EP1975508B1 - Combination of a sectional boiler with a dust trap for airborne ash contained in the combustion fumes of a solid fuel boiler - Google Patents

Abstract

The trap (5) has baffles partially occupy a passage section of a reference compartment. The compartment exists between a rear surface wall of a front exchanger or an intermediate exchanger before an entry of combustion smoke in a furnace flue and a rear surface exchanger. A plate support (12) has deflectors (26-29) arranged in the baffle on a smoke path, and the passage section of gas and the smoke is provided in the compartment between an outlet of a combustion chamber and an inlet in the flue, where the passage section is found in a rear of a heat body of a boiler.

Description

The present invention relates to a dust trap in combination with a sectionalable boiler including cast iron operating with a solid fuel for example wood or coal.

It is known that the combustion of solid fuels, in particular that of wood, produces gases and combustion fumes loaded with solid particles.

If the heavy particles remain in the hearth and are discharged with the ashes, the lighter ones are carried away by the aeraulic flow and are deposited on the walls of the flues of the heating body on which the exhaust fumes charged with these particles, generally called particles, pass. fly ash.

These deposits are particularly abundant on the smoke path in cast iron boilers in which the aeraulic flow travels horizontally along the flues before escaping through the flue gas duct.

However, it happens that in these flumes, the exchange structures are horizontal or have horizontal fins, which further promotes the deposits to such a point that their frequent evacuation is necessary.

This necessity is too great a constraint for home heating and an appropriate solution must be found to avoid these deposits which cause a cleaning too frequent.

Numerous ways and numerous devices are known for dusting the fumes of the heavier flying solid particles.

First, there are a variety of methods and means for cleaning and washing fumes and other means for making the fumes clean by improved combustion, afterburning, gasification or pyrolysis.

These systems require expensive and complex equipment with possible chemical interventions. For others, you need a special burner.

There are then methods of physical separation by cyclone or others or by mechanical filters, liquid or electrostatic. These means are also expensive and require regular maintenance because the risk of clogging is often important.

Centrifugal dust collectors have good efficiency. However, they are noisy, cumbersome and expensive. In addition, difficulties remain to adapt the dust extraction performance to the current ecological requirements.

In addition, these techniques are either impossible to apply to domestic boilers or difficult to support from the economic point of view.

The following inventions of the state of the art are also known.

The patent GB 987.458 from IDEAL STANDARD relates to a sectional boiler with a second combustion chamber outside the main heating element. This second combustion chamber has a chamber and an ash pan for solid fuels below a grid. Slotted passages 29 are provided between the elements forming the heating body of the boiler for combustion gases and fumes. A plate 30 is disposed at a distance from the slotted passages 29 to prevent the passage of fly ash.

The patent US 2,959,140 In the name of Harry FRIEDBERG concerns a household incinerator without smell and without fumes. This incinerator includes a fly ash trap for particles larger than 25 microns and an afterburner for burning aerosols. The fly ash trap has baffles and a recovery compartment in which the fly ash falls by gravity. A post combustion device follows this ash trap in the form of a plurality of arch plates, mounted on a support and heated to incinerate the smallest particles.

The DE 31 14 345 in the name of HOVAL INTERLIZ refers to a waste boiler. Above the burner is an incineration chamber for waste limited by walls with openings 14. A wall 18 constitutes a baffle in the smoke outlet for precipitating the fly ash downwards.

The utility model German DE 200 11 518 in the name of BUDERUS also shows the existence of a transverse wall on the passage of fumes to trap large particles down.

The German patent DE 43 44 406 in the name of BIEWALD shows the existence of particle traps for fumes formed of a multitude of deflectors in the form of a register. These deflectors are more or less elaborate in their form so as to create baffle paths and vortices.

The utility model German DE 201 02 732 in the name of BUDERUS relates to a particle trap having a transverse wall forming a baffle in a chamber mounted on the flue outlet duct. The baffle is lined with a fine sieve and an ash recovery baffle formed of two convergent inclined walls leaving a longitudinal slot passage is in the lower part.

The object of the invention is to provide an effective, static, durable and reliable solution requiring no maintenance and at a lower cost.

To rid the fumes of these fine particles or dust likely to be deposited on the exchange structures, there is provided according to the invention a dedusting unit traversed by the fumes which, thanks to its baffles, performs a separation work of the particles in holding the heavier ones that fall to the bottom of the hearth. Thus, only the finest particles pass through the dust collector and are carried by the aeraulic flow in the flue gas duct.

These, particularly light, do not settle on the walls but on the contrary are evacuated outside in the same way as a volatile product.

The dust trap according to the invention can advantageously be made in the form of a separate part to be brought back to the back of the hearth on the upward path of exit of the fumes before their passage in the flues.

The heaviest particles, braked, fail to cross the passage in baffles and fall by gravity into the home from which they are removed by the ash removal device.

We thus find the advantages of a static assembly, reliable, compact, robust and low cost.

