RU2731686C2 - Solid fuel burner - Google Patents

Abstract

FIELD: power engineering.SUBSTANCE: burner for burning solid fuel, mainly pellets and chips, comprises at least two grate rods (25) arranged parallel to each other between inner walls (1), which are installed in holes of flange (7) of burner and on rod-bearing beam (24). Cleaning comb (22) performs following motions between grate rods (25): upwards through grate rods (25), then in direction of burner outlet, then downwards under grate rods (25) and further towards flange (7) of the burner, in which fuel flows down by gravity down to funnel (8) and opens fire-prevention valve (9), and by means of piston (11), having at least one hole for secondary air (15), which serves also for cooling of piston (11) and channel for piston (12), falls on grate rods (25), wherein ash, which got through grate rods (25) on bottom (30), by means of fan (13) is blown through opening of gate (20) hole in bottom (30) of burner.EFFECT: invention allows complete fuel combustion and slag crushing to its solidification.8 cl, 10 dwg

Description

Technical area

The present invention relates to a burner operating on the new principle for burning solid fuels, in particular, but not exclusively, wood chips and pellets, which may also have a lower ash melting point than that provided for in class A2 according to EN 14961-2. These are, for example, granules from agricultural waste, peat and others, which have an ash melting point below 1100 ° C.

State of the art

A pellet burner is known from the prior art, which is designed to burn solid fuels, in particular pellets (WO 02/079693 A1). The burner consists of hollow grate rods, mutually parallel at equal distances, through which primary air flows. Hollow grate rods are located above the ash space and form a grate, and the primary air, after passing through the hollow grate rods, is directed through a perforated plate located in the front part of the burner in the combustion chamber.

Combustion of fuel with a low ash melting point in this and other similar burners leads to ash melting and the formation of slag, which gets into the gaps between the grate bars and / or into the holes in the plates (for example, IWABO villa - C1; ECOVARM - e) and stops air access for burning. Cleaning of such burners can only be done with compressed air from the compressor. This leads to two problems: the cycling burner and the noise like a shot every time the burner is cleaned, and there are also known cases where the perforated plates overheat and deform from high temperatures.

One attempt to solve this problem with fuels with a low ash melting point can be found in both sliding grate burners (e.g. IWABO VILLA-S2; ECOVARM-E +) and inclined grate burners (e.g. HERZ Pelletstar boiler). The disadvantage of these burners is the cyclic operation of the burner - after burning a certain amount of pellets, the burner is filled with ash and / or slag. After that, the burner enters the "damping" mode, the combustion process stops and the burner is cleaned. The worse the pellets, the shorter the combustion phase. For some pellets, such as peat pellets, the time for ignition, burnout and cleaning is longer than the time during which the fuel burns. This leads to a decrease in power (for example, if the burner is in the combustion phase for only 20 minutes in one hour, and in the ignition phase, burnout phase and cleaning phase for the remaining 40 minutes).

Known burners for solid fuels, in particular for chips and pellets, which have movable grates (for example, HERZ Firematik. Strebel Taurus). When moving, every second grate pushes fuel and / or coal forward. The upper grate should clean the lower grate. In slag-forming fuels, slag, ash and speckled fuel often stick together into the mass covering the burner, which obstructs the air supply. There are cases when the slag sticks to the lower grate, and the upper grate slides over the adhering slag. Thus, a large amount of air passes between the two grilles, and they burn out.

In addition, molten ash (slag) "wraps" part of the fuel. The slag impedes the flow of air to the fuel on the grate and this fuel is not burned. Thus, we have a higher percentage of unburned fuel in the ash box.

Another attempt to solve the problem of slagging of the burner is the Vemer A251 boiler. Its burner has a movable grate that passes through the grate, moves linearly forward and upward, and then returns back. This grate is to remove slag from the burner grate. In fact, slag is removed only from the grate slots, but remains on other parts of the grate. Often the slag adheres to the movable grate and moves back and forth with it until the air supply is obstructed. In addition, there are cases when, due to a too long stroke of the movable grate, slag, molten ash and fuel adhered to them are thrown out of the grate, thereby interrupting combustion.

Somewhat better results in the combustion of slag-forming fuel are shown by the burner described in patent KR 100541280, which has a grate cleaning device in the form of a cleaning comb, which performs circular movements between the grate rods. This design has the following disadvantages:

a. The cleaning comb cannot clean the grate bars that remain between the blades of the cleaning comb.

b. All moving parts are located in the combustion chamber at very high temperatures (over 1000 ° C) and therefore have a short service life.

c. All moving parts are in the same space as fuel and ash. Thus, ash falls not only under the grate bars, but also on moving parts such as sprockets, chains, shafts and drives, and causes intense wear.

KR 100901365 discloses a fuel hopper flap that can be opened by compressed air and serves as a burnout protection. The use of compressed air in the fuel bunker is undesirable for light fuels (wood chips, pellets), since, firstly, this can cause a reverse fuel ejection, and secondly, it leads to an uncontrolled ingress of additional air into the combustion chamber.

