BG110642A - A biomass centre air jet burner - Google Patents

Abstract

Combustion equipment, allowing burning of biomass fuel, which includes a burner unit with biomass nozzle, concentrically surrounded by the active air zone, and spreading axially along the length of the active air zone, where the burner unit is situated in a vortex chamber, and the vortex chamber has the possibility to be connected with a boiler furnace. The burner unit has the possibility to be connected with the furnace through a burner mouth, through which is supplied air and fuel for the burner unit, and the same enter the furnace.

Description

FIELD OF THE INVENTION The present invention relates mainly to the field of industrial burner apparatus for performing fuel functions in energy production.

The term biomass as used herein describes a wide range of organic matter,

derived from different life or recently living organisms such as grasses and wood products. Sources of biomass include trees, mounds, shrubs, residual vegetation from harvest, grain and vegetables. Biomass is often a plant mass harvested to generate electricity or produce heat. Biomass can also include biodegradable organic waste that can be burned as fuel.

Biomass differs from fossil fuels, which are hydrocarbons found in the upper crust. Typical examples of fossil fuels include coal and oil. Unlike fossil fuels, biomass fuels are generally considered to be CO2 neutral and renewable sources, since the CO2 generated by burning biomass can be removed from the atmosphere by plants that provide biomass.

Because the physical properties and chemical composition of biomass differ significantly from that of coal, biomass fuels for energy production have in the past been used as primary or auxiliary fuels in flow boilers. These boilers do not rely on burners, which allows significantly more burning time in the furnace and therefore have low fuel preparation requirements. Global warming related to greenhouse gas emissions increases the interest in developing new technologies to allow for the extensive use of renewable energy sources. One area of such interest is the use of biomass fuels in fuel slurry, where fine grinding is required in the furnace for efficient combustion.

Crushed coal for heating is the main means of heating slurry in the production of electricity. In the first step, the coal is mechanically crushed into fine particulate matter. The particles are then fed through a suspension into the main air stream to the burner, where the burner pushes the air / fuel mixture into the combustion furnace. The residence time is provided from 1 to seconds, which is usually sufficient to completely pulverize the combustion coal with proper particle sizing.

[0007] Biomass heating in boilers using pulverized coal for heating is

becoming more and more common as part of the greenhouse gas reduction strategy. To implement this strategy, it is necessary to develop a burner capable of efficiently using biomass fuels in a fuel slurry.

Biomass heating fuels face many technical challenges. Compared to bituminous coal, biomass fuels have significantly lower heating values and higher volatile matter concentrations. The heating value is inversely proportional to the moisture content, so that it is equal to 25% to 75% of that of typical bituminous coal. Biomass moisture will often be reduced before ignition to effect material treatment and improve process efficiency. Nevertheless, burning biomass instead of coal requires significantly more fuel mass to achieve relatively good heat. In addition, while highly volatile biomass can easily ignite the fuel, the high moisture content can slow the ignition. Ignition delay is particularly undesirable in combustion slurry.

Another concern with biomass fuels is that this biomass is not treated to the same size as powdered coal. Experience has shown that successful suspension of fuel can be achieved with wood particles of 0.0625 inches, resembling the above size for 0.012 inch coal. The volume of the particle varies with the diameter of the cubes, thus making the wood particles about 150 times smaller than the volume of the larger coal particles used to suspend the fuel. The larger volume of biomass thus requires rapid combustion and rapid combustion, facilitating the use of biomass in furnaces designed for coal dust.

A known technique for the use of biomass in fuel suspensions is combined combustion of biomass. In this technique, the biomass particle is combined with powdered coal and primary air in a single stream. The total flow is then introduced into the furnace. However, this technique is of limited practicality due to the fact that the resulting burner nozzle velocity is required to maintain two types of particles in suspension. Excessive velocity of the burner nozzle results in unstable flames, slow ignition, and poor fuel characteristics.

So there remains a need to develop means for an efficient and effective alternative to burning coal for energy production and means that allow the widespread burning of carbon-neutral fuel for applications in energy production.

SUMMARY OF THE INVENTION Embodiments of the present invention provide a new combustion apparatus. Specifically, embodiments of the present invention provide a combustion apparatus capable of burning biomass fuel and alternating between biomass and combustion coal, if necessary, and / or combining a combination of coal and biomass fuel simultaneously.

Embodiments of the present invention capture the potential capabilities of prior art burners. US Patent 7,430,970 e

incorporated herein by reference.

The present invention is an improvement of the prior art burners by providing a new combustion apparatus for combustible fuels, but not limited to biomass.

