SE517021C2 - Device for combustion of granular solid fuel - Google Patents

Abstract

A device (3) for the combustion of granular solid fuel, for example wood flour pellets, chippings and the like, comprising a combustion chamber (16), an air inlet (24) having a fan (25) for providing air to the combustion chamber and for creating a predetermined through blowing of air through the combustion chamber before, during and after the combustion of the fuel, a dosing unit (12) for feeding of the fuel to the combustion chamber, an ignition device (28) for ignition of the fuel, a control and checking unit (32) for operation of associated or co-operating parts arranged in or at the combustion device and also an outlet (26) for hot combustion gases from the combustion of the fuel from the combustion chamber to a boiler section (27) in a heating boiler (6) for transfer of the heat to the heating system of the heating boiler (6), for example through water-cooled surfaces in the heating boiler. According to the invention, the combustion device (3) also comprises a movably arranged ash feeder (29) with a drive unit (30), controlled by the control and checking unit for automatic out feeding out of the combustion chamber of ashes, unburned fuel and slag products (31), which are created during the combustion of the fuel.

Description

20 25 30 35 517 021 P15os 2 pellets' content of boron and / or other fl-forming substances, ie. substances that lower the normal melting point of ash particles. Fuel pellets for combustion in domestic boilers are a domestic renewable environmentally friendly biofuel that does not add any net addition of carbon dioxide to the atmosphere and is manufactured, for example, from residual products from the construction and sawmill industry, e.g. saw and cutter shavings. The fuel pellets normally consist of about 10% water and about 12% pure carbon, while essentially the rest of the pellets consist of various hydrocarbon compounds. However, the content of the pellets varies greatly.

The sintering causes the openings necessary for the lu flow through the fuel core to become clogged and an accumulation of ash, unburned pellets and sintered slag to form. The more sintering, the more air must be added, which results in poorer efficiency for the burner as the combustion gases are diluted and as the added extra also acts as a cooler. It will be appreciated that in the case of combustion devices without a rotatable combustion chamber, the above-mentioned problems increase extremely markedly. The accumulation of ash, pellets and slag grows quite quickly so that a larger pile is formed therefrom, which can cause the position of the fuel core to be moved to a position unfavorable to the function, at the same time as the risk of backfire also increases dramatically, ie. that the fire hearth is lifted up towards and into the feed pipe for the fuel, which makes the sintering both technically difficult and also dangerous.

In many boilers there is a container in the form of a box inside the boiler and in which box the ash ends up when the front part of the burner is inserted into the boiler itself.

The ash in the box is emptied either manually or by a suction of the ash by means of a suction device. The ashtray can be relatively large, so it can be emptied relatively rarely without any inconvenience. The pellet consumption for combustion of fuel pellets with an energy content of approx. 4.7-5.0 kWh / kg is approx. 4 tonnes / year for a normal domestic boiler and with a normal ash content of 0.5-1.0% by weight, about a month without aslct emptying. By domestic boiler is meant here boilers that have burners with electricity of the order of about 5 - 20 kW. The pellet burners used today are normally intended for higher powers, about 30 kW, which is why they are unnecessarily large for use in normal domestic boilers.

It is thus realized that the clearly dominant problem for pellet burners is the sinter formation inside the burner itself. In a known construction with a fixed braking chamber, a removable grate is arranged, which grate forms a shelf with through-open openings and on top of which shelf the pellets fall down via a feed line. The described sintering clogs the openings in the rust, so this normally has to be taken out for cleaning every week, but sometimes this has to be done significantly more, which then causes great concern and irritation for the user. Therefore, it is desirable that the burner should operate without special measures for a longer period, for example the grate should not need to be removed and / or cleaned more than once a month.

The problem of sintering could possibly be reduced by certain additives in the actual pellet production, for example by mixing one or more substances which act as catalysts or are melting point raising, but since the willingness of the pellet manufacturers to correct said problems is low, measures must instead be taken in the burner. construction to eliminate or at least substantially reduce the problems resulting from said sintering of the ash.

OBJECT OF THE INVENTION AND ITS FEATURES The object of the present invention is to provide a device for burning solid, granular fuel, which device eliminates or at least substantially reduces the above-mentioned problems in accumulation of ash, unburned residues of fuel and other slag products such as sinter.

