Compressed air is the second largest power energy after electricity, but also has a variety of uses in the process of gas source, its applications throughout the petroleum, chemical, metallurgy, electric power, machinery, light industry, textiles, automobile manufacturing, electronics, food, medicine, biochemistry, national defense, scientific research and other industries and sectors. Undesirable is the compressed air contains a considerable number of impurities, mainly: solid particles - in a typical big city environment per cubic meter of the atmosphere contains about 140 million particles, of which about 80% in the size of less than 2 μm, the air compressor suction filters are incapable of eliminating. In addition, the air compressor system will continue to produce internal abrasive debris, rust residue and oil carbide, they will accelerate the wear and tear of the air equipment, resulting in seal failure; water - the relative humidity in the atmosphere is generally as high as 65% or more, the compression of condensation, that is, it has become wet saturated air, and entrained with a large number of liquid droplets of water, which is the root cause of corrosion of the equipment, piping and valves, and icing in the winter will also block the pneumatic system in the Small holes in the pneumatic system. It is worth noting that: even if it is separated from the net of pure saturated air, with the lowering of the temperature, there will still be condensate precipitation, about every 10 ° C, its saturated water content will fall by 50%, that is, half of the water vapor into liquid water droplets (see Table 1). So in the compressed air system using multi-stage separation and filtration devices or compressed air pretreatment into a certain relative humidity in the dry air is very necessary; oil - high-speed, high-temperature operation of the compressor using lubricants can play a role in lubrication, sealing and cooling, but contaminated compressed air. The use of self-lubricating materials to develop less oil machine, semi-oil-free machine and oil-free machine although the compressed air to reduce the oil content, but also with the consequent reduction in the life of wearing parts, machine internal and piping system corrosion and air compressors in the break-in period, wear and tear and load reduction period of the rise in oil content and other side effects. This is undoubtedly a threat to the pursuit of high reliability of automated production lines. It should also be emphasized that the oil brought into the system from the compressor is not beneficial under any circumstances. Because after many high-temperature oxidation and condensation emulsification, the performance of the oil has been greatly reduced, and acidic, the subsequent equipment not only can not play a role in lubrication, but also undermine the normal lubrication; micro-organisms - in the pharmaceutical, bio-engineering, food manufacturing and packaging processes, the contamination of bacteria and phage is not to be ignored.
Table 1
Temperature (℃)
80
70
60
50
40
30
20
10
Water vapor content (g/m3)
292.9
197.9
130.1
83.2
51.2
30.4
17.3
9.4
Temperature (℃)
0
-10
-20
-30
- 40
-50
-60
-70
Water vapor content (g/m3)
4.8
2.2
0.9
0.34
0.12
0.035
0.011
0.0028
In summary, if the pollutants in compressed air are not effectively removed, the harm is great, mainly in: First, reduce the quality of the main product (affecting the processing accuracy, spraying, plating quality, pharmaceuticals, food dyeing bacteria, etc.); Second, causing the performance of the air equipment, the decline in the life of the third, the harm of the purification system (eg, the oil reduces the performance of the adsorbent to reduce the heat exchanging efficiency of the cooler, etc.), in addition to the oil can reduce the performance of the adsorbent to reduce the heat exchange efficiency of the cooler, and so on. (such as oil can reduce the adsorbent performance, reduce the heat exchange efficiency of the cold dryer, etc.), in addition, due to the failure of pneumatic components caused by downtime, maintenance and other indirect losses, the cost of which is often for the direct loss of hundreds, thousands of times.
With the progress of science and technology and the development of industrial modernization, especially the rise of high-tech industries, compressed air (gas) pollution and its purification technology has attracted the attention of the gas sector and manufacturers. With oil, water, dust, in addition to the odor of a variety of purification devices continue to be developed, the market demand is increasing day by day. The development of compressed air purification technology is not only for the emerging high-tech industries and traditional industrial transformation to provide clean, reliable air source, but also from the development of high-tech benefit.
