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    Principle of ZWNS vacuum hot water boiler

The boiling point of water at one atmospheric pressure (1bar) is 100˚C. When the pressure is lower than 1bar, the water boiling point is less than 100˚C. For example, when  pressure comes to  0.7bar, then boiling point will be 90˚C. 0.3bar is related to 70˚C boiling point. The pressure is 0.1bar and the boiling point is 40˚C.


The closed chamber inside the vacuum hot water boiler forms a vacuum chamber after being pumped through the vacuum. The combustion causes the heat medium water to boil and vaporize in the vacuum chamber to produce negative pressure water steam. The steam condenses outside the heat exchanger tube, and the cold water in the tube atmospheric pressure hot water boiler is heated and heated to the user. The normal working pressure of boiler is less than 0.7bar. Heat medium water is a special treatment of high purity water such as descaling and deoxidation, which is filled by the factory before leaving the factory. When used, it is closed in the boiler (vaporization - condensation - vaporization), does not increase, does not reduce, and does not need to be supplemented or replaced within the service life of the boiler vacuum boiler characteristics.


At present, the company's vacuum hot water boilers are divided into ZWNS-Y type fuel oil, ZWNS-Q type gas and ZWNS-D type electric heating vacuum hot water boilers.

              FIG.1     Diagram of ZWNS vacuum hot water boiler

    1, five security protection

    Shangneng vacuum water heater adopts pressure and temperature dual control unit operation, which greatly improves safety performance compared with conventional vacuum water heater (only temperature control). In addition, the vacuum water heater has five safety protection devices to ensure the safe operation of the unit:

    1.1 Overtemperature alarm:

    When the thermal medium temperature exceeds the set alarm temperature (set value 98℃), the burner automatically stops and alarms.

    1.2 Overpressure alarm:

    When the internal pressure of the unit reaches the set pressure (set value 5KPa), the burner automatically stops and gives an alarm.

    1.3 Heat medium water level abnormal protection device:

    When the heat medium water of the unit is lower than the set water level, it will automatically stop and alarm.

    1.4 Gas leak alarm:

    When the unit is running, the unit is equipped with the RIELLO gas leakage detection device to monitor the gas content in the air at any time, when the gas leakage reaches a certain value, the gas inlet solenoid valve automatically closes and alarms.

    1.5 Mechanical explosion-proof device:

    The body of the unit is equipped with a safety explosion-proof device, the explosion-proof valve diaphragm detonation pressure is 0.01MPa, in case the unit pressure exceeds the detonation pressure, the explosion-proof film will automatically break and relieve pressure to the unit.

    2, safe and reliable

    The inside of the unit is in a vacuum oxygen-free state, and the boiler body will not be damaged by corrosion; There is no scale inside the unit, and it can run efficiently for a long time. In order to ensure the reliable operation of the unit for a long time, in addition to the static parts (steel plate, steel pipe, etc.) using domestic high-quality materials, all the rest of the operating parts are imported products, reliable performance, very low failure rate.

    3. Environmental protection and emission reduction

    The Italian RIELLO gas-type combustion machine supporting the vacuum water heater of Shangneng has the characteristics of complete mixing, high combustion efficiency and low NOX emission. The furnace of the unit adopts the wet-back three-pass structure, the combustion is complete, and the combustion efficiency reaches more than 99.99%. Thus, it can fundamentally ensure that the unit's operation meets the most stringent environmental requirements.

    The flue gas emission of the vacuum water heater is in line with GB13271-2001 "National Air Pollution Emission Standard for Class I Regions".

    4, high efficiency and energy saving

    4.1 Unit design: the design heat transfer temperature difference between heat medium water and heat exchange tube is 10℃, which effectively reduces the operating temperature of heat medium water and saves energy consumption of the whole machine;

    4.2 Unit structure: The furnace of the vacuum water heater adopts the wet-back three-return combustion structure, the combustion is complete, the heat transfer area is increased, the thermal efficiency is improved, and the CO content of the exhaust gas is almost 0 (the national standard is 1000PPM), and the combustion efficiency can reach 99.99% or more; The smoke pipe adopts the patented technology of high efficiency heat exchange smoke pipe with internal and external fin and internal thread, which greatly reduces the exhaust temperature and improves the thermal efficiency; The whole machine adopts the front and rear wet back structure, the surface temperature is low, and the energy saving is 2% compared with the ordinary dry back boiler; The whole machine adopts high temperature rubber and plastic insulation, good insulation performance, less heat loss, thermal efficiency up to 94%.

    4.3 Control system: The control system adopts dual control of pressure and temperature, the control sensitivity is increased by 50%, the number of start-up and shutdown times of low-load combustion machine is reduced by 35%, and the pre-purging energy consumption is reduced by 35%; Hot water outlet temperature and heat medium temperature interlocking control burner (used in single loop), compared with the burner only heat medium water temperature control, can save more than 5% of energy consumption; Achieve the system comprehensive energy saving of more than 2%.

1, the use of pressure, temperature dual control unit operation, there are five safety protection devices, safe operation process;

2, the inside of the unit is in a vacuum oxygen-free state, the boiler body will not be damaged by corrosion and the internal scale will never be formed, which can run efficiently for a long time and is very reliable;

3, the combustion efficiency reached more than 99.99%, the matching Italy RIELLO gas type combustion machine has the characteristics of complete mixing, high combustion efficiency, low NOX emission, and actively respond to the national call for energy conservation and environmental protection;

4, the whole machine low energy consumption, high thermal efficiency, the use of independent patents, reliable.

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