SE1851459A1 - Device and method for continuous combustion of combustible material in a pyrolytic chamber - Google Patents

Abstract

A device (1) for combustion of a combustible material, comprising, inner walls (3) and outer walls (4), creating a double wall space (15) in between, which double wall space is provided with at least one primary air inlet (8), a top wall (17) having at least one top opening (10), an inclined tubular means (2), which tubular means (2) further comprises an inlet (5) for the combustible material in the upper part of the inclined tubular means (2), an inlet cover (51), a pyrolytic chamber (6) located on the inside of the inner wall (3) of the tubular means, an outlet (7) in the lower part of the inclined tubular means, and an outlet cover (72), and wherein the double wall space (15) comprises a secondary air distribution zone (9) for distribution of hot air and facilitating mixing of pyrolytic gases, a combustion zone (11), and a flame zone (12), and wherein at least one of the inner walls (3) comprises through holes (13) to let hot air flow into the secondary air distribution zone (9). The invention also comprises a method for combustion of a biological material in a device according to the invention, and collecting biochar from the device.

Description

DEVICE AND SYSTEM FOR CONTINUOUS COMBUSTION OF COMBUSTIBLE MATERIAL IN APYROLYTIC CHAMBER The present invention relates to a device and a system for combustion of combustible ma-terial in a pyrolytic chamber, wherein the combustion can be continuous. lt further relates to a system BACKGROUND Around 3 billion people around the world are dependent on traditional cooking stoves and2 billion tons of biomass are burned each year. Exposure to air pollution is typically up to100 times more than recommended as healthy by WHO. For some of these people, up to40% of the income for the household is spent on fuel and up to 5 hours each day are spent on collecting fuel.

Wood or other biomass are put into stoves, flames ignited and burn directly (direct burningof solid fuels) producing flames used for cooking with ash as final -byproduct or residue left.The design ofthese could start from just 3 stones on which a pot is put, then cylinders withpot stands and main inlet for biomass, mainly wood, and sometimes with heat insulationaround the cylinder. Gradually cookstoves have been improved with special air inlets and special forms all to achieve energy efficiency and reduce smoke.

Biochar cookstoves (also classified as pyrolytic cookstoves or biomass gasifier cookstoves)operate under a thermochemical process called pyrolysis or pyrolytic combustion. Pyrolysisis the burning of biomass (wood, waste...other biomass forms) in the absence of, or verylimited, oxygen conditions which results in simply extracting a mixture of different gas mol-ecules within the biomass and only these gas mixtures are directly burnt at high oxygenconditions compared to the systems above in which solid fuels were directly burnt. Duringpyrolysis, since only gases with less carbon content are direly burnt, the solid content left has a higher organic carbon content and is called biochar.

Pyrolytic combustion, or pyrolysis, heats biomass in an environment with limited oxygen conditions. The technique has been used in thousands of years, mainly in the industries. The ”181126 Application teXt.201811260309066679 180038SE pyrolytic combustion produces pyrolytic gases, volatile substances from the fuel that takesfire and will be combusted to produce heat until all volatile substances have been com-busted. At last also the solid residue will be combusted. The residue from the pyrolytic com-bustion in cooking fires using biomass is biochar. The biochar can in turn be used in different ways. ln pyrolytic combustion, it is possible to use fuels that are less favorable in traditional com-bustion. For example, biomass having a lower energy content, such as straw, reed and dungcan be used in pyrolytic combustion. This is because it is the gas that is incinerated, andproblems related to combustion of solid fuels, such as emission of toxic substances and particles can thus be avoided.

