GB2310711A

GB2310711A - Baffle for boiler

Info

Publication number: GB2310711A
Application number: GB9604436A
Authority: GB
Inventors: Hedley Roland Mickleburgh
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-03-01
Filing date: 1996-03-01
Publication date: 1997-09-03
Anticipated expiration: 2016-03-01
Also published as: GB2310711B; GB9604436D0

Abstract

An oil or gas fired boiler baffle that may optionally be removed in use from the boiler has each of its peripheral edges provided with a succession of cut outs 1, 2, 3, so sized and spaced as to enable the gases to turbulate through them when the baffle is in use. A succession of baffles may have their cut-outs offset and the baffles may be connected together.

Description

IMPROVEMENTS IN AND REIA'flNG TO BOILERS Field of the Invention The invention relates to improvements in the design of boiler baffles fitted inside a heat exchanger of a boiler and to an improved boiler incorporating such a baffle.

Prior Art Known to the Applicant Typical water heating boilers particularly oil or gas fired boilers consist of a burner that directs hot combustion gases into the combustion chamber of the heat exchanger.

The combustion chamber is defined as that portion of the heat exchanger directly below the first baffle which is situated and suitably supported above the burner.

The internal walls of the heat exchanger typically encompass a plurality of baffles, the purpose of these baffles is to maximize the time spent by the gases within the confines of the heat exchanger. The baffles do this by increasing the total distance that the hot combustion gases have to travel before they can escape the confines of the heat exchanger. Furthermore, the positioning of the baffles ensure that turbulence is created which ensures that the maximum amount of heat can be exchanged between the heat exchanger and its surroundings.

Typically, the heat exchanger is surrounded by a water filled jacket and the water is heated by radiation and convection of heat generated by the combustion gases.

The now cooled combustion gases then escape through an outlet provided at or near the opposite end of the exchanger, known generally as a flue.

For further clarification, the reader is directed to Figure 1. In this illustration, the baffles are positioned generally horizontally across the combustion chamber cavity when the boiler is in its normal in use vertical position. However, such baffles can be positioned at any angle as specified by the combustion chamber designer. Along at least one edge of the baffle is a gap called the baffle gap through which, the combustion gases pass on their way to the output flue. In conventional baffle systems, the baffle gap needs to be small in order to optimise the heat exchange in this region. The intention is to extract as much heat as possible from the gases and hence they need to be directed into close contact with the combustion chamber walls for as long as possible to facilitate this. However, the small baffle gaps increase the combustion chamber pressure (CCP) and generally increase the resistance of the heat exchanger to the flow of the gases from the burner, resulting in noisy operation, particularly when starting up the boiler. This is obviously a problem in, for example, domestic boilers, where the market is constantly demanding more and more compact, discrete and quiet boilers. In addition, the marketplace is always demanding more efficient and cheaper boilers.

One of the most expensive components in any conventional heat exchanger if the baffles are not of a simple flat plate construction, are likely to be the baffles themselves. Baffles incorporating "skirted" sides or those that incorporate multiple protuberances, for example tabs of various shapes placed at various angles to the baffle (to create turbulence) are known.

Both of these types of baffle increase the efficiency of the heat exchange process that occurs and do so whilst still maintaining a relatively large baffle gap resulting in "silent" start up and operation. Nevertheless, from an engineering point of view, the production of such baffles involves a number of manufacturing steps which inevitably result in an increase in the overall cost of the finished boiler system. As most boiler manufacturers work to very tight profit margins, these increased manufacturing costs are inevitably passed on to the consumer.

Therefore, the production of a baffle that comprises a substantially flat plate (which can be punched" out of sheet metal on mass) that has the same or similar efficiency in terms of heat exchange as the more expensive baffles and which also reduces operational noise particularly when starting up the boiler, is a highly sought after commodity.

A conventional flat plate baffle covers substantially the cross sectional area of the heat exchanger except for the baffle gap which runs substantially the entire width of one side of the baffle.

