The status of dust control technology in cement plant
Date：2019-08-22 15:03 Source：cementepcViews:
In to deal with the dust while cement plant, must give priority to in order to prevent, reduce auxiliary prevention concept, so the first thing to deal effectively with dust pollution sources, to adopt advanced technology to prevent and reduce, and then, from the perspective of the communication process, strengthen the seal and leak of process equipment, effectively control the spread of the dust in the air, lowered its negative influence to the minimum.
1. Overview of cement production process of vertical kiln
Normally in the process of cement production, cement plant is through the rotary kiln and the shaft kiln cement production in two ways, rotary kiln, as the name implies, its essence is the use of the horizontal cylinder rotary type cement clinker calcining equipment in cement production, and the shaft kiln is the use of a static vertical cylinder type cement clinker calcining equipment production, shaft kiln production mode, the mode of the cement production process is raw meal preparation, will involve the raw material crushing operations, the matching of the raw materials, raw meal grinding, advance homogenization of raw materials and homogenization, etc.
2. Dust source and control analysis of cement dust
2.1 problems of cement production in vertical kilns
Cement kiln is the core part of the production of cement, at the same time the whole vertical kiln dust emissions from, directly affects its concentration is in line with international standards, it is not difficult to find in the investigation of practice, in shaft kiln dust in flue gas humidity, concentration, temperature fluctuation is very big, but also with a lot of corrosive gas, general temperature can reach 50 to 250 degrees Celsius, dew point in between 40 and 45 degrees Celsius, so the need to solve in shaft kiln dust under a lot of difficulties.
2.2 grinding system
The grinding process is used in the preparation of raw materials and the manufacture of cement, so attention should be paid to it.Yield and fineness of grinding, ventilation rate and matching between gas flow rate, affect the amount of dust produced, in addition, if the workers error, or poor sealing problems in the process of conveying, dust will be part of the leak, the dust concentration of the tail gas is in commonly 50 to 150 g/Nm3, severe situation can reach more than 200 g/Nm3.In the process of selecting a mill, it is better to choose a continuous mill to run in the material.If the kiln factory has the condition, can change the open circuit mill to the closed circuit mill, as far as the newly built kiln factory chooses the closed circuit mill.
2.3 dust problem in dryer
Dryer is one of the main places of shaft kiln cement plant dust sources, such as in the production of cement with coal powder, clay, and the slag material, drying process need to constantly follow bowl movement, at the same time continuously, also on some of the fine particles as the dryers hot waste gas spilling general dust concentration in the 50 to 150 g/m range, if there is no good dust collecting efficiency, so it is possible that there was more than standard of dust emission concentration more than one hundred times, the impact on the surrounding environment is very big.
3. Dust control technology analysis of cement plant
3.1 comprehensive dust control of vertical kiln
However, in recent years, in the development of closed-door operation, microcomputer control, and the use of pre-added water pelletizing technology, the dust concentration of shaft kiln exhaust gas has been greatly reduced, on this basis, continue to strengthen management, complete dust removal in the near future can be solved.In shaft kiln dust generated by the general way of settling chamber is used for collecting design, in the operation of the secondary dust removal, can choose to use a high voltage electrostatic dust removal, technical analysis of the dust removal effect was achieved 99%, but in the beginning stage of investment cost is very large, and management also requires a lot of money, so there is no certain popularity, you can also use the impact - spray dust in the form of joint dust removal effect can reach 96%, it not only has simple structure, does not need too much investment and beginning.
3.2 dust treatment in the grinding process
Generally when emissions from cement and raw meal grinding process, the original dust has a very high concentration, so mostly use the secondary dust removal device, the dust removal effect can reach 99% in practice, if the use level of dust removal, cyclone dust collector is the most commonly used tools, dust removal effect can reach 85% to 90%, but in use process must be sealed deduster discharging mouth operation, it will largely influence the effect of the dust collecting.In practice, rotary kiln sealing and discharging device should be timely maintained and replaced in daily use.Bag dust collection is a secondary dust collection characteristics, in the process of operation must pay attention to reduce the tension of the bag, so as to improve the service life of the bag dust collector, on the other hand can also improve the efficiency of dust collection.
3.3 dust treatment during drying
In the actual production and use, the dryer exhaust water in the range of 10% to 20%, has a high moisture content, but also has a high dust concentration, exhaust gas temperature in the range of 110 to 150 degrees Celsius, leakage point reached 50 to 70 degrees Celsius.Combined with these parameters, generally is the use of anti condensation bag dust collector, or the electric dust collector, dust collecting efficiency of the whole could be as high as 99.95%, but in the process of drying, the temperature of the material and water have very big fluctuations, in addition, the dryer exhaust dust than the resistance value of amplitude changed a lot, to a certain extent, it is easy to affect the efficiency of electrostatic precipitators, also affect the reliability of the work.To solve these problems, avoid too much dust caused environmental pollution, affect the staff's health, so to use wide spacing electric way to deal with the dryer flue gas to meet the requirements of dust removal technology, as the name suggests, is to increase the distance between the poles, improve the working voltage, to a certain extent, processing is greater than resistance, high concentration of dust.
3.4 dust treatment in packaging
The guarantee and loading and unloading of cement are the main places where dust is produced, and the operation process is easy to lead to secondary pollution due to technical limitations, and the dust concentration during packaging is between 20 and 30g/m. As these are finished cement products with high value, it is suggested that bag dust collector or electrostatic precipitator be used to purify the dusty gas.Screw set up the rotary conveyor to the packaging hoist, effectively solve the problem of scattered, broken package cement recycling.
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