EP0180657A1 - Burner for low-volatility fuels - Google Patents

Abstract

1. Burner (1) for scarcely volatile fuels, having an annular retort space (7), which is at least partially bounded by an inner cylinder (3) and an outer cylinder (6), having a fuel supply line (18, 24) for fuel to the retort space (7), having a combustion chamber (2) within the inner cylinder (3), the combustion chamber case (27) being formed at least partly by the cylinder wall, having at least one outlet gap (8, 9) from the retort space (7) radially outward to an air intake and mixing chamber (14), surrounding the retort space (7) and having a wall (16), which bounds the cylindrical combustion chamber (2) at the face opposite an outlet opening (19) for waste gases and which extends radially further outwards and at the same time forms the end wall of the surrounding air intake and mixing chamber (14), the cylindrical combustion chamber wall (3) reaching almost right up to the wall (16), forming a radially encircling inlet gap (17).

Description

The invention relates to a burner for volatile fuels according to the preamble of claim 1.

A burner is a device for burning a solid, liquid or gaseous fuel. For this purpose, the fuel is brought together with the air required for combustion in the burner. A number of different methods are possible for this. In the parallel flow burner, air and fuel meet in parallel jets at the burner mouth; in the cross flow burner they meet in front of the burner mouth; In the eddy current burner, a good mixing of fuel and air is achieved by swirling.

A number of different methods are also known for supplying the fuel. In an atomizer burner, for example, liquid fuel is introduced finely divided under pressure or by a compressed air or steam jet. With a coal dust burner, finely ground coal dust is blown into the furnace by compressed air.

In the known burners mentioned above when using solid or liquid fuel this, although finely divided or atomized, but still supplied to the combustion chamber and the furnace as a whole. Many solid or liquid fuels, especially petroleum, waste oil or coal, contain a number of non-combustible or poorly combustible components that are undesirable and polluting in the flue gas as solid particles. According to recent medical findings, these particles are said to contain carcinogenic substances.

The invention is also based on the finding that burners for gaseous fuels are normally simpler and more precisely controllable and that the combustion is overall more effective.

The object of the invention is to provide a burner for volatile (liquid or solid) fuels with which the combustion can be carried out in an environmentally friendly and low-pollutant manner and which can also be regulated easily and easily.

This object is achieved in a generic burner with the characterizing features of claim 1.

The basic idea of the invention is to gasify solid or liquid fuels by supplying heat outside the combustion chamber and to supply only the fuel gases thus generated to the combustion chamber. The gasification is carried out so that the fuel hits a part of the hot outer wall of the combustion chamber, is heated there and the combustible gas is expelled from the fuel.

For this purpose, the burner is constructed in such a way that the expediently cylindrical combustion chamber is at least partially surrounded by an annular retort space in which the gasification is to take place. The Brenn opens into the retort room fabric supply line. At least one outlet gap for the exit of the fuel gases formed in the retort chamber leads axially outward from the retort chamber to an air intake and mixing chamber. It has been shown that the suction effect of a chimney through the entire burner is normally sufficient for air intake. An entry gap for the combustible air-gas mixture leads from the mixing chamber to the combustion chamber. The mixture is burned there. The hot exhaust gases exit through a relatively large outlet opening from the combustion chamber in the direction of the chimney and are conducted via a heat exchanger, for example a boiler, to utilize the heat of combustion.

In the burner described above, solid or liquid fuel is supplied to the retort space, where the (partial) gasification of the fuel takes place on the hot outer wall of the combustion chamber. A high proportion of pollutants is therefore no longer contained in the fuel gas and is no longer fed to the combustion process or no longer arises from the combustion. In addition, all advantages of the control and regulation for a gas burner, in particular a simple and precise stepless power control, can be carried out. By using the combustion chamber jacket as a heat source for the gasification in the retort space, the construction of the burner is compact and inexpensive, as well as safe and simple in function and handling.

In a preferred embodiment, the combustion chamber consists of an inner cylinder with annular flanges protruding radially on both end faces. Another outer cylinder lies between these ring flanges, so that a retort space is created which is delimited by the outer wall of the inner cylinder, the inner wall of the outer cylinder and the two ring flanges. According to claim 2, one or two exit gaps for the exit of the fuel gas are structurally simple as a circumferential column formed between the outer and inner cylinders or the outer cylinder and the ring flanges. The gap widths can be easily changed for a basic setting or a power control by mutually moving the cylinders.

It is expressly pointed out that the cylindrical shape of the combustion chamber and the retort space is the most recognized design, both in terms of production technology and of the distribution of the fuel. However, the effect according to the invention is always achieved when a retort space for the gasification is attached directly to the outer combustion chamber jacket, in a heat-transferring manner, regardless of the special shape.

According to claim 3, the air intake for air preheating over already warm parts in the burner or on the heat exchanger is advantageously performed, whereby the mixing and firing is more effective.

