Application and Discussion of Coal Optimized Control System
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I. Equipment and Control Principles
1.1 Equipment principle: TCS-200A is the universal control equipment of the ball mill, which is used to control the amount of material and the amount of ball during the operation of the ball mill. The amount of material refers to the percentage of the volume of the material and the internal volume of the ball mill, that is, the material filling rate of the ball mill. The function of the control system includes two parts of material level measurement and automatic feeding control. The material level measurement is realized by detecting the audio signal of the ball mill. The automatic feeding control is achieved by controlling the material level at a fixed value. By controlling the material level at a fixed value, the change of the power (or current) of the ball mill motor reflects the change of the ball filling rate. Therefore, by maintaining the power (or current) of the ball mill motor at a certain value, it can also be Realize the constant value control of steel balls. 
1.2 Automatic control principle: Based on the PID adjustment and control output protection, according to different given values, to achieve automatic control, the main control methods are the following: fixed value, tracking, maximum, economic mode; "fixed value" Refers to controlling the material level in the coal mill to stabilize at a fixed value. "Tracking" means that in the manual mode, the control system tracks the actual operating parameters. "Maximum" refers to the maximum output search method. "Economy" refers to the way of economic optimization. Our factory adopts a "valued" control method. Its control principle is shown in Figure 1. 
2.1 First, the emptying and full tank calibration of the coal mill and the PID parameters of the controller are corrected. Refer to Table 1 for the specific calibration. 
2.2 Determined that the amount of coal stored in the pulverizer barrel reached 20%. By increasing the amount of coal delivered to the coal feeder and reducing the amount of ventilation of the system, the high level operation of the pulverized coal airport was achieved, and coal input was automatically performed. 
Due to the reduction of ball load of the pulverizer, the grinding current is reduced by about 10A (from 72A to 62A) and the current running current is reduced to 62A. Through the analysis of the test results of the pulverized coal fineness (R90), the coarse powder is separated twice. The baffle angle of the device is about 40 degrees from the original to about 50 degrees, and the pulverized coal fineness is kept within the specified requirements. 
The output of the milling system basically remains the same as the original operation mode. In the actual operation process, through the changes of the load of the unit and the powder level of the silo, a single set of pulverizing system can basically carry 90,000 loads. Through the analysis of statistical data, it is also the same as the actual results. (Introducing power through electricity consumption and milling unit consumption indicators.)
2.3 During the debugging process, sometimes the system air pressure fluctuates greatly and the system cannot be put into automatic operation. According to the analysis, due to the large amount of air ventilation in the system, the back of the system is large, and the concentration of pulverized coal increases, which increases the load of the coarse powder separator, and therefore causes the system air pressure to fluctuate. By reducing the ventilation volume of the pulverizing system (gradually pushing the discharge baffle from full opening to 60% opening), the system air pressure is stable, but the output is significantly reduced, and the drying output is affected. 
2.4 After a comparative analysis, the original air volume of the system was maintained and the material level was adjusted down to 15%. 
Third, pay attention to
3.1 The normal operation of the milling system and the optimization device shall be operated in accordance with the parameters required by the operating card. The running card parameters are shown in Table 2 parameters.  
3.3 adjust the coal mill inlet hot air door to maintain the mill outlet temperature within the required range, while adjusting the recirculation door to maintain the mill inlet negative pressure stability. The outlet air temperature of the mill should be maintained at the upper limit of 80°C as much as possible and not lower than 65°C. Otherwise, the output will be reduced and the pulverizing system will be unstable. 
3.4 The coal feeder's automatic input in the whole process: no matter whether the coal mill is in running state, as long as the manual coal feeding is adjusted to 50% opening degree, and then the automatic switch is combined, the coal can be automatically adjusted automatically. Under normal circumstances, the coal mill only needs to stop the coal feeder in the process of shutdown, and it is not necessary to release the automatic coal feeder; only the coal feeder needs to be started during the start-up process, and no automatic decommissioning operation is required. 
3.5 When the material level indicator exceeds the upper limit of 40%, the automatic adjustment of the coal supply is maintained at the lower limit opening degree of 10%. At this time, no automatic solution casting operation is required. Automatic adjustment range for coal feeding: the upper limit opening is 70%, the lower limit opening is 10%, and the equivalent opening of the material level 20% is about 40%. After the coal is automatically and stably operated (corresponding to 2% material level), the boiler operating personnel shall pay attention to monitoring the outlet temperature of the coal mill, the inlet negative pressure, and the pressure difference at the inlet and outlet. 
3.6 Because the pressure difference at the inlet and outlet of the mill is proportional to the square of the air volume and related to the factors such as the accumulation of powder on the mill outlet and coal quality, the pressure difference is the reference for the coal storage capacity and ventilation conditions of the coal mill. During the operation, avoid using the coal mill inlet cold air door to adjust the air temperature of the milling system. According to the condition of powdered ground, it is necessary to start and stop the operation of the coal mill in time, and prohibit the low level of the coal mill or the idle operation of the coal mill. 
Fourth, there is a problem
4.1 The coal quality changes too much, leading to unstable operation of the system: more fine powder in the raw coal, dry coal, and increased milling output, leading to higher system air pressure; raw material in the raw coal, coal temperature, milling output decreased, leading to Insufficient drying power. Therefore, when the coal quality is poor and the change is large, it is recommended that the operator manually control it. 4.2 Coal feeder coal seam thickness variation: When the coal seam thickness is high, the coal input is automatic, the coal feed current is maintained at about 17A, and the system is working normally; when the coal seam thickness is thin, the coal supply current is maintained at a maximum of about 23A. Can not add up, can not be put into coal automatically. 
4.3 A large coal mill operating current fluctuations (more than a dozen amps), can not accurately monitor the ball load. A, A grinding inlet negative pressure indication: Sometimes negative pressure reaches -200Pa normal (hand test); sometimes -500Pa about coal feeder inlet hot air. 
V. Summary
By adding the TCS-200A ball mill level monitoring device, it has a positive interest in the economic and optimal operation of the coal control system, greatly reducing the labor intensity of the operating personnel. At the same time, through the operation and debugging of the equipment, we added a certain protection logic in the DCS configuration. That is, when the steel mill differential pressure is greater than 3000Pa or the coarse dust separator outlet negative pressure is less than -6500Pa, the controller will automatically The output is locked at 30%. Once normal, the controller re-enters the automatic adjustment state. However, this protection is prone to system fluctuations when the coal quality changes greatly, resulting in coal plugging. Therefore, it is recommended that manual control be adopted in this case.
Nickel-based laser cladding powders typically consist of nickel as the main component, along with other alloying elements such as chromium, molybdenum, and tungsten. These alloying elements help to improve the mechanical properties, corrosion resistance, and wear resistance of the resulting coating.
Nickel-based laser cladding powders are commonly used in various industries, including aerospace, automotive, and oil and gas. They are often chosen for their excellent corrosion resistance, high-temperature strength, and ability to withstand harsh environments.
The laser cladding process using nickel-based powders can be used to repair damaged or worn-out parts, enhance the surface properties of components, or create new parts with specific properties. The laser beam melts the powder material, which is then rapidly solidified to form a dense and metallurgically bonded coating.
Overall, nickel-based laser cladding powders offer a versatile and effective solution for improving the performance and lifespan of components in various industries.