Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
  • F24H1/22—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating
  • F24H1/24—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers
  • F24H1/26—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body
  • F24H1/28—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body including one or more furnace or fire tubes
  • F24H1/285—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water mantle surrounding the combustion chamber or chambers the water mantle forming an integral body including one or more furnace or fire tubes with the fire tubes arranged alongside the combustion chamber
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H9/00—Details
  • F24H9/0005—Details for water heaters
  • F24H9/001—Guiding means
  • F24H9/0026—Guiding means in combustion gas channels
  • F24H9/0031—Guiding means in combustion gas channels with means for changing or adapting the path of the flue gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
  • F28D21/0017—Flooded core heat exchangers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
  • F28D21/0001—Recuperative heat exchangers
  • F28D21/0003—Recuperative heat exchangers the heat being recuperated from exhaust gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/0066—Multi-circuit heat-exchangers, e.g. integrating different heat exchange sections in the same unit or heat-exchangers for more than two fluids
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
  • F28D7/163—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation with conduit assemblies having a particular shape, e.g. square or annular; with assemblies of conduits having different geometrical features; with multiple groups of conduits connected in series or parallel and arranged inside common casing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/26—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators

Definitions

• the present invention refers to an apparatus for recovering thermal energy from the exhaust fumes and gases of heat engines and from the cooling and ventilation air and/or any of the components or auxiliary circuits of the same plants, or of other plants.
• the invention refers to heat generators adapted to serve as heat recovery apparatuses.
• said heat generators are fire-tube apparatuses.
• Cogeneration is essentially based on using the heat generated by the electricity production phase of thermoelectric generators; such
• micro cogeneration enables widespread, small- scale distributed production of electrical energy for households, the tertiary sector and small-sized industries, whose power requirements are relatively modest.
• the thermal energy produced by the functioning of a prime mover (be it an internal combustion engine or a micro gas turbine) is partly dissipated in the external environment by radiation; while this fraction can effectively be reduced, most of the thermal energy is transferred to the combustion gases (whose temperature in fact ranges from 350 to 600 °C) discharged to the flue and to the cooling air of various engine components and auxiliary circuits.
• Heat is not usually recovered from cooling air, essentially due to its low enthalpy and convective heat transfer coefficient, which would require exchangers endowed with large exchange surfaces, adversely affecting the cost/benefit ratio of the cogenerator. Only rarely is cooling air harnessed to heat water, generally in alternative internal combustion engines.
• Such devices are usually fitted downstream of the prime mover; they may be exchangers (also known as recuperators), which use the heat of the combustion fumes, for example to preheat the combustion air, or recovery furnaces, where the fumes are further burned or merely cooled via heat exchangers, preferably dedicated to production of steam, hot water or superheated water.
• exchangers also known as recuperators
• apparatuses for the recovery of the enthalpy of prime mover combustion gases and fumes have a major drawback: their close integration with the engine itself. As a consequence, malfunction of the prime mover or the heat recovery apparatus can compromise the overall efficiency of the cogeneration system. In addition, separate maintenance of the engine and the heat recovery apparatus is difficult, since it generally requires also the shutdown of the component functioning correctly.
• a first object of the disclosed invention is to devise a simple and economical heat recovery method in relation to the amount of thermal and electrical power involved.
• a second object of the invention is to devise a heat recovery method characterized by low pollutant emissions and environmental impact.
• a further object of the disclosed invention is to devise a heat recovery method characterized by high flexibility in terms of the number and type of plants from which heat can be recovered.
• Another object of the invention is to devise high flexibility means to integrate a prime mover and a fire-tube boiler in terms of the amount of electrical power to be integrated.
• FIG. 1 is a schematic perspective view of a heat generator according to the prior art
• FIG. 2 is a block diagram of a heat recovery apparatus according to the disclosed invention.
