Experimental Study On Reduced Pressure Membrane Distillation Concentration Processing Doctor Solution

HPF desulfurization process is a catalysis, oxidation,desulfuration and dehydrogenization precess in which ammonium is the alkali source and HPF acts as the catalyst . The desulfurizing liquid generated in the process include ammonium thiocyanate , ammonium thiosulfate, etc. when the amount of dissolved solids in desulfurizing liquid is more than 250g/L, the desulfurizing system can not work in a normal way. Now, the amount of dissolution solid in desulfurizing liquid in desulfuration and dehydrogenization of coking plant in Chong Qing steel and iron company limited is more than 350g/L,the plant needs to discharge 30 ton to reduce the desulfurizing liquid concentration in the system and main the efficiency of desulfuration and dehydrogenization. The discharge of desulfurizing liquid causes great harm to the environment because of its high concentration, strong corrison. Therefore, it is urgent to find a plausible and economic way to treat desulfurizing liquid to decrease the solid amount in desulfurizing liquid , improving the desulfurizing efficiency.This paper makes a detailed analysis of the components of desulfurizing liquid, proposes an experiemental decompressing membrane distillation concentration + evaporation crystallization way to treat the desulfurizing liquid and makes a experimental study of desulfurizing liquid after decompressing membrane distillation concentration treatment. The experiment makes use of PVDF hollow fiber membrane module with inside diameter of 1.0mm,wall thickness of 0.1mm,the porosity of 85%,pore diameter of 0.15μm,and length of 20cm to concentrate the ammonium thiocyanate , ammonium thiosulfate and desulfurizing liquid and then explore the influence of operating condition and component loading density on the performance of decompressing membrane distillation.The experiment shows that the membrane flux increases along with the increase of the temperature of the thermal side material liqid and the increase of the gradation of cold side vacuum in the process of decompressing membrane distillation. The influence of the increased speed of thermal side material liquid on membrane flux in VMD process is not obvious. When the membrane wires in decompressing membrane components increase, the generation of water in components is increases and thus a maximum of water generation in a single membrane component appears. The variance of orthogonal test shows that cold side vacuum and membrane loading component density are the main factors that influence the membrane flux in the VMD process, and the temperature, density and flow speed are the secondary factors. When the density of membrane loading component is 10.20%,the flow speed and temperature of thermal side material is 0.36m/S and 65°C respectively. Besides, the vacuum of cold side is 0.095MPa, membrane flux is 9.94( Kg / m2?h)and the water generation is 4.00( Kg / m2?h). The ammonium thiocyanate in the liquid is 600g/L, which is the optimal concentration endpoint. The retention rate mains more than 99.5% and the amount of distillate solutes is not affected by the density of the loading components ans operating condion in the whole process.The experiment aims to design a systematical plan of decompressing membrane distillation and evaporation crystal concentration technique in daily disposing thirty tons (1.5 m 3 /h)of desulfurizing liquid for coking plant in Chong Qing Steal and Iron Company Limited.