GB2155609A

GB2155609A - Heat exchanger; space heater

Info

Publication number: GB2155609A
Application number: GB08406278A
Authority: GB
Inventors: Walter William Pritchard
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-03-09
Filing date: 1984-03-09
Publication date: 1985-09-25
Also published as: GB8406278D0; GB2155609B

Abstract

A heat exchange apparatus (10) comprises at least one chamber (33) having a generally cylindrical inner configuration of large diameter, an inlet (43) provided by an opening or openings for the inlet of hot or colder fluid, in the curved surface (44) of the cylinder, the inlet opening (42), or collectively the inlet openings, extending parallel or generally parallel to the cylindrical axis of the chamber over a major portion of the length thereof, an outlet (45) provided by an opening or openings for the outlet of the fluid, in the curved surface (44) of the cylinder, the outlet opening (45) or openings being spaced from the inlet opening or openings around the curved surface (44) of the cylinder, the outlet opening (45) or collectively the outlet openings, extending parallel or generally parallel to the cylindrical axis of the chamber (33) over a major portion of the length thereof, baffle means (40) within the chamber (33) adjacent to the inlet (42) to constrain the incoming fluid to flow from the inlet to the outlet to contact with the internal wall (44) of the chamber (33) the colder or hot fluid respectively to which or from which it is desired to transfer heat, in use, flowing in contact with the external wall of the chamber (33). <IMAGE>

Description

SPECIFICATION Heat exchange apparatus This invention relates to a heat exchange apparatus for transferring heat from hot fluid to a colder fluid. At present, heat exchange apparatus comprise one or more passes of small diameter tubes to maximise the surface area in contact with the fluids, to convey either the hot fluid or the colder fluid, the colder fluid or hot fluid respectively contacting the external surface of each of the tubes and receiving or given heat thereto.

In use, particularly where the hot fluid is made up of hot gases produced by combustion of fuel, the small diameter tube or tubes require frequent cleaning out or they become clogged with soot and other deposits which are detrimental to the efficiency of the heat exchange apparatus. Further, as the tube or tubes become blocked, a not inconsiderable back pressure builds up in the apparatus to further reduce the efficiency of combustion.

It is an object of this invention to provide a new or improved heat exchanger which overcomes or reduces these problems.

According to one aspect of the invention, we provide a heat exchange apparatus comprising a chamber having a generally cylindrical inner configuration of large diameter (as herein defined), an inlet provided by an opening or openings for the inlet of hot or colder fluid, in the curved surface of the cylinder, the inlet opening, or collectively the inlet openings, extending parallel or generally parallel to the cylindrical axis of the chamber over a major portion of the length thereof, an outlet provided by an opening or openings for the outlet of the fluid, in the curved surface of the cylinder, the outlet opening or openings being spaced from the inlet opening or openings around the curved surface of the cylinder, the outlet opening, or collectively the outlet openings, extending parallel or generally parallel to the cylindrical axis of the chamber over a major portion of the length thereof, baffle means within the chamber adjacent to the inlet to constrain the incoming fluid to flow from the inlet to the outlet in contact with the internal wall of the chamber the colder or hot fluid respectively to which or from which it is desired to transfer heat, in use, flowing in contact with the external wall of the chamber.

By "large diameter" we mean a diameter of more than 30cm but preferably the diameter is more than 45cm. Of course, the exact diameter (and length) of the body will be determined in accordance with the required output of the heat exchange apparatus that is required.

It will be appreciated that because the ia- meter of the chamber is large, this requires less frequent cleaning out, as blockage problems which occur with conventional heat exchanger apparatus which utilise small diameter tubes are entirely overcome. Further, maintenance of the larger diameter chamber is relatively simple.

Preferably, a plurality of such chambers are provided in the heat exchange apparatus, the outlet of one chamber being connected with the inlet of another, the inlet of the first chamber in the fluid flow path being connected to the hot or colder fluid source, and the outlet of the final chamber in the fluid flow path being connected to a flue, duct or the like, for conveying the fluid away from the apparatus, e.g. in suitable applications for venting, or re-cycling.

