超临界二氧化碳发电系统研究进展

发电系统是新能源发电的热点研究方向之一,本文系统地论述了该发电系统的原理和特点、发展历程、前沿技术和应用前景,指出先进密封技术、高温高压回热器设计技术和闭式循环系统控制技术等为目前存在的技术难点,并从循环机理分析、系统总体设计和关键部件设计等方面对未来发展趋势进行展望。     

超临界二氧化碳循环应用于火力发电的研究现状

超临界二氧化碳动力循环(sCO₂循环)系统简单、结构紧凑、效率高,可与采用化石燃料燃烧方式的热源结合,形成先进的火力发电系统。sCO₂循环有间接加热和直燃加热两种方式,前者可采用燃煤锅炉间接加热获得热能,后者可采用燃气直接燃烧获得热能。基于对当前国内外的研究现状的文献调研,可以得出结论:sCO₂循环可应用于火力发电,并有望开发大型的清洁、高效火力发电系统,突破传统火力发电技术发展瓶颈。     

煤基直接加热式超临界二氧化碳动力循环系统建模及性能分析

利用Aspen Plus软件分别构建了煤气化直接加热式和煤直接燃烧式sCO2动力循环系统模型,对空气分离装置(ASU)子系统、热力发电子系统和烟气净化压缩子系统进行耦合计算,并分析各主要参数对整体循环性能的影响规律.结果 表明:对于煤气化sCO2循环,在透平入口1150℃/30 MPa的参数条件下,系统净效率可达40.67％,同时可实现接近100％的碳捕集;在考虑系统整体能耗后,ASU出口O2存在最佳纯度,当O2纯度由95％增加至99.5％时,系统净效率由40.16％升高到40.67％;在相同关键循环参数条件下,由于取消了煤气化及合成气压缩装置,煤直接燃烧式sCO2循环的系统净效率相比煤气化直接加热式循环提高了7.54％.     

Carbon Dioxide Mineralisation and Integration with Flue Gas Desulphurisation Applied to a Modern Coal-Fired Power Plant

For Finland, carbon dioxide mineralisation was identified as the only option for CCS （carbon capture and storage） application. Unfortunately it has not been embraced by the power sector. One interesting source-sink combination, however, is formed by magnesium silicate resources at Vammala, located -85 km east of the 565 MWe coal-fired Meri-Pori Power Plant on the country＇s southwest coast. This paper assesses mineral sequestration of Meri-Pori power plant CO2, using Vammala mineral resources and the mineralisation process under development at Abo Akademi University. That process implies Mg（OH）E production from magnesium silicate-based rock, followed by gas/solid carbonation of the Mg（OH）2 in a pressurised fluidised bed. Reported are results on experimental work, i.e., Mg（OH）2 production, with rock from locations close to Meri-Pori. Results suggest a total CO2 fixation capacity -50 Mt CO2 for the Vammala site, although production of Mg（OH）2 from rock from the site is challenging. Finally, as mineralisation could be directly applied to flue gases without CO2 pre-capture, we report from experimental work on carbonation of Mg（OH）2 with CO2 and CO2-SO2-O2 gas mixtures. Results show that SO2 readily reacts with Mg（OH）2, providing an opportunity to simultaneously capture SO2 and CO2, which could make separate flue gas desulphurisation redundant.     

超临界二氧化碳布雷顿循环研究进展

超临界二氧化碳布雷顿循环的循环效率高(可达50％)、系统结构紧凑、压缩耗功少、降本潜力大,可与化石能源、核能和太阳能等多种形式热源相结合,应用前景广阔.从关键部件和循环系统的角度综述了国内外超临界二氧化碳布雷顿循环在热源设备、动力设备、回热设备、冷却设备以及设计优化等方面的研究进展,分析了超临界二氧化碳关键部件的实验测...     

