WO2011022847A1 - Burner for generating a hot gas stream - Google Patents

Abstract

The invention relates to a burner (1) for generating a hot gas stream for heating purposes. Said burner (1) comprises a burner jacket (21) and injectors (23, 30), to which forced air is fed and which take in fresh air from the surroundings via one or more intake ports (24) in the burner jacket (21) during normal operation, said fresh air being fed to the combustion zone within the burner (1). The discharge ports of the injectors (23, 30) are covered by the burner jacket (21). Such burners (1) of the invention have significantly lower noise emissions than conventional prior art burners while having the same performance and economic efficiency.

Description

 Burner for generating a hot gas stream

TECHNICAL AREA

 The invention relates to a burner for generating a hot gas stream, and a Heißgaserzeu- ger with the burner according to the preambles of the independent claims. STATE OF THE ART

 For the production of hot gas streams for drying and heating purposes in industry, e.g. For the drying and heating of granulated mineral material in the production of asphalt, burners fired by fossil fuels are generally used, in which the fuel is finely distributed and burned in a stream of combustion air. For the generation of this combustion air stream, a blower driven by electrical energy is usually used, which, depending on size and power, forms a not inconsiderable proportion of the investment and operating costs of such a burner.

 In order to keep the fan and thus the required in operation in addition to the fuel energy demand for electrical energy as low as possible, some of the burners supplied combustion air is partially expanded before injecting them to the combustion zone via injectors and some by means of the injector effect generated in this way sucked additional fresh air from the environment, which is then supplied to the combustion zone together with the expanded air.

In addition to the advantage of lower investment and operating costs arises in these burner designs, however, the disadvantage that the intake of fresh air by means of injectors with a strong noise is why such burners are not usable in many places.

PRESENTATION OF THE INVENTION

 It is therefore the object to provide a burner with injectors for the intake of additional fresh air and a hot gas generator with such a burner available that do not have the disadvantages of the prior art or at least partially avoided.

 This task is done by the burner and the

Hot gas generator according to the independent patent claims.

 According to claim 1, the invention relates in a first aspect to a preferably suitable for heavy oil burner for generating a hot gas stream for heating or drying purposes. The burner comprises a burner jacket and has injectors which are supplied with forced air during normal operation of the burner and suck in fresh air from the environment via one or more suction openings in the burner jacket. During operation, this fresh air mixes within the burner with the blower air expanded via the injectors and is then supplied to the combustion zone. In this case, the burner is designed such that the outlet openings of the injectors are covered by the burner jacket, ie are hidden behind the burner jacket in a side view of the burner.

 Such burners according to the invention have significantly lower noise emissions compared with the burners known from the state of the art for the same performance and economic efficiency.

In a preferred embodiment, the intake openings of the burner jacket are of a single covering device, preferably of a circumferential collar, or of several individual covering devices, For example, individual hood-shaped covers, hidden, so that they are hidden in a side view of the burner behind the cover or the. This makes it possible to achieve a further reduction in noise emissions.

 In this case, it is further preferred if the covering devices are designed in such a way that the intake ambient air, on its way to the outlet openings of the injectors, experiences a deflection of more than 90 °, in particular of approximately 180 °, since this favors a further reduction of the noise emissions.

 Furthermore, in embodiments of the burner according to the invention in which the intake openings of the burner jacket are covered by covering devices, it is preferred that these covering devices be provided with a sound-absorbing lining, whereby a large part of the sound generated by the ejectors when the air blows out is intercepted.

 In a further preferred embodiment, the burner jacket limits a flow channel with an annular cross-section for transporting the fresh air drawn in to the combustion zone, in which a plurality of injectors protrude in the direction of flow. In this case, therefore, the burner jacket forms the outer boundary of an annular flow channel for the combustion air flow formed by the expanded air blown through the injectors and the ambient air sucked in via the suction openings. In addition, it is preferred that the injectors, relative to the circular ring cross-section of the flow channel, enter the flow channel circumferentially uniformly distributed.

This design favors the creation of a uniform stable combustion air flow in the flow channel and at the outlet and allows at the same time a cooling of the burner jacket with this air flow in a structurally simple construction of the burner. It is further preferred that the injectors are arranged on two concentric pitch circles In ^¬, preferably having offset circumferential positions, as this a more even inflow of the blower expanded air is possible in the flow channel.

