The LNG tank is equipped with a temperature measuring device for measuring the inner tank (LNG temperature measurement), the inner surface temperature of the steel tank wall and the tank bottom temperature. There are two temperature monitors for measuring the temperature of the product. These two temperature monitors are installed in a static well which runs through the top of the tank and the bottom of the tank.

From the measurement of LNG temperature and density in the tank cryogenic storage tank top, tank to monitor the possible danger of flooding. Flooding leads to thermal layer shifted to the surface of the liquid, and accompanied by a large amount of LNG vapor. This will result in an overvoltage hazard that is not allowed.

In order to prevent the occurrence of flooding, liquid pump should bypass operation mode based on maximum flow operation, to increase the natural convection, the mixed LNG.

The storage tank is equipped with 16 temperature sensors, and the 16 temperature sensors are installed in a static well, and the height positions are different. The temperature is displayed on DCS. The temperature measured by the adjacent sensors is compared with each other on the DCS to identify the formation of any temperature layer (stratification, i.e., a relatively hot layer below the cooler layer). In these circumstances, will alert, because at this time there is a potential risk of flooding.

8 temperature sensors are attached to the inner wall of the tank, and the height positions are different. 12 temperature sensors are evenly distributed on different circles of the inner tank bottom. In addition, 4 sensors are distributed at the bottom of the annular space and are evenly distributed.

6.3.3 density display and control system

A density measuring device is installed to measure the LNG density at different depths. Normally, the tank is filled through the bottom pipeline. Only when the LNG density varies greatly, can the top filling be selected.