This work investigates the flow and heat transfer on the gas side of a heat recovery steam generator. During the operation of a power plant, off-design conditions that significantly impact the steam generator efficiency, caused by variations in the gas flow, corrosion and fouling of tube walls, may be encountered. In addition, passages around the heat exchanger modules develop along the equipment lifetime, allowing the bypass of flowing gas into zones of the boiler of low heat transfer effectiveness. These issues are here addressed via computational simulations, using a commercial software application for solving the mass, momentum, and energy conservation equations. The boiler geometry and the boundary conditions for the simulations are taken from a real, typical industrial heat recovery steam generator fed by gas turbines exhaust gases. Flow turbulence is modeled using the k-\({\epsilon}\) model, and heat exchanger modules are considered as porous media, through which the exhaust gases flow while supplying heat to the water. The water flow properties are specified from process data. Numerical results for thirteen realistic off-design conditions are compared to those for the boiler normal operation point. It is found that the cases considering deviation of gas to the trapdoors and lateral passages have the greatest impact on the boiler efficiency. Results indicate an efficiency drop from 86% for the base case to 48% for the case with gas deviations. In addition, a reduction in the gas flow or the plugging of the low-pressure economizer tubes may decrease the boiler efficiency by more than 10% points.

这项工作研究了热回收蒸汽发生器气体侧的流动和传热。在发电厂运行期间，可能会遇到因气体流量变化，管壁腐蚀和结垢而严重影响蒸汽发生器效率的非设计条件。另外，围绕热交换器模块的通道沿设备寿命发展，从而使流动的气体绕过锅炉，传热效率低。这些问题在这里通过使用商业软件应用程序来解决质量，动量和能量守恒方程的计算仿真来解决。锅炉的几何形状和模拟的边界条件取自由燃气轮机废气供给的真实，典型的工业热回收蒸汽发生器。k - \（{\ epsilon} \）模型，并且热交换器模块被视为多孔介质，废气在向水供应热量的同时流过。水流量属性是从过程数据中指定的。将13种实际非设计条件下的数值结果与锅炉正常运行点的数值结果进行了比较。结果发现，考虑气体向活板门和侧通道偏离的情况对锅炉效率的影响最大。结果表明，效率从基本情况下的86％下降到有气体偏差情况下的48％。另外，气流的减少或低压节能器管的堵塞可能使锅炉效率降低10％以上。