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The construction method of LNG Vehicle Cylinder

Sep. 18, 2019

  LNG Vehicle Cylinder is a storage tank specially used for storing LNG. The LNG storage tank is a mezzanine storage tank. Since the temperature of liquid natural gas is lower than -162 degrees Celsius, LNG storage tank is also a low-temperature storage tank. In order to meet the requirements of liquefied natural gas, LNG storage tanks should be made into jackets to ensure the temperature inside the tanks in order to reduce the introduction of external heat into the tanks. The designed inner and outer tanks are separated and independent. Many people may have heard that LNG storage tanks are quenching and liquid shocking, but they don't know what the situation is. The low-temperature storage tank manufacturers will give a brief introduction.

  Due to the intermittent nature of the LNG vehicle refueling, the equipment in the refueling station repeatedly starts and stops, and the opening or closing of the valve or the pump causes the flow velocity of the liquid in the pipeline to suddenly change, sometimes it may be a drastic change and the momentum of the liquid also changes. The pressure inside the pipe rises or falls rapidly, accompanied by the sound of liquid hammering, a phenomenon called the liquid hammer (or water hammer). The liquid impact will cause a drastic change in the pressure inside the pipeline, and the pressure will suddenly rise. In severe cases, the pipeline may burst, and the rapid pressure drop will cause the pipeline to be under pressure, which will cause the pipeline to be unstable and cause the pipeline to vibrate.

LNG Vehicle Cylinder

LNG Vehicle Cylinder

  Quenching refers to the rapid cooling of pipes or equipment in a short period of time. Due to the intermittent operation of the LNG refueling station, during the process of abruptly starting the refueling or unloading after the system is running, especially the running start may cause quenching. The quenching phenomenon will form a temperature gradient at the top and bottom of the pipeline, causing the pipeline between the two supports to flex. Due to the large flexural stress, the pipeline is at risk of breaking.

  LNG Vehicle Cylinder Manufacturer recommends that in order to prevent the occurrence of quenching and water hammer, the cold shrinkage of the pipeline caused by the low-temperature characteristics of the medium in the pipeline should be taken into consideration in the design, and a reasonable pipeline compensation method should be set; the gas station must be operated before operation. Pre-cooling of equipment and pipelines; the speed of opening and closing of pumps and valves must not be too fast during operation. It is recommended to use valves with longer strokes, such as low-temperature shut-off valves, to prevent sudden rise and fall of pressure.

  Introduce the construction method of LNG cryogenic storage tanks. LNG cryogenic storage tanks can be generally divided into flip-chip construction and formal installation. They are all used under the LNG Semi-Trailer to see the advantages and disadvantages of them.

  Flip-up construction advantages:

  (1) Both internal and external tanks are hydraulically jacked up. There is no need to set up scaffolding. The construction of inner and outer tank walls and tank tops requires cranes (outer tank top installation), and the construction cost is greatly reduced.

  (2) Except for tank top installation, all installation and inspection work is carried out on the ground, which has high work efficiency and is conducive to quality control and safety management.

  Advantages of formal construction:

  (1) The inner and outer tank walls are alternately constructed, and the working surface is relatively wide. Under the premise of ensuring resources, it is conducive to shortening the construction period.

  (2) Since there are scaffolding inside and outside the tank and the interlayer, the non-destructive testing will not affect the installation of the next wall.

  (3) The tank wall construction is carried out in the open air, and the construction site maintains good ventilation.