Embodiments of the present invention provide a better method and apparatus for combined combustion of biomass together with powdered coal.

Combustion apparatus capable of burning biomass fuel comprising a burner assembly comprising a biomass nozzle concentrically surrounded by an active air zone and extending axially along the active air zone, the burner assembly being placed in a vortex chamber, and the vortex chamber is connected to the furnace of a boiler, and the burner unit is capable of being connected to the furnace by a throat through which the air and fuel supplied to the burner assembly are connected to the furnace. In embodiments of the present invention, the apparatus includes a cooling fan providing a first airflow to the vortex chamber, an active air duct enclosing the active air zone to receive a substantive portion of the first air intake, with the active air duct active a regulator for regulating the inlet active portion in the active air duct, an active nozzle for supplying said active portion to said burner neck, a burner elbow for producing coal dust and a second inflow of air passing through the coil nozzle into the narrow annular space formed between the active nozzle and the coal nozzle, the active portion serving to accelerate the ignition of powdered coal by connecting to an internal cylinder of coal jet leaving the nozzle for the coal nozzle. serves to accelerate combustion.

The various novel features that characterize the invention are set forth in detail in the appended claims for formulating this disclosure. For a better understanding of the invention, its advantages and specific objects are achieved through its applications, referring to the accompanying drawings and description, where a preferred embodiment of the invention is shown.

Brief Description of the Drawings [0019] The Drawings:

Figure 1 is a schematic sectional view of an embodiment of the present invention; Figure 2 is a schematic sectional view of a variant embodiment of the present invention;

Figure 3 is a schematic sectional view of a variant embodiment of the present invention;

Figure 4 is a schematic cross-sectional view of an embodiment of the present invention that identifies concentric zones of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, in which the same designations define the same or functionally similar elements of several drawings, such as FIG. 1 shows a burner assembly 1 housed in a vortex chamber 2 that is connected to a boiler furnace 3 (not shown). Secondary air 22 is supplied to the vortex chamber 2 by a cooling fan (not shown) and heated by an air heater (not shown). The burner assembly 1 is connected to the furnace 3 via a burner neck 4 through which air and fuel are supplied to the burner assembly 1 discharged into the furnace 3. Part of the secondary air 22 represents active air 5. The active air 5 enters an active air pipe 6 and is regulated by an active air regulator 7. The active air 5 continues through the burner assembly 1, through the active nozzle 8 and exits through the burner neck 4.

Secondary air 22 is also provided to the burner assembly (designated as secondary air to the burner assembly 9). The secondary air 22 enters the burner assembly 1 and passes to the parallel flow portions of the inner air zone 10 and the outer air zone 11. The swirling wings in these zones serve to rotate the secondary air 22 to assist the ignition and combustion of the secondary air 22, which is in contact with the shattered coal stream. The air separation wing 12 at the outlet of the outer zone 11 helps to increase the size of the internal recirculation zone (ARI) formed by aerodynamics. Spent coal and basic air 13 enter the knee of the burner 14 and continue through the coal nozzle 15 into a narrow annular space formed between the active nozzle 8 and the nozzle 15. The active air 5 serves to accelerate the ignition of powdered coal by connecting the inner cylinder for the coal stream (not shown) leaving the coal nozzle 15; and serves to accelerate the combustion by blowing the air into the center of the flame. US 7 430 970 provides a detailed explanation of the accelerated ignition applied to the active air.

The burner assembly 1 according to embodiments of the present invention can be used in combination with an air supply system above the combustion zone (not shown). Part of the secondary air 22 supplied to the combustion furnace is provided to the air supply system above the combustion zone so that the total amount of air supplied to the burner assembly 1 is less than the required air theoretically. This results in the dilution of the furnace medium before the air supply system above the combustion zone is energized. Accelerated combustion, high flame temperature, and higher IRZs all serve to reduce NOx more effectively.

In embodiments of the present invention, biomass can be prepared for slurry used in crushers, mills, and the like (not shown), collected and controlled by percent feed through a screw feeder or equivalent device (not shown) and pneumatically conveyed to the burner unit 1 through a suitable pipeline The pipeline supplies biomass and transports air 16 through the knee 14, the outlet of which is located in the axis of the burner assembly 1.

In some embodiments, a reduction valve 17 may be used to reduce the cross-sectional area of the biomass nozzle 18, the nozzle being transverse to the burner knee 14 and extending through the active air duct 16. The reducing valve 17 serves to reduce congestion. as the biomass nozzle 18 extends over the length of the burner assembly 1. Near the furnace, the burner assembly 1 ends, and the diameter of the tip of the biomass nozzle 19 can be expanded as shown (Figure 1) to reduce the biomass output velocity n and the optimum value for combustion. In some embodiments, this output velocity is between about 2500 ft / min and about 5000 ft / min, and preferably between about 3000 ft / min and 4000 ft / min.