• la figure 1 est une vue en perspective du piège à poussières selon l'invention,
• la figure 2 est une vue en perspective de l'arrière montrant le piège à poussières en place à l'intérieur d'une chaudière, l'élément échangeur arrière de celle-ci étant dessiné en transparent,
• la figure 3 est une vue en perspective de l'intérieur de la chaudière en regardant vers l'élément échangeur arrière,
• la figure 4 est une vue en élévation montrant le piège à poussières selon l'invention en place, le trajet des fumées et des poussières étant visualisé par des flèches.

Other features and advantages of the invention will appear in the description which follows, given by way of example and accompanied by the drawings in which:

• the figure 1 is a perspective view of the dust trap according to the invention,
• the figure 2 is a perspective view of the rear showing the dust trap in place inside a boiler, the rear exchanger element thereof being drawn in transparent,
• the figure 3 is a perspective view of the inside of the boiler looking towards the rear exchanger element,
• the figure 4 is an elevational view showing the dust trap according to the invention in place, the path of smoke and dust being visualized by arrows.

The advantage of this invention lies in the ease of assembly and integration of this dust trap in the body of a sectionalable boiler, that is to say whose heating body is constituted by the succession of exchanger blocks assembled together, whose juxtaposed lower parts form the combustion chamber and whose juxtaposed upper parts form at least one stage of heat exchanger channels along which passes the airflow exiting the combustion chamber. These channels are traditionally called flues.

The boiler shown as a non-limiting example in the drawings is of low power. It has a heating body 1 having, according to the example, only three exchanger blocks, namely a front heat exchanger 2, an intermediate heat exchanger 3 and a rear heat exchanger 4.

Of course, the invention is not limited to a heat exchanger with three exchangers and exchanger here described as intermediate is more generally the penultimate exchanger. On the contrary, it extends to boilers of all powers that can exist.

The dust trap 5 according to the present invention can be mounted or placed by inserting into the existing space for the passage of flue gases and gases between the intermediate exchanger 3 or the last exchanger exchanger and the last exchanger 4.

It can be mounted and placed in different ways between the wall 6 of the rear face of the intermediate heat exchanger 3 and that facing the last exchanger.

In the embodiment shown in the figures, there are three parallel paths of flues, including two lateral flues 7 and 8 and a central flue 9 for evacuation.

Of course, the invention also applies to different interior arrangements and conformations.

The dust trap 5 can occupy in thickness all or almost all the width of a rear return compartment 10, that is to say the passage of combustion gases and fumes between the two exchangers 3 and 4. This rear compartment of 10 is defined as delimited by the rear heat exchanger 4 and the wall 6 of the rear face of the intermediate exchanger 3 to the inlet flues.

The following is the location of the trap 5 in the example shown in the figures but it should not be considered as limiting.

The dust trap 5 according to the invention is in the form of a folded sheet metal part 11 comprising a vertical support plane or support plate 12 ending upwards by two parallel oblique deflection and wedging wings 13 and 14 delimiting between them a recess 15. The oblique wings 13 and 14 serve as deflector and support.

They may possibly bear each on the shoulder 16 or 17 of a flue.

The support plate 12 is intended to serve as a back plate to the dust trap 5 according to the invention.

The support plate 12 has different perpendicular fins in the form of plane deflectors in an inclined position relative to the horizontal and arranged in a baffle so as to form two substantially symmetrical main passageways 18 and 19, with a space converging upwards between which is an upwardly diverging, dividing-gap return middle pathway 21 in the form of an upwardly angled open-angle dipping angle deflector facing upwards and placed in the middle position.

Each main channel 18 or 19 may be for example, but not necessarily, in alignment with the entrance of each corresponding flue. Each main passageway 18 or 19 is constituted from the bottom upward of a first stage in the form of two inclined deflectors converging upwards 22, 23 and 24, 25 forming a space narrowing upwards and opening onto a second stage formed of a transverse deflector and inclined 26,27 with respect to the flow direction and surmounted by a second deflector 28,29 quasi parallel but offset in space towards the central part forming a baffle 30, 31 each time.

Each planar deflector is a rectangular wafer of variable size and shape as shown in the figures.

The middle return channel 20 is partially occupied by the distribution deflector 21 and formed in its first part by a diverging space delimited by the deflectors 23 and 24.

The mechanical assembly formed of the support plate 12 and the deflectors has a thickness such that it occupies all or almost all of the thickness of the rear return compartment 10 through which the combustion gases and fumes pass.

The length of the dust trap 5 allows it to occupy the entire width of the rear deflection compartment 10 delimiting with adjacent deflectors end paths 32 and 33.

This structure and disposition in baffles slows the outgoing air flow, and forces it to divide and lose its charge in heavy particles.

Indeed, the presence of these flat obstacles in baffles together forming a sort of labyrinth forces the aeraulic current to follow many curved and elongated paths.

During the crossing of this baffle, the particles of a certain size removed from the combustion chamber by the airflow are sufficiently braked and abut against the walls.

This effect causes their descent by gravity against the upward entrainment of the aeraulic flow. They fall into an end receptacle of the ash disposal device or into the end space of the auger of the ash extraction and disposal device.

