WO2006067820A1

WO2006067820A1 - Boiler condensation module

Info

Publication number: WO2006067820A1
Application number: PCT/IT2005/000737
Authority: WO
Inventors: Stefano Bandini
Original assignee: Stefano Bandini
Priority date: 2004-12-20
Filing date: 2005-12-15
Publication date: 2006-06-29
Also published as: EP1828690A1; EA200701095A1; ITDP20040005A1; JP2008524552A; CN101080598A; CA2591258A1; KR20070090935A; EA011442B1; NO20073373L; US20080110601A1

Abstract

The invention concerns a boiler condensation module, characterised in that it comprises a water/fume heat exchanger (E) and a closed circuit compression thermodynamic frigorific apparatus, said module (2) being communicated with a boiler (1) intercepting the flow of the fumes and the flow of the water, in order to subtract sensitive heat and vaporisation latent heat to the fumes of the boiler to yield the same as heat to the system water thus improving the combustion efficiency.

Description

BOILER CONDENSATION MODULE

The present invention relates to a boiler condensation module.

More specifically, the invention relates to a device of the above kind that, when installed inside, or connected with, a methane- or G. P. L.-, or Diesel oil- fed heating boilers, or with another kind of boiler, picks up the exhaust fumes from the combustion, positively exploiting the residual heat.

At present, most used boilers are the so-called "high-efficiency boilers". These apparatuses can exploit up to a 95% of the combustible calorific power, loosing only 5% of the total heat. They are used for feeding high temperature systems, i.e. systems employing standard radiators and/or fan coils, i.e. elements requiring, for a proper operation, a thermal vector (water) with temperatures above 70⁰C. Said boilers cannot recover combustion latent heat of vaporisation, i.e. heat that would be recovered transforming vapour produced during the combustion into liquid form.

Some of the most important gas boiler manufacturers produce the "condensation boilers", i.e. particular boilers that, by a normally upset, particular burner, and one increased efficiency smoke/water heat exchanger, can bring the combustion fumes under the so-called "dew point" varying between 25⁰C and 55°C (that can vary on the basis of the combustible, of the air-combustible mixture and of the CO₂ emitted); under said temperature, vapour contained within the fumes starts condensing, thus yielding a great amount of heat. It is important underlying that latent condensation heat is equal to 11 % of the total heat from the methane combustion. For this reason, without any dispersion, a condensation boiler can theoretically have a calorific efficiency of 111% with respect to the calorific power (100% sensitive heat + 11% condensation latent heat).

However, these apparatuses reach very high efficiencies of 103% - 106% only if employed in low temperature systems (floor coils) with a temperature of the circulating thermal vector (water) of 35°C - 4O⁰C, or applying some specific solutions (reducing the temperature and/or flow rate of the thermal vector, limiting the boiler power). Anyway, if the temperature of these boilers is kept at a value of 6O⁰C - 8O⁰C (necessary to make a system with radiators or fan coils working properly) the condensation boiler does not succeed recovering the vaporisation latent heat since water inlet temperature is higher or too close to the fume dew temperature: in this case, condensation boiler operates as a standard high efficiency boiler (efficiency 85% - 95%).

In view of the above, it is suggested according to the present invention an apparatus permitting to recover part of the sensitive heat and part of the condensation latent heat (also known as vaporisation latent heat) contained within the large vapour amounts produced by the combustion.

Heat recovered by the described apparatus will be used to preheat the thermal vector contained within the tubes of the heating system (usually water) that, from the final users (radiators, ventilation - convectors, radiating tubes, ecc) enters again within the boiler to be then heated and sent again to the final users (but it is also possible use the same for other applications). This permits that the boiler uses less energy to increase the thermal vector at the set temperature, thus obtaining a saving of fuel with the same energy obtained from the system.

Apparatus according to the invention employs a water/fume exchanger with a compression thermodynamic cycle allowing recovering a high amount of heat until cooling the fumes (even up to about +35⁰C) and transferring said heat to the thermal vector with a different temperature (even beyond + 80⁰C).

