TITLE: PELLET BURNER AND A METHOD OF OPERATING
FIELD OF INVENTION:
The present invention is related to a unique designed industrial pellet burner and a method of operating the pellet burner. The said pellet burner is fully automatic which is PLC driven and embedded with self ignition mechanism. Pellet burner design is compact and can easily fit to gas and oil fired heat systems to generate heat. The said pellet burner operates on variety of fuel pellets made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue of various size (up to 10 mm dia & 50 mm length) with ash percentage up to 20 wt %. Operating process includes mechanically controlled pellet feeding, controlled air circulation arrangement to increase efficiency and controlled ash removal mechanism. The burner is designed in this manner so as to maintain the same efficiency or heat output as achieved from oil/gas burners.
BACKGROUND OF INVENTION:
Fuel pellets have now a days become more popular as an alternative fuel to fossil fuel to generate heat and power. They are made from compressed biomass. Pelletization technology has become well advanced and almost all kinds of biomass are pelletized and converted in to fuel pellets like; wood, wood residue, forest left over, grasses, saw dust, agricultural residue, agri-processing industry waste, coal powder, municipal solid waste etc. Fuels produced by pelletization are very dense and possess low moisture content (less than 10 %) which allows it to burn with a very high combustion efficiency. Moreover during pelletization biomass is made in regular geometry and small size so that it can be easily fed in the burner with very fine calibration in order to produce constant heat. High density of fuel pellets can be easily stored in compact storage such as bunker and silo, it is also convenient for its transport over long distance. Fuel pellets are manufactured in several types and grades such as fuels for thermal power plants, commercial and domestic applications like cooking and heating.

With the advent of latest engineering tools, devices in form of pellet stoves, pellets burners and pellet boilers it has become easy to use biomass fuel pellets for heat and light as an alternative to fossil fuel. A pellet burner is a specific engineering device to burn compact pellet fuel to produce low emissions, provide convenient and easily controllable heating.
Pellet burner is compact and uniquely designed engineering device which can fit to various gas and oil based systems to generate heat and they have certain advantage over the traditional wood burning devices like; reduced emission and greater heat exchange capacity. These leads to a great interest in producing an efficient pellet burner. Unique air supply with continuous feed of fuel pellets and ash removal mechanism enhance productivity and applicability in various applications. There have been some engineering attempts to design efficient pellets based burner with various designs.
WO1998031968A1 patent disclose a method for controlling the supply of air to a burner designed on wood chips and pellets. The invention focused on supply of primary air into an inner burner tube through openings in the tube wall, said inner burner tube forming a combustion chamber for the gasification of the fuel, and whereby secondary air for the combustion of the formed gases are supplied through a space formed between the inner burner tube and an outer burner tube and through a secondary air opening formed in the region of free ends of the inner and outer burner tubes, whereby the temperature by the combustion of the formed gases is detected continuously and the supply of primary and secondary air is controlled proportionally, directly depending upon the detected temperature, characterized in that the control of the supply of primary and secondary air is performed through relative displacement of the inner and outer burner tubes and the resulting change of the flow area of the secondary opening and at least one of the primary air openings.
While WO2007139475 Al patent disclose a burner for all pellets such as bio-pellets with specific engineering arrangement like , comprising a chute having a longitudinal axis, the

