GB2124322A

GB2124322A - Heat exchanger cleaner

Info

Publication number: GB2124322A
Application number: GB08318169A
Authority: GB
Inventors: William John Holden
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-07-20
Filing date: 1983-07-05
Publication date: 1984-02-15
Also published as: GB8318169D0; GB2124322B

Abstract

A heat exchanger (10) above a solid fuel boiler comprises a plurality of vertically disposed tubes (11) within each of which is an elongate member (e.g. a chain) which depends from a support (14) which can be driven, by a motor in order to cause the elongate member to scrape off or dislodge from the inner surfaces of the tubes any soot or other powdery deposits. The support, mounted on eccentric crank mountings, is moved by said motor in an orbital path in a horizontal axis. Each chain has its upper end connected to one end of a swivel device whose other end is connected to the support; this makes the cleaning pattern random. Each chain comprises turbulence creators to improve heat extraction from air/flue gases. <IMAGE>

Description

SPECIFICATION Heat exchanger cleaner This invention relates to a heat exchanger cleaner.

In boilers using solid fuel, even in pulverised form, there is inevitably deposition of gas-borne dust and other products of combustion, and cleaning these deposits off the surfaces concerned is a dirty and unpleasant job which ideally should be done weekly. If the boiler heat exchanger has vertically extending flues through which the products of combustion are intended to travel, cleaning is impossible.

The principal object of the present invention is to facilitate cleaning of the vertical heat exchanger of a solid fuel boiler.

According to a first aspect, therefore, the present invention consists in a solid fuel boiler having a heat exchanger which comprises vertically disposed tubes through which hot air and the products of combustion are intended to pass; elongate means inside and extending lengthways of each of said tubes; and drive means connected to all of said elongate means and operable to cause said elongate means to displace whatever loose deposits are on the surfaces of said tubes, Said drive means could be manually powered but it will be preferred for said drive means to include an electric motor.

Said drive means, however powered, may be connected to a support member to which corresponding ends of the several elongate means are attached. In a preferred embodiment, said support member is placed above the upper ends of said tubes and the several elongate means depend therefrom into and along said tubes.

A subsidiary object of the present invention is to impart a certain degree of turbulence to the hot air and flue gases as they pass along said tubes; it will be realised that said air/flue gases will not be caused to give up as much heat as possible if they are simply allowed to travel along a straight flowpath through said tubes.

In order to attain said subsidiary object, each of said several elongate means may be a chain which hangs downwardly from said support member through the respective one of said tubes, the interconnected links of said chain being such as to cause a degree of turbulence of the ascending air/flue gases such as will assist in the extraction of heat therefrom.

In a generally preferred form of said boiler, each chain is connected to said support member by means of a swivel device which enables the entire chain to rotate or move angularly about its own imaginary longitudinal axis.

The boiler according to the present invention and as hereinbefore described may include a pot type underfeed stoker, a rotatable conveyor screw driven to feed coal along a tube to a retort surmounted by tuyeres which are connected by way of a plenum chamber to forced-draught means which supply primary air to said retort, and a device by means of which secondary air is directed onto the fuel bed (which is supported by said retort) from above. Said device may take the form of or may be included in a so-called reflective arch; in one form, said reflective arch may be a hollow box having holes at or near its periphery so that air supplied to the interior of the box will be blown downwardly onto said fuel bed, at least a part of the underside of said hollow box being clad by refractory material which reflects heat downwardly onto the fuel bed, thereby improving combustion.

In accordance with another important but optional feature of the invention, some or all of said chains could be long enough to make contact with and thus to clean other parts of the boiler below the level of the lower ends of said tubes; such other parts may include the top of the reflective arch referred to in the preceding paragraph.

The drive means will preferably cause the elongate means to describe a circular orbit within the respective one of said tubes. Said orbital movement may be obtained by the use of appropriately placed cranks (eccentrics).

One embodiment, by way of example only, will now be described briefly with reference to the accompanying drawings in which there are various views of a solid fuel boiler which incorporates some of the features described and illustrated in published United Kingdom Patent Applications No. 2,093,960A and No.

2,093,585A to which reference can and should be made in order to clarify any points which may not be clear and which do not in themselves form part of the inventive concept underlying the present invention. In said drawings: Figure 1 is a vertical section through a solid fuel boiler according to the present invention, the section having been taken on the line I-I in Figure 2; Figure 2 is another vertical section through said boiler taken on the line Il-I I in Figure 3; Figure 3 is a horizontal section through said boiler taken on the line Ill-Ill in Figure 2; Figure 4 is a partial view, looking in the direction of the arrow A in Figure 2, of said boiler with both of its top covers removed; Figure 5 is a detail view of a chain connected to a support member;; Figure 6 is a detail view of a part of the drive to the support member; and Figures 7 and 8 illustrate two different views of a swivel device by means of which a chain is connected to said support member.

Referring to the drawings, there is illustrated a boiler 5 which includes a heat exchanger 10 having vertically arranged tubes 11 through which flue gases will pass from the fuel bed (whose position is indicated by the reference numeral 12) to the flue pipe connection 13. It will be seen that there are twenty-five tubes 11 in the particular embodiment illustrated and that a support member indicated generally by the reference numeral 14 is positioned above the upper ends of said tubes.The support member 14 is connected to an electric motor/gear box assembly 1 5 and is mounted on four eccentric crank devices 1 6 (one at each corner), the connection of said member to the motor being by way of a bracket 1 7 of which one end is fixed to the member 14 (for example, by welding) and of which the other end is engaged by a crank 18 which is driven through said gear box by said motor.

