Classification method and maintenance tips for working pressure vessels of liquid nitrogen storage tanks

Firstly, the classification method of working pressure vessels for liquid nitrogen storage tanks. For ultra-low temperature working pressure vessels, when filling liquid nitrogen in liquid nitrogen storage tanks, transpiration needs to be restored to the small phase system after 48 hours. The time required for liquid nitrogen storage tanks to restore the small phase system can be reduced to 12 hours, and transpiration damage can be selected. We have understood the characteristics of liquid nitrogen and the simple structure of liquid nitrogen storage tanks, so that we can fully utilize its functions by applying it. Here is an important summary of the application:

Firstly, there should be dedicated personnel to handle the application, application, and maintenance. The liquid nitrogen storage room should have smooth gas flow. If multiple liquid nitrogen storage tanks are stored in a closed room, the evaporated N2 will stay in the room, resulting in insufficient oxygen and possibly causing chamber breathing disorder. In actual operation, the liquid nitrogen storage tank should be handled with care to prevent collision with other objects. Due to the fact that the liquid nitrogen storage tank becomes a vacuum pump with a height to width ratio through the exhaust pipe, the working pressure of the tank in the table is quite high. Taking DR-10 and DR-30 as examples, the working pressure of the outer tank, although it is made to have a compressive strength that can withstand three times its own weight, needs to be detailed in actual operation to avoid loss or impact.

Secondly, when filling liquid nitrogen once or when the inside of the liquid nitrogen storage tank is in a dry and boring situation, it is necessary to first conduct inspection to see if there are any depressions or other natural environments outside the tank.

. Is there any dirt in the can, and is the base firmly secured. This natural environment can be filled with liquid nitrogen and should be located in a naturally ventilated area, usually outdoors. When in the room, windows and doors must be opened to connect for ventilation and air exchange. One method of filling liquid nitrogen is the pressure introduction method, which involves opening a liquid valve and connecting a flexible plastic hose to a large liquid nitrogen container, and immediately filling the liquid nitrogen storage tank with liquid nitrogen. Another method is to immediately use the Buchner funnel pouring method, which requires specific details to make the Buchner funnel slightly free from the neck tube, so that the vapor evaporated by liquid nitrogen can successfully escape from the gap between the Buchner funnel and the container. Otherwise, the liquid will overflow from the Buchner funnel, which will not only enhance the damage of liquid nitrogen, but also cause confusion due to freezing. The speed of filling liquid nitrogen should be slow. First, introduce a small amount, then pause for a few minutes to allow it to cool down before slowly filling it to the designated volume. There are many classification methods for work pressure vessels, based on the focus points of application, manufacturing, and inspection, including the following categories.

(1) Divided by the level of accepted working pressure: bottom pressure vessel, high-pressure vessel, high-pressure vessel, and high-pressure vessel.

(2) Classified by the substance in which it is stored: non flammable; Flammability or; Toxic.

(3) Divided according to the actual effects throughout the entire processing technology:

① Reaction vessel: a container used to complete physical and chemical reactions of substances.

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② Heat transfer container: a container used to communicate and exchange the heat generation of a substance.

Industrial grade liquid nitrogen changes from N2 to colorless liquid at very low temperatures. At this point, the temperature of the liquid nitrogen is very low. Then, it is filled in a gas cylinder and placed at room temperature. Due to the rise in natural environmental temperature, the liquid nitrogen contained in the cylinder will change, that is, vaporize, and change from liquid nitrogen to gaseous nitrogen. The working pressure of the cylinder will increase. At this time, the temperature inside is still the temperature at which liquid nitrogen and nitrogen coexist, usually -196 ℃. As the temperature of digesting and absorbing external heat continues to rise, the working pressure will continue to rise. The pressure relief valve may have a practical effect to carry out pressure relief. If the pressure is not relieved, only the temperature is raised, and the working pressure of liquid nitrogen in the cylinder will increase.

Generate high-pressure container engineering.

Secondly, maintenance tips for liquid nitrogen storage tanks

1. Before using the LN2 vertical low-temperature storage tank, a small amount of liquid nitrogen should be added to pre cool it. When the temperature inside the tank reaches the liquid nitrogen temperature, fill the tank with liquid nitrogen.

. Be careful when handling liquid nitrogen storage tanks to prevent collision and compression. Do not drag or move them on the ground, and lift them up. When not in use, the liquid nitrogen storage tank should be stored in a dry and well ventilated room to prevent moisture.

2. Check the neck plug and neck plug groove at any time, remove the ice on the neck plug in a timely manner, and do not place plastic cloth or other substances on the neck plug. The use function of the liquid nitrogen storage tank.

. When the consumption rate of liquid nitrogen is too fast or there are water droplets or white frost near the neck of the liquid nitrogen storage tank, it indicates that the insulation function of the tank is malfunctioning and liquid nitrogen cannot be retained. The specimens placed in the liquid nitrogen storage tank should be properly labeled, and the retrieval and placement should be stable, accurate, and fast. Liquid carbon dioxide is a refrigerant that can be used to preserve food and also for artificial rainfall. It is also an industrial raw material that can be used to produce soda ash, urea, and soda water. Liquid carbon dioxide is also used in cooling agents, welding, casting industry, refreshing beverages, fire extinguishing agents, carbonate manufacturing, insecticides, oxidation inhibitors, plant growth industry, sugar industry, glue and animal glue manufacturing, etc.

1、 Operators should conduct regular inspections, observing the pressure inside the kettle, pipeline pressure, whether there is any air leakage in the gasket, whether the drainage valve is tightly closed, whether the reversing valve is tightly closed, and whether the exhaust valve is closed.

2、 When maintaining constant pressure, the main steam valve should be closed in a timely manner to prevent accidents caused by high pressure or steam reflux in the kettle when the main steam pressure is low.

3、 When pouring steam, it is necessary to first check whether the steam pouring valve devices of other kettles, especially those that are pulling piles, are installed to prevent steam from flowing out of the kettle through the steam pouring pipeline and causing injury. When opening the kettle door, pay attention to whether there is water in the kettle. If there is water, slowly drain it before opening the door to avoid water gushing out and injuring people. After the steam supply is completed, the drainage should be carried out according to the operation steps of opening small first and then large.