氨法烟气脱硫吸收过程的模拟计算

针对电厂氨法烟气脱硫的中试实验装置，选择适当的NH3—H2O—SO2体系气液平衡模型，对吸收塔的操作进行模拟计算，由进料状态参数和操作参数可计算出吸收平衡结果，所得结果与实验结果符合较好。通过模拟计算可判断吸收率、氨损耗、塔底盐浓度等目标值是否符合要求，并可对吸收塔的性能进行评估，从而为实际工业化生产提供指导。     

喷淋塔氨法烟气脱硫模型与实验研究

在氨法烟气脱硫喷淋塔的实验系统上对影响氨法脱硫效率的几个主要因素进行了实验研究。实验结果表明：提高液气比和浆液pH值、降低烟气温度和烟气空塔气速均可以提高脱硫效率。在双膜理论的基础上,通过对氨法脱硫过程中SO₂传质速率方程和螺旋型喷嘴液滴直径大小关联式的分析,建立了喷淋塔氨法脱硫的数学模型。利用该模型对影响氨法脱硫效率的几个主要因素进行计算,并与实验结果进行比较,实验数据和模型计算值基本吻合。     

氨法烟气脱硫工艺过程模拟与优化

为了进一步研究氨法烟气脱硫工艺过程,以非平衡级传质理论为依据,利用化工流程模拟软件Aspen Plus建立填料吸收塔脱除SO2过程的数值计算模型,分析和优化操作参数对脱硫效果的影响,模拟结果与文献值吻合较好。模型计算结果表明:脱硫率随着吸收液pH值和液气比的增大而增大;随着进口SO2质量浓度和进口烟气流量的增大而降低,并得出吸收液pH值及液气比在氨法烟气脱硫效率影响因素中占主要位置。所建立的氨法烟气脱硫工艺过程模型准确合理,模拟结果可为脱硫系统实际运行调节各操作参数对脱硫效果的影响提供参考和借鉴。     

湿壁塔氨法烟气脱硫模型

近年来氨法脱硫以其低投入,脱硫率高以及有价值的副产物越来越受到重视。今以并流式湿壁塔脱硫实验装置为例,以氨水作为吸收液,在20℃和常压下研究了氨法烟气脱硫的气液传质与化学反应过程,并且在伴有快速的化学反应吸收的双膜理论的基础上,建立了数学模型。利用该模型对并流式湿壁塔氨法脱硫过程进行了模拟,分析了吸收液pH值、液气比、吸收液浓度、烟气流速以及初始SO2浓度对脱硫效率的影响,并与实验结果进行了对比。结果表明:在进气浓度为2500 mg·m·3时,最佳的工艺条件为液气比为2.2~2.8 L·m·3,吸收液pH值为5.8~6.5,烟气流速为1.5~2.5 m·s-1;该模型的计算值与实验数据基本吻合,为氨法烟气脱硫的工业化应用提供了理论参考。     

氨法烟气脱硫SO_2吸收传质系数研究

喷淋塔氨法脱硫技术被广泛应用于净化烟气的SO_2,传质系数是喷淋吸收塔重要的设计和运行参数,但目前文献中有关氨法脱硫传质系数的报道很少,还有待进一步研究。在喷淋塔中对氨法脱硫SO_2吸收传质过程进行了实验研究,结合对液滴和塔壁液膜运动的计算,得到不同实验条件下SO_2的吸收传质速率,并建立了氨法脱硫SO_2吸收传质系数表达式。该传质系数包含浆液pH、烟气流速ug和液气比L/G等主要参数,能够反映不同pH、ug和L/G条件下SO_2在单位气液接触面积上的传质速率。对比验证结果表明,该传质系数计算得到的SO_2吸收传质速率与实验值之间的相对误差小于±12%,二者能够较好地吻合。建立的传质系数表达式能够为喷淋塔氨法脱硫的优化设计和运行提供理论参考。     

湿式氨法脱硫在烟气脱硫中的应用

阐述了湿式氨法脱硫的工艺、原理、设备材质选择及其在烟气脱硫中的应用情况。     

烟气氨法脱硫脱碳技术研究进展

介绍了湿式氨法脱硫技术和氨法脱碳技术.对湿式氨法脱硫技术中存在的氨逃逸、气溶胶以及铵盐结晶问题进行了阐述;对氨法脱碳技术中存在的氨逃逸以及富液再生问题进行了分析,针对这两种气体污染物处理技术所面临的问题提出了解决办法.氨水作为吸收剂可以同时吸收CO2和SO2,氨法同时脱硫脱碳技术在理论上是完全可行的.     

