Is there any safety risk when circulating fluid in an LNG storage tank when its liquid level is too low, to the point where the drainage pump cannot be started?
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Due to the issue with the gas supply, our factory has been unable to carry out production. The maximum filling level for a 5,000-cubic-meter LNG storage tank is 15 meters, and at present only 1 meter remains. Currently, pumps are used to create circulation in order to maintain the temperature of the tank. As the weather gets hotter, if the liquid level drops any further, it will no longer be possible to operate the pumps. There is a risk of the tank overturning; what should be done if the pumps cannot be used for circulation? We are seeking advice on this matter
Should we check against the relevant LNG standards to see if there are any safety hazards?
With the liquid level so low, it is not recommended to start the pump, as not many trucks’ worth of liquid can be pumped out. Also, are there any issues with the insulation of the storage tank? Is it necessary to use liquid for cooling? And will the production have to be stopped for a long time? If it’s a prolonged shutdown, it is recommended to drain the liquid from the tank.
Theoretically, a situation may arise where the top of the tank is hot while the bottom is cold. Lift it up and have experienced colleagues take a look – can it roll?
It won’t roll over; there will be a temperature difference between the top and bottom of the tank, but it doesn’t have much impact. Pre-cool it again before starting it up next time.
The tank vent is opened to prevent the tank pressure from rising. As the storage tank absorbs heat due to environmental influences, the liquid inside it will evaporate; it’s unclear how long this can be sustained.
If there are no issues with the insulation of the storage tank, it can simply be left as it is; the evaporated gas from LNG will be sufficient to maintain the temperature of the tank. At this point, it is necessary to regularly check the pressure and temperature changes in the tank. If no production is taking place, then it’s important to determine how often production should resume. Do you have a BOG recovery system in place? If the interval between production sessions is too long, the liquid content in the tank should be removed. Stop the pump; there’s no point in running it – would that increase the amount of vapor produced? Laughing {:3_67:}