LANCE FOR BURNERS”

TECHNICAL FIELD

The present invention pertains to the technical field of fuelburning lances for burners, referring more specifically to booms for burning tar and liquefied petroleum gas (LPG).

DESCRIPTION OF THE PRIOR ART

Fossil fuels still play a very important role in maintaining our current way of life, meeting a very high percentage of the world's energy demands. Fossil fuels played a key role in the industrial revolution, when the heat generated by burning coal was used to produce steam, which in turn made it possible to move machinery. In more recent decades, oil has gained more prominence among the different fossil fuel options used in industry, giving rise to several types of derivatives, such as diesel oil, kerosene, LPG, petrol, and natural gas. Fossil fuels are organic compounds that release carbon dioxide when burned, and therefore make an increasing contribution to the greenhouse effect. Furthermore, the carbon monoxide released as a result of incomplete combustion of the fuel also pollutes the atmosphere.

The industry's high dependence on fossil fuels to generate heat energy is becoming a problem as environmental concerns and sustainability become key issues in the modern world.

An alternative to fossil fuels with great potential for use in industry is wood tar, a black viscous residue with high added value. Wood tar is obtained as a by-product in the charcoal production process, coming from continuously cultivated, renewable forests. It is a solution with a lower environmental impact that remains relatively unexplored in the industry.

In this regard, document CN103528074 B describes a substantially tubular spray lance capable of incinerating residual tar. This lance has a tar inlet, a premix section, a primary acceleration section, a spray mixing section, a secondary acceleration section, a secondary atomization steam nozzle, and a steam injection nozzle.

Document CN209524509 II discloses a spray granulation device that uses tar as fuel and is intended for the ceramics industry. The device is tubular and comprises an inner pipe for air and an outer pipe for oil. The device has a spray blade at one end, which contains three holes for outputting the oil-gas mix.

It should be noted that a number of disadvantages and technical limitations have been found in the technologies in the prior art. Some lances have simplified structures, but are not suitable for burning wood tar. There are also lances with very complex structures, which generate higher costs and manufacturing difficulties. Other problems include losses generated in the combustion process, which reduces the efficiency of the burners. There are also problems caused by clogging of equipment parts, which inevitably lead to higher losses.

OBJECTIVES OF THE INVENTION

One of the objectives of the present invention is to provide a fuel-burning lance that is suitable for use in combustion applications, such as for thermal power generation. In orderto meet increasingly stringent environmental requirements, the lance according to the invention is specially adapted to use wood tar as fuel, and is also naturally adapted for use with traditional fossil fuels, such as diesel.

Another objective of the present invention is to provide a burning lance that is ease, simple and cheap to build, using simple and widely accessible materials.

Another important objective is to provide a burning lance that ensures optimal, efficient and complete combustion, while minimizing energy losses. Furthermore, the risk of clogging of the lance is minimized, which reduces maintenance and cleaning costs, among others. SHORT DESCRIPTION OF THE INVENTION

The lance comprises a main tubular assembly, a pilot ignition assembly, and a tubular housing assembly.

The main tubular assembly comprises: a compressed air pipe, a first fuel pipe, which is arranged coaxially with and outside the compressed air pipe, forming a first flow space for a first fuel, preferably a liquid fuel, and a second fuel pipe, which is arranged coaxially with and outside the first fuel pipe, forming a second flow space for a second fuel, preferably a gas fuel. The pilot ignition assembly is a substantially tubular lance for conveying fuel ignition means. In a preferred embodiment of the present invention, the ignition means is an LPG pilot flame. The tubular housing assembly houses the main tubular assembly and the pilot ignition assembly.

In a preferred embodiment of the present invention, the compressed air pipe has two ends. The first end has a compressed air inlet and the second end has a compressed air nozzle. The compressed air nozzle has a substantially frustoconical shape with a cylindrical end, and has a first set of through-holes through which compressed air is discharged under pressure. The first set of through-holes comprises eight holes arranged circumferentially, preferably offset at 45° from each other.

