Wet flue gas desulfurization performance of 330 MW coal-fired power unit based on computational fluid dynamics region identification of flow pattern and transfer process

Wet Flue Gas Desulfurization(WFGD)unit based upon spray scrubber has beenwidely employed to control SO_(2) emissions from flue gas in coal-fired power plant.To clarify the dependence of desulfurization performance on inter-phase transfer behaviors with non-ideal contacting patterns of flue gas and slurry droplets,three regions in spray scrubber are distinguished in terms of gas-slurry flow structures using CFD method in the Eulerian-Lagrangian framework.A comprehensive model is established by involving the transfer process between two phases and chemical reactions in aqueous phase,which is validatedwith the measured data froma WFGD scrubber of 330 MW coal-fired power unit.Numerical results show that the overall uniformity degree of flue gas in whole scrubber is largely determined by the force-balanced droplets in the middle part of scrubber,which is dominated by counter-current mode.Both momentum transfer behavior and SO_(2) chemical absorption process present the synchronicity with the evolution of gas-slurry flow pattern,whilst the heat transfer together with H_(2)O evaporation has little effect on overall absorption process.Three regions are firstly defined as Gas Inlet Region(GIR),Dominant Absorption Region(DAR)and Slurry Dispersed Region(SDR)from the bottom to top of scrubber.SO_(2) is mainly scrubbed in DAR,which provides much more intensive interaction between two phases compared to GIR or SDR.A better understanding of the desulfurization process is obtained from the fundamental relationship between transport phenomena and chemical reactions based upon the complicated hydrodynamics of gas-slurry two-phase flow,which should be useful for designing and optimizing the scrubber in coal-fired power unit.

Experimental study on SO_2 recovery using a sodium-zinc sorbent based flue gas desulfurization technology

A sodium–zinc sorbent based flue gas desulfurization technology(Na–Zn-FGD) was proposed based on the experiments and analyses of the thermal decomposition characteristics of Ca SO3 and Zn SO3·2.5H2 O, the waste products of calcium-based semi-dry and zinc-based flue gas desulfurization(Ca–SD-FGD and Zn–SD-FGD) technologies, respectively. It was found that Zn SO3·2.5H2 O first lost crystal H2 O at 100 °C and then decomposed into SO2 and solid Zn O at 260 °C in the air, while Ca SO3 is oxidized at 450 °C before it decomposed in the air. The experimental results confirm that Zn–SD-FGD technology is good for SO2 removal and recycling, but with problem in clogging and high operational cost. The proposed Na–Zn-FGD is clogging proof, and more cost-effective. In the new process, Na2CO3 is used to generate Na2SO3 for SO2absorption, and the intermediate product Na HSO3 reacts with Zn O powders, producing Zn SO3·2.5H2 O precipitate and Na2SO3 solution. The Na2SO3 solution is clogging proof, which is re-used for SO2 absorption. By thermal decomposition of Zn SO3·2.5H2 O, Zn O is re-generated and SO2 with high purity is co-produced as well. The cycle consumes some amount of raw material Na2CO3 and a small amount of Zn O only. The newly proposed FGD technology could be a substitute of the traditional semi-dry FGD technologies.

超重力旋转填料床中柠檬酸钠法烟气脱硫

采用柠檬酸-柠檬酸钠缓冲溶液作为吸收液,在超重力旋转填料床(简称填料床)中进行模拟烟气中SO2的吸收和解吸实验,考察了吸收液组成及各操作参数对SO2吸收率及解吸率的影响。实验结果表明:吸收过程中吸收液的柠檬酸浓度越高、吸收液初始pH越高,SO2吸收率越高;填料床转速增大、液气比增大,SO2吸收率下降速率增大;解吸过程中吸收富液中柠檬酸浓度越低、吸收富液初始pH越低,SO2解吸率越高。填料床中柠檬酸钠法脱硫的最佳工艺条件为:柠檬酸浓度1.0 mol/L,吸收液初始pH 4.5,填料床转速700～900 r/min,液气比5～7 L/m3。

基于循环经济的燃煤电厂钠法排烟脱硫

针对国内治理燃煤电厂排放的SO2,大多采用钙法(石灰石/石膏法)带来的新的污染问题,结合我国西部地区的资源特点,介绍了用烧碱脱除燃煤电厂烟气中的SO2,其脱硫液用于生产硫酸和元明粉,电石渣用于生产水泥的综合治理方法。认为在用高硫煤的大型火电厂附近建设PVC厂,用PVC厂的烧碱实施钠法脱硫,既解决了烧碱的出路,又避免了钙法脱硫石膏堆存所产生的二次污染问题。

碳酸氢钠干法脱硫+中低温SCR脱硝技术的生产实践

介绍了碳酸氢钠干法脱硫工艺和中低温SCR脱硝工艺原理及技术特点。山西太钢不锈钢股份有限公司焦化厂外排焦炉烟气ρ(SO2)≤200mg/m3、颗粒物(ρ)≤30 mg/m3、ρ(NOx)≤400 mg/m3,难以达到"2+26"城市及部分地区即将执行的特别排放限值要求。采取碳酸氢钠干法脱硫+中低温SCR脱硝技术改造后,外排烟气ρ(SO2)≤5.1 mg/m3、颗粒物(ρ)<5 mg/m3、ρ(NOx)<50 mg/m3,远低于特别排放限值要求。

钠法烟气脱硫机理研究

采用离子平衡、电荷平衡、元素平衡原理研究钠法烟气脱硫机理,建立了相关数学模型。提出了吸收液脱硫容量、单位脱硫容量等概念,并依次分析了吸收液pH值、吸收液与烟气液气比、吸收液中碳酸盐容量、烟气中SO;浓度、吸收液中亚硫酸盐容量等对单位脱硫容量和脱硫效率的影响并对其影响机理进行了解释。根据研究结论提出了钠法脱硫技术进行进一步优化的方向。

高含硫天然气净化厂烟气脱硫技术适用性分析

为适应日益严格的环保要求,烟气处理技术一直在推陈出新。对比了氨法、钠碱法、半干法烟气脱硫技术的优缺点,通过这三种技术在高含硫天然气净化尾气处理过程中的应用,分析了其实用性和经济性。可为高含硫天然气净化厂选用烟气脱硫技术提供参考。

旋转填充床中柠檬酸钠法烟气脱硫的实验研究

以柠檬酸-柠檬酸钠缓冲溶液作为吸收液,在旋转填充床中进行模拟烟气中SO2(体积分数约为0.4%)的吸收实验,考察了各操作条件对脱硫率的影响。实验结果表明:脱硫率随转子转速、液气比的增大而逐渐增大,但均是达到某一值以后基本不再增加;吸收液的初始pH值越大、温度越高、柠檬酸钠浓度越大,则脱硫效果越好。旋转床中柠檬酸钠法烟气脱硫的适宜工艺条件为:旋转填充床转速1200 r/min,液气比8~12 L/m3,吸收液的初始pH值4.5~5.0,柠檬酸钠浓度0.6 mol/L。