Analysis on Energy Saving Potential of Compressed Air System in Industrial Enterprises

Compressed air is one of the most widely used sources of power in modern industrial processes, and is responsible for supplying air to all pneumatic components in the plant, including various pneumatic valves. At the same time, it is also the first type of energy carrier that consumes a lot of energy in most production companies. The compressed air system consists of air compressors, air handling and sound distribution, conveying pipe network, cooling and sound setting, and air conditioning. The air is used as the medium to produce compressed air. Most of the sounds are driven by electricity, and the power consumption accounts for 10% to 40% of the total power consumption of the enterprise. The air compressor consumes more than 90% of the system's power consumption. Currently, most of China's enterprises compress air systems. Energy harvest date: 2011 usage rate is low. The following problems are common: air compressor manual switch machine, frequent loading and unloading, long-time unloading can not automatically stop, compressed air supply pressure is unreasonable, pipe network pressure loss and leakage, gas grab nozzle inefficiency and cooling water valve manual operation. The energy-saving problem of compressed air systems has become a research hotspot for air compressor manufacturers and users.

This paper takes an industrial enterprise air compressor station as an example to analyze the energy saving potential of some key energy-saving points of the air compressor system, establish a mathematical model, and calculate the energy cost that can be saved. The results show that the analysis of energy saving potential has guiding significance for enterprises to carry out energy conservation work. By adopting a series of energy-saving measures, enterprises can effectively increase energy savings and reduce energy costs.

2 Compressed air system energy-saving analysis model Air compressor is the main set-up of converting electric energy into compressed air pressure energy. Due to long-term continuous operation, its efficiency directly affects the consumption of electric energy. H. The power consumed by air compressor operation can be According to the rated power, running time and operating efficiency of the motor, set the motor operating efficiency to 100%, calculate the P-installed power according to the following formula, kWt-the total operating hours of the air compressor, hn negative-loading rate, air compressor load operation The ratio of the number of hours to the total number of hours of operation n empty - no-load rate, the ratio of the number of empty running hours of the air compressor to the total running hours k - the no-load power consumption coefficient, the air compressor consumes the full load when it is empty The proportion of power consumption, 30% for the common air compressor manual switch machine, the long-term unloading can not automatically stop, the supply pressure is unreasonable and the network pressure loss and leakage four prominent problems. Set the energy saving potential of the company's 4 problems to 4Qi, 4Q2, 4Q3, 4Q4, the unit is kWh, then the total energy saving potential AQ is “air compressor manual switch machine energy saving potential AQ2—air compressor can not be automatically uninstalled for a long time Energy saving potential AQ3-compressed air supply pressure unreasonable energy saving potential AQ4-pipe network pressure loss and leakage energy saving potential Energy saving potential corresponding to energy saving potential is AS, the unit is yuan, then the current saving of most air compressors The sound is manually switched on and off, and there is no automatic start and stop control function. The manual switch machine has the following problems: (1) The booting is too early, the generated compressed air can not be used in time, resulting in energy loss; (2) The startup pressure is not timely, the production compressed air pressure is not enough, affecting the production effect; (3) Shutdown is not Timely increase air pressure, increase load current, and increase energy consumption. Among them, problems (1) and (3) will lead to an increase in air compressor operating time and waste of energy. When the air compressor is turned on, it runs at full load, and when it is turned off, it runs at no load. If the compressor group expert control system optimization technology is adopted, the switch machine time or pressure point is set to realize the function of automatic switch machine, so that the switch machine can accurately control and can effectively Reduce the consumption of electric energy AQ1, save electricity costs AS1. 2.2 Unloading operation for a long time can not automatically stop When the gas supply is greater than the end gas consumption, the unit exhaust outlet pressure rises, when the outlet pressure rises above the upper limit of the pressure detection switch At the time, the unit closes the air inlet valve and transfers it to the unloading operation. The information provided by Atlas indicates that for every 0.013MPa of compressed air, the energy consumption is increased by 1%. The output pressure of the air compressor is lowered. 0.1MPa, the energy consumption is reduced by 5%~6%0. Therefore, the air supply pressure of the air compressor is reduced as much as possible under the condition of using the gas pressure, which is beneficial to reducing the energy consumption of the air compressor and saving energy cost. The concept can represent the effective energy contained in compressed air. The calculation formula of pneumatic power is as follows: p—air absolute pressure, MPa Pa atmospheric absolute pressure, MPa q, “volume flow under compression”, L/min is the energy saving potential due to unreasonable compressed air supply pressure, combined with (8) Pneumatic power of compressed air, WP for absolute pressure of compressed air supplied by air compressor, P required - not through pipe network, no pressure loss of pipe network and leakage of compressed air, MPa t - compressed air system running time It can be seen that by reasonably adjusting the air supply pressure of the air compressor, the power consumption AQ can be reduced, and the cost can be saved. A. 2.4 The pressure loss of the pipe network and the leakage compressed air pressure are larger than the air, and the pipe flows through the air treatment equipment and the pipeline due to the pipe. The network layout is unreasonable, the sealing effect is not good, and the leak detection work is insufficient, resulting in pressure loss and pipe network leakage. System leakage often accounts for 20% to 30% of the system's gas production. = Chemicalization - After analyzing the energy saving potential of the above four problems in the enterprise's compressed air system, we conclude that the company can reduce energy consumption AQ and save energy costs. About AS. The following takes an industrial enterprise compressed air system as an example to analyze the energy saving potential of these four problems in the system.

