高倍率灰钙循环脱硫过程及影响因素研究

为深入了解神东30 t/h煤粉工业锅炉对应的高倍率灰钙循环脱硫除尘一体化技术(NGD,no gap desulphurization)脱硫过程及机理,研究不同影响因素对脱硫效率的影响。笔者在反应器上沿程打孔取样,检测不同位置脱硫剂硫含量和水分变化,结果发现,随着脱硫反应的进行,脱硫剂中水分和硫含量分别呈降低和增加的趋势,说明水分对脱硫反应至关重要,在有水存在的条件下,脱硫反应从气固两相反应变为离子间的液相反应,脱硫反应速率显著增加。随着脱硫反应的进行,脱硫剂中反应产物增加导致硫含量增加。检测反应器沿程烟气中成分及含量变化,根据反应器上单位距离脱硫效率的变化率,将脱硫过程分为3个阶段:常速段、降速段、拟平衡段,前2个阶段脱硫反应速率快,为脱硫反应的关键段,所脱除的SO_2占SO_2总量的90%,因此强化前2个脱硫阶段是提高脱硫效率的有效手段。最后,在NGD脱硫装置上进行工程试验,研究增湿水量、SO_2初始浓度、掺混比对脱硫效率的影响规律,结果表明,增湿水量增加,SO2初始浓度降低,熟石灰占比增加,相当于脱硫反应物初始浓度增加,促进脱硫反应向右进行,初始阶段脱硫反应速率增加,因此最终脱硫效率呈现增加的趋势。但由于脱硫剂孔隙结构及活性物质含量的限制,脱硫反应存在最佳的工艺条件使脱硫剂中有效物质被充分利用,根据脱硫效率的变化量最终确定增湿水量、SO_2初始浓度、掺混比最佳范围,分别为0.14～0.27 t/h、350～550μL/L、3∶1～2∶1,此时脱硫效率的变化量分别为28.81%、25.87%、10.55%。 Based on the circulating desulfurization with high ratio of ash and calcium( No Gap Desulphurization) of Shendong 30 t/h coalfired industrial boiler,and in order to further find the desulfurization process and mechanism,the influence of different factors on the desulfurization efficiency was studied.In this paper,the sulfur content and water content of desulfurizer in different positions were detected by drilling and sampling along the reactor firstly.The results show that the water content and sulfur content in desulfurizer decrease and increase respectively with the desulfurizing reaction,which indicate that water is very important for desulfurizing reaction.In the presence of water,the desulfurizing reaction changes from gas-solid two-phase reaction to liquid-phase reaction between ions,and the desulfurization reaction rate increases significantly.At the same time,with the desulfurization reaction,the reaction products in the desulfurizer increase,so the sulfur content increases. Secondly,the change of composition and content of flue gas along the reactor is detected. According to the change rate of desulfurization efficiency per unit distance on the reactor,the desulfurization process is divided into three stages: constant speed section,deceleration section and quasi balance section.The desulfurization reaction rate of first two stages is fast,which is the key section of desulfurization reaction.The SO_2 removed accounts for 90% of the total SO_2. Therefore,It is a effective method to improve the desulfurization efficiency by strengthening the first two desulfurization stages.Finally,the engineering test was carried out on the NGD desulfurization unit to study the influence of the humidification water quantity,initial concentration of SO_2 and the mixing ratio on the desulfurization efficiency.Finally,the results are as follows: the humidification water quantity increases,the initial