疏水性单管陶瓷膜接触器在SO2吸收中的应用

Absorption of SO_2 by single hydrophobic ceramic tubule-based membrane contactor

对平均孔径200 nm的氧化锆陶瓷膜进行疏水改性与表征,并将其组装制成疏水性单管陶瓷膜接触器,采用清水作为低成本吸收液,开展了陶瓷膜接触器在废气脱硫方面应用的研究。比较了亲、疏水陶瓷膜接触器的传质性能,考察了进气流量、吸收液流量、进气浓度和吸收液温度等因素对SO_2脱除率和传质速率的影响,并对陶瓷膜接触器进行了长期稳定性测试。研究表明,疏水改性只改变陶瓷膜的表面性质(接触角达到132°),对形貌结构影响较小;与未改性的陶瓷膜相比具有更高的脱硫效率和总传质系数。SO_2的脱除率和传质速率随吸收液流量的增加均增加;SO_2的脱除率随进气流量和进气浓度的增加而降低,但传质速率增加;吸收液温度的升高不利于SO_2的吸收;原料气中的CO_2对SO_2的脱除率影响较小。与传统的填料塔相比,陶瓷膜接触器具有更小的传质单元高度(HTU)值。陶瓷膜接触器脱硫效率高,可稳定操作,在废气脱硫方面具有良好的应用前景。

The emission of SOx from marine vessels has caused serious environmental problem. Membrane contactor that offers several advantages over conventional tower device such as a compact size, operational flexibility, independent gas and liquid flow, easy scale-up, and modularity is an alternative technology in the application of marine exhaust gas desulfurization. In this work, a single ceramic tubule-based membrane contactor was fabricated from ZrO2 ceramic membrane with average pore size of 200 nm. A series of experiments of SO2 absorption were carried out using water as low-cost absorbent. The mass transfer performance of the unmodified and modified membrane was compared and the effects of gas flow rate, absorbent flow rate, feed gas concentration, temperature of absorbent on SO2 removal efficiency and mass transfer rate were investigated. The long-term stability of ceramic membrane contactor was tested as well. It was found that the overall structures and the surface porosity of ceramic membrane hardly changed by surface modification with hexadecyltrimethoxysilane （HDTMS）. The hydrophobic ceramic membrane with contact angle of 132° had higher desulfurization efficiency and overall mass transfer coefficient than those of the unmodified membrane under the same operating conditions. The desulfurization efficiency and mass transfer rate increased as the liquid flow rate increased. The desulfurization efficiency decreased as the gas flow rate and feed gas concentration increased while the mass transfer rate increased. Absorbent with low temperature was more favorable for the absorption of SO2. CO2 in the feed gas had little effect on the SO2 removal efficiency. The ceramic membrane contactor had lower height of transfer unit （HTU） value than conventional packed tower and showed great potential in the application of exhaust gas desulfurization.