Let’s discuss how urea can prevent leaks of liquid ammonia or methylamine

1. Strengthen equipment maintenance and management to ensure its safe operation； 2. Strengthen process management, strictly control process parameters, and ensure the long-term safe operation of the process system ； 3. Strengthen production management, improve production procedures, conduct thorough inspections, and identify and resolve issues promptly ； 4. Strengthen safety management and inspections, continuously identify potential hazards, and eliminate them.

The following suggestions are given on how to avoid leaks of liquid ammonia or methylamine: 1. The key is to properly design and select the materials for equipment, pipes, fittings, valves, etc., and to ensure their quality; this is the most important foundation. 2. Strengthen process operations to avoid overheating. Excessive temperature can lead to accelerated corrosion of equipment and pipelines, so it must be given serious attention. 3. It is necessary to try as much as possible to avoid overpressure incidents, as overpressure can cause destructive damage to equipment or pipelines. In particular, some sealing points are often weak points; once the pressure becomes too high and they can no longer withstand it, liquid ammonia or methylamine will leak from these areas. 4. Strengthen the corrosion prevention management of equipment. It is necessary to ensure an adequate supply of anti-corrosion air, and to prevent harmful substances such as chloride ions or sulfide ions from entering the urea system. 5. Operators must operate with care to avoid mistakes that could lead to overheating or overpressure, resulting in accidents such as leaks of liquid ammonia or methylamine.

I. Main Control Position 1. During operation, pay attention to controlling the action of the cycle pressure control valve to prevent sudden opening and closing; the control valve should remain in the closed state for extended periods of time. When operating the unit in its original mode, it is advisable to maintain a slight opening to prevent the accumulation of flammable explosive gases inside the inerting scrubber and ammonia cooler. 2. When the liquid level in the absorption tower is too high, it should be discharged slowly into the ammonium carbonate tank; rapid discharge is not allowed to prevent explosions or deformation of the ammonium carbonate tank. 3. The discharge pipelines of each device should remain unobstructed. 4. Before driving, check whether the stop valves under each safety valve are open. 5. When introducing steam, the pipes of the system equipment should first be preheated and any water accumulated in them removed, to prevent water hammer from damaging the equipment. 6. When introducing cooling water, first open the vent valve to the atmosphere and the drain valve to the ground; this allows air in the system to be released, thereby preventing water hammer. 7. When introducing ammonia, any water accumulated in the equipment and pipelines must be completely drained. 8. When using instrument air to fill and pressurize the system, the pressure of the instrument air must always be higher than that of the system, in order to prevent airflow from the system from flowing into the instrument air lines. Since the system contains ammonia, this could cause corrosion of the control system immediately, and water could block the air passages in the control system. There must be measures in place at the interface between the instrument air and the system to prevent leaks and to avoid any risks resulting from possible misoperations. 9. Pay attention to controlling the temperature of the ammonia condenser, as well as the gas composition and liquid phase temperature at the outlet of the scrubber; adjust the cooling water volume for the ammonia condenser and the scrubber in a timely manner to ensure that the composition of the exhaust gases remains outside the explosive range, and control the amount of air used for corrosion prevention. 10. Make sure to check whether the static electricity grounding device is in good condition; if it is damaged, it should be repaired promptly. 11. There must be no leaks at any of the sealing points in the exhaust system; if a leak occurs, it must be eliminated immediately. 12. Make sure to check that the lightning protection system is in good condition, conducting inspections once a year. 13. The vent pipe of the tail suction tower should not be vented directly; it should be connected to the main exhaust pipe, where it mixes with the steam emitted by the steam ejector before being vented. This is done to prevent the vent pipe from catching fire during thunderstorms, as a fire or backflow could lead to an explosion in the system. II. Evaporation Station 1. Strictly adhere to the process parameters for this station to prevent crystallization-related blockages; if such blockages occur or granulation is interrupted, they must be addressed promptly. During these repairs, care must be taken to avoid burns caused by steam and urine. 2. It is necessary to keep the circulation bypass line of the melt pump unobstructed, as well as the discharge valve at the pump inlet pipe unobstructed; when dealing with emergency situations (primarily to prevent crystallization and blockages in the system), it is essential to be able to drain material from these two locations or remove material from the system. 3. When stopping the operation, pour the urine from the tower into the urine collection tank, and then clean it with steam. It is strictly prohibited to use steam for cleaning without first pouring out the urine, as this can cause the urine to stick to the tower or the material basin. 4. Pay regular attention to the operation of the nozzles during operation, and adjust the speed appropriately according to changes in load. 5. It is not allowed to stick one’s head into the granulation tower while normal granulation is in progress, in order to avoid burns or injuries. 6. It is prohibited to cross the belt while it is in operation, to sit on it, or to place heavy objects on it. 7. Start the belt before granulation; in the event of a belt failure, granulation must be stopped immediately. 8. After parking, the ammonium formate and urine pipelines must be promptly diluted with water to prevent crystallization-induced blockages. 9. When introducing steam, the water accumulated in the pipes must be drained first to prevent liquid slugging. 10. When conducting inspections or maintenance at the top of the granulation tower, precautions must be taken to prevent falls from heights. When maintaining or replacing nozzles, the bolts must be tightened properly to avoid the nozzles falling off. 11. When removing urea that has adhered to the tower, the urea at the top of the tower should first be washed clean before it is introduced into the tower. When cleaning at the bottom of the tower, a safety helmet must be worn and a safety net installed, with cleaning being carried out from top to bottom. It is not allowed to clean the nozzles or test them at the top of the tower. III. Pump Room Duties 1. The packing of liquid ammonia pumps, primary methane pumps, and secondary methane pumps requires regular maintenance and inspection to prevent leaks, spills, and other losses that could contaminate the environment. 2. When pressurizing the bypass lines for liquid ammonia pumps, monoethylamine pumps, diethylamine pumps, and high-pressure flushing water pumps, if the pressure does not increase even though the bypass valves are closed, these valves should be opened immediately. It is strictly prohibited to start the pumps with both the outlet valves and the bypass valves closed or blocked. 3. The pressure fluctuation range of the liquid ammonia pump, monoethylamine pump, and diethylamine pump should be small; the bottom valve of the pressure gauge should be adjusted to a lower setting in order to minimize fluctuations in the pressure gauge needle, but it must not be closed completely. 4. After the pump trips, a thorough inspection of the pump body, electrical components, instruments, oil pressure, etc. should be carried out; it can only be restarted once no issues are detected. 5. Operators should regularly check the current fluctuations of the pump in order to determine whether it is operating properly. 6. The high-pressure bolts used in liquid ammonia pumps and methylamine pumps should be regularly inspected for visual defects and subjected to periodic non-destructive testing; if any problems are detected during use, they should be replaced promptly. 7. After the pump is started normally, the discharge valve of the liquid ammonia buffer filter should be closed promptly to prevent accidents caused by the excessive release of gaseous and liquid ammonia. 8. If there is a large amount of liquid ammonia leakage, this position is not capable of handling it; the control room can shut down the ball valve or emergency cut-off valve located beneath the buffer tank on the third floor. 9. The pressure gauge and ball valve of the No. 1 pump are prone to clogging; it is necessary to check them when starting or stopping the pump to ensure unobstructed flow. 10. During short-term parking, the three material pipes of the synthesis tower should be flushed every 4 hours, and the discharge pipe of the synthesis tower should be flushed every 8 hours.