Tianan Chemical Has Optimized The Sulfuric Acid Production Process With An Annual Output Of 800,000 Tons

This paper introduces sulfuric acid industry occupies an extremely important position in the national economy,especially in the application of chemical industry,known as the engine of chemical industry.Sulfur based sulfuric acid process has the advantages of simple process,less investment,low utility and power consumption,low environmental pollution,waste heat recovery and utilization,and good economic benefits.This paper takes the 800k T/a sulphur burning sulphuric acid plant of Yunnan Tian'an Chemical Co.,Ltd.was completed and put into operation in March 2005.The process adopts the processes of rapid sulfur melting,mechanical filter removal of impurities,mechanical atomization combustion,"3+1"two conversion and two absorption,four tower and two tank concentrated acid absorption.The total conversion rate and absorption rate of SO₂ are 99.83%and 99.95%respectively.Since the unit was put into operation,the production is stable,the energy consumption is low and the economic benefit is high.However,with the running time of the plant,adding sulfuric acid has the characteristics of strong corrosion.In recent years,a series of difficult problems have emerged gradually.Usually,the production load can only be maintained until the production load is reduced,and even sometimes the unit can only be shut down for maintenance,which seriously affects the stable operation of the unit,so technical transformation is urgently needed.Aiming at a series of problems arising from the 800 kt/a sulphur burning sulphuric acid plant,this paper systematically optimizes the transformation,absorption,tail gas washing and waste heat comprehensive utilization of the unit:1.The calculation results show that the process parameters of converter,including ventilation and catalyst loading,meet the requirements,and the equipment design parameters such as converter diameter,bearing area and allowable stress also meet the requirements.It shows that the converter can meet the requirements of the current national standard and can carry out the follow-up technical transformation.2.In view of the increase of resistance of drying tower in dry absorption system which seriously affects the production load,the original random packing in the drying tower was replaced with 125Y S-shaped ceramic corrugated structured packing,and the fiber mist eliminator of drying tower was replaced with wire mesh demister.The engineering verification shows that the resistance of drying tower has been reduced to an appropriate range,which can ensure the smooth operation of the device3.In view of the problem that the increase of drying acid temperature affects the production load,it is found that the main reason is that the water quality of circulating cooling water is affected,so it is necessary to strengthen the management of circulating water quality,adhere to the principle of adding chemicals according to the amount on time in each shift,and carry out cleaning,pre filming and normal treatment procedures for the circulating water quality according to the cycle.Through the treatment of water quality,the heat exchange effect is greatly improved,the acid temperature can be reduced to the index,and the production capacity of the unit is restored.4.In view of the problem that the acid mist at the outlet of the primary absorption tower exceeds the standard after the newly added low-temperature heat recovery device is put into operation,some control measures that are most suitable for the system are explored.(1)the inlet and outlet acid temperatures of the high-temperature absorption tower should be increased as much as possible,and the inlet air temperature should also be increased.(2)Strictly control the moisture at the outlet of drying tower.(3)The acid circulation system of the existing primary absorption tower was reformed to control the amount of acid absorbed in the secondary stage reasonably.(4)Try to improve the secondary absorption acidity.5.The optimization of tail gas washing device is implemented by increasing the height of defoamer layer,adding a water adding pipe and controlling the liquid level of absorption tower.The production practice after transformation has proved that the tail gas emission index of the device can be controlled within the national standard range.6.The technical and economic analysis of the thermal efficiency of the whole system is carried out.Through the optimization of sulfur based sulfuric acid process,the comprehensive energy consumption per unit product of sulfuric acid is reduced from-0.199tce/t to-0.217tce/t,which is reduced by 9.0%,and the unit production cost of sulfuric acid is reduced by 46.7419yuan,which has achieved good energy-saving and economic benefits.Through the systematic technical transformation and process optimization of the 800000 T/a sulphur burning sulphuric acid plant,the advantages of large-scale sulfur-based sulphuric acid plant can be brought into full play,and better meet the new requirements of the current industrial development.A feasible way is explored for energy saving,clean production and sustainable development of enterprises.