Such a baffle system may cause such high combustion chamber pressure that any decrease in draft (negative pressure), at the combustion gas outlet from the heat exchanger can cause the static pressure against which the combustion air fan can operate efficiently to be exceeded. This may result in noisy and unreliable operation. Furthermore, any attempt to increase the size of the baffle gap to reduce the combustion chamber pressure results in a drop in efficiency.

It is an objective of the present invention to provide a baffle system that is cheap to engineer, is as efficient as "skirted" or protuberance incorporating baffles and that reduces the baffle gap whilst maintaining an acceptable combustion chamber pressure.

Summarv of the Invention According to a first aspect of the present invention, in its broadest sense, there is provided an oil or gas fired boiler baffle that may optionally be removed in use from the boiler characterised in that each of the peripheral edges of the baffle is provided with a succession of cut outs so sized and spaced as to enable the gases to turbulate through them when the baffle is in use.

Preferably, at least some of the opposing cut outs are at least partially out of phase with each other.

Preferably, the baffle is substantially flat.

Preferably, the baffle is substantially rectangular in shape.

Preferably, corresponding sides of opposing cut outs are substantially in phase with each other.

Preferably, at least two of the baffle plates are secured to each other via a securing means.

This aspect of the invention includes within its scope a boiler baffle substantially as herein described with reference to and as illustrated by any appropriate selection or combination of Figures 2 and 3 of the accompanying drawings.

Preferably, this aspect of the invention further includes within its scope a gas or oil fired domestic boiler incorporating a baffle in accordance with any of the arrangements specified above.

According to a second aspect of the invention, there is provided an oil or gas fired boiler provided with fixing means to accommodate a plurality of baffles in accordance with any of the arrangements specified above characterised in that the fixing means incorporated into the boiler will only allow baffles to be fitted into the boiler in a particular configuration.

Brief Description of the Drawings Figure 1 illustrates a typical heat exchanger and the accepted terminology of its various key components.

Figure 2 illustrates a top view of a baffle according to one embodiment of the invention.

Figure 3 shows a cross sectional top view of a baffle in place in a boiler according to one embodiment of the invention.

Description of the Preferred Embodiments The embodiment shown in Figure 2 represents currently the best way known to the applicant of putting the invention into practice. It is not the only way in which this could be achieved. It is illustrated and will now be described by way of example only.

Figure 2 illustrates an oil or gas fired boiler baffle seen from the top and generally referenced (1). The baffle is substantially flat and is substantially rectangular in overall shape.

Each peripheral edge of the baffle is provided with a succession of cut outs (2, 3, 4) that are so sized and spaced as to enable the hot combustion gases to turbulate through them when the baffle is in use (infra-Figure 3).

In the example illustrated in Figure 2, all of the opposing cut outs on the two longest sides of the baffle are completely out of phase with each other (3).

Whereas the opposing cut outs on the shortest sides of the baffle are completely in phase with each other (2). Furthermore, in Figure 2, the size and shape of each respective cut out is substantially the same and there is a sharp discontinuity between each respective end of each respective cut out (one end being illustrated by the numeral 6) and the beginning of each respective end (6) of each respective ridge (4).

Ridges (4) and cut outs (5) in this particular example meet other ridges and cut outs at (7) and (8) respectively. The longest side of each respective ridge and cut out at (7) and (8) respectively are both the same, which, is a result of two opposing sets of cut outs (one pair of which is illustrated as (3)) being completely out of phase with each other; everything else (i.e size of cut outs and dimensions of baffle) being the same. The baffle illustrated in Figure 2 is made of steel approximately 3mm thick and can be formed in a single action by "punching" out the baffle from a sheet of steel using an appropriately engineered dye and punching press.

Figure 3 illustrates a cross sectional view of baffle (1) in place in a boiler generally referenced (13) and again viewed from the top. The diagram shows the interior wall (9) of the heat exchanger surrounded by a jacket (11) the space in between being filled by water (10).

The hot combustion gases turbulate through each of the respective baffle gaps on all four sides of the baffle. The baffle gaps are generally referenced as (12), each respective one of which comprising three sides of a cut out (5) and one side of an interior wall of a heat exchanger (9).

