【作者】 刘伟；

【导师】 张学军； 江龙；

【作者基本信息】 浙江大学 ， 动力工程及工程热物理， 2025， 博士

【摘要】 温室气体排放导致的全球变暖日益加剧,为实现“力争2030年前二氧化碳排放达到峰值,2060年前实现碳中和”的“双碳”目标,发展高效节能的碳捕集技术至关重要。基于固体吸附的燃烧后碳捕集技术因改造便捷、成本相对较低等优势,被视为一项极具应用潜力的技术。然而,较高的再生能耗与抽汽-再生温位间的不匹配严重制约了耦合系统的能量效率与（火用）效率。因此,开发适用于燃煤电厂的低能耗吸附碳捕集技术尤为关键。本文从热力学角度构建了吸附碳捕集热力学循环与能效评价体系,从动力学角度探明了多级传质阻力协同控制下的规整颗粒跨尺度传质动力学特性,从全系统角度形成了适用吸附碳捕集的稳态能质匹配方法与动态协同调度策略。主要工作与结论如下:（1）针对复杂热力学窗口条件下吸附热力学循环构建与综合性能评价尚不完善的问题,本文建立了捕集再生侧与余热供给侧的循环协同机制,提出了热泵辅助吸附碳捕集方法,对比了三种物理吸附材料和两种化学吸附材料的热力学性能和经济性表现。本文提出的增量分级再生辅助方法采用增量型吸收式热泵实现再生过程的分段加热,可使得沸石13X、Mg-MOF-74和MIL-101（Cr）-PEI的循环再生热耗分别降低至少14.1%、9.65%和15.0%;提出的冷热分级协同辅助方法采用吸收式冷机和温升型吸收式热泵实现循环吸附量提升,冷机和热泵使沸石13X循环吸附量的最大提升量分别为0.668 mol·kg^-1和0.921 mol·kg^-1。成本分析表明,沸石13X和活性炭的材料和再生成本均在$10-55 USD·t^-1间,更利于现有的商业化运营项目;Mg-MOF-74较低的能耗带来了显著的再生成本优势,但商业化运营仍需进一步降低材料成本。（2）针对多级传质阻力控制下规整颗粒在吸附反应器内传质动力学特性尚不明晰的问题,本文揭示了规整颗粒在跨膜、大孔和微孔扩散控制下的传质动力学关键步骤,采用实验获得了材料的大孔与微孔扩散系数,采用三维模拟阐明了从颗粒到堆积床的跨尺度传质动力学特性。本文基于热重与等温线实验数据,捕捉了材料在早期行为和后期行为下多级传质阻力的主导成分,并拟合获得了温度依赖的大孔扩散系数和表面覆盖度修正的微孔扩散系数。构建了15°、30°、45°、60°和75°倾角的柱形颗粒跨膜传质模型,提出了柱形颗粒的平均跨膜传质经验关联式。在流速为0.05 m·s^-1时,柱形颗粒的传质舍伍德数为球形颗粒的61.6%,但较小的特征长度使得柱形颗粒的跨膜传质系数比球形颗粒高7.69%,展现出更小的跨膜传质阻力。球形和柱形颗粒随机堆积吸附床的模拟结果与实验结果具有很高的一致性。吸脱附动力学结果表明,材料的热力学平衡吸附量与动力学吸附速率对吸附量变化存在协同控制关系,该趋势在球形颗粒上更加显著。（3）针对捕集-发电耦合整厂系统在全工况下的多能流优化调控策略尚不成熟的问题,本文探明了面向吸附碳捕集的稳态能质匹配机制,阐明了抽蒸汽在短期负荷变化下的动态运行特性,形成了变负荷工况下的全系统协同调控策略。本文基于热泵辅助吸附碳捕集方法,构建了增量型吸收式热泵辅助的动态变温真空吸附碳捕集耦合系统。响应面和方差分析结果表明传质系数和有效导热系数对系统性能均起到决定性作用,而再生温度对系统的再生热耗影响并不显著。当再生温度从393 K增加到413 K时,耦合流程的再生热耗从1.93 GJ·t^-1增加至2.05 GJ·t^-1,但系统的再生热耗降低比例从13.8%降低至15.5%。热泵中温预热时间会略微降低系统CO₂纯度和回收率,当预热时间从3 h降低至1 h时,纯度和回收率分别仅降低0.03%和0.48%,而再生热耗可降低0.21 GJ·t^-1。研究进一步构建了耦合吸附碳捕集与热泵系统的稳态燃煤电厂全系统模型,形成了基于凝汽器、烟气和压缩余热回收的整厂吸附碳捕集能质匹配方法。在再生热耗2.8 GJ·t^-1,回收率90%的情况下,采用增量型热泵回收凝汽器余热的分级加热耦合方案可使得再生过程的熵产从191.0 k J·K^-1·s^-1降低至126.7 k J·K^-1·s^-1,电厂发电效率损失可降低至6.50%;若结合抽汽位置调整、烟气与多级压缩余热回收,效率损失可进一步低至5.06%。本研究构建了吸附碳捕集-燃煤电厂动态耦合系统,形成了基于电厂输出负荷的吸附碳捕集系统运行调度方案。系统在变负荷工况下的平均再生热耗范围为2.1 GJ·t^-1-2.2 GJ·t^-1。仅增加灵活运行状态的吸附床将会使得系统的再生热耗增加,而将处于灵活运行状态的吸附床调整至正常运行时则会使得再生热耗降低,这主要是由于系统在低负荷下再生时的净再生量受到蒸汽温度降低的影响。增加处于灵活运行状态和正常运行状态的吸附床均会使得系统的比煤耗降低,方案7-1-0的比煤耗最小为0.054 kg_coal·kg_CO2^-1。经济性分析结果表明,吸收碳捕集和吸附碳捕集在临界规模下的碳捕集平准化成本可降低至$50.9 USD·t_CO2^-1和$35.9USD·t_CO2^-1;当调峰深度不足以满足捕集能耗要求时,系统需要支付额外的电价与蒸汽价格,此时吸收和吸附碳捕集系统的捕集成本将会略微升高至$54.0USD·t_CO2^-1和$36.7 USD·t_CO2^-1。更多还原

【Abstract】 The intensification of global warming caused by greenhouse gas emissions underscores the critical need to develop high-efficiency and energy-saving carbon capture technologies.It is essential to meet China’s"Dual Carbon"goals of peaking carbon dioxide emissions by 2030 and achieving carbon neutrality by 2060.Post-combustion carbon capture utilizing solid adsorbents is regarded as a highly promising technology due to its advantages,such as ease of retrofitting and relatively low cost.However,its application is significantly constrained by high regeneration energy consumption and the temperature mismatch between steam extraction and regeneration,which severely undermine the energy and exergy efficiency of the integrated system.Therefore,the development of low-energy-consumption adsorption carbon capture technologies suitable for coal-fired power plants is particularly crucial.This paper establishes a thermodynamic cycle and energy efficiency evaluation framework for adsorption-based carbon capture from a thermodynamic perspective,elucidates the cross-scale mass transfer kinetics of structured particles under synergistic control of multi-stage mass transfer resistances from a kinetic standpoint,and develops steady-state energy-mass match methods