单压过热蒸汽余热锅炉抽汽运行的解析特性

Analytical Characteristics of HRSG With Steam Extraction

抽取余热锅炉的部分饱和蒸汽供吸收式制冷或供热是常见的余热利用方式之一。在单压过热蒸汽余热锅炉变工况解析解的基础上,推导出其抽汽运行特性的近似解析解,讨论抽汽运行的典型解析特性。定性分析和解析结果表明,抽汽后余热回收率的变化甚微,接近点温差和节点温差略有增大,但过热器的热端端差迅速下降。近似解析解与数值解对比表明,蒸汽产量的解析解在工况变动较大的范围内是可靠的,过热蒸汽温度的解析解适用于设计工况附近和饱和蒸汽抽汽量不大的情况,基于数值结果给出的过热蒸汽温度拟合式则在工况变动较大的范围内也适用。该解析特性对分析余热锅炉冷、热、电并供的变工况有理论意义,也便于进行初步工程分析、核算。

Saturated steam extraction from the evaporator of heat recovery steam generator （HRSG） is often applied in various industries. Based on the analytical solution for off-design performances of superheated steam HRSG with single pressure, an approximate analytical solution for the performances of HRSG with steam extraction was deduced and the typical off-design performances were further discussed. Quantitative and qualitative analysis accordantly shows that, steam extraction has little influence on heat recovery rate; however, the approach point temperature difference and pinch point temperature difference rise slightly with the steam extraction, superheater approximate while warm end temperature difference of drops greatly. Comparison between the computational analytical solution and more accurate solution indicates the steam production analytical solution is reliable in various off-design conditions while the steam temperature obtained by analytical solution is only available for the case of near-design conditions. However, the presented regression solution for steam temperature is applicable in wide off-design conditions. The analytical off-design performances of HRSG with steam extraction are meaningful for the theoretical research and are suitable for primary engineering analysis also.