EP0798510B1 - Heating boiler - Google Patents

Abstract

The filler shaft (1) is filled with solid fuel, especially wood. A flow path leads from the filler shaft to a waste gas flue (11). The flow path leads via a combustion zone (9) and subsequent heat-exchange zone (10). The combustion zone with upward flow has at least one chimney-type combustion shaft (12) with vertical axis. The lower end of the combustion shaft is connected to the filler shaft by at least one inflow duct (13) opening into it at a tangent. Secondary air is introduced to the combustion shaft by at least one ventilation hole (15).

Description

The invention relates to a boiler with a solid fuel, in particular wood, fillable and combustible with combustion air, filling chute set up for bottom-side burn-off, from one to one Exhaust outlet leading flow path that goes through a Filling shaft adjacent, with combustion gases and secondary air Combusable combustion zone with flow from bottom to top and one of these subordinate heat exchange zone leads, the Combustion zone at least one with a standing axis, has a chimney-shaped combustion shaft at its lower end via at least one tangentially opening inflow channel with the Filling shaft is connected.

A boiler of this type is known from CH 671 822 A5. At this known arrangement, the combustion shaft through two pipes formed, which delimit an annular space in which secondary air circulate can. This is sucked in through recesses in the inflow channel one with the annulus surrounding the combustion shaft communicating annulus is surrounded. The secondary air must be here overcome comparatively large flow resistance. With natural Train is therefore sucked in comparatively little secondary air, which too poor mixing of the secondary air with the combustion gases and leads to lack of air in the combustion zone. The consequence of this are therefore overall poor combustion and high CO and Dust pollution of the exhaust gas. If so by using a blower counteracted, arise in addition to the high Deployment effort also involves high running costs, which is unfavorable which affects profitability.

A similar arrangement is known from DE 31 47 410 A1, in which the Combustion zone through the entire width of the filling chute flanking chamber is formed, which is narrowed on the inlet and outlet side. The Partition between this chamber and the filling shaft ends above of the grate that delimits the filling shaft downwards, so that a over the entire width of the filling shaft, down from the grate limited passage gap results from which the narrowed chamber inlet after goes off upstairs. The secondary air is called over the entire length of the Passage gap fed. In the chamber of the combustion zone this results in a straight, rotation-free flow. this leads to for a short dwell time with poor heat transfer and one bad mixture formation and thus overall bad Afterburning in the designated chamber. The the narrowing of this chamber on the output side is said to have this disadvantage somewhat weaken, but leads to an increase in flow resistance the disadvantages already outlined above.

From AT 394 775 B a boiler is known in which the combustion zone an insert made of refractory material with a with a lying axis arranged, drum-shaped chamber that contains one end a tangential connection to the filling shaft and at the other end has an upward opening. In the drum-shaped chamber results in a spiral flow axial and rotary component. The thermal buoyancy of the Combustion gases here, however, mean that the flow in the lower Circumferential area is not as good against the drum wall as in the upper one Circumferential area, so that the heat storage capacity of the drum wall is not used optimally. There is therefore one in the lower peripheral area to fear comparatively poor afterburning. That could only can be counteracted by increasing the speed. To one However, maintaining sufficiently fast rotation is a high pull required, which is often not available as a natural train, so that a blower is also required here, which adversely affects the required Effort. Another disadvantage of the known The arrangement can be seen in the fact that the insert containing drum-shaped chamber practically a one-piece, over the entire boiler width extending block is executed what the Assembly extremely difficult. It can also be assumed that that in the known arrangement an increase in the length of the drum-shaped chamber and / or the drum radius inevitably an increase in the width and / or depth and thus the base area of the boiler performs what in terms of space constraints Boiler rooms is undesirable.

Proceeding from this, it is therefore the object of the present invention a boiler of the type mentioned with simple and inexpensive To improve means so that not only good afterburning, but also a space-saving design can be achieved.

This object is achieved in that the in Fireproof material provided combustion shaft over at least a ventilation hole provided on the floor side and close to the wall Secondary air can be acted upon.