The heat exchange apparatus in accordance with the invention is particularly suited to heating colder fluid, such as air or water, in which case the inlet of the or the first chamber in the fluid flow path may be connected with a combustion chamber, and the outlet of the or the final chamber in the fluid flow path being connected to a flue.

Preferably the combustion chamber is also of generally cylindrical configuration having an outlet in the curved surface thereof provided by an opening or openings, the outlet opening or collectively the outlet openings extending along a major length thereof and being connected with the inlet of the or the first chamber of the heat exchange apparatus.

A fuel burner may be mounted at one end of the combustion chamber to direct a flame along the chamber. Because the outlet of the combustion chamber extends along a major portion of the length thereof, heat produced by the burning gases will pass into substantially the entire length of the or the first chamber of the heat exchange apparatus.

The burner is preferably of a pressure jet type which injects oil or gas fuel under pressure into the combustion chamber.

Preferably the colder fluid contacts not only the external surface of the chamber or chambers of the heat exchange apparatus, but also the external surface of the combustion chamber to add to the efficiency of heat transfer.

Because the opening in the combustion chamber extends along substantially the whole length thereof, the flame may extend into the or the first chamber of the heat exchange apparatus. In this case, the flame would impinge upon the baffle therein and thus the baffle may be made of a flame resistant material such as stainless steel.

Preferably the chamber or chambers of the heat exchange apparatus is/are located above the combustion chamber so that the hot gases produced in the combustion chamber pass upwardly into the heat exchange apparatus.

Where the heat exchange apparatus is provided with more than one chamber, preferably these are arranged vertically above one another so that the hot gases pass upwardly from one chamber into the next. In this ar rangement, the inlet of the or each chamber may be provided at the lowest position, and the outlet at the uppermost position, except for the first chamber in the fluid flow path, where the outlet may be provided at any convenient position.

Preferably, the heat exchange apparatus and combustion chamber is contained within an enclosure, the colder fluid to be heated passing in a passage between the enclosure and the external surfaces of the combustion and heat exchange chambers.

In a preferred embodiment, the heat exchange apparatus is used in a warm air heater, in which case the enclosure may have means to draw air into the enclosure and hence into contact with the external walls of the or each chamber of the heat exchange apparatus, and the combustion chamber where provided, and to pass the thus heated air from the enclosure.

The end or ends of the or each heat exchanger chamber may be openable to provide access to the chamber(s) for maintenance purposes.

In a preferred embodiment, a flame stabilising device is provided within the combustion chamber to ensure that the flame produced by the oil or gas pressure burner does not lift from the burner and thus lead to inefficient heating.

The flame stabilising device may comprise a cup-shaped mamber having a generally circular base and curved side wall extending therefrom, the device being located along the chamber generally opposite to the burner with the side wall thereof extending from the base towards the burner, the flame in use, impinging upon the flame stabilising device and thus being retained in position on the burner. Such a device not only prevents the flame from lifting from the burner, but where made from an appropriate material such as stainless steel which can glow red hot, waste products produced by the combustion of the fuel are purged and cleaned to give cleaner burning as well as a better flame pattern.

The side wall may extend from the base generally perpendicular thereto, or may be splayed outwardly depending on the flame characteristic required.

Preferably the position of the flame stabilising devie longitudinally of the combustion chamber is adjustable. This is advantages where it is required to change the output of the burner, for example to change the nozzle to up-rate or de-rate the burner, so that whichever new flame is produced, the flame stabilising device may be movable to accommodate that flame and prevent its lifting from the burner.

In a typical heat exchange apparatus in accordance with the invention, the combustion chamber and heat exchange chambers are between five and six foot long (1.52, to 1 ;83m); the fuel produces a temperature in the combustion chamber of about 1 500 C, and the temperature of the flue products after heat has been obtained therefrom in the heat exchange apparatus is about 600"C.

It will be appreciated that the invention thus provides an efficient heat exchange apparatus which overcomes the disadvantages of conventional heat exchange apparatus.

