Energy saving method and practical application of air separation equipment
At present, the energy consumption status of three sets of air separation equipment (2, 3, 4 air separation equipment) of Lingang Power Plant can be seen as the use of 6000 m 3 / h (3), 12000 m 3 / h (4) air separation equipment The structured packing is subjected to tower rectification, pressurized turboexpander refrigeration, molecular sieve adsorption purification process, and the operating energy consumption is low. 1 Keep the air compressor running efficiently (1) Select high-efficiency production units that adopt advanced pneumatic design, use high-quality materials, and implement excellent manufacturing and installation processes. (2) High-quality installation level can ensure good lubrication performance of air compressor and high mechanical transmission efficiency, which is an important prerequisite for high-efficiency operation of air compressor units. If the oil pressure or oil temperature is too high or too low, the air compressor unit will be in an unsafe operating state. (3) Improve the isothermal efficiency of the air compressor unit, so that the energy consumption is greatly reduced. In order to ensure the cooling effect of the intercooler of the unit in the summer, it is necessary to strengthen the inspection to prevent and eliminate the blockage of the intercooler. This requires softening and cleaning of the water and cleaning the filter in time. (4) Eliminate the scaling of the impeller, pipeline and volute in time, and rebalance the impeller during regular flushing or overhaul to ensure the unit has good aerodynamic performance. (5) Regularly check and replace the filter cartridge before the machine, and use a high-efficiency self-cleaning air filter to increase the pressure in front of the air compressor. Under the premise of meeting the gas demand requirements, the compressor compression ratio should be reduced as much as possible, the pressure before the machine is increased, the pressure behind the machine is reduced, and the energy consumption is reduced. In order to prevent the further increase of the resistance of the self-cleaning air filter, the air filter of the 12000 m 3 / h air separation unit air compressor is closed to change the air flow direction. The effect of this measure is obvious, the resistance of the matching air filter is between 0 067 1 8 kPa. 2 Optimize the production organization, reduce the inefficient release in the peak of production gas, and play the maximum potential of air separation equipment for gas supply; (1) Make full use of the oxygen and nitrogen reserve capacity of Lingang Power Plant's products, supplement the storage capacity of storage tanks and spherical tanks, and use the reserve products oxygen and nitrogen when the demand for production gas is large. (2) Using the 12000 m 3 / h air separation plant with large load adjustment range to reduce gas production, produce liquid oxygen, and stop the production of 2 air separation equipment with high energy consumption when the reserve capacity is saturated. (3) Minimize the rate of release before and after the oxygen compressor and nitrogen compressor, and if necessary, release the machine before the machine instead of releasing it after the machine to reduce the invalid compression loss of the oxygen compressor and the nitrogen compressor. 3 reduce various losses and reduce various losses, including material loss and cooling loss. Since the production of materials and cooling costs consumes production resources, various losses increase energy consumption. (1) Reduce various leakage losses and reduce invalid leakage of various gases and liquids. For example, after the air separation plant of Lingang Power Plant was gradually changed to the molecular sieve adsorption purification process, the switching loss was gradually reduced. (2) Improve material utilization rate and adopt reasonable working condition adjustment means to increase oxygen extraction rate and reduce oxygen unit energy consumption. (3) Using high-quality insulation materials, add pearl sand to the cold box in time, and install insulation materials on the cold box equipment such as cooling water pipeline, nitrogen water pre-cooling system and molecular sieve purification system to reduce various cooling loss. (4) Improve the use of reflux gas and reduce unnecessary gas venting:! In the current air separation plant process, although the nitrogen is partially used, most of it is still vented, and the remaining amount of nitrogen should be used as far as possible to enter the cooling tower. The molecular sieve adsorber has an ineffective venting for about 25 minutes in one switching cycle (4 hours), and about 80 m 3 / h of air is vented during pressure relief. It is recommended that this part of the gas be sent to the water cooling tower or the cold water tower for use, and the amount of gas entering the water cooling tower controlled by the automatic control device is increased. On the basis of ensuring the cooling effect of the water cooling tower, the remaining sewage nitrogen is sent to the cold water tower for use. ? When the subsequent system is in a production trough, the product oxygen and nitrogen will be vented. It is recommended that this part of the gas be sent to the cooling tower for use. The water vapor ratio of the water cooling tower is controlled so as to avoid ineffective water spray and waste cooling water when the gas volume is large or the scale inside the tower is fouled. (5) Reduce liquid leakage caused by various reasons. Since the unit cooling capacity required to produce a liquid is much larger than that of a gas, the production of a cryogenic liquid requires more production resources. If liquid oxygen is leaked at a rate of 1 L/min, the increased total cold loss will be compensated for by an expansion of about 600 m 3 /h. 4 reduce the blockage and improve the heat exchange efficiency of each heat exchanger. As the