氨法烟气脱硫吸收塔流场数值模拟

氨法烟气脱硫工艺过程一般分为脱硫吸收、中间产品处理、副产品制造三部分,吸收塔是氨法脱硫的核心设备。以某化工厂锅炉烟气氨法脱硫项目吸收塔作为流场数值模拟对象,分析了吸收塔内的烟气流动形态。结果表明,吸收塔系统整体压降不超过2000Pa、浆液分布均匀。     

一种氨水垂直降膜吸收传质模型

在Harriott理论的基础上,提出一种新的垂直降膜吸收传质模型,将降膜过程中漩涡的作用点由一个几何点扩展到一个区域,将整个降膜流动过程划分为非湍流区和全湍流区.非湍流区内,波峰和波谷域采取了不同的Levich厚度处理方法.在全湍流区,对波动速度进行了修正.理论数据与氨水光管降膜吸收实验数据相比较,偏差在非湍流区不超过10%,在全湍流区不超过15%.扩散系数、Levich厚度及波动周期对传质系数的影响被表示为两个量纲1量之间的关系.     

填料塔气液传质参数研究（Ⅱ）──气膜传质系数

用拟一级快速化学反应吸收法测定了拉西环填料塔的气膜传质系数，并得出其无因次表达式。     

水吸收NH3的气相总传质系数研究

以氨-空气-水为物系，采用实验测定并结合经验公式，得出该物系在ψ12mm陶瓷拉西环填料中的气相总传质系数KGa的关联式。该关联式不仅简单，使用方便，且实验值与计算值较吻合。     

Kinetics of the absorption of carbon dioxide into aqueous ammonia solutions

Experiments were performed in a customized double stirred tank reactor to study the kinetics of CO₂ absorption into NH₃ solutions at concentrations ranging from 0.42 to 7.67 kmol·m^?3 and temperatures between 273.15 and 293.15 K. The results show that the reactive absorption was first order with respect to CO₂ but fractional order (1.6–1.8) with respect to ammonia. Experimental data can be satisfactorily interpreted by a termolecular mechanism using and . © 2016 American Institute of Chemical Engineers AIChE J, 62: 3673–3684, 2016     

规整填料塔中氨水吸收CO2的体积总传质系数

目前,CO₂排放问题已经成为世界各国可持续发展面临的重要挑战。以化学溶剂吸收法工艺为基础的燃烧后脱碳是当前比较成熟的已进入工业规模实验的技术路线。而氨水作为一种新的吸收剂受到广泛关注。以气相体积传质系数（K_Ga_e）作为表征,对规整填料塔中氨水吸收CO₂的传质性能进行了研究,探索了气速、CO₂分压、液速和氨水浓度对K_Ga_e的影响。实验结果表明,在本文的工况条件下,K_Ga_e随液速和氨水浓度的增大而增大,随CO₂分压的增大有所减小,气速对K_Ga_e的影响不大。实验结果对今后填料塔的设计工作的经济性和合理性有一定指导作用。     

基于浓度/速度场测量的吸收过程液相传质系数

针对矩形流道内气、液流体的并流吸收传质过程,分别应用实时激光全息干涉术和激光多普勒速度仪对不同气、液流速下液相内近界面浓度分布与速度分布进行了实验观测.结果表明,边界层内浓度分布呈指数下降,流速越大梯度越陡,且速度边界层厚度要大于浓度边界层厚度.建立了通过物料衡算求算液相传质系数的方法.得到了不同条件下平均液相传质系数,并与Whiteman’s双膜理论的计算结果进行了比较.     

