Study On Ultrafiltration-Dynamic Magnetic Absorption Treatment Technology Of Kraft Black Liquor

The black liquor was treated by ultraflltration and dynamic magnetic absorption separation. Firstly, from the point of view of equipment and process, the influence of factors — design of plate, time, feed concentration, feed temperature and membrane pressure — on the process of ultrafiltration has been investigated. Studies on ultraflltration mass transfer characteristics and mechanism of black liquor are helpful in treatment of nonwood kraft black liquor. Secondly, the thesis was focused to explore the practicability of concentration by the use of ultrafiltration instead of multieffect evaporation, by the studies on desilicification, power consumption and combustion value of black liquor. Finally, the influence of factors on effectiveness of treatment of permeate liquor and absorption equilibrium has been investigated by using the technique of dynamic magnetic absorption separation. Study on the way of comprehensive utilization has also been done.The results show that:(1) The main inconsistent on black liquor treatment by using membrane technique is the inconsistent between the goodness of ultrafiltration and complexity of black liquor. It is of value in improvement of average flux rate to increase feed temperature, pressure and flow of feed bulk in some degree, or reduce the feed concentration. Incidentally, higher pressure and velocity may increase power consumption. The optimum operation conditions are 2% concentration of feed bulk, 0.23MPa membrane pressure , 1.22m³/h flow of feed bulk, and 50℃. The main factors affecting on COD_cr and BOD₅ removal is concentration of bulk, while membrane pressure and flow of feed bulk are the main factors affecting the power consumption. It has lower consumption operation adopting the formulation of cleaning agent, 0.1%EDTA+10%permeate.(2) Solute concentration on membrane surface (C_g) and mass transfer coefficient (k_m) can be used for characterization of mass transfer of ultraflltration. A pilot-scale plate-and-frame ultrafilter and two kinds of membrane were employed to treat the kraft black liquor. SPES-100 ( C_g=300.10g/l and K_m=17.27 × 10^-3m/h ) and SPK-100 (C_g=317.48g/l and K_m=24.96 × 10^-3m/h) differs each other. The SPK-100...