IE20070128A1 - Improvements to boilers - Google Patents

Abstract

A condensing apparatus (100) fits on a water heating boiler (10) having a fan assisted fuel burner, and inlet and an outlet for the passage of water through heat exchanger passageways for the transfer of heat to the water. An exhaust flue port (24) at the upper end of the bolier conveys exhaust flue gases to an outside atmosphere through a flue pipe. The condensing apparatus (100) comprises a first manifold (110) for fitting to the exhaust flue port of the boiler, a second manifold (130) for fitting to an end of the flue pipe and a compact condensing heat exchanger (12) clampable between the first and second manifolds (110, 130). The condensing heat exchanger (120) is adapted to extract additional heat from the exhaust flue gases and transfer the additional heat to the water of a heating system. <Figure 7a>

Description

The present invention relates to improvements to boilers, in particular boilers used as heat exchangers in heating installations, such as oil fired boilers. The invention particularly relates to condenser boilers, i.e. oil fired boilers including a condensing unit which extracts additional heat from the combustion or flue gases as they exit an oil fired boiler.

In order to increase the efficiency of oil fired boilers, there are numerous boilers on 10 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.

Also, there are many types of condensing boilers on the market. Usually these are purpose built boilers which include a condensing unit and therefore are quite expensive. There is a need for a condensing unit which can be added if desired to a standard boiler during manufacture and can also be retrofitted to existing boilers to convert them into condensing boilers The present invention also provides a condensing apparatus for fitting to a water heating boiler having a fan assisted fuel burner, an inlet and an outlet for the passage of water through heat exchanger passageways for the transfer of heat to the water, and an exhaust flue port at the upper end of the boiler for conveying exhaust flue gases to an outside atmosphere through a flue pipe, the condensing apparatus comprising a first manifold for fitting to the exhaust flue port of the boiler, a second manifold for fitting to an end of the flue pipe and a compact condensing heat exchanger clampable between the first and second manifolds, whereby the condensing heat exchanger is adapted to extract additional heat from the exhaust flue gases and transfer the additional heat to the water of a heating system.

Advantageously, the condensing heat exchanger is removably mountable on the boiler by the use of swivel joints for connection of the apparatus to the water supply system, whereby the condensing heat exchanger can be readily removed for cleaning and maintenance.

The present invention provides a condensing apparatus having 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, a condensing apparatus and a boiler in which the fins are welded to the side walls of the boiler so as to provide for good thermal transfer.

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 condensing apparatus and a condensing boiler according to the invention. In the drawings; Figure 1 is a perspective view from the front and one side of a boiler; and illustrating the passage of combustion gases at one side of the boiler; 701 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 a condensing apparatus for mounting on the boiler; Figure 6 is an exploded perspective view from another side of the main components of the condensing apparatus; Figure 7 is a perspective view of the condensing apparatus mounted on the boiler; Figure 7a is a perspective view of a more enlarged scale of the area marked A in Figure 7; Figure 8 is a side view of the condensing apparatus mounted on the boiler to which a burner has been fitted on the front thereof; and Figure 9 is a plain view of the arrangement as shown in Figure 8.

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 is provided with an orifice 28 for mounting a fan assisted oil fired burner 60 (see ΙΕο 70 Figures 8 and 9) which fires into combustion chamber 30 at the lower portion of the boiler 10.

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 60. 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 to0?0l2g 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 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 combustion pressure in the boiler, thus requiring a lower pressure fan of approximately 0.8 MBars instead of a 3 MBars fan which is in common usage, although it can be in the range of 0.6 to 1.5 MBars approximately.

The condensing apparatus 100 shown in Figures 5 and 6, is fitted to the top of the boiler 10 to convert the boiler into a condensing boiler. The condensing apparatus 100 comprises three main components, a first manifold 110, a compact condensing heat exchanger 120 and a second manifold 130. The first manifold 110 is seated over the flue outlet port so that the combustion gases are directed out of the first manifold 110, into the heat exchanger 120 and onto the second manifold 130. Included in the second manifold 130 is an outlet port 132 to which the flue pipe (not shown) is connected. Separate gaskets (not shown) are provided between the manifolds 110 and 130 and the heat exchanger 120. The entire assembly is clamped together by elongate bolts (not shown) which extend between the holes 112 in the first manifold 110 and the holes 134 in the second manifold 130. The water inlet and outlet for the condensing heat exchanger 120 is provided through the inlet and outlet pipes 122 and 124. These are connected into the water heating system using swivel joints (not shown) which are used to readily connect and disconnect the heat exchange into the system. In this way, the heat exchanger can be readily removed for cleaning and maintenance by undoing the manifold clamping screws and the swivel joints. Although the pipes 122 and 124 are shown extending from the upper surface of the heat exchanger 120, they can also extend from the sides. The heat exchanger as shown is a plate heat exchanger but any other known compact heat exchanger can be used. The ,E°7O128 manifolds 110 and 130 and the heat exchanger 120 are all manufactured from mild steel and stainless steel.

Referring now to Figures 7, 7a, 8 and 9, the condensing apparatus 100 is shown 5 fitted to the burner 10 so that the exhaust gases from the boiler rise up through the boiler and enter the apparatus 100 through the first manifold 110. As shown in Figure 8 the top plate 22 is also a water filled panel which collects the condensation from the heat exchanger 120. The heat exchange return water from this panel 22 is returned to the bottom of the boiler by means of channels 50.

Also a fan assisted burner 60 is attached to the front of the boiler 10.

As well as being fitted to the boiler 10, the condensing apparatus can be retrofitted to existing boilers in situ. Different shaped manifolds 110 and 130 would be required depending on the configuration of the boiler type being converted to function as a condensing boiler.

It will of course be understood that the present invention is not limited to the 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 (7)

CLAIMS:

1. A condensing apparatus for fitting to a water heating boiler having a fan assisted fuel burner, an inlet and an outlet for the passage of water through heat exchanger passageways for the transfer of heat to the water, and an exhaust flue port at the upper end of the boiler for conveying exhaust flue gases to an outside atmosphere through a flue pipe, the condensing apparatus comprising a first manifold for fitting to the exhaust flue port of the boiler, a second manifold for fitting to an end of the flue pipe and a compact condensing heat exchanger removably mounted between the first and second manifolds, whereby the condensing heat exchanger is adapted to extract additional heat from the exhaust flue gases and transfer the additional heat to the water of a heating system.

2. A condensing apparatus as claimed in Claim 1, in which the condensing heat exchanger is removably mountable on the boiler by the use of swivel joints for connection of the apparatus to the water supply system, whereby the condensing heat exchanger can be readily removed for cleaning and maintenance.

3. A condensing apparatus as claimed in Claim 1 or Claim 2 fitted to a boiler having 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 fixed to the inner surfaces of the side walls, one or more transverse baffle plates engaged with the fins, spacer means 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.

4. A condensing apparatus and a boiler as claimed in Claim 3 in which the fins are welded to the side walls of the boiler so as to provide for good thermal transfer.

5. 5. A condensing apparatus and a boiler as claimed in Claim 3 or Claim 4 in which the burner is operated at a pressure in the range of 0.6 to 1.5 Mbars and preferably 0.8 Mbars.

6. A condensing apparatus fitted to a boiler substantially as herein described

7. 10 with reference to and as shown in the accompanying drawings.