The device according to the invention is characterized in that the ash dispenser comprises a tubular front part, which is arranged in the lower space and which comprises a perforated bottom which constitutes the above-mentioned, inner bottom, which front part is arranged to be moved by means of the drive unit between at least one drive position, at said front part being arranged to close the lower end of the fireplace, and an ash emptying position, at which the fireplace is open downwards.

According to further aspects of a device according to the invention it applies that: - it is included in a plant for heating a building, which heating plant in addition to said boiler with associated heat transfer system comprises at least one further fuel supply and at least one fuel conveyor for automatic supply of fuel from the fuel supply to the fuel supply . - the combustion device in addition to or instead of the fuel conveyor and the fuel supply has a fuel supply built into the dosing unit. the dosing unit comprises a fuel feeder for dosing the fuel from the dosing unit and further into the combustion chamber via a feed pipe. 5 10 15 20 25 30 35 517 021 P1508 - the feed pipe is in the form of a preferably slightly inclined drop shaft along which the fuel falls freely a certain fixed length to prevent backfire. - in connection with the feed pipe, safety devices are provided which are included by a thermal guard that sounds an alarm if the heat spreads in the pipe and / or one or more dampers for closing the feed pipe. the fuel feeder is comprised of a feed screw, which is rotatably arranged between and adjacent to the upper end of said feed pipe at the dosing unit and either an inlet to the dosing unit or the bottom of the built-in fuel supply. The fl shaft comprises a speed-controlled motor and is mounted at the rear part of the combustion chamber for blowing and circulation of lu fi via said lu fi inlet and forwards and further out through the outlet at the other part of the combustion chamber fi- other part. one, fl era or preferably all of the boundary walls have perforations in the form of smaller holes and / or larger openings for the flow of lu fi. the igniter is located in the rear compartment at the rear restraint wall. the igniter is arranged in the lower compartment and in cooperation with the ash dispenser. the igniter is arranged inside the ash dispenser, the igniter accompanying the ash dispenser during its reciprocating movements. the rear boundary wall has lu fi openings into the igniter for the flow of air from the fl genuine, through the igniter and further into the fireplace. the igniter comprises an ignition coil for electrically heating the igniter. the ignition coil is designed as an induction heater. - the igniter has a housing with lu. inlet for blowing air from the kten genuine. the ash dispenser comprises a front part and one or fl elongate rods which are attached to and between the front part and the drive unit for the ash discharge. 10 15 20 25 30 35 517 021 P1508 - the upper part and the front end of each rod are arranged in the lower air space, while the drive unit and the rear end of each rod are arranged in a separate enclosure. the enclosure is arranged outside the heat-insulated combustion chamber at the rear outer wall and with each rod running through a hole in said rear outer wall. the front part has the shape of an upside down, rearwardly open box with three sides and an upwardly arranged perforated bottom, which bottom simultaneously forms the above-mentioned, movable inner bottom, where one side forms an upper edge from which the bottom and the the other two sides extend in the rearward direction towards the drive unit and where the sides are arranged at a distance from the longitudinal outer walls of the combustion chamber to form a downward continuation of the above-mentioned lu fi channels. - the drive unit comprises an främ xt front stop, two front and rear sliding sleeves movably arranged along each rod and a spring, which is arranged between the sliding sleeves, an eccentric, and an fi xt rear stop at the rear end of the rod. the eccentric comprises a pivot rod and two link arms, one of which is longer than the other, and that the two link arms are pivotally connected to each other at a common end, that the other end of the shorter link arm is attached to the pivot rod while the other end of the long link arm is rotatably anchored to the rear slide sleeve. - the drive unit has a motor for driving the eccentric via the pivot rod and thus the reciprocating movements of the front part.

ADVANTAGES OF THE INVENTION; The solution of constructing an ash dispenser which removes the ash, sintered deposits and other possible unburned residues of the fuel out of the incinerator and over to the conventional ash boiler for ash constitutes a very simple construction with few parts. The burner is primarily intended to replace an oil burner in a conventional oil boiler, ie. the basic idea is that a pellet burner is mounted in a conventional boiler instead of the now commonly used oil burner.

This gives a burner that is small, easy to maintain and very efficient, which in addition to the ash meter essentially contains only fl shaft, igniter and dosing unit, so the burner is both cheap to manufacture and also very reliable. The risk of backfire is also almost completely eliminated.

