Weekly Topics on Synthetic Ammonia Handling Abnormal Operating Conditions
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This post was last edited by TH373637 on 2011-9-13 17:00. How should a fire accident at a synthesis facility be handled? Answer based on practical operations, with separate handling according to the time taken to deal with the fire ； Everyone participated actively and discussed this abnormal operation. Dear sea friends, please do not reply secretly. Reference answer: 1. Quickly determine the location of the fire and its intensity, and promptly isolate the area where the fire is occurring; if isolation is not possible, immediately inform the control room and relevant personnel to initiate an emergency shutdown ； 2. Strictly prevent high voltage in the system from leaking into low voltage, ensure system safety, and prevent accidents from escalating ； 3. Release pressure from the compressor ； Venting behind the tower, synthetic protection catalyst (to control the venting rate and direction; secondary ignition or explosion must be prevented at all costs) ； 4. Stop the moving equipment; it is strictly prohibited to start such equipment, or notify the electrician to shut it down in the power distribution room ； 5. Use the fire extinguishing equipment available at this post to prevent NH3 poisoning ； 6. Report to the workshop and relevant personnel as well; in an emergency, it is perfectly acceptable to handle the matter first and report later, as the optimal time for taking action must not be missed ； 7. The synthesis system shall undergo short-term or long-term shutdowns depending on the fire situation, in order to carry out full or partial system replacement and nitrogen purging for protection ； 8. Handle the situation calmly; it is strictly prohibited to allow a second fire or explosion to occur as a result of dealing with the accident. This ensures that all combustible gases in the system are completely burned up, as high pressure makes it extremely difficult and dangerous to extinguish fires caused by gases.
This post was last edited by Chemical Gas Purification on 2013-1-4 at 09:14. 1. In the early stages of a fire, when the flames are small, cover them with a wet cloth to cut off the air supply, thereby extinguishing the fire. 2. In the event of a larger fire, it is necessary to close the valves connected to that area, shut down the equipment, and use a 3.5-kilogram fire extinguisher to put out the fire. 3. In case of a large fire, stop the machine immediately and use fire trucks to extinguish the fire.
Decide whether to stop based on the size of the flame. If the fire is small, use N2 or LS to extinguish it; if the fire is large, check whether it is possible to isolate that section in order to put out the fire, otherwise stop the machine immediately, relieve pressure to a slightly positive level, and then use N2 or LS to extinguish the fire. After extinguishing the fire, the leak points must be addressed immediately. For areas with minor leaks, an N2 purge port can be used to continuously blow N2 in; for areas with larger leaks, it is necessary to consider replacing the gasket or adding a second valve.
How effective is using steam to extinguish fires?
In the event of a fire in the synthesis system, the following actions should be taken: First, upon discovery, depending on the size of the fire, if it is small, extinguish it directly using a fire extinguisher, and contact the workshop or dispatch team to check for leaks； 2. When the fire is severe, it is recommended not to handle it alone; instead, notify the relevant authorities and then identify the cause of the fire at the production site before cutting off the gas supply. Generally, it may be necessary to stop the operation of the equipment in such situations. It should also be noted that when cutting off the gas supply, it is not allowed to create a vacuum in the tower or container, as this could pose an explosion risk; the approach to handling this varies depending on the specific circumstances ； 3. In the past, fires have occurred in our plant’s synthesis tower vents, and steam has proven to be an effective method for extinguishing such fires. In short, safety first!
First, locate the point of ignition and inform the dispatch team, unit supervisors, and the company’s fire brigade. In the early stages of a fire, use carbon dioxide cylinders or dry powder extinguishers to put out the fire. If it cannot be extinguished, the gas supply should be cut off, and pressure should be relieved by venting from behind the tower to reduce the pressure inside it; simultaneously, carbon dioxide fire extinguishing agent should be used to put out the fire. After extinguishing the fire, proceed with parking. If the fire still cannot be extinguished or brought under control, and there is a risk of it spreading, proceed with an emergency shutdown. When releasing pressure to vent, the pressure release point should be kept away from the ignition point to prevent the fire from spreading
When the fire is small, N2 can be used to extinguish it. If the fire is larger, contact the control room to carry out pressure reduction operations; if the fire is reduced as a result of this, attempt to put out the fire using a fire extinguisher or N2, and then seal the leak while the system is still under pressure. If lowering the pressure still fails to extinguish the fire, there is no time to hesitate – an emergency shutdown must be carried out to prevent the fire from spreading and causing catastrophic accidents.
If the top of the tower is on fire, the reason is: 1. Gas leakage from the top of the tower burns when it comes into contact with air. 2. Excessive airflow velocity leading to static electricity sparks that cause ignition. 3. When the electric furnace is started, there are leakage points, and the gas is ignited by the furnace wire electrode rod. 4. During maintenance, when the high-temperature part was removed, it caught fire due to leaking gas. 5. The leaked gas, carrying catalyst powder, oxidizes and ignites the gas, causing a fire. Handling: In the event of a fire, the furnace should be powered off first, after which CO2 or dry powder fire extinguishers should be used to put out the fire (note that foam fire extinguishers must not be used as they conduct electricity). If the fire cannot be extinguished, the tower should be opened immediately to reduce the pressure inside it, while continuing to use CO2 fire extinguishers. If there is a leak between the top cover and the tank flanges, steam should be used to extinguish the fire after the pressure has been reduced; repairs can then be carried out after the fire is extinguished. If the fire cannot be extinguished or controlled, and there is a risk of it spreading, emergency pressure relief and shutdown procedures should be followed. Pressure relief must not be carried out at the current workstation; it should be done in a location away from the site.
Run fast and leave the fire extinguishing to the college students
Fires in synthesis units are mostly caused by high-pressure gases leaking at welds or flange leaks at high speeds, which generate static electricity sparks. Also, during the maintenance work, proper isolation from ignition sources was not ensured, which caused some minor leaks that are usually difficult to detect to catch fire. In the case of the latter, as long as it is detected in time, the fire can be extinguished using a dry powder fire extinguisher or by introducing inert gases such as steam or nitrogen. But in the former case, it depends on the circumstances: first, if the fire is intense, it indicates a large amount of leakage; immediate contact should be made with the dispatch system to summon firefighters, and the system’s load should be reduced. The pressure involved in the synthesis process should also be lowered at the appropriate time to reduce the amount of leakage. Under no circumstances should the fire be allowed to spread or burn for too long. The surface temperature of the equipment itself at the point of ignition will be very high, making it easy for the flames to reignite. If the burning time is prolonged, be sure not to use a water jet, as this will damage the equipment and cause the leak to worsen. The load should be significantly reduced until production is halted. If the flame is extinguished midway, it is essential to continue cooling the surface of the leak site to prevent it from reigniting. At this time, attention must be paid to ventilation at the site for safety reasons; if necessary, forced convection should be employed to prevent poisoning of personnel and accidents such as explosions.