First, the program description At present fertilizer plant has a total of four pressurized fans, of which two sets of large fan power is 280KW, the other two sets of fan power were 240KW, 155KW, under normal circumstances is a 280KW and 240KW work (current is 490A, 405A) Use the main circuit valve opening to adjust the air flow to meet the needs of the rear compression section. This results in the need to manually adjust the loop valve to stabilize the system pressure when the system load changes, and a part of the power is consumed on the loop valve for a long period of time.
This system can be based on the specific needs of a drag two, one drag three ways, one drag and three methods are more secure compared to the control is also more flexible, can still be in the two motor problems Guarantee the normal operation of the frequency conversion control system and minimize the risk of the system. If one considers that the cost and system security can meet the requirements, a one-to-two control scheme can also be used.
In the selection of inverters, because the blower fan is a very important part of the entire production line, and the Roots blower is a heavy load compared to the centrifugal blower, the inverter requires higher when the starting torque and load change, so we are In this solution, a general-purpose inverter is used, and the general-purpose inverter in the IGBT inverter module, rectifier element, and energy storage element is more than a fan-water pump-type inverter of the same power and is used to amplify a file, which can more effectively ensure the frequency converter. Stability, reliability and service life.
According to the status quo of the process, the frequency conversion control system adopts a closed-loop control method, the circuit valve is fully closed, the outlet air pressure is collected by a pressure sensor to the inverter, and the voltage and frequency parameters output to the motor are adjusted through the PID loop adjustment of the inverter, thereby adjusting the motor. The speed of rotation in order to achieve the purpose of constant wind pressure at the outlet. In this way, the system pressure can be automatically stabilized when the system load changes, and the power consumed in the circuit valve can also be effectively saved.
Second, the control circuit 1, can easily start and stop the inverter in the operating room and speed adjustment;
2. Uninterrupted switching from variable frequency to industrial frequency can be achieved to meet the system's need for safety;
3. When the 280KW variable frequency motor or 240KW power frequency motor fails, the frequency converter switches to another 280KW motor, and the original 280KW or 240KW motor frequency operation avoids the influence of frequency conversion closed loop control due to frequency conversion motor failure. .
4. When the frequency converter or the motor fails, sound and light alarm can be used to facilitate timely troubleshooting;
5, the pressure target value can be specified at any time according to the needs of the process, the operation is simple and convenient.
6. The input current and voltage of the inverter and the device can be observed in real time in the operation room to facilitate the understanding of the working condition of the motor and the device.
Third, benefit analysis 1, energy-saving effect is obvious. According to the load characteristics of the fan, the power is proportional to the third power of the fan speed. When the speed is decreased, the motor power drops rapidly. Generally, the fan's average power saving rate is more than 20%. At present, the Shanghai Huzhou Tianli Chemical Fertilizer Plant pressurizes the work at 380V×(490+405)A×0.89÷1000×24 hours×30 days×1.732=217936 degrees per month. The opening of the circuit valve is approximately 1/3, and the energy conservation is conservatively estimated. 20%, then save electricity 43587 degrees per month, according to the average price of electricity 0.35, you can save 1,5255.00 yuan per month, according to the work of 10 months a year calculation, the annual savings of 15,2550.00 yuan.
2. Increased the stability of process parameters, reduced the consumption of materials, and can effectively increase production efficiency and reduce unit costs.
3, through the inverter to adjust the fan speed (motor starting from 0Hz), the motor can be soft-start, to achieve constant pressure air supply, can reduce the starting current, improve the quality of electrical protection, thereby increasing the starting torque, therefore, on the motor and the grid The impact is reduced, the starting pressure drop is reduced, the capacity requirement of the power grid is reduced, the frequency converter can quickly detect and protect, and its protection function is complete. The response speed and accuracy of protection are greatly improved compared with conventional electrical protection, and the protection of the motor is greatly improved. More perfect, it is conducive to the safe operation of the motor.
4. It solves the phenomenon of rolling pressure when the outlet pressure rises, reduces mechanical wear, reduces equipment losses, and reduces mechanical wear of motors, fans, etc., which can effectively extend the service life of the equipment and reduce equipment maintenance and procurement costs.
