TITLE: A PELLET BURNER APPARATUS AND METHOD OF OPERATING
FIELD OF INVENTION:
The present invention relates to an innovative commercial 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, diesel 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 6-8 mm dia & 20-30 mm length) and ash percentage (up to 10 wt %). Operating process contains mechanically controlled pellet feeding, controlled air circulation arrangement to increase efficiency and controlled ash removal mechanism. It has been designed this way to maintain its efficiency or heat output when compared to oil/gas/diesel burners.
BACKGROUND OF INVENTION:
Fuel pellets have now a days become more popular as an alternative 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 at 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 which 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.
In 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-shaped 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 front 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 mentioned inventions are facing major challenges in handling various types and quality of pelleted fuels, efficient air circulation which leads to increase in heat exchange efficiency with efficient fuel consumption, reduction in 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 present invention, a 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.

Designed pellet burners are compatible to pellets size up to 10 mm diameter & 20-30 mm length and ash up to 10 %. Controlled, automatic feeding of pellets from pellet hopper to a combustion chamber and controlled air supply from blower will mechanize the flame length as per the physical requirement.
SUMMARY OF THE PRESENT INVENTION
The present invention relates to a unique pellet burner apparatus and a method of operating the pellet burner. Available pellet burners in prior art has one or more technical problem like; fuel types, adaptability to different fuel, air circulation, heat exchange efficiency, efficient fuel consumption, emissions, long operation, flexibility to fuel coupled with gas and oil fired boilers etc. The main object of the present invention is to provide versatile types of fuel pellet consuming smart pellet burner apparatus which can resolve all above mention problem associated with similar types of invention existing in prior art.
The said pellet burner apparatus is a device to burn all types of fuel pellets to generate heat and which can be easily fit to oil, gas and diesel 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 oil, gas and diesel fired heat systems to generate heat. Present pellet burner apparatus operates on variety of fuel pellets made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue of various size (up to 6 -8 mm dia & 20-30 mm length) and ash percentage up to 10 wt %. The said pellet burner apparatus is fully PLC driven; it has mechanically controlled pellet feeding, controlled air circulation arrangement to increase efficiency.
The pellet burner is well ergonomic structure assembly with compact air box, combustion chamber, pellet hopper with holding capacity of 35 kg, ash handling system and PLC. Further the present unique industrial pellet burner apparatus consists of Hopper, Hopper flange, hopper coupling, fuel feeding mechanism (feeder pipe, feeder screw), grate system (pipe for

moving grate, first grate, second grate and third grate), electric cylinder 60 mm stroke, Cylinder mounting plate, screw feeder motor, blower with duct, air box, base plate, pipe for secondary air supply, refractory dome, dome cover, primary air box, inclined air box (flame guide), heater and electric connector mounting plate, air box cover and PLC including HMI, PLC, MCB, SMPS, relay, connectors, VFD.
A BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 Front view illustrating pellet burner apparatus.

Fig. 2 Cross - sectional view pellet burner apparatus.
Fig. 3 Isometric View of pellet burner apparatus.

Figure 1 Shows the pellets burner apparatus according to the invention seen at a front view
Figure 2 Shows a cross -sectional side view of pellets burner apparatus according to the invention.
Figure 3 Shows isometric view of pellet burner apparatus according to the invention

Numbers Element Figure
1 Fuel Hopper 1,2,3
2 Fuel Hopper Flange 1,2,3
3 Fuel Hopper Coupling 1,2,3
4 Fuel Feeder Pipe 2,3
5 Fuel Feeder Screw 1,2,3
6 First Grate 2,3
7 Second Grate 2,3
8 Third Grate 2,3
9 Pipe for Moving Grate 2
10 Electric Cylinder 60 mm Stroke 2
11 Cylinder Mounting Plate 2
12 Feeder Screw Motor 2
13 Blower 1,2
14 Blower Duct 2
15 Air box 2
16 Base Plate 1,2,3
17 Secondary air pipe 1,2,3
18 Refractory dome 2,3
19 Dome cover 2,3
20 Primary Air box 1,2,3
21 Inclined air box(FJame Guide) 1,2,3
22 Heater 2,3
23 Electric connector Mounting Plate 1,
24 Air Box Cover 2

