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Main operational measures to reduce ammonia consumption in small urea production plants using the full-circulation aqueous solution method. For a given small urea production plant, to effectively reduce the ammonia consumption per unit of output, in addition to adopting energy-efficient processes and high-performance equipment in terms of technical upgrades, it is necessary to take measures in terms of process operation in the following areas: 1. Proper operation of the desorption system. (1) To maintain the horizontal balance of the system, it is essential to desorb excess ammonium carbamate solution in order to recover ammonia and eliminate the excess amount; this involves handling 3.33 m3 of ammonium carbamate solution. The urea content in the ammonium carbonate solution is around 1.15%, while the ammonia content is around 6%. Conventional separation systems are unable to desorb urea; for every ton of urea produced, 3.8 kilograms of urea is discharged in the desorption waste liquid. If the desorption waste liquid is of acceptable quality, with an ammonia content of 0.07%, 0.23 kilograms of ammonia are discharged from this waste liquid for every ton of urea produced. It is very important to operate the desorption system properly, in order to prevent the release of ammonium carbonate solution and ensure that the desorption waste fluid meets the required standards ； (2) The second-stage evaporation condensate must not be added to the desorption tower, as this will cause a loss of urea ； (3) Control the desorption pressure, the temperature in the middle of the desorption tower, and the temperature of the gas exiting the desorption condenser (≤112°C) to reduce the amount of water vapor carried into the secondary cooling system, which helps maintain the system’s water balance. Otherwise, too much water in the incoming vapor leads to secondary discharge, increasing the desorption load and creating a vicious cycle. The ammonia loss in the gas phase of the ammonium carbonate solution tank increases, resulting in higher ammonia consumption ； (4) Control the liquid level in the desorption tower properly, maintain a stable flow rate of the desorption liquid, and ensure that the reflux pipe of the desorption condenser is unobstructed, in order to prevent issues related to the desorption process. 2. Make rational use of the absorption liquid: (1) The urea in the ammonium carbonate solution comes mainly from the evaporated condensate. A portion of the evaporated condensate (abbreviated as: primary liquid) contains about 0.0% of that substance, while the ammonia content is around 2.7%. The secondary evaporation condensate (abbreviated as secondary condensed liquid) has a salinity of around 3%, while the ammonia content is about 2.1%; these two types of condensates should be stored separately. 1, 2? Laotian? Mo Mi River κ Zi Rong Mei? Jian Hai? Huai Ao Mu Kang Zhong Mi Huai Jian Han Gou Huan R Hua Wei Xie Mai Huai Meng Ke Hu ⒍? Xian Gou Shuan Jian б Hai? Zhi? Jian б Han Mo Bei? Kang Lu? Wan Zi Fei Sha? Lai Nai Cai? Bei? Kang Zhe ⑽ Can?? Han Shan You Wu? Cai? Ou Nie Bi E г Meng Ying? (2) It is not allowed to add these two types of liquids to the tail suction tower or desorption tower, as this will result in the loss of urea ； (3) Under normal operating conditions, desalinated water shall not be added to the evaporation condensate tank. Otherwise, it will increase the load on the desorption system. (4) The seal water for the ammonia pump can be recycled using deionized water; once it reaches a certain concentration, it is sent to the ammonium carbonate tank. 3. Stabilize the material flow rate in the system and reduce gas entrainment in the separation equipment. (1) Regularly inspect the packing and demisters in the distillation section of the split tower, and maintain an appropriate liquid level in the split tower in order to reduce problems related to liquid entrainment. (2) Maintain an appropriate liquid level in the first cooler as well, in order to reduce liquid entrainment in the gas stream from that cooler. Otherwise, it will lead to an increase in the CO2 content in the secondary cooling ammonia solution, as well as excessive CO2 levels in the gas phase at the top of the first absorption tower, thereby threatening the proper operation of the ammonia cooler ； (3) Control the secondary cooling liquid level at an appropriate level to reduce liquid in the gas phase of the secondary cooling. (4) Control the pressure of the medium-pressure system and the flow rate of the ammonia water pump stably, to prevent liquid from being carried into the tail suction tower by the gas phase in the inert gas scrubber. (5) Control the flow rate of the tail suction pump at an appropriate level, to prevent an increase in the ammonia content in the gas vent. The liquid inflow rate to the tail suction tower is too high… It is necessary to regularly inspect the separation devices in the separator in order to reduce the amount of urea that gets carried along with the liquid. 