Research and Application of Frequency Conversion Technology of Compressed Air System Based on System Performance Analysis
Because it has clear, transparent, harmless and non-polluting, it is not dangerous to transport; the advantage is that compressed Ningqi is widely used in various fields of the industry, and is called the first energy source. Air compressors account for about 9.4% of China's electricity consumption. However, compressed air is also a very expensive energy source with high operating costs. According to the theory of full life cycle analysis, the cost of purchasing air compressors only accounts for 10 of the total life cycle cost. Around, while energy costs account for around 75. According to the US Department of Energy's 202-year global survey, the average N-gas compressor has a load rate of 79, while the average internal compressor load ratio is 66, which is better than the global air compressor. The average load rate is 13 low, and its operating energy efficiency is larger than that of developed countries. In recent years, as the attention to the global energy situation has increased, the energy efficiency of compressed air systems has also been studied. However, at present, many researchers have a lot of research on how to improve the full-load energy efficiency of the gas compressor system. There are relatively few system researches on the operating characteristics of the air compressor system and how the air compressor is well matched with the system. Through energy-saving transformation. Such as the application of network optimization technology, frequency conversion technology, pressure control technology, etc., many compressed air systems can achieve more than 10 energy-saving effects. However, each compressed air system is different, and the applicable energy-saving technologies are different. It is not possible to blindly implement inappropriate energy-saving technologies. Based on the description of the most widely used screw air compressor control method and corresponding energy efficiency characteristics in the industry, this paper analyzes the effect of frequency conversion technology on improving the energy efficiency of air compressor system.
1 screw air compressor control mode and energy efficiency characteristics The most widely used compressors in the industry are mainly screw rod compressors, which have the advantages of simple structure, safety and reliability, and easy pressure control air compressor load power comparison curve 2 maintenance. The most widely used industrial applications. This paper focuses on the analysis of different control methods for screw air compressors.
Loading, load control Loading and loading control is the earliest control scheme of screw compressor. When loading, the compressor will run at full load. When the system uses less gas, the excess compressed air produced by the compressor will make The pressure of the system rises. When the compressor controller detects that the system pressure reaches the unloading pressure set point, it will issue a retracting pressure valve pressure rate when the load control system is 7 days old and close to 1 meter. Xu Dawei is near the fly instrument, and the defending dragon is carrying a load. At this time, the compressor does not produce compressed air, but the motor is still in operation, and will still consume 25% of the power at full load, which is mainly consumed by mechanical losses and maintenance. Lubricate the normal operation of the system. As the system pressure drops to the lower upload pressure set point, the controller signals that the intake valve is re-energized and the compressor is again operating at full load.
A pressure control device can control the system's pressure fluctuations to within 71. Loading gallery control air compressor load power comparison curve 1.
2 Constant pressure regulation control mode and load-load control air compressor inlet valve Only the full reduction machine maintains the system air supply shutoff by finely adjusting the opening degree of the inlet valve, the air compressor flow rate is reduced, and the compression ratio is increased. The power required to adjust the partial load operation of the reducer is relatively large, and the effect is significantly reduced. The air intake throttle control will completely consume 70 power when the intake valve is completely closed. When the air is at full load 50, the typical power consumption value is about 80 at full negative, so the air intake throttle Control is a very uneconomical way of doing things. In a relatively large compressed air system, the multi-air compressor is running below full load at the same time. Although the system pressure is very stable, the energy efficiency level is very low. Constant load rate 2 variable frequency control system In general, the screw air compressors commonly used in the industry are equipped with motors as small as 22 psi and up to 250 æ . They are mainly cage-type asynchronous motors, which are typical of small and medium-sized motors. The frequency conversion technology can control the speed of the compressor to change the speed of the compressor main unit to match the air supply of the compressed air with the gas phase, thereby achieving stable system pressure and reducing the system flow load, which is not only conducive to the stable operation of the production equipment, but also produces Good energy saving effect.
