Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
  • F24D1/00—Steam central heating systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
  • F24D19/00—Details
  • F24D19/08—Arrangements for drainage, venting or aerating
  • F24D19/081—Arrangements for drainage, venting or aerating for steam heating systems

Definitions

• the present invention relates to an automatic venting device for evacuated-tube steam heating systems.
• Evacuated-tube steam heating systems are already known in the field of thermal engineering.
• the system comprises at least one tube bundle or grid connected in a closed circuit as follows: at one end, to the upper part of a heated vessel which contains a substance having convective properties and is associated with heating means suitable to produce the evaporation of said substance; at the other end, to an unheated vessel (condensate collector).
• the lower part of said heated vessel is directly connected to the tube bundle or grid.
• the tube bundle or grid is arranged so that it can exchange heat with an enclosed space or with other liquid, solid or gaseous materials, either directly or indirectly.
• the tubes can be struck by the air stream produced by one or more fans and the air can be fed directly and/or indirectly into the space to be heated.
• the assembly constituted by the vessels, the grid or bundle of tubes and the connections constitute a sealed vacuum unit and contain a specific amount of a substance, such as water, which is confined to the lower parts of the assembly.
• the liquid contained therein evaporates and the steam tends to occupy all the available volume, thus propagating itself to the tube bundle or in the tube grid, which are empty.
• This condensation creates a new vacuum (or alters the pressure conditions in that region, so that fresh steam takes the place of the condensed steam).
• the condensate tends to flow towards the lower part of the circuit and from there, again due to the slope or to mechanical action, it collects in the lower part of the heated vessel.
• Air which is a good heat insulator, by being confined to these regions does not heat and therefore compromises the operation of the system, forcing a maintenance action which consists in restoring the original degree of vacuum.
• the aim of the present invention is to provide a device which allows automatic venting of any air present inside evacuated-tube steam heating systems.
• a consequent primary object is to provide a venting device which eliminates the need to perform perfect welds or in any case porosity-free welds between the connected parts, allowing to use other coupling systems instead of welds, consequently saving labor and time.
• Another important object is to eliminate maintenance for restoring optimum vacuum conditions.
• an automatic venting device for heating systems comprising one or more heat exchange elements which are individually or globally connected to a heated vessel which contains a substance having convective properties and is associated with heating means which are suitable to cause its evaporation, the condensate of the steam produced by said evaporation collecting directly, by natural or mechanical means, in said heated vessel; characterized in that it comprises a closed container which is connected to one or more regions of said heat exchange elements and is provided with sensors which are suitable to detect the presence of air and with an automatic vent valve, said sensors and said valve being connected to a control and management unit which receives signals from said sensors and opens and closes said valve.
• a metallic box-like structure is internally provided with two regions, respectively a primary one 10a and a secondary one 10b.
• a heated vessel 11 is provided and in the secondary region 10b a condensate return system is provided, constituted in this case by an unheated vessel 12 and by a tube 14.
• a bundle of finned tubes or a grid of tubes or a plate 13 is arranged in the upper part of the structure 10 and is connected to the upper part of the vessels 11 and 12.
• a burner 15 is provided which is coupled to conventional control and safety devices 16 which are required for its operation.
• a coupling 17 for a burnt gas exhaust pipe In the upper part, relative to the burner 15, there is provided a coupling 17 for a burnt gas exhaust pipe.
• the tube bundle or grid or plate 13 is interposed between an outlet grille 18 and a ventilation system which comprises a fan 19, provided with a respective motor 20 and an air intake 21 with a filter 22.
• the assembly constituted by the heated vessel 11, the bundle or grid or plate 13, the unheated vessel 12 and the condensate return tube 14 is a unit which, both when in use and when inactive, is in perfect thermodynamic equilibrium between the steam and its condensate.
• a venting device 23 is connected in an air confinement region which can be higher or lower, according to the circuit of the system, with respect to the tube bundle 13 or grid or plate (by way of example, it is shown in the highest point in Figure 1).
• the device comprises a closed container 24 which is provided with sensors for detecting the presence of air, constituted by a lower thermostat 25 and by a pressure switch 26 and, at the top, with an automatic electric venting valve 27 which is connected to the outside.
• the thermostat 25, the pressure switch 26 and the electric valve 27 are connected to an electronic control and management unit 28 which is connected to an electric power supply 29.
• a water level probe 30 is also present and its terminal is located inside the container 24 and is shown in the upper part only by way of example.
• the water level probe 30 also is connected to the electronic control unit 28.
• the container 24 is constituted by a steel tank whose volume is suitable for the size of the system whereto it is connected, and the control and management unit 28 can be mounted directly on it or be remote.
• the initial condition is the one in which the system is cold and not in vacuum, i.e., in which the internal parts are at ambient pressure.
• the contact of the thermostat 25 in series with the contact of the pressure switch 26 is in the closed state and the control unit 28 opens the electric valve 27 and thus vents the air contained in the system.
• the expelled air is replaced with the steam produced by the heating of the heated vessel 11 in which a specific amount of water is contained.
• the steam by making contact with the probe 30 of the thermostat 25, heats it and, when the set temperature (70 ⁇ 80 ⁇ 90 ⁇ 100°C) is reached, opens the contact, interrupting the supply of power to the electric valve 27, which closes the vent.
• the water level probe 30 interrupts the power supply of the electric valve 27, closing the vent, and restores the power supply when the water has flowed out.
• the electric valve 27 is never opened if the internal pressure does not exceed the setting of the pressure switch 26 (0.1 - 0.2 bar), so as to avoid the inflow of air if the burner 15 stops momentarily.
• a split embodiment of the system there is, for example, a heated vessel 111 (evaporator), an exchanger 113 and outgoing and return pipes 112 and 114.
• a venting device 23 identical to the one described earlier is installed.
• the exchanger in practice differs from the preceding one in that it is contained in a casing and is struck directly by the liquid or gaseous material to be heated.
• a venting device 23 is provided which is identical to the preceding one.
• a third embodiment of the system comprises units which are each constituted by a bundle 313 of tubes which are snugly connected to a metal plate 331 constituted by a sheet of metal, in which the ends are connected, on one side, to a heated vessel 311 by means of a manifold 332 and, on the other side, to the heated vessel 311 by means of a second manifold 333.
• a burner 315 or another system suitable for heating, is associated with the heated vessel 311.
• the plates 331 are also covered, in an upward region, with an insulation which is suitable to limit heat loss.
• the plates can be individual or can be mutually connected so as to constitute strips of considerable length and lie on a single side of the heated vessel 311 or on either side thereof.
• a venting device 23 identical to the preceding ones, is connected in one part of the system.
• evacuated-tube steam heating systems with automatic air venting devices
• said systems have in fact been equipped with devices which are suitable to produce, inside them, the vacuum required for their operation, and all the drawbacks currently observed due to air infiltrations, occurring mainly in less than perfect welds between the various couplings, have been eliminated.
• the venting device can of course also be used as a repressurizer, restoring atmospheric pressure in the system when it is not used.
• the materials employed may be any according to requirements.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Steam Or Hot-Water Central Heating Systems (AREA)
• Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)

Applications Claiming Priority (2)

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• 1997
  • 1997-06-26 IT IT97PD000140A patent/IT1293721B1/it active IP Right Grant
• 1998
  • 1998-06-18 EP EP98111204A patent/EP0887595A3/de not_active Withdrawn

Patent Citations (1)

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