Advantageously, the first fuel pipe has two ends, in which there is a first-fuel inlet, preferably for a liquid fuel, close to the first end and the second end has a fuel nozzle that fits together externally with the compressed air nozzle of the compressed air pipe. The fuel nozzle has a second set of through-holes through which the first fuel is discharged under pressure. Preferably, the second set of through-holes in the fuel nozzle is similar to the first set of through-holes in the compressed air nozzle, and the first and second sets of through-holes are aligned with each other. In an advantageous embodiment, the second fuel pipe has two ends, with the first end having a second-fuel inlet (preferably for LPG) and the second end having a third set of through-holes through which the second fuel is discharged under pressure. The second fuel pipe has a set of vanes arranged on the outer surface thereof near to the third set of through-holes, which are designed to generate an external air flow for burning the first and/or second fuels.

Advantageously, the tubular housing assembly has two ends and an external combustion air inlet, with a flange at a first end. The flange positions and fastens the main tubular assembly and the pilot ignition assembly inside the tubular housing assembly. In another advantageous embodiment, the compressed air nozzle, the fuel nozzle, and the third set of through-holes of the second fuel pipe project beyond the second end of the tubular housing assembly, so that the first, second, and third sets of through-holes are exposed to the environment inside the combustion chamber.

In a preferred embodiment of the invention, the first fuel is tar or diesel, and the second fuel is LPG.

SHORT DESCRIPTION OF THE FIGURES

The present invention is described below with reference to a preferred embodiment shown in the drawing.

Figure 1 is a schematic side view of the main components of the lance according to the present invention,

Figure 2 shows the main components of the main tubular assembly,

Figure 3 shows the compressed air pipe of the main tubular assembly,

Figure 4 shows the first fuel pipe of the main tubular assembly,

Figure 5 shows the compressed air pipe assembled with the first fuel pipe,

Figure 6a is a detailed cutaway view of the compressed air nozzle and the fuel nozzle,

Figure 6b is a front view of the compressed air nozzle and the fuel nozzle,

Figure 7 shows the second fuel pipe of the main tubular assembly,

Figure 8 shows the main components of the tubular housing assembly,

Figure 9 shows the arrangement of the main tubular assembly and the pilot ignition assembly in relation to the tubular housing assembly using the flange, and

Figure 10 shows the lance according to the present invention installed in a combustion chamber.

DETAILED DESCRIPTION OF THE DRAWINGS

As shown in Figure 1 , the lance 1 according to the present invention has a simple structure and is made of cheap, widely accessible materials, such as pipes and flanges, preferably made of steel, in particular stainless steel. In order to facilitate understanding of the main components of the lance 1 and how said components are arranged and installed together, as well as the specific functions of the lance 1 when in use, the lance 1 can be split into a main tubular assembly 2, a pilot ignition assembly 3, and a tubular housing assembly 4.

Figure 2 shows the three main components of the main tubular assembly 2, specifically the compressed air pipe 5, the first fuel pipe 6 (preferably for liquid fuel, such as wood tar or diesel) and the second fuel pipe 7 (preferably for gas fuel such as LPG). The main tubular assembly 2 plays a central role in the operation of the lance 1 according to the present invention, since said assembly receives the compressed air and fuel(s) and discharges said the compressed air and fuel(s) under pressure into the combustion chamber of a burner, forming a fuel mist. Another function of the main tubular assembly 2 is to provide enough outside air to enable combustion with the fuel mist inside the burner. In the preferred embodiment shown in this figure, the compressed air pipe 5, the first fuel pipe 6, and the second fuel pipe 7 are fastened together by screwing using metal plates arranged at the ends thereof. This solution makes the lance 1 according to the present invention more versatile, enabling quick and easy assembly and disassembly of the entire assembly using screws. Other means for fastening the different components of the main tubular assembly 2 together are available to the person skilled in the art, such as threading between the pipes or welding the pipe ends.

