Combustion burner - combustion chamber

Technical field

The present invention deals with an engineering device - burner, combined with a fuel line and electronic controller, which enables automatic operation of the entire assembly. The burner is designed to obtain energy by burning solid fuels, biomass mainly wooden pellets, vegetable materials and grain.

Background Art

Biomass combustion is one of progressive ways of replacing standard fuels (fossil) by alternative sources. Huge development is taking place in this area in these directions:

Fuel development (materials, from which the fuel is prepared)

- Combustion mechanism development (mainly burners)

Current technological processes are attempting to use burners of classical construction derived from grates (movable or immovable), alternatively with active aeration, etc.

The present invention deals in the area of combustion mechanism development

Disclosure of the invention

The present invention operates on a different principle using several new elements.

Combustion chamber in cylindrical shape with perforated walls, alternatively in blunted cone shape with perforated walls: where this shape has the following characteristics:

a) Easy access of air to fuel during the combustion process b) continuous automatic fuel line and ash removal c) flawless burner operation even when burning fuel with low ash fusing point

Combustion chamber in cylindrical or blunted cone shape enables the possibility of rotation in the cylindrical axis during the combustions, what causes continuous mixing and aerating of fuel thus enabling complete burning.

The present invention serves mainly for heating f detached houses and premises with energy outputs between 8kW to 2MW, which can be even greater provided some further changes are made.

Burner, resp.the entire assembly (including fuel line and electronic controller) may obligatory be used in solid fuel furnaces. The burner itself is designed so that it can replace the entire combustion units in commonly used solid fuel furnaces by a majority of manufacturers.

The uses of burner in furnace of local manufacturers, equipped with a flange to which the burner can be mounted have been tested. With furnaces where the mounting of burners is different the assembly needs to be adjusted with respect to specific conditions of the construction. Furthermore, the connection of the burner and furnace needs to be subject to testing in national test centre.

In tested furnaces the flange is located on both left and right-hand side so that it is possible to adjust the functionality of the burner with respect to local conditions. The mounting of the burning takes place in the following steps :

dismount the original combustion units. The furnace is equipped with two flanges - one flange is blinded, the second is equipped with the original burner. Remove the burner from the flange, in which it is mounted. (Adjustment of differently designed furnace before the mounting of new burner. The burner is mounted to a flange which is built on the furnace) - remove the cover of the flange on the furnace (right or

left-hand side according to the particular installation) , blind the other flange by a cover and screw the burner according to the present invention. The adjustment takes approximately 20 minutes, final stage of mounting of the new burner for biomass combustion: screwed burner is accompanied by an additional fuel worm and fuel holder, then it plugs into 220 V. the rated power appropriate for heating premises is then set on burner electronics

The burner burns biomass in the form of pellets from various materials (energetic plants, straw, industrial hemp, grain residues etc.), wooden pellets, crushed coal, grain corn etc.

The burner itself is accompanied by fuel line mechanism and electronic controller which ensures the automatic operation of the entire system.

Individual components of the system are as follows:

Fuel (pellets from biomass from various sources. Similar rushed material) is stored in a container of appropriate shape, mostly blunted cuboids or pyramid placed upside down. This shape guarantees that the fuel moves downwards by its own weight to the lowest point of the container, through which the fuel worm passes.

The container can e made of various materials preferably from steel plate with 1 mm thickness with corrosion protection. The requested shape is obtained by welding individual walls. Commonly sold containers can also be used. The container is separated from the furnace by rotting valve, which is a part of the burner for safety reasons. Therefore, the fuel cannot ignite in the fuel worm and consequently in the fuel container. For the safety reasons the container has to be placed at least 1 m from the furnace.

The fuel conveyer a pipe with circular cross-section, in which there is the fuel worm. See fuel worm attachment. Standard fuel conveyer provided by local manufacturers can also e used. In longer lines the pneumatic conveyer is used. The length of the conveyer is theoretically not limited however in practice it is possible to work with length of up to 5m. The top part of the pipe is open in the part where the pipe passes through the bottom of the container. Therefore the fuel falls into the conveyer and the fuel worm delivers it to heat-resistant combustion chamber.

Some conveyers comprise a withdrawable leg, which is adjusted according to the position of the furnace with the burner so that the fuel is directed in a horizontal direction. With other types of conveyers the horizontal fuel feed is provided in another way according to local installation conditions.

The conveyer ends in proximity of furnace and enters into a short vertical pipe through which the fuel falls into the fuel worm already a part of the furnace. The vertical pipe is equipped with _^ vane sensor and rotating valve.

