CO置换的SO2/NOx同步反向解耦及协同脱除机制

The removal of both SO2 and NOx could be achieved by decoupled adsorption-regeneration process. In this process, oxygen could promote adsorption and inhibit reduction. CO could reduce NO and enhance NOx desorption and catalyst regeneration. The enhancement of desorption by CO also works for SO2 adsorption process. SO2 in the flue gas could poison the NOx catalysts and thus contact between SO2 and NOx catalysts should be avoided. In this application, we propose a novel process, synchronous SO2/NOx decoupling promoted by CO. This process is designed in a rotary reactor with an adsorption zone running flue gas and a desorption zone running reducing gas CO. Flue gas and reducing gas CO flows conversely. The SO2 adsorbents are located upper to the NOx catalysts. Thus flue gas adsorbs SO2 and NOx sequentially. Then CO desorbs NOx and SO2 sequentially. In this process, SO2 and NOx are simultaneously removed by the synchronous decoupling. The desorption and regeneration step could be significantly promoted by reducing gas CO. The contraflow of flue gas and CO could avoid the contact of SO2 and NOx catalysts and thus avoid the catalyst poisoning. In this project, we propose to study the dynamic process of synchronous decoupling of SO2/NOx removal, analyzing the promoting effect of CO during desorption. The mechanism of SO2/NOx synchronous decoupling and CO replacing effect will be developed. This research will help to develop novel technologies of simultaneous SO2/NOx removal.

烟气中的SO2/NOx脱除可通过吸附-再生解耦过程实现，各反应的主要影响因素为：氧气可促进SO2/NOx吸附，抑制NOx还原；CO可还原NOx，同时可促进NOx和SO2脱附；SO2易造成脱硝催化剂中毒。针对此特点，本申请提出了一种CO置换的SO2/NOx同步反向解耦过程：在回转式反应器中设置流通烟气的吸附区和流通CO的再生区，烟气和CO反向流动，SO2吸附剂和NOx催化剂分别位于上下层；烟气依次经历SO2和NOx吸附，CO依次经历NOx还原脱附和SO2脱附。此过程实现了SO2和NOx的同步解耦脱除，充分利用了CO对脱附和再生的促进作用，反应流向的设置也避免了催化剂硫中毒。本申请拟研究SO2和NOx同步脱除的吸附再生解耦动态，剖析CO在脱附和还原过程中的置换作用，阐释其快速深度再生机理，建立SO2/NOx同步反向解耦过程及CO置换再生机制，为SO2/NOx同步解耦脱除技术提供理论基础。

本研究选取商业半焦作为催化剂载体，制备了附载铁钴的活性半焦催化剂，并研究了不同氧气浓度、吸附还原时间比、反应器空速以及还原区空速对催化剂吸附还原动态脱硝的影响，同时探究了H2O、SO2和CO2等气氛对催化剂脱硝性能的影响。本研究还选取商业半焦并进行改性优化，来探究其在回转式反应器中的脱硫特性，考察了半焦吸附剂及其活化改性半焦吸附剂在100℃-300℃内的脱硫性能，通过实验对比得到了几种效果有明显提升的改性半焦吸附剂，并且研究了不同工况对回转式反应器动态脱硫过程的影响。此研究与技术可用于燃煤电站锅炉的脱硫脱硝烟气处理，同时此技术在冶金、焦化、钢铁行业的市场需求更强烈，因为此类系统的烟气温度较低且波动大，传统的氨法SCR效率不高且不稳定，而本研究提出的回转式脱硫脱硝反应器内首先由NOx吸附实现脱硝，温度越低吸附效果越好，故低温和温度波动下脱硝效率稳定。还原剂的运行成本方面，由于冶金、焦化和钢铁企业一般拥有制焦煤气或高炉煤气等燃料或副产品，可直接作为CO脱硝的还原剂，故运行成本非常低。即使在电站等不配备煤气的企业，也可采用煤气化或购买合成气，简单便捷。故回转式脱硫脱硝同步解耦技术在电站、冶金、焦化、钢铁行业均有强烈的市场需求，投资和运行成本均较低，有很好的产业化前景。