Selection and application of high temperature molten salt pu

    The molten salt is used for heat storage medium or a heat transfer medium in the solar thermal power station thermal island. Molten salt pump is one of the most critical equipment. Pump’s design, material selection, process and others need rich experience to support. Because the temperature that molten salt pump needs to work normally for a long time is 220 ～550degrees Celsius. The molten salt pump before it works needs to repeated test to verify the performance, so as to avoid bringing serious problems when it is used.
   Structure of molten salt pump is composed of power system, transmission’s system and conveying system. Dynamic system mainly consists of a motor and a motor’s support. And it is the power source of the molten salt pump. Transmission’s system is composed of a main shaft and a bearing bracket. Their function is to complete the power transmission. Motor high-speed operation transformation for the impeller operation can offer power to work that power is used to produce conveying high temperature molten salt. Delivery system mainly consists of conveyor tube that it is used for delivering high temperature molten salt.
    You should analyze the cost of the molten salt at the first before you determine the selection of molten salt pump, such as the types of molten salt, temperature, melt and so on.
    The selection of pump’s material needs high temperature, corrosion resistance, strength and service life. The molten salt decomposition can release gas when it is the high temperature. And the gas has greater corrosion. With Binary Molten Salt for example, operating temperature of molten salt tank power plant and power plant tower of molten salt is not the same. The operating temperature of groove type molten salt heat storage system is 220 ~400 degrees Celsius. According to the temperature of molten salt pump, we can select of 304、316 stainless steel as material temperature. And the temperature of the molten salt tower power plant is in 220 ~550 degrees Celsius. If so, we need to use the 316、347 stainless steel or 718 chromium nickel alloy steel that they can bear higher temperature resistance and corrosion resistance.
    High-speed of molten salt will also cause rapid corrosion of molten salt pump impeller. Corrosion damage rate and medium are directly proportional to the velocity. The higher of the velocity makes corrosion speed faster and faster. So we should properly control the molten salt flow velocity in the safe range.
    There are four main kinds of molten salt pump. They are vertical cantilever pump, vertical pump, vertical submerged pump, axial flow pump. Vertical cantilever pump can be installed in the tank or tank body. It does not need to install bearing on the support and simple disassembly. Vertical pump need to install radial bearings and also can be installed in the tank and the tank body. But if you want to dismantle, it is very difficult. Vertical submerged pump does not have a longer catheter. So it can only install on the outside of the tank. The most difficult question is to remove. Pump axial flow pump through the special design, installed in the upper part of the fixed position, the most simple installation and disassembly. Molten salt pump in molten salt tank within the specific installation position is very important, not only to keep the seal to prevent the heat, but also pay attention to insulation, prevent the pump body temperature is too high, both of which contradict each other. Empirical data on the pump body is fixed to the end of the molten salt distance should be at least 1.5 meters above.
    Molten salt pump before the operation to be pre warm, warm up temperature per hour should not be more than 12~15 degrees Celsius, until the temperature rises above the melting point of molten salt, before the operation can be carried out.
    Domestic manufacturers is also has the production of molten salt pump manufacturing capacity, but its main application in chemical field such as melamine, the alumina production. In application of power stations, domestic manufacturers lack of practical operational experience.