GB2195009A

GB2195009A - Boilers

Info

Publication number: GB2195009A
Application number: GB08611465A
Authority: GB
Inventors: Herbert Edward Boulter
Original assignee: BOULTER BOILERS Ltd
Current assignee: BOULTER BOILERS Ltd
Priority date: 1986-05-10
Filing date: 1986-05-10
Publication date: 1988-03-23
Also published as: GB2195009B; GB8611465D0

Abstract

A combustion chamber baffle system in a boiler includes a first section comprising a tube 13 closed by a ceramic plate 14 and means 18 for spacedly mounting the tube within the combustion chamber and a second section 19 is spacedly mounted downstream of the first section which comprises a plate 20 having a cross section larger than the cross section of the tube and being substantially the same as the cross section of the combustion chamber. A peripheral flange or flanges 21 extends about the periphery of the first plate in a direction towards the tube, the plate including a central hole 22 to allow gases to escape to be fed towards the flue outlet. Combustion gases from a burner 5 passing into the combustion chamber in which the baffle system is mounted describe a path which extends towards the ceramic plate 14 and changes direction and moves in the opposite direction to escape the tube, then passes along the outer edge of the tube, hits the plate 20 and is entrained along the plate of the second section towards the central hole 22 through which the gases pass towards the flue outlet 10. <IMAGE>

Description

SPECIFICATION Improvements in and relating to boilers Field of the Invention The invention relates to an improved baffle system for the combustion chamber of a boiler, and to an improved boiler incorporating such a baffle system.

Baffle systems are frequently used in boiler combustion chambers in an attempt to dissipate the heat in the combustion gases so that the combustion gases are cooled down before being fed to the flue outlet of the boiler.

The invention can be applied to many different types of gas or oil fired boilers but is applicable with particular advantage to the type of boiler which emits combustion gases from a burner and fires the gases sideways into and through a combustion chamber which then are passed upwards and out through an output flue. An example of such a boiler is the one sold under the trade mark CAMRAY 50/70 WH sold by Boulter Boilers Limited of Meteor Close, Norwich, Norfolk.

One baffle system which has been developed for such a boiler comprises a tube for placing within the combustion chamber such that its longitudinal axis lies parallel to the direction of flow of gases into the combustion chamber. The tube is typically cylindrical and has a cross-section which is smaller than the cross-section of the combustion chamber.

A ceramic plate mounted within the tube to close off the tube. The combustion gases are fired onto the plate and have to then change direction to work their way out of the front of the tube and along the outer edge of the tube towards the opposite end of the combustion chamber. The gases are then fed out towards the flue.

The aim of the present invention is to produce a baffle system which produces increased efficiency within the combustion chamber.

Summary of the Invention According to the invention there is provided a combustion chamber baffle system and a boiler incorporating such a baffle system, which system includes a first section comprising a tube, including a ceramic plate mounted within the tube to close off the inside of the tube, and means for mounting the tube within the combustion chamber such that gases are fired in a direction parallel to the longitudinal axis of the tube onto the ceramic plate, and such that a gap is defined between the combustion chamber and the tube which extends about the periphery of the tube, and a second section for mounting downstream of the first section which comprises a first plate having a cross section larger than the cross section of the tube and being substantially the same as the cross section of the combustion chamber, and with a peripheral flange or flanges extending about the periphery of the first plate and extending in a direction towards the tube, the plate including a hole at or about its centre to allow gases to escape to be fed towards the flue outlet, the second section being adapted to be mounted spaced apart from the first section with its central hole being located about the longitudinal axis of the tube with the plate lying substantially perpendicular to the longitudinal axis of the tube, such that combustion gases passing into a combustion chamber in which the baffle system is mounted describe a path which extends towards the ceramic plate and changes direction and moves in the opposite direction to escape the tube, then passes along the outer edge of the tube, hits the plate of the second section and is entrained along the plate of the second section towards the central hole through which the gases pass towards the flue outlet.