• figure 2 of the attached diagrams 1 indicates overall the heat recovery apparatus, the subject of the invention, which includes one or multiple generic heat sources 2 and a heat generator 3.
• said generic heat sources 2 can be electrical and/or mechanical power generators, such as internal combustion engines, micro gas turbines, steam turbines, fuel cells; simpler heat sources such as low-efficiency heat generators, whose fumes can still be used to extract thermal energy; and even simpler devices such as heat exchanger batteries of cooling systems of plants such as plastic stamping or extrusion machines.
• said heat sources 2 emit heat substantially as hot gases, i.e. combustion gases Fl and/or cooling and ventilation air F2 heated by the cooling of various types of equipment.
• Said heat sources 2 can be for instance: - internal combustion engines and micro gas turbines, where heat is generated both as combustion gases Fl and as auxiliary circuit cooling and ventilation air F2,
• Hot gases Fl and F2 generated by said heat sources 2 are often insufficient in amount and/or temperature for heat recovery to be feasible and/or economical through individual recovery apparatuses.
• FIGs 1 and 2 schematically show the combustion chamber (or furnace) 31, the heat exchanger 32, and the flue 36 of the heat generator 3.
• the enthalpy of the hot gases Fl and F2 issuing from the heat source 2 is recovered by said generator 3. More precisely, the combustion gases Fl, whose temperature is sufficiently high, are sent to the exchanger 32 to transfer heat, whereas the cooling air F2 is used in the same generator 3 as combustion air for the furnace 31.
• the features of the fire-tube boiler 3 shown in the schematic view of figure 1 and in figures 4a through 5c are a furnace 31, usually cylindrical, where combustion occurs, and a number of pipes 33, constituting overall the exchanger 32, carrying the exhaust gases. Said pipes 33 are arranged into bundles (or fume circuits) in which the gases course, passing through the boiler 3 once or multiple tunes.
• the furnace 31 and pipes 33 are surrounded by water A (in liquid and steam state); the water is contained in a cylindrical vessel 38 fitted at either end with pipe plates 3801 for the insertion of the furnace 31 and pipes 33.
• a hatch 37 for inspection and maintenance, commonly found on the front of the boiler 3, is schematically drawn in figures 4a through 5c.
• the boiler 3 Upstream of the furnace 31 the boiler 3 also includes at least a burner and the respective fan (or blower), to supply combustion air (not shown in the figures). All known components of the boiler 3 have now been described.
• a conveyor 4 carries said combustion gases Fl to at least one part of the exchanger 32, to recover their thermal energy.
• the inspection hatch 37 is modified compared with the prior art, to accommodate the conveyor 4 passing through it.
• Said conveyor 4 is characterized by an outer part 41 connected directly, or indirectly through ducts, to said one or multiple heat sources 2, to collect their combustion gases Fl, and by an inner part 42, which is designed to couple to one or more pipes 33 of the heat exchanger 32 of the fire-tube boiler 3, in particular one or more pipes 33 of at least the third fume circuit 3303, and whose opening 4201 presses against the front pipe plate 3801.
• the internal part 42 is designed to rotate and translate axially with respect to the outer part 41, where it is partially inserted, to allow coupling of the conveyor 4 to one or multiple pipes 33, as required by the flow rate and temperature of the combustion gases Fl, or to prevent the conveyor 4 from interfering with said pipes 33 if no combustion gases Fl from which energy can be recovered are present.
• said conveyor 4 is preferably a telescopic conduit consisting of an outer part 41 coupled hermetically to the inspection hatch 37, and of an inner part 42 capable of rotation and axial translation with respect to the outer part 41, where it is partially inserted, via a telescopic coupling 5 (schematically represented in the enclosed figures).
• said rotation is enabled by the circular conduit tracts 4101 and 4205 of said joint 5, to which the outer 41 and inner part 42 of the conduit 4 are coupled (see in particular figure 5 c).
• the opening 4201 of the mobile internal part 42 is preferably elliptical and/or circular. Axial translation of the inner part 42 with respect to the fixed external part 41 enables the opening 4201 to approach the pipe plate 3801 within the inversion chamber 35, to intercept said one or more pipes 33, whereas its rotation selects the pipes 33 of said plate 3801 that will carry the combustion gases Fl of the heat source 2, and consequently the number of passes of the combustion gases Fl through the heat generator 3.
• said pipes 33 intercepted by said opening 4201, therefore define the part 3201 of the heat exchanger 32 of the boiler 3 dedicated to cooling the sole combustion gases Fl of said one or multiple heat sources 2.