along with dynamic cooperative scheduling strategies applicable to adsorption carbon capture system from a holistic system approach.The main work and conclusions are as follows:（1）To address the insufficient development of adsorption thermodynamic cycle construction and comprehensive performance evaluation under complex thermo-dynamic window conditions,this study establishes a cyclic synergy mechanism between the capture-regeneration and waste heat supply side,proposes heat pump-assisted adsorption carbon capture methods,and compares the cycle performance and economic indicators of three physical adsorbents and two chemical adsorbents.The incremental stepwise regeneration assistance method proposed in this study employs an absorption heat pump to achieve segmented heating during the regeneration process,reducing the cyclic regeneration heat consumption of zeolite 13X,Mg-MOF-74,and MIL-101（Cr）-PEI by at least 14.1%,9.65%,and 15.0%,respectively.The heating-cooling synergistic assistance method utilizes the absorption chiller and absorption heat ransformer to enhance cyclic adsorption capacity,with maximum adsorption capacity improvements of 0.668 mol·kg^-1 and 0.921 mol·kg^-1 for zeolite 13X achieved by the chiller and heat pump,respectively.Cost analysis demonstrates that both zeolite 13X and activated carbon exhibit material and regeneration costs within the$10-55 USD·t^-1 range,making them more suitable for existing commercial operations.While the lower energy consumption of Mg-MOF-74 provides significant regeneration cost advantages,further reduction in material costs remains necessary for commercial implementation.（2）To elucidate the mass transfer kinetics of structured particles in adsorption reactors under multi-stage mass transfer resistance control,this study identifies the key rate-determining steps in film,macropore,and micropore diffusion processes,obtains material macropore and micropore diffusion coefficients through experimental measurements,and clarifies the cross-scale mass transfer characteristics from individual particles to packed beds using three-dimensional simulations.This study determines the dominant components of multistage mass transfer resistance during early-stage and late-stage behaviors based on thermogravimetric and isothermal experimental data,and obtains temperature-dependent macropore diffusion coefficients and surface coverage-modified micropore diffusion coefficients.The research constructs film mass transfer models for cylindrical particles at 15°,30°,45°,60°,and 75°inclination angles,and develops an empirical correlation for average film mass transfer in cylindrical particles.At a flow velocity of 0.05 m·s^-1,the results demonstrate that cylindrical particles achieve a Sherwood number that is 61.6%of spherical particles,while the smaller characteristic length yields a 7.69%higher film mass transfer coefficient than spherical particles,indicating reduced film mass transfer resistance.Simulation results for randomly packed beds of spherical and cylindrical particles show strong agreement with the experimental data.The adsorption-desorption kinetics analysis reveals a synergistic relationship between thermodynamic equilibrium capacity and kinetic adsorption rate in controlling adsorption capacity variations,with this trend being more pronounced in spherical particles.