GB2215035A - Improvements relating to stoves - Google Patents

Abstract

A stove designed to produce and withstand high operating temperatures, comprises a furnace chamber 14 which has a suspended restrictor plate 18 of metal or ceramics hooked into the chamber body so as to be removable. The plate partially closes rear which hinders the passage of combustion products and so heat is retained within the furnace chamber thus the operating temperature is increased. The furnace chamber is secured to a stove casing 12 at one location and supported by the stove casing at a second location so as to slide relative thereto and thus resist stresses due to thermal expansion. The stove has a flue or chimney which extends serpentine over the furnace chamber to increase the effective surface area of heat exchange between the gases of combustion and air from fan 32 as it flows over chamber 14 and flue tubes 40, 46 to cowl 36. The flue has an adjustable after burner air inlet tube (50, Fig. 2) which draws air into the flue to aid transport of the combustion gases through the flue. <IMAGE>

Description

Improvements Relating to Stoves This invention relates to stoves. and in particular concerns stoves for burning wood and other waste materials for the disposal of same.

A wood burning stove is known which comprises a burning chamber or furnace which is an elongated metallic body which in use lies substantially horizontally, and at the bottom of the chamber is a fire grate. The material to be burned is inserted into the chamber at one end. and the products of combustion emerge from the other end and pass into a vertical chimney or flue. A fan located to the underside of the chamber blows air over the exterior surface of the chamber, in order to heat the air, and the heated air is used for space heating purposes.

In order to provide for maximum combustion in the furnace chamber. the rear end of the chamber is partially closed by means of a throat or restrictor plate, which prevents the products of combustion passing too quickly to the chimney, whereby the heat is retained within the chamber which reaches a higher operating temperature and causes burning of at least some of the gaseous products of combustion before they can escape to the atmosphere. It is to be noted that for polution reasons. the gaseous products of combustion which are ejected into the atmosphere should be as deposit or smoke-free as possible.

Whilst the described apparatus operates to the extent that the gaseous products of combustion are reasonably smoke-free, the apparatus is virtually inoperable in that it is essentially of welded construction and the components thereof are subjected to large differential expansion effects with the result that the stove simply fractures in use.

The present invention aims at providing in a stove for burning waste wood and other waste material, a number of aspects which enhance the stoves operation.

In accordance with a first aspect of the invention. the furnace chamber of a stove is provided with a restrictor plate to restrict the escape of the gaseous products of combustion to a flue or chimney, said restrictor plate being removably suspended in relation to the chamber so that it requires no unfastening for the removal of same.

By such means, the restrictor plate can be readily removed for repair and replacement. Restrictor plates in such application do require replacement at intervals. Secondly, by such mounting of the restrictor plate severe stresses set up between the body of the chamber and the restrictor plate as occur in the conventional stove, are avoided.

The restrictor plate preferably is simply hooked on to hook mountings on the chamber body. The restrictor plate preferably is a plate of metal or ceramic material capable of withstanding the high temperatures which exist in wood burning stoves.

In another aspect of the invention, a stove comprises a furnace chamber which is surrounded by a stove casing.

The furnace chamber is secured to the stove casing at a first location, and at a second location is supported on the stove casing so as to slide relative thereto whereby stresses which might arise between the furnace chamber and casing due to thermal expansion, are avoided. Thus, if the furnace chamber body expands in length due to the high temperature therein, and the casing does not expand or does not expand to the same extent, the mountings on the furnace body where it is supported by a casing for sliding movement, will slide relative to the casing avoiding thermal expansion stresses.

The said mountings on the furnace body may simply comprise blocks which seat on support ledges of expansion brackets on the furnace casing.

In a third aspect of the invention. the chimney or flue is caused to serpentine back and forth over the top of the furnace chamber so that when air is blown over the furnace chamber from the underside thereof for the heating of the air, the air will also be passed over the lengths of flue which lie above the furnace body.

By this means there will be increased heating of the air and further extraction of the heat from the gaseous products of combustion before they are discharged into the atmosphere.

In yet a further aspect, the furnace chamber is located in a casing and where the products of combustion emerge from the furnace chamber into the flue or chimney, there is provided a breather tube to allow air to be drawn into the flue thereby enhancing the flue draft and achieving quicker transport of the products of combustion through the flue and into the atmosphere.

The breather tube may be provided with a restrictor which is adjustable to control the volume of air which is drawn in through the breather tube, as required.

Each aspect of the invention constitutes an improvement in burning stoves, but any two or more may be combined in a burning stove to provide inventive combinations, and in a machine embodying all aspects of the invention, particularly improved results are obtained.

In such a machine embodying all aspects of the invention4 the furnace chamber preferably is arranged so as to lie with its axis substantially horizontal.

The chamber may suitably be circular in cross section, and one end, the front end, is preferably welded to a casing which surrounds the chamber. The front end is the end through which the material to be burned is inserted, and such front end may be closable by means of a furnace gate or door. The said restrictor plate is located on hooks inside the furnace chamber and at the rear end thereof, such plate being in the shape of a major segment of a circle, the space between its straight edge and the inner surface of the chamber forming the outlet for the products of combustion.

Also at said rear end on its outer surface, the chamber is provided with sliding block supports. which rest on ledges of furnace expansion brackets on the inside of the casing.