5. The control method is closed-loop automatic control, which improves the degree of automation in production and eliminates the error in manual adjustment. Fast response, high precision, and easy control: The mechanical properties of the inverter are hard, the speed regulation performance is good, it can meet the strict process requirements, and the control quality is high.
This system can be based on the specific needs of a drag two, one drag three ways, one drag and three methods are more secure compared to the control is also more flexible, can still be in the two motor problems Guarantee the normal operation of the frequency conversion control system and minimize the risk of the system. If one considers that the cost and system security can meet the requirements, a one-to-two control scheme can also be used.
In the selection of inverters, because the blower fan is a very important part of the entire production line, and the Roots blower is a heavy load compared to the centrifugal blower, the inverter requires higher when the starting torque and load change, so we are In this solution, a general-purpose inverter is used, and the general-purpose inverter in the IGBT inverter module, rectifier element, and energy storage element is more than a fan-water pump-type inverter of the same power and is used to amplify a file, which can more effectively ensure the frequency converter. Stability, reliability and service life.
According to the status quo of the process, the frequency conversion control system adopts a closed-loop control method, the circuit valve is fully closed, the outlet air pressure is collected by a pressure sensor to the inverter, and the voltage and frequency parameters output to the motor are adjusted through the PID loop adjustment of the inverter, thereby adjusting the motor. The speed of rotation in order to achieve the purpose of constant wind pressure at the outlet. In this way, the system pressure can be automatically stabilized when the system load changes, and the power consumed in the circuit valve can also be effectively saved.
Second, the control circuit 1, can easily start and stop the inverter in the operating room and speed adjustment;
2. Uninterrupted switching from variable frequency to industrial frequency can be achieved to meet the system's need for safety;
3. When the 280KW variable frequency motor or 240KW power frequency motor fails, the frequency converter switches to another 280KW motor, and the original 280KW or 240KW motor frequency operation avoids the influence of frequency conversion closed loop control due to frequency conversion motor failure. .
4. When the frequency converter or the motor fails, sound and light alarm can be used to facilitate timely troubleshooting;
5, the pressure target value can be specified at any time according to the needs of the process, the operation is simple and convenient.
6. The input current and voltage of the inverter and the device can be observed in real time in the operation room to facilitate the understanding of the working condition of the motor and the device.
Third, benefit analysis 1, energy-saving effect is obvious. According to the load characteristics of the fan, the power is proportional to the third power of the fan speed. When the speed is decreased, the motor power drops rapidly. Generally, the fan's average power saving rate is more than 20%. At present, the Shanghai Huzhou Tianli Chemical Fertilizer Plant pressurizes the work at 380V×(490+405)A×0.89÷1000×24 hours×30 days×1.732=217936 degrees per month. The opening of the circuit valve is approximately 1/3, and the energy conservation is conservatively estimated. 20%, then save electricity 43587 degrees per month, according to the average price of electricity 0.35, you can save 1,5255.00 yuan per month, according to the work of 10 months a year calculation, the annual savings of 15,2550.00 yuan.
2. Increased the stability of process parameters, reduced the consumption of materials, and can effectively increase production efficiency and reduce unit costs.
3, through the inverter to adjust the fan speed (motor starting from 0Hz), the motor can be soft-start, to achieve constant pressure air supply, can reduce the starting current, improve the quality of electrical protection, thereby increasing the starting torque, therefore, on the motor and the grid The impact is reduced, the starting pressure drop is reduced, the capacity requirement of the power grid is reduced, the frequency converter can quickly detect and protect, and its protection function is complete. The response speed and accuracy of protection are greatly improved compared with conventional electrical protection, and the protection of the motor is greatly improved. More perfect, it is conducive to the safe operation of the motor.
4. It solves the phenomenon of rolling pressure when the outlet pressure rises, reduces mechanical wear, reduces equipment losses, and reduces mechanical wear of motors, fans, etc., which can effectively extend the service life of the equipment and reduce equipment maintenance and procurement costs.
5. The control method is closed-loop automatic control, which improves the degree of automation in production and eliminates the error in manual adjustment. Fast response, high precision, and easy control: The mechanical properties of the inverter are hard, the speed regulation performance is good, it can meet the strict process requirements, and the control quality is high.
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