Single chamber heater for manual feeding of solid fuels with additional vertical grate

Abstract

Single chamber heater for manual feeding of solid fuels comprising a combustion space (1) defined by side walls (7) and a front wall (4), a horizontal grate (5) at the lower part and a rear wall (2) provided at the lower part above the horizontal grate (5) with a vertical grate (13) consisting of vertical ribs (8) adjacent to one side (8.1) to the rear wall of the combustion space (1), where a space is formed between the vertical ribs (8) facing into the combustion space (1), where the space between vertical ribs (8) is formed by channels (9) which on the side facing the combustion space (1) are terminated by a through vertical gap (11), wherein the clearance of channels (9) behind the through vertical gap (11) is at least 10% greater than the width (11.1) of the through vertical gap (11).

Description

Technical field

[0001] The invention relates to a single chamber heater for manual feeding of solid fuels with an additional vertical grate, in particular a wood stove.State of the art

[0002] The concept of single chamber heaters with manual feeding of solid fuels is widespread. It is mostly used in conventional stoves, fireplaces, cookers and hot water boilers. It is usually used for heating houses and similar buildings. The fuel is most often lump wood.

[0003] Known heaters of this concept usually have a square or rectangular chamber. The inner space of the chamber is the combustion space. The bottom of this combustion space is either integral or contains a grate. The grate may be solid or with movable elements. Below the grate is an ash space into which leads inlet of primary combustion air. Usually one of the side walls contains a feed opening with a door, often made of glass. The ceiling of the combustion space contains an opening for the escaping of flue gas. Secondary combustion air inlets are most often located at the top of the front wall, where they also rinse the glass of the door, and the rear wall of the combustion space. The grate and walls of the combustion space are made of heat resistant material (metal or ceramic). The ash space has a removable container for keeping the ash (ash pan).

[0004] In conventional heaters, the flame usually flows through the entire fuel load and shortly after the fuel is fed, the entire layer of the fed fuel ignites (the fuel starts to burn on the surface of all fed pieces). The combustion of the fed fuel is thus not uniform over time (as for example in the case of double chamber heater), which reduces the combustion quality and efficiency. In order to achieve an acceptable quality of combustion in these heaters, it is necessary to feed smaller pieces of fuel and more frequently (e.g. every 45 min). This reduces the useful value of the heater. Feeding of more amount of fuel (in an attempt to extend the feeding interval) increases the described combustion unevenness and negatively presents in lower efficiency and combustion quality

[0005] Some well-known single-stage heaters are equipped on walls of the combustion chamber with vertically provided ribs (with a profile height of 5-10 mm). The ribs prevent the fuel (logs) from leaning near to the wall and thus limiting the air access to the adjacent part of the fuel and thus local suffocation of the flame, or cause local smoke (imperfect combustion). The purpose of the ribs is therefore to improve the quality of combustion.

[0006] One of the best known heaters with ribs in the lower part of the back wall of the combustion chamber is the Czech wood stove of brand IK VERNER from 2010. The back wall of the fireplace of this stove contains in the lower part dimensionaly significant ribs (20-30 mm high). The ribs are rectangular or trapezoidal in horizontal section, tapering into the fireplace.

[0007] The purpose of these dimensionaly significant ribs is to create a sufficiently large space between the back wall of the combustion chamber and the fuel bed, through which a significant portion of air and flame flows during operation to promote combustion of the fuel bed near the back wall at the expense of the remaining fuel volume. In other words, to ensure that the fuel bed burns gradually from the rear wall of the fireplace to the front wall and not uniformly throughout the whole volume as in conventional fireplaces. This gradual burning allows larger batches of fuel to be added, which then burn for longer periods of time. The purpose of the ribs is therefore to extend the burning time.

[0008] The disadvantage of ribs of VERNER brand is that they do not achieve the described effect of combustion control to a sufficient extent. The space between the ribs becomes clogged during operation and subsequently clogged with the fuel fragments (cinders). The impassable space between the ribs does not fulfil the function of channels and thus does not provide the basic function of the grate (in this case the function of vertical grate), ensuring the required controled combustion. The space between the ribs is usually already blocked by hot cinders when the feeding is applied, so it is necessary to make passageways free manually with a suitable fireplace tool. This makes operation very difficult. The space between the ribs is sometimes more, sometimes less clogged also during operation, because the added fuel breaks up into smaller particles which slip down and jam in the space between the ribs. To achieve gradual combustion in this heater is difficult for service. When this heater was certified by the State Testing Institute of the Czech Republic, it was achieved a burn time with feeding interval of only 45 min, as it is the case with most other heaters of this type.Summary of the invention