Electronic operating: a board with intelligent display equipped with two microprocessors, set of optotriacs for fan operation with feedback, main engine, ignition nozzles, fuel worm, and furnace pump is located on the burner. It further comprises the entrance gates for reading of photo chamber (fire-non-fire), terminal drum switch for checking of the burner pipe angle when igniting, sensor of vane fuel sensor, furnace thermo regulator, interactive control using a keyboard and display (there are approximately 20 programmable variables, which are located in EEPROM permanent memory) . The board also comprises a code (unauthorized access). The control board also registers real-time clock.

The burner - heat-resistant combustion chamber (rotating) according to this invention comprises.

Outside housing of the burner which has two functions: first, it fixes the combustion chamber in functional setting and maintains cooling of the upper part of the burner by the air from the fan. The air enters the combustion chamber; it is preheated and thus increases the burning efficiency. The outside housing is a two layer chamber in the shape of hollow cuboid with square base made of standard metal plate with 3mm thickness. The core of the housing is the main frame, to which the plates of the bottom plate are affixed. The upper part is turbo chamber and the lower part is the air chamber, these two being connected by six screws. Thus the turbo chamber covers the combustion chamber from top and lateral side and air chamber from bottom and lateral sides. The main axis of the cuboids is in horizontal position, both square bases forming ends of the housing. There are circular holes in both ends equally spaced between the turbo chamber and air chamber. The fuel conveyer enters trough one hole and open end of the combustion chamber leaves the other hole. With cylindrical chamber the main axis of the housing is parallel to the axis of the combustion chamber.

The outside housing is formed by covering metal plates. Their main function is to increase the safety of burner operation (they do not allow strange objects to enter into the proximity of the burner) .

Horizontal fuel worm leads into the outside housing. Its function is to direct the fuel into the burner. The pipe of the fuel worm is not close at the entrance, thus the fuel is pushed out directly into the combustion chamber. Due to the circular cross section of the chamber the flow is simple - the combustion chamber is coaxial (or nearly coaxial) continuation of the fuel worm pipe. Fuel worm is on its other side

connected to fuel conveyer using a vertical hose with vane sensor and rotation valve (tourniquet).

Vane sensor indicates the presence of the fuel in entrance pipe. When there is no more fuel, the vane sensor informs the controlling board which then starts on a specific time the fuel worm leading from the container to the vertical pipe. Rotational valve is a device which prevents back burning of fuel into the fuel pipe and then through the conveyer into the container. At the same time it supplies the fuel into the burner.

The hole through which the conveyer enters the outside housing must be equipped with a flange used to mount the burner into the furnace. This flange is partially a part of the furnace but partially it is necessary to adjust it according to the burner. The flange of the burner sits on this flange thus forming the back part of the combustion chamber. The fuel worm also leads into this flange as well as the igniting nozzle, blocker and frame with two carbon bearings.

The combustion chamber is made of grey cast iron. It is in a shape of cylinder jacket (pipe) partially coaxially inserted into the outside housing. There are holes along the entire surface of the pipe. In the outside housing the combustion chamber rotates on carbon heat resistant lubricous bearings around its axis (main axis of the cylinder) , which is also the axis of the outside housing. He fuel worm leads into one base of the cylinder (hidden inside the outside housing) . The division between the combustion chamber and the fuel conveyer is fitted with a sealing element with carbon heat-resistant bearing. The fuel thus enters the combustion chamber without the risk of falling between the mouth of the conveyer and the entrance hole.

The second base of the cylinder (located outside the outside

housing) is missing. Gas and solid exhaust and remains (ash) leave through this hole.

The igniting nozzle leads into end of the combustion chamber together with the conveyer. The nozzle is a heating spiral accompanied by a small fan with own bimetal protection.

Standard radial fan is used. This fan is controlled by the central controller in 250 levels of ventilation. For each type of fuel, each chimney and each burner has a different ventilation level (the amount of oxygen) . For each operation mode (ignition, full operation and slowing down the operation) a different variable, which determines he exact amount of oxygen directed into the combustion chamber, is assigned. The fan is also used to cool the back part of the burner, feeding worm, carbon bearing and igniting nozzle.

The entire assembly is driven by a single electromotor with power supply of 220 V and output of 0,25 kW and worm clutch. Aeration and cooling is provided by the fan with energy output of 8OW. The igniting nozzle used to ignite the burner has the output off 2kW. Vane sensor with output of 2W is used to detect the amount of fuel. The entire burner is operated and controlled by a controlling board with 2,5W. The electromotor using mechanical transmission supplies the following system functions .

Rotation of the combustion chamber inside the housing (rotation frequency and length is programmable, because each type f fuel requires different parameters). It is possible to set the angle of pipe and interval of rotation of the final engine round with a clutch to approximately lrround per 4,5s.

- Rotation of the feed worm inside the conveyer. Engine rounds of about 1 round per 4,5s. Feed worm rotates in one direction and the pipe rotates in the other direction once the engine is switched on.

