be provided to the supplier, which can be calculated and determined by the supplier, or according to the parameters of Table 1 The 190m loom woven cotton fabric is taken as an example). Table 1 Different number of yarns, various looms, air consumption, yarn count, range of compressed air consumption, m3 Note: A indicates that the speed of the loom is 500r/mB, indicating that the speed of the loom is 700r/minC. The speed of 900r/mn 3 working pressure is determined by the working pressure of the air jet loom. It is related to the fabric specifications, fiber type, loom width, loom speed and loom performance. The data should be provided by the weaving machine supplier. The fluctuation should be less than 0 01MPa and can also be initially determined according to Table 2. Table 2 Common Loom Working Pressure 2 Compressed Air Quality Requirements and Air Compressor Selection Analysis In order to ensure good operation of the air jet loom, the quality of the compressed air is essential to ensure the weft insertion error, ensure the fabric quality, and compress the moisture in the air. The oil content and cleanliness should be controlled within a certain range. The compressed air quality of air jet loom should meet the 1S8573- 1 compressed air quality standard. The moisture content allows the pressure dew point of the compressed air to be set below 10 °C and meets Class 4 requirements for moisture content classification. Below 1mgm, the level 2 requirement classified by oil content is reached. Dust and carbon powder above 3Mm meet the Class 2 requirements classified by dust content. 1 Air compressor lubrication method Currently, the air compressors supplied on the market are oil-free and oil-oil. The oil-free machine uses an oil-free lubricating screw to achieve pressure rise. The machine has no oil in the compression chamber, and the sealing and lubrication between the screws are sealed and lubricated by spraying self-lubricating material and tetrafluoroethylene film. The main advantage of this machine is that the output air can be completely oil-free. However, due to the characteristics of the screw itself, the single-stage compression ratio is limited (usually using two-stage compression). The exhaust pressure is generally less than 0. 75MPa compression causes the rotor to wear and the coating to peel off due to water vapor and other factors, resulting in a seal gap. Increasing, the compressor efficiency is reduced, and this type of machine is expensive. The oil machine uses the 24KT lubricating oil which is free of change in the compression chamber, so as to cool, seal and lubricate, so that the compression ratio is increased (the first-stage compression ratio can reach 20-30), and the compression efficiency is improved. Single-stage compression, the exhaust pressure can be higher than Q75MPa, the air discharged by the high-efficiency oil separation device, and can be used by the precision oil separation device. The price of the machine is low, but the consumption of 24KT lubricating oil is large, coupled with the high cost of wearing parts such as primary and secondary oil separator filter elements, resulting in high operation and maintenance costs. In view of the above situation, when selecting the lubrication method of the air compressor, the economic and technical comparison should be selected according to the comprehensive situation of the enterprise. Generally, oil-free air compressors should be used for filaments and fine high-density fabrics; oil-based air compressors can be used for short-fiber and medium-thick fabrics, but precision filtration devices are needed to enhance the removal of oil in compressed air. Comparison of single performance of air compressors with different lubrication methods: type oil-injected screw-type oil-free screw air compressor air compressor 10% oil-free. It can be seen from above that although oil-free air compressors have a one-time investment The air compressor is high, but the comprehensive operation cost is low and the economic benefits are obvious. 22 cooling method analysis Air compressors commonly used cooling methods are air-cooled and water-cooled. Since the water cooling adopts the evaporative cooling method, the cooling water below the air temperature can generally be obtained, and the specific heat and density of the water are large, and the cooling effect on the air compressor is good, so it is generally more used. However, the water cooler needs to be equipped with a cooling tower and a cooling water pump. The system is complicated to operate, and the cooling water is easy to scale, which affects the heat transfer effect. The air-cooling machine is simple in equipment and low in maintenance cost. However, for large air compressors and hot areas in the south, the high outdoor air temperature will cause the cylinder temperature of the air compressor to be high and stop. Therefore, when using the air cooler, ensure the distance between the machines and the ventilation and cooling of the equipment room, so that the temperature of the equipment room is lower than 40 ° C. Therefore, when selecting the cooling mode of the air compressor, it should be based on the local meteorological conditions and the water quality of the cooling water source. Analytical determination. The cooling method of the general air compressor can be selected according to Table 3. Table 3 Air compressor cooling mode under different exhaust volume selection Area cooling mode Moderate area Air-cooled water-cooled Summer hot winter warm area Wind-cooled water-cooled Summer hot and cold winter area air-cooled air-cooled. Water-cooled, water-cooled, cold, cold, wind-cooled, cold-stricken areas, air-cooled Note: A means that the air compressor discharge