EP2051007A1

EP2051007A1 - Economiser/environmentally-friendly device to be used in combustion heating appliances

Info

Publication number: EP2051007A1
Application number: EP07020214A
Authority: EP
Inventors: Robert Dal Pra'
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-16
Filing date: 2007-10-16
Publication date: 2009-04-22

Abstract

Economiser/environmentally-friendly device to be used in combustion heating appliances, especially for domestic use, such as combustion heaters and fireplaces, provided with boiler equipped with biomass (wood, pellets, wood chips, oil seeds and the like) burners. Such device is characterised in that it comprises at least one catalyst (2), at least one heat exchanger (3,4), at least one electrostatic filter (5) and at least one suction device (6), which has the function of generating reduced pressure along the path of the fumes (burner - catalyst - heat exchanger - filter).

Description

The present finding regards an economiser/environmentally-friendly device to be used in combustion heating appliances according to the introduction of claim 1.
It is well known that the main problem regarding use of heating appliances, especially domestic appliances such as combustion heaters and fireplaces provided with boiler equipped with biomass (wood, pellet, wood chips, oil seeds and the like) burners, concerns obtaining maximum thermal performance (recovery of the combustion heat) with minimum pollution (least emission of combustion dusts into the atmosphere).
According to the current techniques, there are several heater and fireplace performance enhancement methods. Some of these methods include creating airflows in the fire chamber thus enhancing combustion and consequently reducing emissions (see patents No. VI93A000161 and No. VI99A000183). Alternatively, the heating appliance can be equipped with a chamber with a secondary airflow or a water coil which, in contact with the combustion exhaust fumes, transfers some of the heat of the aforesaid fumes to the vector fluid, thus increasing the appliance's thermal performance (for example as described in the V199A000243 and VI2004A000049 patents).
The object of the present finding is to make a combustion heating appliance which can function with a considerably improved energy performance and lowered pollution emissions with respect to similar products of known type.
This can be achieved by means of a device to be mounted downstream of a biomass burner, present in wood, pellet, wood chips, oil seeds and generally biomass heaters/boilers, which comprises at least one impregnated, monolithic honeycomb catalyst, at least one heat exchanger, at least one electrostatic filter and at least one suction device, which has the function of generating a depression along the fumes path (burner - catalyst - heat exchanger - filter) to facilitate their elimination from the appliance.
Structurally, the device of the finding is substantially made up of a post-burner positioned downstream of the combustion chamber of the heating appliance, as it must collect burnt gases while they are still flames and at temperatures not below 300-350°C, the limit value for being able to neutralise the substances by means of the catalyst.
The catalyst has the task of converting harmful substances into harmless substances by means of chemical reactions where noble metals such as platinum and palladium cause the oxidation of carbon monoxide and unburnt hydrocarbons, converting them into carbon dioxide and water (environmental function).
In addition, when the gases generated by combustion pass through the catalyst, not only do they undergo a chemical conversion, but they also trigger a post-combustion process of the gases which remained unburnt during the first phase, resulting in a considerable increasing (up to 800°C) of the fumes exiting from the aforesaid catalyst (energy function).
Then, the aforesaid considerably hot gases exiting from the catalyst cross through a heat exchanger, so to be able to recover most of the heat possessed by the post-combustion gases. This heat exchanger is used to produce water or hot air for the environment.
The positioning of the heat exchanger, after the catalyst, allows achieving a high performance, since the hot gases coming from the combustion stage - though collected directly above the burner and thus containing high quantities of harmful substances - due to the post-combustion achieved with aforesaid the catalyst are free of fumes containing ashes at the outlet of the catalyst itself. If said ashes still present during the use, they would disadvantageously deposit on the inner walls of the exchanger, thus reducing its performance or thermal conduction towards the outside.
The finding moreover provides that the exchanger be positioned such that a first part thereof at the base of the tube bundle is touched by the combustion flames, which causes the immediate and complete evaporation of possible condensate that is formed on the bottom of the aforesaid exchanger.
Subsequently, the hot gases, free of condensate, pass through the second section of the heat exchanger tube bundle transferring the residual heat to the outside.
Likewise, the gases exiting from the exchanger at low temperatures pass through an electrostatic chamber where they undergo a filtration process which retains any dusts and fumes generated by poor post-combustion due to an irregular functioning of the heating appliance, such as a sudden temperature drop inside the catalyst, or during the burner turning on/off steps.