[0009] The shortcomings of known single chamber heaters are largely eliminated by a single space heater for manual feeding of solid fuels containing a combustion space defined by side walls and a front wall, a horizontal grate at the bottom and a rear wall provided at the bottom above the horizontal grate with a vertical grate consisting of vertical ribs adjacent to the rear wall of the combustion space on one side, where a space is formed between the vertical ribs facing the combustion space. The essence of the invention is that the space between the vertical ribs is formed by channels which are on the side facing the combustion space terminated by a through vertical gap, wherein the clearance of the channels behind the through vertical gap is at least 10% greater than the width of the through vertical gap. Channel clearance means the internal diameter of the channel which determines the maximum size of a circular object that can pass freely through it

[0010] Depending on the shape of the ribs, channels can be circular or quadrilateral in cross-section. If channels are circular, their diameter shall be at least 10% greater than the width of the through vertical gap of the vertical grate. For a circular channel, the clearance shall be equal to the diameter of the channel. If channels are quadrilateral in cross-section, it is advantageous from the point of view of manufacturing simplicity of the vertical ribs if the sides of the channel (quadrilateral) are mutually apart of at least 10°. For a quadrilateral channel, the clearance is equal to the diameter of the maximum circle inscribed in the quadrilateral.

[0011] From the point of view of combustion of the fuel and its sliding down from the vertical ribs into the combustion space, it is advantageous if the upper surfaces of the ribs of the vertical grate are sloped into direction to the combustion space at an angle of at least 40°.

[0012] The advantage of the invention is that the channels of the vertical grate do not become blocked and clogged with parts of the burning fuel (cinders). This is achieved by the fact that fuel particles which penetrate the gap inside the channel fall down into the ash space. As the vertical grate channels remain open throughout full time operation, sufficient volume of primary air flows through them to the rear part of the combustion space. This reduces the flow of flame through the fuel bed in favour of the flow of flame through the vertical grate channels and near to the rear wall. The combustion is therefore more uniform over time as the fuel layer burns off gradually, from the rear wall to the front.

[0013] The single chamber heater according to the invention allows to feed triple volume of fuel, which then burns for triple time in comparison to conventional single chamber heaters, without compromising combustion quality and efficiency.

[0014] During the certification of the heater according to the invention in the State Testing Institute of the Czech Republic, perfect combustion was achieved with a feeding interval of 120 min. Thus, the invention allows to extend the burning time almost three times compared to the existing single-stage heaters.Brief description of drawings

[0015] The invention will be further explained by reference to the drawings which illustrate: Fig. 1 spatial view of the combustion space of a heater with vertical grate Fig. 2 section of a single chamber heater through the vertical grate Fig. 3 the rib of the vertical grate of Fig. 2 in spatial view Fig. 3.1 the rib of the vertical grate of Fig. 2 in frontal view Fig. 3.2 the rib of the vertical grate of Fig. 2 in side view Fig. 3.3 the rib of the vertical grate in Fig. 2 in top view Fig. 4 the channel formed between the two ribs of Figs. 1 and 3 in spatial view, Fig. 4.1 the channel formed between the two ribs in Figs. 1 and 3 in frontal view Fig. 4.2 the channel formed between the two ribs in Figs. 1 and 3 in the side view Fig. 4.3 the channel formed between the two ribs in Figs. 1 and 3 in the top view Fig. 5. schematically shows the ribs with a through vertical gap and the width of the through vertical gap Fig. 6. top view of the grate with channels of quadrilateral cross-section as shown in Figs. 1 to 5 Fig. 7. top view of the grate with channels of circular cross-section Fig. 8. top view of the grate with channels of hexagonal cross-section Preferred embodiments of the invention

[0016] Figs. 1 and 2 show a single chamber heater for manual feeding of solid fuels, comprising a combustion space 1 defined at the bottom by a horizontal grate 5, a rear wall 2, side walls 7 (Figs. 6 to 8) and a front wall 4 with a feeding opening 3. The rear wall 2 of the combustion space 1 is provided in the lower part, above the horizontal grate 5, with a vertical grate 13 which consists of a number of vertical ribs 8 and between them channels 9 with a lower outlet 14 to the ash compartment 6 and an upper outlet 15 to the combustion space 1 are formed. Vertical ribs 8 are adjacent with one side 8.1 to the rear wall 2 of the combustion space 1. Between vertical ribs 8 on the side facing the combustion space, through vertical gaps 11 are formed. In order to avoid clogging of channels 9 with parts of burning fuel, the clearence of channels 9 behind the through vertical gap 11 is greater than the width 11.1 of the through vertical gap 11, in this particular case by vertical ribs 8 shown in Figs 3 to 5 by about 15%. That is, the largest circle that can be inserted into the perpendicular section of the channel 9 has a diameter by 15 % greater than the width 11.1 of the through vertical gap 11. Fuel particles that penetrate the through vertical gap 11 inside the channel 9 will fall down into the ash compartment 5 through the lower outlet 14.