Figure 3 shows the compressed air pipe 5 of the main tubular assembly 2, which has two ends. A compressed air inlet 8 designed to receive compressed air from an external source is fastened to a first end of the compressed air pipe 5, preferably by threading or welding. A compressed air nozzle 9 is fastened to the second end of the compressed air pipe 6, preferably by threading or welding.

In the preferred embodiment of the present invention, the compressed air nozzle 9 has a cylindrical section of greater diameter, an intermediate conical section, and a cylindrical section of lesser diameter, in which the diameter of the cylindrical section of greater diameter is preferably equal to the diameter of the compressed air pipe 5. The compressed air nozzle 9, and more specifically the conical section thereof, has a first set of through-holes 12, preferably formed by eight holes of equal diameter, this number of holes being variable depending on the design specifications. During operation of the lance 1 , compressed air is fed through the compressed air inlet 8 and travels the length of the compressed air pipe 5 before being discharged under pressure through the holes of the first set of through-holes 12 in the compressed air nozzle 8. In a preferred embodiment of the present invention, the compressed air inlet 8 is a 1/2" stainless steel half-coupling, the compressed air pipe 5 is a 3/4" stainless steel pipe, in particular 630 mm long, and the compressed air nozzle 9 is manufactured by turning a stainless steel billet.

Figure 4 shows the first fuel pipe 6 of the main tubular assembly 2, which has two ends. A first-fuel inlet 10 designed to receive a first fuel from an external source is fastened close to a first end of the first fuel pipe 6, preferably by threading or welding, and transversely in relation to the fuel pipe 6. In the preferred operating mode of the present invention, the first fuel fed through the first-fuel inlet 10 is preferably liquid fuel, in particular wood tar or diesel.

A fuel nozzle 11 is fastened to the second end of the first compressed air pipe 6. The fuel nozzle 11 is preferably fastened to the first compressed air pipe 6 by threading, which enables easy assembly and disassembly of these two components. However, these components can also be fastened by other means, such as welding. In the preferred embodiment of the present invention, the fuel nozzle 1 1 has a cylindrical section and a conical section, in which the diameter of the cylindrical section is preferably equal to the diameter of the first fuel pipe 6, and has a centre hole. The conical section of the fuel nozzle 1 1 has a second set of through-holes 13, in particular comprising eight holes of equal diameter. Indeed, the second set of through-holes 13 is preferably similar to the first set of through-holes 12 of the compressed air nozzle 9 of the compressed air pipe 5, i.e. the holes have the same diameters and are spaced apart by the same distance, so that when the lance is assembled (as described in greater detail below), the holes of the set of through- holes 12 of the compressed air nozzle 5 are aligned with the holes of the set of through-holes 13 of the fuel nozzle 11. During operation of the lance 1 , the first fuel, preferably a liquid fuel, in particular wood tar or diesel, is fed through the first-fuel inlet 10 and travels the length of the fuel pipe 6 before being discharged under pressure through the holes of the second set of through-holes 13 of the fuel nozzle 1 1 .

In a preferred embodiment of the present invention, the first- fuel inlet 10 is a 1/2" stainless steel half-coupling, the first fuel pipe 6 is a 1.1/4" stainless steel pipe (of greater diameter than the first compressed air pipe 5), in particular 600 mm long, and the fuel nozzle 11 is manufactured by turning a stainless steel billet.

When manufacturing and assembling the lance 1 according to the present invention, the compressed air pipe 5 is inserted into the first fuel pipe 6, as shown in Figure 5. To fasten these components, a metal plate with screw holes is preferably placed at one end of the first fuel pipe 6, which enables the two pipes to be fastened together precisely. Another possible solution is to weld the two pipes together, although this does not enable later disassembly. Additionally, the cylindrical section of lesser diameter of the compressed air nozzle 9 passes through the centre hole of the fuel nozzle 11. As a result, the first fuel pipe 6 is arranged coaxially with and outside the compressed air pipe 5, enclosing said pipe. Since the compressed air pipe 5 is longer than the first fuel pipe 6, part of the length thereof is exposed when the two pipes are assembled, including the compressed air inlet 8 (left end in Figure 5).