According to a second aspect of the invention, we provide a combustion chamber of generally cylindrical configuration with a fluid fuel burner being mounted at one end thereof, and a flame stabilising device comprising a generally cup-shaped member having a generally circular base and a curved side wall extending therefrom, the flame stabilising device being positioned along the combustion chamber generally opposite to the burner, with the side walls extending from the base towards the burner, the longitudinal position of the flame stabilising device being adjustable.

In one arrangement, the device may be adjustable by virtue of the chamber being provided with a plurality of brackets or other support members to any one of which the device may selectively be secured.

It is envisaged that where the burner is of the type in which the quantity of fuel burned thereby can be varied, the longitudinal position of the flame stabilising device may be adjusted automatically in response to a change of output of the burner.

The combustion chamber may comprise an outlet connected with the inlet of heat exchange apparatus in accordance with the first aspect of the invention.

The invention will now be described with the aid of the accompanying drawings, in which: Figure 1 is a perspective diagrammatic view of a heat exchange apparatus in accordance with the invention; and Figure 2 is a diagrammatic view through a combustion chamber for use with the heat exchanger according to the invention.

Referring first to Fig. 1, a heat exchange apparatus 10 is shown. The apparatus comprises an enclosure 11 having side walls 1 2a and 1 2b and end walls 1 3a and 1 3b, although the side wall 1 2a and end wall 1 3a have been shown transparent so as to reveal internal features of the apparatus.

The enclosure 11 has a base plate 1 5 mounted within, which extends between the side walls 1 2a and 1 2b and the end walls 1 3a and 1 3b and divides the enclosure into a bottom section 16 and a top section 1 7. The base plate 1 5 has an opening 1 7 therein for the passage of colder air to be heated from the lower section 1 6 into the upper section 1 7 of the enclosure.

A fan 20 is mounted in the lower section 1 6 and draws air from outside the enclosure 11 through louvres, such as shown at 21, of the lower section and passes the air through a plinth 22 up through the opening 1 7 in the base plate 15.

In the upper section 1 7 of the enclosure, a combustion chamber 25 is supported above the base plate 1 5 by supports 26 at the sides of the chamber 25 (only one of which can be seen), and a closure plate 27 at the end of the chamber adjacent end wall 1 3b and a further support plate 28 mounted adjacent end wall 13a.

The combustion chamber 25 will be described hereinafter in more detail with reference to Fig. 2. However, the combustion chamber supports combustion of fuel fed into the chamber 25 through a burner 30 which extends through a closed end 28' of the combustion chamber 25 and through the wall 1 3a of the enclosure.

The combustion chamber 25 is generally cylindrical and has in the curved surface 31 thereof an opening 32 which extends along substantially the entire length of the combustion chamber 25. The opening permits hot combustion gases created in the combustion chamber 25 to pass upwardly out of the combustion chamber into a chamber 33 of a heat exchange apparatus, hereinafter described.

The combustion chamber 25 is secured to the heat exchanger chamber 33 through mating flanges 34 and 35 which contact one another, again along the length of the combustion chamber 25 and the heat exchange chamber 33.

The heat exchange chamber 33 is also generally cylindrical in configurtion and the end thereof adjacent end wall 1 3b is closed by a cap 34. In practice, the end of the tube 33 adjacent wall 1 3a would also be closed by a cap such as shown at 34, although this has been omitted in the drawings so as to reveal the features present inside the chamber 33.

It can be seen that within the chamber 33 a baffle 40 provided, the baffle being of partcylindrical configuration and being mounted on supports 41 adjacent an inlet opening 42 which is aligned with outlet opening 32 of the combustion chamber 25. Thus, the hot products of combustion pass from the combustion chamber upwardly through the opening 32 into the heat exchange chamber 33 through the inlet opening 42 and impinge upon the baffle 40. Because of the curved shape of the baffle 40, the hot gases are constrained to pass upwardly in contact with the internal curved surface of the chamber 33 towards the upper part of the chamber 33.

