1.02. It is suggested that the fineness of the
pulverized coal should be controlled below 6% and the moisture content should be controlled below 3%. Special attention should be paid to the internal water content of the pulverized coal, which seriously affects the combustion calorific value of the pulverized coal. Pay attention to the dilution of pulverized coal, reduce the dust content in the coal mill air, and ensure that the dilution range of the calorific value of the finished pulverized coal and the calorific value of the converted raw coal entering the plant is within 100-150 kcal, the lower the better.
03
As for the fineness of the raw meal, it is recommended that the 0.08 mm sieve residue should be controlled below 20%, but it must be ensured that the 0.2 mm sieve residue is not high. If the 0.2 mm sieve residue cannot be guaranteed, it must be reduced by
0.04.
As for the burnability of the raw meal, At present, it is suggested that the proportion of medium saturation ratio and high silicon ratio (this depends on the plant, and the actual difference is large), the free calcium of clinker should be controlled below 1.5%, even below 1.8%, and not less than
0.05 chemical additives should be
used. At present, coal-saving additives include coal-saving additives added to coal and raw grinding AIDS added to raw grinding system. At present, the technology is becoming more and more mature, and with the rise of coal price, the cost-effective advantage of chemical additives is more obvious. It is suggested that we find high-quality additives manufacturers for trial, and we can sign a contract energy management mode to control risks. There is basically no loss for cement enterprises.
06
Reduce the outlet temperature of C1 and improve the separation efficiency of C1 outlet, and the gas out of the preheater and the returned ash will take away a lot of heat. According to the calculation in some literature, when the outlet temperature of the preheater is reduced by 10 degrees, the standard coal consumption will be saved by about 0. We should pay attention to the measurement of the amount of returned ash, and the heat taken away by the returned ash is not small. It also affects the subsequent processes such as the power consumption and abrasion of the high temperature fan. It is suggested that the separation efficiency of the C1 cyclone should be increased to more than 92%, preferably about 95%, and the dust concentration of the outlet flue gas should be reduced to less than 80g, preferably 50-60g.
07
Control the concentration of carbon monoxide and oxygen in the flue gas at the outlet of the preheater. The discharged carbon monoxide is the coal consumption. The increase of oxygen content indicates that the system has too much air leakage or too much air, which increases the energy consumption; The gas analyzer here should be calibrated and maintained well. It is recommended that the gas analyzer here can measure four components: oxygen content, carbon monoxide content, nitrogen oxide content and sulfur dioxide content. These four parameters are very important for operation.
08
Pay attention to the pulverized coal combustion of the decomposition furnace. The phenomenon of after-combustion of pulverized coal and upside-down of C5 temperature shall not occur. The combustion of pulverized coal in the calciner and the mixing of air, coal and material shall be understood. The position of C4 material entering the calciner, the dispersion of raw material powder and the mixing of pulverized coal and raw material powder shall be studied; The better the mixing of pulverized coal, raw meal powder and tertiary air is, the more complete the combustion is, and the lower the coal consumption is. At the same time, the local high temperature is reduced, the generation of nitrogen oxides is also reduced, and the amount of ammonia injection is reduced. Here, the maintenance and replacement of the ammonia spray gun are also focused on to ensure that the ammonia can be uniformly dispersed in the flue gas at the temperature of the reaction window period, so as to improve the reaction efficiency, reduce the amount of ammonia and reduce the amount of ammonia escape.
09
The control of kiln inlet temperature is not easy to be too high, which indicates that too much coal is used at the kiln inlet, and it is easy to increase the risk of skinning in the smoke chamber. At present, the popular design scheme of large smoke chamber with feed chute can be considered to reduce the amount of secondary dust of raw meal powder from the five-stage cylinder and the amount of skinning in the smoke chamber.
As for the sectional area of the kiln end necking and the moon door (the junction of the kiln and the smoke chamber), we should dare to try to expand it. As long as the material does not collapse, it will not have a great impact on the calcination and process. The bigger the better. It can be tried bit by bit. Now the kiln is shut down for many times. When the kiln is shut down, the pneumatic pick is used to remove part of the castable for experiment. After finding out the appropriate size, the castable is redesigned and poured again.
11
Kiln head burner also has great influence on coal saving. At present, there are many burner manufacturers, and the current mainstream design is to reduce the primary air volume, increase the primary air pressure, and reduce the production of nitrogen oxides; the burner should be explored and debugged, combined with the ingredients, to find out the parameter values suitable for their own working conditions.
12
Pay attention to the secondary air temperature of grate cooler. The secondary air temperature should not be lower than 1100 ℃. If the secondary air temperature is high, the tertiary air temperature will also rise, which can save a lot of coal consumption. At the same time, the clinker quenching is also beneficial to the clinker grindability and clinker strength. It is recommended to use the fourth-generation grate cooler with mid-set roller crusher process. If the old factory can not do it, it can ensure that the fan current of the first three chambers is at a high level to strengthen the clinker quenching. If necessary, replace the fans in the first few rooms. During the construction of castable, special attention shall be paid to the protection of the grate plate to prevent the castable slurry from blocking the grate gap, and the grate gap shall be cleaned regularly.
13
Pay attention to the internal and external heat preservation of the firing system. For the refractory bricks in the kiln, it is suggested to use energy-saving refractory bricks such as composite thermal insulation bricks, thermal insulation module bricks and low thermal conductivity refractory bricks to reduce the surface temperature of the cylinder as much as possible. According to the literature, the rotary kiln cylinder has the largest surface heat dissipation. For the kiln hood, tertiary air duct, grate cooler, kiln tail smoke chamber and other parts, it is absolutely not allowed to directly pour castables without using thermal insulation materials. For the top of the kiln hood, it is recommended to use the current popular energy-saving hanging brick, in which a layer of thermal insulation castables is poured, and the service life can reach three to five years; New thermal insulation materials such as nano thermal insulation and aerogel thermal insulation can be used in the tertiary air duct, preheater and other parts to reduce the surface temperature of the outer shell and increase the furnace capacity. In the northern cold areas, it can be considered to make external thermal insulation for the C1 cyclone as a whole to reduce the surface heat dissipation. Enterprises with good internal and external thermal insulation can reduce the standard coal consumption of about 3kg only in terms of heat dissipation.
14
Pay attention to the stability of the pulverized coal scale and the kiln raw material scale. In case of large fluctuation, corresponding inspection, maintenance or replacement must be carried out, because the large fluctuation of the scale measurement will inevitably cause large fluctuation of the process quality. In order to stabilize the thermal condition and stabilize the quality, conservative operation is adopted during the operation. Resulting in an increase in coal consumption.
15
Intelligent operation technology such as expert system is adopted. At present, the intelligent operation technology has been mature, and the price has been greatly reduced. The quality of cement industry equipment and the number of parameters entering DCS operation basically meet the requirements of intelligent operation. Some old production lines need to add hardware to meet the requirements. However, intelligent expert operation can greatly reduce the labor and errors of manual operation, make the adjustment more accurate and the operation more refined. After use, most enterprises can reduce the coal consumption by 1-3kg, and some enterprises even more.
Through the implementation of the above measures, it is believed that the standard coal consumption of most cement enterprises can reach the secondary energy consumption standard of 107 kg/ton clinker or lower, plus the use of alternative fuels, high calorific value hazardous waste and other measures, some enterprises can reach the 94 kg level better than primary energy consumption standard.
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