GB2140903A - Furnace - Google Patents

Abstract

A furnace (1) has a primary air intake pipe (7) opening to the outside in the top of the furnace and extending to the fire chamber (10) with a slope relative to a vertical axial plane of the fire chamber, the pipe having its free end (8) located at a short distance from the combustion grid (3) so as to cause a primary air current to be sucked through a load of fuel in the furnace and evacuate the smoke of combustion through an outlet (4). <IMAGE>

Description

SPECIFICATION Furnace This invention relates to a furnace, for example for use as a domestic heating appliance or as a boilerfor producing a hot fluid such as water for domestic plumbing or central heating.

The object of the invention is to promote combustion of a bulky fuel load in a furnace so as to be able to make use of fuels consisting of crude materials which have not been cut up or packaged, for example bulky logs of wood, briquettes, large bundles of paper, with an optimum yield.

According to the invention, there is provided a furnace comprising a fire chamber, a combustion grid, an outlet for combustion products, and at least one primary air intake pipe opening to the outside in the top of the furnace and extending into the fire chamber with a slope relative to a vertical axial plane of the fire chamber, said pipe having its free end located at a short distance from the combustion grid so as to cause a primary air current to be sucked through a load of fuel in the furnace in use and sweep the combustion products towards the outlet.

Preferably, at least one sealable opening is also provided in the top of the furnace for introducing secondary air into the fire chamber.

The advantages of a furnace according to the invention are that, at least in preferred embodiments, it ensures complete and intense combustion of the fuel with the optimum calorific yield for reduced fuel and maintenance costs.

Some embodiments of the invention will now be explained by way of example and with reference to the accompanying drawings in which: Figure 1 is a vertical section through a first embodiment of a furnace according to the invention; Figure 2 is a top plan view of the furnace of Figure 1 with the lid taken off; Figures 3 and 4 show an alternative embodiment of the furnace shown in Figures 1 and 2; Figure 5 is a vertical section through a furnace and boiler according to a further embodiment of the invention; Figure 6 is a top plan view of the boiler in Figure 5, with the jacket partially cut away; and Figure 7 is a vertical section on the line A-A in Figure 5.

Reference is made first to Figures 1 and 2 which show a first embodiment. The furnace 1 has a loading port 2 which can be closed off by a cover (not shown), a combustion grid 3 and a smoke outlet 4. In its upper partthefurnace 1 has an opening for the introduction of primary air provided with an adjustable sealing valve 6. The opening 5 gives access to a primary air intake pipe 7 which extends into the fire-chamber 10 sloping at a certain angle relative to a vertical axial plane and this pipe extends so that its free end 8 is located at a small distance from the combustion grid 3. The free end of the primary air intake pipe 7 is surrounded by a protective sleeve 9. It is also possible to provide a plurality of primary air intake pipes like the pipe 7.

The direct intake of primary air into the fire chamber through the pipe 7 produces a circulation of air current through the load of fuel which is being burnt in the fire chamber 10 as indicated by the arrows, thus causing intense and total combustion of the fuel and ensuring an optimum calorific yield.

This arrangement makes it possible to use bulky logs or briquettes as the fuel without any need to cut them up. It is also possible to burn large unprepared bundles of paper to provide intense long-term heating. The furnace according to the invention thus make it possible to achieve continuous heating with a relatively cheap crude fuel. The combustion and hence the heat can be adjusted by means of the valve 6. A secondary air intake opening is provided in the top of the furnace, likewise provided with a valve 11 as shown in Figure 2, in orderto perfectthe adjustment of combustion.

An advantage of the furnace is that it ensures effective continuous heating which leaves only a small quantity of ash residue which need only be emptied after long periods of heating, thus considerably reducing the maintenance required: it has been shown experimentally that only two orthree emptyings per winter are sufficient during continuous heating.

Moreover, owing to the circulation of primary air current sucked in through the load of fuel, the combustion smoke is evacuated continuously without any blowback problems.

The furnace is completed by an ash-pit 12 below the combustion grid 3, with a small gate or drawer 13. Advantageously, the body of the furnace is surrounded by a protective jacket consisting of a mesh, for example.

The furnace may be produced in a variety of embodiments. An alternative embodiment of the furnace in Figure 1 is shown in Figures 3 and 4, which are views corresponding to those in Figures 1 and 2. In this alternative embodiment, the smoke outlet 4 opens into the upper wall instead of being in the side wall as in the embodiment shown in Figures 1 and 2.

Figures 5 to 7 illustrate another embodiment in which a furnace according to the invention acts as the heating element of a boiler. In these drawings, the same reference numerals have been used as in Figure 1 to designate identical or equivalent elements. The fire chamber 10 in this case is provided with four primary air intake pipes 7. The side walls and upper wall ofthefire chamber 10 form a sleeve which constitutes part of a reservoir 20 for a liquid to be heated, such as water. The reservoir 20 has a fluid inlet 21 at the bottom and a fluid outlet 22 at the top.

The heat of combustion in the fire chamber 10 heats the fluid in the reservoir 20 and the outlet 22 therefore releases the hot fluid. The smoke outlet 4 opens into a smoke box 23 having a smoke escape 24. The smoke box 23 contains a heat recovery or exchange means 25 diverting some of the fluid from the reservoir 20 through the smoke box 23 so that the heat of the smoke evacuated also serves to heat a quantity of fluid, thus increasing the yield of the boiler.

The furnace may be described as a "turbocombustion" furnace.

Claims (6)

1. A furnace comprising a fire chamber, a combustion grid, an outlet for combustion products, and at least one primary air intake pipe opening to the outside in the top of the furnace and extending into the fire chamber with a slope relative to a vertical axial plane of the fire chamber, said pipe having its free end located at a short distance from the combustion grid so as to cause a primary air current to be sucked through a load of fuel in the furnace in use and to sweep the combustion products towards the outlet.

2. A furnace as claimed in claim 1, wherein the free end of the or each primary air intake pipe is surrounded by a protective sleeve.

3. A furnace as claimed in claim 1 or 2, further comprising at least one sealable opening in the top of the furnace for the introduction of secondary air into the fire chamber.

4. A furnace as claimed in claim 1,2 or 3 further comprising an ash-pit below the combustion grid.

5. Afurnace as claimed in any one ofthe preceding claims, wherein the walls of the fire chamber are arranged so as to form part of a fluid reservoir having a fluid inlet at the bottom and a fluid outlet at the top, and the outlet for combustion products opens into a box containing heat exchange means which diverts fluid from the reservoir towards the fluid outlet.

6. Afurnace substantially as hereinbefore described with reference to Figures 1 and 2; or 3 and 4; or 5,6 and 7, of the accompanying drawings.