The support member 14 illustrated consists of strips of angle iron welded into a frame which is square in plan. Two sets of parallel rods 1 9 are connected in any desired and suitable manner (e.g. by welding) to the frame and are so arranged that the rods of one set cross those of the other set. A chain 20 is suspended from each crossing point of the sets of rods 1 9, thereby providing twenty-five chains in the illustrated embodiment, and it will be seen from the drawings that each crossing point is so placed (relatively to the respective tube 11 beneath the support member 14) that each chain 20 hangs down into a respective one of the tubes 11 and is in contact with the inside surface of said tube over the entire length of said tube.It has been discovered during use of the boiler that it is desirable to connect each chain 20 to the respective crossing point by means of a swivel device 50 (Figures 7 and 8) which is well-known in itself and which comprises two closed eyes or rings 51, 52 which are so interconnected at 53 as to be capable of rotation one relatively to the other.

When it is desired to clean the tubes 1 lithe motor 1 5 is energised in order to rotate the crank 1 8. Rotation of the crank 18 causes the entire support member to be moved on its eccentric crank devices 1 6 in a horizontal plane in an orbital path which is such that each chain 20 moves over the whole (or substantially the whole) of the inside surface of the respective tube 11, with consequent dislodgement of all of the fly ash and soot therefrom.

The boiler illustrated is provided, above the fuel bed 12, with a reflective arch 21 which comprises a hollow box 22 and a block 23 of refractory material attached to the underside of said box. The interior of the box 22 is connectible by a conduit 24 to a forced-draught means (not illustrated) and said draught is directed at the fuel bed 12 through a plurality of apertures 25 around the periphery of said box. The or some of the chains 20 may, if desired, be long enough to contact the upwardly directed surface 30 of the reflective arch and also possibly other surfaces of said arch or of the fire box.

The use of chains 20 as the tube cleaners is considered to be a particularly neat solution of the existing problem because said chains also act as a means for creating turbulence in what would otherwise be a straight-path flow of a hot fluid through the tube concerned. This turbulence enables more heat to be extracted from said hot fluid. It is thought that the very shape or configuration of a chain (whose successive links face in different directions as seen in Figure 7) will create the necessary degree of turbulence but, if need be, small deflecting plates or other devices (not illustrated) could be added along the length of the chain.Even without a swivel device 50, a chain will achieve a certain level of cleaning but it has been found that a precise and invariable pattern of cleaning is obtained and that said pattern does leave uncleaned portions of the inside surface of the tube concerned. The employment of a swivel device 50 to connect each chain 20 to its respective crossing point has been found to cause each chain to rotate or move angularly about its notional longitudinal axis in a perfectly free manner and randomly; this random rotation/angular movement has considerably improved the cleaning of the flue.

Another positive feature of the boiler according to the present invention is that the vibration, generated by the support member 14 as it is caused to describe its circular orbit and transmitted by said member to the heat exchanger and other parts by way of said eccentric crank devices 16, helps to loosen fly ash and soot.

It is stated above that the drive means will preferably cause the elongate means to describe a circular orbit within the respective one of said tubes. Of course, as an alternative to such movement, said drive means could rotate each elongate means; such rotation, about the notional longitudinal axis of said elongate means, would cause at least part thereof to become subject to centrifugal force, and this would give a good cleaning action.

It is to be understood that the boiler 5 shown in the accompanying drawings has an underfeed pot type stoker, a retort surmounted by tuyeres which are connected to forced-draught means, and a conveyor means by which fuel (e.g. coal) is fed to the retort. Only some of said features are illustrated herein in order to keep the drawings simple, the others being known per se from said published Applications.

Claims

1. A solid fuel boiler having a heat exchanger which comprises vertically disposed tubes through which hot air and the products of combustion are intended to pass; elongate means inside and extending lengthways of each of said tubes; and drive means connected to all of said elongate means and operable to cause said elongate means to displace whatever loose deposits are on the surfaces of said tubes.

2. A boiler as claimed in Claim 1, wherein said drive means includes an electric motor.

3. A boiler as claimed in Claim 1 or Claim 2, wherein said drive means is connected to a support member to which corresponding ends of the several elongate means are attached.

4. A boiler as claimed in Claim 3, wherein said support member is placed above the upper ends of said tubes and the several elongate means depend therefrom into and along said tubes.

5. A boiler as claimed in any one of the preceding Claims, wherein each of said several elongate means is a chain which hangs downwardly from said support member through a respective one of said tubes, the interconnected links of said chain being such as to cause a degree of turbulence of the passing air/flue gases as will assist in the extraction of heat therefrom.

6. A boiler as claimed in any one of the preceding Claims, including a pot type underfeed stoker, a rotatable conveyor screw driven to feed coal along a tube to a retort surmounted by tuyeres which are connected by way of a plenum chamber to forced-draught means which supply primary air to said retort, and a device by means of which secondary air is directed onto the fuel bed (which is supported by said retort) from above.

7. A boiler as claimed in Claim 6, wherein said device takes the form of or is included in a socalled reflective arch, at least some of said chains being long enough to make contact with and thus to clean at least the top of the reflective arch.

8. A boiler as claimed in Claim 3 or in any Claim which is appended to Claim 3, wherein said drive means, when activated, causes each elongate means to describe a circular orbit within the respective one of said tubes.

9. A boiler as claimed in Claim 8, wherein said orbital movement is obtained by the use of cranks (eccentrics) in said drive means and in the mounting(s) of said support member.

10. A boiler as claimed in Claim 3 or in Claim 4 or in any of Claims 5 to 7 when appended to Claim 3 or in Claim 8 or in Claim 9, wherein the connection between the support member and each of said corresponding ends of the several elongate means is by a swivel device.

11. A solid fuel boiler constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

12. Any features of novelty, taken singly or in combination of the embodiments of the invention hereinbefore described with reference to the accompanying drawings.