Thu, 12 Jul 2018 02:06:05 +0000
What is the main purpose of using a vacuum furnace
The primary purpose of using vacuum furnace for heating, in the process of heating demand and need rapid heating rate, heating material must be selected to ensure that good thermal conductivity, and does not produce deformation at high temperature and large amounts of heat loss, to ensure that in use process performance should be stable over a period of time.
When selecting heating elements, the chemical properties of the products should also be handled according to their own requirements, so as to avoid the material of heating elements affecting the quality of the workpieces. Therefore, the vacuum furnace should reasonably select heating elements.
Graphite heating elements: graphite with high temperature resistance, small thermal expansion, strong thermal shock resistance characteristics, and its mechanical strength under 2500 ℃ temperature rise and improve, around 1700 ℃ best, more than all of the oxide and metal. Graphite material high melting point, low vapor, vacuum furnace atmosphere containing low concentration of carbon, with residual gas of oxygen and water vapor reaction purification effect, greatly simplifying the vacuum system, reduce the cost. In the manufacture process of vacuum furnace, graphite is usually used for heat treatment, including its furnace bed support, heat preservation screen, connecting plate, connecting nut, air vent pipe, etc.
Stainless steel heating elements: small size, large power, fast thermal response, high temperature control accuracy, high comprehensive thermal efficiency, wide application range, strong adaptability, high heating temperature, long life, high reliability. The mechanization degree is high, can bend all sorts of shape according to the customer’s request, portable, disassemble and install convenient. Simple structure, low material consumption, low cost, long service life, high heat transfer rate, and energy saving.
Reasons why the vacuum furnace can’t pump clean air:
In the usual test if there is a liquid, you need a process of liquid evaporation (and don’t need to be heated under high vacuum gasification), can I take a long time to pull a vacuum to gasification off this part of the liquid so as to achieve high vacuum (stability), etc. If long time can not meet the target pressure, will consider system and roots pump, you can directly measure the limits of roots pump vacuum (not connected to other systems), if condition is sealing performance of the system.
The vacuum furnace is suitable for use in radiator heating system.
The heat medium design temperature of radiator hot water heating system is generally determined according to the requirements of thermal comfort, safety and economy of system operation. Water supply temperature does not exceed 95 ℃, can ensure that heat medium under the condition of normal pressure not vaporize, used to use for the return water temperature of 95 ℃ / 70 ℃. But in recent years, according to the heating at home and abroad advanced experience, appropriate to reduce the heat medium temperature, improve comfort, commonly so often use 80/60 ℃. The vacuum hot water boiler in radiator heating system design to meet the requirements of the in and out of the water temperature is 80/60 ℃. Now, by the urban heat supply network or community centralized heating boiler room of a house, even if the design temperature for the 95/70 ℃, when the outdoor temperature reached design, run the water temperature as long as 70/55 ℃ or so commonly, can guarantee the design indoor temperature. Because decided the main factors of fin efficiency is the cooling area of the heat sink and the heat sink inside medium velocity (temperature has little to do with the media), and equal temperature difference of the same cycle water carries the same heat. Different from traditional vacuum hot water boiler boiler (95/70 ℃) on the radiator heating system is mainly room heating time than conventional boiler 4 ~ 5 minutes slow.