1000MW超超临界机组锅炉运行测试

针对某火力发电厂2号机组的锅炉热效率、NOx排放及空气预热器漏风率进行了测试,检验锅炉能否达到供货商对其提供产品所作的性能保证值。结果显示其锅炉效率和NOx排放量达到性能保证值,但空气预热器的漏风率略高于其保证值。     

General Design and Thermodynamic Analysis of a Supercritical Carbon Dioxide Cannon

This paper presents a new supercritical carbon dioxide(SCO₂)cannon based on the carbon dioxide(CO₂)’s thermodynamic cycle under constant volume.First,Virial equation and NIST database are applied to formulate SCO₂’s property and analyze the thermodynamic cycle,which is aimed to get the optimization equation using the cannon’s exit velocity as objective function.Then the cannon’s structural parameters,such as diaphragm thickness and barrel length,and CO₂’s filling mass,are optimized.Finally,the flow field and velocity’s change during the launch process is performed with FLUENT.In field test,the ultra-high pressure sensor and ultra-high speed camera are used to measure the pressure distribution along the barrel’s axial direction and the projectile’s exit velocity under different conditions.The results show that all the performance indexes meet the design requirement.The innovative SCO₂cannon in this paper has obvious advantages such as high safety,low cost and fast loading,which can be applied in many situations such as disaster relief,peacekeeping and anti-terrorism.Moreover,the unique energy storage method and thermodynamic design ensure its subsequent development.     

超临界二氧化碳环境中耐热材料的腐蚀行为研究

选取5种典型耐热材料T91、VM12、Super 304H、Inconel 617和Sanicro 25为实验材料,在600℃、15 MPa条件下进行超临界二氧化碳腐蚀实验.通过分析天平获得耐热材料增重量变化;利用拉曼光谱仪、X射线衍射仪和辉光放电光谱仪对耐热材料表面腐蚀产物进行物相和成分表征;利用电子显微镜进行表面和断面形貌观测,最后分析耐热材料的腐蚀行为.结果表明:T91和VM12符合抛物线型.腐蚀动力学规律,Super 304H、Inconel 617和Sanicro 25则增重量不明显,没有明显规律;增重量与耐热材料的Cr质量分数呈反比关系;在高温超临界二氧化碳环境中耐热材料发生了氧化和碳化反应;T91和VM12没有贫Cr现象,而Super 304H、Sanicro 25和Inconel 617则具有明显的贫Cr区域,且贫Cr区域厚度由小到大依次为:Inconel 617＜Sanicro 25＜Super 304H.     

Simulation of Supercritical Carbon Dioxide Fracturing in Shale Gas Reservoir

In order to fracture shale gas reservoir with carbon dioxide as the working fluid,laboratory experiments were firstly conducted to measure the influence of carb...     

A New Supercritical Carbon Dioxide Brayton Cycle with High Efficiency

Designing new and efficient heat engines and increasing the efficiency of previous ones is one of the researchers’ interests in the field of thermodynamics. In this regard, what is mainly concerned is to design a cycle with the positive features of previous cycles, such as less pollution, and higher power‐to‐weight ratio and efficiency. One of these cycles is the supercritical carbon dioxide cycle (SCDC). The main goal of this research is designing a highly efficient SCDC with pessimistic and relatively optimistic efficiencies of 45% and 47%. This paper includes the complete first law analysis of the designed cycle, designing and discussion of efficiency improvement methods and comparison of SCDC with other power cycles. The sensitivity of the cycle efficiency to some important parameters has also been studied.     

超临界二氧化碳透平叶根轮槽结构优化设计

针对10 MW超临界二氧化碳透平机组,对其T型叶根轮槽型线进行优化,通过理论分析得到优化后叶根轮槽接触面的变化角,采用有限元法对优化前后T型叶根轮槽的应力分布情况进行了比较;同时分析了叶片预扭机理和转子变形量的影响因素,提出一种优化T型叶根菱形中间体结构的方法.结果 表明:优化后的轮槽峰值应力比优化前略有提高,叶根的峰...     