A kiln is known from JP 2000266333, in which ash is blown out through an opening in the lower part of the kiln, which is opened by a downward-falling flap. This design does not allow installing the burner in a boiler with a low burner door, since there is no free space under the burner.

A burner with two pistons is known from US Pat. No. 1,441,293. The lower piston is connected to a sliding grid element, with primary air entering the sliding grid through holes in the lower piston. The upper piston is used for refueling and does not have an air hole. Thus, it is subjected to high thermal stress.

These problems are solved with the help of the invention specified in paragraph 1 of the claims.

The advantages achieved by the invention are, in particular, that the coals and molten ash located on the grate are mixed by the cleaning ridge. Thus, two effects are achieved: more complete combustion of the fuel and crushing of the slag before it solidifies. By moving the cleaning ridge over the grate in the direction of the burner opening, ash and slag are removed from the burner. According to the invention, it is achieved that if the slag adheres to the upper part of the grates, it is removed from the grates by the cleaning comb during the rotation of the grates. The cleaning comb always moves over the grate in one direction towards the exit of the burner, and under the grate goes back and forth.

The fuel is fed to the grate by means of a piston. When the piston is at rest, it closes the funnel opening and thus provides fire protection.

The piston has at least one secondary air hole at the end. The air passing through the piston cools it and the piston bore, which prevents fuel particles from sticking.

The fuel slides through the funnel under the influence of gravity, since the inclined wall has an angle of inclination that is greater than the angle of natural destruction. The fuel funnel at the bottom has a larger opening than the top. This prevents the funnel from blocking.

The funnel has a fire damper, the shaft of which is installed in such a way that the fire damper rests on the inclined wall. Thus, the fire damper closes the funnel and opens only when pressure from the top of the fuel appears.

All the moving parts of the burner are located in areas through which the combustion air passes and thus they are cooled.

An embodiment of the invention is explained in more detail with reference to the figures.

FIG. 1 shows a burner according to the invention in side section with an eccentric shaft and a pivot shaft.

FIG. 2. View of the burner from the side of its outlet, in partial section.

FIG. 3. Side section of the burner with eccentric shaft and pivot shaft, cleaning ridge and piston at rest.

FIG. 4. Side section burner with two eccentric shafts.

FIG. 5. Side section of the burner showing the movement of the cleaning ridge.

FIG. 6. Side section of a funnel with a fire damper.

FIG. 7. Cleaning comb and grate rods with cleaning comb at the bottom (at rest).

FIG. 8 Cleaning comb and grate bars with the cleaning comb up.

FIG. 9. Destruction and mixing of the slag and coal layer.

FIG. 10. Removal of slag from rotating grate rods through a cleaning comb.

The invention relates to a burner for burning solid fuels, in particular, pellets and wood chips, which may also have a ash melting point below standard.

The burner has at least two grate rods 25, which are installed parallel to each other at a distance and into which primary air 26 enters. The grate rods 25 are located between the inner walls 1 of the burner and are installed in the holes of the burner flange 7 on the rod-carrying beam 24. Inner walls 1 have at least one opening 2 for secondary air 5. The inner walls 1 together with the outer walls 3 form a channel for the secondary air 5.

The grate rods 25 can be rotated by the interaction of the slag particles adhering to them and the moving cleaning ridge 22, or the grate rods 25 can be rotated by a drive.

All moving parts are located either under the grate rods 25 or in the channel between the inner wall 1 and the outer wall 3 and are thus cooled by the primary air 26 flowing through the grate or by the secondary air flowing through the channel 12.

The cleaning comb 22 is at rest under the grate rods 25 and is cooled by the primary air 26 flowing through it. The cleaning comb 22 performs the following movements: upward through the grate rods 25, breaks the slag and coal layer 29 on the grate rods 22 and mixes the slag and coal layer 29 on the grates 22. After that, the cleaning comb 22 moves towards the burner outlet and removes the slag 28 from the burner, and then moves down under the grate and further towards the burner flange 7. This movement of the cleaning ridge 22 can also be circular.

The burner is closed from above with a cover 4, which is located on the inner walls 1.

Flange 7 is used for mounting the burner on a boiler or on another device. Most of the burner parts can be mounted on the flange 7, for example, a flame detector 6, an ignition unit 17.

The fuel, which is supplied to the funnel 8, under the action of gravity enters the secondary air hole in the piston 15 in the channel 12 for the piston 11, which pushes it onto the grate rods 25.

The area with parts of the burner on the opposite side of the flange 7 is closed by the body 10. The body 10 is tightly mounted to the flange 7, and the funnel 8 and the fan 13 are also tightly mounted to the body 10.

Protection against burnout is carried out by closing the fuel hole in the channel 12 of the piston 11 at rest, as well as by the fire valve 9 and the fan damper 14.

During the cleaning phase, gate 20 opens an opening in the bottom 30 of the burner, and the ash trapped between the grate rods 25 on the bottom 30 is blown out of the burner with the help of the fan 13.