LIST OF FIGURES The invention will be described in more detail below with reference to the accompanying figures where: Figs. 1 is a schematic view of parts of a combustion device for a solid fuel installed at a conventional heating system for a villa, which heating system also has a fuel storage, conveyor, boiler and chimney. is a schematic cross-section through parts of an combustion device according to the present invention for use in a heating plant according to Fig. 2 figure 1. is a schematic cross-section through of parts of the combustion device according to figure 2 where the required air circulation is shown in more detail.

F ig. 4 a - f schematically show the procedure for a box and slag discharge of the combustion device according to figure 3, Fig. 3 DETAILED DESCRIPTION OF DESCRIPTION Referring to Fig. 1, a schematic view of parts of a conventional plant 1 for heating a building 2, e.g. a villa, installed device 3 for combustion of solid fuel in the form of granular material, for example compressed wood flour pellets or briquettes, ice and the like with a suitable diameter of about ø 6 - ø 12 mm, which heating system 1 also has a relative to the combustion device 3 exposed fuel storage 4, at least one fuel conveyor 5, a conventional boiler 6 with known heat transfer system (not shown), for example a radiator-provided water circulation system comprising water-cooled surfaces in the heating element 6, and a chimney 7 for formed flue gases.

The fuel conveyor 5 comprises a motor 8 with gearbox for driving a conveyor screw 10 rotatably arranged in a rigid feed pipe 9 for automatic supply of fuel from the fuel supply 4 via a downcomer pipe 11, suitably in the form of an excipient hose, to a smaller dosing unit 12 in the combustion device 3. The fuel conveyor 5 can also be designed with transp your transpoit screws 10 of any length for operational crisis and space-dependent reasons. Feeding with a conveyor screw 10 is, according to experts, the best alternative from an operational and safety point of view, but other types of known fuel conveyors can of course also be used in the combustion device 3 according to the invention. 10 15 20 25 30 35 517 021 7 P1508 Vid den i ñg. 2, the combustion device 3 can also, or instead of the described fuel conveyor 5 with extreme fuel supply 4, have a smaller fuel supply 13 built into the dosing unit 12 itself, which can be filled manually, then normally 1-2 times per week.

The dosing unit 12 comprises a further fuel feeder 14 with drive motor 15 for automatic dosing of the fuel from the dosing unit 12 and further into a substantially horizontal combustion chamber 16 arranged below this via a feed pipe 17.

The feed pipe 17, which opens into the top part of the combustion chamber 16, is in the form of a preferably slightly inclined drop shaft along which the fuel, after feeding the correct fuel dose by the fuel feeder 14, falls freely a certain definite length to prevent backfire. Additional safety means are provided in connection with the feed pipe 17. These comprise, for example, a ternovar 18 which sounds an alarm if the heat spreads upwards in the pipe 17 and one or more dampers 19 for closing the feed pipe 17. In the embodiment shown in figure 2 the additional fuel feeder is included 14 of a feed screw 20, which is arranged substantially horizontally and rotatably between and adjacent to the upper end 21 of said feed pipe 17 at the dosing unit 12 and either the inlet 22 of the downcomer pipe 11 to the dosing unit 12 or the bottom 23 of the built-in smaller fuel supply 13, if such is provided. .

The combustion device 3 comprises, in addition to said dosing unit 12 and combustion chamber 16, a lu fi inlet 24 with a 25 genuine 25 for supplying lu fi to the combustion chamber 16 for the combustion of the fuel and transporting the combustion gases and the gas ash formed therefrom via an inlet chamber 16. in a boiler space 27 in the boiler 6 for transferring the heat of combustion to the heat dissipation system of the boiler 6 (not shown), an automatic igniter 28 for igniting the fuel, a movably arranged ash dispenser 29 with drive unit 30 for discharging slag products, ash and unburned fuel 31 out of the combustion chamber 16 and further into the boiler 6 and a control and control unit 32 for substantially fully automatic operation of the combustion device 3 and in and at this certain or all included or cooperating parts.