基于超临界CO2循环的地热与太阳能混合系统研究

超临界CO₂循环可以耦合较低温度的地热和较高温度的太阳能热组成混合热源发电系统。相比能量分析方法,火用分析方法更便于分析混合系统对提高能量利用率的作用,以及识别造成可用能损失的设备和过程。115℃地热和200℃地热分别与采用槽式聚光集热技术的太阳能热组成混合热源,构成简单回热超临界CO₂循环。分析结果表明：混合系统的火用效率比单纯太阳能热的循环系统提高了5% ~ 10%;太阳能聚光集热器的?损失最大,占80%以上,其次是除预冷器以外的各类换热器以及透平;相比之下,压缩机和预冷器的火用损失较小。减少?损失的关键是提高太阳能聚光集热器和换热器的性能,包括提高集热管运行温度,以及提高换热器效能。     

Phase Prediction of Supercritical Carbon Dioxide and its Application in Fracturing Oil Wellbores

In recent oil and gas exploration, the most reservoirs are low permeability with abundant reserves. Conventional mining of low permeability reservoir is commonly utilizing the hydraulic fracturing technology, whereas, it encounters various technical issues, such as clay expansion and water lock damage. Using the fluid of supercritical carbon dioxide(S-CO_2) to exploit the low permeability oil and gas reservoirs is attracting more attention. The implementation of S-CO_2, without liquid phase, can help avoid the aforementioned problems. Nevertheless, the phase change of CO_2 during fracturing is complicate, and it is difficult to accurately predict the CO_2 phase transition. In this work, first, the physical properties of S-CO_2 were analyzed by the Span-Wagner model and Vesovic model. Next, S-CO_2 was applied to a typical oilfield, and an unsteady coupling model of heat transfer and pressure drop was developed. Then the staggered grid method and iteration procedures were used for numerical solutions, and the temperature and pressure distributions of wellbores were investigated. The results indicate that the temperature control of a wellbore is the key to the phase prediction of S-CO_2; CO_2 within the single-diameter pipeline below 2300 m can maintain the supercritical state, while CO_2 within the stepped pipeline can maintain the supercritical state at the depth of 2280 m. Moreover, compared with the single-diameter pipeline, the bottom pressure of the stepped pipeline is lower and the bottom temperature is higher. By analyzing the flow and heat transfer of S-CO_2 in the wellbores, the phase state of S-CO_2 was well predicted, which is helpful to improve the exploring performance of low permeability oil and gas reservoirs.     

超临界二氧化碳扇贝阻尼密封动力稳定性研究

为研究超临界二氧化碳(Supercritical Carbon Dioxide, SCO₂)扇贝阻尼密封在不同工况下动力稳定性,建立SCO₂扇贝阻尼密封数值计算模型,分析进口压力、温度及转速对SCO₂扇贝阻尼密封动力特性及泄漏特性的影响。结果表明：直接复合刚度随涡动频率增加由正变负;交叉复合刚度随进口温度、压力增加而减小,随转速增加而增大;SCO₂扇贝阻尼密封的有效阻尼随进口温度、转速增加而减小,随进口压力增加而增大,进口压力为8.1 MPa时有效阻尼约为7.7 MPa时的1.7～2.9倍;扇贝阻尼密封直接复合刚度、有效阻尼整体上大于迷宫密封,稳定性高于迷宫密封,但泄漏量略高于迷宫密封。     

高压CH4-CO2重整制合成气研究进展

在研究国内外关于高压下CH4-CO2重整制合成气文献的基础上,讨论了高压下CH4-CO2反应热力学、反应特性及反应机理,提出了高压炭催化CH4-CO2重整的研究方案。     

Heat Transfer Characteristics of Printed Circuit Heat Exchanger with Supercritical Carbon Dioxide and Molten Salt