Figure 6a is a detailed view of the relative arrangement of the compressed air pipe 5 and the first fuel pipe 6 when assembled. As shown, the cylindrical section of lesser diameter of the compressed air nozzle 9 passes through the centre hole of the fuel nozzle 11 . As shown, a first space, preferably of annular cross section, is formed between the internal diameter of the first fuel pipe 6 and the external diameter of the compressed air pipe 5. When the first fuel is fed into the first-fuel inlet 10, the fuel flows along the length of the first fuel pipe 6 through the first space.

Furthermore and as shown, the first set of through-holes 12 of the compressed air nozzle 9 is aligned with the second set of through- holes 13 of the fuel nozzle 11. The holes are preferably inclined at 30° to the longitudinal axis of the pipes. As a result, when compressed air is discharged under pressure from inside the compressed air pipe 5 through the first set of through-holes 12 of the compressed air nozzle 9, said compressed air comes into contact with the first fuel in the first space. This helps to discharge the first fuel through the second set of through-holes 13 of the fuel nozzle 10, thereby forming a fuel mist.

Figure 6b is a front view of the previous figure, showing the conical section of the fuel nozzle 10 and, at the centre thereof, the front face of the cylindrical section of lesser diameter of the compressed air nozzle 9. This front view shows the preferred arrangement of the holes in the second set of through-holes 13, in which there are eight through- holes arranged circumferentially and spaced apart equidistantly, offset by 45° from each other, and the diameter of the holes is preferably 4 mm. Testing has revealed that this particular hole configuration provides optimal fuel mist formation and subsequently more efficient and complete combustion. Furthermore, this configuration greatly reduces the risk of equipment clogging.

Figure 7 shows the final subcomponent of the main tubular assembly 2: the second fuel pipe 7. A second-fuel inlet 14 designed to receive a second fuel from an external source is fastened close to a first end of the second fuel pipe 7, preferably by threading or welding, and transversely in relation to the second fuel pipe 7.

A third set of through-holes 15, through which the second fuel can be discharged, is arranged at the second end of the second fuel pipe 7. In the preferred operating mode of the present invention, the second fuel fed through the second-fuel inlet 14 is liquefied petroleum gas (LPG). Near to the third set of through-holes 15, the second fuel pipe 7 also has a set of vanes 16 on the outer surface thereof, which are preferably made of stainless steel and are 3 mm thick.

In a preferred embodiment of the present invention, the second-fuel inlet 14 is a 1/2" stainless steel half-coupling, and the second fuel pipe 7 is a 2" stainless steel pipe (of greater diameter than the first fuel pipe 6), in particular 510 mm long.

The assembly of first fuel pipe 6 and compressed air pipe 5 is inserted coaxially inside the second fuel pipe 7, and said components are then joined together, preferably by screwing with a metal plate, which allows simple assembly and disassembly using screws. Similarly to the first space formed between the first fuel pipe 6 and the compressed air pipe 5, a second space is formed between the internal diameter of the second fuel pipe 7 and the external diameter of the first fuel pipe 6. When the second fuel, preferably LPG, is fed through the second-fuel inlet 14, said fuel travels the length of the second fuel pipe 7 through the second space as far as the third set of through-holes 15 and is discharged therethrough.

Figure 8 shows the tubular housing assembly 4, which has two ends and an external combustion air inlet 17. The external combustion air inlet 17 preferably comprises a flange and a pipe that are welded, and is located closer to the first end of the tubular housing assembly 4. The main body of the tubular housing assembly 4 is a pipe, preferably a 6" stainless steel pipe (of greater diameter than the second fuel pipe 7) and 400 mm long. It should be noted that the internal diameter of the tubular housing assembly 4 must be large enough to receive the set of vanes 16 with some clearance. The tubular housing assembly 4 also has a support flange, preferably located relatively close to the second end, to support the lance 1 when in use in a burner.

