GB2187271A - A vertical boiler - Google Patents

Abstract

A vertical boiler 1 has a heat transfer enclosure formed by water carrying side walls 2, front wall and rear wall 4. An gas duct 25 is formed against the side and front walls of an upper chamber of the boiler. The duct 25 is defined by a channel shaped retaining plate 31 which engages against a plurality of vertical fins 32 projecting from the side walls 2 and the front wall 3 to divide the duct 25 into a plurality of smaller vertically extending ducts. To promote heat transfer a flow restricting zig-zag shaped baffle 33 is located in each smaller duct. The baffles 33 are a rattle fit in the ducts 30 and are removable, as is the plate 31, for cleaning. An upper baffle plate 42 extends across the top of the upper chamber 20 to direct hot combustion gases downwardly to the enter the gas duct 25 at its lower end. <IMAGE>

Description

SPECIFICATION A vertical boiler The present invention relates to boilers and more particularly but not exclusively to oil and gas fired boilers of the type often referred to as, vertical enclosed or free-standing boilers.

Generally speaking, vertical boilers have a heat transfer enclosure formed from a side wall at least some of which is hollow for reception of water, the said enclosure defining a lower combustion chamber and an upper chamber communicating with a gas outlet flue.

The side wall of the enclosure may in fact be formed from separate interconnected walls forming a hot water jacket. The boiler is usually rectangular in cross-section.

The major problem with such boilers is to ensure that the heat transfer surfaces which are arranged for contact with the hot flue gases of combustion transfer the heat efficiently to the water contained within the heat transfer wall with minimum soot deposits.

This means therefore, that the heat transfer surfaces and the arrangement of the flow of the combustion gases within the boiler must be correctly arranged so as to ensure an adequate heat exchange between the flowing combustion gases and the liquid surrounding the gas passageway. One of the major problems that arises is that the heat transfer surfaces often become coated with soot and other deposits depending on the type of fuel used. Accordingly, the heat transfer surfaces must be regularly cleaned. Unless very elaborate methods of cleaning of the accumulated soot are provided it is necessary to have removable panels or other means of access to the boiler for cleaning it.

The present invention is directed towards providing an improved construction of vertical boiler which will have sufficient thermal efficiency and at the same time will be easily cleaned than conventional vertical boilers.

According to the invention there is provided a vertical boiler having a heat transfer enclosure formed from a side wall at least some of which is hollow for carrying water, the enclosure defining a lower combustion chamber and an upper chamber communicating with a gas outlet flue wherein an inner duct is formed against at least portion of the side wall of the upper chamber to direct hot combustion gases from the combustion chamber against the heat conducting surfaces of the sidewall.

Preferably the gases are directed through the duct from a lower combustion gas inlet to an upper discharge outlet to an exhaust gas flue.

In a particularly preferred embodiment of the invention the duct is formed by a retaining plate spaced-apart from the side wall.

Preferably the retaining plate abuts a plurality of substantially vertically arranged heat exchanger fins projecting from the side wall to form a plurality of substantially vertically extending smaller ducts.

In one embodiment of the invention each smaller duct includes a flow restrictor. Typically the flow restrictor comprises a baffle.

In a particularly preferred embodiment of the invention the baffle comprises a plate member bent back and forth to form a zig-zag configuration, the plate alternately contacting or projecting adjacent the side wall and retaining plate.

Preferably each flow restrictor is a loose or rattle fit in its corresponding duct.

In one embodiment of the invention an upper baffle plate extends substantially across the upper chamber to divert the flue gases entering the upper chamber to the lower combustion gas inlet to the duct.

Preferably the restrictors are removable for cleaning.

In a preferred embodiment of the invention the retaining plate is removable for cleaning.

The invention will be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a cut-away perspective view from the front of a boiler according to the invention; Fig. 2 is a cut-away perspective view of the boiler from the rear; Fig. 3 is a typical vertical side section through the boiler; and Fig. 4 is a plan view of the boiler with a lid removed.

Referring to the drawings there is illustrated a vertical boiler indicated generally by the reference numeral 1 having a heat transfer enclosure formed by a side wall which in this case comprises a pair of side walls 2, a front wall 3 and a rear wall 4. There is further a base 5 and a removable top cover 6 mounted on studs 7 and incorporating a conventional seal 8 of asbestos rope. A gas exit flue 10 is mounted by means of a plate 9 on the rear wall 4. The walls 2, 3 and 4 are hollow water jackets of conventional construction and are connected to a water heating system by an inlet pipe 11 and an outlet pipe 12. A door 15 incorporating a hole 16 for a burner, not shown, is mounted on the front wall 3 and further incorporates a viewing flap 17.

