Process Improvement Of 800kt/a Sulphuric Acid System

There has a 800kt/a sulfur acid production system in Hubei Sanning Chemical Industry Co.,Ltd which has been put into production in early2011.At the beginning of the operation of the acid production system,the sulfur content of the production material is high,the sulfur content is above99.5%,the impurities are few,the acidity is low,and the production of the whole sulfuric acid system is stable.However,due to market and other factors,sulfur prices continue to rise.The company takes measures to suit local conditions,and then uses powdered sulfur instead of granular sulfur as its raw material.It is characterized by low sulfur content and impurities.In the original process conditions,powdery sulfur can not meet the needs of production:first,lead to the production of sulfur smelting workshop confusion.The specific performance of the sulfur melting rate is slow,or even the amount of fine sulfur acid system can not meet the production load;filter clogging frequently,high labor intensity,and the filter NetEase damage;solid waste a large amount of cleaning,transportation and processing difficulties etc.The two is the result of fine sulfur sulfur melting section processed into sulphur furnace combustion ash is still up more than 0.005%?industry requires fine sulfur ash is less than or equal to 0.003%?.Enter into ash absorption system can cause blockage of acid system,seriously affected the long period,the stable operation of the system.Only 7 months after the use of powdered sulfur,the overall resistance of the acid production system rose rapidly,and at last it had to be overhauled ahead of schedule.Therefore,upgrading the quality of refined sulfur into the system has become a very difficult problem.After repeated consideration and verification,based on the original sulfur melting section not big adjustment,the investment of 1 million yuan,an increase of filter,and the filter is connected in series with the original,the original level of the filter into a two level filter.Through the headset after filtration,two filter outlet sampling analysis fine sulfur ash will decrease to about 0.001%.Although it can not fundamentally solve the problems of slow melting rate,light frequency and large amount of solid slag,it can effectively guarantee the long period stable operation of the system.Secondly,there is no tail gas washing device in the original sulfuric acid system,but with the increasing attention of the state to environmental protection.In order to achieve the new emission standards promulgated by the state,the company intends to add a set of lye tail gas washing device.The exhaust gas washing system invested about 1 million 700 thousand yuan,and fully automatic control.At the beginning of the system,30%Na OH solution was used as the detergent.After the operation of the tail washing system is stable,the sulfur content in the exhaust gas will be reduced from of the 900 mg/m³ at the two suction tower to 100 mg/m³,or even lower,which can meet the national emission requirements and effectively solve the environmental problems.At this point,and consider the process materials,NaOH procurement,transportation,consumption and other practical problems,then use the company made 10%dilute ammonia?pure ammonia measurement?instead of30%NaOH solution.After verification,using diluted ammonia water as detergent,the sulfur content of exhaust gas can still be kept below 100 mg/m³.The company has an annual output of 1 million 500 thousand tons of total ammonia production capacity by dilute ammonia can be exempted from purchase,transportation,storage and commodity alkali consumption and other issues,reduce the operation cost of the system,operating costs can be controlled at less than 1.5 million yuan.Moreover,the absorbed by-product?NH₄?₂SO₄ can be used as the raw material for the production of phosphoric acid or compound fertilizer,thereby further improving the economic benefit.