With the combination according to the invention the disadvantages of known arrangements avoided while preserving their advantages. Due to the retention of the standing arrangement of the Combustion shaft or the combustion shaft comes here thermal lift of the combustion gases to support the train, so that already with normal natural train high Flow rates can be achieved. These result in more advantageous Way in the bottom area of the combustion shaft to an effective Vacuum zone, so that a sufficient amount of secondary air reliably is sucked in. The amount of secondary air drawn is in advantageously automatically dependent on the gas throughput, so that self-control results. The through the assigned ventilation holes Secondary air flowing in in a nozzle-like manner advantageously has one high penetration and is accordingly intensive with the Combustion gases mixed so that there is a good one Mixture preparation and good afterburning result. Here comes the high heat storage capacity of the Combustion shaft containing refractory material advantageous for Wear. The spiral shape that forms in each combustion shaft Current flows over the entire circumference of the Combustion shaft close to the shaft wall, what the Improved heat transfer and thus an excellent Afterburning guaranteed. The consequences of this are advantageous low CO and dust pollution of the exhaust gas. Another advantage is to be seen in the fact that here the combustion shaft or Combustion zone containing combustion chambers by type of Stacked stones can be formed what a easy assembly and a performance-related modular design enables. It can be reliably ensured that all of them existing combustion ducts are operated in full load range, so that condensation and chimney sooting are excluded.

Advantageous refinements and practical training of overriding measures are specified in the subclaims. So can advantageously several, parallel chimney-shaped combustion shafts be provided in the form of an adjacent filling wall parallel row are arranged. This also results in use several, preferably the same combustion shafts a simple and particularly compact design. At the same time, these enable Measures an even distribution of the inflow channels over the Width of the neighboring filling shaft wall, which is necessary to achieve a uniform combustion in the filling shaft is beneficial.

Another advantageous measure can be that the inflow channel or the inflow channels each have a rectangular cross section have a greater height than width. This advantageously results in a slim flow band close to the wall, what a good one Heat transfer is beneficial.

Each combustion shaft can advantageously have several, on one Hole-shaped ventilation holes arranged near the wall pitch circle be assigned. Due to the larger number of ventilation holes these have a comparatively small diameter, so that a nozzle-like function gives what is good for achieving Mixture formation is beneficial.

Another advantageous embodiment of the higher-level measures is that the height of the combustion shaft or the combustion shafts from the level of the hopper floor to the upper one Boiler area extends. This results despite high flow velocities a high dwell time. On an outlet-side narrowing of the combustion shaft or the combustion shafts can therefore be advantageous Be waived, which also increases the associated Flow resistance comes away.

Further advantageous refinements and practical training of overriding measures are in the remaining subclaims specified and can be found in the example description below.

Figur 1

einen Vertikalschnitt durch einen erfindungsgemäßen, mit Holz beheizbaren Heizkessel und

Figur 2

einen Querschnitt entlang der Linie II/II in Figur 1.

A preferred exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Here show:

Figure 1

a vertical section through an inventive, wood-fired boiler and

Figure 2

a cross section along the line II / II in Figure 1.

The boiler according to the invention has, as can best be seen from FIG is, a filling chute 1, which has an upper, through a swivel cover 2 closable filling opening with logs etc. can be loaded. The lower end of the filling shaft 1 is formed by a grate 3, below which is an ash collecting space 4. The filling burns during operation the filling chute 1 from below, i.e. forms on the grate 3 Fire bed. The grate 3 can be pivoted for adjustability his.

The air required for combustion is supplied to the boiler in the form of Primary air and secondary air are supplied as indicated by arrows 5 and 6 is indicated. The primary air inlet is in the front area of the boiler arranged, preferably adjustable ventilation flap 7 formed. The primary air enters the filling shaft as upper air and / or lower air 1, as indicated by the arrows 5 a, b. The secondary air gets wider injected downstream, as will be explained later.

The volatile combustion products withdraw from the filling shaft 1, such as is indicated by the arrow 8. The filling shaft is in the near-rust area Provide a flow outlet in the area of its rear wall. The from Filling duct 1 outgoing flow path leads over a filling duct 1 adjacent combustion zone 9 and a heat exchange zone arranged downstream of this 10 to one in the area of the upper end of the rear boiler wall arranged, outgoing outlet port 11. The combustion zone 9 is designed so that afterburning takes place, so that the flue gas emerging at the outlet port 11 is only slight Residues of CO and dust. In the heat exchange zone 10 a heat transfer medium, water in the example shown, heated.

