Ternary System of Fe-based Ionic Liquid,Ethanol and Water for Wet Flue Gas Desulfurization

Fe-based ionic liquid （Fe-IL） was synthesized by mixing FeCl3·6H2O and 1-butyl-3-methylimidazolium chloride [Bmim]C1 in this paper. The phase diagram of a ternary Fe-IL, ethanol and water system was investigated to construct a ternary desulfurization solution for wet flue gas desulfurization. The effects of flow rate and concentration of SO2, reaction temperature, pH and Fe-IL fraction in aqueous desulfurization solution on the desulfiariza- tion efficiency were investigated. The results shows that the best composition of ternary desulfurization solution of Fe-IL, ethanol and water is 1 ： 1.5 ： 3 by volume ratio, and pH should be controlled at 2.0. Under such conditions, a desulfurization rate greater than 90% could be obtained. The product of sulfuric acid had inhibition effect on the wet desulfurization process. With applying this new ternary desulfurization solution, not only the catalyst Fe-IL can be recycled and reused, but also the product sulfuric acid can be separated directly from the ternary desulfurization system.

Effects of Magnesium and Ferric Ions on Crystallization of Calcium Sulfate Dihydrate Under the Simulated Conditions of Wet Flue-gas Desulfurization

The influences of magnesium and ferric ions in their different ratios on the rate of gypsum crystallization were studied under the conditions similar to those of wet flue-gas desulfurization（WFGD）. The results show that addition of both Mg^2＋ and Fe^3＋ increased induction time and decreased the growth efficiency up to 50% compared with the baseline（without impurities） depending on the concentration and the type of impurity. The effects of Mg^2＋ and Fe^3＋ on the surface energy and the rate of nucleation were estimated by employing the classical nucleation theory. The surface energy decreased by 8% and 14% with the addition of 0.02 mol/L magnesium or ferric ions, respectively, compared to the baseline. Mg^2＋ and Fe^3＋ made the growth rate of the （020）, （021） and （040） faces of gypsum crystal a much greater reduction, which leads to the formation of needle crystals compared to the baseline which favors the formation of plate or flakes. Furthermore, an edge detection program was developed to quantify the effects of impurities on the filtration rate of gypsum product. The results show that the inhibition efficiency of the presence of 0.02 mol/L Mg^2＋ and Fe^3＋ on the filtration rate of gypsum crystal ranges from 22% to 39%.

Experimental study on performance of flow & desulfurisation of a gas-liquid screen scrubber for wet flue gas desulfurization

In the paper, the gas-liquid two-phase flow performance and desulfurisation performance of the gas-liquid screen scrubber were experimentally studied when limestone was used as absorbent. Experiments were carried out at varying the flue gas velocity and slurry flux in concurrent and countercurrent tower respectively. The experimental results showed that the flow resistance of absorber increased rapidly with an increase of the flue gas velocity whether in concurrent or in countereurrent tower, and the up trend of the flow resistance in the cotmtercurrent tower was higher than those in the concurrent one. The influence of the flue gas velocity on the flow resistance of absorber was more than those of the slurry flux density. Whether in the concurrent tower or in the cotmtercurrent one, increasing the flue gas velocity or the slurry flux density would enhance the desulphurization efficiency. The influence of the slurry flux density on the desulfurisation efficiency was greater than those of the flue gas velocity.

Dynamic optimization oriented modeling and nonlinear model predictive control of the wet limestone FGD system

Nonlinear model predictive control(NMPC)scheme is an effective method of multi-objective optimization control in complex industrial systems.In this paper,a NMPC scheme for the wet limestone flue gas desulphurization(WFGD)system is proposed which provides a more flexible framework of optimal control and decision-making compared with PID scheme.At first,a mathematical model of the FGD process is deduced which is suitable for NMPC structure.To equipoise the model’s accuracy and conciseness,the wet limestone FGD system is separated into several modules.Based on the conservation laws,a model with reasonable simplification is developed to describe dynamics of different modules for the purpose of controller design.Then,by addressing economic objectives directly into the NMPC scheme,the NMPC controller can minimize economic cost and track the set-point simultaneously.The accuracy of model is validated by the field data of a 1000 MW thermal power plant in Henan Province,China.The simulation results show that the NMPC strategy improves the economic performance and ensures the emission requirement at the same time.In the meantime,the control scheme satisfies the multiobjective control requirements under complex operation conditions(e.g.,boiler load fluctuation and set point variation).The mathematical model and NMPC structure provides the basic work for the future development of advanced optimized control algorithms in the wet limestone FGD systems.

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.

