Ball mill coarse powder. Fine powder pumping machine iron making plant coal injection workshop milling system with traditional steel ball mill, secondary fan, three-stage dust collection system. The operation process pipeline is long, and the powder collection system is from the fine powder separator, the multi-tube separator to the bag filter, the control valve is large, the system resistance loss is large, and the multi-tube separator is a positive pressure zone in the production process, and the coal often appears. Poor, blockage and other failures affect normal production, and the control is difficult; the use of secondary air mechanism powder has the disadvantages of tons of coal power consumption and high hot air temperature, consumption of blast furnace gas children. Therefore, simplifying the process and eliminating the secondary fan is a beneficial attempt.
No. 13 ball mill mechanism powder process transformation of raw coal through the grinding machine grinding and burning furnace hot air drying, coal powder and hot air through the coarse powder separator, fine powder separator and powder discharge machine, multi-tube separator, bag filter ,ventilator. The exhaust gas is discharged into the atmosphere through the cigarette, and the pulverized coal enters the pulverized coal bin through the three-stage dust collection system. See the process flow.
Raw coal, flue gas bag chimney before the transformation of the No. 3 ball mill mechanism powder process 1.2 Simplified process flow reasons and broadcast 2.1 Reasons for simplifying the process In the normal production process, due to the existence of recirculation pipes, hot air will be on this pipeline Produce "short circuit". If the ball mill is clogged, the result will be the fire of the bag. On the process line, there are the powder inlet and outlet butterfly valves, the circulating air valve, the bag separator, and the population butterfly valve. The system pressure loss is caused by many valves during operation. The working condition is difficult to adjust; the multi-tube separator is a positive pressure zone, which often causes faults such as poor coal and blockage, which affects the normal powder collecting function; the inlet butterfly valve of the powder discharging machine is only 50% open, and the powder discharging machine is idle. Power. These factors constrain the increase in the output of the ball mill.
1.2.2 Simplified process flow modification The recycling pipe, multi-tube separator and exhaust fan were eliminated, and the butterfly valve of the original powder discharge machine, the bag filter, the population butterfly valve and the circulating air butterfly valve were eliminated. The population of the machine is moved from the outlet of the fine powder separator to the outlet of the bag filter, and the outlet of the fine powder separator is connected with the population of the bag filter to make the whole system in full negative pressure; only the powder eliminator and powder discharging of 220 kW are reserved. Machine inlet butterfly valve, the purpose of retaining the inlet butterfly valve of the powder discharge machine is to adjust the system air volume. The process flow is simplified to: ball mill, coarse powder separator, fine powder separator, bag filter, fan. See the process flow.
1.3 Equipment modification and signal display Four star-type ash discharge valves are installed in the lower part of the bag filter, and the screw conveyor is modified, and the original Ls25 is modified into Ls315 to speed up the ash conveying speed of the bag filter and avoid the process transformation. The post-bag dust collector has more coal accumulation, which produces the phenomenon of spontaneous combustion of coal powder and keeps the production conditions normal.
In addition, on the instrument display screen, the display signals of the working state of the ball mill, star-type ash discharge valve, screw conveyor, fan and coal belt equipment are added to provide convenient operation.
2 After the transformation, the operation practice was reformed one month. At the beginning of May, the single-wind mechanism powder system of the ball mill No. 3 began to be debugged. The commissioning was divided into two stages: empty load and trial production with load. Based on the principle that the inlet and outlet pressure differences of the ball mill before and after the transformation are roughly equal, the air load is debugged, and the relationship between the butterfly valve opening value, the pressure difference of each online device, and the operating current value of the fan is obtained. Carrying out the trial production with load, the trial production is based on the principle of the maximum capacity of the ball mill qualified coal powder, strictly control the temperature value of the inlet and outlet parts of the bag filter, and increase the inlet and outlet pressure of the bag filter by 7.85 - by increasing the cleaning frequency. In the range of 11.77 kPa, the trial production process with load is relatively smooth. From the pressure loss of the whole system, the pressure loss of the system before the transformation is 105.91 kPa; the pressure loss after the transformation is only 83.36 kPa, and the hot air temperature required to meet the production of the ball mill inlet is reduced from the original 370-400 to 250-290T. The required blast furnace gas consumption is only 2/3 of the blast furnace gas consumption before the reform. The system pressure loss and the furnace gas consumption are significantly reduced, and the purpose of the transformation is achieved. It is not difficult to see that the energy consumption of the system will be reduced with the reduction of the resistance after the transformation; because the butterfly valve used to adjust the system process parameters is only one, it also makes the milling operation relatively easy.