According to claim 4, the fuel supply line is expediently guided from above into the retort space. Liquid fuels run off the hot cylinder outer wall of the combustion chamber and are thus distributed for fast and effective gasification. Liquid fuel can, however, also be injected into the retort space under pressure using a pump, possibly also atomized. When burning solid fuels, for example coarse-grained coal, the supply is also conveniently from above, so that the fuel is transported into the retort space by gravity. Solid fuel is expediently charged in batches, with the inflow port or the fuel storage chamber being closed again after each loading in order to avoid incorrect air or gas leakage, which can be done automatically with an automatic loading.

A particularly advantageous embodiment is characterized in claim 5. The inner cylinder or the outer chamber of the combustion chamber is designed to be rotatable. As a result, hot surface areas of the combustion chamber outer jacket are continuously moved into the area of the fuel supply and the gasification point, so that effective gasification and a more uniform temperature load can be achieved. In order to ensure the rotatability of the inner cylinder even at high temperatures, it is necessary to manufacture the highly temperature-stressed parts from refractory material with low thermal expansion. Manufacture from ceramics has proven to be particularly suitable.

The combustion chamber is expediently open at the ends of the inner cylinder, one side being connected to the heat exchanger and the chimney as an exhaust opening. On the other hand, the other side is covered at a distance from a wall that is also the outer wall of the mixing chamber. This creates an entry gap for the combustible gas-air mixture to the combustion chamber. By means of a relative displacement of the combustion chamber cylinder or the cover wall, this inlet gap can easily be adjusted continuously, whereby a continuous, quickly responsive power control is achieved, as claimed in claim 6.

According to claim 7, the inner cylinder is designed to be rotatable, whereby the advantages mentioned in connection with claim 5 are achieved.

According to claim 8, in a further development, a scraper or a milling cutter is attached to the outside of the rotatable inner cylinder, which removes stuck fuel residues which accumulate during gasification. Appropriately, a pipe and a waste container is attached under the scraper, into which the residues fall. The waste bin must be emptied occasionally. When burning solid fuels, a scraper can also be used as the lower limit of the filling chute.

In claim 9, another setting and control option for the burner is given. For this purpose, a gap is provided in the area of the outlet opening for the exhaust gases, which has a connection to the air supply. Afterburning can thus be carried out after the actual burner chamber. It is thus possible to run the combustion in the combustion chamber with the air deficit that is often desired, whereby the afterburning hardly contains any unburned or partially burned fuel residues in the flue gas.

With claim 10 a practically proven construction is claimed, in which the individual parts are loosely assembled. In particular when manufacturing from ceramic material, material stresses can no longer develop as a result, which can otherwise lead to cracks and breaks.

The invention is explained in more detail with the aid of exemplary embodiments, with further details, features and advantages.

• Figur 1 einen Radialschnitt durch einen Brenner
• Figur 2 einen Axialschnitt durch den Brenner Figur 1
• Figur 3 einen Radialschnitt einer zweiten Ausführungsform eines Brenners
• Figur 4 einen Axialschnitt des Brenners nach Figur 3.

Show it:

• 1 shows a radial section through a burner
• 2 shows an axial section through the burner FIG. 1
• Figure 3 shows a radial section of a second embodiment of a burner
• FIG. 4 shows an axial section of the burner according to FIG. 3.

1 and 2 show a burner 1 which contains a cylindrical combustion chamber 2 which is delimited by an inner cylinder 3. From the inner cylinder 3 ring flanges 4 and 5 protrude radially outwards on both end faces. A further outer cylinder 6 is arranged between the ring flanges 4, 5 at a distance from the inner cylinder 3, so that a retort space 7 is formed between the inner and outer cylinders 3, 6 and the ring flanges 4, 5.

Between the outer cylinder 6 and the ring flanges 4, 5 there are two outlet gaps 8, 9 which extend radially outward from the retort space 7. The inner cylinder 3 is fastened to a spoke rim 10, which in turn is connected to a shaft 11. The shaft 11 is held on one side in a bearing bush 12 and is guided to a rotary drive (not shown).

The combustion chamber 2 and the retort chamber 7 are surrounded by a further cylindrical housing 13, which forms the air intake and mixing chamber 14. On the very outside is the cylindrical outer housing 15, with which the burner is fastened, for example, to a boiler.

One side (right side in FIG. 2) of the combustion chamber 2 is covered by a wall 16, leaving an entry gap 17 free. The wall 16 is movable in the direction of the combustion chamber 2, so that the gap width of the inlet gap 17 is variable. Furthermore, the shaft 11 and thus the ring flanges 4, 5 are movable in the axial direction, so that the gap widths of the outlet gaps 8, 9 can also be changed. A fuel supply line 18 (for liquid fuel) leads to the retort space 7 from the outside of the burner 1.

