石灰石湿法烟气脱硫效率影响因素分析

介绍石灰石-石膏湿法脱硫系统,并结合实际工程分析SO2入口浓度、烟气流量、塔内烟气流速、pH值、液气比和吸收区高度对脱硫效率的影响.     

船舶废气脱硫塔内流场设计研究北大核心CSCD

研究船舶废气脱硫塔内流场优化设计,为提高脱硫塔脱硫效率及降低塔内压损,利用子域技术建立脱硫塔体网格模型,使用有限差分法进行数值运算,并采用CFD软件对塔内流场进行数值仿真。基于RANS湍流模型模拟废气流速分布,得到仿真结果与实际较符合,证明模型可靠。提出了多流体模型与分散型k-ε湍流模型并用来模拟气液两相流,研究发现塔内存在"壁流"现象、气液接触不均匀等问题。通过改变废气入口位置及喷嘴支撑臂长,对塔内流场进行优化设计,结果表明,废气沿切线方向进入利于流场均匀分布,延长喷嘴支撑臂长可降低塔内压损,为废气脱硫塔内流场优化设计提供了依据。     

船用脱硫塔两相流场特性仿真

为研究脱硫塔内部两相流场特性，建立起有效三维模型以及网格模型，并利用计算流体方法对于脱硫塔内气液两相流场进行模拟，重点研究了气相的流场、温度场、压力场以及气液两相的流场、温度场。将烟气和洗涤液分别设定为523k和305k,分析了喷淋前后相关压力、温度场以及喷雾液滴运动和蒸发特性。结果表明：两层喷淋后废气得到有效降温，与液滴接触效果较好，喷雾条件对于废气通道起到较好的整流作用，保持了液滴的充盈度。脱硫塔内部流场分布情况的分析，对于流场优化以及脱硫效率的提高具有指导作用。     

脱硫塔优化设计的仿真与实验研究

研究发电厂降低SO2排放优化问题,为研究脱硫塔内不同给料方式的气固两相流流场对脱硫效率的影响,提出了采用多相流数值仿真的数学模型,并采用CFD软件对脱硫塔内流场进行了数值仿真.利用PIV技术测量实验数据,并将计算与实验测量的径向速度、轴向速度以及不同给料方式下SO2的排放量等数值进行了对比分析.经过仿真,结果表明,仿真结果与实验台测量值基本相符,并且在Z=150mm的密相区位置,双侧给料方式径向速度分布均匀,轴向速度呈现“环核流动”结构,利于物料与烟气充分混合,既能解决塔内物料堵塞,增强脱硫塔内循环,又可以提高脱硫效率,降低了SO2的排放量.     

数值模拟喷嘴对多级多尺度液柱塔内部流场的影响

为了探索不同喷嘴对液柱塔的影响,本文希望以新型的多级多尺度液柱塔为研究对象,利用流体力学软件CFD模拟压力旋转和扇形雾化喷嘴,找出它们影响塔内流场分布的规律.以雷诺时均的奈维-斯托克斯方程(N-S)为基础,采用Lagrange离散相模型,预测喷嘴对气体流场分布的影响.数值模拟与实验结果表明,在压力旋转和扇形喷嘴组合使用条件下,浆液喷淋对烟气具有明显的整合作用,防止气体撞击,避免了雾沫夹带现象.模拟液气比与实验值的误差为4.6%,证明模拟液柱塔的模型比较实用.由于在模拟过程中忽略了内部构件对气液运动轨迹的影响,所以模拟结果存在一定的局限性.尽管模拟结果与实验数据有一定差距,但二者显示了相同的现象.尤其是通过颗粒轨迹的模拟研究之后,可以清楚地看出单级喷嘴存在的缺陷,为液柱塔喷嘴选择提供了重要的参考依据.     

脱硫吸收塔出口形式流场分析及优化设计研究

脱硫吸收塔的结构型式对塔内烟气流场分布影响大,进而影响系统的烟气阻力、脱硫效率及除尘除雾效果。本文以张家口电厂8#机脱硫吸收塔为例,对吸收塔出口形式流场进行研究分析并优化,为相关工程设计提供参考和借鉴。     

基于工业脱硫塔数值仿真的喷淋速度控制研究

研究工业用脱硫塔内的烟气流动轨迹优化控制问题,以准确控制脱硫液体的喷淋速度。在脱硫塔中对烟气进行脱硫液体喷淋时,受喷淋液体的冲击使得塔内液滴轨迹突变,运动轨迹特征极难被捕获,传统仿真方法无法有效捕获突变的液滴轨迹,造成SO2吸收识别不准确,不能准确控制喷淋速度。为此,提出采用统计分析法的数值仿真方法,选用液滴的路径特征来追踪液滴轨迹,并在Euler坐标系下处理流体相,根据统计分析法实现脱硫塔内的烟气液滴的数值仿真,通过建立SO2吸收模型,根据SO2吸收特性控制脱硫液体的喷淋速度。实验表明,改进方法能够有效捕获突变液滴的运动轨迹,完成脱硫塔内的烟气流动轨迹特点仿真,构造SO2吸收模型并准确控制脱硫液体的喷淋速度。     

