HORNET IULIEAN (RO)
HORNET IULIEAN (RO)
| CLAIMS 1. Gravity burner for burning wood pellet biomass, that consists of a combustion dozer provided with an L-shaped grating at the inferior side located on one of the side walls, toward the up side of the chamber, a microparticle coagulation area where the secondary air penetrates evenly and the gases burn completely, a system for admission and distribution of the preheated air through the absorption tubes covering the burnt gas exhaust tubes of the equipment that incorporates it and which, at the outside end, has mounted an exhauster, of an ash pan, of a metallic case with support elements, of a coupling system to the wood pellet hopper and of a slot for burnt gas transfer at the temperature set in the equipment that incorporates it. 2. Gravity burner, according to the claim 1 , characterized by that the vertical wall 28 lowers under the grating 24 of the microparticle coagulation and full burning area 23, in such way that with the secondary air admission direction becomes an ash deflector. 3. Gravity burner, according to the claim 2, characterized by that the wall 46 of the ash pan 40 is sized in such way that it retains the ash and creates the slot 60. 4. Gravity burner, according to the claim 3, characterized by that the opening 52 provided in the air distribution chamber 30 ensures the absorption of the preheated air. 5. Gravity burner, according to the claim 4, characterized by that it can also work with air taken from the area where the equipment incorporating it was mounted in, through the openings provided in the access door 61 and in the wall 52. 6. Gravity burner, according to the claim 5, which consists also of an even dosing system 46 of the wood pellet biomass, located outside the radiation area of the combustion chamber at an angle > 45°, controlled by a motor which is controlled, at its turn, by a sensor 38 with the help of a level indicator 29. 7. Gravity burner, according to the claim 6, which is characterized by the geometry of the air distribution system that consists of some line pipes 54 located inside the combustion chamber in an air distribution chamber 30, confined at one side by the profile 50 and by the wall 51 , that, considering the location manner against the deflector 34, creates two air absorption slots, in both the combustion chamber 20 and in the microparticle coagulation and full burning chamber 23, confined at one side by the wall 52 and at the other sides by the side walls of the burner. 8. The wood pellet biomass burning process is characterized by that the firing is achieved simultaneously on the entire length of the combustion chamber 20, at the base of the grating 21 where the firing device is located 22, grating that has an active length similar to the one of the combustion chamber 20 and from where the initial combustion area A extends up to not less the level of the line pipes 54, on the width of the combustion chamber 20, as well as on its height, forming in short time two incandescent pellet layers at temperatures higher than 1000° C, one at the base of the grating 21 and another one on the grating 24, forming the microparticle coagulation and full burning area 23, through the air distribution manner where, after reaching the set temperature, the combustion air is closed and the secondary air is reduced. |
PELLET BIOMASS BURNING PROCESS
This invention refers to a gravity burner and to a burning process of the pellet biomass, with the purpose to produce thermal and electrical energy through integration with a proper equipment, starting from a power equal to 2 to 3 kw and reaching up to a power sufficiently high, by using modular burners.
There are various types of burners and pellet biomass burning processes. The burners could be grouped based on many criteria, out of which the following stand out: the supply type and the burning process.
The gravity supply consists of the pellet falling in the combustion chamber through a line pipe, and then the pellet is taken by a dozer inside the hopper. The supply is achieved by pushing with screws the pellet from down to up in a combustion chamber, sized according to the power required from the burner (US 4.989.521 - US 6.397.833 - US 5.001.993 US 5297493).
The burning processes commonly used are the fixed-bed combustion and the fluid-bed combustion, where the pellet biomass is combined with grain coal.
The major inconveniences of the equipment using gravity burners are the following:
- continuous smoke emissions in the combustion gases;
- soot and creosote deposits in the heat exchangers, with substantial reduction of the performance of this equipment;
The main inconvenient of the equipment provided with burners with down- to-top supply consists of the obstruction of the opening that allows for the entry of the combustion air, due in particular to the powder (sand) contained by the pellet biomass, although their level in the combustion chamber is optimum. Supercharging means pellet overfall in the ash-pan, burning with a lot of smoke, soot and creosote deposits, performance reduction and the need for action to clear the opening and to provide optimum operation of the equipment, which, in many cases, only lasts for just few hours. The diminution of the frequency of the actions needed to clear the openings was achieved by producing wood pellets of less powder, but much more expensive and having a negative influence upon the NOx and microparticle emissions in the atmosphere (Henrik Wiinikka - doctoral dissertation: High Temperature Aerosol Formation and Emission Minimisation during combustion of Wood Pellets )
Due to the shown drawbacks of the existing burners, the wood pellet biomass couldn't be used in the radiant tube heaters for industrial, social and agricultural spaces and their use was limited to the co-production equipment with turbines or Stirling motors.
The technical issue that the invention solves is full reduction of smoke emissions and creosote deposits, constant maintenance of the efficiency of the equipment provided with gravity burners, which give the opportunity to achieve the pellet biomass burning process according to the invention and the extension of the wood pellet biomass utilization to radiant tube burning equipment and co- generation equipment. At the same time, through the combustion process stated by the invention and based on the opportunity to use the wood pellet biomass in the gravity burner without being affected by the powder (sand) quantity contained by the biomass, the NOx and the microparticle quantities released in the atmosphere are reduced.