 In yet another preferred embodiment of the burner, the burner jacket has a substantially circumferentially circumferential suction opening, i. an intake opening which extends over the entire circumference of the burner jacket and is interrupted at most by narrow webs or ribs. Such a suction opening has low pressure losses when flowing through is therefore conducive to good efficiency of the burner.

 In yet another preferred embodiment, the burner is designed such that the outlet openings of the injectors, as seen in the flow direction, are arranged at at least two different axial positions. This ensures a stable air flow even with relatively long flow channels.

 It is further preferred that those injectors whose outlet openings are arranged upstream on top, are fed from a plenum with fan air, while the injectors whose outlet openings are arranged downstream of the aforementioned injectors, fed from a flow channel, which also from the collecting space is supplied with forced air and in which combustion air flows during operation to the combustion zone. To this

It is thus possible to keep the differences in pressure differences across the injectors between upstream and downstream injectors within narrow limits, thereby ensuring stable operation over the entire operating range of the burner. In this case, it is further preferred that the inlet openings of the injectors fed from the flow channel are arranged in the flow channel in such a way that part of the kinetic flow energy of the combustion air flow flowing in this flow channel is converted into pressure energy for expansion in the injectors. In other words, this means that the flow guided in the flow channel experiences no or only a slight deflection for entry into the respective injector, or preferably undergoes a larger deflection only inside the injector.

 In yet another preferred embodiment, the burner has concentrically arranged, preferably annular exit cross-sections for a fuel-carrying air flow and combustion air and is designed such that the outermost of the concentric outlet cross-sections is fed in operation with the intake via the injectors fresh air , As a result, a sheath flow of combustion air is placed around the fuel-carrying flow in operation, which is conducive to a stable combustion zone and complete combustion.

 According to claim 14, a second aspect of the invention relates to a hot gas generator having a

 Combustion chamber, which forms a combustion chamber into which a burner according to the first aspect of the invention opens, such that the combustion chamber in operation surrounds the combustion zone. With such a use of the burner according to the invention for a hot gas generator, the advantages of the invention become particularly clear.

 In a preferred embodiment of the

Hot gas generator has this a plurality of preferably identical burner according to the first aspect of the invention, which open into the combustion chamber, wherein it is further preferred that these on identical axia- len positions with respect to the flow direction of the hot gas generated during operation with the hot gas generator open into the furnace. In this way, hot gas generators according to the invention having virtually any heating power can be provided with a burner size.

BRIEF DESCRIPTION OF THE DRAWINGS

 Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

 1 is a perspective top view obliquely from above of a heavy oil burner according to the invention;

 FIG. 2 shows a vertical section through the heavy oil burner from FIG. 1; FIG. and

 3 shows a perspective sectional view through the burner arrangement of the burner from FIGS. 1 and 2.

WAYS FOR CARRYING OUT THE INVENTION

 A preferred embodiment of the burner according to the invention in the form of a heavy oil burner 1 is shown in FIGS. 1 and 2, once in a perspective plan view and once in a vertical section. As can be seen, the burner basically consists of a single-stage radial fan 2 for providing the combustion air and a burner assembly 3, which are screwed together.

 As can be seen from Fig. 2 in conjunction with Fig. 3, which shows the burner assembly 3 in perspective in section, can be seen in the center of the

Burner assembly 3, a burner lance 4, at the burner exit side or Verbrennungsennungszonenseitigem end a nozzle body 5 with nozzle holes (not shown) is arranged. At its other end, the burner lance 4 is connected to a supply line 20 for heavy oil. Within the burner lance 4, a central bore is present. the one which connects the supply line 20 with the nozzle body 5.

 The burner lance 4 is coaxially surrounded by a first tube 6, which in the region of the outlet of the nozzle bores from the nozzle body 5 has an insert 7, which tapers the tube cross-section in this area. Between the tube 6 with the end arranged in this insert 7 and the burner lance 4 with the associated nozzle body 5, a first annular flow channel 8 is formed, which has its smallest flow cross-section in the region of the outlet of the nozzle holes from the nozzle body 5 and a first Throttle valve 9 is connectable to the outlet side of the blower 2.

 Upstream of the nozzle body 5 in the first flow channel 8 is a spiral guide plate 10, which imparts a twist to the air flowing during operation through the flow channel 8 before it enters the region of the flow channel 8 bounded by the insert 7. The baffle 10 is supported by the burner lance 4 and is firmly connected thereto.