Cylindrical combustion chamber

Current technological processes are attempting to use burners of classical construction derived from grates (movable or immovable), alternatively with active aeration, etc. The present burner for biomass combustion has instead of a flat grate a cylindrical perforated combustion chamber, which rotates during the operation in preset intervals. Thus the fuel which is supplied by the fuel worm mixes with burning fuel, frequently changing its position and is completely aerated by preheated air which is supplied by the turbo chamber. New fuel is thus quickly ignited and the old fuel participates for several minutes on the burning process. It turns several times, completely aerates in the entire volume and always completely burns. The old fuel is subject to full heating and sufficient air flow with temperature of 1000-1200 degrees Celsius even several minutes after it completely burns out. This ensures complete burning of all burnable elements in hundred percent of the fuel volume and using the full efficiency of the burning heat. This effect can be seen also on emission analyzers, the measured efficiency of the entire burning assembly is around 95%.

The chamber is made of cast iron (wall thickness 25 to 35 mm) allowing automatic cooling of the outside wall during the rotation. Using other materials would lead to melting or other damage of the chamber.

The air enters the pipe so that it first flows around the outside of the pipe, thus heating itself and then it is driven through the bottom hole into the combustion area. This procedure ensures higher level of heat energy efficiency produced by the burner.

Exact supply of the fuel with electronic regulation:

Electronic controller allows exact supply of the fuel into the combustion chamber. It minimizes the volume of unburnt remains, what has a positive impact on emission levels, burner efficiency and fuel spectrum that can be used. The fuel is distributed through the rotation valve. The fuel worm is now used only to deliver the fuel into the combustion chamber. The gases that enter the fuel worm during the combustion are separated from the ambient air by a rotation valve.

Possibility to use less combustible materials

Current burners are rather sensitive to the fuel used mainly to its dampness and amount of remains, i.e. ashes when burning. The present burner due to perfect aeration and accurate fuel supply allows the use of material with high sintering capacity (e.g. Grain straw pellets). Sintering is given by low melting point, what is a problem almost of all alternative pellets including peat pellets. Only pellets from white wood (which are expensive) do nit sinter. When burning the pellets silter and wrap with other fuel and ashes. Thus the siltering leads to clogging of the grate a bad burning (inside siltered pieces the temperature is not high enough). All current burners designed for wooden pellets suffer from this drawback. The pipe of the present invention can burn even materials with high siltering thus ensuring the complete burning.

Low emission levels

The functionally, mainly the amount of emission they produce is very important hen burning solid fuels. High burning temperature (up to 1200 degrees Celsius) which is maintained due to perfect burning on the rotation chamber, results in very low emission levels (e.g. with grain pellets PPM 12-20 micrograms/m3 with the limit of 2000micrograms/m3)

High level of burning efficiency and low waste

When burning in the chamber the temperature reaches very high levels, which lead to almost 100% efficiency, i.e. there are only virtually unburnable substances left in the ash. Furthermore the energy for heating is maximal zed. (The exact percentage of remaining ash depends on the features of the fuel) .

Description of drawings

Figure 1 -burner assembly for combustion according to the present inventions

Figure 2 - combustion process according to the present invention

Figure 3 - cross section of the combustion burner according to the present invention

Preferred embodiment

The outside housing is in the shape of a cuboid with sguare base located so that the main cuboid axis is in horizontal position. The dimensions are 800 x 40 x 60 mm. The housing is double coated, made of steel plate with thickness of 3 mm. Both square bases are ends (right and left) of the cuboid. There are circular holes with a diameter of 200 mm in both ends of the cuboid. The fuel conveyer enters the outside housing through the right hole while the open end of the combustion chamber extends from the left end.

The combustion chamber is made of grey cast iron. It is in a shape of cylindrical jacket (pipe) partially coaxially inserted into the outside housing. The cylinder dimensions are (base diameter x height) 200x400 mm, wall thickness of 20 mm. There are holes with 4 mm diameter with 25x25 mm spacing along the entire surface of the pipe. In the outside housing the combustion chamber rotates on carbon heat resistant lubricous bearings around its axis (main axis of the cylinder) , which is

also the axis of the outside housing. The fuel conveyer leads into one base of the cylinder (hidden inside the outside housing) . The entrance of the conveyer has a diameter of 70 mm. The division between the combustion chamber and the fuel conveyer is fitted with a sealing element with carbon heat- resistant bearing. The second base of the cylinder (located outside the outside housing) is missing. Gas and solid exhaust and remains (ash) leave through this hole.

The igniting nozzle leads into end of the combustion chamber together with the conveyer. The nozzle is a heating spiral with an output of 2kW accompanied by a small fan with own bimetal protection.

Standard radial fan with output f 8OW and programmable rotation is used (rotation range 100-3000rotation/min) for

Various types of fuel, chimney and furnace. The fan also serves to cool the back part of the burner, fuel worm and igniting nozzle.

