light industry

一、Brief description of working principle of air compressor
The working principle consists of a pair of mutually parallel teeth combined with the rotor (or screw) in the cylinder rotation. Continue to produce periodic air volume change of the rotor slot between the air, air is along the axis of the rotor by the suction side conveyed out of the side, screw type air compressor suction, compression and exhaust process. Air compressor air inlet and the air outlet are respectively arranged at both ends of the and female rotor slot, the female rotor slot is the male rotor tooth is main drive motor and rotating. The main motor power of the original air compressor is 45KW, a total of three units. Operation mode for the star angle decompression starting at full pressure operating body. Specific procedures: press the start button, control system connected to the starter coil and open the oil cut-off valve, air compressor in unloaded mode start, then the intake valve in the closed position, and the bleeder valve open to the pressure in the discharge of oil gas separator. Wait for 2 seconds after the air compressor began to load the operation, the system pressure began to rise. If an air pressure is not enough to start second, and then not enough to start third. If the system pressure rises to the upper limit of the pressure switch value, namely the take-off pressure, the controller causes the valve, oil and gas separation on the bleed, no-load operation of compressor, until the system pressure down to pressure switch threshold value, namely rebound pressure, the controller causes the intake valve open, oil and gas separation device purge valve closed, open the compressor, oil and gas gas separator valve closing pressure closed compressor run at full capacity.

二、Problems in the original system conditions
Although the 1 main motor starting at the angle of the star, the current is still very large, it will affect the stability of the power grid and the operation safety of other power equipment.
2 the main motor is not running, it is a non economic operation, energy waste is serious.
3 main motor power frequency operation of the air compressor running a lot of noise.
4 main motor power frequency starting equipment, the impact of large motor bearing wear, so the equipment maintenance work on a large amount of machinery.

三、Transformation scheme of frequency conversion
(1) the principle of transformation scheme by transducer, pressure transmitter, a motor, a spiral rotor composed of closed loop pressure control system automatically adjust the motor speed, the air storage tank air pressure stable in the set range, constant pressure control. The feedback pressure and the set pressure are compared, which can control the output step of the frequency converter in real time, so as to adjust the speed of the motor, so as to stabilize the air pressure in the air storage tank.
2. According to the problems existing in the original working condition and the requirement of the production process, the system of the air compressor frequency conversion system has the following functions:
(1) the motor frequency conversion operating state to maintain the stability of gas storage tanks, pressure fluctuations can not exceed the range of + 0.02Mpa;
(2) the system should have two sets of control circuit of frequency conversion and power frequency;
(3) the system has two sets of control loop, open loop and closed loop control;
(4) a frequency converter can control three air compressor units;
(5) according to the working conditions of the air compressor, the system should ensure that the motor has the characteristics of constant torque operation;
(6) in order to prevent the non sinusoidal interference air compressor controller, the input of the transducer should have the effective measures to restrain the electromagnetic interference;
(7) in the case of small electrical quantity, the frequency converter is in low frequency operation, should guarantee the motor winding temperature and motor noise does not exceed the allowable range;
(8) taking into account the system after the expansion of the problem, the inverter 55KW to meet the requirements of the future expansion of the working conditions;
3, system debugging
Debugging work is divided into two parts:
First, according to the requirements of the process, motor parameters, load characteristics of pre tune converter parameters.
Second, system linkage debugging. After setting the parameters of the frequency converter to adjust the number of parameters and no-load running, the system linkage debugging.
Main steps for debugging:
(1) the frequency converter access system.
(2) the operation of power frequency bypass.
(3) the operation of the frequency conversion circuit, including the open loop and closed loop control two parts debugging:
Open ring: some of the main frequency of the frequency of the frequency of the inverter, equipment, the sound is normal, air compressor pressure rise is stable, the pressure indicator is normal, equipment downtime is normal, etc.. If everything is normal, it can be closed loop debugging.
The lifting of the closed loop: mainly based on frequency increases with the decrease of velocity and pressure of air compressor to match, do not produce pressure oscillation, but also pay attention to the observation point of mechanical resonance, will be near resonance frequency jump in the past.

