The main purpose of using vacuum furnace is to heat

The main purpose of using vacuum furnace is to heat

The main purpose of using the vacuum furnace is to heat. During the heating process, it is required to have a fast heating rate. The selected heating materials must ensure good thermal conductivity, and can not produce deformation and a large amount of heat loss at high temperatures. It is necessary to ensure that the performance is stable during use for a period of time.

When selecting the heating element, the chemical properties of the product to be treated should also be considered, so as to prevent the material of the heating element from affecting the quality of the workpiece. Therefore, the vacuum furnace should reasonably select the heating elements.

The heating elements commonly used in high vacuum sintering furnace are graphite and stainless steel.

Graphite heating element: graphite has the characteristics of high temperature resistance, small thermal expansion, strong thermal shock resistance, etc. Its mechanical strength increases with the increase of crushing temperature below 2500 ℃, and 1700 ℃ is the best, surpassing all oxides and metals. Graphite material has high melting point and low steam pressure. The atmosphere of vacuum furnace contains low concentration carbon, which will react with oxygen and water vapor in residual gas to produce purification effect, greatly simplifying the vacuum system and reducing the cost. In the manufacturing process of vacuum furnace, the heating element commonly used for heat treatment is graphite, including its hearth support, insulation screen, connecting plate, connecting nut, vent pipe, etc.

Stainless steel heating element: small size, large power, fast thermal response, high temperature control accuracy, high comprehensive thermal efficiency, wide application range, strong adaptability, high heating temperature, long service life, and high reliability. It is highly mechanized and can be bent into various shapes according to customer requirements. It is light and convenient for disassembly and assembly. The utility model has the advantages of simple structure, less material consumption, low cost, long service life, high heat conversion rate, and energy conservation.

The reason why the vacuum furnace cannot pump clean air:

In normal tests, if there is liquid, it needs a liquid evaporation process (it can be vaporized without heating under high vacuum). This part of liquid can be vaporized by pulling vacuum for a long time to achieve high vacuum (equal stability). If the target pressure cannot be reached for a long time, the system and roots pump should be considered. You can directly measure the limit vacuum of roots pump (not connected to other systems). If it is intact, it is the sealing performance of the system.

Vacuum furnace is suitable for radiator heating system.

The design temperature of heat medium of radiator hot water heating system is generally determined according to the requirements of thermal comfort, the safety and economy of system operation, etc. The water supply temperature shall not exceed 95 ℃, which can ensure that the heat medium will not vaporize under normal pressure. Previously, the supply and return water temperature was 95 ℃/70 ℃. However, in recent years, according to the advanced experience of heat supply at home and abroad, it is beneficial to improve the comfort by appropriately reducing the temperature of heat medium, so 80/60 ℃ is usually used. The vacuum hot water boiler shall meet the requirements of 80/60 ℃ inlet and outlet water temperature when designing the radiator heating system. Now, even if the design water temperature is 95/70 ℃ for residential buildings heated by urban heat supply network or district centralized boiler room, when the design outdoor temperature is reached, the operating water temperature is generally about 70/55 ℃, which can ensure the design indoor temperature. Because the main factors determining the efficiency of the heat sink are the heat dissipation area of the heat sink and the flow rate of the medium in the heat sink (which has little relationship with the temperature of the medium), and the heat carried by the same circulating water volume with the same temperature difference. The vacuum hot water boiler is different from the traditional boiler (95/70 ℃). In the radiator heating system, the heating time of the room is 4-5 minutes slower than that of the traditional boiler.