湿法烟气脱硫(WFGD)喷淋塔内烟气流场的数值模拟研究

借助商用Fluent软件,针对300MW机组湿法烟气脱硫(WFGD)系统喷淋塔内烟气流场进行了数值模拟,详细考察了几何结构尺寸和运行参数对喷淋塔内烟气流场的影响。数值模拟结果表明,喷淋塔内烟气流场总体趋势大体上一致,几何结构尺寸和运行参数对塔内烟气流场有较大影响。

蒸汽相变促进WFGD系统脱除PM_(2.5)的协同作用分析

蒸汽相变作为预处理措施能显著提高常规除尘设备对PM2.5细颗粒的脱除效率,但对于水汽含量低的原始燃煤烟气蒸汽耗量太大,限制了工程应用,而在燃煤电厂湿法烟气脱硫(WFGD)过程中,烟气降温增湿,再添加少量蒸汽就可以建立PM2.5凝结长大所需要的过饱和环境,进而实现WFGD系统对PM2.5的协同高效脱除。在分析蒸汽相变促进PM2.5脱除影响因素的基础上,结合湿法脱硫过程传热传质特性,定性分析了脱硫塔塔前、塔内和塔出口添加蒸汽对WFGD系统脱除PM2.5的促进作用,并提出具体工艺方案。

应用润湿剂促进WFGD系统脱除细颗粒物的性能

采用旋流板塔双碱法脱硫工艺,进行了脱硫液中分别添加聚醚硅油、Compound No.3、XHG-248润湿剂促进湿法烟气脱硫(WFGD)系统脱除细颗粒物的试验研究,考察了脱硫液气比、脱硫液温度等对润湿剂作用性能的影响,并进行了协同利用蒸汽相变原理和添加润湿剂促进细颗粒物脱除的试验。结果表明:脱硫液温度对添加润湿剂的作用效果存在显著影响,常温下试验的3种润湿剂均能不同程度促进细颗粒物的脱除,脱硫液温度为45℃时,仅有Compound No.3对细颗粒物脱除有促进作用;同时在旋流板塔盘间添加适量蒸汽和脱硫液中添加Compound No.3润湿剂,可显著促进细颗粒物的脱除,脱除效率可增至65%左右。

化学团聚降低WFGD系统PM_(2.5)排放的试验研究

为了降低湿法脱硫系统（WFGD）出口PM2.5的排放量,在模拟WFGD和燃煤热态实验系统中进行了添加化学团聚剂的试验.考察了脱硫液细小晶粒含量与出口PM2.5浓度的关系以及团聚剂对脱硫液颗粒物粒径分布的影响,并对团聚剂类型、浓度、温度及脱硫操作条件等对脱硫系统的影响进行了研究,同时考察了团聚剂的加入对脱硫的影响.结果表明：WFGD出口PM2.5排放量与浆液细小晶粒含量成正相关,添加化学团聚剂可有效降低脱硫浆液中细小晶粒的数量,脱硫液中细颗粒物相对体积浓度降低38%;燃煤热态系统下添加化学团聚剂可有效降低PM2.5排放量,数量浓度降低约20%;非离子型聚丙烯酰胺团聚效果最明显,团聚效果随着脱硫液温度的升高而升高,脱硫液气比控制在15-20 L/m^3范围内比较合适,团聚剂加入不会影响脱硫性能.

己二酸和己二酸钠强化石灰石WFGD的对比研究

在湍球塔设备上进行了己二酸和己二酸钠强化石灰石WFGD的对比研究,考察了2种添加剂对脱硫过程的强化和缓冲作用,分析计算了2种添加剂对石灰石的利用率。实验结果表明,2种添加剂可以在较低浆液pH下维持较高脱硫率,并且2种添加剂均促进了CaCO3的溶解,在相同条件下己二酸钠有更好的脱硫效果,而己二酸有更好的缓冲作用,且己二酸促进CaCO3溶解的效果更显著。

WFGD水力旋流器中石灰石颗粒分级试验与数值模拟

湿法烟气脱流装置中水力旋流器分级试验表明,进口石灰石浆液的颗粒质量浓度为15%时,溢流口颗粒质量浓度达30%,溢流颗粒粒径则集中于30μm以下;随着颗粒粒径的增大,颗粒底流口回收率也在增大,当粒径达到30μm时,回收率已经接近100%。数值模拟表明,雷诺应力湍流模型、自由表面多相流动模型和斯托克斯拉格朗日模型能很好地描述水力旋流器内复杂三维运动的石灰石颗粒分级运动和规律。采用了初始边界条件不给出分流比、也不设定空气柱的模拟方法,模拟结果显示了空气柱的形成、流体的旋流流动。模拟得到的不同粒径颗粒的分级效率与高进口质量浓度条件下的试验结果吻合较好。

应用蒸汽相变促进WFGD系统脱除细颗粒的技术分析

依据蒸汽相变促进细颗粒凝并长大的机理及典型的湿法烟气脱硫(WFGD)工艺特征,提出脱硫塔出口设置蒸汽相变室,以建立细颗粒凝结长大所需要的过饱和环境,进而提高WFGD系统对细颗粒的脱除效率。综合WFGD系统的腐蚀机理及水汽不易在低表面能材料表面凝结的特性,提出采用具有良好耐腐蚀性能的低表面能材料作为凝结室的内壁面或壁面衬里、涂料,以实现增进相变效果及防止酸性物质结露腐蚀的双重功效。