chute having a generally horizontally oriented longitudinal axis and having an inner wall of an essentially cup-shapedly upwardly open cross-section shape, a feeding device for feeding a bed of the particulate matter in and along the chute, and a device for supply of primary air to the bed in the chute, the primary air supply device being arranged to, without contact, direct primary air from above toward the free topside of the bed in the chute, characterized in that the supply device has one or more primary air outlet openings that along a substantial portion of the length of the chute direct primary air downward close by the inside of each one of the upper edge parts of the chute.
WO 01/23808 Al patent disclose a pellet fuel burner with cooking grill, fire box with open top plane. In which pellet feeding device opens into the fire box and is disposed to feed pellets into the burner unit. A pressure box has an inlet supplied with combustion air at a positive pressure. A plurality of outlets are provided in the pressure box and disposed so as to create turbulent combustion air flow in the pellet burner unit. Invention is designed to particulate fuel pellet made from corn kernels.
EP0760922B1 The present invention related to a tubular burner for solid fuel (pellets) and is intended for mounting in boiler furnace, the forward portion of the burner being insertable through an opening in the furnace casing such as to extended into the combustion zone of the furnace.
All above mention invention face major challenges in handling various types & quality of fuel, efficient air circulation which leads to increase in heat exchange efficiency with efficient fuel consumption, reduced hazardous emissions, flexibility to fuel coupled with gas and oil fired boilers. Present invention relates to pellet burner which can over come challenges as mentioned above. The said pellet burner is a device to burn all types of fuel pellets to genrate heat and which can be easily coupled with oil and gas fired heat systems like low pressure steam boiler, hot water generators, furnace, ovens, dryers etc and to generate heat for large residential, commercial and industrial spaces. Designed pellet burneer are compatible to pellets size up to 10 mm diameter & 50 mm lenght and ash up to 20 %. Controlled, automatic

feeding of pellets from pellet hopper to a combustion chamber and controlled air supply from blower will mechanise the flame length as per the physical requirment.
SUMMARY OF THE PRESENT INVENTION
The present invention relates to a unique industrial pellet burner and a method of operating the pellet burner. Available pellet burner has one or more technical problem like; fuel types, adaptability to fuel types, efficient air circulation, heat exchange efficiency, efficient fuel consumption, emissions, long operation and flexibility to fuel coupled with gas and oil fired boilers. The main object of the present invention is to provide versatile types of fuel pellet consuming industrial pellet burner with unique method of primary air supply under the ash grate for uniform air distribution in combustion chamber. The said pellet burner is a device to burn all types of fuel pellets to generate heat and which can be easily coupled with oil and gas fired heat systems like low pressure steam boiler, hot water generators, furnace, ovens, dryers etc and to generate heat for large residential, commercial and industrial spaces. The said burner is fully automatic, PLC driven and self ignited pellet burner that can easily fit to gas and oil fired heat systems to generate heat. It also operates on variety of fuel pellets made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue of various size (up to 10 mm dia & 50 mm length) and ash percentage up to 20 wt %. Said invention has mechanically controlled pellet feeding, controlled air circulation arrangement to increase efficiency and motorized ash removal mechanism. Controlled, automatic feeding of pellets from pellet hopper to a combustion chamber and controlled air supply from blower will provide and option to mechanize the flame length as per the physical requirement. It is designed to maintain same efficiency or heat output inline with similar capacity of oil/gas fired burners.
The pellet burner is well ergonomic structure assembly with C shaped base frame mounted with square shaped double walled combustion chamber, pellet hopper with holding capacity of 35 kg pellets, air supply mechanism, ash handling system and PLC with all electric parts

like HMI, PLC, MCB, SMPS, relay, connectors, VFD. Main pellet silo with fuel holding capacity of 275 kg is provided separately with auger types fuel transfer mechanism. Said industrial pellet burner has air curtain provision at pellet feeding point towards combustion chamber which nullifies the back fire or back smoke effects and operates with efficient heat exchange capacity.

Number Element Figure
1 Material silo 1,2
2 Pellet feeding 1,2
3 Castor wheel silo 1,2
4 Fuel feeder 1 1,2
5 Hopper feeding motor 1,2
6 Fuel Discharge pipe 1,2
7 Hopper 1
8 Feeding screw motor 1,2
9 Feeding pipe 1,2
10 Linear actuator 1,2
11 Combustion chamber 1,2
12 Hinge 1,2
13 Top cover 1,2
14 Fire view glass 1
15 Fire door 1
16 Fire/flame outlet 1,2
17 Flame 1
18 Ash door 1
19 Castor wheel of burner 1,2
20 Base frame 1,2
21 Blower 1
22 Blower motor 1.2
23 Control panel 1
24 Hopper inside view 2
25 Combustion chamber inside view 2
26 Refractory 2
27 Fire tube 2
28 Ash chamber 2
29 Moving top grate 2
30 Fix middle grate 2
31 Bottom moving grate 2
Figure 1 shows the burner for pellets according to the invention, seen at a front view
Figure 2 shows a cross -sectional side view of the burner for pellets according to the invention.