四、Efficiency of frequency conversion of air compressor
1 energy saving inverter control compressor compared with the traditional system of compressor, energy conservation is the most practical significance, according to the demand for air demand to supply the compressor condition is the economic operation of the.
2 operating costs reduce the operating costs of traditional compressors by three components: initial procurement costs, maintenance costs and energy costs. In which the cost of energy accounts for about 70% of the cost of the compressor. Through the energy cost reduction of more than 30%, coupled with the frequency of the impact of the device after the start of the reduction, maintenance and maintenance of the volume also follow the reduction, so the running costs will be greatly reduced.
3 to improve the pressure control precision frequency control system with accurate pressure control. The air pressure of the compressor is matched with the amount of gas required by the user air system. The output of variable frequency control compressor is changed with the change of motor speed. As the frequency control of mechanical and electrical speed accuracy is improved, so it can make the network system pressure changes remain within the scope of the requirements, effectively improve the quality of the working conditions.
4. Extension of the service life of the compressor inverter from OHZ starting compressor and its starting and acceleration time can adjust, thereby reducing superconducting advised to compressor, electrical and mechanical parts caused by the impact, enhance the system's reliability, prolong the service life of the compressor. In addition, variable frequency control can reduce the starting time of the unit current fluctuations, this wave current will affect the power grid and other equipment, the inverter can effectively reduce the peak of the starting current to a minimum.
5. Low noise of the air compressor according to the requirements of the working condition of the compressor, frequency adjustment after the transformation, motor speed slowed down, so effectively drop air compressor operation when the noise, according to previous experience in field test showed that, the noise and the original system decreased compared about 3 to 7 dB.

五、equipment investment

Serial number Device name    Specification model           Place of Origin    Company   number    Unit price (yuan)  Price (yuan)

1    Frequency conversion system cabinet  2200*1200*600GGD   Changsha   Sets      1     total

Special note:
1 the control cabinet with a David chuangfei ECF100-T3-55KW converter;
2. The control system is the core of the air compressor control system, the Yi Chong Fei ECF100 series inverter dragged three control greatly save investment cost, investment benefits and inefficient. The system is used in all kinds of speed control system, the energy saving effect of up to 20-50%, in the absence of other factors under the influence of the general ceiling.

六、Payback period of investment
1. Air compressor to save electricity 45KW fan to run frequency is 40Hz, for example, 80% of the work speed of, consumption of the motor shaft power each year for the Pz=0.83Pn=0.512Pn on Dec. meter, by 30 days of a month, every day according to the 24 hours, considering all kinds of loss after saving 30% calculation: W=45 * 12 * 30 * 24 * 30%=116640 kilowatts to the calculation of electricity price 0.5 yuan per kilowatt hour, the annual province electricity 116640 * 0.5=58320 yuan.
2 to save maintenance costs;
3. Investment payback period of 12 (months) *41500/58320=12 83019 152%=8.5 (month) converter service life of up to 10 years or more, only count the motor power part, about 8 months can recover the full investment, an investment, long-term benefit. Variable frequency speed control technology is a new technology, in the motor drive has very good energy saving effect, variable frequency speed control technology is adopted, to vigorously promote technological progress of enterprises, all-round improve enterprise comprehensive benefits.

七、Yichuangfei application of inverter in air compressor on the fly

User unit            Use power range            entry name

Changsha flag pharmaceutical   ECF100-T3-90KW、160KW      Energy saving constant pressure control system for high pressure machine

Changsha Jiangsu       ECF100-T3-132KW两台        Energy saving constant pressure control system for high pressure machine

Wuhan beer factory       ECF100-T3-132KW、160KW     Energy saving constant pressure control system for high pressure machine

Huangmailing Phosphate group    ECF100-T3-55KW四台        Energy saving constant pressure control system for air compressor