2. foreign compressed air purification technology development
a) new ideas, new technologies - to open up the way to get oil-free compressed air after treatment and purification of new ideas, the development of a high-efficiency, low-resistance type of oil filter, not only become a strong competitor of the oil-free lubrication compressor, but also to promote a variety of oil-sprayed compressor (screw, worm-rotor, rotor, etc.) development, the technology The technology is built on the basis of new microfiber filter material and cohesive filtration mechanism.
b) Diversification of water removal methods and equipment - coalescing high-efficiency filters can be almost 100% separation of liquid droplets to obtain the working temperature of the pure saturated air; refrigeration dryer can be obtained from the pressure dew point of 2-10 ℃ of the drier air; adsorption dryer and even reach the dew point of the pressure of the -70 ℃ of the following super-dry air.
c) ultra-filtration device development speed is extremely fast - when the traditional filtration methods are still maintained in a few microns to tens of microns filtration accuracy, the use of microfiber, hollow fiber, membrane and other new materials, high-efficiency, ultra-high-efficiency filter filtration accuracy indicators in one fell swoop to the sub-micron level in order to obtain high-performance oil or microbial removal effect, the commercial performance of a number of foreign brand-name products have reached the target of 0.01 micron, filtration efficiency up to 99.9999% or more.
d) purification of air applications are increasingly expanding, the quality of the indicators 赿 to 赿 high - according to information on the Japanese market demand for compressed air purification devices almost every five years will be turned over; Germany ultrafilter ultrafiltration company in just five years on the development of international multinational corporations, the United Kingdom Domnick company into the nineties has become a combination of gas, water purification of cross-specialty companies, filter cartridges have been developed from the gas, water purification of the Cross-specialty companies, cartridges have developed from cartridge to folding; purification of gas not only become a necessary production conditions of many high-tech industrial sectors, but also popularized to such as mining, civil construction, shoemaking, brick-making and general workshop gas such as a number of traditional industries. The quality level is 1 to 3 levels higher than for the same domestic applications (see annex). The quality indicators are required not only at the end of the gas supply system, but also in the purification system.
e) The corresponding standards and test methods are becoming more and more perfect, as can be seen from the six drafts of ISO8573.
3. Domestic air purification technology and equipment status
Domestic compressed air purification technology and product performance and popularity compared with foreign countries, lagging behind 10 to 20 years. Foreign
Sixties adsorption dryer development is mature; in the mid to late seventies, high-efficiency filters have made significant progress; in the eighties, the popularization of refrigerated dryer, ultra-filtration technology development is noteworthy. Domestic imitation adsorption dryer from the end of the seventies; the end of the eighties began to imitate high-efficiency filters; refrigeration dryer in recent years has just begun to take off. Comparison of domestic and foreign purification product performance and popularity is shown in Table 2.
Table 2
Products
Foreign
Domestic
Adsorption desiccant dryer
Pressure dew point of -20～-70℃, divided into two categories of heat and non-heat regeneration, which can satisfy the needs of users of all grades
Pressure dew point of -20℃, only able to meet the medium and low-grade users.
Refrigerated dryer
Pressure dew point up to 2 ~ 10 ℃, has been popularized
Pressure dew point of 2 ~ 10 ℃, the introduction of the assembly is mainly, the development of faster
Degreasing filters
Purification gas oil content of 0.01 ~ 1 mg / m3, has been popularized
Estimated oil content 1 ~10 mg/m3, (no standard test bench)
Sterilization filter
For 0.01μm particles, the efficiency is as high as 99.9999% or more, is being popularized and applied
Being tried out
Adsorption filters
Residual oil content of 0.003 mg/m3, has been popularized
Still blank
The development of domestic compressed air purification devices mostly started from mapping imitation, technology and market development and the introduction of the scale of
growth of synchronization. Into the nineties, the pace of independent development and technology introduction accelerated. At present, the domestic compressed air purification products compared with similar foreign products, varieties and quality there is a gap, some varieties are still blank. But the appearance of these products to meet part of the market demand, and at the same time to improve the domestic air purification awareness has played an obvious role in promoting.
4. cohesive high-efficiency filter mechanism and structure
Due to the presence of water vapor in the atmosphere and the air compressor working process of lubricant pollution, the removal of compressed air in the oil and water pollution has become the focus of the purification of the post-processing and difficult. Although almost all compressed air in the application of one or several levels of separation, filtration devices, but due to the condensation effect produces a huge number of suspended oil-water aerosol particles (for example, the particle size of the oil is about 0.01 ~ 0.8 μm), and the traditional separation, filtration equipment on its inability to do anything about it or the efficiency of the very low (see Table 3).