There are several problems with the existing biochar cookstoves. One problem is that thecookstoves operates in batches, meaning that when the chamber is out of fuel it is not pos-sible to cook anymore until the ashes have been removed, new fuel inserted, and combus-tion starts again. Both the input of biomass and removal of biochar can only be done asdiscontinuous for these cases. This takes time and the stove, and the pots used for cookingor boiling water, will be cold before the cookstove can be used again. Another problem isthat existing cookstoves working with pyrolysis demand a preconditioned or pretreated bi-omass such that moisture content fall within 8 to 20%. This is necessary to achieve pyrolysisand not only combustion. lf the moisture content falls outside this range problems such aslots of smoke and huge presence of carbon monoxides in smoke occurs when the fuel is ignited.

Further example of problem is that most of the existing biomass cookstoves are not energyefficient, they only supply energy to specific and small needs and sometimes could not evenboil water before one batch of feedstock is finished. They are commonly constructed vvithtvvo concentric cylindrical containers, vvnere the inner cylinder is the fuel pot. The fuel potis provided with holes in the base, vvhich serves as the primary air inlet. The ftiel pot is alsoprovided with holes on the neck, servlng as a secondary air iniet. The outer cylinder is pro~vided vtfitli hoies riear the bottom on the sldes. During cornhustlori, air enters these iioies, either by natural air tiraft or forced vtfltli a DC fan dependlng on requirement and ”181126 Application text.201811260309066679 180038SE construction rhodel. The user fälls the fuel pot with fuel, just below the secondary air inletholes and ignites the top layer of fuel for the pyroh/sis to start. Air then flows in through theprimary and seeoimlary air ihlets. The primary ihlet helps the draft ef pg/reiyzeci vvetvd gas“flew tipwards. This is called a top-lit updraft gasifier. Cooking furnaces liite this have forexarhple been described in CN 103742946, CN fiíšitüäíššêš, CN lfiéi-üütšllíš, CN 2tï=432906§and CN 107238109.

The present invention solves the above-mentioned problems by providing a cookstove thatcan be used continuously and therefore also is more energy efficient. The cookstove pre- sented can be used as a part of a system as a strategy for sustainable emission reduction Hence, the invention relates to a device for combustion of a combustible material, whichdevice comprises at least one inner wall and at least one outer wall, creating a double wallspace in between, which double wall space is provided with at least one primary air inlet,and a top wall having at least one top opening. The device further comprises an inclinedtubular means; which tubular means further comprises an inlet for the combustible mate-rial in the upper part, a pyrolytic chamber located on the inside ofthe inner wall of thetubular means, an outlet in the lower part of the inclined tubular means, and an outletcover. The double wall space comprises a secondary air distribution zone for distribution of hot air and facilitating mixing of pyrolytic gases; a combustion zone; and a flame zone.

The tubular means is preferably inclined with an angle of 30 i 15 degrees from a horizon- tal line.

The device can further be provided with a thermocouple zone comprising at least onethermoelectric generator to convert heat into electrical power. The outer wall can further be provided with a heat insulator.

The device is preferably provided with a stand, which stand can further comprise an elec- tric charging control unit and at least one electric charging outlet port. ”181126 Application teXt.201811260309066679 180038SE The invention further relates to a method for using biological material wherein biologicalmaterial is combusted in the device and biochar is thereafter collected. The biological ma- terial is preferably a biomass.

The method can further comprise one or more ofthe following steps: - Use of energy from the combustion for cooking food in a pot placed in the potholder; - Producing electricity by utilizing at least one thermoelectric generator; - Using the biochar for water filtering and/or processing the biocha r. This biochar canfurther be used as a fertilizer in soil.

