Technical Reformation Of Energy-saving And Emission Reduction For Alkali Absorption Section In Nitrate Production Process

Sodium nitrate,the traditional domestic sodium nitrite production process and liquid sodium nitrite and sodium nitrate with alkali solution absorption of nitric oxide in nitric acid plant exhaust,by evaporation,crystallization,sodium nitrite solution transformation processes of nitrite and sodium nitrate product,the production method of dilute nitric acid production process conditions and nitrate production limits,not mass production of nitrate products.The direct method of the construction project is the new technology developed in recent years,is not affected by the nitric acid production system,in the process of absorption of sodium nitrite and the liquid is relatively high,so the sodium nitrite products the proportion of high,low energy consumption,is the ideal method for the production of nitrate device for production capacity for larger.Device selection for ammonia oxidation after nitric oxide gas direct absorption process,and to take measures in the design,the production of adjustable sodium nitrite and sodium nitrate in a certain range of proportion.But with the national requirements of the construction of a conservation oriented enterprises,and large circulation,the consumption trend,this project has two problems:one is not high total solute content of semi-finished products in neutral solution,the average is about 370 g/L,evaporate steam consumption,the condensed water generated more,can not be used,causing water pollution;the two is the absorption of tail gas NOx emission concentration of about 2800 mg/m3,far greater than the national requirements of less than 300 mg/m3 index,caused certain pollution to the atmosphere.The technical transformation project mainly includes:first,increase 1#,2#base tower liquid storage capacity,reduce the tower liquid feeding frequency,ultimately reduce the low alkalinity circulation absorption time,ensure the semi-finished products nitrite ratio;two,lower alkalinity lean solution,from the original 65 g/L to 30 g/L,increasing two times caustic alkalinity from 120 g/L to 150 g/L,by increasing the total solute content two lye,eventually bringing the total solute content in neutral solution to above 430 g/L;three,through the transformation of the system,improve the quality of lye,reduce delivery time;four,change the column liquid feeding type and square type the alkalinity,the formation of a rising gradient from front to back,the tower absorption rate guarantee.Through the above transformation,two aspects to solve the problem of existence of alkali absorption.After the completion of the transformation,the post evaluation.The evaluation results show that operation,transformation device can make the neutralizing liquid(nitrate semi-finished products)in total solution quality by now 370g/L to 430g/L,the steam consumption is reduced from 600kg/t to 400kg/t from the previous;tail gas nitrogen oxide emissions in the 6#tower outlet by now reduced from 2800mg/m3 to 1500mg/m3 the following requirements.The catalytic reduction of 300mg/m3,reach the national emission standard.The energy saving effect is very obvious.Analyzed the existing problems,suggestions on gas distribution regulation test and lye quality test,further reducing the exhaust emissions of nitrogen oxide and enhance the total solute concentration and liquid.