[0017] Schematically, Fig. 5 shows in a front view a vertical grate 13 with vertical ribs 8 and width 11.1 of through vertical gap 11 In the example embodiment of vertical ribs 8 with lateral sides 10 in circular shape, these form a channel 9 of circular cross-section (Fig. 7). Clearance, in this example the diameter of channels 9 behind the through vertical gap 11 is 15% greater than the width 11.1 of the through vertical gap 11. In the example embodiment of vertical ribs 8 of quadrilateral cross-section, the channel 9 is also of quadrilateral cross-section (Fig. 6). Clearance, in this example the depth 21 of the channel 9 is 15% greater than the width 11.1 of the through vertical gap 11 and its lateral sides 10 mutually open at an angle 20° towards the rear wall 2 of the combustion space 1

[0018] For all example embodiments, upper surfaces 12 of vertical ribs 8 of the vertical grate 13 are sloped towards the combustion space 1 at an angle of 40°

[0019] The ceiling 19 of the combustion space 1 goes upwards to the front wall 4. At the highest point of the combustion space 1 there is a flue gas outlet 20. A secondary air inlet 17 is located above the feeding opening 3. The horizontal grate 5 in this particular embodiment comprises three movable grate elements 16 formed by shallow troughs pivotally mounted in the side walls 7. The horizontal grate 5 can be tilted slightly to any side. Below the horizontal grate 5 there is the ash compartment 6 which contains the primary inlet 18 of air. The upper surface 12 of vertical ribs 8 is sloped at an angle 40° towards the front wall 4 of the combustion space 1 see Fig. 3.2.

[0020] Although as a preferred embodiment of the invention the embodiment of channels of circular cross-section or a quadrilateral cross-section was described, the shape of channels in the form of a pentagon or other polygon is not excluded. Vertical ribs 8 may have either sharp edges or rounded edges. The function of the heater is as follows: Fuel, e.g. firewood, is fed through the feeding opening 3 into the lower part of the combustion space 1. Fuel is then ignited either by the operator or ignites itself from the glowing base layer of fuel left from the previous charge. Air flows through primary inlet 18 into the ash compartment 6, from where approximately 70% of the primary air flows through lower outlet 14 into channels 9 of the vertical grate 13. Remaining approximately 30% of primary air flows through gaps between movable grate elements 16. Primary air reacts with the fuel solids causing primary combustion which produces heat, mixture of combustion gases and combustible gases. Secondary air flows through the secondary inlet 17, mixes with combustible gases and causes secondary combustion. The stream of rising combustion gases produces a flame at the rear wall 2, which when cooled produces hot combustion gases. They leave the combustion space through the flue gas outlet 20. The ash from fuel accumulated on the horizontal grate 5 is removed approximately once a day by the operator by tilting movable grate elements 16 by means of an external operating element, and the ash is sliped down into the ash compartment 6. Particles of ash and fuel that reach the upper surface 12 of vertical ribs 8 of the vertical grate 13 slide down from its inclined surface onto the fuel bed. Fuel gradually breaks down into smaller and smaller pieces (cinders) during combustion. Some of these burning pieces of fuel (cinders) fall of the through vertical gaps 11 of the vertical grate 13 into the channels 9. Since the channel 9 behind the through vertical gap 11 has a greater clearance, the particles fall through the channel 9 to the ash compartment 6 through the lower outlet 14 where they slowly burn out. Thus, the channel 9 remains passable during the entire operation.List of relationship tags

[0021] 1 Combustion space 2 Rear wall 3 Feeding opening 4 Front wall 5 Horizontal grate 6 Ash compartment 7 Side wall 8 Vertical rib 8.1 Side of vertical rib 9 Channel 10 Lateral sides 11 Through vertical gap 11.1 Width of the through vertical gap 12 Upper surface 13 Vertical grate 14 Lower outlet 15 Upper outlet 16 Movable grate elements 17 Secondary inlet 18 Primary inlet 19 Ceiling 20 Flue gas outlet 21 Depth of the channel

Claims

1. Single chamber heater for manual feeding of solid fuels comprising a combustion space (1) defined by side walls (7) and a front wall (4), a horizontal grate (5) at the lower part and a rear wall (2) provided at the lower part above the horizontal grate (5) with a vertical grate (13) consisting of vertical ribs (8) adjacent to one side (8.1) to the rear wall of the combustion space (1), where a space is formed between the vertical ribs (8) facing into the combustion space (1) characterised in that the space between vertical ribs (8) is formed by channels (9) which on the side facing the combustion space (1) are terminated by a through vertical gap (11), wherein the clearance of channels (9) behind the through vertical gap (11) is at least 10% greater than the width (11.1) of the through vertical gap (11).

2. Single chamber heater according to claim 1, characterised in that the channel (9) is of circular cross-section.

3. Single space heater according to claim 1, characterised in that the channel (9) is of quadrilateral cross-section, wherein lateral sides (10) of the channel (9) are mutually apart of at least 10°.

4. The single space heater according to claims 2 and 3, characterised in that upper surfaces (12) of the ribs (8) are sloped towards the combustion space at an angle of at least 40°.

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