21 system constitutes the inverter control system 3 consists of the power switch cabinet inverter intelligent, 1 controller and air compressor. The power switch cabinet is installed in the system to ensure the normal operation of the air compressor when the inverter system fails.
22 basic working principle The frequency conversion control system detects the change of system pressure through the pressure sensor installed on the main pipe of the compressed air system and transmits it to the 13 controller. The controller outputs a current signal to the inverter according to the set pressure. When the pressure signal detected by the pressure sensor is greater than the target pressure setting value, 13 controller output motor speed decreases, the air volume delivered to the pipe network decreases, and the system pressure decreases; when the pressure signal detected by the pressure sensor is smaller than the target due to the variable speed drive process There are some inherent losses, so special care must be taken when selecting a variable speed drive compressor. The variable speed drive control mode should be used only as a regulating compressor when the load changes greatly and is rarely used in a fully loaded state. This type of control is most efficient at part load, but when the air compressor is running at full load, the internal losses of the drive reduce the energy efficiency of the control mode.
3Inverter control energy-saving principle According to the law of thermodynamics, when the single-stage volumetric compressor completes the theoretical abdomen of the adiabatic theoretical cycle, the signal output of the controller is enhanced, and the output frequency of the inverter is increased. When the air compressor motor speed increases, the air volume delivered by the air compressor to the pipe network increases, and the system pressure rises, thereby achieving the purpose of stabilizing the system pressure.
Air compressor frequency control motor speed and power frequency power frequency; motor pole pair 23 variable speed drive air compressor energy efficiency characteristics and centrifugal fan pump square torque load is different, air compressor is a constant torque load. Therefore, when the power and speed of the motor are not approximately cubic, but in an approximate power relationship, the power consumption and the percentage change of the load are 4.
Rk compressor discharge pressure, k gas constant.
It can be seen from Equation 2 that a large fluctuation in system pressure means an increase in the average exhaust pressure of the air compressor and an increase in energy consumption. For loading gallery control mode, when multiple air compressors are operated in parallel, the maximum and minimum pressure set points of each air compressor and the nearest compressor have at least aol4MP, scoop differential pressure. According to this method, the originally designed system operating at 0169,075 and daytime will increase the system pressure fluctuation range after increasing the compressor, resulting in an increase in the average supply pressure of the system, and the operating power of the air compressor will also increase. Then give it. At the same time, the number of air compressors is also limited by the maximum allowable system pressure fluctuation range. The system pressure fluctuation range of the general load weeping control is not recommended.
According to a large number of test results, in the case of general industrial application pressure demand, for every increase in system pressure, 1 air compressor power will increase by about 6, and for gas equipment without pressure regulation, the compressed air flow will increase. If variable frequency control technology is applied, system pressure fluctuations are controlled within 2 colonies, which will result in very large energy savings. At the same time, if there are multiple partial load plus load or constant pressure control air compressors in the system, the energy saving effect will be more significant.
4 System performance test analysis Compressed air system flow and pressure dynamic changes very fast, in many systems, hundreds of thousands of air loads run randomly, often leading to imbalance between the supply side and the demand side of the compressed air system, often Now the system has a large pressure fluctuation range or multiple air compressors are in partial load state, which provides a good opportunity for the application of frequency conversion control. However, the variable frequency control air compressor has a certain control range. Only when the flow fluctuation of the system is within its control range, the frequency conversion control can better play the role of energy saving and stable system supply pressure. Therefore, in determining whether a variable speed drive is suitable for use in a compressed air system, the best method is to apply a professional compressed air system test recorder to conduct a comprehensive test analysis of the system.
The test system is mainly composed of a data logger mass flow sensor pressure sensor power sensor and a computer part. 5. The data logger is used to record data signals from the flow sensor pressure sensor and the power sensor; the flow sensor is mainly used for testing system flow, suggestion Use a mass-flow meter installed in a fine plug-in type; a pressure sensor is used to test the pressure change data of the system; a power sensor is used to test the power change of the air compressor; and the computer is used for recorder setting and system data analysis. .