The control and monitoring unit 32 constitutes a known microprocessor-based device with sensors required for the function, for example the thermal monitor 18, and is not described in more detail here, however it should be mentioned that by means of said unit 32 a fully automatic system is obtained via the boiler 6 15 20 25 30 35 517 021 P1508 the dewatering of the slag products 31 to the ash container 61 of the boiler 6, including the possibility of för your pre-programmed power stages, for example 9, 12, 18, 23 kW.

The fan 25, which is mounted at the rear part 33 of the combustion chamber 16 for blowing in and circulating lu fi via said lu fi inlet 24 and forward and further out through the outlet 26 at the front, upper part 34 of the combustion chamber 16, has a silent, speed-controlled motor 35 with a built-in tin socket which breaks in case of overload. The combustion chamber 16 comprises partly outer walls 36, which preferably provide a substantially externally box-shaped combustion chamber 16, partly inner boundary walls 37 and a movable inner bottom 45, which are later arranged at a certain distance from the outer walls 36 for division (see fi g. 2 and 3) of the thus double-walled combustion chamber 16 in a front, a rear and a lower cavity 38, 39, 40 and two air ducts 41, 42 along the longitudinal sides of the combustion chamber 16. In a preferred embodiment the combustion chamber 16 is formed externally by a square tube of square cross-section with the width about 160 mm. One, fl era or preferably all of the boundary walls 37 have perforations in the form of smaller holes and / or larger openings 43 for the flow of air (see fi g. 3.). The boundary walls 37, of which one or only one is arranged outwardly and with a downward and inward inclination from the inside of the roof 48 of the combustion chamber 16 or from the insides of one, several or all of the outer walls 36, enclose an inner, preferably downwardly funnel-shaped portion 44 of the combustion chamber 16. , which inner part together with a bottom 45 forms a fireplace for the combustion of the fuel. The bottom 45 of the fireplace 44 constitutes rust, ie. the usually grid-shaped bottom 45 on which a fuel core 46 rests during combustion and intermittent or continuous air flow. The mouth 47 of the feed pipe 17 is suitably arranged in the roof 48 into the fireplace 44 and in close connection with one or more of the insides of the inner boundary walls 37, which inclination of the inner wall (s) 37 is intended to provide a direction towards the fuel core 46 of the dosing unit 12 the fuel in a controlled manner. The upper, wider funnel end of the fireplace 44, at the front, upper part 34 of the furnace chamber 16, is open into the boiler space 27 and thus constitutes the above-mentioned outlet 26 for the combustion gases.

The igniter 28 for the automatic ignition of a quantity of precipitated fuel determined on the grate 45 from the dosing unit 12 (see Figure 4e), hereinafter referred to as igniter 49, is suitably arranged in the rear air space 39 at the rear limiting wall 37a.

After ignition, the ignition set 49 constitutes the fuel hearth 46 mentioned above. optimal lu fi current. The igniter 28, 10 15 20 25 30 35 517 021 Pisos 9 in the embodiment shown in the figures, comprises an ignition coil 50 of some known kind, for example comprising a so-called cantilever wire for electrically heating the igniter 28 to a temperature of about 800 ° C, the cantilever wire maintaining a temperature of around 100 ° C. The ignition coil 50 may also be designed as an induction heater (not shown).

The ash dispenser 29 comprises a front part 51, hereinafter also called straight, and one or more elongate rods 52 which are attached to and between the front part 51 and the drive unit 30 for the ash discharge. The razor 51 and the front end of each rod 52 are arranged in the lower space 40, while the drive unit 30 and the rear end of each rod 52 are arranged in a separate enclosure 53, suitably arranged outside the heat-insulated combustion chamber 16 at the rear outer wall 36a and with each rod 52 running through a hole 60 in the same 36a. The upper part 51 has the shape of an upside down, rearwardly open box with three sides 54, 55, 56 and an upwardly arranged, perforated bottom, which bottom simultaneously forms the above-mentioned grate 45. A side 54 forms a front, substantially vertical edge fi from which the bottom 45 and the other two sides 55, 56 extend in the rearward direction towards the drive unit 30. The longitudinal sides 55, 56 are arranged at substantially the same distance from the longitudinal outer walls 36 of the combustion chamber 16 as the longitudinal inner boundary walls 37 to form a continuation downwards of the above-mentioned air ducts 41, 42. The ash dispenser 29 comprises two end positions, an upper position, the operating position 58, at which the rake 51 closes the lower end of the fireplace 44, see fi g. 4a, and a rear position, the ash emptying position 59, at which the fireplace 44 is substantially completely open downwards, see fi g. 4c, between which end positions 58, 59 the razor 51 is arranged to be moved by means of the drive unit 30 via the rods 52.