It can be seen that in the upper part of the chamber 33, a further opening 45 is provided which communicates with an opening 46 of a further heat exchange chamber 47 mounted above chamber 33. Again, the openings 45 and 46 extend along substantially the entire length of the chambers 33 and 47 and permit the hot gases to pass upwardly from chamber 33 into chamber 47.

The baffle 40 is preferably made of a material such as stainless steel. It will be appreciated that as the opening 32 extends along substantially the entire length of the combustion chamber, that flame can pass from the combustion chamber into chamber 33 and impine upon the baffle 40. As the baffle 40 is made of stainless steel, it can withstand temperatures produced by the flame without deterioration.

The end of chamber 47 adjacent end wall 1 3b is also closed by a closure cap 49 and again, in practice, the end of chamber 47 adjacent end wall 1 3a would also be closed by a closure cap although again this has been omitted for clarity.

Within the chamber 47 is a further baffle 50 which is again supported on supports 51 above, i.e. adjacent the opening 46 in the chamber 47 and the baffle 50 again constrains hot gases passing upwardly through opening 46 to flow around the inside curved surface of the chamber 47. The closure cap 49 has extending therefrom a flue 53 which can be connected to a duct and directed from the vicinity of the heat exchange apparatus 10 to any required location.

It will be appreciated that as the hot gases flow in contact with the curved walls 31 of the combustion chamber 25, 44 of the chamber 33 and 54 of the chamber 47, that the walls will become heated. The air which passes into the upper part 1 7 of the enclosure 11 is constrained to flow in contact with the curved walls by virtue of fins 55 which extend from the side walls 1 2a and 1 2b (these are not shown extending from wall 1 2a again for clarity) so that the air which passes upwardly into the upper part of chamber 1 7 through the opening becomes heated.The air then passes from the enclosure through diffusers 60 which extend from the upper part 1 7 of the enclosure and the hot air is delivered into the environment surrounding the heat exchange apparatus.

Thus the apparatus described may be used for heating air in for example factory situation.

It will be appreciated that if it was required to use the heat exchange apparatus 10 to heat air at a location remote from its intended use, instead of diffusers 60 ducts or the likemay be connected to the enclosure 11 to duct heated air from the enclosure to the required location.

Various modifications may be made without departing from the scope of the invention. For example, the enclosure 11 need not be of the configuration shown, i.e. the chambers 25, 33 and 47 may be much shorter and/or larger in cross-section, and/or indeed longer and smaller in diameter. Preferably however, the diameters of the chambers 33 and 47 of the heat exchange apparatus are more than 30cm and more preferably more than 45cm.

The principle shown may be used to heat mediums other than air. In this event, water or another medium may flow in contact with the external walls of the chambers 25, 33 and 47 and thus become heated.

The heat exchange chambers 33 and 47 could be used for cooling rather than heating where for example the air or other fluid passing in contact with the external surface thereof, is hot than air passing in contact with the interior surfaces of the curved walls.

If desired, only one heat exchange chamber, or more than two may be provided. The openings for the inlet and outlet of fluid need not be provided as shown but could comprise a series of openings which collectively extend along a major portion of the length of the chamber or chambers. Further, the intlet need not be provided opposite the outlet as shown but may be merely spaced therefrom around the curved surface. Other forms of baffle may be used.

Referring now to Fig. 2, one example of a combustion chamber 25, such as may be used with the apparatus 10 of Fig. 1 as shown, although this combustion chamber has applications other than with such a heat exchange apparatus.

The burner 30 which may comprise an oil or gas burner, delivers a mixture of fluid fuel, fed thereto via feed pipe 60, and air, fed thereto through feed pipe 61, into the combustion chamber 25. The flame thus produced is shown at F, and this flame projects from the nozzle N of the burner along the chamber.

Where the pressure of the fuel/air mixture is insufficient, the flame F may not extend to the opposite end 62 thereof in which case, the flame may, in use, lift from the burner 30 and thus provide unsatisfactory combustion and an unsatisfactory flame pattern. This can result in hot spots on the end 62 damaging the combustion chamber. Accordingly, a flame stabilising device 70 is used to overcome this problem. The device 70 comprises a cup-shaped element 71 having a base 72 from which extends a curved side wall 73, the base 72 being circular.