Through the test system, the parameters such as the system flow pressure and the air compressor operating power of the compressed air system including the normal working days and the weekend production conditions in 24 hours or even weeks can be collected. Based on this, the system flow load fluctuation range and variation characteristics are analyzed. Furthermore, it is proposed whether the variable frequency control is applicable and what kind of frequency conversion control scheme is adopted.
5Inverter Control Case Study 51 System Operation Overview The compressed air system of a factory in Shanghai consists of 5 Ingersoll Rand screw systems consisting of 2 Ingersoll Rand air compressors. Each unit's rated gas production capacity is 20 systems with refrigerated and Adsorption dryer and 1 dry gas storage tank.
The system operation mode is open, and the constant pressure control mode operates, mainly supplying gas for production in the filter rod workshop.
System 2 consists of three Ingersoll Rand air compressors, two sets of watts, 0 and 1 set, and the rated gas production of the unit is respectively. The 91-pyeong 10 system is equipped with a refrigerating dryer and a dry and wet gas storage tank. The capacities are 1.5 and 1 respectively, which are mainly used for the production of gas in the carton workshop and packaging workshop.
52 system test analysis system 1 According to the test results, the system output pressure fluctuation range of the system is beyond the normal pressure fluctuation range of the constant pressure control mode. Due to the system configuration, the compressor cannot be placed in the load control mode. In addition, the air compressor is about today.
According to the test results, the system pressure fluctuation range of the system is that the Q4b compressor output flow fluctuates between the oloo, and the average flow rate is about 7.3. The system optimization measures and effects adopt the following transformation plan based on the system test analysis.
Optimize the system piping system to connect two independent pipeline systems to the grid. According to the system flow test results, in the normal production, the air compressor can meet the peak load demand.
The high-efficiency frequency conversion control system is installed to control the air compressor and the air compressor, which not only reduces the number of units that can be turned on, but also improves the efficiency of the air compressor when it is running.
After the system is optimized, the system is tested before and after the switch. It is divided into independent operation and grid-connected power frequency operation and grid-connected frequency conversion operation. The total average power of the test air compressor is 141.7俦029åŸ and 64 network total section respectively. The electric rate is 54.8, and the power saving rate of the variable frequency drive is 27.5.
6 Conclusion Through the different control methods and case analysis of the principle of screw air compressor, the following conclusions can be drawn: At present, many of China's compressed air system energy efficiency has a lot of room for improvement; variable speed drive control is applied properly, and the energy efficiency of the compressed air system is improved. A very effective control method; whether to apply the frequency conversion technology should be determined on the basis of comprehensive diagnosis and analysis of the system.
As explained above, with the strengthening of China's energy conservation and emission reduction, variable frequency drive is of great significance for promoting the improvement of energy efficiency of compressed air systems, and has broad application prospects.
Coupletech Co., Ltd. supply diode-pumped Pulsed solid-state Laser and passive Q-Switched pulse laser models, in particular, athermal diode-pumped Pulsed solid-state Laser 1064nm without temperature control can work from -40℃ to +60℃ and diode-pumped Pulsed solid-state Laser with air-cooling can work from -40℃ to +60℃ for laser distance measuring, and the power is >100mJ for the repetition of 1-100Hz. Passive Q-Switched pulse laser models consist of Mid-infrared laser MP-3200, Eye-safety laser MP-1570, Infrared laser MP-1064, Green laser MP-532, UV laser MP-355, Deep UV laser MP-266, and these products cover a wide range of wavelengths: 3200nm, 1570nm, 1064nm, 532nm, 355nm and 266nm, with operating temperature of 10 ~ 35℃, the average power is 0 ~ 200 mW for the repetition of 20kHz.
Coupletech's Pulsed solid-state laser has advantage of compact athermal resonator design, no significant warm up time, no power consuming cooling system, no diode technology for increased efficiency and long life performance, no high energy with low beam divergence and Shock and viabration hardened.
Diode Pumped Pulsed,Laser Diode Module,High Power Laser Diode,Diode Pumped Laser,Eye-safety Laser
Coupletech Co., Ltd. , https://www.coupletech.com