Lastly, a suction device is mounted at the end of the exhaust gas pipe where the fumes have completely cooled down. Such suction device is used to place the entire channel which defines the whole exhaust gas path under reduced pressure (catalyst/heat exchanger/electrostatic chamber), so to initiate the suction operation directly from the heating appliance combustion chamber.
From a practical standpoint, laboratory tests have proven that upon final exit, not only are the exhaust gases free of polluting dusts (environmental effect) but they also reach a maximum temperature of 100°C, given that at this point they have transferred a considerable amount of their heat (economiser effect).
This invention shall be better defined by means of the description of a possible embodiment thereof, given as an illustrative but not limiting example, with reference to the attached drawings, wherein:
figures 1-3 (table I) illustrate three views, respectively one front and two side views, of the device according to the finding mounted on a heating appliance;
figures 4-5 (table II) illustrate two views, respectively front and side, of the device according to the finding;
figures 6-7 (table III) illustrate two views, front and side, of the front part of the device according to the finding;
figures 10-12 (table V) illustrate three orthogonal views of the air conveying device.
As illustrated in fig. 1, the economiser/environmentally-friendly device according to the finding, indicated as 1, is mounted on the combustion chamber "C" of a standard heating appliance, not illustrated for simplification reasons.
As illustrated in figures 1-3, the device 1 is characterised in that it provides for the use of four components: a catalyst 2, a first heat exchanger 3, a second heat exchanger 4, an electrostatic filter 5 and a suction device 6.
As illustrated in figures 4 and 5, the previously mentioned components are positioned in sequence along the exhaust gas route, from the combustion chamber "C" to the exhaust pipe "S". Furthermore, said components are connected with each other through pipes, respectively pipe 7 connecting the catalyst 2 to the first exchanger 3, pipe 8 connecting the first exchanger 3 to the second exchanger 4 and pipe 9 connecting the electrostatic filter 5 to the final suction device 6.
Operatively, the device 1 provided for by this invention operates in two steps: there is the first step where post-combustion of exhaust gases occurs and where a considerable heat exchange activity between said gases and the environment takes place; then, a second step closely follows where the heat exchange activity is completed and the exhaust gases filtering operations are performed.
As illustrated in figures 6 and 7, in the first operation step the exhaust gases "G1" - see arrows - find their way from the combustion chamber "C" into the catalyst 2 positioned in the aforesaid chamber, such that its inlet mouth 2.1 can be reached by the flames coming from the appliance burner. Thus incoming gases reach the highest temperature possible (not below 300-350°C in any case) hence allowing proper functioning of the aforesaid catalyst.
A post-combustion process occurs in the catalyst 2 - preferably of ceramic, monolithic honeycombed type and impregnated with noble metals - so that not only are the exiting gases "G2" free of harmful substances but they also reach a temperature of approximately 800°C.
By means of pipe 7, gases enter into the heat exchanger 3 where, in contact with the tube bundle 3.1, the first heat exchange with the environment occurs through air or water circulation.
As illustrated in fig. 6, the finding provides that the base 3.2 of the exchanger 3 faces the combustion chamber "C", so to be able be touched by the combustion flames, so that the possible condensate which is formed on the tube bundle 3.1 is collected at the base 3.2 and vaporised completely by the heat (see arrows) generated by the combustion chamber.
As illustrated in figures 7 and 8, the gases "G3", still hot and dry, exiting from the exchanger 3 and collected by the channel 3.3, are conveyed through pipe 8 into the second exchanger 4 where, in contact with the tube bundle 4.1, a second heat exchange with the environment occurs through air or water circulation.
Gases "G4", already cooled to low temperature at this point, at the outlet of the tube bundle pass through the electrostatic filter 5, comprising at least one ionising chamber 5.1 and at least one collection chamber 5.2, which remove all residual pollutant dusts from the aforesaid gases.
Lastly, through pipe 9, the gases G5 are suctioned through a suction device 6 which provides the final discharge through the mouth S.
As illustrated in figures 9-11, in order to increase the thermal performance of the appliance according to the finding, the mounting is envisaged of an air conveying apparatus, generally indicated as 10, on the first exchanger 3. Said air conveying device 10 comprises at least a covering 10.1 coupled with an electric fan 10.2 - which draws air from the outside and sends it into the tube bundle 3.1 - and an outlet grate 10.3.
Alternatively, especially regarding the second exchanger 4, thermal exchange may occur through a water (or any other liquid) forced circulation system by means of a hydraulic pump.
The descriptions above show the operative advantages attained with the use of the device according to the finding. In particular, it is possible to perform heat exchange and combustion exhaust gas purification operations with minimum encumbrance and maximum performance.
Of course, different embodiments are possible, also different from that described here, as a function of the size and type of components used, without departing from the protective scope of the following claims.