is less than or equal to 3m3/mnB, indicating that the air compressor discharge is 4 beats / -20! / (;: indicates that the air compressor exhaust volume is greater than or equal to 20m3 / mn 23 common air compressor working principle analysis is currently used more screw air compressor and centrifugal air compressor. Compared with the two, the main advantages of the screw machine are: first, uniform intake and exhaust, no pressure pulsation, stable operation of the machine, no need to set the gas storage tank, small foundation or even no base rotation; second, the oil injection screw can Obtain a higher single-stage pressure ratio and a lower exhaust gas temperature; thirdly, it has the characteristics of forced gas transmission, that is, the exhaust gas volume is hardly affected by the exhaust pressure, and the internal pressure ratio is basically independent of the rotational speed and density. It is especially suitable for parallel operation of multiple machines; Fourthly, when the working point changes within a large range, the machine efficiency does not change much, and there is no surge phenomenon when the centrifugal air compressor has a small displacement. The disadvantage is high noise, the total sound pressure machine can reach 104dB (A) must adopt noise reduction and noise reduction measures; the exhaust volume is smaller than the centrifuge. The main advantages of the centrifugal air compressor are as follows: First, the structure is tight, the second is pure, oil-free operation, the compressed air is not polluted by lubricating oil, and the quality is high; second, the efficiency is high and energy is saved. The disadvantages are as follows: First, it is easy to generate surge phenomenon during the start and stop process, and vibration is generated; secondly, the change of the displacement amount has a great influence on the mechanical efficiency. Under a certain speed, there is an optimum working condition point, which deviates from the The efficiency of the point will decrease; secondly, the left side of the performance curve of the compressor is limited by the surge condition Qun and the right side is restricted by the blocked working condition. The area between the two is the stable working area of ​​the centrifugal compressor; Multiple units are operated in parallel. When the single unit exhaust volume and exhaust pressure can meet the requirements, less machine should be used for gas supply. In view of the fact that the air flow rate of the air jet looms of the textile mill is stable and the pressure P is not high (0. MPa), it is necessary to select the air compressor according to the specific conditions at the time of production. Centrifugal compressors should be used in places where the number of weaving machines is large, the compressed air consumption is large, the gas pressure is low, and the gas consumption is stable; the gas pressure is high (PQ7MPa and the flow rate is greatly changed and multiple machines are needed) When paralleling, it is advisable to use a screw air compressor, or a centrifugal compressor and a screw compressor to work in parallel, and the screw air compressor is used for flow regulation. 3 Air supply capacity and air supply pressure of the air compressor station After the air compressor cooling mode and lubrication mode are determined, it is of great benefit to save energy by correctly determining the air supply pressure and air supply volume of the air compressor. The air supply pressure of the air compressor is reduced by 0 MPa, which can save 5% of energy consumption. 1 Determination of gas supply The air supply capacity of the air compressor station for air jet loom should be calculated as follows: Q=Q(1+K)N(1) The amount of compressed air consumed by the loom (m/min) K is the piping system. The leakage rate (generally 02 ~ 04) N is the number of air jet looms. 32 Gas supply pressure determination Reasonable determination of the air supply pressure of the air compressor is essential to ensure the working efficiency of the air jet loom, save energy and prolong the service life of the air compressor. The air supply pressure of the air compressor can be calculated as follows: the light weight of the single machine 〖qi large" like 0 reachable (3)000: "toe disc and other resistance loss (MP) generally take / value 105MPabookmark3 4 conclusion should be based on the air jet loom The number and gas characteristics of the air compressor are selected. For systems with large gas consumption, single type, stable operation, and high quality of compressed air, centrifugal air compressors should be used to save energy. For small-volume, multi-variety air-jet looms, systems with large changes in gas load should use screw-type air compressors with good parallel characteristics. The air consumption and air pressure of the air jet loom should be reasonably calculated, and the number of air compressors should be correctly selected to make the air compressor operate in a higher load and high performance area, which is essential for energy conservation. The cooling method of the air compressor should be selected according to local climatic conditions and water resources conditions to reduce energy consumption and improve the operating efficiency of the compressor. (4) By properly determining the system pressure and flow, and correctly selecting the air compressor type and cooling mode, the energy consumption of the entire air compressor system can be greatly reduced, and the energy saving effect is obvious. Ridge Cap Roll Forming Machine Ridge Cap,Metal Roof Making Mahcine,Metal Roll Forming Mahcine Botou Hongyuan Forming Machine Co.,Ltd , https://www.tilemakingmachinery.com
Performance Analysis of Compressed Air for Air Jet Looms