FR2516209A1 - Inverted-combustion hot water generator - has grille of refractory bricks above secondary combustion chamber over which hot gases pass - Google Patents

Abstract

The hot water generator has a combustion chamber (1) suspended above a secondary combustion chamber (13) which is refractory lined (13,23). The hot gases pass from the upper chamber through the secondary chamber and up to the flue (25) passing over a heat exchanger (26). The fuel grille (9) is lined with spaced firebricks (12) at the bottom of the combustion chamber. The secondary chamber door (17) is double skinned and acts as a secondary air register. Air enters through the lower, outer opening (21) and discharges into the furnace through the upper, inner opening (22).

Description

IMPROVEMENT IN REVERSE COMBUSTION HEATERS.

 The present invention relates to reverse combustion heaters. Such devices include an upper storage and distillation chamber into which wood logs are introduced through a closable upper opening.

A lower post-combustion compartment communicates with the upper storage and distillation chamber via a support grid on which the logs rest. The post-combustion compartment itself communicates with a gas evacuation pipe, and has a lower fresh air inlet. Such devices allow relatively efficient and complete combustion of the wood to be produced and are an improvement over non-reverse combustion fireplaces in which the discharge of gases is effected from above. However, the combustion of the gases produced by the distillation of wood logs in the distillation chamber is relatively incomplete, so that a non-negligible amount of carbon monoxide can be measured in the exhaust gases, and the vapors produced in the long term cause corrosion of the compartment afterburners and the heat exchangers which may be arranged there.

 The object of the present invention is in particular to propose a device making it possible to substantially improve the combustion of wood.

 Another object of the invention is to provide a device in which the corrosion of the post-combustion compartment and of the exchangers is significantly reduced.

 To do this, and according to a characteristic of the invention, the support grid constituting the base of the upper storage and distillation chamber comprises disjoint refractory bricks placed on angles. The refractory bricks heat up in contact with the combustion and the embers, and have a very hot surface which is licked by the gases produced by the distillation of the wood logs, causing the ignition of these gases and their complete combustion during their passage. in the post-combustion chamber. It has been observed that with such an arrangement, the combustion of the heating device is notably improved because the level of carbon monoxide detected in the gas evacuation pipes is greatly reduced compared to the devices of the prior art. in addition, the refractory bricks cause the almost complete elimination of the vapors produced by the distillation of the logs, so that the corrosion of the exchangers and of the post-combustion compartment is greatly reduced. The refractory bricks play both the log support roll, like the support grid of the devices of the prior art, and the role of re-igniter and catalyst to ignite the gases and the distillation vapors and complete the combustion.

 According to another characteristic of the invention, the post-combustion compartment is lined with refractory bricks. These bricks make it possible on the one hand to avoid corrosion of the walls of the post-combustion compartment, on the other hand to provide thermal insulation of these walls, and finally to complete the post-combustion of the gases.

 According to another characteristic of the invention, the post-combustion compartment has a lateral opening which can be closed by a door for the removal of the ashes; debt door has two metal walls separated by an intermediate compartment communicating with the outside of the heating device through a lower opening and with the interior of the post-combustion compartment through an upper opening. Thus, the post-combustion supply air enters through the lower opening, heats up in the intermediate compartment, and passes through the upper opening, so that the air entering the compartment is heated and does not cool. the refractory bricks lining the post-combustion compartment and forming the support grid. This improves the efficiency of refractory bricks to complete the combustion of wood.

 According to another characteristic of the invention, in the case of producing a boiler for the production of a hot liquid fluid, the heat exchanger is arranged in the gas evacuation pipe downstream of the afterburner compartment. In the devices of the prior art, the heat exchanger enters the post-combustion compartment, so that its corrosion is relatively rapid. According to the arrangement of the present invention, this heat exchanger is outside the post-combustion compartment, so as to avoid its corrosion.

 Other characteristics and advantages of the present invention will emerge from the following description of a particular embodiment, made in relation to the attached figures, among which - FIG. 1 represents a schematic side sectional view of the device according to the present invention ; and - Figure 2 shows a top sectional view of the same device.

 The embodiment shown in the figures relates to a reverse combustion boiler allowing the production of a hot liquid fluid. The boiler comprises a storage and distillation chamber 1 limited by an upper cover 2, side walls 3 and a bottom 4. The side wall 3 has a first opening 5 selectively closable by a door 6 for the introduction of wood logs in chamber 1, and a second lateral opening 7 for the admission of outside air. The bottom 4 has inclined ramps 8 connected by a support grid 9.

The support grid 9 comprises two transverse angles 10 and 11 on which are arranged transversely a row of disjoint refractory bricks 12.

 The chamber 1 communicates, by the support grid 9, with a lower post-combustion compartment 13 which limits at its upper part by the bottom 4 of the chamber i, at its lower part by the bottom 14 of the boiler, and comprising a side wall 15 provided with an opening 16 selectively closable by a door 17. The door 17 comprises an interior wall 18 and an exterior wall 19 of metal separated by an intermediate compartment 20.

The outer wall 19 is pierced with a lower opening 21, and the inner wall 18 is pierced with an upper opening 22. The side walls 15 and the bottom 14 of the post-combustion compartment 13 are lined with refractory bricks 23.

 The post-combustion compartment 13 communicates through an upper opening 24 with a gas evacuation pipe 25 in which a heat exchanger 26 is arranged. According to the embodiment shown in the figures, the exchanger is disposed entirely at the 'exterior of the post-combustion compartment 13, and has two side faces licked by the exhaust gas. Fluid inlet 27 and outlet 28 conduits supply the heat exchanger to be heated.

 The operation of the device is as follows: the logs placed in the chamber 1 are progressively distilled and heated, and the gases produced pass between the interstices formed between the bricks 12 of the support grid 9. The lower part of the chamber 1 is the part in which the combustion of the logs occurs, so that the bricks 12 are heated to high temperature by embers and flames. These bricks 12 promote the combustion of vapors and gases produced by the distillation of wood. This combustion is continued in compartment 13 by supplying outside air through the openings 21 and 22 of the door 17, the penetrating air being heated by its passage in the intermediate compartment 20. The gases are evacuated via line 25 after passage over the surfaces of the exchanger 26.

 The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below.

Claims (5)

 1 - Reverse combustion heating device, comprising an upper storage and distillation chamber (1) communicating at its base (4), by a support grid (9), with a lower post-combustion compartment (13) communicating itself with a gas evacuation pipe (25), characterized in that the support grid (9) comprises refractory bricks (12) separated.  2 - Device according to claim 1, characterized in that one has transversely a row of refractory bricks (12) parallelepiped disjoint between two angles (10, 11) lower support.  3 - Device according to one of claims 1 or 2, characterized in that the post-combustion compartment (13) is lined with refractory bricks (23).  4 - Device according to any of claims 1 to 3, the post-combustion compartment (13) of which comprises a lateral opening (16) closable by a door (17) for the evacuation of the ashes, characterized in that the door (17) has an inner wall (18) and an outer metal wall (19) separated by an intermediate compartment (20) communicating with the outside through a lower opening (21) and with the inside through an upper opening (22), so that post-combustion supply air enters the lower opening, heats up in the intermediate compartment and passes through the upper opening.  5 - Reverse combustion boiler for the production of hot liquid fluid according to one of claims 3 or 4, comprising a heat exchanger (26) subjected to the action of combustion gases, characterized in that the exchanger ( 26) is arranged in the gas evacuation pipe (25) downstream of the post-combustion compartment (13).