It is therefore specific object of the present invention a boiler condensation module, characterised in that it comprises a water/fume heat exchanger and a closed circuit compression thermodynamic frigorific apparatus, said module being communicated with a boiler intercepting the flow of the fumes and the flow of the water, in order to subtract sensitive heat and vaporisation latent heat to the fumes of the boiler to yield the same as heat to the system water thus improving the combustion efficiency.

Preferably, according to the invention, said heat exchanger is of the water/fume plate or laminar unit type.

Furthermore, according to the invention, said frigorific apparatus is a compression thermodynamic frigorigen apparatus, particularly, comprised of a fume-refrigerant or evaporator heat exchanger, of an exchanger, of a refrigerant compressor, of a expansion or lamination member, of a control electric - electronic system.

Still according to the invention, said closed circuit compression thermodynamic frigorific apparatus provides an evaporation temperature included between 12°C and 20⁰C and a condensation temperature variable between 50⁰C and 95°C.

Particularly, said frigorigen machine comprises one or more water - refrigerant heat exchanger of the plate and/or laminar unit and/or tube bundle type; one or more fume - refrigerant heat exchangers of the plate and/or laminar unit and/or tube bundle type; one or more compressors, even of the inverter type, suitable to compress R12, R134, R404, R407, R410, R125 refrigerant fluids and like as heat; one or more lamination members of the capillary and/or thermostatic expansion valve type, with or without pressure equaliser and/or calibrated choke; metallic tubes connecting the various components.

Furthermore, according to the invention, parts that can be directly in touch with the fume condensate are comprised of material resisting to the acid corrosion due to the same condensate, e.g. AISI 316L stainless steel, or other suitable materials.

Still according to the invention, one or more water/fume plate or laminar unit type heat exchangers are provided, with or without the thermal exchange with the carburant air.

Further, according to the invention, said water - fume heat exchanger and said fume - refrigerant heat exchanger (evaporator for the frigorific circuit) are installed inside a metallic room within which fumes circulate, realised in such a way that condensate produced by the two heat exchangers can easily outflow outside said metallic room, avoiding that a mixing of air, environment, water and fumes occurs. Furthermore, protection and control fittings are provided, that are usually used in frigorific circuits such as: pressure switches, thermostats, flow-meters, manometers, thermometers, transducers, fume extractors, passage indicators, fans, liquid injection systems, liquid receivers and dividers, filters, electric/electronic boards, pressure equalisers and reducers, interception and adjustment valves, mixing valves, condensate exhaust siphons.

Particularly, fluid R134A is employed as refrigerant fluid, or, as alternative, various refrigerant fluids can be employed (R404, R407, R410, R125) circulating within the frigorific circuit. Still according to the invention, a volumetric or centrifugal compressor of the hermetic, semi-hermetic or open type is provided. Always according to the invention, another fluid or a mixture comprising glycol or another anti-freezing liquid is used instead of water as thermal vector of the system.

Furthermore, according to the invention, transfer (transmission) of the heat recovered from the fumes occurs to the fluid of another system not directly connected with the system of the main water, for example for heating the sanitary heat water and/or for feeding another heating system and/or for directly heating air.

Finally, according to the invention, counter current flow heat exchangers can be used.

"Condensation boiler module" according to the present invention aims obtaining for a standard high efficiency boiler (not a condensation boiler) the same advantages of a condensation boiler (low consumption, very high efficiency and low emissions), and at the same time solving the two main drawbacks: high costs and good operation only with low water temperature within the system.

Apparatus according to the invention permits recovering condensation latent heat, even maintaining a high temperature of the thermal vector (6O⁰C - 80⁰C). This permits avoiding expensive modifications of the system for delivering the thermal vector and of the final devices (radiators - fan coils) that would be necessary in case of installation of a condensation boiler on an already existing heating system.

Only a small percentage of the existing heating systems is realised with a floor diffusion, while at present 95% of systems are provided with cast iron or aluminium radiators, where the provision of a condensation boiler is not convenient.

The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein: figure 1 is a schematic view of a boiler provided with a condensation module according to the invention; and figure 2 particularly shows the condensation module of figure 1.