The igniter 28 can also be arranged inside the ash dispenser 29, the igniter 28 accompanying the ash dispenser 29 during its reciprocating movements under the fireplace 44.

The igniter 28 has a housing 71 with lu fi inlet 72 for blowing lu fl from the kten shaft 25.

The drive unit 30, see 3 and 4, comprises an axle front stop 62 at each rod hole 60, suitably consisting of the partition 36a between the combustion chamber 16 and the enclosure 53, two front and rear sliding sleeves 63, 64 movably arranged along each rod 52 and a spring 65, which in the embodiment shown in Figs. End. The two link arms 68, 69, one of which is substantially twice as long as the other 69, are rotatably connected to each other at one of their ends. The other end of the shorter link arm 69 is attached to the pivot rod 67 10 15 20 25 30 35 517 0211 Pl508 Û while the other end of the long link arm 68 is rotatably anchored to the rear slide sleeve 64. The drive unit 30 also has a motor not shown for driving the eccentric 66 via the pivot rod 67 and thus the reciprocating movements of the razor 51.

FUNCTIONAL DESCRIPTION The function and use of the combustion device 3 according to the invention is as follows.

By means of the electronics relevant to the boiler 6 and controlled by the control and the control unit 32, the combustion device 3 starts and stops automatically or the setting of the operating tin state of the heating system 1. Before starting the combustion device 3, the ash dispenser 29 has been moved to its front operating position 58, see Figure 4a, so that the bottom 45 of the fireplace 44 is closed and the fuel feeder 14 has supplied fuel to the dosing unit 12, see Figure 1. At start-up, a certain smaller amount of fuel in front of the transport screw 10 of the dosing unit 12, see Figure 2, driven by the engine 15, which amount falls out of the feed pipe 17 so that a ignition set 49 required for ignition of the hearth 46 is formed on the bottom 45 of the fireplace 44 in front of the openings 57 in the rear boundary wall 37. to the igniter 28, see Figure 4e.

The igniter 28, see Figures 2 and 3, is initiated, whereby the ignition coil 50 is heated strongly to about 750-800 ° C, which takes about 2 minutes. When the correct temperature of the ignition coil 50 is reached, the motor 35 of the spigot 25 is started so that lu fl is blown in through the air inlet 24 to the rear air space 39 and further into the air inlet 72 in the housing 71 of the igniter 28, up to and past the ignition coil 50. Thus no lu fi is blown. during the heating of the ignition coil 50, as this would only cool it. Alternatively, the fuel can also be fed while the ignition coil 50 is heated up to the intended temperature and until an igniter set 49 with a suitable combustion time is obtained on the bottom 45 of the fireplace 44.

After about 2 minutes, the spigot 25 is started so that short, intermittent bursts of very hot air are forced out and / or up through the igniter 49 via the openings 57 and the holes 43, depending on whether the igniter 28 is mounted in the rear (shown in Figures 2). -4) or the lower space 39, 40 (not shown). When the fuel of the high air temperature reaches its ignition temperature, which takes about 1 minute, the igniter 49 is caused to ignite. More specifically, a primary combustion of the fuel takes place on top of the grate 45, whereby the fuel emits the combustion gases which are then ignited. Already after about 3 minutes it lights up normally, but the ignition coil 50 still runs up to fi ill time (5 min) for safety. When the approx. After the ignition of the combustion gases, these are therefore brought to a secondary combustion in the form of a fire emission through the outlet 26 of the air currents directed by the flame 25, the air chambers 38, 39, 40 and the air ducts 41, 42. Continued operation then takes place by the control unit 32 and the heating thermostat 6 of the boiler 6 causing the dosing unit 12 to dose the required amounts of fuel at the correct interval to reach the set temperature. Thus, for example, at full power output, certain fuel doses are fed into the fireplace 44 at such fixed intervals that the fuel core 46 burns continuously. At lower power requirements, the burner 16 does not have to be in continuous operation, so the fuel core is allowed to go out. The automatic ignition of a igniter 49 thus takes place at the start of the heating system 1, at certain specified times during its operation and after unplanned power outages, which is controlled by the control and control unit 32.

