In the chemical, metallurgical, mining, textile and other industries, a large number of roots fans, pumps, mixers and compressors are used. These machines are generally driven by AC motor, and the power is more than a few hundred, some as high as even thousands, and the power consumption is very considerable
Carefully observe the operating conditions of these machines, and you can find that most of them are not working above the rated power for a long time. Instead, they often only have an output of 50%-70% or even lower. However, most of these machines currently use constant speed AC drives. , Adjusting with baffles, valves or venting the return method will lose a lot of electricity in vain. The more powerful the Roots blower, the more serious the situation.
The large-scale frequency conversion device can smoothly adjust the motor speed by changing the voltage and frequency of the driving power supply, and change the output power according to the requirements of the output quantity, so as to save a lot of electric energy
How to directly control the air volume according to the working conditions to meet the requirements of the working conditions? The appearance of frequency converter solves this problem very well. The frequency converter is stepless speed regulation. The use of frequency converter to transform roots blower has the following characteristics:
1. Start stop balance, stepless speed regulation, wide speed range.
2. Reliable operation and long-term stable operation.
3. Easy operation and small maintenance.
4. The output characteristics can meet the performance requirements of Roots blower.
5. There is no impact on the power grid when the motor is started, and the mechanical wear is very small.
According to the characteristics of Roots blower, the flow change of Roots blower is directly proportional to the rotating speed, the pressure change is proportional to the rotating speed, and the power change is proportional to the cube of speed change. Therefore, when the speed of Roots blower decreases, the air volume decreases. The power of the motor decreases in square ratio. Through summarizing the application of frequency converter in Roots blower, it has the following advantages:
1. It has obvious effect of saving electricity and reducing consumption. It is easy to operate and adjust balance.
2. Smooth start and rotation speed decrease, mechanical wear and failure rate decrease, which reduces the impact of shutdown on production.
3. The mechanical wear and seizure of the baffle and control valve no longer exist.
In view of the current situation of 280KW pressurized roots blower in nitrogenous fertilizer plant, since the pressure required in the subsequent desulfurization and compression section fluctuates little in the stage time, we adopt the multi-stage variable frequency speed regulation scheme. The loop valve is fully closed, and the potentiometer is used to adjust the frequency conversion speed. According to the pressure required by the system load, the motor speed is adjusted in real time, so as to adjust the roots blower Purpose of air pressure. Therefore, the electric energy consumed on the valve can be effectively saved. This scheme is simple to implement and easy to operate. It can not only keep the pressure constant, but also save electric energy.