WO1991012468A1

WO1991012468A1 - Boiler

Info

Publication number: WO1991012468A1
Application number: PCT/GB1990/000173
Authority: WO
Inventors: Peter Joseph Padley; Felicity May Padley; Hartmut Max Rodde
Original assignee: Peter Joseph Padley; Felicity May Padley; Hartmut Max Rodde
Priority date: 1988-09-22
Filing date: 1990-02-06
Publication date: 1991-08-22
Also published as: GB2223838A; GB8822356D0; GB2223838B

Abstract

A boiler has a burner (5) supplied with a fuel/air mixture which burns in a combustion zone (17); a series of heat exchanger banks (2) are located adjacent the combustion zone, through which a working fluid passes. The working fluid further passes along fluid communication conduits (6) provided in the structure of the burner (5) before exiting the boiler.

Description

Bo i l er

The present invention relates to boilers and particularly to boilers for domestic or industrial heating appl ications.

According to the invention, there is provided a boiler which comprises a) a burner comprising a heat transfer matrix, which heat transfer matrix comprises a plurality of conduits arranged to carry a working fluid, and a second matrix of passageways for the communication therethrough of a fuel and air mixture from a fuel and air inlet zone to a combustion zone, said second matrix of passageways and said conduits being in direct thermal contact with one another. b) heat exchange means for transfer of heat from flue gases produced in said combustion zone to said working fluid, c) means for permitting communication of said working fluid between said heat exchange means and said heat transfer matrix, and d) inlet and outlet means provided such that a flow path is defined for said working fluid from said inlet means to said outlet means via, in sequence, said heat exchange means and said heat transfer matrix.

It is preferred that the conduits are elongate and disposed substantially parallel to one another, advantageously having their longitudinal axes substantially normal to the general direction of flow of the working fluid in the burner. Preferably the matrix of passageways comprises discrete rows of passageways arranged intermediate adjacent conduits. Advantageously each of these rows is formed of a unitary member shaped so as to define the passageways, the unitary member being, for example, (i) a metallic sheet arranged in 'concertina like' form so as to define the passageways, or (ii) plane, closely-spaced parallel metallic sheets through which pass the plurality of conduits carrying the working fluid.

It is preferred that a mixing zone for mixing of the fuel and air is provided substantially within the boiler.

Preferably the fuel is substantially gaseous, and advantageously may be introduced into the boiler by means of a driven fan. which fan is preferably located in the region of the inlet zone, where it has the additional advantage of assisting the mixing of the fuel and air. Advantageously, restricting means is provided for the burner, arranged to restrict the number of passages through which the fuel and air mixture communicates between the inlet and the combustion zones.

It is preferred that the heat exchange means comprises a plurality of heat exchanger banks, which are preferably mounted substantially parallel and adjacent one another. In this case, it is preferred that the direction of flow of the working fluid leaving each of the heat exchanger banks is substantially opposed to the direction of flow of the working fluid entering an adjacent heat exchanger bank.

For reasons of efficiency of construction the heat exchanger banks may be of substantially identical construction to the burner, and may be fabricated as a substantially integral unit, preferably of welded or brazed metal.

Preferably the working fluid employed in the boiler according to the invention is aqueous.

It is preferred that the boiler is capable of being fired in a vertical orientation, but it may also be fired advantageously in a horizontal orientation with a view to conservation of space.

The invention will be further described in a particular embodiment, by way of example, with reference to the accompanying drawings in which:

Figure 1 is a schematic view of an exemplary boiler according to the invention;

Figure 2 is a schematic view of an alternative boiler according to the invention; and

Figure 3 is a perspective view of a burner used in the boilers of Figure 1 or Figure 2.

Referring to Figures 1 and 2, in which like components are denoted by like reference numerals, a boiler of welded or brazed metal construction has a number has a number of layers of conventional heat exchanger banks 2 through which pressurised feed water is passed via an inlet port 3.

The feed water progresses through successive layers of heat exchanger banks via communicating headers 4 located at the ends of adjacent banks 2 which are arranged to facilitate opposed directions of flow in adjacent layers of heat exchanger banks. The flow path of the feed water (shown by arrows) is such that passes through successive layers of heat exchanger banks causes the feed water to rise in temperature as it approaches the combustion chamber 17.

