Study On Solid-liquid Separation Characteristic Of The Fertile Liquor From Natrium-alkali FGD Technology

SO2 produced by smoke from burning coal and oil make air quality worse and acid rain more serious. The control of SO2 becomes an urgent demand. Due to the high capital cost and the lack of technology support, the study of desulfurization in China is left behind.The desulfurization cost will be hoped to be lower with the resource recycled by the natrium-alkali FGD technology whose fertile liquor recycled via ion-exchange membrane electrolysis. It mainly made up of dust-removing, washing-up, absorption, filtration and regeneration. As process of solid-liquid separation, filtration affected the regeneration rate and desulfurization efficiency. It's an important measure to prevent jamming of membrane. The characteristic of the suspension affected the separating method, operating parameter and separating efficiency directly. So in this paper, particle characters and filtration capability of actual absorption fertile liquor was studied by means of tests. Results were got as follow.There was greater difference between the solid consistency (2.2000g/cm3) and the liquid consistency (1.0764 g/cm3) of the suspension. The solid concentration is 1900 mg/L, and the average diameter of solid granule is 7.22μm, which led the sedimentation capability of suspension bad. Pressure filter was adopted to study on filtration characteristic of absorption fertile liquor in conditions of different filtration fabric (terylene240, terylene130 and terylene260) and pressures (0.04Mpa, 0.12Mpa and 0.2Mpa), initial filtration velocity and turbidity were also compared as well as regeneration capacity in this paper. The results show that the filtration velocity of terylene240 was moderate and the initial filtration turbidity was 12.6NTU with the regeneration capacity 93.58%, which was more suitable for the filtration.Through test analysis and theory derivation, we studied characteristic of the resistivity, void rate and compressibility of filter cake as well as influence of pressure in the course of the filtration. The resistivity of the filter cake was weak and the suspension was easy to be filtered. The resistivity of the filter cake increased and the void rate reduced a little when the pressure increased. The compressibility was slight. So the suspension was suitable to be separated by the filtration.The conclusion of this paper will play an important role in choice, design and optimization of filtration equipment for fertile liquor.