Observing the enclosed figures, it is shown a boiler 1, with a condensation unit 2 according to the invention. As shown in figure 1 for exemplificative purposes, module according to the invention can be applied as outer component according to the scheme boiler 1 , boiler condensation module 2, radiators 3, water delivery tubes 4 to the users, water return tubes 5 from the users, boiler fume exit 6, flue 7, condensate exhaust 8.

Observing particularly figure 2, it is shown a condensation module 2 for a boiler according to the invention, substantially comprising a water/fume plate or laminar unit type heat exchanger E and a frigorific apparatus of the compression thermodynamic type.

Said frigorigen apparatus is comprised of a fume-refrigerant or evaporator heat exchanger G (evaporator), of a refrigerant compressor H, of an expansion or lamination member L, of a control electric - electronic system and of various functional fittings usually used in the frigorific systems, that are not specific object of the present invention.

Fumes arriving from the boiler (not shown), enter within the boiler condensation module 2, into the metallic room P through the hole C, at a temperature of about 150°C, meeting in sequence the fume/water heat exchanger E, where, due to the thermal exchange with water, cools up to 90⁰C, and then, the fume-refrigerant heat exchanger G, where they are further cooled, since refrigerant circulates at a temperature lower than 20⁰C.

Fumes cool in this heat exchanger G up to about 35⁰C, thus permitting that vapour contained in the same condenses with the consequent recover of the vaporisation latent heat.

Finally, fumes exit from the metallic room P through the hole D, possibly pushed by the fan/extractor N compensating the higher flow resistance and the lack of draft due to the low temperature. Water coming from the system at about 60⁰C enters through joint A, passes first within the water - refrigerant heat exchanger F, thus being pre-heated up to about 62 - 64°C due to the high temperature of the refrigerant (about 11O⁰C), and then passes within the water - fume heat exchanger E, further heating (possibly up to 64°C - 67⁰C), since it exchanges heat with fumes up to 150⁰C.

Finally, water exits from the boiler condensation module by joint B through tube Q. Under standard conditions, said pre-heated water is destined to go back into the boiler, that will require less fuel to increase the temperature just for the previous pre-heating. Refrigerant (usually R134A or a similar fluid) is contained in a watertight circuit. Compressor H compresses fluid as vapour at a pressure (16 - 22 bar) necessary to obtain that the vapour has the water temperature when entering again within the final users.

Overheated vapour enters within the water - refrigerant heat exchanger F through the high-pressure tube I; refrigerant yields heat to water, said water heating while refrigerant cools under its saturation temperature (referred to its specific pressure) changing state and becoming in liquid form. Now, refrigerant meets the lamination member L, aiming to reduce its pressure (about 3.5 - 4.5 bar) in order to lower its saturation temperature (12°C - 18°C) and at the same time its real temperature.

Thus, refrigerant is in a liquid - vapour saturated mixture state and, through the low pressure tube M, enters within the fume - refrigerant heat exchanger G; here, refrigerant receives heat from fumes (cooling up to 35°C - 40⁰C) permitting state passage into vapour of the remaining liquid part of the refrigerant. Refrigerant is thus sucked by compressor H to start again the cycle.

"Boiler condensation module" according to the invention can be installed within a forced draught boiler or into a blown air burner during its manufacturing or it can be provided in an already existing heating system, intercepting boiler fumes and the boiler inlet water tube.

Condensation of fumes occurs only inside the module 2 thus preserving boilers with respect to damages due to the condensate acidity.

It is well evident that recovered heat can be used for different objects with respect to that or pre-heating water for the boiler. "Boiler condensation module" according to the invention can be realised for different powers in order to be suitable for boilers having different sizes and employing different fuels. In fact, also the type of fuel influences the power of the inventive solution since, with the same lower calorific power, the upper calorific power is not the same. "Boiler condensation module" according to the invention has the advantage of transforming a standard boiler into a very high efficiency boiler thanks to the almost complete recover of the heat (sensitive and latent heat) usually dispersed into the atmosphere. In fact, without wasting energy, consumption of fuel is reduced at the minimum level, as well as the emissions are proportionally reduced with respect to the reduction of fuel consumption. Polluting substances are further kept into the condensation water formed during the operation both because some components are soluble and because of the specific surface-active power of the same condensation water. By the operation of the system with inlet water warmer than

35°C, boiler provided with "boiler condensation module" has efficiency higher than the traditional condensation boilers. Boiler condensation module is cheap and simple to realise and allows obtaining a very interesting performance/price ratio. The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.