 The first tube 6 is coaxially surrounded by a second tube 12, which in turn is coaxially surrounded by a third tube 16, which has a nozzle-like insert 19 in the region of its burner outlet end. The insert 19 tapers the tube cross-section in this area towards the burner outlet-side end first suddenly and then steadily increasing. Between the second tube 12 with the nozzle ring 14 and the third tube 16 with the insert 19, a second annular flow channel 17 for combustion air is formed. This second flow channel 17 is connected via a second throttle valve 18 with the outlet side of the blower 2.

The insert 19 surrounds the first tube 6 with the insert 7 arranged therein in the area of the outlet-side end of the insert 7 and delimits the in this region between it and the nozzle ring 14 formed second flow channel 17 such that in operation emerging from the second flow channel 17

Combustion air V a sheath flow around the out of the

Insert 7 and thus from the first flow channel 8 emerging and atomized oil carrying air flow Z around forms.

 The third tube 16 is coaxially surrounded by a fourth tube 21, which here forms the claimed burner jacket. Between the third tube 16 and the fourth tube 21, a third annular flow channel 22 is formed. The fourth tube 21 surrounds the third tube 16 in the region of the outlet end of the same such that during operation the exiting from the third flow channel 22 air flow L an envelope flow around the third tube 16 and thus from the second flow channel 17 exiting air flow V forms.

 As can also be seen, the third flow channel 22 is connected via a plurality of injector tubes 23 with a collecting space 25 for combustion air, which is connectable via the second throttle valve 18 with the pressure side of the blower 2. The injector tubes 23 are distributed uniformly over the circumference of the transverse section of the third flow channel 22 on two concentric pitch circles with offset circumferential positions.

 In the area of the injector tubes 23, the fourth tube 21 has a circumferentially substantially circumferential suction opening 24 which connects the third flow channel 22 surrounded by this tube 21 and the outlet sides of the injector tubes 23 to the environment. In this case, the intake opening 24 is dimensioned such that the fourth tube 21 covers the outlets of the injector tubes 23, so these are hidden in the side view under the fourth tube 21.

Downstream of the aforementioned Injektorrohre 23 opens a variety of other injectors 30 in the third flow channel 22, which branch off combustion air from the second flow channel 17 and expand into the third flow channel 22, creating an injector in the third flow channel 22. These injector tubes 30 are uniformly distributed over the circumference of the third flow channel 22. As can also be seen, they branch off the extracted combustion air from the second flow channel 17 at an angle of approximately 40 ° to the flow direction of this flow channel, so that in operation part of the existing flow energy is converted into pressure energy for expansion.

 As can further be seen, the suction opening 24 is covered by a circumferential collar 29 (sophisticated covering device), such that the suction opening 24 is hidden behind the collar 29 in a side view of the burner. As can be seen, in this way the air sucked in from the surroundings via the intake opening 24 is forced on its way to the outlet openings of the injectors 23, 30 by a deflection of approximately 180 °.

 In operation, the burner lance 4 is supplied via a fuel pump (not shown) heavy oil, which is then injected via the nozzle bores of the nozzle body 5 in the first flow channel 8.

 At the same time, air is supplied from the blower 2 to the first flow channel 8 via the first throttle valve 9 and a first plenum 26 and the second flow channel 17 via the second throttle valve 18 and a second plenum 25.

The air flowing in the first flow channel 8 passes through the region in which the spiral baffle 10 is arranged, and then enters as a swirl flow in the region in which the heavy oil is injected via the nozzle bores of the nozzle body 5 in the first flow channel 8. She tears the injected heavy oil with it and then enters as air flow Z with finely divided Schwerölteil ^¬ chen from the insert 7 of the first tube 6 from, to then be burned in the adjoining the burner outlet combustion zone.

 The guided in the second flow channel 17 combustion air is divided into two partial streams. The first partial flow is expanded via the injector tubes 30 into the third flow channel 22, while the second partial flow enters in the region of the outlet-side end of the second flow channel 17 into a swirl body 27 arranged there, which it leaves as swirl flow. Subsequently, the second partial flow enters the nozzle-shaped insert 19, which forms the outlet-side end of the second flow channel 17. He then leaves this as a spirally rotating flow, which forms a sheath flow of combustion air V to the air flow Z exiting from the insert 7 and thus from the first flow channel 8 with the atomized heavy oil contained therein.