In accordance with a preferred embodiment of the invention as shown in the top perspective view in FIG. 1, a pellet burner apparatus includes fuel hopper 1 with fuel hopper flange 2, fuel hopper flange 2 is connected with fuel hopper coupling 3, base plate 16 with fuel feeder screw 5, primary air box 20, inclined air box (flame guide), secondary air pipe 17, electric connector mounting plate 23 and blower 13. The FIG. 2 is a cross -sectional side view of the pellet burner apparatus shows fuel hopper 1 with fuel hopper flange 2, fuel hopper flange 2 is connected with fuel hopper coupling 3, fuel feeder pipe 4, fuel feeder screw 5, first grate 6, second grate 7, third grate 8, pipe for moving grate 9, electric cylinder 60 mm stroke 10, cylinder mounting plate 11, screw feeder motor 12, blower 13, blower duct 14, air box 15, base plate 16, secondary air pipe 17, refractory dome 18, dome cover 19, primary air box 20, incline air box (flame guide) 21, heater 22 and air box cover 24. The Fig. 3 is the isometric view of the a pellet burner apparatus shows fuel hopper 1, fuel hopper flange 2, fuel hopper coupling 3, fuel feeder pipe 4, fuel feeder screw 5, first grate 6, second grate 7, third grate 8, base plate 16, secondary air pipe 17, refractory dome 18, dome cover 19, primary air box 20, inclined air box (flame guide) 21 and heater 22.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a unique pellet burner apparatus and a method of operating the apparatus. The said invention describe fully automatic, PLC driven and self ignited compact good looking well engineered pelleted fuel operated apparatus that can easily fit to gas, diesel 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, agro processing waste, biomass processing waste and all industrial or commercial pelleted fuel. The size of the said pelleted fuel could be up to 8 mm dia & 30 mm length with ash percentage up to 10 % of weight. Said pellet burner apparatus has controlled pellet feeding mechanism, controlled air circulation arrangement to increase efficiency and

motorized ash removal mechanism through moving and fix grate system. It is designed to produce equal efficiency for long time to supply constant heat output as in case of other oil, gas and diesel fired burners. In accordance with a preferred embodiment of the invention pellet burner apparatus with features as mentioned above is described herein. The pellet burner apparatus mainly contain fuel hopper with transfer mechanism of pelleted fuel to combustion chamber further it include fuel hopper 1, hopper flange 2, hopper coupling 3, fuel feeder pipe 4, fuel feeder screw. The fuel system of burner apparatus is connected with air box 15 covered with air box cover 24 and blower 13 to maintain air fuel ratio. The component where pellet fuel burn is refractory dome 18 covered by dome cover 19 which is connected with fuel feeding system and air box 15 by base plate 16. The refractory dome contain first grate 6, second grate 7 and third grate 8, out of first grate 6 and third grate 8 are moving by pipe for moving grate 9. All these component are integrated in to compact structure to develop said pellet burner apparatus and further linked with control panel with PLC and HMI for fine control. Pelleted fuel made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue, agro processing waste, biomass processing waste and all industrial or commercial pelleted fuel with 6-8 mm dia, 20 -30 mm length with ash percentage up to 10 % of wt are filled -up in fuel hopper 1, at a time 35 kg of pelleted fuel can be filled-up. Fuel pellets through gravity force enter into fuel feeder pipe 4 which is connected with fuel hopper 1 by hopper coupling 3 and hopper flange 2 and through fuel feeder screw 5 fuel pellets enteres in the combustion zone where electric heaters 22 are fitted for auto ignition, partial gasification cum combustion take place in refractory dome 18. Refractory dome 18 is covered with dome cover 19 and one fix grate as second grate 7 on above moving first grate 6 and below moving third grate 8, moving grates are connected with moving pipe 9. After proper heating blower 13 is automatically switched on as per programme and air is blown through blower duct 14, air circulation is maintained by air box 15, secondary air enters form secondary air pipe 17, secondary air helps in complete combustion of pelleted fuel and flame is guided through inclined air box 21. Pelletd fuel get burn in refractory dome 18. Grate