湿法烟气脱硫塔计算机辅助设计系统

采用Visual C 工具对湿法烟气脱硫塔的AutoCAD进行了二次开发，开发出了湿法烟气脱硫塔计算机辅助设计系统。在此基础上，对其开发的方法和技术进行了研究。结果表明，所开发出的湿法烟气脱硫塔设计系统可靠性强、操作简单、界面可视化，极大地提高了脱硫塔的设计效率与质量。     

基于Aspen Plus软件的循环流化床烟气脱硫模型

本文研究和模拟循环流化床烟气脱硫的流程和模型.以微元分析SO2的传质为基础,建立循环流化床烟气脱硫的数学模型,模型用双膜理论分析脱硫反应对SO2传质过程的增强影响,并采用惯性碰撞理论解释浆滴的形成过程.借助Aspen Plus过程模拟平台,用FORTRAN语言编写基于该模型的用户单元模块,模拟循环流化床烟气脱硫工艺,分析Ca/S、增湿水量、塔内颗粒物浓度、水滴粒径等参数对脱硫的影响,模拟计算结果和实验数据的对比显示模型能如实反映实际的趋势.本文为应用循环流化床烟气脱硫技术提供参考.     

SHG-Ⅱ-Z型脱硫除尘设备内三维两相流场的数值模拟

采用RNG k-ε湍流模型,应用Fluent软件对SHG—Ⅱ—Z型脱硫除尘装置内三维两相流场进行了数值模拟,给出了压力、速度、湍流动能、湍流强度等参数的分布,并对固体颗粒的运动轨迹进行了计算。结果显示烟气在塔内旋转上升及壁面水膜有利于提高除尘效率,从人口底部进人设备的颗粒越容易被分离。计算结果对设备现场运行工艺参数优化及脱硫除尘塔的设计有一定的指导意义。     

计算流体力学在烟气脱硫中的应用

为优化脱硫吸收塔内流场分布,提高脱硫效率,降低脱硫投资和运行成本,提出基于RANS方程和多相流模型的烟气脱硫数值模拟方法,基于FLUENT采用多相流模型针对吸收塔内烟气脱硫过程进行模拟.通过对吸收塔烟气和浆液区域进行建模及网格划分,并对内部和喷枪局部处流场进行数值模拟,分析得到浆液和烟气在吸收塔内的流动规律.模拟结果验...     

石灰石/石膏湿法烟气脱硫塔的实时仿真研究

以某火力发电厂烟气脱硫系统为研究对象,在系统机理研究的基础上,建立了湿式石灰石/石膏烟气脱硫塔的数学模型.为了满足实时仿真的需要,采用集总参数法和模块化建模方法分别建立了反应装置和氧化槽的动态数学模型,并采用了变步长的欧拉算法进行仿真运算.在仿真模型的基础上,进行了一系列的动态仿真试验,仿真结果与实际系统的动态特性相符,证明了模型的正确性.通过实时性测试和具体分析证明了模型计算的实时性.模型的建立,为湿式石灰石/石膏烟气脱硫系统的工程分析和实时仿真机的开发奠定了基础.     

Dynamic analysis and control of sieve tray gas absorption column using MATALB and SIMULINK

The present work highlights the powerful combination of SIMULINK/MATLAB software as an effective flowsheeting tool which was used to simulate steady state, open and closed loop dynamics of a sieve tray gas absorption column. A complete mathematical model, which consists of a system of differential and algebraic equations was developed. The S-Functions were used to build user defined blocks for steady state and dynamic column models which were programmed using MATLAB and SIMULINK flowsheeting environment. As a case study, the dynamic behaviour and control of a sieve tray column to absorb ethanol from CO₂ stream in a fermentation process were analysed. The linear difference equation relating the actual and equilibrium gas phase compositions was solved analytically to relate the actual gas phase composition to the liquid phase with Murphree tray efficiency as a parameter. The steady state mathematical model was found to be nonlinear (w.r.t. number of stages) due to the introduction of the Murphree tray efficiency. To avoid the solution of large linear algebraic system, a sequential steady state solution algorithm was developed and tested through the idea of tearing the recycle stream in the closed loop configuration. The number of iterations needed to achieve a given tolerance was found to be function of the Murphree tray efficiency. The open-loop dynamic analysis showed that the gas phase composition response was nonlinear with respect to the inlet gas flow rate, while it was linear with respect to inlet gas composition. The nonlinearity increased along the column height and was maximum at the top tray. On the other hand, the Murphree tray efficiency had little effect on the dynamic behaviour of the column. The controlled variable was found to exhibit fairly large overshoots due to step change in the inlet gas flow rate, while the PID controller performance was satisfactory for step change in the inlet gas composition. The closed-loop dynamic analysis showed that the controlled variable (outlet gas phase composition) had a fairly linear dynamics due to step changes in the set point.     