The path described by the gases through the baffle system creates a system in which a great deal of heat it dissipated.

The first section and the second section of the baffle system may be separate bodies but this can cause problems in mounting the sections in their correct relative positions within the combustion chamber. It is therefore preferred that the first and second sections are one integrai unit which are coupled together such that the spacing between the first and second section is predetermined and fixed.

In the case where the second section is attached to the first section the plate lifts the downstream end of the tube clear of the walls of the combustion chamber and therefore form part of the spacing means of the first section.

It is preferred that the spacing system for the upstream end of the tube is provided by a series of legs which extend from each face of the tube between the edge of the tube and the combustion chamber wall.

Preferably the tube has a square cross section with the plate of similar square or rectanguiar cross section.

In this case conveniently the legs may comprise L-shaped sections of metal with one part of the L being bolted onto the face of the tube with the perpendicular plate extending perpendicular to the tube wall to form a leg.

The means attaching the first section to the second section of the baffle system may typically comprise a member of U-shaped cross section where one half of the U may be coupled to the tube and the other bolted to the flange of the first plate.

It is preferred that the boiler includes a combustion chamber having a two pass system. This is a system in which the combustion chamber is split into two parts lying parallel to one another. Gases are fed into the first part and feed along the first part of the first direction to the opposite end of the chamber and are then passed directly to the second part and pass along the second part in an opposite direction to which it passed through the first part and then exits from the boiler. The first and second part of the combustion chamber are typically separated by a baffle.

It is further preferred that the boiler in this case is a two pass system in which the direction of flow of the gases is substantially horizontal such that a burner sits directly adjacent the combustion chamber and feeds the gases sideways into the combustion chamber along the first part of the combustion chamber up into the second part of the combustion chamber, along the second chamber and upwards into the flue.

Preferably the baffle system in accordance with the invention is situated in the first part of the combustion chamber. More preferably a second baffle system is mounted within the second part of the combustion chamber to provide even greater efficiency within the combustion chamber. Preferably the second baffle system consists of a plate having projections projecting from each face of the plate and arranged such that the projections cross the direction of flow of the gases within the second part of the chamber. Preferably the projections do not extend the full width of the plate and are arranged in a pattern to create turbulence of the gases as they pass through the baffle system. The fact that the projections project from both faces of the plate serves to space the central plate from the walls of the second part of the combustion chamber.

Both sets of baffles may be made in stainless steel. At least the area surrounding the ceramic plate against which the burner fires must be made of stainless steel as this takes the worst of the impact from the hot combustion gases. The remainder of the baffles may be made of lower grade steel or of aluminium plate.

The preferred features of the invention help provide a boiler with an increased efficiency.

For example the heat output of the boiler is increased from approximately 50,000 BTU to approximately 70,000 BTU in the boiler sold under the trade mark CAMRAY 50/70 WH.

Brief Description of the Drawings A baffle system for a boiler combustion chamber and the boiler combustion chamber in accordance with the invention will now be described, with reference to the accompanying drawings, in which: Figure 1- is a section through a combustion chamber- of a boiler; Figure 2 is a perspective view of the baffle system; Figure 3 is a schematic end elevation of the baffle system of Figure 2; Figure 4 is a schematic side elevation of the baffle system of Figure 2; Figure 5 is a section through a second baffle system for the second pass of the combustion chamber; and, Figure 6 is a plan view of the second baffle system of Figure 5.

Description of the Preferred Embodiment The boiler whose combustion chamber is shown in Figure 1 is a CAMRAY 50/70 WH Boiler sold by Boulter Boilers Limited of Meteor Close, Norwich, Norfolk. This combustion chamber 1 is generally cuboid in shape with dimensions approximately 445 millimeters by 365 millimeters by 289 millimeters.