system is meant for holding fuel, mixing of fuel and air then intermediate discharge of ash from moving grate.
Fuel Combustion: Combustion of pellet fuel takes place in refractory dome 18, refractory dome 18 is covered by refractory dome cover 19. Lower surface of refractory dome 18 is covered with grate system containing two moving grates (first grate 6 and third grate 8) and one fix grate 7. Grate system helps in holding the fuel pellets, mixing of fuel pellets and air then intermediate discharge of ash from refractory dome 18. From front side refractory dome is covered with inclined air box 21 which acts as flame guide. Pelleted fuel of 6-8 mm diameter, 30 mm length with ash percentage up to 10 wt % enters in refractory dome from back side where heater 22 is placed, fuel pellets heated by heater 22 and as per program, blower starts circulating air and fuel catches fire. Air circulation is controlled by air box 15, blower 13 speed and air fuel ratio is maintained by primary air box 20 and secondary air through secondary air pipe 17. Efficient air circulation system contribute complete combustion of pelleted fuel from various biomass particularly wood waste, agricultural residue, agro processing waste.
Fuel feeding system: Fuel feeding system is important part of any heat generating apparatus , in present invention fuel pellet made from wood, wood residue, forest left over, grasses, saw-dust, agricultural residue, agro processing waste, biomass processing waste and all industrial or commercial pelleted fuel with 6-8 mm dia, 20-30 mm length with ash percentage up to 10 wt % are used and fuel enters in the combustion dome/refractory dome 18 from fuel hopper 1. Fuel pellet is filled in the fuel hopper 1 manually, from which pellet fuel travels to fuel feeder screw 5 from fuel feeder pipe 4 by gravity force. Fuel feeder screw 5 operates with feeding motor 12 controlled through PLC, which regulates fuel feeding and hence the flame intensity. Then fuel pellets will be further conveyed to refractory dome 18 where heater 22 is set for preheating of fuel pellets. After sufficient time for fuel heating blowers 13 start and fuel pellets catches fire.

Air supply system: Air supply system meant for primary and secondary air supply in refractory dome 18 for proper combustion of fuel pellets. High speed air blower 13 is used to blow the air inside the system which directs through air box 15 and primary air box 20. From blower duct 14 air is distributed as primary and secondary air and managed by primary air box 20 and secondary air pipe 17 and enters in the refractory dome 18, blower speed is maintained by PLC which is further linked with fuel feeding system which maintains efficient air-fuel ratio in refractory dome 18 and enhance complete combustion of fuel pellets. Primary air is supplied to bottom of grate for proper combustion and secondary air through secondary air pipe 17 at fuel pellet outlet from fuel feeder screw 5.
Electronic part:
An electrical cord is provided to connect the pellet burner apparatus control panel to mains 220 V, single phase supply. There are various electronic/electrical components like HMI, PLC, MCB, SMPS, relay, connectors, motor, etc configured on electric connector mounting plate 23. It has PID control which controls fuel feed and air supply for efficient fuel combustion.
Operation of the present invention:
The present invention is related to a fuel pellet based apparatus and method of operating the same to achieve high efficiency of fuel use and decrease the undesirable emissions. The said apparatus burner comprises of; Base plate 16 structure and mounting frame 23, refractory dome 18 with dome cover 19, Three Grate system moving first grate 6, fixed second grate 7 and moving third grate 9 with ash removal mechanism, fuel hopper 1, fuel feeding system with screw fuel feeder 5 with gear motor 12, Blower 13 for air, air circulation system with airbox 15, primary air box 20, secondary air pipe 17 and PLC & HMI based control panel.
The fuel pellet hopper 1 is filled with fuel pellet made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue, agro processing waste, biomass processing waste