The method is preferably a continuous method for production of heat. ln the following, the invention will be described in detail, with reference to exemplifying embodiments ofthe invention and to the enclosed drawings, in which: Fig. 1A shows a perspective view of an outer shell of one embodiment of a device for pyro-lytic combustion of biomass Fig. 1B shows a vertical cross-sectional view of an upper part of the device Fig. 2 shows a view of one of the short sides of the device for pyrolytic combustion of bio-mass Fig. 3 shows a view ofthe other short side ofthe device for pyrolytic combustion of biomassFig. 4A shows a cross sectional side view of a device for pyrolytic combustion of biomassFig. 5 shows a block chart of a method for using a biological material Fig. 6 shows a block chart of a life cycle achieved by using the device in the method Referring to Figs. 1-4 a device according to the present invention suitably comprises at leastone inner wall and at least one outer wall, creating a double wall space in between, whichdouble wall space is provided with at least one primary air inlet. lt further comprises a topwall having at least one top opening, an inclined tubular means; which tubular means fur-ther comprises an inlet for the combustible material in the upper part ofthe inclined tubular means, an inlet cover, a pyrolytic chamber located on the inside of the inner wall 3 of the ”181126 Application teXt.201811260309066679 180038SE tubular means for combustion of biological material, an outlet in the lower part of the in-clined tubular means and an outlet cover. The double wall space comprises a secondary airdistribution zone for distribution of hot air and facilitating mixing of pyrolytic gases, a com-bustion zone and a flame zone 12. At least one of the inner walls comprises through holes (opening) to let hot air flow into the secondary air distribution zone.

Fig. 1A shows a first embodiment of the device for pyrolytic combustion of a combustiblematerial, preferably biomass, wherein the device 1 comprises an inclined tubular means 2,which device 1 is provided with inner walls 3, outer walls 4, which has a tubular outer wall4A and planar outer walls 4B, and a top wall 17. The device 1 can further be provided witha stand 16. The inner wall 3 and the outer wall 4 create a double wall space 15 arrangedbetween said inner wall 3 and outer wall 4. The double wall space 15 follows the shape ofthe substantially circular inclined tubular means 2 in the lower part of the device andthereafter forms a space above a pyrolytic chamber 6 comprising three different zones; asecondary air distribution zone 9, having through holes as openings 13, between the innerwall 3 and the outer wall 4, a combustion zone 11 and a flame zone 12. These are de- scribed more in detail with reference to figure 4.

The inclined tubular means 2 is preferably an essentially circular tubular means but could also be a rectangular tubular means.

The double wall space is provided with at least one primary air inlet 8 on one of the shortsides of the tubular means 2, where air at ambient temperature enters the device. The atleast one primary air inlet 8 is preferably provided in the lower end of the inclined tubularmeans 2 and has an elongated shape to more effectively let air into the double wall space.ln the embodiment shown in figure 1A, six elongated inlets 8 are provided. lt is howeverpossible to have either more or fewer inlets. The number of inlets is preferably adapted to the size of the tubular means 2.

The tubular means 2 further comprises an inlet 5, in one end of the device. The inlet 5 isprovided with a cover 51, which can be opened for insertion of fuel, i.e. a combustible ma- terial, in the upper part of the inclined tubular means. The inlet 5 is preferably provided on ”181126 Application teXt.201811260309066679 180038SE the short side in the upper part of the tubular means 2. After insertion of the combustiblematerial, the inlet 5 is closed so that no air enters the chamber through the inlet to let thepyrolytic combustion take place. The inlet will only be opened later in the process to addmore fuel, if necessary. The inlet 5 can also be used to control the flame, hence heat with little effect to quality of biochar within this scale of production.

Combustible material can for example be pellets, wood, sawdust or wood dust (a byproductor waste from woodworking), rice straw (agricultural byproduct consisting of the dry stalksof rice crop, after the grain has been removed), dry dung (animal waste that has been driedin order to be used as a fuel source), biomass briquettes (a biofuel substitute mostly madeof green waste and other organic materials), or any other fuel suitable for use in a pyrolyticchamber. ln this description, the combustible material will be called ”biomass”, but the per-son skilled in the art understands that also other types of combustible material can be used in the device 1.

