Development and optimization on separated structure steam generator based on a new thermal design model

Adopting the traditional LMTD method to design the SS-SG (Separated Structure Steam Generator) usually leads to a larger deviation due to drastically change in physical properties of flue gas with changing temperature. This makes the consumption of steel tubes and power energy during both the manufacturing and operation processes increase. As an exploratory investigation, a novel thermal design model was developed with the idea of micro-element superposition and validated against the experiment herein. It revealed that the maximum absolute deviation between prediction and experiment was less than 2.5%, which outperformed a lot compared to the traditional method. As an application case, this model was used to design an actual steam generator in this study. The design results showed that the steel tube consumption can be reduced by 27.19%, while the power energy consumption can be saved by 11.45% for long-term operation. Using the proposed model, the effect of operating conditions on thermal performance of the steam generator was discussed. It indicated that the increase in the inlet temperature and mass flow rate of flue gas, as well as the operating pressure, generally weakens the comprehensive thermal performance indexes PEA and PEB. Besides, this novel model can also be combined with an intelligent algorithm to perform structure optimization. For this case, compared to the original structure, the total cost can be further decreased by 17.57% with the obtained optimal structure from an economic point of view. It is of great significance to improve the economics of recovering flue gas waste heat.