Claims

ECONOMISER/ENVIRONMENTALLY-FRIENDLY DEVICE TO BE USED IN COMBUSTION HEATING APPLIANCES, especially for domestic use, such as combustion heaters and fireplaces provided with boiler equipped with biomass (wood, pellets, wood chips, oil seeds and the like) burners,
said device (1) is characterised in that it includes at least one catalyst (2), at least one heat exchanger (3,4), at least one electrostatic filter (5) and at least one suction device (6), which has the function of generating reduced pressure along the path of the fumes (burner - catalyst - heat exchanger - filter).
DEVICE, according to claim 1, characterised in that it functions as a post-burner and is positioned immediately downstream of the heating appliance combustion chamber (C).
DEVICE, according to claim 2, characterised in that the catalyst (2) is of honeycomb, monolithic type, impregnated with noble metals such as platinum and palladium which cause the oxidation of carbon monoxide and other unburnt hydrocarbons, converting them into carbon dioxide and water.
DEVICE, according to claim 3, characterised in that the exchanger (3,4) is positioned in such a manner that a part thereof is touched by the combustion flames, in order to cause the evaporation of the condensate forming which forms on the bottom of the aforesaid heat exchanger.
DEVICE according to claim 4 characterised in that the electrostatic filter (5) performs filtration operations which retain possible dusts and fumes generated by poor post-combustion, due to an irregular functioning of the heating appliance, such as a sudden temperature drop inside the catalyst (2), or during the burner turning on/off steps.
DEVICE, according to one or more of the previous claims, mounted on the combustion chamber (C) of a standard heating appliance, characterised in that said device requires the use of a catalyst (2), a first heat exchanger (3), a second heat exchanger (4), an electrostatic filter (5) and a suction device (6) and where the aforesaid components are positioned in sequence along the exhaust gas route, from the combustion chamber (C) to the exhaust pipe (S) and connected with each other through pipes, respectively pipe (7), which connects the catalyst (2) to the first exchanger (3), pipe (8), which connects the first exchanger (3) to the second exchanger (4), and pipe (9), which connects the electrostatic filter (5) to the final suction device (6).
DEVICE, according to claim 6, characterise in that the catalyst (2) is positioned in the aforesaid combustion chamber such that the inlet mouth (2.1) can be reached by the flames of the appliance.
DEVICE, according to claim 7, characterised in that gases enter into the exchanger (3) where, in contact with the tube bundle (3.1), the first heat exchange with the environment occurs through water or air circulation.
DEVICE, according to claim 8, characterised in that the base (3.2) of the exchanger (3) is positioned above the combustion chamber (C), so to be able to be touched by the combustion flames, so that the possible condensate which forms on the tube bundle (3.1) is collected on the base (3.2) and completely vaporised by the heat generated in the combustion chamber.
DEVICE, according to claim 9, characterised in that in the exchanger (4), in contact with the tube bundle (4.1), a second heat exchange occurs with the environment through air or water circulation.
DEVICE, according to claim 10, characterised in that the electrostatic filter (5) is composed of at least one ionising chamber (5.1) and at least one collection chamber (5.2) which remove any residual pollutant dusts from the aforesaid gases, after post-combustion and heat exchange.
DEVICE, according to claim 11, characterised in that on the first exchanger (3), there is an air conveying device (10), comprising a covering (10.1), coupled with an electric fan (10.2) which draws air from the outside and sends it into the tube bundle (3.1), and an outlet grate (10.3).
DEVICE, according to one or more of the previous claims, characterised in that the heat exchange is achieved by means of water or any other liquid driven by a hydraulic pump.
HEATING APPLIANCES, such as heaters/boilers fuelled by wood, pellet, wood chips, oil seeds and biomass in general, characterised in that they are equipped with the economiser/environmentally-friendly device (1) in accordance with the preceding claims.