Air compressor air supply system energy saving measures
Energy-saving and environmental protection technology version air compressor air supply system energy saving measures Hao Xuqing (Henan Shenhuo Coal Industry Company Yongcheng Aluminum Plant, Yongcheng, Henan 476600) In the production of electrolytic aluminum enterprises, compressed air is mainly used in aluminum transportation, electrolysis, In casting, carbon production and purification systems. Yongcheng Aluminum Plant has an annual production capacity of 460,000 t/year of electrolytic aluminum. There are 15 piston air compressors for production, model 100/10-a. There are 3 air compressor stations in the compressed air system: 1 air compressor station has 5 Taiwan air compressor, 2 air compressor station 3 air compressors, 3 air compressor stations 7 air compressors, electrolysis for two series, respectively, 350kA and 400kA 4 electrolysis workshops, two aluminum warehouses, aluminum The conveying adopts two conveying modes of dense phase and ultra-dense phase, which are divided into two lines of electrolysis and material supply. The air compressor unit adopts the grid-connected operation mode, combined with the adjustment of the load to control the gas volume and output pressure. The air compressor station equipment is arranged as shown.
I. Energy-saving analysis of compressed air flow process When fluid flows through pipes and equipment, part of the mechanical energy of the fluid is converted into heat energy, resulting in work loss; high-pressure gas is lost through the throttling device for functional force. According to the first and second laws of thermodynamics, it can be proved that there is no heat and work exchange between the fluid and the outside, but there is a pressure drop in the flow process, and there is a work loss, that is, the solution flow process, the entropy change of the flow is the total entropy change, and also the entropy of the process. Generated, so the loss of the flow process, because of its flow, temperature and specific volume have not changed much, so it can be simplified: from equation (2) can be seen, to reduce the work loss of the flow process, it should Minimize the driving force of the flow process, which is to reduce the pressure drop. Therefore, when installing the pipeline, it is necessary to minimize the elbows, warp and throttling devices on the pipeline.
In addition, the pressure drop (PrP2) is roughly squared with the velocity, that is, the loss work of the flow process is roughly proportional to the square of the flow velocity, but reducing the flow velocity increases the pipe diameter and increases the cost.
The relationship between the state parameters of air during compression is PFn=cnSt (constant), so when the temperature is constant, the higher the P2, the smaller the value. Therefore, when the operating pressure of the system is lowered, the power consumption is decreased, and the volume flow rate is correspondingly increased.
Under the premise of satisfying most of the unit's gas pressure, reducing the system operating pressure has obvious energy saving effect.
Assuming that a heat exchanger does not account for heat loss, high-temperature fluid A transfers heat to a low-temperature fluid B of temperature rB at a temperature of 7\, high-temperature and low-temperature fluids in March 2013 | China Equipment Engineering Technology Edition Energy Conservation and Environmental Protection The temperature rA, rB can be constant temperature, or it can be changed to SrA>rB. According to the first law of thermodynamics, the heat released by the high temperature fluid is the heat obtained by the low temperature fluid* (B, BP| Second, the economic operation factors of the air supply system 1. Reasonably stipulate the upper and lower limits of the total exhaust pressure The lower limit of the total exhaust pressure is determined according to the pressure value specified by the gas equipment and the pressure loss value of the pipe network. The difference between the upper limit of the total exhaust pressure and / is the margin. Since the amount of compressed air consumed by the pneumatic machine and the blower is proportional to the intake pressure, reducing the margin of the compressed air pressure can reduce the consumption of compressed air and achieve energy savings. In 2010, the coal industry company specified the total exhaust pressure of 0.62±2011. The total exhaust pressure was changed according to actual needs. 55±0.03MPa, the energy saving effect is very obvious. (2) Reduce process resistance and improve intake conditions. Through the improvement of the operation system and maintenance system, the sewage in the drainer is removed in time, and the accessories such as the filter and the high-efficiency filter are cleaned in time to reduce the intake air temperature, reduce the resistance of the filter, increase the displacement, and reduce the work. Consumption. In addition, by modifying the local pipe network and matching the best pipe diameter, the best flow speed can be obtained and the pipe resistance loss can be reduced. 2. Reduce leakage loss and control the total flow of compressed air (1) Reduce the leakage loss of the air compressor. 1 reduce internal leakage. The internal leakage is caused by the helium gas in the air chamber of the air compressor cylinder. In order to reduce internal leakage, the clearance between the piston ring and the cylinder should be controlled within the specified range; when assembling the piston ring, the positions of the slits should be staggered, and all the positions of the slits should be staggered from the valve port. Before the piston ring is used, it should be checked for leaks in the cylinder. It is required that there should be no more than two leaks on the entire circumference. The arc length should not exceed 25°, the total arc length should not exceed 45°, and the light leakage should be greater than 30°. . 2 reduce external leakage. The external leakage is mainly caused by the poor sealing of the compressor packing. Therefore, it is required to regularly inspect and adjust the packing to have good performance, and the assembly position of each sealing ring must also be correct. (2) Reduce pipe network leakage and control total flow. Adjust the total gas consumption in a timely manner according to actual needs. And the leakage of the pipe network is zero, so that the gas consumption is equal to the total output of the compressed air, and the air compressor has the highest energy efficiency. Therefore, in actual production, it is necessary to regularly check the air leakage condition of the air supply pipe network and the wind condition with the wind point, and eliminate the leakage point in time to prevent the waste of the pressure air. (1) Control the air compressor inlet air temperature. The intake air temperature directly affects the operating efficiency of the air compressor. The higher the intake air temperature, the lower the air pressure efficiency and the higher the power consumption. It is recommended to take cooling measures such as sunshade at the air inlet in summer. (2) Regularly check the cooling system. The formation of scale on the surface of the air compressor cooling device is the main reason for the cooling effect. Therefore, the cooling system pipe network should be periodically pickled and descaled. The original design is an inter-plug cooler. The water channel is easy to block and leak, resulting in poor cooling efficiency. The secondary air intake temperature is often around 70 °C. The air compressor has two rows of over-temperature phenomenon frequently, and the compressor operation is serious. Hidden dangers. After 2007, it was transformed into an external spiral tube cooler every year, which increased the thermal area and made the equipment easier to maintain. After the transformation, the secondary air intake temperature is below 40 °C, the compressor operation is stable, and the over-temperature and leakage faults become less.
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