2.1 Milling operation and analysis after transformation 2.1.1 The powder making operation after the transformation confirms that the equipment is in good condition, closes the fan inlet butterfly valve, starts the dust removal equipment and the fan, and adjusts the valve position of the fan inlet butterfly valve after the fan is running normally. Inform the burner furnace for 50, start the ball mill when the temperature of the furnace reaches 650; notify the furnace to supply air, open the hot air valve, and close the cold air valve. When the outlet temperature of the ball mill gradually rises to about 80T, the vibrating feeder is started to supply coal to the ball mill, and the coal supply amount is adjusted from small to large to adjust the outlet temperature of the ball mill (in general, the outlet temperature of bituminous coal or lignite is controlled at 50~) 60, the export temperature of anthracite is controlled in the range of 70-85). During the operation, it should be adjusted according to the principle of maintaining the maximum output of the ball mill, and ensure that the moisture content is <1.% and the fineness of the coal powder. 0088mm accounts for 65%-90% of qualified coal powder. 2.1.2 Operational analysis In the production process, the main production data of the milling operation are shown in Table 1. Table 1 Main production data of the milling operation Pressure eight Pa current / A opening /% coarse powder bag cloth bag fan ball mill M mouth From the inlet and outlet entrance exit population butterfly valve, it can be seen from Table 1 that the ball mill current is basically the same as before the transformation, the fan current is reduced by 2A before the transformation, indicating that the production status at that time is normal, and the produced qualified coal powder accounts for 82%; Adjust the valve position of the fan population butterfly valve to 70%. The main production data at that time is shown in Table 2. Table 2 The main production data after the valve position adjustment Pressure / kPa current / A opening / coarse powder bag cloth bag fan inlet inlet The inlet and outlet inlet inlet valves can be seen from the comparison between Table 2 and Table 1: the fan current drops by 2A, that is, the current difference between before and after the transformation is 4A. This data change indicates that the resistance loss of the system after the transformation is reduced. The power consumption of the entire system has been significantly reduced. At that time, the production data and the pressure at each test point fluctuated within the normal range and stabilized in the range shown in Table 2. It shows that the running-in of the system is better and the production reaches the normal state.
The whole process took more than a week, and the output of the ball mill reached more than 19 tons (the nameplate output of the No. 3 ball mill was 16t/h), and the qualified coal powder (particle size of 200 mesh) remained at around 73% for a long time.
2.2 Analysis of transformation effect After simplifying the process flow, the system pipeline is shortened, including eliminating the multi-tube separator, reducing the control valve, reducing the resistance of the milling system, reducing the power consumption of the system, and increasing the ventilation of the system to 46,500 m3/h. The earth exerts the production capacity of the ball mill, and the output of the ball mill is more than 19 tons. The single-fan production process is simplified after the transformation. The operation of the butterfly valve can be adjusted to achieve the purpose of adjusting the system air volume and production conditions. There are many valves before the transformation, and it is difficult to adjust.
After canceling the secondary fan, not only a fan with a power of 55 kW was reduced, but also the current of the fan produced online was reduced by 4 A compared with the current of the fan when the secondary fan was produced. The single-fan production process achieved power saving, Reduce the power consumption per ton of coal. Table 3 shows the statistics of electricity consumption per ton of coal from January to November 2002. Before the single-fan was put into operation, the electricity consumption per ton of coal was basically around 50kWh. In May, the single-fan started production, and the power consumption began to decrease. As of November, the average power consumption dropped to 45.lkWh. The annual production cost was 200,000 yuan. In addition to the economic value of the saved blast furnace gas, it is expected that the investment cost of the transformation will be recovered during the year.
Since the whole system is full-press negative powder, the leakage of coal powder is reduced, the labor of the employees is reduced, and the environment at the production site is improved, which is beneficial to the physical and mental health of the employees.
In the month, the ventilation of the whole system of the single fan production reached 46 500m3/h, and the chimney wind speed reached 25m/s, which was doubled compared with the pre-reform air volume of 26000m3/h and the wind speed of 12.7m/s. As the air volume increases, the relative pressure of each part of the system also increases synchronously, so that the original bag mouth seal can not withstand such a large pressure. After four months of production, the bag mouth seals were successively damaged (mainly because of the small area of ​​the dust bag), which led to the bag dust removal box body, which affected the milling production and the dust emission concentration exceeded the standard. Later, after treatment, a channel steel bead was added to the bag mouth to press the bag mouth seal, and a good effect was obtained.
3 Conclusion Meishan No. 3 ball mill single fan technology transformation after the production is stable, the ball mill can produce more than 19t, which plays the ball mill's production capacity.
The production of single-fans has reduced the electricity consumption per ton of coal and the effect is obvious. If the condition of the bag filter is expanded when the single fan is modified, the effect will be more obvious.
(Editor: Zhao Ling) (Continued from page 21) After the coal, the Y value decreased slightly, the coke strength also decreased, and the wear resistance increased slightly. Scheme 3 Although the fat coal uses 15% of Xinjia coal and 10% of Shanxiao coal, the proportion of gas coal is reduced, the proportion of coking coal is increased, the Y value is 15, the cohesiveness is still moderate, and the coke quality is also good.
5 Conclusion Through the small coke oven test and large production practice, it can be seen that in the current coal structure, replacing 10%~15% of Zaozhuang coal with 10%~15% Xinshi coal can not only reduce the sulfur content of coke. And the quality of coke can also be improved. After field investigation, Xinji coal is rich in resources, coal quality is stable, and transportation is guaranteed. It can be used as one of Meishan coking coal bases.
(Editor: Zhao Ling)
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