As shown in firm lines, the side wall 73 extends from the base 72 generally perpendicularly although may extend at other angles such as shown in dotted lines, where a different flame characteristic is required. The element 71 is preferably made of stainless steel or other metal which can withstand the hot temperatures attained.

It has been found that the device 70 prevents the flame F from lifting from the burner where the device is correctly positioned. As shown, the device is correctly positioned at the tip of the flame F produced by the burner.

The hot gases thus produced can pass from the combustion chamber, for example, upwardly through opening 32 therein into a heat exchange apparatus above or may be ducted from the combustion chamber for use in any other way.

If it is required to exchange the nozzle N for a different nozzle to up-rate or de-rate the burner 30, it will be appreciated that the length of the flame projected into the combustion chamber will change. Accordingly, the position of the flame stabilising device 70 is adjustable. The cup-shaped element 72 is mounted on a support 73 which is receivable in any one of a selected number of slots 75.

Four slots are shown, although of course more than four or less than four may be provided as required.

In an alternative embodiment, burner 30 is of the type in which, in use, the quantity fuel that is delivered is changeable to up-rate or de-rate the burner to provide different outputs as required. In this event the position of the flame stabilising device 70 may be adjustable along a track by an actuator in response to control mechanism in dependence upon the output of the burner 30 and hence the length of the flame.

Any alternative means for adjusting the position of the flame stabilising device may be provided.

Claims

1. A heat exchange apparatus comprising a chamber having a generally cylindrical inner configuration of large diameter (as herein defined), an inlet provided by an opening or openings for the inlet of a hot or colder fluid, in the curved surface of the cylinder, the inlet opening, or collectively the inlet openings, extending parallel or generaly parallel to the cylindrical axis of the chamber over a major portion of the length thereof, an outlet provided by an opening or openings for the outlet of the fluid, in the curved surface of the cylinder, the outlet opening or openings being spaced from the inlet opening or openings around the curved surface of the cylinder, the outlet opening, or collectively the outlet openings, extending parallel or generaly parallel to the cylindrical axis of the chamber over a major portion of the length thereof, baffle means within the chamber adjacent to the inlet to constrain the incoming fluid to flow from the inlet to the outlet in contact with the internal wall of the chamber, the colder or hot fluid respectively to which or from which it is desired to transfer heat, in use, flowing in contact with the external wall of the chamber.

2. A heat exchange apparatus according to Claim 1 wherein the diameter of the chamber is more than 45 cm.

3. A heat exchange apparatus according to Claim 1 or Claim 2 wherein a plurality of chambers are provided in the heat exchange apparatus, the outlet of one chamber being connected with the inlet of another, the inlet of the first chamber in the fluid flow path being connected to the hot or colder fluid source, and the outlet of the final chamber in the fluid flow path being connected to a flue or duct, for conveying the fluid away from the apparatus.

4. A heat exchange apparatus according to any one of the preceding claims wherein the inlet of the or the first chamber in the fluid flow path is connected with a combustion chamber, and the outlet of the or the final chamber in the fluid flow path is connected to a flue.

5. A heat exchange apparatus according to Claim 4 wherein the combustion chamber is of generally cylindrical configuration having an outlet in the curved surface thereof provided by an opening or openings, the outlet opening or collectively the outlet openings extending along a major length thereof and being connected with the inlet of the or the first chamber of the heat exchange apparatus.

6. A heat exchange apparatus according to Claim 5 wherein a fuel burner is mounted at one end of the combustion chamber to direct a flame along the chamber.

7. A heat exchange apparatus according to Claim 6 wherein the burner is of a pressure jet type which injects oil or gas fuel under pressure into the combustion chamber.

8. A heat exchange apparatus according to any one of Claims 4 to 7 wherein a colder fluid contacts the external surface of the chamber or chambers of the heat exchange apparatus, and the external surface of the combustion chamber.