A pyrolytic chamber 6, for combustion of the biomass, is located inside of the inner wall 3ofthe tubular means. The pyrolytic chamber will be described more in detail with refer- ence to Figs.1B and 4. ln an end opposite to the inlet 5 there is an outlet 7, where the byproduct can be re-moved. The outlet is preferably provided in the lower part of the inclined tubular meanstogether with the at least one primary air inlet. The location of the outlet in the lower endofthe inclined tubular means facilitates removal of the byproduct more easily. lt couldalso be possible to remove byproduct from an outlet provided on the side of the pyrolyticchamber (not shown). The outlet 7 is provided with an outlet cover 71, which can beopened for discharge or removal of the byproduct from the chamber 6. ln this embodi-ment the cover 71 is an outlet disc but can be any type of cover that can be opened andclosed and that prevents air from coming into the chamber when it is in a closed position.The cover 71 is preferably provided with a handle 72. This is described in more detail with reference to Fig. 3 below.

The device is also provided with a top opening 10 above the flame zone 12. The top open- ing 10 can in turn preferably be provided with at least one pot holder 14. The embodiment ”181126 Application teXt.201811260309066679 180038SE shown in figure 1A is provided with a pot holder 14 comprising three parts 14A, 14B and14C, but also other types of pot holders can be used as is understood by a person skilled inthe art, comprising more or lesser parts. lt is also possible to provide the device 1 withmore than one top opening 10 and more than one pot holder 14. The pot holder is pro- vided for holding a pot for cooking food or boiling water.

The device 1 is further provided with a stand 16, which stand is further described with ref- erence to fig. 4 below.

Fig. 1B shows a vertical cross-sectional view of an upper part of the device 1, showing thetubular means 2, an inner wall 3, an outer wall 4, the pyrolytic chamber 6, the double wall space 15, the primary air inlet(s) 8, a top wall 17 having a top opening 10.

The inner wall 3 comprises a tubular inner wall 3A and a planar upper inner wall 3B. The planar upper inner wall 3B comprises openings 13 to the secondary air distribution zone.

The secondary air distribution zone 9 brings hot air from the pyrolytic chamber 6 throughthe openings 13 and into a combustion zone 11. This is described in more detail below with reference to Fig.4.

The pyrolytic chamber 6 is inclined by approx. 30 degrees from a horizontal plane. The in-clination can be varied within i 15 degrees but has shown best effect for pyrolytic combus-tion with an inclination of 30 i9 degrees. The circular tubular shape of the pyrolytic cham-ber, , has proven most effective for the pyrolytic combustion of the material to take place.lt is possible to increase the length of the chamber 6 (and the rest of the device 1) to addmore top openings 10 and/or pot holders 14 to the top of device 1. The space of the pyro-lytic chamber is defined by the inner walls 3A and 3B, the inlet 5, the outlet 7 and the topwall 17. ln the lower part the inner wall is curved (3A) and in the upper part it is in an uprightplanar position (3B). The top wall 17 of the device 1 is provided with a top opening 10 towhich the pot holder 14 can be attached, and a pot placed for example for cooking food or heating water.

Fig. 2 shows one short side of the device 2, comprising an inlet 5, which inlet is provided with a cover 51. ln this embodiment the cover 51 is a rotatable inlet disc but can be any ”181126 Application teXt.201811260309066679 180038SE type of opening that can be opened to let biomass in and the closed to prevent air fromentering the pyrolytic chamber 6. The cover 51 is preferably provided with a handle 52. Thehandle can be any handle that can be used to open the cover 51 but is preferably of a ma-terial that will not be too warm when the device is in use. ln the case where the cover 51 isan inlet disc, the handle will be used to rotate the disc into a position where an openingappears in the outer wall. The inlet disc can be rotated by pushing the handle 52 so thatthere is an opening in the outer wall 4 and fuel, biomass, can be fed into the chamber 6.After the material has been inserted, the inlet disc is rotated in the reversed direction so that the inlet is closed, and no air can enter the chamber.

