Study On The Simultaneous Removal Of H₂S And CO₂ In High Gravity Reactors

With the increasing emphasis on the ecological environment,the demand for clean energy such as natural gas and biogas is increasing.However,most of the natural gas and biogas contain impurities such as hydrogen sulfide and carbon dioxide,which must be purified to meet the use requirements.Among them,the removal of acid gas(H2S,CO2)is the key step in the purification process.The national standards have clear requirements for the concentration of H2S and CO2 in the fuel gas.Hydrogen sulfide is highly toxic and will corrode the pipeline during transportation.Therefore,it must be deeply removed below 6 ppm.The presence of carbon dioxide will affect the heating value of the fuel.Therefore,the national standard requires the content of carbon dioxide to be below 3%.However,if the concentration of CO2 in the process gas is too low,it will affect the economic efficiency of the production enterprise.In order to take into account national standards and economic benefits,it is necessary to develop a more economical,energy-saving and controllable removal process.Compared with traditional equipment,high gravity equipment is small in volume and high in mass transfer efficiency,and it has high economic benefits in industry.To this end,this topic uses methyldiethanolamine(MDEA)as the main absorbent,piperazine(PZ)and diethylenetriamine(DETA)as additives,using water and organic solvents as solvents,respectively,in a rotating packed bed(RPB).A simultaneous removal experiment of H2S and CO2 was carried out,the effects of solvent type,high gravity level,liquid flow rate,temperature,and amine concentration on the absorption efficiencies of H2S and CO2 were investigated,and the best process conditions were obtained.A neural network model was established and optimized to predict the mass transfer coefficient and absorption efficiency of the system,and a preliminary study was conducted on the regeneration law of the MDEA/PZ system.The effects of regeneration time and cycle times on the absorption process were investigated.The main research results are as follows:(1)MDEA/PZ aqueous solution as absorbent:With the increase of high gravity level(?),liquid flow rate(L)and temperature(T),H2S and CO2 absorption efficiencies tend to level off after the first increase;When CMDEA is 1.68 mol/L,CPZ is 0.35 mol/L,L is 47.6 L/h,? is 122.5,the absorption efficiencies of H2S and CO2 can reach 99.98%and 96.51%,respectively,and the H2S and CO2 concentration in the treated gas are 2.51 ppm and 1.49%,respectively,to the requirements of GB/T 17820-2018.At the same time,the neural network model is used to predict The KGa and absorption rate within the RPB,and the error of the prediction results and experimental values is within 10%.(2)MDEA/DETA organic solvent as an absorbent:The results of solvent screening showed that when EG was used as solvent,the system had higher CO2 loading.The results of RPB absorption experiments show that with the increase of excess force level,temperature and liquid flow,H2S and CO2 absorption tend to be leveled after the first increase,and with the increase of CDETA/CMDEA ratio,the absorption efficiency of H2S decreases slightly and the CO2 absorption efficiency tends to be leveled after the first increase.When ? is 160,CMDEA is 1.01 mol/L,CDETA is 1.74 mol/L,L is 47.6 L/h,T is 333K,H2S and CO2 absorption efficiencies is 99.98%and 94.12%,respectively.The H2S and CO2 concentration in the treated gas were 1.41 ppm and 2.48%,respectively,to meet the requirements of the national standard for fuel gas.From the results of the study,with MDEA/DETA as the absorber and EG solution as the solvent,H2S and CO2 can be removed in the RPB reactor.