The outlet from the furnace chamber emerges into a smoke box, and at the top of the smoke box first flue pipes extend parallel to the furnace chamber and over the top of same and extend to a return box at the front end of the furnace chamber. Second flue pipes extend from the return box to a flue stack or chimney at the rear end of the chamber and from which stack or chimney the gaseous products of combustion emerge into the atmosphere. In the flue box and adjacent the inlet of the first flue pipes is a breather tube enabling atmospheric air to be drawn into the products of combustion before they enter the first flue pipes.

Such breather tube is provided with an adjustable restrictor to control the amount of air which is drawn in through the tube during operation of the stove.

To the underside of the furnace chamber is a fan which is arranged to blow air drawn in from the atmosphere over the furnace chamber and over the first and second flue tubes in order to extract heat from the furnace chamber and from the products of combustion as they pass through the first and second flue tubes1 the casing being arranged to collect the heated air and discharge it back into the atmosphere for space heating purposes through a distributor cowl located at the top of the casing.

The operation of such a machine will be readily understood, but will be explained briefly in the following.

The waste material to be burned, in particular wood chippings is placed in the furnace chamber and ignited by any conventional method. The waste material burns in the furnace chamber1 and the products of combustion pass into the smoke box through said outlet, the restrictor plate functioning to maintain a high temperature in the furnace chamber to provide relatively clean products of combustion. The products of combustion pass through the first and second flue pipes before passing to the flue stack being discharged into the atmosphere, and air is drawn into the products of combustion through said breather tube in order to enhance the passage of products of combustion through the stove. At the same time. air is blown over the furnace chamber and the flue tubes in order to extract heat to provide hot air for space heating purposes.

A machine constructed to include the various aspects of the invention has performed over a test period extremely satisfactory, and such stove does not suffer from the thermal expansion problems encountered in the conventional wood burning stove. Efficient combustion has been achieved and the products of combustion are relatively smoke-free.

The accompanying diagrammatic drawings show an embodiment of the present invention which includes all of the inventive aspects, and in such drawings: Fig. 1 is a sectional side view of the stove according to the embodiment of the invention; and Fig. 2 is a sectional end view of the stove shown in Fig. 1.

Referring to the drawings, the stove 10 comprises an outer casing 12 made up of removable panels which may be of or include heat insulating material. The furnace chamber 14 is of circular cross section, and at a front end is provided with an aperture which can be closed by means of a furnace door 16. At the rear end, the chamber, is partially closed by means of the removable restrictor plate 18 as described herein, and the outlet from the furnace chamber under the plate 18 is indicated by reference 20.

As shown, the chamber 14 is provided with a fire grate 22, and an ash pan 24 serves to collect ash from the grate 22, the chamber iLl being cut away to allow ash to fall through the grate and into the pan 24. The ash pan has a door 26 which can be opened and closed at will, for example for the removal of the ash. Each of the doors 16 and 29 has a breather inlet closable by means of a breather flap 28, 30 closable to any desired degree. and inside the casing 12 is an air blowing fan 32 set with its outlet 34 arranged to cause a flow of air to pass up over the furnace chamber 14 so that the flowing air will be heated and the heated air can emerge from the distribution cowl 36 mounted at the top of the casing 12.

The products of combustion from the chamber 14 emerge from the outlet 20 into a smoke box 38, and from the smoke box 38 the products as shown pass through first return flue tubes 40, 42, which are arranged horizontally and in parallel arrangement, and the products of combustion emerge from the tubes 40, 42 into a return box 44. From the turn box LlLl4 the products of combustion enter and pass along a return fluid tube 46, and eventually they are discharged to atmosphere out of an exhaust gas flue or chimney all8.

The smoke box 38 is provided with an inlet aperture to which is connected an after burner air inlet 50 which acts ash breather tube, and an adjustable control 50 which is screw operated and serves to control the volume of air which can be drawn in through the tube 50 into the smoke box 38.

The drawings show only one embodiment of the invention, and which is substantially as hereinbefore described1 and it will be appreciated that modifications and variations may be made without departing from the scope of the invention or any of the inventive aspects.

Claims (10)

1. A stove for burning waste wood and other waste material comprising a furnace chamber provided with a restrictor plate to restrict the escape of gaseous products of combustion to a flue or chimney, said restrictor plate being removably suspended in relation to the chamber so that it requires no unfastening for removal of same.

2. A stove according to Claim 1 wherein the restrictor plate is hooked on to hook mountings on the chamber body.

3. A stove according to Claim 1 or 2, wherein the restrictor plate preferably is a plate of metal or ceramic material capable of withstanding high temperatures.

4. A stove comprising a furnace chamber which is surrounded by a stove casing.

5. A stove according to Claim 4, characterised in that the furnace chamber is secured to the stove casing at a first location, and at a second location is supported on the stove casing so as to slide relative thereto whereby stresses which might arise between the furnace chamber and casing due to thermal expansion are avoided.

6. A stove according to Claim 5, wherein the means for slidably supporting the furnace chamber comprises blocks which seat on support ledges of expansion brackets on the furnace casing.

7. A stove according to Claims 1 to 6, characterised by a chimney or flue which extends serpentine back and forth over the top of the furnace chamber such that the effective area of heat exchange between the hot gases contained therein and space air blown over the furnace chamber is increased.

8. A stove according to Claim 7, characterised by a means of drawing air into the flue comprising an after burner air inlet tube which enables the products of combustion to be quickly transported through the flue to the atmosphere.

9. A stove according to Claim 7, wherein the after burner air inlet tube is provided with a restrictor which is adjustable to control the volume of air which is drawn through the after burner air inlet tube.

10. A stove substantially as hereinbefore described with reference to the accompanying diagrams.