Referring now to Figure 3, the burner has a row of feed water ducts 6 which extend between header portions 7 and 8. The header 8 is communicatively connected to the^' downstream end 9 of the uppermost heat exchange bank 2, by a connecting conduit 10. Thus, the feed water passes from the heat exchanger banks via the conduit 10, to the header 8, where it is then forced through the ducts 6 in the burner to the header 7 before passing via a further communication conduit 11 to an outlet port 12.

The burner 5 has set in between the feed water ducts 6 an open at both ends heat conduction matrix in the form of sheets of concertina-like thin metal strips 13 arranged to ^"be in thermal contact with adjacent feed water ducts 6.

Air 23 and gas 24 is introduced to the boiler, by means of a fan 14, entering a plenum chamber 15 wherein the air and gas mixes. The fan 14 forces the premixed air and gas mixture 25 through the open-ended heat conduction matrix of metal strips 13, where it burns on the downstream side 16 of the burner 5. Conventional ignition apparatus (not shown) may be fixed to an internal wall of the combustion chamber 17, and a viewport 20 is situated in such a wall facilitating visual observation that combustion is taking place.

The flame is anchored to the combustion chamber facing edges of the external walls of the feed water ducts 6,

SUBSTITUTE SHEET and also to the combustion chamber facing edges of the metal strip heat conduction matrix 13. The flame seat area is adjustable as required by the plates 18 which may be upstream and/or downstream of the burner 5.

Heat of combustion is therefore transferred from the flame seat, through the metal heat conduction matrix 13 and the walls of the feed water ducts 6 of the burner, to the feed water in the ducts 6. This has the two fold advantage of enabling a significant amount of the heat energy of combustion produced in the boiler to be transferred to the feed water, and also cooling the burner 5 thus ameliorating overheating of the boiler (particularly of the burner) and its associated, problems such as burner distortion and cracking of fuel molecules.

The boiler according to the invention has further advantages rwelative to known boilers, such as high combustion intensity; efficient combustion characteristics permitting a short combustion chamber and producing flue gases containing negligible pyrolysis products and carbon monoxide; and favourable flashback and turndown ratio.

In appropriately modified forms the boiler may be used in condensing or non-condensing mode and may be fired adequately in any orientation not exclusively in a downward firing mode as described above. Additionally the fan 14 which introduces the air/gas mixture into the boiler may be of the axial flow type as shown in Figure 1, or of the radial flow type as shown in Figure 2.

SUBSTITUTE SHEET

Claims

Cla ims :

1. A boiler which comprises a) a burner comprising a heat transfer matrix, which heat transfer matrix comprises a plurality of conduits arranged to carry a working fluid, and a second matrix of passageways for the communication therethrough of a fuel and air mixture from a fuel and air inlet zone to a combustion zone, said second matrix of passageways and said conduits being in direct thermal contact with one another, b) heat exchange means for transfer of heat from flue gases produced in said combustion zone to said working fluid, c) means for permitting communication of said working fluid between said heat exchange means and said heat transfer matrix, and d) inlet and outlet means provided such that a flow path is defined for said working fluid from said inlet means to said outlet means via, in sequence, said heat exchange means and said heat transfer matrix.

2. A boiler as claimed in claim 1, wherein said conduits are elongate and disposed substantially parallel to one another.

3. A boiler as claimed in any claim 1 or 2, wherein said passageways are elongate having their longitudinal axes substantially normal to the general direction of flow of said working fluid in said burner.

SUBSTITUTE SHEET dS claimed in any preceding claim. matrix of passageways comprises discrete rows of passageways arranged intermediate adjacent conduits comprising said heat transfer matrix.

5. A boiler as claimed in any preceding claim, wherein a mixing zone for mixing of said fuel and air is provided substantially within said boiler.

6. A boiler as claimed in any preceding claim, wherein a driven fan is provided in the region of said inlet zone for introducing said fuel and air mixture into said boiler.

7. A boiler as claimed in any preceding claim, wherein said burner is provided with means for restricting the number of passages through which said fuel and air mixture can communicate between said inlet zone and said combustion zone.

8. A boiler as claimed in any preceding claim, wherein said heat exchange means comprises a plurality of heat exchanger banks, said banks being preferably mounted substantially parallel and adjacent one another.

9. A boiler as claimed in claim 8, wherein the direction of flow of said working fluid leaving each of said heat exchanger banks is substantially opposed to the direction of flow of said working fluid entering an adjacent heat exchanger bank.

10. A boiler as claimed in claim 8 or 9, wherein each of said banks is of substantially identical construction to said burner.

SUBSTITUTE SHEET