The cross sectional area of the baffle (1) - taken from ridge to ridge, is substantially identical to the cross sectional area of the interior walls of the heat exchanger where the baffle resides. This ensures a close sliding fit between the baffle and the internal walls of the heat exchanger. In this particular illustration the baffle (1) is removable from the boiler (13) to enable rapid cleaning and servicing of the boiler/heat exchanger.

Furthermore, the boiler illustrated in Figure 3 is a domestic boiler and is provided with a plurality of support pins (not illustrated) that protrude inwardly along each internal wall, of the heat exchanger. These support pins support the baffle within the heat exchanger. The pins coincide with substantially the mid point of the longest side of each respective ridge (4).

In this particular example a series of baffles of the same general type as illustrated in Figure 2 are to be placed in the boiler (13) illustrated in Figure 3. Each respective baffle plate is spaced apart from each other baffle plate by fixed distances in parallel planes. This vertical "stacking" arrangement of baffle plates within the confines of the heat exchanger is so engineered by the placement of each respective plane of support pins that each respective baffle only fits into the heat exchanger in alternate configurations. In other words, the first plane of support pins substantially coincide with the mid point of the longest side of each respective ridge (4) enabling baffle (1) to be supported in place in Figure 3. The next plane of support pins will coincide with substantially the mid point of the longest side of each respective cut out as illustrated generally by the numeral 12 in Figure 3. This arrangement ensures that the next baffle to be inserted into this boiler (13) is rotated substantially through 180 , the axis of rotation being orthogonal to the plane of the baffle prior to insertion into the boiler (13). This continuing alternate arrangement of baffles ensures maximum turbulation of the hot combustion gases thereby increasing the efficiency of the heat exchanging process.

Furthermore, this arrangement of baffle gaps along each peripheral edge of the baffle plate means that each respective baffle gap (12) can have a much smaller cross sectional area resulting in more efficient heat exchange in this region with no increase in combustion chamber pressure. Furthermore in this particular arrangement there is an enhanced silencing effect in both start up and running of the boiler because there is no direct path for the combustion gases to follow.

This arrangement of support pins and sliding fit baffles also allow rapid servicing of boilers that are "top loaders" (i.e their access point is at the top of the boiler in its normal attitude of operation and "side" or "front" loaders.

The fact that the plates are of the sliding fit arrangement means that the side or front servicing panel can be hinged, or indeed more easily removed as it does not need to support a baffle.

In alternative embodiments not illustrated, the cut outs need not necessarily all be on the extreme edge of the baffle plate for example, only the cut outs (3) illustrated in Figure 2 that are out of phase along two edges of the baffle have to be on the extreme edge of the baffle plate. This arrangement ensures that no error can be made by the maintenance fitter/production line employee when it comes to replacing/fitting the baffle plates in the correct configuration. Furthermore, the cut outs need not necessarily be straight edged and having a sharp discontinuity between cut out (5) and ridge (4). It is envisaged that other embodiments of this aspect of the invention will have cut outs/ridges that are shaped differently. For example, the cut out need not necessarily have a well defined end or discontinuity (6) and the ridge likewise, need not necessarily have a well defined beginning or discontinuity (6).

In Figure 2, all of the opposing cut outs on the two longest sides of the baffle are completely out of phase with each other. In alternative embodiments, it is envisaged that only some of the opposing cut outs need necessarily be out of phase with each other. Furthermore, some of these opposing cut outs do not have to be completely out of phase with each other. The general shape of the baffle is dictated by the internal dimensions of the heat exchanger where the baffle(s) resides in use. The general shape of the baffle as illustrated in Figure 2 (1) is rectangular. Nevertheless, the principle of a baffle having a succession of cut outs along each of the peripheral edges can be applied to any heat exchanger by producing such a baffle that is designed to fit it. The ways and means of producing such a baffle are known to those skilled in the art.

The baffle (1) is made of steel. However, any heat resistant material that can withstand the rigours of use as a baffle can in principle, be used. It is therefore envisaged that in other embodiments, the baffle can be made from metallic or heat resistant material or combinations of both. The types of heat resistant material can be selected without further invention thought by the intended skilled addressee of this specification.