The interior of the boiler 1 is divided into an upper chamber 20 and a lower combustion chamber 21. An inner gas duct indicated generally by the reference numeral 25 is formed against the side walls 2 and the front wall 3 of the upper chamber 20 and has a lower flue gas inlet 26 in the combustion chamber 21 and an exit 27 adjacent the top of the boiler and below the cover 6. The inner gas duct 25 comprises a plurality of separate smaller ducts 30 formed by a channel-shaped retaining plate 31 abutting against a plurality of substantially vertically arranged heat exchanger fins 32 projecting from the front wall 3 and side walls 2.Each duct 30 incorporates a flow restrictor formed by a removable baffle 33 which is formed from a plate bent back and forth on itself to a zig-zag shape to alternately contact or project adjacent the walls 2 or front wall 3 of the upper chamber and the retaining plate 31. Each baffle 33 is a loose or rattle fit in the smaller gas duct 30 for ease of removal and to promote combustion gas flow through the ducts 30. Each baffle 33 is formed into a hook 34 at its upper end so that they may be suspended from the retaining plate 31 as can be seen from the drawings. A number of hooks 34 may be connected together by a connector piece to allow a number of the baffles to be removed simultaneously. In turn the retaining plate 31 is removably mounted on the side walls 2 and front wall 3 by a plurality of support tabs 35.

The retaining plate 31 also includes a plurality of outwardly projecting lugs 36.

A removable upper baffle plate 42 having a handle 43 is mounted on the lugs 36. The baffle plate 42 is flush against the rear wall 4 and spaced-apart slightly from the retaining plate 31 adjacent the front wall 3.

In use, and referring particularly to Fig. 2 combustion gases shown by the arrows are driven into the combustion chamber 21 and against the walls 2, 3 and 4. The gases then travel up along the rear wall 4 and are directed downwardly by the top plate 42. The majority of the combustion gases are delivered to the lower inlet of the inner gas duct 25.

The hot flue gases rising through the inner gas duct 25 are delivered out the exit at 27 and across the upper chamber 20 to the flue 10. A small proportion of the exhaust gases which rise to the baffle plate 42 will exit where the upper baffle plate 42 is spacedapart from the retaining plate 31. Again these hot flue gases will exit through the flue 10.

The invention has certain major advantages.

Firstly, the use of the zig-zag baffle plates and the inner gas duct ensures that the majority of the flue gases come into contact with what are effectively the heat exchange surfaces of the boiler thus promoting adequate heat transfer between the hot flue gases and the transfer medium which is normally water. Further, the construction is such that on removal of the lid 6 the retaining plate and the zig-zag baffles may be lifted out of the boiler. It is also possible to lift out the upper baffle plate 42. Thus, it will be appreciated that the boiler is particularly suited for cleaning and further it will have a high thermal efficiency.

It will be appreciated that the boiler may be of any suitable horizontal cross section for example circular or rectangular.

It will also be appreciated that in some cases additional baffle plates may be provided to direct combustion gases for increased heat transfer efficiency. It is also envisaged that the baffle plates may be provided by water tanks.

Claims (12)

1. A vertical boiler having a heat transfer enclosure formed from a side wall at least some of which is hollow for carrying water, the enclosure defining a lower combustion chamber and an upper chamber communicating with a gas outlet flue wherein an inner duct is formed against at least portion of the side wall of the upper chamber to direct hot combustion gases from the combustion chamber against the heat conducting surfaces of the side wall.

2. A boiler as claimed in claim 1 in which the gases are directed through the duct from a lower combustion gas inlet to an upper discharge outlet to an exhaust gas flue.

3. A boiler as claimed in claim 1 or claim 2 in which the duct is formed by a retaining plate which is spaced-apart from the side wall.

4. A boiler as claimed in claim 3 in which the retaining plate abuts a plurality of substantially vertically arranged heat exchanger fins projecting from the side wall to form a plurality of substantially vertically extending smaller ducts.

5. A boiler as claimed in claim 4 in which each smaller duct includes a flow restrictor.

6. A boiler as claimed in claim 5 in which the flow restrictor comprises a baffle.

7. A boiler as claimed in claim 6 in which the baffle comprises a plate member bent back and forth to form a zig-zag configuration, the plate alternately contacting or projecting adjacent the side wall and retaining plate.

8. A boiler as claimed in any of claims 5 to 7 in which each flow restrictor is a loose or rattle fit in its corresponding duct.

9. A boiler as claimed in any of claims 2 to 8 in which an upper baffle plate extends substantially across the upper chamber to divert the flue gases entering the upper chamber to the lower combustion gas inlet to the duct.

10. A boiler as claimed in any of claims 5 to 9 in which the restrictors are removable for cleaning.

11. A boiler as claimed in any of claims 3 to 10 in which the retaining plate is removable for cleaning.

12. A boiler substantially as hereinbefore described with reference to the accompanying drawings.