The combustion chamber is a two-pass system having a first lower pass 2 and a second upper pass 3 parallel to the first pass 2. The first part 2 of the chamber is separated from the second part 3 of the chamber by baffle 4.

An oil fired burner 5 fires gases through a gas duct 6 through an openable door 7 into the first part 2 of the combustion chamber in a sideways direction towards the opposite end of the combustion chamber 1. At the opposite end of combustion chamber 1 is a ceramic plate 8 to protect the back of the combustion chamber 1. The baffle 4 does not extend to the back of the chamber 8 but a gap 9 of width 120 millimeters is defined to provide a space from which the gases can pass from the first part of the chamber 2 to the second part of the chamber 3. The gases then pass in a direction back towards the burner 5 until they pass to the flue outlet 10 to be eventually output into the atmosphere.

In order to increase the efficiency of the combustion chamber and dissipate the heat from the combustion gases a first baffle system is positioned in the first part of the chamber 2. A flange 11 depends from the extreme edge of the baffle 4 into the second part 2 to define a stop against which the baffle system is pushed when placing the baffle system within the chamber to define the limit position of the baffle system. The first baffle system is shown in more detail in Figures 2, 3 and 4.

The baffle system comprises a first section 12 which comprises a tube 13 which here is of square cross section which is less than the cross section of the second part of the combustion chamber. The tube 13 has mounted within it a ceramic plate 14 which serves to close off the tube 13. The ceramic plate 14 is positioned between a steel plate 15 which includes peripheral flanges 16 riveted to the inside of the tube and a flange 17 spaced from the plate 16 to hold the ceramic plate in place.

Eight legs 18 provide the means for mounting the tube 13 within the combustion chamber 1 such that a gap is defined between the combustion chamber and the tube. This gap can be seen in detail in Figure 1. The legs 18 consist of L-shaped brackets riveted to the outer faces of the tube such that there are two legs 18 attached to each face arranged with one half of the L riveted to the tube with the other half perpendicular to the face of the tube to space the tube from the inner walls of the second part of the chamber 2. The baffle system includes a second section 19 which comprises a plate 20 of cross section larger than the cross section of the tube and substantially identical to the inner cross section of the second part of the combustion chamber with flanges 21 extending from the periphery of the plate 20 towards the tube 13.At the centre of the plate 20 is a hole 22 which is cylindrical with a diameter of 90 millimeters.

The second section 14 is permanently attached to the first section 12 in a position spaced apart from the first section and down-stream of the ceramic plate 14 and such that the hole 22 lies about the longitudinal axis 23 of the tube. In this case the longitudinal axis 23 of the tube and the central axis 24 of the hole coincide.

The means attaching the first section 12 to the second section 19 comprises four brackets 25 of U-shaped cross section which are elongate and extend from the first section 12 to the second section 19. The width of the Ushaped cross section 25 is arranged such that one side of the U-shape 26 can be riveted to the outer edge of the tube 13 whilst the other side 27 of the U-shaped cross section can be bolted to the flange 21 of the plate. This provides a firm attachment for the two sections of the baffle system without affecting unduly the flow of gas about the baffle system. The baffle system also includes elongate section 28 riveted to the front of the first section 12 to provide a handle for removal of the baffle system and positioning of the baffle system within the combustion chamber 2.

The position of the baffle system is shown in detail in Figure 1 which shows that the baffle system is arranged such that the axis of the tube 13 is arranged generally parallel to the direction of infeed of the gases such that the gases are fed against the ceramic plate 16. The flow of gases is shown in detail in the Figure. The gases are passed from the burner 5 towards the ceramic plate 16 and they change direction and go outside the tube and run along the outer edge of the tube 13 until the gas hits plate 20 which causes the gases to be entrained towards hole 22 through which the gases pass before passing upwards through gap 9 towards the second pass of the chamber.

Within the second chamber 3 is situated a second baffle system 29 which is shown in detail in Figures 5 and 6. The baffle system 29 comprises a rectangular plate 30 having depending therefrom a series of projections 31 in the form of flanges which lie transverse to the flow of gases through the chamber.