After the secondary combustion of the combustion gases, it is desired that essentially all fuel has been converted into flue gases with only a small fl gas ash as residue, which ash residue accompanies the flue gases out into the boiler space 27 and to the ash container 61. There, however, this is not always the case. , as explained above. During ignition, the ignition coil 50 becomes approximately 800 ° C and the edge holding wire then reaches a temperature of around 100 ° C.

The edge content wire can not withstand more than 1200 ° C, as the magnesium oxide in the wire melts if it rises above 1200C. The extinguished fuel hearth 46 with unburned fuel and the ash and sinter 31 formed during the last driving period before the stop form a pile on top of the bottom grille 45 of the fireplace 44, i.e. rake 51, which pile 31 grows as the boiler 6 is used. Each new igniter 49, which is dosed down, ends up in a smaller pile slightly further back on the bottom 45 on top of the sintering 31. The new igniter 49 thus constantly expands the pile 31 and also closes the holes 43 and the openings 57 further, so that the hot lu får current increasingly difficult to push and start the ignition of each new igniter 49. The fuel is thus free from direct contact with the ignition coil 50.

Before restarting, and after the ignition coil 50 has cooled, the drive unit 30 causes the rake 51, which forms both the bottom 45 of the fuel and the ash dispenser 29 of the slag products 31, to move back and forth, during which movement air is blown simultaneously so that the holes 43 and the openings 57 are not clogged. There is negative pressure inside the heating element 6, so the air must be forced in by means of the spout 25 to the front part 51 of the ash dispenser 29 and then further into the fireplace 44 via the grate holes 43 and up through the fuel hearth 46. 10 15 20 25 30 35 517 021 Pisos 12 De the double walls 36, 37 of the combustion chamber 16 further form loop channels 41, 42 around the box-shaped grid rake 51, through which channels 41, 42 the spout 25 feeds air along the sides 55, 56 of the grid box 51 to the front air space 38 and further in from the front air space 38 holes 43, but also through the holes 43 in the longitudinal sides 37 of the fireplace 44. In the operating position 58 the grate 45 is completely sealed along the inner walls 37 into the fireplace 44, as the grate box 51 is slightly wider than the inner walls 37 so that fuel does not fall outside and next to the grid box / rake 51. The rake 51 is first moved backwards so that the ash, slag and sinter 31 are scraped against the rear inner wall edge 37a, which acts as an abutment, and down in front of the rake 51 while this fo At the ash emptying position 59, substantially the entire rake 51 'is retracted within the rear boundary wall 37a, after which the rake 51 is caused by the drive unit 30 to turn and return in the forward direction, and then at least to its driving position 58. or even slightly longer, preferably at least level with the front outer wall 36 of the combustion chamber 16, while the ash, slag products and the unburned fuel 31 are pushed in front of the rake 51 and further down into the ash container 61 of the boiler 61. The rake 51 then returns to the initial position. i.e. operating mode 58.

The slag is discharged during a break in operation, normally about every 30 minutes, after the temperature has first been lowered in the brake chamber 16. At a temperature of 200 ° C reached, a 30 second blow is first blown so that the blow gas blows out. The slag 31 has then solidified and remains. The thermostat turns on and off maybe 6 times in the summer and up to 24 times in the winter. 30 min operation, 30 min cooling, 24 hours per day.

For the embodiment shown in Figures 3 and 4a-f, the more detailed function of the drive unit 30 is as follows: During operation of the combustion device 3, the two link arms 68, 69 of the drive unit eccentric 66 are directed forwards, towards the combustion chamber 16. When starting a ash emptying activates the guide and control unit 32 motor of the drive unit 30, which rotates the pivot rod 67 (according to fi g. 4a) so that the eccentric 66 via the link arms 68, 69 pushes the grate box 51 backwards from its front operating position 58. At the ash emptying position 59 the two link arms 68, 69 directed completely backwards. The fireplace 44 is completely open and the slag products 31 that were left after the reindeer blowing before the return of the rake 51 began are now in front of the rake 54. The pivot rod 67 continues to rotate so that it pulls the rod 52 in the forward direction until the original position, i.e. diifrläget 58, again taken. By, in an alternative and not shown embodiment, using one or two slightly longer rods to the drive unit, the ash dispenser can be made to reach all the way to the level of the front outer wall of the combustion chamber, before the straight position of the straight arms is assumed, at which position the link arms in this particular case a mutual angle greater than zero and less than 180 °.