Claims

1. Boiler condensation module, characterised in that it comprises a water/fume heat exchanger and a closed circuit compression thermodynamic frigorific apparatus, said module being communicated with a boiler intercepting the flow of the fumes and the flow of the water, in order to subtract sensitive heat and vaporisation latent heat to the fumes of the boiler to yield the same as heat to the system water thus improving the combustion efficiency.

2. Boiler condensation module according to claim 1 , characterised in that said heat exchanger is of the water/fume plate or laminar unit type.

3. Boiler condensation module according to one of the preceding claims, characterised in that said frigorific apparatus is a compression thermodynamic frigorigen apparatus.

4. Boiler condensation module according to claim 3, characterised in that said frigorific apparatus is comprised of a fume- refrigerant or evaporator heat exchanger, of an exchanger, of a refrigerant compressor, of a expansion or lamination member, of a control electric - electronic system.

5. Boiler condensation module according to one of the preceding claims, characterised in that said closed circuit compression thermodynamic frigorific apparatus provides an evaporation temperature included between 12°C and 2O⁰C and a condensation temperature variable between 50⁰C and 95°C.

6. Boiler condensation module according to one of the preceding claims, characterised in that said frigorigen machine comprises one or more water - refrigerant heat exchanger of the plate and/or laminar unit and/or tube bundle type; one or more fume - refrigerant heat exchangers of the plate and/or laminar unit and/or tube bundle type; one or more compressors, even of the inverter type, suitable to compress R12, R134, R404, R407, R410, R125 refrigerant fluids and like as heat; one or more lamination members of the capillary and/or thermostatic expansion valve type, with or without pressure equaliser and/or calibrated choke; metallic tubes connecting the various components.

7. Boiler condensation module according to one of the preceding claims, characterised in that parts that can be directly in touch with the fume condensate are comprised of material resisting to the acid corrosion due to the same condensate, e.g. AISI 316L stainless steel, or other suitable materials.

8. Boiler condensation module according to one of the preceding claims, characterised in that one or more water/fume plate or laminar unit type heat exchangers are provided, with or without the thermal exchange with the carburant air.

9. Boiler condensation module according to one of the preceding claims, characterised in that said water - fume heat exchanger and said fume - refrigerant heat exchanger (evaporator for the frigorific circuit) are installed inside a metallic room within which fumes circulate, realised in such a way that condensate produced by the two heat exchangers can easily outflow outside said metallic room, avoiding that a mixing of air, environment, water and fumes occurs.

10. Boiler condensation module according to one of the preceding claims, characterised in that Furthermore, protection and control fittings are provided, that are usually used in frigorific circuits such as: pressure switches, thermostats, flow meters, manometers, thermometers, transducers, fume extractors, passage indicators, fans, liquid injection systems, liquid receivers and dividers, filters, electric/electronic boards, pressure equalisers and reducers, interception and adjustment valves, mixing valves, condensate exhaust siphons.

11. Boiler condensation module according to one of the preceding claims, characterised in that Particularly, fluid R134A is employed as refrigerant fluid, or, as alternative, various refrigerant fluids can be employed (R404, R407, R410, R125) circulating within the frigorific circuit.

12. Boiler condensation module according to one of the preceding claims, characterised in that a volumetric or centrifugal compressor of the hermetic, semi-hermetic or open type, is provided.

13. Boiler condensation module according to one of the preceding claims, characterised in that another fluid or a mixture comprising glycol or another anti-freezing liquid is used instead of water as thermal vector of the system.

14. Boiler condensation module according to one of the preceding claims, characterised in that transfer (transmission) of the heat recovered from the fumes occurs to the fluid of another system not directly connected with the system of the main water, for example for heating the sanitary heat water and/or for feeding another heating system and/or for directly heating air.

15. Boiler condensation module according to one of the preceding claims, characterised in that counter current flow heat exchangers are used.

16. Boiler condensation module according to one of the preceding claims, substantially as illustrated and described.