Design Of Digested Slurry Purification Device With Biomass Ash As Filter Material

In the existing methods of disposal of livestock and poultry dung,Biogas engineering has been widely used in various livestock farms due to its advantages such as heavy load/good purification effect and changing waste into treasure.However,how to deal with a large number of digested slurry in the operation of biogas projects has attracted much attention.Biomass ash is the residue produced after straw power generation in biomass power plant,It has loose porous structure and good adsorption performance.And the research has shown that,biomass ash can effectively remove impurities such as COD and TS in digested slurry.Therefore,this study is based on the adsorption properties of ash,a digested slurry purification device with biomass ash as filter material has been independently designed,including the overall structure design and components selection.Experiments on the resistance of biomass ash to digested slurry flow showed that:Under certain height ratio and flow condition,the resistance of biomass ash to digested slurry is related to its distance.The unit distance pressure drop is 0.112 MPa.Digested slurry purification device adopts tank structure design,mainly composed of cylinder,upper cone,lower cone and other components.The lower inlet design was adopted to improve the contact adsorption ability of digested slurry and ash.The diameter of the monomer tank is 530 mm,the height is 1500 mm,the upper cone is 115 mm,the taper is 45°,the lower cone is 164 mm,and the taper is 45°.The volume of the monomer tank is 0.42 m3,the effective ash filling height is 1.2m,and the effective purification chamber volume is0.29m3.In order to avoid the inconvenience of processing,transportation and loading,the height of the monomer tank is too large,Under the condition of ensuring the flow of digested slurry through the path,a 3 level 4 tank operation mode is adopted.3 levels and 4 tanks of the purification device are connected through pipes.The valve is used to control the flow direction of the digested slurry,during operation,3 stages are achieved through valve control to improve the purification effect.At the same time,another purification tank is in the unloading and loading process.During the operation of the plant,the final stage of purification is guaranteed to be filled with new slag.The operation test of the digested slurry purifying device shows that: after the treatment of digested slurry by biomass ash,the color gradually clarified as the process increased.The removal efficiency of COD increased with the increase of distance.The parameters of digested slurry varied with different distance along the distance(0.35 m,0.65 m,0.95 m,1.55 m,1.85 m,2.15m),COD is 1679mg/L,1598 mg/L,1428mg/L,1235mg/L,1208mg/L and 1166mg/L.The TS of the filtrated digested slurry decreased with the increase of the distance along the distance,the maximum removal rate of COD is 44.3%;TS is 6.47 mg/L,5.45mg/L,5.76mg/L,2.87mg/L,1.49mg/L and 1.37 mg/L respectively,the maximum removal rate of TS is 92.5%;the p H of filtered digested slurry increased with the increase of distance.p H is 9.02,9.12,9.16,9.98,10.15 and 10.5 respectively.In addition,the influence of running time on the purification efficiency of digested slurry was studied.The results showed that COD increased with the increase of running time,that is,the purification effect is weakened.Different running time(0.5h,1.5h,2.5h,3.5h,4.5h)has different effects on the parameters of digested slurry after filtration.The changes of COD in the digested slurry after filtration is 1235 mg/L,1378 mg/L,1417 mg/L,1509mg/L and 1585mg/L respectively;TS of the digested slurry after filtration changed with time,TS is 0.92 mg/L,4.2 mg/L,2.63 mg/L,3.93 mg/L,4 mg/L respectively.p H is 9.11,9.21,9.18,9.13 and 8.94 in turn.It also shows irregular changes,which need further study.