Сравнение эффективности кожухотрубчатых и пластинчатых подогревателей конденсата

Abstract

В статье приведены результаты оптимизационных вычислительных экспериментов, оценивающих эффективность применения пластинчатых и кожехотрубчатых теплообменников в качестве подогревателей конденсата паротурбинной установки. Нагрев конденсата производится водой, цикрулирующей в контуре охлаждения колосниковой решетки парового котла, работающего на лузге подсолнечника. Также проанализированы оптимальные скорости сред для обоих типов теплообменников. Рассмотрены ограничения, накладываемые конструкцией аппаратов.The article presents the results of optimization computational experiments, which evaluated the effectiveness of the use of plate and shell and tube heat exchangers as feedwater heaters. The condensate is heated by water flowing through E35-3.9-440 steam boiler fire-grate cooling circuit. This boiler operates on sunflower husk. The capacity of bioelectric power stations, for which the computational experiment was done, varies from 2 to 27 MW. The steam pressure of the turbine inlet is 40 bar, the temperature is 440 °C. The heater in question is located on the main condensate line before the deaerator. It was done the comparison of the effectiveness of shell and tube and plate apparatus for this application. The optimal fluid velocities for both types of heat exchangers were also analyzed. The limitations of apparatuses design are considered. The computational experiment was done according to the "total costs" optimality criterion, only the design parameters of the heat exchangers were optimized. The experiment shows that the effectiveness of plate heat exchangers is higher in this case. An interesting dependence has also been recovered that relates the water temperature in the plate heat exchanger channels and its optimal velocity. The higher the water temperature, the higher its optimal velocity, which is associated with a decrease of viscosity when increasing the water temperature. This dependence is quite significant, and this fact makes it possible to consider that it is necessary to do optimization when designing this type of heat exchangers.