The other side of the combustion chamber 2 (left side in FIG. 2) is open over the entire cylinder diameter as an outlet opening 19 for exhaust gases. The combustion chamber 2 is followed by a cylindrical connection piece 20, which is connected to the downstream heat exchanger, for example a boiler 21 leads. An air gap 22 is left between the inner cylinder 3 and the nozzle 20. The width of this air gap 22 can be changed and adjusted with the aid of a sleeve 23 attached to the cylindrical connection piece 20.

In Figure 1, a filler shaft 24 for solid fuel is also shown, which is vertically offset from the center (to the left). The filling shaft _'24 is covered by a lid 25th The filler shaft is bounded at the bottom by an obliquely positioned scraper 26, which bears against the outside of the inner cylinder 3 (combustion chamber jacket 27). Below the scraper 26 there is a vertical pipe or a shaft 28 which is connected to an emptied waste container 29.

The burner 1 shown has the following function: In the stationary case, d. H. when the burner 1 has been ignited by means known per se, a suction is generated by the chimney (not shown) connected to the boiler 21, which draws air into the mixing chamber 14 via the annular inlet opening 30 along the arrows drawn from there. At the same time, when operating with liquid fuel, it is passed through the fuel supply line 18 into the retort space 7. Due to the already started combustion in the combustion chamber 2, the inner cylinder 3 or the combustion chamber jacket 27 is so hot that the liquid fuel 18 largely gasifies. The gas flows out of the annular outlet gaps 8, 9 into the mixing chamber 14. The exit gap width or which of the exit gaps 8, 9 is open can be adjusted by axially displacing the inner cylinder 3.

In the mixing chamber 14, the fuel gas mixes with the air flowing past and passes through the entry gap 17 into the combustion chamber 2, where the combustion takes place. The width of the entry gap 17 can also be adjusted by moving the wall 16. On the one hand, this is necessary to ensure that the combustion does not already take place in the mixing chamber 14; on the other hand, the gap width selection (within certain limits) enables continuous power control.

The hot exhaust gases then reach the exhaust gas outlet opening 19 via the adjustable air gap 22, and air is additionally drawn in directly from the mixing chamber 14 in this area. If there are still unburned or partially burned gas residues in the exhaust gas from the combustion chamber 2, they are still burned in the nozzle 20.

When operating with solid fuels, they are supplied to the retort chamber 7 not via the fuel supply line 18, but via the filler shaft 24. The granular fuel particles lie against the hot fuel jacket 27, which rotates past the fuel. The residues applied to the combustion chamber shell 27 are scraped off by the scraper 26 (when the shaft 11 or the combustion chamber shell 27 rotates to the right) and fall through the shaft 28 into the waste container 29.

The second embodiment of a burner 1 according to FIGS. 3 and 4 differs only by a few essentially structural changes, so that the same reference numerals are used for the essentially identical parts.

In the embodiment according to FIG. 3 and FIG. 4, only a cylindrical outer housing 15 is provided, so that the air is guided according to the arrows also drawn here. The ring flanges 4, 5 are chosen to be higher in the radial direction and lateral ring flanges 31, 32 are also attached to the outer cylinder 6. There through the exit gaps 8, 9 are longer. There is thus less of a risk of undesired combustion occurring in the retort space 7 due to the entry of incorrect air.

An essential feature of the second embodiment is that the shaft 11, the ring of spokes 10, the ring flanges 4, 5 and the inner cylinder 3 are not a one-piece component, but louder assembled and mutually braced components which engage in grooves and thus a torque-transmitting connection form. Engagement grooves can be seen, for example, at points 33, 34, 35. The clamping sleeve 36 pushed onto the shaft 11 is by suitable, known means, such as nuts, split pin, ect. secured. The aforementioned assembled individual parts are made of ceramic material.

The function of the second embodiment of the burner 1 corresponds to the first embodiment.

In summary, it is found that more environmentally friendly exhaust gases are achieved with the burner according to the invention and that the burner permits simple continuous control within certain limits. Furthermore, problem fuels, such as waste oil, ect. be heated in an environmentally friendly manner.

Claims (10)

1. burner (1) for volatile fuels, with an annular retort space (7) which is at least partially delimited by an inner (3) and outer cylinder (6), with a fuel supply line (18, 24) for fuel to the retort space (7), with a combustion chamber (2) inside the inner cylinder (3), the combustion chamber jacket (27) being formed at least in part by the cylinder wall, with an air intake and mixing chamber (14), with an outlet opening (19) for exhaust gases in the combustion chamber (2),
marked by an air intake and mixing chamber (14) surrounding the outer cylinder (6), at least one outlet gap (8, 9) from the retort chamber (7) axially outwards to the air intake and mixing chamber (14), an entry gap (17) from the air intake and mixing chamber (14) to the combustion chamber (2), the outlet opening (19) for exhaust gases, which lies opposite the inlet gap (17).

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