• 2024/11/5 8:57:56

Knowledge of compressor control system

Regardless of the industry, the efficient operation of compressed air systems is essential to reduce operating costs and ensure stable operation. Compressor control devices play a key role in achieving high performance and efficient operation of compressed air systems. In this article, we will explore compressor controls, their types, and their importance in maximizing the efficiency of compressed air systems.

First, air compressor control device

1. Unloading/load control

This control is simple and effective, using the pressure switch at the exhaust of the screw compressor, the intake valve is completely closed when the upper pressure is reached, and the intake valve is completely opened when the lower pressure is reached. The difference with modulation control is that the air compressor under this control implements internal unloading. The decrease of pressure ratio leads to the decrease of useless work consumption. This type of control can be easily connected to multiple air compressor equipment using a sequencer controller. On the other hand, the air system requires the installation of a properly sized compressed air tank.

2. On/off control

This is the most effective control scheme. Screw compressors either run at full load or stop, depending on the signal at the pressure switch. Unfortunately, more than 10hp of the motor if in accordance with the requirements of this control often start and shut down will cause overheating. This control is often used in small piston air compressors with storage installed. The pressure difference of this piston type air compressor is relatively large, up to 15Psig to 25Psig.

3. Variable speed control

Advanced and economical technology brings variable frequency drive technology to screw compressor applications. The principle is seemingly simple, that is, the speed of the motor of the screw compressor is precisely controlled according to the system requirements. When properly designed, frequency conversion control is the most advanced and energy efficient fine screw compressor control. However, the following problems must be addressed.

The screw compressor host should be designed to have high efficiency in the entire speed range. The efficiency of the main engine is a function of the linear speed of the rotor tooth tip, which can be significantly reduced at too low or too high speed.

The variable speed drive controller, as the collar connection between the power supply and the drive motor, must be sufficiently efficient. Drive systems and motor cables must be free from electrical distortion and electromagnetic radiation to avoid electromagnetic interference with computers or other sensitive electronic equipment. The drive motor must be as efficient at high speeds as it is at low speeds, where bearing design and cooling issues can be troublesome.

The intelligent controller creates an efficient and reliable link between the air pressure, the motor and the screw compressor intake valve. A well-designed device can accurately control the exhaust pressure of the screw compressor to within 1Psig, although the gas demand fluctuates over a wide range.

The variable speed control is suitable for adjusting the operation of multiple screw compressors. It allows the sequencer controller to operate efficiently in parallel screw compressors. According to the demand, part of the screw compressor is fully loaded, and the rest of the screw compressor is on standby, and the variable speed control can effectively make up for the fluctuation of the air demand.

4. Constant speed air compressor control

As the name suggests, this method is to keep the screw compressor speed constant, the specific speed is determined by the speed of the drive motor and the transmission ratio function of the transmission device, which can be a gear or a triangle belt. The gas transmission control is based on modulation control or lift valve control.

5. Modulation control

This form of control adjusts the intake valve of the screw compressor according to the exhaust pressure of the screw compressor. When the controller detects an increase in exhaust pressure, it begins to close the intake valve. Although this control is effective, it is the least efficient. The reason is that the efficiency of the screw compressor is inversely proportional to the pressure, and the pressure ratio is the ratio of the exhaust pressure to the intake pressure. The closed intake valve creates a vacuum at the inlet of the screw compressor, while the exhaust pressure is relatively unchanged, which is equivalent to increasing the pressure ratio.

6. Variable displacement control

Controlling the effective rotor length can change the displacement of the screw compressor. It is mainly achieved by adding a cone valve or a spiral valve on the main engine to control the internal bypass. Although the efficiency of this control is better than the modulation control, the spiral valve control is effective only when the capacity is above 60%, and the debugging of this control is complicated and difficult.

Second, what is the use of compressor control device?

Compressor control devices play a vital role in ensuring efficient operation of air compressors and avoiding unplanned shutdowns.

Modern air compressor controllers are some of the most advanced systems, due to the high complexity of the compressed air system they control, these controllers have powerful processing capabilities and offer a variety of advanced connection solutions. The control system consists of sensors and electrical components that monitor and adjust the power output of the motor.

The control system uses PLC and HMI to automatically control the speed of the drive device, which affects the output of the compressor. The compressor control system can adjust the intake valve, control the throttle intake and maintain a certain pressure to ensure that the compressor output reaches the desired level. When a component fails or the working condition is unsafe, it can be automatically shut down. Networked control is suitable for industries that require multiple compressors to work together, one of which is the primary compressor and the others are auxiliary compressors.