分布式燃气–蒸汽联合循环供能系统热经济性分析

Thermo-economic Analysis on Gas-steam Combined Cycle-based Distributed Energy Supply System

动力循环参数热力学分析是系统参数配置、系统设计及变工况分析的基础。以既有典型航改型、工业型和114MW容量以下的燃气轮机构成的分布式燃气?蒸汽联合循环供能系统为研究对象,结合实际联合循环装置的设计参数,获得余热锅炉?汽轮机发电效率与透平排气温度之间的经验耦合;提出适合分布式燃气?蒸汽联合循环供能系统的热经济分析参数和分析模型;基于循环分析和热分析的方法获得系统诸设计参数对供能系统设计性能的影响规律。研究表明:引入抽汽做功不足单位系数的概念,可获得综合热效率的简明且物理意义清晰的表达式;当设计热电比及供热参数一定时,综合热效率最佳压比可认为与联合循环效率最佳压比相等;供热/冷蒸汽品位越低,则供能系统综合热效率越高;分布式燃气?蒸汽联合循环供能系统电价期望值高,提高燃气透平进气温度是改善供能系统热经济性的重要方向。研究可作为系统变工况性能分析及电/热/冷价与天然气价格联动机制的工作基础。

Thermodynamic analysis on power cycle parameters is generally the basis of parameter configuration,system design and off-design performance.Based on the design parameters of the practical distributed energy supply systems with gas-steam combined cycle,consisting of typical industrial type,aeroengine modified-type and heavy-duty gas turbines below 114 MW capacity,the empirical coupling relation between the power efficiency of bottom cycle and the exhaust temperature of turbine was summarized.The thermo-economic analysis parameters and model were proposed suitably for the energy supply system.Using the proposed method,the influence of design parameters on the design performance of the energy supply system was obtained.It concludes that,the concept of unit power deficiency coefficient by extraction steam obtains a concise and meaningful expression of comprehensive thermal efficiency.At a given designed heat/power ratio and heating parameters,compressor optimal pressure ratio at the maximum comprehensive thermal efficiency is considered equal to that at the maximum power efficiency of combined cycle.The system has a higher comprehensive thermal efficiency in the case of a lower grade of steam for heating/cooling.The expectation value of electrical power price of the distributed energy supply system is relatively higher.Improving turbine inlet gas temperature is an important direction for enhancing the thermal economy of the system.This research presents a basis for the off-design performance analysis and the price linkage mechanism between power/heating/cooling and natural gas.