Optimization Of Sulfur Recovery Process In A Natural Gas Purification Plant Study On Sulfur Blowing Scheme

The H₂S content of sour gas in the process of sulfur recovery in a natural gas purification plant in Southwest Oil and Gas Field is reduced,and the original conventional Claus DC method and process parameters can not meet the field demand.The sulfur recovery rate in the sulfur recovery section is reduced and the energy consumption of the system is increased.At the same time,due to the lack of heat carrying air during the stable sulfur blowing process of the shutdown fuel gas,the sulfur blowing time is too long.Therefore,based on the field practice,HYSYS was used to establish the sulfur recovery process model.The effects of split feed position and split ratio on the temperature and reaction in the process equipment,the formation of by-products and the content of SO₂ and H₂S in the tail gas were systematically studied,and the feasibility of the split method was proved.On this basis,the effects of H₂S content in acid gas,split ratio,air-gas ratio,mixing ratio and outlet temperature of primary condenser on the operation of sulfur recovery process were analyzed.Subsequently,the above five factors were taken as the influencing factors,and the furnace temperature,sulfur yield and energy consumption were taken as the response values.The sensitivity analysis and the regression model of the response values were established.Finally,the optimization scheme of sulfur recovery process parameters was determined by the Design Expert software optimization module.The tail gas circulation was studied in the sulfur blowing stage of shutdown fuel gas.The influence of different cycle ratios on the gas volume and heat of the equipment and the mathematical equation of sulfur desorption rate and sulfur blowing gas volume were proved.The reasonable tail gas circulation ratio was selected,which provided theoretical guidance for the improvement of sulfur blowing scheme.The main conclusions are as follows:（1）In the feasibility study of the split method,it was found that the forward feed split operation is beneficial to the reduction reaction of sulfur in the sulfur recovery process,and reduces the formation of by-products and the content of SO₂ and H₂S in the tail gas,so as to improve the yield of sulfur,which is feasible.（2）The order of the significant influence of combustion furnace temperature is:split ratio>air ratio>acid gas H₂S content>mixing ratio=primary cooling temperature;the influence order of sulfur yield is:air ratio>acid H₂S content>split ratio>mixing ratio>primary cooling temperature.The influence order of energy consumption on aboriginality is:air ratio>acid gas H₂S content>split ratio>primary cooling temperature>mixing ratio.In the response surface analysis of energy consumption,it was found that the interaction between acid gas H₂S content and air-to-air ratio,split ratio and air-to-air ratio was extremely significant.（3）The optimization scheme of sulfur recovery process parameters:when the acid gas H₂S content was 29.81%,the split ratio was 0.329,the air-gas ratio was 0.642,the mixing ratio was 0.197,the primary cooling temperature was 170.238°C,and the combustion furnace temperature was 1098.5°C,the sulfur yield increased from 93.5%to 95.006%,increased by1.506%,and the energy consumption decreased from 11523 k W to 9836.734 k W,decreased by14.6%.According to the fluctuation range of acid gas H₂S content in each section,the suggestion of array optimization operation parameters is also recommended.In the absence of additional equipment,the sulfur recovery rate of sulfur recovery process is improved and the energy consumption is minimized.（4）In the stable sulfur blowing stage of shutdown fuel gas,it is found that the heat change of sulfur blowing gas is proportional to the change of gas volume.Combined with Wigner-Polanyi equation,langmuir isothermal equation and Bernoulli wind speed and pressure formula,the mathematical equations of desorption rate and sulfur blowing rate were established.Based on this,the increase of air volume and the decrease of time are analyzed,and the selection of cycle ratio is proposed.That is,the cycle ratio is 60%～70%,and the circulating air volume is 630.6 m³/h～735.4 m³/h.At this time,the stable sulfur blowing stage time of fuel gas will be reduced by about 13.15～16.73 hours,which provides theoretical guidance for the improvement of on-site sulfur blowing process.