OI^2-WFGD烟气脱硫技术介绍

系统介绍了湿法烟气脱硫技术的发展现状与趋势 ,着重介绍江苏苏源环保工程股份有限公司的火电厂大型发电机组烟气脱硫 (OI2 -WFGD)技术的研究内容、技术创新点 ,初步预测了推广使用该核心技术所带来的经济效益。

OI^2-WFGD-Ⅱ烟气脱硫技术介绍

简要介绍了江苏苏源环保工程有限公司开发的OI2-WFGD-Ⅱ湿法烟气脱硫技术的工艺特点、设备布置、技术参数、设备国产化以及技术应用。

基于PCS7的WFGD石灰石浆液控制系统设计

基于SIEMENS公司的PCS7控制系统开发平台,为某电厂2×300MW燃煤机的石灰石/石膏湿法烟气脱硫系统设计石灰石浆液控制控制系统。详细介绍了控制系统的硬件配置和软件组态。

WFGD系统脱硫及脱汞特性模拟研究

以石灰石-石膏湿法脱硫系统为研究对象,应用Aspen Plus软件对脱硫系统的协同脱汞性能进行了模拟,重点研究了脱硫系统工艺参数对脱硫及脱汞效率的双重影响。结果表明：脱硫装置能够提高烟气中汞的去除效率,提高液气比及脱硫系统入口氧气浓度,同时能够提高脱汞及脱硫效率,脱汞及脱硫效率随入口SO2浓度的提高而降低。pH值在5.5～6之间时,脱汞及脱硫效率均达到较高水平,提高烟气温度和浆液温度则会降低脱汞效率。

Comparison of deep desulfurization methods in alumina production process

Several methods of deep desulfurization in alumina production process were studied, and the costs of these methods were compared. It is found that most of the S2- in sodium aluminate solution can be removed by adding sodium nitrate or hydrogen peroxide in digestion process, and in this way the effect of S2- on alumina product quality is eliminated. However, the removal efficiency of 2?32OS in sodium aluminate solution is very low by this method. Both S2- and 2?32OS in sodium aluminate solution can be removed completely by wet oxidation method in digestion process. The cost of desulfurization by wet oxidation is lower than by adding sodium nitrate or hydrogen peroxide. The results of this research reveal that wet oxidation is an economical and feasible method for the removal of sulfur in alumina production process to improve alumina quality, and provide valuable guidelines for alumina production by high-sulfur bauxite.

Study on Industrial Application of Hydrogen Sulfide Removal by Wet Oxidation Method with High Gravity Technology

The removal of hydrogen sulfide from gas plays an important role in rational utilization of resources and environ- mental protection. In this paper, the process of hydrogen sulfide removal by wet oxidation method in a rotating packed bed was investigated in a scale for treating 10 000 Nm3/h of gas. On the basis of studying the influence of the species and con- centration of alkali source, the liquid/gas volume ratio, the high gravity factor, and the hydrogen sulfide content in feed gas on the desulfurization effect, the suitable technological conditions were obtained. The hydrogen sulfide removal efficiency could reach 98.0% under these conditions. The results of continuous operation of process facilities showed that the high gravity method has many merits including higher desulfurization rate, good stability in operation, lower liquid/gas volume ratio, greater operation elasticity, and apparent energy saving effects.

Model Free Adaptive Predictive Control of Desulfurization Slurry pH Based on CPS Framework

In order to improve the slurry pH control accuracy of the absorption tower in the wet flue gas desulfurization process,a model free adaptive predictive control algorithm for the desulfurization slurry pH which is based on a cyber physical systems framework is proposed.First,aiming to address system characteristics of non-linearity and pure hysteresis in slurry pH change process,a model free adaptive predictive control algorithm based on compact form dynamic linearization is proposed by combining model free adaptive control algorithm with model predictive control algorithm.Then,by integrating information resources with the physical resources in the absorption tower slurry pH control process,an absorption tower slurry pH optimization control system based on cyber physical systems is constructed.It is turned out that the model free adaptive predictive control algorithm under the framework of the cyber physical systems can effectively realize the high-precision tracking control of the slurry pH of the absorption tower,and it has strong robustness.

WFGD中喷淋塔液气比计算方法的探讨

从湿法烟气脱硫的数学模型着手,介绍了传质系数法和传质单位数法两种喷淋塔液气比计算和选择的方法,对于自主开发适合国内脱硫市场的喷淋塔液气比计算模型有参考意义。液气比的计算模型是建立在大量实验数据之上的,需要经大量实际工程数据的验证和修正才能用于指导WFGD工程喷淋塔的设计。