 A subset of the amount of combustion air V entering the second plenum 25 via the second throttle valve 18 is expanded via the injector tubes 23 into the third flow channel 22. At the same time, fresh air from the environment is drawn into the third flow channel 22 through the injector effect generated by these injector tubes 23 and injector tubes 30 via the downstream injector tubes 30, which then mixes with the air expanded via the injectors 23, 30 and in the third flow channel 23 continues to flow. At the end of this flow channel 23, this air flow passes through an arrangement of guide ribs 28 before it emerges therefrom, thereby forming a straight-lined envelope flow Z around the spiral envelope flow of combustion air V emerging from the second flow channel 17.

Alternatively or in addition to the heavy oil firing, the burner 1 can also be operated with a fuel gas. ben. As can be seen, a further annular flow channel 13 is formed between the first tube 6 and the second tube 12, which opens into a nozzle ring 14 on the burner outlet side and is connected at its other end to a fuel gas feed line 15. Via this further flow channel 13, fuel gas can be conducted from the fuel gas supply 15 to the nozzle ring 14, for injecting the fuel gas into the combustion zone.

 During operation of the burner, the throttle valves 9, 18 can be adjusted individually such that a desired flame pattern is obtained, optionally with additional adjustment of the axial position of the burner lance 4 and the amount of fuel supplied. If an operation with fuel gas takes place, the supplied fuel gas amount can be adjusted.

 While preferred embodiments of the invention are described in the present application, it should be clearly understood that the invention is not limited to these and may be practiced otherwise within the scope of the following claims.

Claims

1. Burner (1) for generating a hot gas stroines for heating purposes, wherein the burner (1) has a burner jacket (21) and injectors (23, 30) which are fed during normal operation with forced air and via one or more suction ports ( 24) suck in the burner jacket (21) fresh air from the environment, wherein the outlet openings of the injectors (23, 30) from the burner jacket (21) are covered.  2. Burner (1) according to claim 1, wherein the one or more suction openings (24) by a single or more covering devices (29) are covered.  3. burner (1) according to claim 2, wherein the cover device is formed as a circumferential collar (29).  4. Burner (1) according to one of claims 2 to 3, wherein the covering devices (29) are designed in such a way that the air drawn in on its way to the outlet openings of the injectors (23, 30) undergoes a deflection of more than 90 °, in particular of approximately 180 °.  5. Burner (1) according to one of claims 2 to 4, wherein the covering devices (29) are provided with a sound-absorbing lining.  6. Burner (1) according to one of the preceding Claims, wherein the burner jacket (21) defines a flow channel (22) with circular cross-section for the transport of fresh air sucked to the combustion zone, in which viewed in the flow direction, a plurality of injectors (23, 30) protrude, in particular with circumferentially uniform distribution.  7. burner (1) according to claim 6, wherein the Injectors (23) are arranged on two concentric pitch circles, in particular with offset circumferential positions. 8. Burner (1) according to one of the preceding Claims, wherein the burner jacket (21) has a substantially circumferentially circumferential intake opening (24) ^¬ .  9. Burner (1) according to one of the preceding claims, wherein the burner (1) is designed such that the outlet openings of the injectors (23, 30) are arranged as seen in the flow direction at at least two different axial positions.  10. burner (1) according to claim 9, wherein the burner (1) is designed such that the injectors (23) whose outlet openings are arranged upstream to uppermost, fed from a plenum (25) with forced air, while injectors (30 ), whose outlet openings are arranged downstream of these, from a flow channel (17) are fed, which is also fed from the collecting space (25) and combustion air leads to the combustion zone.  11. Burner (1) according to claim 10, wherein the inlet openings of the from the flow channel (17) inspired injectors (30) in such a way in the flow channel (17) are arranged such that in operation a portion of the kinetic flow energy of the combustion air flowing in this flow channel (17) is converted into pressure energy for expansion in the injectors (30).  12. Burner (1) according to one of the preceding Claims, wherein the burner (1) concentrically arranged outlet cross-sections for a fuel-carrying air flow (Z) and one or more combustion air flows (V, L) and is designed such that the outermost outlet cross section in Operation with the means of the injectors (23, 30) sucked air is fed. 13. Burner (1) according to one of the preceding claims, wherein the burner (1) is a heavy oil burner. 14. hot gas generator with a combustion chamber which forms a combustion chamber into which a burner (1) opens according to one of the preceding claims.  15. Hot gas generator according to claim 14, wherein a plurality of in particular identical burners (1) according to one of claims 1 to 13 open into the combustion chamber, in particular at identical axial positions with respect to the flow direction of the hot gas generated during operation with the hot gas generator.