The system is equipped with a vane sensor with input of 2W, which is placed in the conveyer before the entrance into the combustion chamber. The entire burner is maintained and controlled by the controlling board with input of 2,5 W.

The entire assembly is driven by a single electromotor with power supply of 220 V and output of 0,25 kW and worm clutch. The electromotor using mechanical transmission supplies the following system functions.

- Rotation of the combustion chamber inside the housing it is possible to set electronically the angle of pipe and interval of rotation of the final engine round with a clutch to approximately lround per 4,5s.

- Rotation of the feed worm inside the conveyer. Feed worm rotates in one direction and the pipe rotates in the other direction once the engine is switched on.

System works n the standard mode in the following way:

Ignition:

Burner 14 electronics in calm state expects the command of the main thermo regulator (e.g. Room thermo regulator) that the low level has been reached, what serves a signal to switch the system into the working mode. Once the electronics accepts this signal it checks with the vane sensor 7 the presence of fuel in the feed worm; If the fuel is not present in the feed worm the conveyer is starting until the vane sensor signals the presence of fuel in the worm. The worm 12 following further order of the controller feeds into the combustion chamber and starts a fan 6. Te igniting nozzle 4 is then ignited. After about two or three minutes the controlling electronics increases the rpm and commences the full operation.

Full operation:

Approximately every 30 seconds (fixed interval) the worm 12 feeds fuel into the combustion chamber. The combustion chamber 1 slowly rotates thus ensuring equal and complete burning of the fuel maintaining high temperature (1000-1200 degrees Celsius). This mode lasts until the entire area is heated what is indicated by the main thermo regulator which signals reaching of the high temperature.

End of operation.

One the controlling unit receives the signal from the thermo regulator is issues a command to stop the periodic feed of fuel by the worm 17, command to increase the rotation of the combustion chamber during a preset interval (approximately 10-

15 minutes) and to simultaneously cool the chamber by fan. Once this time elapses the chamber is sufficiently cool to switch into the calm state, in which it remains until new command that the low temperature level was reached is detected. Once this command is detected the systems switches into the ignition stage again.

Further examples if the present invention

A) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment but they differ in size. With respect to the size the values of energy output/input also change (fan, electromotor, etc.)

B) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment except for the combustion chamber which is not cuboid but slightly conical (blunted cone jacket) . As a result the holes in the ends are not of the same size.

C) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment except for the combustion chamber which is not an even cuboid it has a different shape in its central part between the mouth of the conveyer and the fitting. The combustion chamber can be for example on the outside surface of the cooling rib or other protrusion.

D) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment. However the combustion chamber is not located exactly coaxially with the main axis of the outside housing. The chamber axis leans towards the open end.

E) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment except for the housing which has different shape from that of cuboid - e.g. it can be cylinder with greater diameter than the diameter of the combustion chamber, prism with other than square base, the shape can be altered by e.g. installation elements suitable for different furnaces, etc .

F) The entire assembly functions in an identical way, all components are of the same shapes and made of identical materials as the preferred embodiment except for the holes of the combustion chamber which has different shape and spacing - it need not to e only circular holes, but also for example axial slots or holes of a different shape made during the casting or other processing.

Advantages of the present invention

The fuel burns in cylindrical rotational combustion chamber. The main advantages of this type of burning are:

- Very efficient burning

- complete burning of the fuel

- very low emissions of carbon dioxide when burning. Less than 50 micrograms per m3

- fully automatic operation (controlled by room thermo regulator)

- good combustibility (without clogging) of materials with low as fusion point (e.g. straw)

- low purchase price (68 thousand CZK) of the burner

- very efficient elements for securing the safety of the burner used

- burner economy of 0,3 CZK/kWh (many times lower that electricity or gas)

- due to burning efficiency it is much more economical that solid fuel furnaces

The quality of burning can be easily seen on the flame from the burner. Electronics containing two independent processors allows specific setting for various fuels so that the burning is always economical with the lowest emissions.

The burner is designed so that the ignition starts very quickly (usually up to two minutes) and end of operation and automatic cleaning takes place without unnecessary emissions.

Industrial utilization

The present invention can e used to heat houses and premises with energy output between 8 and 50 kW. The burner must be used with solid fuel furnace eventually with a different heat exchanger. It mainly burns solid fuels, biomass in the form of pellets (energetic plants, straw, industrial hemp, grain waste etc., wooden pellets but also crushed coal, grain, corn, etc.

List of components

1- Heat resistant combustion chamber (rotational)

2- Turbo chamber

3- Heat resistant bearings

4- sealing barrier with heat resistant bearings

5- igniting nozzle

6- fan

7- fuel sensor

8- fuel line

9- engine

10- clutch

11- rotational valve

12- fuel worm

13- combustion chamber drive

14- controlling computer

15- fuel worm drive

16- flexible hose for fuel line (16), feed worm

17- feed worm