9. A heat exchange apparatus to any one of Claims 1 to 8 wherein the baffle within the or the first chamber of the heat exchange apparatus is made of a flame resistant material.

10. A heat exchange apparatus according to any one of Claims 4 to 9 where appendant to Claim 4 wherein the chamber or each chamber of the heat exchange apparatus is located above the combustion chamber so that hot gases produced in the combustion chamber pass upwardly into the heat exchange apparatus.

11. A heat exchange according to Claim 10 wherein appendant to Claim 3 wherein said plurality of chambers are arranged vertically above one another so that the hot gases pass upwardly from one chamber into the next.

1 2. A heat exchange apparatus according to Claim 11 wherein the inlet of each chamber is provided at the lowest position, and the outlet at the uppermost position, except for the first chamber in the fluid flow path, where the outlet may be provided at any convenient position.

1 3. A heat exchange apparatus according to any one of the preceding claims wherein the heat exchange apparatus, and combustion chamber where provided, is contained within an enclosure, colder fluid to be heated passing in a passage between the enclosure and the external surfaces of the heat exchange chambers.

14. A heat exchange apparatus according to Claim 1 3 wherein the heat exchange appa ratus is used in a warm air heater, the enclosure having means to draw air into the enclosure and hence into contact with the external walls of the or each chamber of the heat exchange apparatus, and the combustion chamber where provided, and to pass the thus heated air from the enclosure.

1 5. A heat exchange apparatus according to any one of the preceding claims wherein the end or ends of the or each heat exchange chamber is/are openable to provide access to the chamber(s) for maintenance purposes.

1 6. A heat exchange apparatus according to any one of Claims 4 to 1 5 where appendant to Claim 4 wherein a flame stabilising device is provided within the combustion chamber to ensure that the flame produced by the oil or gas pressure burner does not lift from the burner and thus lead to inefficient heating.

1 7. A heat exchange apparatus according to Claim 1 6 wherein the flame stabilising device comprises a cup-shaped member having a generally circular base and curved side wall extending therefrom, the device being located along the chamber generally opposite to the burner with the side wall thereof extending from the base towards the burner, the flame, in use, impinging upon the flame stabilising device and thus being retained in position on the burner.

1 8. A heat exchange apparatus according to Claim 1 7 wherein the side wall extends from the base generally perpendicular thereto.

1 9. A heat exchange apparatus according to Claim 1 7 wherein the side wall is splayed outwardly from the base an amount depending on the flame characteristic required.

20. A heat exchange apparatus according to any one of Claims 1 6 to 1 9 wherein the position of the flame stabilising device longitudinally of the combustion chamber is adjustable.

21. A heat exchange apparatus according to any one of Claims 4 to 20 where appendant to Claim 4 wherein the combustion chamber and heat exchange chambers are between five and six foot long (1.52m to 1.83m), the fuel produces a temperature in the combustion chamber of about 1500 C, and the temperature of the flue products after heat has been obtained therefrom in the heat exchange apparatus is about 600"C.

22. A heat exchange apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

23. A combustion chamber of generally cylindrical configuration with a fluid fuel burner being mounted at one end thereof, and a flame stabilising device comprising a generally cup-shaped member having a generally circular base and a curved side wall extending therefrom, the flame stabilising device being positioned along the combustion chamber generally opposite to the burner, with the side walls extending from the base towards the burner, the longitudinal position of the flame stabilising device being adjustable.

24. A combustion chamber according to Claim 23 wherein the device is adjustable by virtue of the chamber being provided with a plurality of other support members to any one of which the device may selectively be secured.

25. A combustion chamber according to Claim 23 wherein the burner is of the type in which the quantity of fuel burner thereby can be varied, the longitudinal position of the flame stabilising device being adjusted automatically in response to a change of output of the burner.

26. A combustion chamber according to any one of Claims 23 to 25 wherein the combustion chamber comprises an outlet connected with the inlet of heat exchange apparatus in accordance with any one of Claims 1 to 22.

27. A combustion chamber substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

28. Any novel feature or combination of features disclosed herein and/or shown in the accompanying drawings.