If the forward movement of the rake 51 is prevented by an excessive accumulation of slag products and unburned fuel 31 falling in front of the rake 51 during the rearward movement, the spring 65 allows the eccentric to make a full turn, after which the guide and control unit 32, or a not shown switch, that the ash emptying movement is repeated until a full stroke has been obtained for the rake 51, i.e. that the razor 51 is reciprocated between its maximum end positions 58.59 determined by the length of the included rods 52.

ALTERNATIVE EMBODIMENTS The invention is not limited to the embodiments shown, but it can be varied in various ways within the scope of the claims. It is understood, for example, that by a conventional boiler 6 is meant here, for example, a so-called oil boiler for villas 2 where the ordinary oil burner is replaced by a burner 16 for solid fuel, preferably pellets, and where the heat transfer system, for example the existing waterborne system, is used just as with regular oil heating. The pellet burner 16 is in this case installed with connection to the normal operating thermostat of the boiler 6. Of course, no use is made of the use of the combustion device 3 to only existing boilers 6, but the combustion device 3 can also be used in all new installations of applicable heating systems 1.

Claims (23)

517 021 14 P1508 PATENT CLAIMS Device for combustion (3) of granular solid fuel, for example wood flour pellets, ice and the like, comprising a combustion chamber (16) comprising partly outer walls (36), partly inner limiting walls (36) and a inner bottom (45), which inner boundary walls (37) and inner bottom (45) are arranged at a certain distance from the outer walls (36) for dividing the thus double-walled combustion chamber (16) into a front, a rear and a lower one. air spaces (38, 39, 40) and two air ducts (41, 42) arranged along the longitudinal sides of the combustion chamber (16), which boundary walls (37) and inner bottom (45) enclose an inner part (44) of the combustion chamber (16) for forming of a fireplace (44) for the combustion of the fuel, lutein inlet (24) with fl spout (25) for supplying air to the combustion chamber (16) via the air spaces (38, 39, 40) and the air ducts (41, 42) for providing a predetermined lu fi flow through the combustion chamber 16), a dosing unit (12) for feeding fuel to the combustion chamber (16), an igniter (28) for igniting the fuel, a control and control unit (32) for operating in hot combustion gases in the combustion device (3) and at its components included or cooperating therefrom from the combustion of the fuel from the combustion chamber (16) to a boiler space (27) in a boiler (6) for transferring the heat to the boiler's heat transfer system, for example via water-cooled surfaces in the boiler (6), a movably arranged ash dispenser (29) with drive unit (30) ), controlled by the control and monitoring unit (32), for automatic discharge of ash, unburned fuel and slag products (31) formed during the combustion of the fuel out of the combustion chamber (16), characterized in that the ash dispenser (29) comprises a movable front part ( 51), which is arranged in the lower space (40) and which comprises a perforated bottom which constitutes the above-mentioned inner bottom (45), which front part (51) is arranged to be moved by means of the drive unit (30) between t an operating position (58), in which said upper part (51) is arranged to close the lower end of the fireplace (44), and an ash emptying position (59), in which the fireplace (44) is open downwards. Device according to claim 1, characterized in that it comprises a plant (1) for heating a building (2), which heating plant (1) in addition to said boiler (6) with associated heat transfer system further comprises at least one fuel storage (4) and at least one fuel conveyor (5) for automatic feeding of the fuel from the fuel supply (4) to the dosing unit (12). 10 15 20 25 30 35 P1508 517 021 1s Device according to claim 2, characterized in that the combustion device (3) has, in addition to or instead of the fuel conveyor (5) and the fuel supply (4), a fuel supply (13) built into the dosing unit (12). 