• the conduit 4 is capable of connecting to a suitable number of pipes 33 belonging solely to the third fume circuit 3303, whereas, as clearly shown in figures 4b and/or 4c, the inner part 42 of the conduit 4, as a result of its rotation, can connect simultaneously to multiple pipes 33 of the third circuit 3303 and to at least one pipe 33 of the second circuit 3302.
• One or more magnets can also be fitted in close proximity to the opening 4201 of the conduit 4, for an enhanced coupling of the conduit 4 and the pipe plate 3801, and thus a perfect seal.
• any means known in the prior art can be used to press the opening 4201 against the pipe plate 3801.
• an additional fan (not shown) can be applied to the flue 36, to enhance circulation of the combustion gases Fl through the fire-tube boiler 3, by forcing them through said pipes 33 of its exchanger 32.
• the configuration (particularly the rotation angle of the mobile internal part 42 of the conduit 4) can be selected manually.
• an electronic control unit selecting the most appropriate configuration of the conduit 4 in response to the changes in said physical parameters, which are detected through special sensors.
• the larger the portion 3201 of the heat exchanger 32 dedicated to the combustion gases Fl the smaller the thermal power that can be supplied to the furnace 31, but modulation of such power is automatically provided by control means with which the heat generator 3 is usually endowed.
• the power supplied to the furnace is modulated by the user's demand for heat energy, which is met with lower furnace 31 loads if combustion gases Fl are present.
• cooling and/or ventilation air F2 warmer than the ambient temperature (from 60 °C to 90 °C), is sent by known means directly to the furnace 31 of the boiler 3 and used as combustion air.
• the heat source 2 therefore serves as a preheater unit of the combustion air for the internal combustion of the boiler 3. Recovery of such additional heat energy in the boiler 3, coupled to the heat recovered from the combustion gases Fl, therefore increases the overall efficiency of the heat recovery apparatus 1, which is subject of the invention.
• the heat source 2 is preferably a prime mover for electrical energy production. Even more preferably such prime mover 2 is, as noted above, an internal combustion engine or a micro gas turbine, two well-established and reliable technologies that require no further description.
• the heat recovery apparatus 1 according to this preferred embodiment is therefore a cogeneration plant for combined electrical and thermal power production, to which all the above considerations apply.
• the prime mover 2 can lack the traditional integrated recuperator, since it is connected (through said conveyor 4) to the boiler 3, where the heat that would otherwise be dissipated as combustion gases Fl and cooling and/or ventilation air F2 is efficiently recovered.
• the prime mover 2 (or in general the heat source 2) can be joined, through the telescopic conduit 4, to the back of the fire- tube boiler 3, rather than at the level of the inspection hatch (suitably modified to house said conduit 4) as described above.
• the mobile inner part 42 is capable only of axial translation with respect to the fixed part 41, not also of rotation. Such configuration is especially practical, as noted above, when the physical parameters of the combustion gases Fl are substantially constant over time and the part 3201 of the heat exchanger 32 dedicated to said combustion gases Fl can be selected manually.
• the conveyor 4 includes only the external part 41 (henceforth, for the sake of simplicity, the conduit 41), hermetically coupled to the inspection hatch 37 but capable of axial translation to connect to the pipes 33 of the exchanger 32 of the boiler 3 dedicated to said combustion gases Fl.
• the possibility to dedicate part of the heat exchanger 32 of the boiler 3 to cooling the sole combustion gases Fl of said prime mover 2 and to recover cooling and/or ventilation air F2 significantly enhances the overall efficiency of the cogeneration apparatus 1 and allows nearly total recovery of its thermal loss. It is also clear that integration of an existing boiler 3 with an engine 2 suitable for electricity generation can be achieved with a modest investment by any user, who can select the most appropriate size for their level of consumption. Said cogeneration apparatuses 1 are therefore capable of meeting also a user demand characterized by high thermal and low electrical power production. This is easily achieved by replacing the standard hatch 37 of the fire-tube boiler 3 with an additional hatch capable of housing and supporting the conveyor 4.

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Citations (7)

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• 2009
  • 2009-05-20 IT ITAN2009A000023A patent/IT1394354B1/it active
• 2010
  • 2010-05-18 CN CN2010800223457A patent/CN102439375A/zh active Pending
  • 2010-05-18 RU RU2011152029/06A patent/RU2491481C1/ru not_active IP Right Cessation
  • 2010-05-18 EP EP10726205A patent/EP2443398A1/en not_active Withdrawn
  • 2010-05-18 US US13/321,151 patent/US20120067549A1/en not_active Abandoned
  • 2010-05-18 WO PCT/IB2010/001174 patent/WO2010133951A1/en active Application Filing

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