Design of electric heating of molten salt storage tank at photothermal power plant

Published on:

2023-02-23 10:58

There are usually three types of electric heating systems, namely electric heating, steam heater and hot air heater. Generally, the cost of an electric heating system is relatively low, the cost of a steam heating system is relatively high, and the cost of a hot air heating system is in the middle. The principle of electric heating system is relatively simple. The main equipment used is heating cable. The heating cable uses electricity as an energy source.

The electric heating system consists of electric heating wire, heating wire accessories, distribution box, heating control and detection system, and installation accessories.

The outer shell material of the electric heating cable is generally a stainless steel or nickel-based material, which has good corrosion resistance, can resist pitting corrosion, chloride corrosion, acid corrosion, and can be used in high temperature conditions for a long time. Time. Common electric heating outer shell materials include stainless steel 304/306/321 and 347, etc. D., as well as high quality 310S stainless steel, Inconel 600 and Inconel 825, etc. D. The quality of stainless steel mainly depends on the composition of the material itself and the improvement of the heat treatment process performance.

Generally, highly compressed oxides are used to insulate resistance wires, and the voltage can reach 600 V. A fully closed shell protects magnesium oxide from steam pollution and increases the reliability of electric heating. Faced with resistive wires of different materials and specifications, people should choose according to the output power of electric heating. The wire of the heating cable at the non-heating end is pulled outward from the high-temperature heating equipment, and the length of the cold-end wire is determined according to factors such as the insulation thickness and location of the junction box.

The electric heating system is a new type of heating device combining the preheating of the molten salt tank and the heating of molten salt in a single device. Electric heating is arranged on the bottom and wall of the tank, and the salt melt is heated by electric heating when the unit is not working. During the first salt injection preheating, the electric heating system heats the tank wall, cools the tank wall with an external storage tank circulation fan and simultaneously heats the air, and also uses heated hot air to budget the tank top. And the bottom of the tank.

The electric heating device includes an electric heating and thermocouple of the bottom and wall of the tank, a circulation fan, an air duct outside the tank, an air tank, a fixed spiral nozzle and a spiral nozzle, etc. The electric heating partitions of the bottom and the wall of the tank are arranged and controlled independently of each other, and the temperature in each partition is controlled by thermocouples. Before preheating, turn on the external circulation fan of the tank, make the tank body metal through the air intake pipe and nozzle, and control the rate of increase in the temperature of the tank wall and the temperature difference between the different parts, adjusting the air circulation rate in the pipes and the amount of electric heating. Finally, the temperature of the metal walls of the tank is heated to a calculated value. When the device is turned off to heat the molten salt, the electric heating within the appropriate height range is turned on according to the liquid level of the molten salt to maintain heat dissipation and heat the molten salt.

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