Boiler flue gas solar energy storage

How efficient is a thermal storage system?

The equivalent round-trip efficiency of the entire process is 85.17%, which is a high level for energy storage systems. The efficiency is achieved because of the appropriate match between the heat sources and the thermal storage media. To illustrate the thermal performance of the integrated system, an exergy flow Sankey diagram is shown in Fig. 7.

How is heat stored in a thermal power system?

The excess heat of the thermal power system is stored by the heat exchange between the heat sources (i.e., steam and flue gas) and molten salt. During the heat exchange between the steam and molten salt (Fig. 6), the molten salt is heated from 240.0 °C to 380.0 °C as steam is cooled from 600.0 °C to 311.0 °C.

Do thermal power plants need thermal energy storage?

Thermal power plants are required to enhance operational flexibility to ensure the power grid stability with the increasing share of intermittent renewable power. Integrating thermal energy storage is a potential solution.

How to calculate exergy efficiency of molten salt thermal storage?

The exergy efficiency of molten salt thermal storage is calculated as follows: (13) η ms = ∆ E ms E hs × 100 %, where ∆ E ms is the exergy absorbed by the molten salt, kW; and E hs is the exergy released by heat sources, kW. During the discharging process (Fig. 5), the heat stored in molten salt thermal storage will discharge back to the feedwater.

Does flue gas temperature affect the efficiency of selective catalyst reaction (SCR)?

Although the enhancement of flue gas temperature affects the efficiency of the selective catalyst reaction (SCR) system, the flue gas temperature of 392.0 °C is still in the range of catalyst operational temperature (320–400 °C) and does not destroy the activity of catalyst.

What temperature does feedwater enter the boiler water wall?

As shown in Fig. 6, the feedwater is heated from 190.1 °C to 310.5 °C as molten salt is cooled from 426.5 °C to 240.0 °C. As a result, the temperature of feedwater entering the boiler water wall increases to 328.2 °C, but it is still significantly lower than the critical temperature of 374.2 °C.