Basic Research On The Treatment Of Municipal Sludge With Hydrogen Production Technology Based On Chemical Looping

Sludge is a byproduct of sewage treatment and a complex heterogeneous mixture.China’s sludge production is large,so it is urgent to treat sludge.The sludge can be treated by thermochemistry to obtain pure energy hydrogen,which can be used in aerospace,automobile fuel and so on.Hydrogen is considered as one of the most promising energy sources in the future due to its advantages of clean and pollution free,high calorific value and wide sources.Chemical looping hydrogen production technology has the advantages of low energy consumption,low pollutant discharge and so on.Therefore,this paper uses chemical looping hydrogen production technology to treat sludge to carry out basic experimental research.Through mixing corn cob with sludge as the experimental fuel,the feasibility study of producing hydrogen by chemical looping using Cu-Fe bimetal oxygen carrier in a two-tower plate fixed bed reactor was carried out.The influence of the ratio of sludge to corn cob and the mass ratio of fuel to oxygen carrier on the effect of hydrogen production by chemical looping was investigated.The results showed that when the ratio of sludge to corn cob was 1:1 and the mass ratio of fuel to oxygen carrier was 1:7,a better hydrogen production effect could be achieved.XRD analysis shows that the oxygen carrier after the reaction has the formation of metal oxide in the low state,and no sintering phenomenon is found in the oxygen carrier after SEM characterization.The optimal reaction system was obtained by changing the reaction conditions such as water vapor content,carrier gas flow,fuel particle size,reaction temperature and mixing ratio of corn cob and sludge by using a single variable method:water vapor content of 38%,carrier gas flow of 200mL/min,fuel particle size of 0.075-0.125mm,reaction temperature of 900℃ and mass ratio of sludge and corn cob of 2:1.After ten cycles,the surface morphology of Cu-Fe oxygen carrier has no obvious sintering phenomenon,and its characteristics are relatively stable.During hydrogen production,carbon deposition affects the purity of hydrogen.The experiment shows that this is caused by tar produced by pyrolysis and gasification of samples in the reduction stage.After treating the oxygen carrier after reduction reaction at the experimental temperature of 900℃ and the inert atmosphere of Ar for 15 and 30 minutes respectively,the purity of hydrogen can be increased to 90.23%and 93.67%,which are 1.26 times and 1.31 times higher than those before treatment.The effects of tar on the reaction process can be reduced by using corn cob semi-coke instead of corn cob mixed with sludge.