In accordance with a preferred embodiment of the invention as shown in the top perspective view in FIG. 1, a pellet burner includes material silo 1 with pellet feeding 2 from top and having castor wheel 3 for movement pellets are fed to hopper 7 by screw type fuel feeder-1 4 and fuel discharge pipe-2 6 operate by hopper feeding motor 5, feeding screw motor 8 moves pellets through feeding pipe 9, linear actuator 10 helps in great movement in combustion chamber 11, top cover 13 of combustion chamber 11 attached with hinge 12 for flexible opening, fire view glass 14, fire door 15, fire/flame outlet 16 and flame 17, below combustion chamber 11 there is an ash door 18. Whole combustion chamber 11 is setup on base frame 20 with castor wheel 19, blower 21 is run through blower motor 22 and supply air to combustion chamber 11, all electric parts are controlled by control panel 23. The FIG. 2 is a cross -sectional side view of the pellet burner shows material silo 1, pellet feeding 2, castor wheel 3, fuel feeder-1 4, hopper feeding motor 5, fuel discharge pipe-2 6, feeding screw motor 8, feeding pipe 9, linear actuator 10, combustion chamber 11, hinge 12, top cover 13, fire outlet 16, castor wheel 19, base frame 20 and blower motor 22, in addition to these hopper inside view 24, internal view of combustion chamber 25, refractory 26, fire tube 27, ash box 28, moving top grate 29, fix middle grate 30 and bottom moving grate 31 are clearly shown. The control panel 23 as shown in FIG. 1 consist main electric cord to connect with mains 220 Volts. Other electronic/electrical components are assembled in control panel like human machine interface system (HMI), programmable logic controller (PLC), miniature circuit breaker (MCB), switch mode power supply (SMPS), relay, conductor, variable frequency drive (VFD). The control panel 23 having proportional-integral-derivative controller (PID) which controls fuel feed and air supply to combustion chamber 11 as per define program, it will evaluate the actual values with set value for temperature/pressure and accordingly control the fuel feeding and air supply.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a unique industrial pellet burner and a method of operating the pellet burner. The present invention provides fully automatic, PLC driven and self ignited pellet burner that can easily fit to gas and oil fired heat systems to generate heat. The said pellet burner operates on variety of fuel pellets made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue of various size ( up to 10 mm dia & 50 mm length) and ash percentage up to 20 wt %. Said invention has mechanically controlled pellet feeding, controlled air circulation arrangement to increase efficiency and motorized ash removal mechanism. It is designed to maintain same efficiency or heat output inline with similar capacity oil/gas fired burners. In accordance with a preferred embodiment of the invention pellet burner with features as mentioned above is described herein. The structure G assembly contain C shaped base frame 20 which has 04 nos heavy duty wheels 19 for smooth movement of burner. Base frame 20 is a basic structure made from iron to carry load of all components of burner. Combustion chamber 11 is in square shaped mounted on base frame 20 in which pellet fuel from hopper 7 and air from blower 21 are fed and partly gasification cum combustion take place and generates volatile gases. Hot volatile gases start coming out from combustion chamber 11 via fire outlet tube 16 mounted on combustion chamber 11. Secondary air is also discharged at fire outlet tube 16, secondary air get mixed with hot volatile gas and produces sharp ash free flame 17 and discharge from combustion chamber 11 by fire outlet tube 16 via fire tube 27. Combustion chamber 11 has top cover 13 with hinge attachment 12 for chamber cleaning, fire view glass 14 to view the inside of the chamber, fire door 15 for clinker and grate cleaning, ash door 18 for ash cleaning. There is refractory 26 wall inside the chamber 11 to retain heat inside and minimize heat radiation loss. Other components of burner are fuel feeding system, meant for pellet fuel feeding from storage silo 1 to the burner combustion chamber 11 which consists of pellet/material silo 1 for storage of pellet fuel, fuel feeder pipe -1 4 for feeding fuel from silo to hopper, hopper feeding motor 5,

