The common air compressor uses power frequency motor, and the frequency adjustment range is only 25-50HZ after adding a frequency converter, which basically can not save energy and only achieves the soft start function. However, in actual use, the motor is often burned down because the cooling fan connected with the motor reduces the speed at the same time after the motor speed decreases, resulting in great loss of heat dissipation effect.
Answer: 1. There are two pole asynchronous motors and four pole asynchronous motors. The speed of the four pole motor is 1450 rpm, and the speed of the two pole motor is 2900 rpm. Both are cooled by the motor connected fan. The air compressor generally adopts a two-pole asynchronous motor, with power frequency speed of 2900 rpm, frequency conversion of 25-50HZ, and speed of 1450-2900 rpm, reaching the design speed of the coaxial cooling fan of the general motor, and sufficient cooling air volume.
2. Almost all air compressor manufacturers have a series of frequency converters, which are energy-saving models. The energy-saving benefits are beyond doubt. Our company has developed several generations of air compressor frequency conversion energy-saving system, and the energy-saving effect has been verified by a large number of examples.
3. Special models can also install fans at the end of the motor to increase the fan heat air volume to solve the problem of overheating of the motor.
The main engine of the air compressor inevitably has gas leakage in the triangle leakage area, especially the linear screw of the ordinary air compressor designed to operate at full load. When the rotating speed is forced to be reduced, the leakage in the triangle area is extremely expanded, resulting in the phenomenon of air flow reversal, resulting in air flow disorder, greatly reducing the gas production and increasing the vibration rate of the main engine, resulting in an increase in the failure rate of the main engine and affecting the service life of the bearings and the main engine.
Answer: 1. The triangle leakage area of the main engine of the air compressor is located in the oil-free screw compressor where the rotor does not contact. When the oil injected screw air compressor works, the rotor compresses not pure crushed air, but a mixture of oil and gas foam. The air compressor oil plays a sealing and cooling role, and there is no air leakage and reverse channeling.
The set oil injection quantity of the main engine of the ordinary air compressor is constant, and the oil injection quantity will not be automatically reduced in time because the screw speed decreases and the temperature of the main engine decreases. Continuing to use the full oil quantity of lubricating oil will cause serious emulsification, resulting in water content in the system, which will greatly damage the bearings and the main engine, and greatly shorten the service life of the equipment components and the whole machine.
Answer: 1. The oil circulation volume of screw air compressor is determined by the screw speed, which is high in speed, high in oil volume, low in speed and low in oil volume.
2. The air compressor head and lubricating oil temperature are controlled by cooling temperature control valve and fan, and the general working temperature is 70-90 ℃. There is no problem of water emulsion caused by low oil temperature.
The common air compressor usually uses PID closed-loop program control system. The added frequency converter control system and the pressure signal sensing system of the machine can not achieve a good synchronous match, which will cause a series of phenomena such as slow and disordered signal transmission and frequency disorder during operation, and increase the equipment failure rate. The air compressor manufacturer generally does not support the installation of external converter.
Answer: 1. The ordinary air compressor does not use the PID closed-loop control system, but the loading and unloading control mode, which is: when the pressure reaches a certain value, the air compressor closes the inlet valve, unloads, and does not exhaust, the air compressor motor still runs, wasting electric energy; When the pressure drops to a certain value, re-open the inlet valve and load the exhaust.
2. The frequency conversion system added to the air compressor is the PID closed-loop constant pressure control, which has no essential difference from the manufacturer's frequency converter series.
3. The frequency conversion intelligent power saving series of air compressor designed by our company is not a simple external frequency converter, but a complete and independent intelligent equipment. The hardware part is completely independent, such as air switch, contactor, etc; The software program part needs to access the signal of the air compressor to determine the frequency of the frequency conversion action through the fluctuation of the peripheral air pressure demand, so as to achieve the energy-saving effect of the air compressor. In addition, in the actual use process, the air compressor has not only lost the original state of starting and stopping, but also has not changed a lot of speed fluctuations. It can almost reach the state of constant pressure gas supply and relatively constant speed operation.
The addition of frequency converter is generally only suitable for the transformation of single-stage compression air compressor, and two-stage compression is particularly not suitable, because bipolar compression is driven by a small power motor through large and small gears to drive the overload operation of two main engines. After the transformation of frequency converter, it is more likely to cause the phenomenon of fever motor and greatly reduce the transmission efficiency.
Answer: 1. "One small power motor drives two main engines to operate with overload through large and small gears" -------- If the main engines of the compressor in normal operation are overloaded, it will not be able to operate safely and stably for a long time. This is a problem in the design of the compressor. Neither power frequency nor frequency conversion can achieve the optimal operating conditions.
2. The normally designed twin-stage screw compressor is driven by gears and changes speed synchronously. The compression efficiency of the two main engines is the same, and there is no problem of reducing the transmission efficiency. Double-stage screw compressors sold on the market also have frequency conversion energy-saving series.
Source: Xianbo Energy Conservation