Molten salt and supercritical carbon dioxide (S-CO_2) are important high temperature heat transfer media,but molten salt/S-CO_2 heat exchanger has been seldom reported.In present paper,heat transfer in printed circuit heat exchanger (PCHE) with molten salt and S-CO_2 is simulated and analyzed.Since S-CO_2 can be drove along passage wall by strong buoyancy force with large density difference,its heat transfer is enhanced by natural convection.In inlet region,natural convection weakens along flow direction with decreasing Richardson number,and the thermal boundary layer becomes thicker,so local heat transfer coefficient of S-CO_2 significantly decreases.In outlet region,turbulent kinetic energy gradually increases,and then heat transfer coefficient increases for turbulent heat transfer enhancement.Compared with transcritical CO_2 with lower inlet temperature,local heat transfer coefficient of S-CO_2 near inlet is lower for smaller Richardson number,while it will be higher for larger turbulent kinetic energy near outlet.Performance of PCHE is mainly determined by the pressure drop in molten salt passage and the heat transfer resistance in S-CO_2 passage.When molten salt passage width increases,molten salt pressure drop significantly decreases,and overall heat transfer coefficient slightly changes,so the comprehensive performance of PCHE is improved.As a result,PCHE unit with three semicircular passages and one semi-elliptic passage has better performance.     

中国燃煤发电节能技术的发展及前景

我国一次能源结构决定了发电以煤电为主的基本格局,当前国内火力发电行业需要解决的两大突出问题是高能耗和严重的环境污染。2009年全国发电机组平均供电煤耗341g/(kW.h),高于330g/(kW.h)的国际平均水平。大力发展新型高效节能性火力发电技术,对进一步提高我国火力发电机组的发电效率,减少燃煤大气污染物排放具有十分重要的意义。发达国家正积极发展更高参数的超超临界火力发电技术(600℃/700℃),我国也把"超(超)临界燃煤发电技术"列入"863计划"。可以预见,在我国近中期电力事业的发展中,会把发展更高参数的超临界技术作为火电建设的主要方向。IGCC发电技术是未来煤炭能源系统的基础,被公认为是世界上最清洁的燃煤发电技术。随着煤气化技术和燃气轮机技术的不断发展和进步,IGCC将朝着大容量、高效率、低排放的方向发展。大型直接空冷发电技术是解决我国西北部富煤贫水地区火力发电的有效手段,以2×600MW机组为例,空冷机组比湿冷机组节水约80%左右。通过对火力发电机组各系统的集成与优化,可在现有超超临界机组技术不变的情况下,最大限度地利用余热回收,提高整个机组的发电效率,从而降低煤耗,实现机组在运行过程中的节能。     

叶顶间隙对超临界二氧化碳向心透平性能的影响

为探究叶顶间隙对超临界二氧化碳向心透平机性能的影响,以某超临界二氧化碳向心透平为例,设置不同叶顶间隙,利用计算流体动力学(CFD)仿真软件进行数值模拟。结果表明:当径向间隙等于轴向间隙时,间隙尺寸在0.1~0.5 mm范围内,叶顶间隙与叶轮出口叶高的比值每增大1%,总-静效率降低1.07%左右。当径向间隙不等于轴向间隙时,轴向间隙每增大1%,总-静效率降低0.146%左右,径向间隙每增大1%,总-静效率大约降低0.362%;径向间隙对于透平性能的影响远大于轴向间隙,叶顶间隙在0.1~0.5 mm范围内时,径向间隙对总-静效率的影响约为轴向间隙的2倍。     

A New Structure of Cooling Wall Tube for Supercritical CO2 Coal-Fired Power Plants

In terms of developing supercritical CO₂(sCO₂) coal-fired power plants,enhancing cooling wall performance is one of significant factors to improve system performance.In this paper,a new cooling wall tube structure is proposed to match the non-uniform heat flux(NUH) with the thermal resistance by changing the cooling wall tube eccentricity.A three-dimensional multi-physical coupling model of cooling wall is constructed to compare the novel structure to the conventional struc...     

大型电厂煤粉锅炉掺烧油页岩的应用研究

为了缓解大型电厂原煤资源紧缺的现状,油页岩可作为其新的替代能源.在分析了煤与油页岩掺烧特性基础上制定了二者掺烧方案,并通过在茂名热电厂680 t/h锅炉上进行实炉掺烧试验,结果表明,在不改变系统和设备结构的情况下,油页岩的最大掺烧量可达40%;掺烧量达30%时锅炉效率变化不大,每kwh的发电成本降低了O.065O元.由此证明存大型电厂燃煤锅炉掺烧适量油贞岩具有町行性、安全性和经济性.