fuel discharge pipe 6, burner hopper 7, feeding screw motor 8 and feeder pipe 9. There is an air feeding system, meant for primary and secondary air supply in combustion chamber for proper combustion of fuel which consists of air blower 21, motor 22 and air ducts with dampers for manual controlling of air supply. Grate system meant for holding fuel, mixing of fuel and air then intermediate discharge oi ash from grate to ash chamber which consists o£ moving top sliding 29, fix grate 30, bottom moving grate 31 and linear actuator 10. There is one control panel 23, having feather touch color HMI, PLC control for control and monitoring of all operations of burner.
Combustion Chamber : Combustion chamber 11 is square shaped double shell structure having refractory 26 brick linings inside 25 to retain heat inside the chamber and minimize heat radiation loss. Double shell is designed for circulation of secondary air which provides additional insulation and passive cooling to combustion chamber. There is fuel feeding system connected to chamber meant for pellet fuel feeding from storage silo 1 to the burner combustion chamber 11. There is air feeding system, meant for primary and secondary air supply through blower 21 in combustion chamber 11 for proper combustion of fuel. Grate system meant for holding fuel, mixing of fuel and air then intermediate discharge of ash from grate to ash chamber. This three grate system consists of two sliding 29, 31 and one fix grate 30 with slots for primary air supply from bottom which continuously moving the fuel, ash and drain the ash at end of bottom sliding grate 31.
Fuel feeding system ; Other critical system of burner is fuel feeding system, meant for pellet fuel feeding from storage silo 1 to the burner combustion chamber 11. Pellet fuel is filled in the storage silo 1 by manually at pellet feeding 2, from which pellet fuel is conveyed to burner hopper 7 through screw feeder (fuel feeder -1 4 and fuel discharge 6), screw feeder operate with hopper feeding motor 5, then fuel will be further conveyed to combustion chamber 11 through screw fuel feeder in feeding pipe 9. Pellet silo 1 is designed for storage of about 275

kg fuel and burner hopper 7 is designed to fill about 35 kg pellets. This system consists of pellet silo 1 for storage of pellet fuel, fuel feeder pipe 4 for feeding fuel from silo to hopper, gear motor 5, fuel discharge pipe 6, burner hopper 7, feeding screw motor 8 and feeder pipe 9.
Air supply system : Air supply system meant for primary and secondary air supply in combustion chamber 11 for proper combustion of fuel. High speed air blower 21 is used to blow the air inside the system which directs through air duct for primary/secondary air supply and control through dampers. Primary air is supplied to bottom of grate for proper combustion and secondary air will travel through double shell and out at flame outlet for 100% burning of volatile matters. This system is consists of air blower 21, blower motor 22 and air ducts with dampers for manual controlling of air supply.
Operation of the present invention;
Pellet fuel is filled in the storage silo 1 at pellet feeding 2, from which pellet fuel is conveyed to burner hopper 7 through screw feeder (fuel feeder -1 4), then fuel will be further conveyed to combustion chamber 11 through screw fuel feeder via feeding pipe 9. This burner is operated in auto mode with PLC based control panel 23. When start it in auto mode, first process is to feed the sufficient amount of pellet in the combustion chamber 11 from hopper 7 for first ignition and same time electric heaters are ON. After predefined time, blower will start and hot air injected on fuel to start burning oi fuel. As the fuel catch the flame inside the chamber 11, flame sensor detect the flame and give signal to PLC to start the fuel feeding. Fuel feeding system is continuous feeding and control by drive and PLC as per fuel requirement. At desired temperature/pressure, accordingly PLC will operate burner with control feeding of fuel and air. Control primary and secondary air volume by setting dampers manually. Provision of three grate system inside the chamber 25, consists of 2 sliding and 1 fix grate with slots for primary air supply from bottom which continuously moving the fuel, ash

