1. Introduction and use of liquid nitrogen
1.Introduction of liquid nitrogen
Liquid nitrogen, chemical formula N2, molecular weight 28g mol, at 101At 325kPa, the boiling point is -19579, and the freezing point is -210. Liquid nitrogen is a very stable substance that does not easily undergo chemical reactions, but under certain conditions, such as high temperature and high pressure, it can react with other substances.
2.Uses of liquid nitrogen
Liquid nitrogen is chemically inert and can come into direct contact with biological tissues, and can be frozen immediately without destroying biological activity, so it is widely used in many fields, such as:
1) Industrial use: Liquid nitrogen is mainly used in metal cutting, welding, refrigeration and other fields in industry. For example, during metal cutting, liquid nitrogen can quickly freeze the metal, making it easy to cut.
2) Scientific research: Liquid nitrogen has a wide range of applications in scientific research, such as the study of superconducting materials, low-temperature physics, etc.
3) Medical use: liquid nitrogen can be used in the medical field to freeze tumors, diseases, etc. In surgery, liquid nitrogen can be used to help stop bleeding and remove superficial areas of the surface that need to be removed. In addition, liquid nitrogen can be used to preserve living tissues, biological samples, and the storage of sperm and eggs.
4) Food processing: The low temperature of liquid nitrogen can be used for food freezing and preservation, and at the same time, it can also improve the quality and taste of food. It can also be used to make concentrated or dried foods.
2. The material of the liquid nitrogen conveying hose
Liquid nitrogen, a cryogenic liquid with a wide range of applications, is of great importance in industry, scientific research and medical fields. However, the special properties of liquid nitrogen also place extremely high demands on conveying equipment.
There are many ways to transport liquid nitrogen, including liquid nitrogen pump transportation, liquid nitrogen internal pressure transportation, liquid nitrogen container internal pressure transportation, and liquid nitrogen evaporation and condensation transportation. As a key component of liquid nitrogen transportation, the choice of material is very important, and the common materials of liquid nitrogen delivery hose are as follows:
1.Stainless steel:Stainless steel is a highly corrosion-resistant, high-strength metal material that is commonly used in the manufacture of liquid nitrogen transfer hoses. It is able to resist low temperatures and high pressures of liquid nitrogen while maintaining good mechanical properties and chemical stability.
2.Polytetrafluoroethylene (PTFE):PTFE is a polymer compound with excellent heat and oxidation resistance as well as excellent chemical stability and lubricating properties. It is widely used to make liquid nitrogen transfer hoses because it prevents liquid nitrogen from reacting with the surrounding environment and reduces frictional resistance and unnecessary heat loss.
3.High-density polyethylene (HDPE):HDPE is also one of the commonly used liquid nitrogen conveying hose materials, which has good low temperature resistance and is not easy to deteriorate due to the influence of liquid nitrogen. In addition, it has certain pressure resistance and impact resistance, which is suitable for high-pressure liquid nitrogen transmission occasions.
In summary, the three materials of liquid nitrogen transfer hoses, stainless steel, polytetrafluoroethylene (PTFE) and high-density polyethylene (HDPE), have their own advantages and disadvantages, and are suitable for different application scenarios. When choosing a liquid nitrogen delivery hose, the most suitable liquid nitrogen delivery hose should be selected according to the actual needs, taking into account the corrosion resistance, low temperature resistance, strength, friction coefficient and other factors of the material. Liquid nitrogen