The combustion zone 9, which is located in the back of the filling shaft 1 adjoining boiler area contains at least one with chimney-shaped combustion shaft 12 arranged upright, the one at its lower end by one transverse to its axis arranged, horizontal inflow duct 13 with the filling shaft 1 connected is. The upper end of the combustion shaft 12 is open without restriction. The bottom 14 of the filling shaft 12 is approximately at the level of the grate 3 that closes the filling chute 1 downwards.

The above-mentioned secondary air is in the area of the combustion zone 9 fed. For this purpose, the one above the secondary air inlet connected distribution channel 21 arranged bottom 14 of the Combustion shaft 12 with at least one with a vertical axis, that is parallel, 12 bore-shaped to the axis of the combustion shaft Provide ventilation hole 15 through which secondary air can flow in, such as is indicated by the arrow 6b. The axial direction of the ventilation hole 15 crosses the lying axis of the inflow channel 13. The in the direction of Arrow 8 from the filling shaft 1 into the combustion shaft 12 Combustion products flowing in are as a result of the standing Arrangement of the combustion shaft 12 deflected upwards and flow along due to the effective pull and their thermal buoyancy high speed downwards.

The combustion shaft 12 is accordingly from bottom to top flows through. In the deflection area of the combustion chamber 12 inflowing combustion products result from the high Flow velocity is a negative pressure at the bottom. This causes that the secondary air is drawn in automatically, depending on the situation throughput of combustion products. This results in a Self-control, so that adjustable control elements in the secondary air area can be dispensed with. The ventilation holes 15 inflowing secondary air practically crosses the mass flow of incoming combustion products, which ensures good mixing and thus achieved a good mixture formation for the afterburning become. In order to keep the mixture in the Combustion shaft 12 and thus as complete as possible To ensure afterburning, the combustion shaft extends 12 to the upper boiler area. The upper, open end 16 of the Combustion shaft 12 is located approximately in the example shown the level of the rear outlet port 11. The clear cross section of the Combustion shaft 12 is the same over the entire height, so that no narrowing. Here is a circular cross section provided so that there is a cylindrical combustion shaft configuration results.

The inflow channel 13 is, as can best be seen from FIG of the circular cross section of the combustion shaft 12 tangentially arranged so that the incoming combustion products on the circular Wall of the combustion shaft 12 guided along and accordingly are set into a rotational movement. Because at the same time, as mentioned above, there is an increasing movement, there is practically a spiral movement indicated near 17 in FIG. 1 at 17 inside the combustion shaft 12. As a result of the rotation This results in good wall contact and therefore good heat exchange with the wall of the combustion shaft 12, which is positive the reliability of afterburning regardless of throughput affects.

To ensure a good admixture of secondary air, here are how Figure 2 can be seen further, several bottom ventilation holes 15 are provided. These can therefore have a comparatively small cross section have, so that rays with high penetration and thus a good mixing with those entering the combustion shaft 12 transversely thereto Combustion products result. The ventilation holes 15 are arranged on a pitch circle close to the wall, expediently only the near the filling shaft Half of the circumference of this sub-circle is occupied, since here the Suction is best.

In the smallest size of the boiler according to the invention, only one can Combustion shaft 12 may be provided. In the example shown, as FIG. 2 further shows, two cylindrical ones arranged side by side Combustion shafts 12 are provided. The side by side Combustion shafts 12 practically form one to the rear wall of the Filling chute 1 parallel row. Of course it would be conceivable, too to arrange more than two combustion shafts side by side. All the provided combustion ducts 12 are expediently the same educated.

Each combustion shaft 12 has an inflow channel 13 on the bottom assigned. The inflow ducts 13 of all combustion ducts 12 are arranged so that their inlet cross-sections 13a, practically form the exit of the filling shaft 1, approximately evenly over the Distribute the filling shaft width, which spreads over the entire filling shaft width uniform burning guaranteed. The inflow channels 13 have expediently a rectangular cross section, the Cross-sectional height is greater than the cross-sectional width. This results in practically a slim flow band that fits neatly on the wall of the Filling chute 12 can create. All inlet channels 13 are expedient the same cross section. In the case of a symmetrical to a central plane Arrangement of the inflow channels 13, as shown in the example shown located in the combustion ducts 12 located next to one another opposite directions of rotation of the spiral flow 17, what for mixing the one at the upper end of the combustion shafts 12 escaping flue gases and thus an even application of heat the elements of the heat exchange zone 10 is beneficial.

