氨法烟气脱硫塔外氧化技术的模拟与优化

摘要

氨法脱硫塔外氧化技术是在传统的塔内直通空气氧化技术的基础上加以改进得到的一种新型技术.该技术将氧化环节移至塔外氧化器, 使得塔内气量减小, 出口烟气中氨逃逸量及气溶胶含量明显降低, 且结晶颗粒外观得到改善.使用Aspen plus软件对氨法脱硫塔外氧化技术全流程进行了严格的稳态模拟, 并对喷淋层分流比, 吸收液pH, 烟气温度, 浓缩段液气比等进行了重新优化设计.塔外氧化工艺最佳操作条件为:喷淋层分流比为0.7, 吸收液pH为6.1, 吸收段烟气温度为53℃, 浓缩段液气比为0.13左右.与传统的塔内直通空气氧化相比, 塔外氧化技术不仅可降低50％以上的氨逃逸, 而且控制方案要求较为简单, 操作方便, 更能适应日趋严格的环保要求.%Oxidation outside of tower is a new technique in ammonia-based fuel gas desulfurization system, improved from the technique of traditional direct air oxidation. It takes oxidation process to the oxygenizer outside the tower, reducing the gas flow rate in tower and the escape of ammonia in the exiting exhaust gas, and even improving the crystal grain appearance. Rigorous steady-state simulation was processed on the whole flow of the new technology by Aspen plus. Besides, splitting fraction of spray system, pH of absorbent, temperature of exhaust gas and the liquid-gas ratio of enrichment section were redesigned and optimized. The simulation results indicate that the best operation condition for the new process are as follows: splitting fraction of spray system is 0.7, pH of absorbent is 6.1, temperature of exhaust gas is 53 ℃ and liquid-gas ratio of enrichment section is 0.13. Compared with the traditional technology, the new technique can not only decrease the ammonia escape amount up to 50％, but also makes the control scheme demands and the operation more easy and convenient, so that it can accommodate the increasingly stringent environmental requirements.