4. Device according to claim 1, 2 or 3, characterized in that the dosing unit (12) comprises a fuel feeder (14) for dosing the fuel from the dosing unit (12) and further into the combustion chamber (16) via a feed pipe (11). . Device according to claim 4, characterized in that the feed pipe (17) has the shape of a preferably slightly sloping downhole outside which the fuel falls freely for a certain fixed length to prevent backfire. . Device according to claim 4 or 5, characterized in that in connection with the feed pipe (17) there are safety means arranged which are comprised by a thermal guard (18) which sounds an alarm if the heat spreads in the pipe (17) and / or one or more dampers. (19) for closing the feed pipe (17). . Device according to claim 4 in combination with claim 3, characterized in that the fuel feeder (14) is comprised of an feed screw (20), which is rotatably arranged between and in connection with said upper end (21) of said feed pipe (17) at the dosing unit ( 12) and either an inlet (22) to the dosing unit (12) or the bottom (23) of the built-in fuel supply (13). . Device according to any one of the preceding claims, characterized in that the shaft (25) comprises a speed-controlled motor (35) and is mounted at the rear part (33) of the combustion chamber (16) for blowing and circulating air via said air inlet (24) and forward and further out through the outlet (26) at the front part (34) of the combustion chamber (16). . Device according to one of the preceding claims, characterized in that one, fl era or preferably all of the boundary walls (37) have perforations in the form of smaller holes and / or larger openings (43) for the flow of air. Device according to one of the preceding claims, characterized in that the igniter (28) is arranged in the rear air space (39) at the rear boundary wall (37a). 10 15 20 25 30 35 517 021 P1508 15 Device according to claims 1-9, characterized in that the igniter (28) is arranged in the lower air space (39) and in cooperation with the ash dispenser (29). Device according to claims 1-9, characterized in that the igniter (28) is arranged inside the ash dispenser (29), the igniter (28) following the ash dispenser (29) during its reciprocating movements. Device according to claim 10, characterized in that the denbalure boundary wall (37a) has open openings (57) into the igniter (28) for the flow of air from the ((25), through the igniter (28) and further into the fireplace (44). . Device according to any one of the preceding claims, characterized in that the igniter (28) comprises an ignition coil (50) for electrically heating the igniter (28). Device according to claim 14, characterized in that the ignition coil (50) is designed as an induction heater. Device according to one of the preceding claims, characterized in that the igniter (28) has a housing (71) with a lu inlet (72) for blowing air from the kten (25). Device according to one of the preceding claims, characterized in that the ash dispenser (29) comprises one or more elongate rods (52) which are attached to and between the front part (51) and the drive unit (30) for the ash discharge. Device according to claim 17, characterized in that the front part (51) and the front end of each rod (52) are arranged in the lower air space (40), while the drive unit (30) and the rear end of each rod (52) is arranged in a separate enclosure (S3). Device according to claim 18, characterized in that the enclosure (53) is arranged outside the heat-insulated combustion chamber (16) at the rear outer wall (36a) and with each rod (52) running through a hole (60) in said rear outer wall. (3 6a). 517 021 Pl508 Device according to one of Claims 17 to 19, characterized in that the front part (51) has the shape of an upside-down, rearwardly open box with three sides (54, 55, 56) and an upwardly arranged, perforated bottom, which bottom simultaneously forms the above-mentioned movable inner bottom (45), wherein one side (54) forms a front edge 5 from which the bottom (45) and the other two sides (55, 56) extend in the rearward direction towards the drive unit (45). 30) and where the sides (55, 56) are arranged at a distance from the longitudinal outer walls (36) of the combustion chamber (16) to form a downward continuation of the above-mentioned lu fi channels (41, 42). 10 Device according to one of Claims 17 to 20, characterized in that the drive unit (30) comprises an outer stop (62), two front and rear sliding sleeves (63, 64) movably arranged along each rod (52) and a spring (65), which is arranged between the sliding sleeves (63, 64), an eccentric (66), and an axial rear stop (70) at the rear end of the rod (52). 1 5 Device according to claim 21, characterized in that the eccentric (66) comprises a pivot rod (67) and two link arms (68, 69), one of which (68) is longer than the other (69), and that the two the link arms (68, 69) are rotatably connected to each other at a common end, that the other end of the shorter link arm (69) is fixed to the pivot rod (67) while the other end of the long link arm (68) is rotatably anchored to the rear slide sleeve ( 64). Device according to one of Claims 21 to 22, characterized in that the drive unit (30) has a motor for driving the eccentric (66) via the pivot rod (67) 25 and thus the reciprocating movements of the front part (51).