【作者】 李强；

【导师】 方梦祥； 杨立勇；

【作者基本信息】 浙江大学 ， 动力工程， 2021， 硕士

【摘要】 化学吸收法是大规模捕集烟气二氧化碳最成熟技术之一,目前主要存在系统投资过高和吸收液再生能耗较大的问题。贫富液换热器用于回收再生塔出口贫液热量,吸收液再生能耗随贫富液换热器冷贫液-冷富液端差减小而降低。传统不锈钢管壳式换热器应用于化学吸收法碳捕集过程存在换热系数低和占地面积大等问题,导致贫富液换热器经济换热端差较高。全焊接板框式换热器换热效率高,体积紧凑、承压能力高于可拆式板换,可以解决易泄漏、传热端差大的问题,芯体与四周压板还可以分体拆卸,便于设备清洗维护。本文研究用于碳捕集系统贫富液换热的高效全焊接板框式换热器,根据30wt%一乙醇胺（MEA）/水测试数据验证并优化CFD数值计算模型,模拟了较高粘度吸收剂使用的波纹板式全焊接板式换热器热工性能,并对波纹板型的波纹倾角和波纹高度等参数进行了模拟优化,得到了用于贫富液换热器的最优板型。在此基础上着重研究了胶囊板型的热工性能,并根据研究成果完成了15万吨/年碳捕集项目贫富液换热器设计选型。本论文主要研究内容和结果包括:（1）板式换热器数值模拟模型建立;根据实验装置板型参数缩小构建了几何模型,通过数值模拟研究吸收液在0.1-0.7 m/s流速条件下温度场、速度场和压力场,并通过不同湍流模型计算值与实验数据对比筛选,选取与实验值相差最小的是SST k-ε模型作为数值计算湍流模型;（2）研究波纹高度和波纹倾角变化对换热系数和阻力损失的影响;研究版型倾斜角β变化范围为40°-70°,波纹高度δ变化范围为1.5-4.5mm条件下,吸收液在不同流速条件下的温度场、速度场和压力场;研究结果表明在波纹倾角60°时错叉流和Z字流达到了共振效果,实现了最佳的湍流状态。同时随波纹高度继续增加,流体自波顶切向下滑至波纹凹陷后会形成旋涡反弹,导致错叉流力度逐渐减小,随着流体湍动流线减少,传热减弱。在波纹倾角60°、波纹高度在3.5mm时达到最佳湍流传热效果。（3）针对高粘度吸收剂开发了胶囊型板式换热器。对胶囊型板式换热器中单相流动和传热进行数值模拟并对结果进行分析,发现由凹形胶囊的形状和排列所形成的涡旋,涡旋和流体的冲刷加强了凹胶囊上游和凸胶囊下游的传热效果。（4）国能锦界电厂15万吨/年烟气CO₂捕集系统采用胶囊板式的全焊接板式换热器,设计换热系数为1563 W/m².K,换热面积为2000m²,并给出最终产品应用结果及设计对比,说明换热器应用前景。更多还原

【Abstract】 The chemical absorption method is one of the most mature technologies for large-scale capture of flue gas carbon dioxide.At present,there are mainly problems of high system investment and large energy consumption of absorption liquid regeneration.The lean-rich liquid heat exchanger is used to recover the heat of the lean liquid at the outlet of the regeneration tower,and the regeneration energy consumption of the absorption liquid decreases with the decrease of the cold lean liquid-cold rich liquid TTD（Terminal temperature difference）of the lean rich liquid heat exchanger.The traditional stainless steel shell-and-tube heat exchanger used in the chemical absorption carbon capture process has problems such as low heat transfer coefficient and large footprint,resulting in a high economic TTD of the lean-rich liquid heat exchanger.All-welded plate-and-frame heat exchangers have high heat exchange efficiency,compact size,and higher pressure-bearing capacity than detachable plate-and-frame heat exchangers,which can solve the problems of easy leakage and large TTD.,which is convenient for equipment cleaning and maintenance.In this paper,a high-efficiency all-welded plate-and-frame heat exchanger for heat exchange of lean and rich liquids in carbon capture systems is studied.According to the test data of 30wt%monoethanolamine（MEA）/water,the CFD numerical calculation model is verified and optimized,and the higher viscosity absorption is simulated.The thermal performance of the corrugated plate fully welded plate heat exchanger used with the agent was investigated,and the parameters such as the corrugated inclination angle and corrugation height of the corrugated plate were simulated and optimized,and the optimal plate type for the poor-rich liquid heat exchanger was obtained.On this basis,the thermal performance of the capsule plate type is emphatically studied,and the design and selection of the lean-rich liquid heat exchanger for the 150,000-ton/year carbon capture project is completed according to the research results.The main research contents and results of this paper include:（1）The numerical simulation model of the plate heat exchanger was established;the geometric model was constructed according to the reduction of the plate parameters of the experimental device,and the temperature field,velocity field and pressure field of the absorbing liquid were studied through numerical simulation under the condition of 0.1-0.7 m/s flow velocity,By comparing the calculated values of different turbulence models with the experimental data,the SST k-εmodel with the smallest difference from the experimental values is selected as the numerical turbulence model;（2）Study the influence of corrugation height and corrugation inclination on the heat transfer coefficient and resistance loss;under the condition that the variation range of the pattern inclination angleβis 40-70°,the variation range of the corrugation heightδis 1.5-4.5mm,the absorption liquid temperature field,pressure field under different flow velocity conditions;the research result show that when the corrugation inclination angle is 60°,the cross flow and the Z-shaped flow achieve resonance effect and achieve the best turbulent flow state.meanwhile,as the corrugation height continues to increase,the fluid will form a vortex rebound after sliding tangentially from the top of the wave to the corrugation depression,resulting in a gradual decrease in the strength of the cross flow.The best turbulent heat transfer effect is achieved when the corrugation inclination is 60°and the corrugation height is 3.5mm.（3）Capsule-type plate heat exchangers are developed for high viscosity absorbents.Numerical simulation of single-phase flow and heat transfer in a capsule-type plate heat exchanger was carried out and the results were analyzed.It was found that the vortex formed by the shape and arrangement of the concave capsule,the vortex and the scouring of the fluid strengthened the upstream and downstream of the concave capsule.Heat transfer effect downstream of the convex capsule.（4）The 150,000 tons/year flue gas CO₂ capture system of Guoneng Jinjie Power Plant adopts a capsule-type all-welded plate heat exchanger with a design heat transfer coefficient of 1563 W/m2.K and a heat exchange area of 2000 square meters.The application results and design comparison of the final product are given to illustrate the application prospect of the heat exchanger.更多还原