Treatment process of tail gas of metal heat treatment nitriding furnace
Date of release:2018-05-18 Author: Click:
Absorption in a sulfuric acid solution. Sulphuric acid is used to absorb ammonia to produce ammonia sulphate. Ammonia sulphate is an important fertilizer, and ammonia gas is absorbed again to achieve environmental protection, and the by-products can be reinvested. However, for enterprises, buying sulphuric acid is a difficult problem, and sulfuric acid is also a great consumption.
Nitrogen oxide (NO) has a strong affinity for human hemoglobin. It can squeeze oxygen out of the human blood and exposure to nitrogen oxides for a long time. When the concentration exceeds 1.5mg/m3, people can cause cancer. A large number of nitrogen oxides will also cause photochemical pollution and cause great harm to organisms. In addition, it can also cause acid rain and destroy the ozone layer. The harm is higher than the ammonia. The requirement for ammonia in the national standard is much lower than that for nitrogen oxides.
The ammonia oven uses ammonia water to absorb water, and the concentrated ammonia water is separated from the distillation tower by distillation tower, then condenses and pressurized, and then is stored and reused with ammonia storage tank. This method is evolved from the ammonia synthesis process, which can not only ensure the maximum utilization rate of ammonia, but also eliminate the excessive emission of ammonia. However, there are many problems such as high cost of equipment input, high operation cost, uneconomical and potential safety hazard.
Metal nitriding refers to a chemical heat treatment process that causes nitrogen atoms to infiltrate into the surface of the workpiece under certain temperature. Nitriding products have excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance. At present, nitriding furnace is the main technology of metal nitriding in China. The ammonia is passed into the nitriding furnace. Under the condition of high temperature and anoxia, ammonia is decomposed into nitrogen and hydrogen, and hydrogen is discharged directly, and nitrogen goes deep into the metal to be processed. Ammonia decomposition rate is generally between 15%-30%, a large number of non used ammonia gas directly discharged, ammonia gas is a strong irritating odor of colorless gas, belongs to low toxicity, mainly on the upper respiratory tract and corrosion. When the concentration of ammonia is up to 1750mg/m3, life can be endanger.