Selection of electric heating system for photothermal power plant

Published on:

2023-02-18 10:19

Photothermal energy production (solar thermal power generation) is a system that converts solar energy into thermal energy and generates electricity through the conversion process of thermal work. In addition to a thermal energy conversion system similar to conventional thermal energy, solar thermal energy also has a light-to-heat conversion process, which is a connected light-to-heat-work system.

Whether the heat carrier of a solar thermal power plant is water, heat transfer oil or molten salt, there is a risk of freezing to varying degrees when flowing through pipelines, instruments and other equipment. Cause additional damage to the safe operation of the system. Especially in the north-western region of my country, the operating conditions of solar thermal power plants are relatively harsh, with the lowest temperatures below minus 40C, and the risk of freezing and blocking the system is extremely high. Because molten salt has a high freezing temperature, once the temperature reaches the freezing point of the molten salt, it is very easy to cause the pipeline to freeze and block, and even lead to paralysis of the entire system. In order to ensure the safe and stable operation of the solar thermal power plant, liquid salt media circulation equipment such as storage tanks, piping, valves and heat exchangers should generally be equipped with electric heating devices.

Electric heating in the traditional area is mainly used for pipe insulation and anti-freeze protection The working temperature of the electric heating is usually around 60-200 °C. However, due to the high requirements for the operating temperature of solar thermal power plants, the electric heating temperature should be higher than 300 ° C, and in some areas even higher than 500 ° C is required, and can work stably for a long time at this temperature, therefore, higher requirements are put forward to the reliability of the electric heating system.

As a result of continuous improvement and validation of the molten salt electric heating project in the photothermal industry, it has been finalized that the product suitable for heating with molten salt is a mineral insulated alloy 825 sheathed heating cable.

This type of mineral insulated heating cable has high safety performance and long service life. It is a new product with excellent economic performance in China. It can be used not only as an electric heating element, but also as an electric heating element. Since all mineral insulated heating cables are made of heat-resistant metals and inorganic insulating materials, they have incomparable advantages over other heating cables or plastic-bonded heating belts such as high mechanical strength, long service life and high operating temperature. Resistance to solar radiation, etc.

In solar thermal power plant projects, electric heating is a key auxiliary system for heat collection and storage systems. The electric heating system uses an accurate and optimized design, which makes it possible to compensate for the thermal losses of pipelines and equipment into the environment by converting electrical energy into thermal energy, and to prevent solidification and crystallization of heat carriers such as molten salt and heat transfer oil. Piping and equipment, as well as freezing protection of the hydraulic fluid at 0 °C to ensure fluid flow in the process system. A well-designed, reliable product and more strictly installed electric heating system can not only make the heat collection and accumulation process of thermal power plants safer and more stable, but also avoid large losses caused by freezing.

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