（3）To address the underdeveloped optimization and control strategies for multi-energy flows in integrated capture-power generation systems under full operating conditions,this study investigates the steady-state energy-mass match mechanism for adsorption-based carbon capture,elucidates the dynamic operational characteristics of steam extraction under short-term load variations,and formulates a coordinated system-wide regulation strategy for variable load conditions.Based on the heat pump-assisted adsorption carbon capture method,this study constructs a dynamic temperature vacuum swing adsorption carbon capture system integrated with an absorption heat pump.Response surface and variance analysis results determine that both the mass transfer coefficient and effective thermal conductivity play decisive roles in system performance,while the regeneration temperature demonstrates an insignificant effect on system regeneration heat consumption.When the regeneration temperature increases from 393 K to 413 K,the regeneration heat consumption of the coupled process rises from 1.93 GJ·t^-1 to 2.05 GJ·t^-1,but the proportion of system regeneration heat reduction improves from 13.8%to 15.5%.Extended medium-temperature preheating time in the heat pump slightly reduces system CO₂ purity and recovery rate.When preheating time decreases from 3 h to 1 h,purity and recovery rate are reduced by merely 0.03%and 0.48%respectively,while regeneration heat consumption can be lowered by 0.21 GJ·t^-1.The research further constructs a full-scale steady-state model of a coal-fired power plant integrated with adsorption carbon capture and heat pump systems,and forms a plant-wide energy-mass match method for adsorption carbon capture based on condenser,flue gas,and compression waste heat recovery.At conditions of 2.8 GJ·t^-1regeneration heat consumption and 90%recovery rate,the stepped heating scheme utilizing an absorption heat pump to recover condenser waste heat reduces the entropy generation of the regeneration process from 191.0 k J·K^-1·s^-1 to 126.7 k J·K^-1·s^-1,while lowering the power plant efficiency penalty to 6.50%.By further optimizing steam extraction locations and integrating flue gas and multi-stage compression waste heat recovery,the efficiency penalty can be further reduced to 5.06%.This study develops a dynamic system integrated with adsorption-based carbon capture and a coal-fired power plant and establishes an operational scheduling strategy for the adsorption carbon capture system based on power plant output load.Under variable load conditions,the system demonstrates an average regeneration heat consumption range of 2.1-2.2 GJ·t^-1.Increasing the number of adsorption beds operating under flexible conditions leads to higher regeneration heat consumption,whereas transitioning flexibly operated beds to normal operation reduces heat consumption—primarily due to decreased net regeneration capacity resulting from lower steam temperatures during low-load regeneration.Both increasing the number of beds in flexible and normal operation states reduces the system specific coal consumption,with scheme 7-1-0 achieving the minimum specific coal consumption of0.054 kg_coal·kg_CO2^-1.Economic analysis indicates that the levelized cost of carbon capture for absorption-based and adsorption-based systems under critical scale conditions can be reduced to$50.9 USD·t_CO2^-1 and$35.9 USD·t_CO2^-1,respectively.When peak-shaving capacity is insufficient to meet capture energy demands,requiring additional electricity and steam,the capture costs for absorption and adsorption systems slightly increase to$54.0 USD·t_CO2^-1 and$36.7 USD·t_CO2^-1,respectively.更多还原