According to the latest “Cement Industry Air Pollutant Emission Standards”, the cement kiln dust emission standards will be reduced from the original 50mg/Nm3 (cement kilns and other thermal equipment) and 30mg/Nm3 (concrete mills and other ventilation equipment) to 30mg/Nm3 and 20mg /Nm3.
Dust pollution has always been an unavoidable problem in the development of the cement industry. At present, dust removal methods used in the industry mainly include electrostatic precipitator and bag dust collector.
Based on different process characteristics, compared to the bag dust removal, the operation and maintenance costs of the electrostatic precipitator are lower, but the dust removal effect is slightly worse on the same scale. However, due to the large amount of dust in the cement industry, the efficiency of electrostatic precipitators is greatly affected by equipment performance, management level, and working conditions of the production line. Dust removal efficiency varies. Only a few cement companies in China can use electric dust to achieve national emission standards. Because of this, bag filters with relatively fewer constraints and higher dust removal efficiency have become the first choice for more cement companies to reduce their dust emissions.
However, the selection of a suitable filter bag is a major challenge for cement companies to face when choosing a bag type dust removal device. At present, there are many types of bag-type dust-removing materials in China. In the application of cement-reservoir dust collectors, they mainly include pure P84® filter bags, P84® composite filter bags, glass fiber-covered filter bags, domestic PI filter bags, and so on. Due to the different properties of the material itself, there are major differences in the filter effect and service life of the various filter media during use, especially pressure difference.
The merits of the filter bag material of the dust collector need to be comprehensively considered from the aspects of dust removal effect, service life, and operational energy consumption. At present, most of the filter media used by domestic companies can achieve better dust removal results in the initial stage of operation. However, as time goes on, the differences between different materials will undoubtedly be revealed.
According to reports, most of the filter fibers are round or nearly circular in cross-sectional shape, in the process of intercepting dust, can not prevent dust from infiltrating into the filter, resulting in blocking the gap of the filter material, after prolonged use, there are even Ash leakage risk. The resistance to the passage of smoke will gradually increase, and the operating pressure difference of the bag filter will increase, and the operating energy consumption will continue to increase. In general, the energy consumption of the induced draft fan occupies most of the operating cost of the enterprise bag filter, and even the cost of the ultrafilter bag.
Pure P84® filter media are used as examples. All P84® multi-leaf specialty fibers can achieve very good surface filtration. It is difficult for dust to enter the interior of the filter media. It can effectively prevent the air resistance caused by dust blocking the filter media from increasing. problem.
In terms of service life, pure P84® filter bags can generally reach 4 years or more in the application of kiln tails. We have hardly seen problems with the normal use of pure P84® filter bags in 4-5 years. There is even a cement kiln dust removal project using pure P84® filter bags, which has an operating life of 7 years and a pressure difference of only 100-200 Pa in 7 years.
From the dust removal effect and service life, P84® is undoubtedly one of the preferred filter materials for belt filter in cement companies, but at the same time, the material is also relatively expensive, which also makes many cement companies feel “tangled”. .
In fact, in order to reduce costs, domestic filter manufacturers have also made a lot of “exploration.” For example, the P84® composite felt filter material currently on the market is generally made of glass fibers mixed with P84® fibers, but the P84® content is not the same, from 10%, 15%, 18% to 20%. One by one. Although the P84® composite filter bag can meet the standard of early dust removal, with dust infiltrating into the deep layer of the filter media, dust can easily accumulate inside the filter media. After a certain period of use, the operating resistance is greatly increased and the dust removal operation cost is increased.
Speaking of the uneven production process and reputation of each filter bag manufacturer, the content of P84® fiber added to the P84® felt is difficult to guarantee. Therefore, it is difficult to judge the P84® composite felt material from practical use effects. In terms of effect, the P84® felt filter material is certainly far inferior to a pure P84® filter bag, and the low cost of its filter bag often cannot compensate for high costs during operation, such as shorter service life and higher energy consumption. Cost, not to mention the risk of stopping the kiln due to the need to replace filter bags. Lu Ming believes that from the perspective of comprehensive utilization and longevity, it is best for cement companies to use pure P84® filter media. Taking into account the current cost pressures in the cement industry, it is recommended to use pure P84® filter media at the kiln end, and in other dust collectors. P84® composite felts can be used.
For the glass fiber covered filter media widely discussed in the industry, under the ideal conditions of use, the glass fiber coated filter media can meet the emission requirements of cement companies. Performance indicators in all aspects can also be compared with pure P84® filter media.
However, compared with pure P84® filter media, glass fiber coated filter media are “precious” and require higher requirements for packaging, transportation, installation, equipment, and operation. In the above process, it is easy to cause coating materials. Damaged, adversely affect the dust removal effect. At present, the pressure drop of fiberglass coated media on the domestic market is generally high. On the other hand, due to the large profit margins, the development of domestic glass fiber covered film market is turbulent, the competition is disordered, quality and technology are uneven, and it is the instability of product quality that limits its development.
Therefore, the pure P84® filter bag is still the first choice for the dust removal in the cement industry. Even if the acquisition cost is relatively high, based on the longer service life and lower operating energy consumption, the overall cost is relatively low and the cost is low. Under the increasingly important industry background, it is worth thinking deeply in the cement industry.
