Heilongjiang textile bookmark0 compressed air process selection Li Yujie (Heilongjiang Light Industry Design Institute, Harbin 150040, Heilongjiang) level requirements. It is economical and applicable to properly configure the processing equipment for compressed air. The air is compressible, easy to transport, and inexhaustible on the ground. In the industry, compressed air is widely used, and it has many good properties and features that are easy to adopt. All industries have different requirements for the quality of compressed air. Reasonable allocation of compressed air treatment equipment can save equipment investment and operating costs on the premise of meeting industrial production requirements. 1 The quality requirements of compressed air In the scope of food engineering, the quality requirements of the production process for compressed air mainly include the following categories: First, biological fermentation engineering. Such as: amino acid fermentation, vitamin fermentation and other aerobic fermentation, the production of pressure dew point 2 air dryer selection commonly used air drying equipment mainly frozen dryer, adsorption dryer, freeze-adsorption composite dryer, each Dryers have their own characteristics. The refrigerating dryer is composed of a refrigeration compressor, a condenser, an evaporator, a heat exchanger, a gas-liquid separator, etc., and the principle is to reduce the moisture content of the air by reducing the temperature of the air to cause condensation of moisture in the air. The pressure dew point of the refrigerated dryer is usually 2C according to the set value of the evaporator. Although the dehydration dryer has a much higher pressure dew point than the adsorption dryer, its operating cost is 1/31/5 of the adsorption dryer. Therefore, in the case where the pressure dew point requirement is not high, a refrigerating dryer should be used, except for outdoor long-distance pipeline transportation conditions in cold regions. Adsorption dryers usually use a double column type, one column for adsorption and the other for desorption. According to the regeneration method, it is divided into a non-thermal regenerative dryer, a micro-thermal regenerative dryer, and a thermal regenerative dryer. The actual working process of the non-thermal regenerative dryer is divided into three types: adsorption, pressure equalization and regeneration: 2011-03-25 Heilongjiang textile stage, micro-heating and hot regenerative dryers are divided into adsorption, regeneration, blowing cooling and pressure equalization. The stage constitutes a loop. During operation, the compressed air alternately flows through two tower containers filled with adsorbent. When one tower is adsorbed under working pressure, the other tower is desorbed near atmospheric pressure or heated state, and the two towers alternately switch. The main factors affecting the operation of the adsorption dryer are the intake air temperature and the working pressure. Generally speaking, the compressed air entering the dryer is saturated or supersaturated humid air. Under the same pressure condition, for every 50C increase in temperature, the saturated water content increases by about 30%, that is, the water load entering the dryer increases by about 30%; The adsorption capacity of the agent decreases with increasing temperature, so as the inlet temperature increases, the drying efficiency of the dryer decreases. The reduction of the working pressure will also cause the drying efficiency of the dryer to decrease, because the working pressure is reduced, the amount of regeneration gas is reduced, and the drying efficiency of the dryer is lowered. In addition, the pressure is lowered, and the flow velocity of the adsorption tower is also increased, resulting in an increase in the flow rate of the adsorption tower. The dynamic adsorption flow rate decreases, and these factors inevitably reduce the adsorption capacity, causing the dew point of the adsorber to increase. The performance ratings and scope of application for the three types of adsorption dryers vary. The non-thermal regenerative dryer has a minimum working pressure of 4 bar, a regeneration gas consumption of 20% 25%, a drying gas pressure dew point of -40 C, and an economical processing capacity of 3 m3/min 20 m3/min. The advantage is that the structure is simple and the equipment investment is small, but the regeneration gas The consumption is large and the switching is frequent; the minimum working pressure of the micro-heat regenerative dryer is 1 bar, the regeneration gas consumption is 10% 15%, the drying gas pressure dew point is -40C-60C, and the economic processing capacity is 10m3/min200m3/min. Advantages of thermal regeneration and thermal regeneration, comprehensive economic and technical indicators are good; thermal regenerative dryer minimum working pressure Ibar, regeneration gas consumption 5% 8%, dry gas pressure dew point -40C -80 °C, economic processing capacity 10m3/min200m3/min, which has the advantages of less regeneration gas consumption, long working cycle and low operating cost, but its structure is complicated and the equipment has high investment at one time; the freeze-adsorption composite dryer is to exhaust the heat-free regenerative dryer. The advantage of low pressure dew point is combined with the advantages of non-regeneration gas loss in the refrigerated dryer, which makes the dryer have low dew point and low energy consumption. The dew point below -700C and the regeneration gas volume are 5%. The composite dryer has low operating cost and good compressed air quality, and is suitable for high intake air temperature, but the structure is complicated and the equipment cost is high. 3 Air filtration After drying the air also needs to be filtered. Different grades of filters are configured according to different requirements of the user on the dust content of the air source. It is generally required that compressed air containing a particle size of 1 Mm and an oil content of 1 ppm only need to be equipped with a degreasing filter and a primary filter. In general, oil-free lubricating air compressors and screw air compressors still have a certain amount of lubricating oil in the exhaust gas, usually 5mg/m315mg/m3. If so much lubricating oil enters the adsorption type The desiccant will cause poisoning of the adsorbent. Therefore, before the inlet of the adsorption dryer, a degreasing filter should be provided, which can greatly extend the service life of the adsorbent. The primary filter element type is stainless steel fiber sintered felt, and the particle size of the filter is 0.3m, which is called the separation efficiency of 98%. Compressed air used in bio-fermentation engineering requires high air volume, low pressure, and air sterility, while bacteria have particles ranging from 0.25 m to tens of pm, and virus particles are in the range of 0.1 pm 0.01 pm, so the compression of supply On the basis of the primary filtration, the air also needs to be finely filtered to remove the particles, which are called m or more, and further sterile filtration to remove particles above 0.01 pm. In addition to ensuring sterility, compressed air used for milk powder delivery requires activated carbon filtration to remove odors to ensure product quality. In short, in the actual application of production, according to the different requirements of the user for the quality of compressed air, according to the selected air compressor, the appropriate air dryer and air filter are configured to achieve economical and reasonable. Shantui bulldozers are often used in road building, construction, mining, forestry, land clearing, infrastructure development, and any other projects requiring highly mobile, powerful, and stable earth-moving equipment. Shantui hydraulic drive series bulldozer features high technologic content, advanced and reasonable design, strong power, high productivity, and easy maintenances and repairs and can adapt to severe working conditions. 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Compressed air process selection