Fig. 3 shows the other short side of the device 2, comprising an outlet 7, which outlet isprovided with a cover 71. ln this embodiment the cover 71 is an outlet disc 71 and is pro-vided with a handle 72. The handle can be any handle that can be used to open the cover71 but is preferably of a material that will not be too warm when the device is in use. ln thecase where the cover 71 is an outlet disc, the handle will be used to rotate the disc into aposition where an opening appears in the outer wall. The outlet disc 71 can be rotated bypushing the handle 72 so that there is an opening in the wall 4. When the outlet is open,the byproduct from the pyrolysis can be removed through the outlet 7 and the cover, oroutlet disc, is then closed again. The outer wall 4A of the short side of the device 1 shown in Fig. 3 is also provided with primary air inlets 8, as described above.

Figure 4 shows a cross-sectional side view of the device 1, showing the inclined pyrolyticchamber 6 provided with an inlet 5 and an outlet 7. Above the pyrolytic chamber, threedifferent zones are located; a secondary air distribution zone 9, having through holes 13,between the inner wall 3 and the outer wall 4, a combustion zone 11 and a flame zone 12.Figure 4 shows one half of the device 1, meaning that the other half of the device 1 is pref-erably also provided with the same three zones. The secondary air distribution zone 9 bringshot air from the chamber through the openings 13, which openings are an array ofthroughholes, and into a combustion zone 11. The through holes 13 are provided on at least oneinner wall 3, more preferably on two opposing inner walls along the length of the tubularmeans 2. The through holes 13 are preferably provided in an inclination to a horizontal plane. The inclined array of through holes 13 leads to a turbulent flow of hot air which ”181126 Application teXt.201811260309066679 180038SE facilitates the mixing of pyrolytic gases at the combustion zone. The inclination of theseholes 13 are preferably parallel to the combustion chamber 6 and it is possible to vary theangles by 30 +/- 15 degrees to a horizontal plane. The array of through holes can also be provided in a zig-zag form. ln the combustion zone 11, the pyrolytic gases and the hot air from the double wall spacewill be mixed by turbulence that is created by the inclined arrangement of the holes andthe pressure difference it creates. The flame zone 12, which is close to the top opening and the pot holder, will provide the heat needed to cook food or heat needed inside a boiler. ln the flame zone 12, the pyrolytic gases will be burned completely or optimally due to thepresence of a high amount of oxygen molecules at the surroundings of the turbulent flowof initially ignited gases from the combustion zone. lt is important to note that the flamesare initially generated when starting the system by firing a quantity of biomass. The sameflames are improved thereafter to firing gases which moves towards a region with high and expandable oxygen molecules in concept. This is observed as flame zone by user.

The device 1 can further be provided with a thermoelectric generator zone 18. A thermoe»lectric generator procluces a temperature-»dependent voltage as a result ofthe thermoelectric effect, i.e. the temperature difference between the inside of the deviceand the air outside of the device can be converted into electric voltage due to the thermo-electric effect The thermoelectric generator zone 18 preferably comprises a thermoelectricgenerator such as a Peltier element, (one example is TEC1-127, but it could be any suitablegenerator) which converts the heat into electrical power of 4 to 12volts. Although the ther-moelectric generator zone has been shown in this embodiment to be on a specific place of the device 1, the location ofthis can be varied.

Thermoelectrical generators are used to produce electrical power enough to power electri-cal light bulbs of nominal wattages ranging from 5 to 25 watts at direct low voltages usingthe See beck-effect. The pyrolytic temperature of the stove ranges from 300°C up to a max-imum of 500°C, such that some of the heat from the pyrolytic chamber is used to speed up the motion of air molecules in the combustion zone, making the temperature drop to an ”181126 Application teXt.201811260309066679 180038SE interval of 100°C to 200°C. A heat insulator, such as for example a ceramic insulator, mineralwool insulator, etc can be provided on the outer wall to reduce the heat of the surface to a range of 50°C to 65°C.