According to the invention, the gravity burner solves the technical issue for it consists of a dozer, of a combustion chamber with grating on the inferior side, an L-shaped grating located on one of the side walls to the up side of the chamber, a microparticle coagulation area where the secondary air penetrates evenly and the gases are fully burnt, of a distribution system for the preheated air coming from the absorption tubes that cover the gas discharge tubes of the equipment that incorporates it and at the end of which an exhauster is mounted, of an ash-pan, of a metallic case with support elements, of a coupling system to the wood pellet hopper and of a slot for the transfer of the burnt gases at a certain temperature. According to the invention, the wood pellet biomass burning process solves the technical issue for the combustion takes place simultaneously over the entire length of the combustion chamber at the base of the grating where the firing device is located and from where the combustion area extends fast to both the width of the combustion chamber and to its height forming two incandescent layers of pellets, at temperatures higher than 1000 0 C, one at the base of the combustion chamber's grating and another one on the grating of microparticle coagulation and full gas burning area through the access of the secondary air and based on the air distribution manner when reaching the temperature set in the equipment that incorporates the gravity burner.
The benefits of the invention are as it follows:
- environment protection through full reduction of smoke and through reduction of NOx and microparticle emissions in the atmosphere;
- constant maintenance of the performance of the equipment that incorporates the gravity burner due to the removal of soot and creosote deposits;
- extension of wood pellet biomass utilization by incorporating the gravity burner, according to the invention, in radiant tube heaters and in co-generation equipment provided with turbine or Stirling motors;
- to achieve high power equipment, it incorporates many gravity burners build according to the invention, for these have well fixed sizes leading to the wood pellet biomass burning process taking place as per the invention and, hence, to obtaining the above mentioned advantages.
An example of the invention achievement is showed further, related also to fig. 1 located under a hopper through the dosing chamber 45 which includes a dosing system 46 controlled by a sensor 28 through a level indicator 29. The combustion chamber 20 is confined at the inferior side by an L-shaped grating 21 to which it was welded a deflector 34 at 30°- 50°, guiding this way the secondary air to the microparticle coagulation and full burning area 23, located in the space between the grating 21 of the combustion chamber 20, the grating 24 and the side walls. At the same time, the grating 21 is welded to a profile 36 which is clamped by some joint pins 37 to the dosing chamber 45 providing the heat break through a ceramic wool seal 26 .
The wall 28 which is common to the combustion chamber 20 and to the microparticle coagulation and full burning area 23 lowers under the level of the grating 24 at a quota that also offers it the role of deflector of the ash driven by the secondary air. Under the grating 23 the ash pan 40 is located, that the wall 46 of which plays the role of ash deflector and, with the help of the walls 28 and 47, guides burnt gas absorption to the equipment incorporating the gravity burner, according to the invention.
On the deflector 34, in contact with the grating 21, the electrical resistance 22 is settled, having an active length equal to the length of the combustion chamber 20. The chamber 30, called the air distribution chamber, is confined by the profile 50, by the wall 51, which, due to its location against the deflector 34, creates the two air absorption slots, one in the combustion chamber 20 and another in the microparticle coagulation and full burning area 23, by the wall 53 and by the side walls. The air preheated in the already known tube-in-tube system from the burnt gas discharge line pipe of the equipment that incorporates the gravity burner, according to the invention, and that at the end outside the building has mounted an exhauster, is absorbed in the air distribution chamber 30 through the opening 52. The electromagnetic bolt 33 through the arrester 34 controlled by a temperature regulator, closes fully the combustion air admission and partially the secondary air, when exceeding the set temperature, and opens air admission when the temperature has dropped under the set value.
The equipment that incorporates the gravity burner, according to the invention, is also provided with a thermocouple or a thermal resistance applied on/inside the line pipe or on/inside the caldron where the heating agent circulates and sends signals to the temperature regulator.
The wood pellet biomass burning process, according to the invention and as shown in fig. 1, consists of even distribution of the combustion air on the entire width of the combustion chamber through some line pipes 54 provided with openings on the inferior side.
The location area of the electrical firing resistance 22 and its active length, that matches the length of the combustion chamber 20, allows for firing the wood pellet biomass, located in the area A, and, based on the guiding manner of both the combustion air and of the secondary air, ensures a smokeless full burning from the start.
The progressive extension of the burning area, according to the curves represented by discontinuous lines fig. 1 , up to the level of the line pipes 54, is rapidly achieved due to the distribution of the combustion air as well as for the wood pellet biomass has low humidity. From this moment, above the grating 21, on a height of 15 to 20 mm, for the entire burning period an incandescent pellet bed almost completely burnt will exist, which makes that a part of the combustion air that passes through it plays the role of secondary air, changes this way the ratio between the combustion air and the secondary air and has a positive influence upon the formation of microparticles. The burnt pellet reduces in diameter and falls on the grating 24 in the microparticle coagulation area and in the admission of secondary air area, where it forms another incandescent bed that filters the microparticles driven by the air in the combustion chamber and the microparticles driven by the secondary air from the surface of the incandescent bed. Through continuous wood pellet transfer from one incandescent bed to another and then to the ash pan an optimum combustion regime and the coagulation of massive quantities of microparticles are achieved.
The geometry of the air distribution chamber allows for a continuous change of the ratio combustion air - secondary air. According to the invention, the admission in the gravity burner of only the secondary air when this reaches the set temperature, for a period of time, determines the microparticle coagulation and, implicitly, significant reduction of the quantity released in the atmosphere.
According to the invention, the utilization of the gravity burner and of the wood pellet grain biomass burning process, in a modular system incorporated in a high power equipment, gives the opportunity to stop one or more burners, based on the power needed in various periods, and allowing the others to work at a optimum regime.
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