| Electroplating sludge mainly comes from the solid waste produced in the process of electroplating wastewater treatment.It has high moisture content and great harm,so it must be safely treated.Belt drying process to effectively reduce the amount of sludge is the main way of harmless and resource treatment of wet sludge.However,dust is inevitable in the process of belt drying,which not only affects the safety and stability of sludge drying equipment,but also seriously endangers the life and health of the surrounding environment and workers.In this thesis,combined with the sludge belt drying process and the characteristics and application status of filter dust removal technology,the filtration and dust removal technology of the wet sludge layer was proposed.Taking the wet sludge layer filter material and the dust produced in the drying process as the research object,the water content,bulk density and porosity of electroplating sludge,the shape,dispersion,density and wettability of the dust are studied,which reveals the mechanism of the wet sludge layer filtration dust.The multi-layer belt low-temperature drying equipment developed and designed by the project team was applied to the sludge treatment process transformation project,and dust concentration and filtration efficiency of the first layer of wet sludge layer were measured under different water content,tiling thickness,filtration wind speed and supply air temperature,so that the dust concentration at the lower side of the wet sludge layer decreases with the increase of water content and tiling thickness,and increases with the increase of filtration wind speed.The variation range is 18mg/m~3 to 36mg/m~3.The filtration wind speed and the tiling thickness of wet sludge layer have great influence on the filtration efficiency of dusty air flow,while the change of supply air temperature has no obvious effect on the filtration efficiency of dusty air flow.They are beneficial to improve the filtration efficiency by reducing the filtration wind speed and increasing the tiling thickness of wet sludge layer.The highest filtration efficiency of wet sludge layer is 74%in this experimental range.The changes of filtration efficiency and pressure drop before and after filtration were studied by single factor analysis of moisture content of wet sludge layer,apparent filtration wind speed,tiling thickness,inlet dust concentration and filtration time.The test not be completed in field was supplemented.The results showed that increasing the moisture content of the wet sludge was beneficial to the adsorption of dust.When the filtration wind speed reached 1.2m/s,the wet sludge layer appeared fluidization state,which led to a sharp decline in filtration efficiency and no change in pressure drop.The dust filtration efficiency decreases sharply with the extension of the filtration time.When the filtration time is more than 15min,the filtration efficiency and filtration pressure drop remain unchanged at 41.7%and 172Pa respectively.By orthogonal experimental design,it was found that the main factors of filtration efficiency and pressure drop of wet sludge layer are tiling thickness and filtering wind speed.The optimal conditions to meet the actual site engineering are 65%moisture content of wet mud into mud,30mm tiling thickness of the first layer of mesh with wet sludge,1.1m/s filtering wind speed,and 1900mg/m~3 dust concentration at the inlet.In this thesis,a mass of field tests and experimental studies have been done on the filtration and dedusting technology of the first layer of the net belt wet sludge layer in the sludge belt drying process,which provides reference for the operation parameters of the sludge belt drying equipment and the dedusting design of the oven. |