blockage will cause the pressure of the compressor to rise, the energy consumption of the compressor will increase. At the same time, the heat transfer efficiency of the heat exchanger will decrease, or the heat loss will be caused by the bias flow. Since a certain product oxygen and nitrogen must have a certain amount of cooling guarantee, the decrease of heat exchange efficiency will inevitably lead to an increase in materials and energy consumption. (1) Discharge the main cold non-condensable gas in time to enhance the heat exchange effect; regularly discharge the main cold liquid oxygen to avoid the accumulation of hydrocarbons and various impurity powders and affect the heat transfer effect. (2) Adjust the temperature in the middle of the heat exchanger, and it is required that no cold loss or no bias current is generated. Reduce the temperature difference at the hot end and reduce the incomplete loss of heat exchange caused by heat exchange. In large air separation equipment, the cooling loss accounts for more than 40% of the total cold loss. If the hot end temperature difference increases by 1, the total cold loss will increase by about 16%, which requires increasing the expansion of the expander to compensate. (3) Control the air dew point temperature after the molecular sieve adsorber, and prevent the moisture from entering the plate-fin heat exchanger to affect the heat transfer effect; the molecular sieve regeneration is thorough, and the air resistance of the molecular sieve adsorber is reduced; the molecular sieve regeneration gas heater should be operated as much as possible Avoid frequent start and stop, it is best to start and stop with a small power electric heater. (4) Regular cleaning and pickling of the air pre-cooling system can reduce the resistance and adjust the appropriate water vapor ratio. The nitrogen water pre-cooling system of the 2 air separation plant is modified into a group cycle, the air cooling tower 1 section utilizes large circulating water, the 2nd section and the water cooling tower and the chiller form a small cycle, which is beneficial to enhance the heat exchange effect, reduce local scaling and reduce Refrigerator energy consumption. 5 Optimized operation to reduce energy consumption When the air separation plant is in normal operation, adjust the working conditions to reduce the pressure on the upper tower, reduce the amount of air in the tower, play the unit cooling capacity of the expander, and exert the throttling effect cooling capacity to maximize the product extraction rate. Reduce energy consumption. (1) Reduce the pressure of the upper tower, reduce the pressure of the lower tower and the pressure behind the machine, make the separation of oxygen and nitrogen easier, and adjust the opening degree of the throttle valve reasonably, so that the material extraction rate is maximized and the energy consumption is reduced. (2) Since the total cycle power is the difference between the energy consumption of the air compressor and the power consumption of the expander, if the cooling capacity of the main tower normal rectification is to be met (ie, the total cycle work is constant), the maximum unit refrigeration of the expander should be utilized as much as possible. The amount meets the total cooling capacity and reduces the energy consumption of the air compressor. If the amount of expansion air entering the upper tower is too large, so that the upper tower load is increased (the rectification capacity is full) or the superheat is too large, the upper tower reflux ratio is further changed, so that the upper tower rectification section is overloaded, resulting in extraction. The rate is reduced; the appropriate amount of expansion air and superheat will further excavate the distillation potential of the upper tower, so that the efficiency is the best and the energy consumption is the lowest. For turboexpanders with fans, the expansion of the expander should be as close as possible to the best rated speed through the adjustment of the nozzle and the fan section valve, so that the expander has the highest entropy efficiency. For the turbocharged turboexpander, the amount of expansion air entering the tower should be reduced as much as possible. The adjustment of the nozzle and the booster section valve allows the expander to operate at the optimal rated speed, so that the recovery work and the cooling capacity are at the maximum equilibrium. 6 Reducing the consumption of water, electricity, lubricating oil and other materials The energy consumption of air separation equipment includes various energy consumption. The power consumption of the operating equipment includes air pressure electromechanical consumption, water pump power consumption, refrigeration electromechanical consumption, and oil pump power consumption. Take 2 air separation equipment as an example: air compressor motor power 2240kW, air pre-cooling system refrigerator power 37 kW, pump power 30 kW, each pump power total 14 kW. Reduce the various operating power consumption of each equipment, so that the total product The unit cost is reduced and the economic benefits of the entire company are increased. 7 Conclusion Through the analysis of the energy consumption status of three sets of air separation equipments in Lingang Power Plant, the corresponding measures have been taken in the selection, operation and maintenance of equipment to make energy-saving equipment reduce energy consumption and increase economic benefits for enterprises. It is hoped that the energy consumption of the air separation plant will be lower by further optimizing the operation in the future. Organic fertilizer is different from traditional fertilizer. Ihe source of organic fertilizer is from plant, animal, or mineral that is applied to plant without any processing. It plays an important role in the sustaining development of agriculture. Organic fertilizer . 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