Working principle of vacuum furnace

The vacuum boiler is a vacuum environment with negative pressure formed in the closed furnace body, which is filled with heat medium water. The heat medium water is heated by combustion or other means, evaporated and condensed by the heat medium water to the heat exchanger, and then the water to be heated is heated by the heat exchanger.
Heat conversion diagram of vacuum boiler:
Oil, natural gas, gas, electricity -- > combustion (electricity conversion heat) - > heat medium water -- > steam condensation heat transfer after boiling -- > heat exchanger -- > heat conduction -- > water

Working principle of vacuum boiler: use the low boiling point of water under the low pressure condition to quickly heat the heat medium water filled in the sealed furnace body, so that the heat medium water boils and evaporates the high-temperature water vapor, and the water vapor condenses on the heat exchange tube to heat the cold water in the heat exchange tube, so as to supply hot water.
Standard sea level atmospheric pressure: 1.013 × 105Pa = 101.3kPa, at this time, the boiling point of water is 100 ℃; the higher the altitude, the lower the atmospheric pressure, the lower the boiling point is:
Qinghai Tibet Plateau: the average altitude is 4000m, the atmospheric pressure is 62kpa, and the boiling point of water is 87 ℃;
Mount Everest: the altitude is 8848m, the atmospheric pressure is 33kpa, and the boiling point is 71 ℃;
The vacuum boiler forms a low-pressure environment with almost no air by vacuuming, and then uses water to boil at low pressure (lower than atmospheric pressure) to generate steam, and uses steam water condensation heat exchange to output heat.
Corresponding table of boiling point and vacuum degree of water:
Vacuum degree (kPa) 0-31-54-70-81-89-94-97-99-101
Boiling point of water (℃) 100 90 80 70 60 50 40 30 200
The normal working temperature of vacuum boiler is lower than 90 ℃, and the vacuum degree is lower than - 30KPa.
The heat medium water in the vacuum boiler is a high-purity water specially treated by deoxidation and descaling. It is filled once before leaving the factory. When it is used, it is closed and circulates inside the unit (vaporization → condensation → vaporization), without increase or decrease, and does not need to be supplemented or replaced within the service life of the unit.
Therefore, the inside of the vacuum boiler body will never scale or corrode, and its normal service life can be more than 20 years, which is far beyond the service life of the ordinary hot water boiler for about 10 years.