In China's food refrigeration system, more than 80% of the cold storage using ammonia as refrigerant, with the development of science and technology, the establishment and improvement of various standards and systems, the safety of food cold storage requirements are more and more stringent, and the safety of food cold storage ammonia refrigeration system has become a key issue of cold storage engineering. In order to prevent and reduce the harm of ammonia leakage and protect personal and property safety, more attention is paid to how to design the ammonia leakage automatic alarm system in the cold storage design, so as to ensure the operation safety of the ammonia refrigeration room.
NH3 leakage is a special hidden risk in ammonia cold storage. In the event of an ammonia leak, the first thing to happen is a fire. When the ammonia concentration reaches 15.5% to 27%, an open flame will cause an explosion. Because ammonia itself is toxic and harmful to the human body, ammonia leakage can also cause convulsions, fainting, and even suffocation.
There are many reasons for ammonia leakage in cold storage, including the aging of equipment, personnel's operation errors, and negligence of management. With the growth of service life, the equipment will have different degrees of aging. Valve aging, the axis is loose, making the air tightness decreased, resulting in ammonia leakage. The welding place of the pipeline in the cold storage may also be aging, producing cracks, or the pipeline is corroded and the flange is aging, resulting in leakage.
Staff violations. Causing an ammonia leak. Improper operation of workers, liquid ammonia or equipment oil into the compressor cylinder, causing excessive pressure in the cylinder, the top of the cylinder head to open the leakage accident. The workers stacked the goods when the stacking is not strong, after the goods froze and hardened, the sudden collapse caused by the evaporation pipe rupture, gas leakage. During loading and unloading, the forklift was working in the cold storage room and accidentally scooped the evaporation pipe on the wall, resulting in leakage. During the normal operation of the compressor, if the worker mistakenly closes the valve in the section from the compressor to the condenser, this section of the pipeline may burst, causing leakage.
1.Solution:
Monitoring location: cold storage liquid ammonia storage tank area, refrigeration equipment assembly workshop, loading and unloading site, ammonia gas transmission pipeline
2.Monitoring gas: Ammonia
Data transfer: According to the actual situation of the cold storage site, ammonia detection and alarm devices should be installed in each monitoring position. In case of ammonia leakage, the detected ammonia concentration data should be transmitted to the controller in the form of current signal or wireless transmission at the first time, and the gas cut-off valve should be connected to quickly cut off the source of gas transmission, start the on-site exhaust system, and quickly eliminate toxic gas. Ensure the safe operation of site personnel and the normal operation of equipment.