4. Control a high conversion rate in the synthesis tower: (1) It is important to maintain proper water balance in the system, as well as control the appropriate ratios of water to carbon, ammonia to carbon, and the temperature of the synthesis tower; this helps to minimize waste. (2) Increasing the purity of CO2 and controlling the appropriate amount of air added can help reduce the amount of ammonia consumed by decreasing the amount of gas released from the medium-pressure system. 5. Properly control the first and second stage circulation systems. (1) Maintain an appropriate decomposition temperature for the first stage; the decomposition rate of ammonium methylate and the ammonia recovery rate should exceed 90%. Otherwise, the load on the second stage increases, the load on the tail suction tower rises, and the ammonia loss due to exhaust gas release increases ； (2) The amount of medium-pressure oxygenated air should be appropriate to ensure that the nickel content in urea does not exceed the specified limit. Otherwise, the medium-pressure vent volume will increase. (3) Control the water inflow to the larger ammonia cooler in order to reduce the vent volume from the first stage ； (4) Control the liquid level and composition during the first and second absorption stages; no discharge is allowed under normal operating conditions. The discharge valve must not be opened, and any leaks must be promptly repaired to ensure safe operation. (5) Maintain the pressure in the second absorption stage within the specified process parameters. Adjust the opening degree of the gas pressure compensation valve from the first stage to the second stage as necessary to ensure stable operation. (6) When the explosion-proof plate of the scrubber leaks, it is possible to open the direct ammonia supply valve from ammonia cooler A to the scrubber, and close the inlet and outlet valves for ammonia to the scrubber, in order to maintain production temporarily. The explosion-proof plate should be replaced promptly to ensure safe operations. 6. Eliminate leaks in the system: (1) There should be no internal leakage in the discharge valves and safety valves of each section. Otherwise, the concentration in the ammonium carbonate solution tank must be increased, while the pressure of the gas should be kept at a low level. (2) The discharge valve and safety valve of the high-pressure ammonia pump must not leak. Otherwise, it will cause an increase in the load on the ammonia cooler system. (3) Regularly check for leaks in the system and address them promptly. 7. Optimize the urine evaporation and granulation system: (1) Ensure stable material transfer in each evaporation stage, prevent accumulation of liquid in the evaporators, and reduce the carryover of urea in the gas phase ； (2) The evaporation pressure and temperature in each stage must be kept stable to prevent issues caused by sudden changes in pressure and temperature. (3) The swirl plates in the two-stage evaporation separator should be cleaned regularly to avoid the accumulation of urea; otherwise, the formation of biuret over time can damage the equipment. (4) The temperature during two-stage evaporation should not be too high; it is sufficient for the moisture content to meet quality requirements; otherwise, it may cause problems during urine granulation. (5) The granulation nozzles should be replaced regularly, and the urine filters and nozzles should be cleaned. Prevent the granulation nozzles from becoming clogged, which could lead to problems such as abnormal operation of the equipment. (6) Maintain a stable rotation speed of the granulator to avoid sudden increases in speed that might cause urine to stick to the tower. 8. Extend the fault-free operation period of operating equipment: (1) Use high-quality equipment components, especially those for primary pumps, high-pressure ammonia pumps, and carbon dioxide compressors. (2) Improve the quality of maintenance to ensure long periods of fault-free operation. Because every time there is a system shutdown or stoppage, it causes damage to the system’s infrastructure, and it also hinders the proper functioning of various components within the system, leading to problems such as data loss and other issues./div> ::