In a further embodiment, active air 5 surrounds the tip of the biomass nozzle 19 and serves to accelerate the ignition of the biomass as it enters the burner neck 4 and supplies air to feed the combustion as the biomass continues into the furnace. The hot secondary indoor air that surrounds the biomass nozzle provides heat to allow additional moisture to be removed from the biomass

fuel, while supplying fuel with oxidant to facilitate ignition and combustion. This solves the problem of the delayed ignition and combustion characteristic of the biomass burning in the prior art burners. Active air regulator 7 is configured to supply active air 5 in such an amount that the NOx emissions of the biomass in combination with powdered coal are minimized. In cases where the biomass is incapable of burning, the biomass supply system (not shown) serving the burner unit 1 is closed by closing the valve 23. The valve 21 is then opened and adjusted in combination with the active biomass. regulator 7 to supply the optimum amount of active air 5 required to reduce NOx when coal is burned. When the biomass is to be ignited, valve 21 is closed and valve 23 is opened for biomass leakage and air transfer 16.

Referring to FIG. 4, which shows a cross section of burner assembly 1 of the present invention, shows five distinct zones of burner assembly 1. The biomass zone 32 defined by the biomass nozzle 18 is concentrically surrounded by an active air zone 44 forming the space between the biomass nozzle. and the active nozzle 8. The coal nozzle 15 concentrically encircles the active nozzle 8 defining a first annular zone 47, where coal and primary air pass 13. The cylinder 42 concentrically encircles the nozzle 15 and

determines the inner air zone 10 which is internal to the cylinder 42 and the outer air zone 11 which is external to the cylinder 42.

Although a preferred embodiment is shown, alternative embodiments are also feasible without departing from the scope of the present invention.

An alternative embodiment includes a straight pipe without a reducing valve 17 (Fig. 2), and / or without expansion to the furnace at the end of the biomass nozzle 18. In this embodiment, it is also shown as an alternative to a shorter or discontinuous biomass nozzle 18, with the tip of the biomass nozzle 19 ending in the active nozzle 8 adjacent to the active air duct 6. This embodiment provides the additional advantage of preheating and pre-mixing the biomass with the active air, thus adding additional moisture extracted from the biomass fuel.

A reduced conical portion may be used at the outlet of the biomass nozzle 18 (Figure 3) to accelerate the biomass fuel, entering the furnace 3 to prevent return to the biomass nozzle 18. Although the biomass nozzle 18 is illustrated in the figures as open end nozzle, it can easily be equipped with deflectors or vortices located near the outlet to increase the degree of mixing of biomass with the active air.

In other embodiments, adjusting means may be included to assist the minor front / rear adjustment in the end position of the biomass nozzle 18 relative to the active tube to further optimize combustion. Although the biomass nozzle 18 is shown parallel to the end of the active tube in Figure 1, it can be positioned slightly forward or forward. In some embodiments, a valve 21 may be used to pass a small amount of air or hot secondary air or unheated air to add air inside the flame while burning biomass. The purpose of this is to increase the stoichiometric center to the lowest NOx (as an alternative to increasing the amount of air transported).

Embodiments of the present invention offer a number of advantages. The biomass co-firing jet burner according to embodiments of the present invention provides a new, better structure and enables a better method of burning biomass fuels.

The large core receiving the biomass nozzle, without changing the burner size, saves engineering and manufacturing costs, which are usually associated with the construction of burners of various sizes for adaptation to biomass combustion.

The large biomass nozzle allows the burning of more biomass in selected burners such that fewer burners are needed to feed the biomass. Biomass combustion is up to 40% of burner capacity, allowing biomass combustion of up to 20% when only half of the burners are used.

Supplies of biomass fuel often vary depending on the season, so biomass burning cannot be done continuously. Alternatively, the biomass nozzle may be supplied with secondary air when the biomass is not burning so that both the biomass nozzle 18 and the active nozzle 8 provide a combined active air stream for burning coal dust.

Also, biomass air transfer contributes to the preferred stoichiometric center of the burner when burning biomass in combination with coal. In this case, the coal flow is reduced so that a higher RA / PC ratio is applied to the burner. It is increased by the transfer of biomass air to supply a very low NOx emission stoichiometric center.

