当前我国能源供给形势严峻、环保压力增大，深入开展节能减排工作显得尤为迫切。工业余热利用是推进节能减排的重要环节，其中250℃以下低温余热的回收利用率亟待提高。有机朗肯循环（ORC）技术作为低温余热发电利用的有效途径之一，经济效益逐渐凸显，但其应用因国内有机工质膨胀机技术尚未发展成熟而受到限制。鉴于有机朗肯循环系统的应用价值和透平技术的重要性，本文进行低温有机朗肯循环及其透平的研究，并结合企业试验验证和推广ORC技术的需求，开展500kW级ORC试验系统及其有机工质向心透平样机的设计与研究。本文建立有机朗肯循环设计与分析系统，研究热力循环参数对有机朗肯循环系统性能的影响；研究不同温度等级低温余热的ORC系统适宜工质，以及工质热物性对循环热力性能、经济性、环境友好性、透平设计的影响。针对某炼化企业120万吨/年重整抽提装置98~215℃的5股温度不等余热热源，按照梯级利用余热温度等级和综合配置能量的方法，提出单工质R141b分流30.3%高温蒸发、60.9%低温蒸发的双参数ORC余热发电系统方案，在保证系统输出功率与分别利用5股余热方案相当的条件下，实现发电系统的简单紧凑化，并有效降低成本。根据有机工质透平膨胀比高、总焓降小，而有机工质分子量小、声速低的特点，本文研究有机工质向心透平的气动设计方法，建立了向心透平的一维气动设计与性能三维数值分析系统。针对500kW级ORC试验系统的热力循环，进行以R123为工质的向心透平的气动布局设计优化，结合预测的透平变工况性能，综合评估和优选气动设计；采用三维数值模拟方法验证透平气动设计，分析透平运行性能和内部三维流动特性，数值模拟结果与气动设计基本一致。针对向心透平内强激波和局部分离流动，本文采用NURBS技术参数化控制型线、利用三维数值计算方法分析透平气动性能、结合遗传算法和序列二次规划算法对向心透平喷嘴和叶轮进行气动优化研究。结果表明优化的喷嘴二维叶型和积叠线使透平效率有所提高，优化的子午流道消除了叶轮吸力面的分离流动，数值模拟的透平效率累计提高约1.05个百分点，采用后弯式叶轮亦进一步改善了透平内部的局部流动。结合向心透平的性能曲线，研究500kW级ORC试验系统的变工况热力性能，为试验台的运行控制和试验提供数据。目前向心透平已制造完毕，蒸汽冲转测试表明向心透平振动约20μm。试验台正在建设中，预计2014年初进行运行试验，试验结果可为ORC系统及有机工质向心透平技术的应用提供重要数据支撑。

As the shortage of energy supply, the energy saving work is in desperate need. The utilization of the industrial waste heat is an important step to the energy saving work, especially for the waste heat with temperature below 250℃. As one effective way of the waste heat recovery for power generation, the Organic Rankine Cycle (ORC) system gradually shows a remarkable economy benefits, but is seldom applied due to the immaturity of the domestic ORC expander technology. Given the significance of the ORC system and its turbine technology to the waste heat recovery, this dissertation does the research and design of the low-temperature ORC system and its turbine. Then the 500kW class ORC testing system and its radial turbine are studied and designed according to a certain enterprise’s demand of validating and popularizing the ORC technology. This dissertation establishes the design and analysis system of the ORC system, for studying the influence of the cycle parameters on the ORC thermal performance. This dissertation also studies the selecting of the suitable organic working fluids for the low-temperature waste heat with different temperatures, and the influences of the working fluids’ thermal properties on the ORC thermal efficiency and system economy, the organics’ environmental impact and the turbine design. According the demand of recovering the five waste heat sources with their temperatures ranging from 98℃ to 215℃ from a 1.2 million ton/a reforming and extraction unit, the waste heat recovery system using ORC is studied with the principle of the energy gradient utilization and the comprehensive distribution of the heat sources. The ORC system using single working fluid but with two evaporation section was proposed to make the system simple and compact as well as reduce the cost, while ensuring the system output power. In the proposed ORC system for the reforming and extraction unit, R141b is used and 30.3% of the mass flow rate is evaporated at the high temperature and 60.9% is evaporated at the low temperature. According to the characteristics of the organic turbine: high expansion ratio and low enthalpy drop, and the characteristics of the organic working fluid: small molecular weight and low speed of sound, the aerodynamic design and performance prediction method of the radial turbine in the ORC system are studied, and an one-dimensional design system and a three-dimensional (3D) numerical analysis system for the turbine performance are established. The 500kW-class model turbine for the ORC test rig with R123 as working fluid is designed, combining the analysis of the predicted turbine performance. The radial turbine’s aerodynamic design and performance are validated and analyzed by the 3D numerical simulations. The numerical simulation results agree well with the one-dimensional design. For the appearance of the strong shock wave and local separations, this dissertation uses NURBS curve technology to control the profile shape, uses 3D numerical simulation to analyze the aerodynamic performance, and utilizes the combination of genetic algorithm and sequential quadratic programming to optimize the turbine nozzle and impeller. Results show the increase of the turbine efficiency, and the inhibition of the separation zone on the impeller suction side. The turbine efficiency after the optimization increases by about 1.05 percent. The backward impeller further improves the flow field.With the performance map of the radial turbine, the design and off-design thermodynamic performance of the 500kW-class ORC test rig is studied, for the purpose of providing reference data to the test rig running and controlling. The turbine has been manufactured, and its vibration test using the steam is 20μm. This test rig is under construction, and experiments are expected to start in the early 2014. The test results are of crucial use for the industrial application of the ORC system and its turbine technology.