The device 1 is further preferably provided with a stand 16 (shown in Figs. 1A, 2, 3 and 4).Besides holding the device 1, the stand 16 can also be provided with an electric chargingcontrol unit 19 and at least one electric charging outlet port 20, such as for example USB-ports, for charging electrical equipment such as for example cell phones and light bulb con-nectors. The electric charging control unit 19 can for example be electric power regulatorsin combination with storage batteries. This unit 19 regulates, stores and supplies the powerat low voltages to the at least one charging outlet ports 20. The control unit 19 and the atleast one outlet port 20 can also be placed located on other parts ofthe stand 16. The deviceis preferably provided with more than one outlet port 20. lt is possible to have several dif-ferent outlet ports, such as for example one or two USB-ports and one or two light bulbconnectors. A person skilled in the art understands that the type of ports can be varied and that also other types of outlet ports can be provided. ln this way, it is possible to use some ofthe heat generated during the pyrolysis in the device 1 for charging electrical equipment.

The device 1 described are preferably used in a method for combustion of biomass. The method is further described below.

To operate the device 1, the cover 51 is opened so that biomass can be inserted into thepyrolytic chamber 6 through the inlet 5. The cover 51 is then closed. Since the pyrolyticchamber is inclined, the inserted biomass moves downwards towards the outlet 6, which isinitially closed. The outlet covers 71 is opened and a flame from for example a gas lighter ora match stick is used to ignite the biomass. As mentioned above, also other sources for ignition of biomass can be used. The cover 71 is then closed completely.

To ensure that the system lights up completely from the beginning, the cover 71 can be left open for about 1-2 minutes. lt is also recommended to use easily flammable materials as ”181126 Application text.201811260309066679 180038SE 11 the first charge of biomass inserted into the pyrolytic Chamber to help overcome the acti- vation energy for pyrolysis.

To achieve pyrolytic combustion instead of normal combustion, pyrolytic conditions mustbe defined; i.e. burning in a controlled/limited amount of oxygen. To start the process, bio-mass is first fed into through the in|et 5 to the pyrolytic chamber 6. The biomass is ignited,either manually or by any other means that can be used to ignite fuel. During the first partof the process, direct burning of the initial material will take place, which leads to energyand a small amount of ash. During this latent or lag phase ofthe process, it can be observedan instant small quantity of smoke which dies down within 1-2 minutes when pyrolysis grad- ually takes over and stabilizes to produce pyrolytic combustible gases (mainly methane).

The combustion generates external energy into the pyrolytic chamber, this energy is neces-sary to start the pyrolytic process. The starting energy is then used to overcome energybarrier needed in intermediary processes (biomass drying, torrefaction, depolymerization)that usually occurs before pyrolysis. This is simply achieved by letting small quantity of bio- mass first undergo normal combustion for a short while.

After this first combustion, where energy needed to overcome the energy barrier needed iscreated, pyrolytic combustion, or pyrolysis, takes place in the pyrolytic chamber. This pyro-lytic combustion acquires enough energy to cause bond breaking and therefore atoms arefree to mix and forms combustible gases. These combustible gases expand as continuouslyheated (as per Brownian motion), the direction of motion is towards a comburant attraction(oxygen) upwards to the secondary air distribution zone 9 and the combustion zone 11. Thezones typically overlap each other, but each playing an interdependent role. The easier theremoval and burning of these gases, the higher the efficiency of the pyrolysis in the cham-ber. To achieve this, air at normal temperature is let into the double wall space throughopenings 8, that is linked to the pyrolytic chamber 6, following a temperature gradient.There is always air trapped in the double wall space 15. When pyrolysis is going on, the airin the double wall space 15 gets heated and must expand (Brownian motion). This air is thenattracted towards the combustible gases. The inclined tubular means 2 contributes to achieve a turbulent flow. The gases produced in the pyrolytic chamber 6 rises towards the ”181126 Application text.201811260309066679 180038SE 12 combustion zone 11 with a stronger affinity for an upward draft due to the presence ofoxygen from the hot secondary air distribution zone 9. This air, once entered through pri-mary air in|et 8, was trapped in the double wall space 15, between the inner wall 3 and theouter wall 4 and is constantly heated by the heat from the pyro|ytic chamber. The heatincreases the velocity of the air which forces air molecules to move faster compared to pri-mary air. The higher the temperature of the pyro|ytic chamber 6, the higher the speed ofthis hot air which creates a difference in pressure between the volume of air in the doublewall space 15 and the air surrounding the device 1. This difference in air pressure forcescold air from outside into double wall space 15, through the at least one primary air in|et 8,creating the draft necessary for the combustion (the Bernoulli principle). The hot secondaryair at high speed will then mix with the pyro|ytic gases ignited by the initial flame which then expands more at the flame zone giving heat for cooking.

