A molten salt heat storage system and heat exchange method for solar thermal power plants

Abstract

The present invention provides a molten salt heat storage system for a solar thermal power station, the molten salt heat storage system comprising: a high temperature molten salt storage tank (1), a mixer (7), a preheater (4), Low-temperature molten salt storage tank (2), mirror field (13) and multiple pipelines; the technical solution provided by the present invention uses a mixer to mix the high-temperature molten salt in the high-temperature molten salt storage tank with the low-temperature molten salt at the outlet of the steam generator , which increases the temperature of the molten salt entering the inlet of the preheater and reduces the risk of freezing of the preheater due to factors such as load adjustment and the environment; The salt is mixed, which increases the temperature of the molten salt flowing into the mirror field pipeline, increases the margin for safe operation of the molten salt in the mirror field circuit at night, and reduces the risk of molten salt freezing in the mirror field circuit. The technical scheme provided by the invention reduces the self-consumption power for heat tracing of a photothermal power plant and improves the economic benefits of the power plant.

Description

technical field [0001] The invention belongs to the field of solar thermal power generation, and in particular relates to a molten salt heat storage system used in a solar thermal power station and a heat exchange method thereof. Background technique [0002] Solar high-temperature thermal power generation technology is an important direction for large-scale utilization of solar energy, and it has far-reaching significance for human beings to solve problems such as fossil energy crisis and air pollution. The working fluids used in solar high-temperature thermal power generation include water vapor, molten salt, air, heat transfer oil, liquid metal and other heat transfer media. Among them, due to the fluctuation and discontinuity of sunlight, the solar thermal power generation system must have a large-scale heat storage system in order to continuously and stably generate electricity. Molten salt has the characteristics of high operating temperature, wide temperature range, ...

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Problems solved by technology

[0003] The traditional solar trough photothermal power generation system is limited by the safe use temperature of the heat transfer oil, so the system operating temperature cannot exceed 400°C, which affects the overall operating efficiency of the system; Requirements, the steam generator often deviates from the design operating point to operate, which may easily cause the temperature of the molten salt outlet of the steam-water side preheater to be too low, and the preheater may have the risk of freezing and blocking; during night operation, due to the influence of external ambient temperature and other factors, As a result, the temperature of the molten salt flowing out of the low-temperature molten salt storage tank is too low in the mirror field circuit, which is prone to freezing accidents

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