An investigation of reaction furnace temperatures and sulfur recovery

In a modern day sulfur recovery unit(SRU),hydrogen sulfide(H_(2)S)is converted to elemental sulfur using a modified Claus unit.A process simulator called TSWEET has been used to consider the Claus process.The effect of the H_(2)S concentration,the H_(2)S/CO_(2) ratio,the input airflow rate,the acid gasflow of the acid gas(AG)splitter and the temperature of the acid gas feed at three different oxygen concentrations(in the air input)on the main burner temperature have been studied.Also the effects of the tail gas ratio and the catalytic bed type on the sulfur recovery were studied.The bed temperatures were optimized in order to enhance the sulfur recovery for a given acid gas feed and air input.Initially when the fraction of AG splitterflow to the main burner was increased,the temperature of the main burner increased to a maximum but then decreased sharply when theflow fraction was further increased;this was true for all three concentrations of oxygen.However,if three other parameters(the concentration of H_(2)S,the ratio H_(2)S/CO_(2) and theflow rate of air)were increased,the temperature of the main burner increased monotonically.This increase had differ-ent slopes depending on the oxygen concentration in the input air.But,by increasing the temperature of the acid gas feed,the temperature of the main burner decreased.In general,the concentration of oxygen in the input air into the Claus unit had little effect on the temperature of the main burner(This is true for all parameters).The optimal catalytic bed temperature,tail gas ratio and type of catalytic bed were also determined and these conditions are a minimum temperature of 300°C,a ratio of 2.0 and a hydrolysing Claus bed.

CO_(2) and H_(2) selectivity properties of PDMS/PSf membrane prepared at different conditions

The effects of different solvent/water coagula-tion mediums,different coagulation bath temperatures(CBT)and different coagulants on the performance,morphology and thermal stability of polysulfone mem-branes were investigated.The CO_(2)/CH_(4),H_(2)/CH_(4) and H_(2)/N_(2) separation performance of the membranes were studied by gas permeation.Changing the N,N-dimethyl acetamide(DMAc)/water coagulation medium ratio from pure water to 90/10 vol%,resulted in a complete disappearance of the macrovoids throughout the polysulfone(PSf)polymeric matrix.The PSf membrane prepared in a CBT of 25℃ showed the best gas separation performance with ideal selectivities of 46.29,39.81 and 51.02 for H_(2)/CH_(4),CO_(2)/CH_(4) and H_(2)/N_(2) respectively,and permeances of 25 and 21.5 GPU for H_(2) and CO_(2) at 25℃ and 10 bar respectively.By increasing the amount of solvent in the gelation bath,the selectivities of H_(2)/CH_(4),CO_(2)/CH_(4) and H_(2)/N_(2) were dramatically reduced from 46.29,39.81 and 51.02 to 16.08,20.2 and 18.5 respectively at 25℃ and 10 bar.Reducing the CBT from 80℃ to 5℃ led to a complete elimination of macrovoids.Using methanol as a coagulant resulted in a less selective membrane compared with membranes from ethanol and water coagulants.The H_(2) and CO_(2) permeances were respectively about 3 and 9 times more than those for ethanol and water coagulants.Coated membranes were heated at different temperatures to investigate the suppression of undesirable CO_(2) plasticiza-tion.The membranes were stabilized against CO_(2) plasticization by a heat-treatment process.