and all industrial or commercial pelleted fuel with 6-8 mm dia, 20-30 mm length with ash percentage up to 10 wt %, through fuel feeder pipe 4 fuel pellets come in contact to fuel feeder screw 5. This burner apparatus is operated in auto mode with PLC based control panel. When the burner is started in auto mode, first process is to feed the sufficient amount of pellets in the chamber for ignition and after that electric heater 22 is switched ON and after 3 minutes the blower 13 is switched ON. At a predefined time, heater 22 will be switched OFF. As the fuel pellets catches the flame inside the refractory dome 18, flame sensor detect the flame and give signal to PLC to start the fuel feeding. Fuel feeding system is ON/OFF cycle based feeding and control by PLC as per requirement of fuel. Control of primary and secondary air volume is maintained by blower speed. Provision for moving and fix grate system is for proper mixing of fuel, for its complete combustion and to remove intermediate ash/clinker and facilitating no fouling/slagging on heat transfer area of heating system. To stop the burner, first the stopper of hopper is closed to stop fuel feeding, and then after predefined time stop button on panel is pressed. It will stop fuel feeding and other operation but blower will run up to predefined time to cool down the refractory. When it cools down, the burner is removed from system / equipment for cleaning the ash or slag from grate and bottom ash compartment.

WE CLAIM:
1. A pellet fired burner apparatus comprising,
a. an upright pellet hopper with pellet transferring mechanism to the refractory dome
to allow insertion of pellets in the refractory dome
b. a fuel feeding mechanism with fine control and auto-ignition
c. two moving and one fixed grate system
d. an integrated circulation of primary and secondary air
e. a unique compact design with full operational safety, with leakage proof
insulation, complete fuel combustion, smokeless & ash less flame, easy plug-in and
plug-out system with existing heating system, fuel pellet hopper with a
constricted opening at the base for controlled flow of pellets from the hopper, with
two sliding and one fixed grate system,
f. a control panel with PID based controls for fuel feed, air supply, self ignition and
ash removal system.
2. The pellet burner apparatus according to claim 1, where in combustion takes place in
refractory dome which is semicircular shaped suitable for gasification cum combustion of fuel
pellets therein, refractory dome is covered and having a floor portion for receiving
noncombustible residue.
3. The pellet burner apparatus according to claim 1, a fuel pellet hopper bin is positioned on
top with opening at bottom end to pass fuel to fuel feeder screw which conveys fuel pellets to
refractory dome.
4. The pellet burner apparatus according to claim 1 where in primary air is supplied to
bottom of grate which provides uniform air supply to enhance combustion of fuel and
secondary air supply through holes and slots to provide sufficient cooling at outer area of
combustion chamber and enhances complete combustion of fuel pellets.
5. The pellet burner apparatus according to claim 1 where in combustion air is supplied
through high speed air blower and directed through air box and blower duct for primary and

secondary air supply and controlled through blower speed.
6. The pellet burner apparatus according to claim 1, where in setup and design is constructed
for combustion of all types of fuel pellet as fuel source where in said pellets having an ash
content up to 10 % wt with length up to 30 mm and diameter up to 8 mm.
7. The pellet burner apparatus according to claim 1, wherein heater positioned inside refractory dome towards inlet of fuel pellets coming from fuel feeder screw and linked with PLC based controlled to auto-ignition of fuel pellets.
8. The pellet burner apparatus according to claim 1, wherein a grate system of burner oriented with electric cylinder 60 mm stroke with three grate, top and bottom are moving grate and middle fixed grate to remove the ash/clinker intermittently.
9. The pellets as claimed in claim 6, are made from wood, wood residue, forest left over, grasses, saw dust, agricultural residue, agro processing waste, biomass processing waste and with 6-8 mm dia, 20-30 mm length with ash percentage up to 10 wt %.
10. A self ignited solid biofuel pellet fired burner apparatus as herein described with
reference to foregoing drawings.