In the example illustrated in Figure 3, the support pins are to be found on each internal wall of the heat exchanger and are to be found supporting each respective ridge (4) of each respective baffle. In alternative embodiments, such support pins need not necessarily be on each and every internal wall of the heat exchanger nor do they have to provide support for each and every ridge (4) of the baffle.

Other means of securing each respective baffle in place are known to and these alternatives can be used.

The baffle described and illustrated in Figures 2 and 3 can be used for boilers that are both top loaders and side (front) loaders. The removal of such baffles from a front loader is relatively straightforward. However, removing them individually from a top loader requires either very dextrous fingers or a device capable of manipulating each respective baffle into a position such that it can be removed from the heat exchanger. Such a device would typically be a screwdriver inserted into the baffle gap and twisted. However, alternative embodiments not illustrated will allow the removal of baffles without the need of any removing device. It is envisaged that a "ring" centrally located and secured to the baffle could be used with the aid of a finger to remove the baffle. Other devices of this type can be envisaged without any further inventive thought.

To aid the insertion/removal of the baffle plates, an alternative embodiment not illustrated, could be envisaged where each respective baffle plate is welded or otherwise secured to a strip or tube of metal that is, for example, substantially orthogonal to the plane of each respective baffle plate.

In yet a further alternative embodiment not illustrated, this system of connecting all of the baffle plates together via a strip or tube of metal to form a single insertible/removable baffle system could apply to just two baffles connected together by a strip or tube of steel.

Claims

1. An oil or gas fired boiler baffle that may optionally be removed in use from the boiler characterised in that each of the peripheral edges of the baffle is provided with a succession of cut outs so sized and spaced as to enable the gases to turbulate through them when the baffle is in use.

2. A boiler baffle as claimed in Claim 1 characterised in that at least some of the opposing cut outs are at least partially out of phase with each other.

3. A boiler baffle as claimed in either Claim 1 or Claim characterised in that the baffle is substantially flat.

4. A boiler baffle as claimed in any of the preceding claims characterised in that the baffle is substantially rectangular in shape.

5. A boiler baffle as claimed in any of the preceding claims characterised in that the corresponding sides of opposing cut outs are substantially in phase with each other.

6. A boiler baffle as claimed in any of the preceding claims characterised in that at least two of the baffle plates are secured to each other via a securing means.

7. A boiler baffle substantially as herein described with reference to and as illustrated by any appropriate selection or combination of Figures 2 and 3 of the accompanying drawings.

8. An oil or gas fired boiler provided with fixing means to accommodate a plurality of baffles in accordance with any of the preceding claims characterised in that the fixing means incorporated into the boiler will only allow baffles to be fitted into the boiler in a particular configuration.

8. A gas or oil fired domestic boiler incorporating a baffle as claimed in any of the preceding claims.

9. An oil or gas fired boiler provided with fixing means to accommodate a plurality of baffles in accordance with any of the preceding claims characterised in that the fixing means incorporated into the boiler will only allow baffles to be fitted into the boiler in a particular configuration.

Amendments to the claims have been filed as follows

1. An oil or gas fired boiler baffle that may optionally be removed in use from the boiler characterised in that each of the peripheral edges of the baffle is provided with a succession of cut outs so sized and spaced as to enable the gases to turbulate through them when the baffle is in use, at least some of the opposing cut outs being at least partially out of phase with each other.

2. A boiler baffle as claimed in Claim 1 characterised in that the baffle is substantially flat.

3. A boiler baffle as claimed in Claim 1 or Claim 2 characterised in that the baffle is substantially rectangular in shape.

4. A boiler baffle as claimed in any of the preceding claims characterised in that the corresponding sides of opposing cut outs are substantially in phase with each other.

5. A boiler baffle as claimed in any of the preceding claims characterised in that at least two of the baffle plates are secured to each other via a securing means.

6. A boiler baffle substantially as herein described with reference to and as illustrated by any appropriate selection or combination of Figures 2 and 3 of the accompanying drawings.

7. A gas or oil fired domestic boiler incorporating a baffle as claimed in any of the preceding claims.