Thus an effective separation of particles contained in the fumes in fine volatile particles which are carried into the airflow to the flue gas and finer particles stopped by the dust trap and down to the ash collection and disposal device whose end is just below.

The arrows in solid lines on the figure 4 show well the ascending paths of the aeraulic flow and consequently those taken by the fine particles passing through the dust trap. These are carried to the flues 7 and 8 as shown by the arrows in broad lines halftone.

On the other hand, the heavier particles fall by the median channel 20 whose volume is converging downwards and by the end channels 32 and 33 constituting areas less subject to the pressure of the ascending aeraulic flow.

We will now examine the possible locations and arrangements of the dust trap according to the invention at the rear of the boiler heating body in the return compartment.

As can be seen in the figures, in the variant shown by way of example, the dust trap 5 is placed against the inner face of the last exchanger element 4. The deflectors 26 to 29 are in contact with this inner face. The only contact of the dust trap 5 with the rear face 6 of the intermediate element 3 is that of the oblique wings 13 and 14 forcing the fumes to pass through the baffles of the dust trap 5. It is supported on each side of its base in this position by transverse projections 34 and 35 of the last exchanger ( figure 3 ) and maintained in this position by the wedging resulting from support on the inner forms facing the exchangers concerned.

This location and this position concern the exemplary embodiment shown. They should not be considered as limiting. Indeed, various others are possible depending on the internal conformation of each exchanger.

Thus, it can also be envisaged that the support plate 12 comes to bear against the wall 6 of the rear face of the intermediate heat exchanger 3 or more generally of the penultimate heat exchanger of the boiler heating body and to wedge under or just below the entrance to the flues.

It can also be maintained simply by wedging in the rear return compartment 10, and this between the rear wall wall 6 and the rear heat exchanger 4. The wedging can result from the support of the oblique wings 13 and 14 on the shoulders 16 and 17 inlet flues and a wedging support against the rear face of the last exchanger 4.

The oblique wings 13 and 14 then make the connection with the inlet flues.

Of course, the invention is not limited to the particular means described but on the contrary embraces all variants.

Claims (10)

1. Combination of a sectional boiler with a dust trap, having sections with flue ways, for instance central and lateral ones, and working with solid fuel, for separating the flying ash of the fine particles contained in the combustion fumes, characterized by a piece including deflectors which occupy, at least partially, the passage section of a return compartment (10) existing between the back wall (6) of the last but one section or intermediate section (3) before the entry of the fumes into the flue ways and the back of the last section (4), the dust trap (5) having the form of a support plate (12) including baffles arranged on alternate sides on the path of the fumes, which baffles occupy in the width, totally or partially, the passage section of the gas and combustion fumes in the return compartment (10) between the exit of the combustion chamber and the entry into the flue ways and which are in the rear of the body of the boiler.
2. Combination of a sectional boiler with a dust trap according to claim 1 characterized in that it is placed above the end of the collecting and discharge device for the ash of the boiler.
3. Combination of a sectional boiler with a dust trap according to claim 1 or 2 characterized in that the support plate (12) carrying the baffles arranged on alternate sides, proceeds upward by two oblique deviation and adjustment wings (13) and (14) forming a baffle on both sides of a hollow (15).
4. Combination of a sectional boiler with a dust trap according to claim 1 or 2 or 3 characterized in that it is placed in the rear of the last section (4), the back of the support plate (12) looking towards the back (6) of the last but one section and leaning on transversal protrusions (34) and (35) of the rear section.
5. Combination of a sectional boiler with a dust trap according to claim 1 or 2 or 3 characterized in that the two oblique deviation and adjustment wings (13) and (14) forming a baffle, lean on the back of the last but one section (3) or the entry of the lateral flue ways (7) and (8).
6. Combination of a sectional boiler with a dust trap according to claims 1 or 2 or 3, characterized in that the baffles are arranged diagonally according to two symmetrical main passage paths (18) and (19), separated by a middle return way (20) in which a deviator is placed (21), the end baffles delimiting each time an end way (32) and (33) with the adjacent wall of the section.
7. Combination of a sectional boiler with a dust trap according to the previous claim characterized in that the baffles are arranged in levels, of which a first level is formed by two groups of two aslant baffles (22, 23) and (24, 25) delimiting between each other each time a space narrowing upward, and a second level formed by two groups of two baffles (26, 28) and (27, 29) in transversal position in relation to the general passage direction of the flow in the first level and staggered in space to each other.
8. Combination of a sectional boiler with a dust trap according to claim 6 characterized in that the middle return way (20) and the end paths (32) and (33) are convergent downwards while the main passage paths (18) and (19) are convergent upwards.
9. Combination of a sectional boiler with a dust trap according to claim 6, characterized in that the deviator (21) is a dihedron looking upwards and placed in middle position.
10. Combination of a sectional boiler with a dust trap according to claim 7, characterized in that the baffles of each first group of each level are arranged convergent on the path of the fumes and in that the end baffles of these groups each time form a space converging downwards with the adjacent wall of the section, realizing the end paths (32) and (33) for the descent of the dusts towards the furnace.

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