and drain the ash/clinker at end of bottom of sliding grate 31 to ash chamber 28. There is one motorized ash removal screw which continuously take out the ash/clinker outside of chamber from ash box. This intermediate ash/clinker removal is facilitating no fouling/slagging on heat transfer area of heating system, as combustion ash is remain on grate and only heat/hot air is going in to the system.
To stop the burner, first stop the hopper gate and then press stop button on control panel 23. It will stop fuel feeding but blower 21 and grate system will run up to predefined time to cool down the chamber and cleaning of grate from ash/clinker. When it cools down, open fire door 15 and clean the ash/clinker from grate and inside the chamber. Burner is ready for next operation. To use the equipment continuously, it has been equipped with a unique sliding grate mechanism to remove the ash/clinker intermittently. The feature enables the continuous operation by removing the ash content during the operation which otherwise need to be removed when accumulated.
Electronic part:
An electrical cord is provided to connect the Industrial burner control panel 23 to mains 220 V, single phase supply. There are various electronic/electrical components like HMI, PLC, MCB, SMPS, relay, connectors, VFD etc inside the control panel. It has PID control and controls fuel feed and air supply to the combustion chamber as per system requirement. It will evaluate the actual values with set value for temperature/pressure and accordingly control the fuel feeding and air supply.

WE CLAIM:
1. A solid biofuel particularly pellet fired burner comprising,
a. a burner structure with fuel pellet silo and pellet hopper
b. a fuel feeding mechanism with fine control and autoignition
c. a pellet hopper with an upper opening for feeding pellet
d. an upright pellet hopper with pellet transferring mechanism to the combustion
chamber to allow insertion of pellets in the combustion chamber
e. a square shaped combustion chamber
f. an integrated circulation of primary and secondary air
g. a unique design with operational safety with leakage proof insulation, complete fuel
combustion, smokeless & ash less flame, easy plug-in and plug-out system with
existing heating system, pellet hopper with a constricted opening at the base for
controlled flow of pellet from hopper, with two sliding and one fixed grate system
with linear actuator for holding fuel, mixing of fuel with air and intermediate
discharge of ash to ash chamber, motorized ash removal screw to take out ash/clinker
outside of chamber from ash box
h. a control panel with PID based controls for fuel feed, air supply, self ignition and ash removal system.
2. The burner according to claim 1, combustion chamber is square shaped suitable for
gasification cum combustion of such fuels therein, double shell with refractory insulation, having a floor portion for receiving noncombustible residue.
3. The burner according to claim 1, a fuel feed auger oriented in a manner such that said
auger is angled upwardly from said lower end portion of material silo to said hopper bin. A hopper bin for said fuel pellets positioned outside near to combustion chamber and having a conveyor screw at lower end positioned for transferring fuel to said combustion chamber.
4. The burner according to claim 3 where in primary air is supplied to bottom of grate which
provides uniform air supply to enhance combustion of fuel and secondary air is passed
through double shell and exit at flame outlet and enhances burning of volatile matters.

5. The burner according to claim 1 where in combustion air is supplied through high speed
air blower and direct through air duct for primary and secondary air supply and control through dampers.
6. The burner according to claim 1, burner setup and design is constructed for combustion
of all types of pellet as fuel source where in said pellet having an ash content up to 20 % wt with length up to 50 mm and diameter up to 10 mm.
7. The burner according to claim 1, wherein heater positioned inside combustion chamber
towards lower end with PLC based controlled to autoignition of fuel pellets.
8. The burner according to claim 1, wherein a grate system of burner oriented with linear
actuator positioned bellow the pellet hopper with three grate, top and bottom are sliding grate and middle fixed grate to remove the ash/clinker intermittently.
9. The burner according to claim 1, where in burner component mounted on C shaped base
frame with heavy duty castor wheels for desire movement of whole assembly.
10. A self ignited solid biofuel fired pellet burner as herein described with reference to
foregoing drawings.