The combustion shafts 12 with associated inflow channels 13 and Ventilation holes 15 are in a refractory material, for example Chamotte, existing insert 18 integrated. This extends in one piece across the entire boiler width and accordingly across all existing combustion ducts 12. It would also be conceivable, several inserts each containing only one combustion shaft to be placed side by side. This practically results in a modular structure, where the boiler width depends on the required output changed. Each insert 18 is expediently divided into several over the height Blocks divided, which are placed on top of each other like chimneys can, which makes assembly easier. The block structure of the Insert 18 or the inserts 18 results in a large, the combustion channels 12 surrounding material accumulation and thus a high heat storage capacity. As a result, even with long operating periods fluctuating throughput as high as possible Temperature and thus a reliable afterburning of the Combustion shafts 12 flowing gases reached as a result of spiral flow close to the wall into an intensive wall-side Heat exchange come.

In the example shown, as already mentioned above, as Heat transfer medium water can be used. The heat exchange zone 10 is accordingly with lamella-like, parallel to the rear wall of the filling shaft 1 arranged pockets 19 to which water can be applied Mistake. The insert 18 is here between the first and the second, the Filling shaft 1 facing pocket 19 arranged. These are accordingly in thermal contact with the insert 18. The others Pockets 19 delimit gap-shaped flow channels 20 between them the flue gases flow through here in parallel, which then to be deflected to the outlet port 11.

As shown in FIG. 1, the insert 18 is arranged at a distance from the floor. The Space below the insert 18 results in the entire width of the boiler continuous chamber which is connected to the secondary air inlet and thus acts as a distribution channel 21 through which the secondary air all ventilation holes 15 is distributed.

Claims (10)

1. A heating boiler with a filling chute (1) set up for bottom burn-up, capable of being filled with solid fuels, in particular wood, and receiving combustion air, with a flow path from the chute to an exhaust gas outlet (11), leading through a combustion zone (9) through which combustion gases and secondary air flow from bottom to top and which is adjacent to the filling chute (1) and leading downstream from the combustion zone through a heat exchange zone (10) where the combustion zone (9) has at least one chimney-shaped combustion chamber (12) arranged with a vertical axis, connected at its lower end to the filling chute (1) over at least one admission channel (13) which opens tangentially, characterized in that the combustion chamber (12), which is made of a refractory material, can receive secondary air through at least one ventilation hole (15) provided in the bottom near the wall.
2. A heating boiler according to claim 1, characterized in that the combustion zone (9) has several, preferably two parallel chimney-shaped combustion chambers (12) arranged in the form of a row parallel to the adjacent filling chute wall.
3. A heating boiler according to one of the preceding claims, characterized in that all the combustion chambers (12) are designed the same, preferably each as a cylinder having a uniform circular cross section over its entire height.
4. A heating boiler according to one of the preceding claims, characterized in that the combustion chamber (12) or the combustion chambers (12) each have a height extending from the level of the bottom of the filling chute (1) into the upper area of the boiler.
5. A heating boiler according to one of the preceding claims, characterized in that the admission channels (13) that are present are uniformly distributed with their inlet cross sections (13a) over the width of the respective wall of the filling chute (1).
6. A heating boiler according to one of the preceding claims, characterized in that an admission channel (13) is provided for each combustion chamber (12).
7. A heating boiler according to one of the preceding claims, characterized in that each admission channel (13) has a rectangular cross section with a height that is greater than its width.
8. A heating boiler according to one of the preceding claims, characterized in that each combustion chamber (12) has a plurality of bore-like ventilation holes (15) arranged on a partial circle, preferably in the area of the circumferential area of the partial circle facing the filling chute (1).
9. A heating boiler according to one of the preceding claims, characterized in that the combustion zone (9) has at least one insert (18), preferably lined with stackable bricks and containing at least one combustion chamber (12) made of a refractory material.
10. A heating boiler according to claim 9, characterized in that the insert (18) is arranged between two pockets (19) of the heat exchange device (10) having additional pockets (19) arranged in a staggered pattern one after the other with a distance between them which forms a flow gap (20).

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