In addition, the location of a biomass nozzle in the core provides

a source of hot secondary air to ignite and feed the combustion of biomass fuel, and prevents the delayed ignition of the prior art, as well as feeds the combustion of co-ignited biomass fuel.

Although a specific embodiment of the present invention is shown and described in detail to illustrate the application of the principles of the invention, it should be understood that the invention may have another embodiment without violating those principles.

Claims (20)

Patent Claims 1. Combustion apparatus capable of burning biomass fuel containing: a burner assembly consisting of a biomass nozzle concentrically surrounded by an active air zone and extending along said active air zone, said burner assembly being disposed in a vortex chamber and said vortex chamber being connected to the furnace of the boiler in which said boiler furnace a burner unit capable of being connected to said furnace by a burner throat through which air and fuel are supplied to the burner unit introduced into the furnace; a power fan providing the first supply of air to said vortex chamber; an active air duct comprising said active air zone for receiving a substantive portion of said first air delivery, the active air duct having an active regulator for regulating said active portion entering the active air duct; an active nozzle for receiving said active portion of said active air duct, said active nozzle delivering said active portion to the burner neck; elbow for accepting coal dust and second delivery of air; said powdered coal and said second air delivery continuing through a coal nozzle, in a narrow annular space formed between said active nozzle and said coal nozzle, said active portion serving to accelerate the ignition of the powdered coal by connecting with internal combustion for coal leaving said coal nozzle; said active part also serving to accelerate combustion. Combustion apparatus according to claim 1, characterized in that said burner assembly operates in combination with an air supply system above the combustion zone. Combustion apparatus according to claim 1, further comprising a regulator for reducing the cross section of said biomass nozzle. The combustion apparatus of claim 1, further comprising a tapered cone portion mounted at the outlet of the biomass nozzle to accelerate the biomass fuel, said biomass fuel entering the furnace and preventing it from returning to said biomass nozzle. 5. The combustion apparatus of claim 1, further comprising at least one reflector located near the outlet of the biomass nozzle to increase the degree of mixing of said biomass fuel with the active portion. Combustion apparatus according to claim 1, further comprising at least one vortex, which is located near the outlet of the biomass nozzle to increase the degree of mixing of said biomass fuel with the active part. 7. The combustion apparatus of claim 1, wherein the first supply of air is heated by an air heater. The method of using a combustion apparatus according to claim 1, comprising providing a first valve and a second valve, wherein when the biomass is not delivered said first valve is closed and said second valve is open and regulates with said active regulator the supply of the required amount of said active portion, and when the biomass is supplied, said second valve is closed and said first valve is open for biomass leakage and air transfer. 9. An air jet burner having a biomass center comprising a biomass tube defining a biomass zone where an axial tube concentrically surrounds the biomass tube and there is a defined axial zone between them and a annular tube concentrically surrounds the axial tube and there is defined a first annular zone between them. , in which the cylinder concentrically surrounds the annular tube and there is defined a second annular zone between them, and a burner wall concentrically surrounds the cylinder and there is defined a third annular zone between therewith, the active air duct being radially inserted between the axial tube and the annular tube, wherein the active air duct provides fluid communication between the axial zone and the vortex chamber, and means for improving the sputtering of coal falling around a portion of the supply duct placed in the first annular zone. 10. Burner according to claim 9, characterized in that the biomass tube has a nozzle with a pointed end which terminates in the axial tube and before the active air channel. A burner according to claim 9, characterized in that the biomass tube has a nozzle with a pointed end which terminates inside the burner and down the active air duct. A burner according to claim 11, characterized in that the tapered end of the biomass nozzle extends radially inside the burner. 13. Burner according to claim 11, characterized in that the tapered end of the biomass nozzle narrows radially inside the burner. 14. Burner according to claim 11, characterized in that the biomass tube further comprises an inflow valve. 15. Burner according to claim 14, characterized in that the biomass nozzle is longitudinally adjustable along the burner. 16. Burner according to claim 15, characterized in that the first annular zone comprises a flow enhancing device. A burner according to claim 16, characterized in that the biomass pipe further comprises a reducing valve downstream of the inflow valve. 18. Burner according to claim 11, further comprising means for supplying the first annular powder coals zone and separating means for supplying the biomass pipe with biomass fuel. 19. Burner according to claim 17, further comprising means for supplying the first annular powder coals zone and separating means for supplying the biomass pipe with biomass fuel. 20. A burner according to claim 11, further comprising a wing in the second annular zone, a wing in the third annular zone, wherein the second annular zone and the third annular zone are connected via fluid to the vortex chamber.