During this time, the possibility for air to flow directly into the pyro|ytic chamber 6 is verylow as the only way for air to enter the pyro|ytic chamber is through the outlet 7 and thein|et 5. The in|et 5 is during the process commanded by the draft (affinity of some gaseswanting to leave through this in|et to meet with oxygen) and since the pressure from insideis greater than air pressure from outside, the possibility of air going inside this is only whenno heat inside, therefor limited. Since on the other side of the chamber 6, the outlet 7 is closed, then pyrolysis can be achieved.

The demand of energy is mainly based on the food being cooked. lf cooking is going on,subsequent or series of biomass can be injected following the same feeding process de- scribed above, but no relighting is needed which facilitates the continuous supply of heat.

Fire accelerants can be used if found necessary, such as paper, starter cubes etc. to ignite the feed stock, especially of the feed stock is damp.

The flame, in the flame zone 12 can be adjusted by opening or closing the in|et and/or outletdiscs. Opening of a disc will create a higher flame and closing of a disc will cause the flame to be lower. ”181126 Application teXt.201811260309066679 180038SE 13 The biochar produced, which is removed from the device 1 by opening the outlet cover 71,can be removed in series as well as accumulated and removed after cooking. Biochar re-moved after cooking, when the device 1 is cooling down is more stable and has a higherquality as biochar. The biochar is preferably removed into any metallic vessel and quenched with cold water completely.

The device 1 and the process described above has shown to reduce smoke level with up to85% as compared to traditional cookstoves. lt is also easier to use because various biomasssources can be used as feedstock. Further, there is no need for blowing on the fire once started, which saves time.

The method according to the present invention, which is shown as a block chart in figure5, therefore comprises at least the steps of- combustion of biomass in a device 1 as described above; and - collecting biochar from the device 1.

The energy, in form of heat, produced during the combustion can then be used for cook-ing food, boiling water or the like. Some ofthe heat can also be used for producing elec- tricity by utilizing at least one thermoelectric generator.

The byproduct, biochar can be removed from the chamber either after the combustion isfinished and the system has cooled down, or it can be removed from the outlet 6 beforecooling while the device is still in use. The safest way of removing the biochar is when thepyrolytic chamber is almost full of the byproduct. This is also more time saving than remov-ing subsequently. However, it is also possible to remove biochar continuously by openingthe outlet 7 and using a tool for displacement of the hot biochar out ofthe chamber 6. Thebiochar can then be placed in a container with water. However, biocharthat is simply placedin a container with water affects the quality of biochar negatively because it does not leadto enough porosity of biochar. A better way of cooling the biochar is therefore to use waterjets, either inside (in the case of removal at the end of cooking) or outside (if removal is done during use of the device) to cool down the biochar. ”181126 Application teXt.201811260309066679 180038SE 14 Biochar of good quality can then be used further for filtering water or the biochar can beprocessed and used as a biochar fertilizer in soil. Biochar that is used for filtering water can in turn be used as biochar fertilizer in soil afterwards.

