IES20070603A2 - Improvements to boilers - Google Patents

Abstract

A boiler (10) for a fan assisted burner has a base (20), a top plate (22) and four sidewalls (12,14,16) extending between the base (20) and the top plate (22). One or more of the side walls (12,14,16) is of hollow construction so as to act as heat exchangers. Fins (50) are fixed to the inner surfaces of the side walls (12,14,16). Baffle plates (40,41,42,43) are engaged with fins (50). Support legs (60) and tab (62) are provided between the baffle plates (40,41,42,43) and the fins (50) so as to generate an elongate gap. Combustion and flue gases emanating from the combustion chamber extend through the elongate gaps between the fins (50), baffle plates (40,41,42,43) and side walls (12,14,16) to provide heat transfer to the water passageways. <Figure 2>

Description

The present invention relates to improvements to boilers, in particular boilers used as heat exchangers in heating installations, such as oil fired boilers.

In order to increase the efficiency of oil fired boilers, there are numerous boilers on the market which have increasingly complex internal baffle arrangements and tortuous passageways for the flue gases to follow. Such baffle arrangements require regular maintenance in order to keep the passageways clear of soot, debris and deposits. Also, they require the use of oil-fired burners with high pressure fans in order to drive the gases through the passageways. There is therefore a need for a boiler which is easy and inexpensive to manufacture, provides good heat transfer and does not generate a large back pressure for a fan.

The present invention provides a boiler for a fan assisted burner, the boiler being of generally rectangular construction having a base, a top plate, four sidewalls extending between the base and the top plate, one or more of the side walls being of hollow construction so as to act as heat exchangers for water flowing through the hollow side walls, a plurality of fins being fixed to the inner surfaces of the side walls, one or more transverse baffle plates engaged with the fins, spacer means being provided between the baffle plates and the fins so as to generate an elongate gap between the baffle plates and the two opposing side walls and the rearmost side wall, whereby combustion and flue gases emanating from the combustion chamber extend through said elongate gaps between the fins, baffle plates and side walls to provide heat transfer from the combustion and flue gases to the water passageways.

Ideally, the fins are welded to the side walls of the boiler so as to provide for good thermal transfer.

Preferably, the transverse baffle plate nearest the base is provided with a Vshaped formation which, in use of the boiler, deflects the fire ball produced by a burner installed in the boiler, and a slot is formed at each side of the baffle plate so IE 07 0 60 3 that the flue gases can escape at the sides of the baffle plate adjacent the side walls of the boiler.

Advantageously, the spacer means provided between the baffle plates and the fins 5 comprises four support legs on each baffle plate and a spacing tab at the back edge of each baffle plate.

The invention will hereinafter be more particularly described with reference to the accompanying drawings which show, by way of example only, one embodiment of a boiler according to the invention. In the drawings: Figure 1 is a perspective view from the front and one side of the boiier; and illustrating the passage of combustion gases at one side of the boiler; Figure 1A is a second perspective view from the front of the boiler; Figure 2 is a front view of the boiler illustrating the passage of combustion gases at two sides of the boiler; Figure 3 is a perspective view of four baffle plates used in the boiler; Figure 4 is a front view of the four baffle plates; Figure 5 is an exploded perspective view from one side of the main components of the condensing apparatus for mounting on the boiler; and Referring to the drawings, the boiler 10 comprises a left hand side wall 12, a rear side wall 14 and a right hand side wall 16 and an access door (not shown for clarity purposes). The side walls 12, 14 and 16 include hollow passageways for conducting water for a heating system. The boiler also includes a base 20 and a top plate 22 which has an outlet port 24 for combustion gases. Lower front wall 26 is provided with an orifice 28 for mounting a fan assisted oil fired burner (not shown) which fires into combustion chamber 30 at the lower portion of the boiler .