None of the flanges 31 extend across the whole width of the plate 30 and their pattern of arrangement is shown in Figure 6. This pattern ensures that turbulence is created within the gases as they pass through the chamber. For convenience each projection 31 consists of an L-shaped section of metal riveted to the plate. The front of the plate 30 is riveted to the handle 32 with peripheral flange 33 to define a stop position when mounting the baffle system within the chamber. The baffle system 29 is fed along the second part of the chamber 3 until the flange 33 bears against the corner of baffle 4 to define the correct working position of the second baffle system 29. The working position of second baffle system 29 is where the last flange 34 is aligned with the flue outlet 10.

In this example the first baffle system in the first part of the combustion chamber is made of stainless steel and the second baffle system 29 is made of aluminium plate.

The boiler incorporating these two baffle systems can now give a heat output of approximately 70,000 BTU.

Claims

1. A combustion chamber baffle system and a boiler incorporating such a baffle system, which system includes a first section comprising a tube, including a ceramic plate mounted within the tube to close off the inside of the tube, and means for mounting the tube within the combustion chamber such that gases are fired in a direction parallel to the longitudinal axis of the tube onto the ceramic plate, and such that a gap is defined between the combustion chamber and the tube which extends about the periphery of the tube, and a second section for mounting downstream of the first section which comprises a first plate having a cross section larger than the cross section of the tube and being substantially the same as the cross section of the combustion chamber, and with a peripheral flange or flanges extending about the periphery of the first plate and extending in a direction towards the tube, the plate including a hole at or about its centre to allow gases to escape to be fed towards the flue outlet, the second section being adapted to be mounted spaced apart from the first section with its central hole being located about the longitudinal axis of the tube with the plate lying substantially perpendicular to the longitudinal axis of the tube, such that combustion gases passing into a combustion chamber in which the baifle system is mounted describe a path which extends towards the ceramic plate and changes direction and moves in the oppisite direction to escape the tube, then passes along the outer edge of the tube, hits the plate of the second section and is entrained along the plate of the second section towards the central hole through which the gases pass towards the flue outlet.

2. A system according to Claim 1 and a boiler incorporating such a system in which system the first and second sections are one integral unit which are coupled together such that the spacing between the first and second section is predetermined and fixed.

3. A system according to Claim 1 or Claim 2 and a boiler incorporating such a system in which system the spacing system for the upstream end of the tube is provided by a series of legs which extend from each face of the tube between the edge of the tube and the combustion chamber wall.

4. A system according to any of the preceding Claims, and a boiler incorporating such a system, in which system the tube has a square cross section with the plate of similar square or rectangular cross section.

5. A boiler incorporating a baffle system according to any of the preceding Claims which boiler includes a combustion chamber having a two pass system.

6. A boiler according to Claim 5 and which is a two pass system in which the direction of flow of the gases is substantially horizontal such that a burner sits directly adjacent the combustion chamber and feeds the gases si deways into the combustion chamber along the first part of the combustion chamber up -into the second part of the combustion cham ber, along the second chamber and upwards into the flue.

7. a boiler according to Claim 5 or Claim 6 in which the baffle system is situated in the first part of the combustion chamber.

8. A boiler according to Claim 5, Claim 6 or Claim 7 in which a second baffle system is mounted within the second part of the com bustion chamber.

9. A boiler according to Claim 5 in which the second baffle system consists of a plate having projections projecting from each face of the plate and arranged such that the projections cross the direction of flow of the gases within the second part of the chamber.

10. A boiler according to Claim 9 in which the projections do not extend the full width of the plate and are arranged in a pattern to create turbulence of the gases as they pass through the baffle system.

11. A boiler incorporating a combustion chamber baffle system substantially as de scribed with reference to and as illustrated in the accompanying drawings.