FIG. 1 and 2 show the burner from the side and from the side of the burner outlet. The cleaning comb 22 is driven from the eccentric shaft 16 and the pendulum bar 18. The eccentrics of the cleaning ridge 22 and the pendulum bar 18 are offset relative to the axis of the eccentric shaft 16. Thus, the effect is achieved that when the right side (in the figure) of the cleaning comb 22 is at the top , the pendulum bar 18 rotates to the right, and the pivot axis 19 raises the left (in the figure) part of the cleaning ridge 22 up.

FIG. 3 shows the burner from the side with the eccentric shaft 16 and the pendulum bar 18, with the cleaning ridge 22 and the piston 10 at rest. For the cleaning ridge 22, the resting state is under the grate bars 25, where it is cooled by the primary air. For piston 10, the resting state is the end point in the direction of the burner opening (as shown in the figure).

FIG. 4 shows the burner from the side with two eccentric shafts 16 and 27 which drive the cleaning comb 22.

FIG. 5 shows parts of the burner (cleaning ridge 22 and grates 25) and possible movements of the cleaning ridge 22.

FIG. 6 shows a side view of funnel 8 and fire damper 9 in the closed position (Fig. 6a), open position (Fig. 6c), and the gravity vector in the open position (6c).

FIG. Figures 7 and 8 show parts of the burner (cleaning comb 22 and grates 25) from the side and positions when the cleaning comb 22 is lower (Fig. 7) or higher (Fig. 8) of grates 25.

FIG. 9 shows the crushing and mixing of the slag and glow coal layer 29 located on the grate rods 25 by the cleaning ridge 22 during its upward movement. 9a shows the cleaning ridge 22 at rest under the grates 25 before it begins to move upward. 9b shows the cleaning ridge 22 above the grate bars 25 after it has mixed the slag and coals layer 29.

FIG. 10 shows the removal of adhered slag 28 to the grate rods 25 using a cleaning comb 22. FIG. 10a shows the slag adhered to the top of the grate 25, FIG. 10b shows the grate 25 already turned, FIG. 10c shows the slag 28 already removed from the grate 25 and the position of the cleaning ridge 22 in position above the grate 25.

Positions:

1 inner wall

2 holes for secondary air

3 outer wall

4 burner cover

5 secondary air

6 flame detector (e.g. photo sensor)

7 burner flange

8 funnel

9 funnel valve

10 burner housing

11 piston

12 piston channel

13 fan

14 fan flap

15 hole for secondary air in the piston

16 eccentric shaft

17 ignition block

18 pendulum bar

19 rotary axis

20 gate

21 axial channel

22 cleaning comb

23 bar support

24 burner front wall

25 grate rods

26 primary air

27 eccentric shaft

28 slag

29 layer of slag and coals

30 burner bottom

Claims (8)

1. A burner for burning solid fuels, mainly pellets and wood chips, containing at least two parallel to each other between the inner walls (1) grate rods (25), which are installed in the holes in the flange (7) of the burner and on the rod-bearing beam (24 ), characterized in that the cleaning comb (22) makes the following movements between the grate rods (25): upward through the grate rods (25), then in the direction of the burner outlet, then downward under the grate rods (25) and further towards the flange (7 ) a burner, in which the fuel flows under the action of gravity down into the funnel (8) and opens the fire damper (9), and by means of a piston (11) having at least one hole for secondary air (15), which also serves for cooling the piston (11) and the channel for the piston (12), falls on the grate rods (25), while the ash that has fallen through the grate rods (25) on the bottom (30) is blown out with the help of the fan (13) through the gate opened ( 20 ) hole in the bottom (30) of the burner. 2. Burner according to claim 1, characterized in that the grate rods (25) are driven into rotation by the interaction of the slag (28) adhered to the grate rods (25) and the cleaning ridge (22). 3. Burner according to claim 1, characterized in that the grate rods (25) are rotatably mounted and rotated by the drive. 4. The burner according to one of paragraphs. 1-3, characterized in that the movement of the cleaning ridge (22) is circular. 5. The burner according to one of paragraphs. 1-4, characterized in that the cleaning comb (22) is driven by an eccentric shaft (16) with eccentrics offset relative to the axis of the eccentric shaft, and a pendulum bar (18) with a pivot axis (19). 6. The burner according to one of paragraphs. 1-4, characterized in that the cleaning comb (22) is driven by eccentric shafts (16) and (27). 7. The burner according to one of paragraphs. 1-6, characterized in that the funnel (8) in the lower part has a larger opening than in the upper one, while the axis of the fire damper (9) is located in such a way that the fire damper (9) rests on the inclined wall under its own weight, moreover, the inclined wall is located at an angle that allows the fuel to drain. 8. The burner according to one of paragraphs. 1-7, characterized in that all movable parts are located under the grate rods (25) and / or between the inner walls (1) and the outer walls (3) in the air flow zones.

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