IE 07 0 60 5 Located above the combustion chamber is a series of baffle plates 40, 41, 42 and 43 whose function is to impede the passage of combustion and flue gases from the combustion chamber 30. Each of the baffle plates is supported on fins 50 transversely extending into the boiler region. Each of the fins 50 is an elongate strip of metal welded to the inner surface 18 of the boiler so as to achieve good thermal transfer. In this particular embodiment the fins are 5mm thick steel plates and 30mm wide but these dimensions can be varied.

The bottom baffle plate 40 has a V shaped formation 45 which is used to deflect the fire ball produced by the burner. In this embodiment it is 5mm thick and the upper baffles 41, 42, 43 are manufactured from 3mm thick steel plates. A slot 46 is formed at each side of the baffle plate 40 so that the flue gases can escape at the sides of the baffle plate 40 adjacent the side walls 12 and 16 of the boiler thereby giving good heat transfer. Each of the baffles plates 41, 42 and 43 is provided with four support legs 60, one at each corner and a spacing tab 62 at the back of each plate. When installed, the legs 60 stand on the respective fins 50 thus creating a gap at the side of each baffle plate so that the combustion gases can travel around each fin 50. The passage of the combustion gases is indicated by the flow paths A and B as shown in Figure 2. Flue gases also flow at the back of the baffle plates 41, 42 and 43. The passage of flue gases is then kept close to the inner walls of the sidewalls of the boiler and assists in the heat transfer. In this embodiment, the legs 60 are 15mm high and the gap from the legs 60 to the inner surface 18 of the side walls is approximately 12mm. These dimensions may of course be varied to suit requirements as can the vertical distance between each fin which in the current embodiment is 40mm.

In the operation of the boiler, the combustion gases travel upwards. The gases firstly come in contact with the lower baffle 40 and divert outwards in three directions to the left, rear and right to contact the vertical water filled surfaces of the sidewalls. In order for the gases to travel upwards, they must come in contact with the fins 60 and are then diverted inwards into open space below the baffle plates. To exit from this area, the gases escape between the gap formed at the IE 07 0 60 3 sides of each baffle plate and scrub off the fins 60 and so on until the gases finally leave the boiler.

The continuous vertical movement of the combustion gases reduces the 5 combustion pressure in the boiler, thus requiring a lower pressure fan of approximately 1.2 MBars instead of a 3MBars fan which is in common usage.

It will of course be understood that the present invention is not limited to the 10 specific details herein described, which are given by way of example only, and that various alterations and modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims (5)

CLAIMS:

1. A boiler for a fan assisted burner, the boiler being of generally rectangular construction having a base, a top plate, four sidewalls 5 extending between the base and the top plate, one or more of the side walls being of hollow construction so as to act as heat exchangers for water flowing through the hollow side walls, a plurality of fins being fixed to the inner surfaces of the side walls, one or more transverse baffle plates engaged with the fins, spacer means being provided between the 10 baffle plates and the fins so as to generate an elongate gap between the baffle plates and the two opposing side walls and the rearmost side wall, whereby combustion and flue gases emanating from the combustion chamber extend through said elongate gaps between the fins, baffle plates and side walls to provide heat transfer from the combustion and 15 flue gases to the water passageways.

2. A boiler for a fan assisted burner as claimed in Claim 1 in which the fins are welded to the side walls of the boiler so as to provide for good thermal transfer.

3. A boiler for a fan assisted burner as claimed in Claim 1 or Claim 2 in which the transverse baffle plate nearest the base is provided with a Vshaped formation which, in use of the boiler, deflects the fire ball produced by a burner installed in the boiler, and a slot is formed at each 25 side of the baffle plate so that the flue gases can escape at the sides of the baffle plate adjacent the side walls of the boiler.

4. A boiler for a fan assisted burner as claimed in any one of the preceding claims, in which the spacer means provided between the baffle plates 30 and the fins comprises four support legs on each baffle plate and a spacing tab at the back edge of each baffle plate.

5. A boiler for a fan assisted burner substantially as herein described with reference to and as shown in the accompanying drawings.