Impact of inlet design on mass transfer in gas–liquid rectangular microchannels

The length of the gas bubbles as well as of the liquid slugs in Taylor flow in rectangular microchannels was studied. At constant flow ratios of the gas and the liquid phase, we were able to vary the unit cell length, and therefore the gas bubble length as well as the liquid slug length by factor 4 solely by changing the inlet geometry. Based on literature and experimental data, we state a new correlation to predict the gas bubble length, the liquid slug length as well as the pressure drop for rectangular microchannels. The observed decrease in slug length for the investigated case corresponds to an increase in the Sherwood number and therefore of the mass transfer by a factor of 1.6. Short unit cell lengths, meaning enhanced mass transfer within the liquid slug and increased interfacial area, can be achieved for given flow rates using a small gas inlet channel compared to the main channel and injection in flow direction.     

Effect of operating conditions and liquid physical properties on the size of monodisperse microbubbles produced in a capillary embedded T-junction device

The aim of this study was to investigate the effect of operating parameters such as liquid flow rate, gas inlet pressure, and capillary diameter as well as the influence of the physical properties of the liquid, in particular viscosity, on the generation of monodisperse microbubbles in a circular cross section T-junction device. Aqueous glycerol solutions with viscosities ranging from 1- to 100 mPa s were used in the experiments. The bubble diameter generated was studied for systematically varied combinations of gas inlet pressure, liquid flow rate, and liquid viscosity with a fixed capillary inner diameter of 150 μm for the liquid and gas inlet channels as well as the outlet channel. In addition, the effect of channel geometry on bubble size was studied using capillaries with inner diameters of first 100 and then 200 μm. In all the experiments the distance between the coaxial capillaries at the junction was set to be 200 μm. All the microbubbles produced in this study were highly monodisperse (polydispersity index <1 %) and it was found, as expected, that bubble formation and size were influenced by the ratio of liquid to gas flow rate, capillary size, and liquid viscosity. The experimental data were then compared with empirical scaling laws derived for rectangular cross-section junctions. In contrast with these previous studies, which have found bubble size to be dependent on either the flow rate ratio (the squeezing regime) or capillary number (the dripping regime), in this experimental study bubble size was found to depend on both capillary number and flow ratio.     

液体空气汽液平衡计算模型

汽液平衡计算是精馏塔模拟计算中重要的组成部分。以液体空气汽液平衡计算为研究对象,利用神经网络技术,建立了总压（P）和各组分液相组成（X1、X2、X3）为输入节点,3种不同参数作为输出节点。（1）平衡温度（T）、各组分汽相组成（Y1、Y2、Y3）;(2)平衡温度（T）、各组分平衡常数（K1、K2、K3);（3）平衡温度（T）、汽相氮组成（Y1）及氩、氧平衡常数（K2、3））的BP神经网络模型。通过计算比较,第三种参数作为输出节点的液体空气汽液平衡计算模型,不仅具有良好的学习能力,而且预测结果也比较满意。对进一步研究并应用于空分塔模拟计算具有一定的指导意义。     

微流体温度控制器的数值模拟与特性分析

为了满足微电子封装过程对器件温度变化的精确控制,提出一种快速升降温的微型流体温度控制器,并采用流体力学软件FLUENT对温度控制器的液体—固体—空气一体化的流动—热传导过程进行数值模拟。在给定进口液体温度变化特征的情况下,通过数值分析考察控制器表面温度对进口液体温度变化的响应特性,包括时间跟随性(传热灵敏度)和温度变化振幅的衰减率(传热效率)。考察了控制器结构尺度、进口液体速度、温度变化波形、周期等参数对温度控制器的特性影响。结果表明:控制器厚度增加,控制器表面温度变化幅值衰减增大;控制器进口流速大,控制器表面温度变化幅值衰减率小;进口液体温度变化周期短,传感器表面温度变化幅值衰减增大;进口温度变化方形波的传热效率大于三角波形;传感器表面温度变化周期与进口温度周期相同,但存在相位差。     

固定床中邻二甲苯氧化的二维非均相模拟

采用二维非均相模型，模拟了邻二甲苯固定床氧化反应器，对于气相方程，使用Ｃｒａｎｋ－Ｎｉｃｏｌｓｏｎ预测－校正格式求解，对于颗粒相方程，使用中心差分并结合迭代方法求解，比较了二维非均相模型和二维拟均相模型的差别，使用二维非均匀相模型，分析了原料进口温度、进料气速、进口浓度、熔盐温度和催化剂尺寸的大小对反应的影响。     

烟气脱硫过程在线监控系统设计与应用

基于某热电厂烟气在线监测系统现状,以热电厂锅炉烟气脱硫过程为对象,构建稳定可靠的企业污染物过程在线监控系统和环保状态监测网络,同时完成对远端脱硫设备状态在线监测与远程控制,完整地掌握系统的烟气排放对环境质量影响的动态变化,为上级环保部门决策提供依据。系统已经成功应用,运行效果良好,具有推广价值。