The method according to the present invention gives an entire life cycle, as shown in Figure6. Where leftovers from food can be used as fuel in pyrolytic combustion. The pyrolyticcombustion in turn produces energy for cooking food, electricity for charging electricalequipment. The heat from the cookstove will also heat up the room where it is standing anddry biomass that is placed in that room. The byproduct, biochar, can be used for filteringwater or processed to be a biochar fertilizer. The biochar fertilizer is placed in the soil to-gether with seed to plant new seeds. Carbon dioxide in the air and the photosynthesis willprovide new crops that in turn can be harvested and used for food. Where the leftovers canbe used in the pyrolytic combustion. This model is then suitable as means for sustainableemission reduction as well as clean development mechanism accounting for direct emissionreductions through smoke reduction compared to traditional inefficient systems and carbonstorage. lt also contributes to indirect emission reduction by increasing the capacity ofgrowing more plants when biochar improves the soils, enhancing capture through photo- synthesis.

Above, an exemplifying preferred embodiment has been described. However, it is realized that the invention can be varied without departing from the basic idea of the invention.

Hence, the invention is not to be considered limited to the above described embodiments but may be varied within the scope of the enclosed claims. ”181126 Application teXt.201811260309066679 180038SE

Claims (17)

1. A device (1) for combustion of a combustible material, comprising:-inner walls (3) and outer walls (4), creating a double wall space (15) in between, whichdouble wall space is provided with at least one primary air inlet (8);- a top wall (17) having at least one top opening (10);- an inclined tubular means (2); which tubular means (2) further comprisesan inlet (5) for the combustible material in the upper part of the inclined tubularmeans (2);an inlet cover (51);a pyrolytic chamber (6) located on the inside of the inner wall (3) ofthe tubularmeans;an outlet (7) in the lower part ofthe inclined tubular means; andan outlet cover (72);and wherein the double wall space (15) comprises a secondary air distribution zone (9) fordistribution of hot air and facilitating mixing of pyrolytic gases; a combustion zone (11);and a flame zone (12);and wherein at least one of the inner walls (3) comprises through holes (13) to let hot air flow into the secondary air distribution zone (9).

2. A device according to claim 1, characterized in that the inclination of the inclined tubu- lar means (2) is 30 i 15 degrees from a horizontal plane.

3. A device according to claim 1 or 2, characterized in that the through holes (13) are pref- erably provided in an inclination to a horizontal plane.

4. A device according to claim 1,2 or 3, characterized in that the device further comprisesa thermoelectric generation zone (18) having at least one thermoelectric generator to convert heat into electrical power.

5. A device according to any of claims 1-4, characterized in that the device further com- prises a stand (16). ”181126 Application teXt.201811260309066679 180038SE 16

6. A device according to any of claims 1-5, characterized in that the stand (16) comprises an electric charging control unit (19) and at least one electric charging outlet port (20).

7. A device according to any of claims 1-6, characterized in that the outer wall (4) com- prises a heat insulator.

8. A device according to any of the preceding claims, characterized in that the top wall (17) is provided with at least two flame zones and at least two top openings.

9. A device according to any of the preceding claims, characterized in that the combustible material is a biomass.

10. A device according to any of the preceding claim, characterized in that the at least onetop opening is further provided with at least one pot holder for holding a pot for cooking food or boiling water.

11. A method for using biological material comprising at least the steps of - combustion of a biological material in a device according to any of claims 1-10 - collecting biochar from the device.

12. A method according to any of claim 11, characterized in that the biological material is a biomass.

13. A method according to claim 11 or 12 further comprising the step of - using energy from the combustion for cooking food in a pot placed in the pot holder (14).

14. A method according to claim 11, 12 or 13, further comprising a step of producing elec- tricity by utilizing at least one thermoelectric generator.

15. A method according to any of claims 11-14, further comprising a step of using the bio- char for water filtering and/or processing the biocha r. ”181126 Application teXt.201811260309066679 180038SE 17

16. Method according to claim 15, wherein the processed biochar is used as a fertilizer in soil.

17. A method according to any of claim 11-16, wherein the method is a continuous method for production of heat. ”181126 Application teXt.201811260309066679 180038SE