Simulations of chemical absorption in pilot-scale and industrial-scale packed columns by computational mass transfer

A complex computational mass transfer model (CMT) is proposed for modeling the chemical absorption process with heat effect in packed columns. The feature of the proposed model is able to predict the concentration and temperature as well as the velocity distributions at once along the column without assuming the turbulent Schmidt number, or using the experimentally measured turbulent mass transfer diffusivity. The present model consists of the differential mass transfer equation with its auxiliary closing equations and the accompanied formulations of computational fluid dynamics (CFD) and computational heat transfer (CHT). In the mathematical expression for the accompanied CFD and CHT, the conventional methods of k-ε and are used for closing the momentum and heat transfer equations. While for the mass transfer equation, the recently developed concentration variance and its dissipation rate ε_c equations (Liu, 2003) are adopted for its closure. To test the validity of the present model, simulations were made for a pilot-scale randomly packed chemical absorption column of 0.1 m ID and 7 m high, packed with 1/2^″ ceramic Berl saddles for CO₂ removal from gas mixture by aqueous monoethanolamine (MEA) solutions (Tontiwachwuthikul et al., 1992 ) and an industrial-scale randomly packed chemical absorption column of 1.9 m ID and 26.6 m high, packed with 2^″ stainless steel Pall rings for CO₂ removal from natural gas by aqueous MEA solutions (Pintola et al., 1993). The simulated results were compared with the published experimental data and satisfactory agreement was found between them in both concentration and temperature distributions. Furthermore, the result of computation also reveals that the turbulent mass transfer diffusivity D_tvaries along axial and radial directions. Thus the common viewpoint of assuming constant D_t throughout the whole column is questionable, even for the small size packed column. Finally, the analogy between mass transfer and heat transfer in chemical absorption is demonstrated by the similarity of their diffusivity profiles.     

TLXS-1型吸收装置的流体力学及传质性能

在TLXS-1型填料塔试验装置中,以空气-氨-水为物系,对φ12mm瓷拉西环填料的流体力学及传质性能进行试验测定。获得了该塔的泛点特性和△P／Z～G、HOG—G、KY～G等相关曲线。试验研究结果对该吸收塔的操作和工程设计具有参考价值。     

新型膜蒸馏传质回热的吸收式制冷循环

提出了传质回热吸收式制冷循环,该循环在溶液回热过程中引入膜蒸馏技术,将传统吸收式制冷循环中的溶液等浓度回热过程转变为溶液变浓度回热过程。同传统吸收式制冷循环相比,该循环的发生过程向低温区移动,这对于低品位热能的利用以及提高吸收式制冷装置的热效率具有重要意义。传质回热器采用直接接触式膜蒸馏传质传热技术是可行的,传质回热吸收式制冷的理论循环与理想循环的偏差是由膜蒸馏传质回热器膜两侧溶液的蒸汽压差和膜导热引起的。     

Numerical simulation of the mass transfer process of CO2 absorption by different solutions in a microchannel

The flow and mass transfer characteristics of CO₂ absorption in different liquid phases in a microchannel were studied by numerical simulation. The mixture gas phase contained 5 vol% CO₂ and 95 vol% N₂ , and the different liquid phases were water, ethanol solution, 0.2 M monoethanolamine solution, and 0.2 M NaOH solution, respectively. Based on the permeation theory, the distribution of velocity and concentration in the slug flow was obtained by local simulation of flow and mass transfer coupling and was described in depth. The influence of contact time and bubble velocity on the mass transfer of the whole bubble was highlighted. The volumetric mass transfer coefficient on the bubble cap and liquid film, CO₂ absorption rate, and enhancement factor were calculated and analyzed. The results showed that the volumetric mass transfer coefficients of chemical absorption were ~3 to 10 times that of physical absorption and the CO₂ was absorbed more completely in chemical absorption. The new empirical correlations for predicting the mass transfer coefficient of the liquid phase were proposed respectively in physical absorption and chemical absorption, which were compared with the empirical formulas in the literature. The volumetric mass transfer coefficients obtained by predictive correlations are in good agreement with those obtained by simulation in this paper. This work made a basic prediction for CO₂ absorption in microchannel and provides a foundation for later experimental research.