3 Analysis of energy saving potential of an enterprise's air compressor system The compressed air of the production department of an industrial enterprise is mainly provided by the air compressor station of the plant. The air compressor station is now dubbing 3 centrifugal air compressors and 4 screw air compressors. The running data is shown in Table 1.

Table 1 Air compressor parameters and data sequence of a certain industrial enterprise Accumulated output cumulative hours Air compressor model Power voltage Flow pressure Load manual switch machine: The average time for early boot is 78h, the average time for delayed shutdown is 56h; long time unloading The operation cannot be automatically stopped: the average running time of the long-term unloading operation without stopping is 1/4 of the total unloading time of the entire air compressor, which is 814h; the supply pressure is unreasonable: the absolute pressure of the compressed air supplied by the air compressor 0.88MPa; without pipe network, no pipe network pressure loss and leakage of compressed air absolute pressure 0. Flow rate is 133818.11L / min; air pressure system running time is 34400h; pipe network pressure loss and leakage: pipe network inlet compressed air The absolute pressure is 0.83MPa; the absolute pressure of compressed air at the outlet of the pipe network is 0.8MPa; the average flow is 133981.41L/min; the running time of the air compressor system is 34400h. According to the operating data of the above compressed air system, the energy cost model is operated by the air compressor system. Can calculate the energy saving potential, as shown in Table 2. Table 2 An industrial enterprise compressed air system energy saving potential manual switch machine long-term unloading For the four outstanding problems that exist in the compressed air system, the energy saving potential analysis shows that the electricity saved after solving the problem is about 3,085,559.27 kWh; the power cost that can be saved is about 1,691,100 yuan, accounting for 2.58 of the total energy cost of the compressed air system. %. 4 Energy-saving measures 4.1 Compressor group expert control system Air compressor group expert control system has become a new energy-saving technology for air compressor group control. The control system changes according to the pressure demand, centrally control the start and stop, loading and unloading of different air compressors, etc., to keep the compressor with the proper quantity and capacity in the system.

The system has the automatic start-stop control and self-learning function of the voice air compressor, which can reasonably configure the air compressor, balance the running time of each air compressor, and effectively reduce the running time of the air compressor unloading time period. According to the compressor group configuration information, advanced expert control experience can be written into the control algorithm under the premise of ensuring the minimum supply pressure to achieve optimal control, so that the compressor group can run at the lowest energy consumption and the output pressure is stable.

4.2 Compressed air test system to reduce the leakage amount Qin Hongbo et al proposed that the compressed air test system can directly test the system flow, pressure and air compressor power and other parameters (this is the most direct and accurate assessment of the compressed air system leakage) Method 9).

The compressed air test system has the function of monitoring and recording the change data of parameters such as system flow, air compressor power and system pressure. By plotting the pressure gradient curve, the normal resistance of each part of the system is analyzed, and the operating efficiency of the system is evaluated to provide a basis for optimizing the system. 110. The compressed air system test can establish the system operation benchmark, and tap the energy saving optimization potential of the system to successfully apply the energy-saving technology. Provide a reliable basis.

4.3 Online fault analysis and diagnosis technology Online fault analysis and characteristics of the cutting technology: (1) sound performance analysis and fault diagnosis, timely warning and alarm; (2) data acquisition denoising filtering and effectiveness cutting technology; 3) Analysis and evaluation of pressure loss of pipe network to reduce the loss caused by unreasonable pressure drop 4) The leakage of pipe network is reduced, and the amount of gas leakage is reduced. The best way to find a leak is to use an ultrasonic leak detector that can greatly reduce the amount of leakage through preventive maintenance procedures.

5 Conclusions This paper establishes an energy consumption model by analyzing four problems commonly existing in enterprise compressed air systems, and analyzes energy saving potential. Combined with the operating data of compressed air system of an industrial enterprise, the energy saving amount is calculated, and the following conclusions are drawn: there are four outstanding problems in the compressed air system of industrial enterprises. Manual switchgear, long-time unloading cannot be automatically stopped, supply pressure is unreasonable, and pipe network pressure loss And leakage; for such problems, the model can be used to analyze the energy saving potential; the model is applied to a company's compressed air system, and the energy saving potential is about 30,855,592.71 million yuan of electricity cost; the compressor group expert control system, the compressed air test system and Advanced energy-saving technologies such as online fault analysis and cutting-edge technology will carry out energy-saving renovations for enterprises, improve the operating efficiency of air compressors, and increase energy efficiency. Reduce energy consumption. Reduce energy costs.

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