The first end of the tubular housing assembly 4 is fastened to a flange 18, preferably by welding, which is fastened, preferably using screws, to another flange that fastens the main tubular assembly 2 and the pilot ignition assembly 3, as shown in Figure 9. When fully assembled, the main tubular assembly 2 runs through the length of the tubular housing assembly 4, preferably coaxially. The compressed air nozzle 9, the fuel nozzle 11 , and the third set of through-holes 15 of the second fuel pipe 7 therefore project beyond the second end of the tubular housing assembly 4. As a result, the first, second and third sets of through- holes 12, 13, 15 are exposed to the environment, with the first set of through-holes 12 being in combination with the external environment by virtue of the holes thereof being aligned with the holes in the second set of through-holes 13. At the other end of the tubular housing assembly 4, the compressed air inlet 8, the first-fuel inlet 10, and the second-fuel inlet 14 are exposed, as is part of the pilot ignition assembly 3.

Finally, Figure 10 shows the lance 1 inserted into a combustion chamber of a burner, supported by the support flange of the tubular housing assembly 4.

The operation of the lance 1 according to the present invention is quite simple and the user can choose whether to use the lance with the first fuel only (preferably tar or diesel), with the second fuel only (preferably LPG), or with both fuels. Compressed air is fed into the compressed air inlet 8 and the first fuel is fed into the first-fuel inlet 10. The compressed air flows through the length of the compressed air pipe 5 and the first fuel flows through the length of the first-fuel pipe 6, through the first space formed between these two pipes. Upon reaching the compressed air nozzle 9, the compressed air is discharged under pressure through the holes of the first set of through-holes 12. The compressed air then comes into contact with the first fuel in the first space and both are discharged through the holes of the second set of through-holes 13 of the fuel nozzle 1 1 , thus forming a fuel mist in the combustion chamber of the burner.

Concomitantly, the set of vanes 16 of the second fuel pipe 7 of the main tubular assembly 2 rotates. This rotation creates a flow of external air that enters through the external combustion air inlet 17 of the tubular housing assembly 4. This air is blown into the combustion chamber of the burner and is consumed during combustion of the fuel mist. If the operation also uses a second fuel, preferably LPG, this fuel is fed into the second-fuel inlet 14 and then flows along the length of the second fuel pipe 7 through the second space formed between said pipe and the first fuel pipe 6. Upon reaching the second end of the second fuel pipe 7, the second fuel is discharged under pressure through the holes of the third set of through-holes 15, and is then fed into the combustion chamber of the burner.

Finally, the pilot ignition assembly 3, which is a substantially tubular lance for conveying fuel ignition means, is able to provide heat. When the lance 1 is assembled, the pilot ignition assembly 3 is located in the space between the internal diameter of the tubular housing assembly 4 and the external diameter of the second fuel pipe 7, which is precisely the space through which the combustion air admitted by rotation of the set of vanes 16 flows. Depending on the requirements of the specific application of the lance 1 , the pilot ignition assembly 3 can be used to provide the pilot flame required to burn the LPG in the burner.

It is clear to the person skilled in the art that all the dimensions and material specifications described above are merely preferred embodiments of the present invention, and that other alternative specifications are perfectly possible within the scope of the design. The manufacture of the equipment that makes up the lance 1 requires simple, inexpensive, and widely used materials such as half-couplings, pipes, and billets, and involves simple manufacturing methods such as turning and welding, as well as tool or abrasion finishing. Thus, the lance 1 according to the present invention can be easily manufactured by person skilled in the art without expending excessive time or resources.

The above description illustrates preferred embodiments of the present invention, but the scope of the present invention is not limited by the examples described or by the figures provided with the application. Other configurations are readily available to the person skilled in the art.