EP2587148B1 - Secondary combustion chamber with secondary air inlet - Google Patents
Secondary combustion chamber with secondary air inlet Download PDFInfo
- Publication number
- EP2587148B1 EP2587148B1 EP12188466.2A EP12188466A EP2587148B1 EP 2587148 B1 EP2587148 B1 EP 2587148B1 EP 12188466 A EP12188466 A EP 12188466A EP 2587148 B1 EP2587148 B1 EP 2587148B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- secondary air
- flow
- combustion chamber
- air nozzles
- duct
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Not-in-force
Links
- 238000002485 combustion reaction Methods 0.000 title claims description 103
- 239000000567 combustion gas Substances 0.000 claims description 73
- 238000002156 mixing Methods 0.000 claims description 39
- 238000002347 injection Methods 0.000 claims description 37
- 239000007924 injection Substances 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 8
- 239000007789 gas Substances 0.000 description 18
- 239000002028 Biomass Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000010954 inorganic particle Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000443 aerosol Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
- F23G5/14—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion
- F23G5/16—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion in a separate combustion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C3/00—Combustion apparatus characterised by the shape of the combustion chamber
- F23C3/006—Combustion apparatus characterised by the shape of the combustion chamber the chamber being arranged for cyclonic combustion
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C7/00—Combustion apparatus characterised by arrangements for air supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/32—Incineration of waste; Incinerator constructions; Details, accessories or control therefor the waste being subjected to a whirling movement, e.g. cyclonic incinerators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
- F23G7/10—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2202/00—Combustion
- F23G2202/10—Combustion in two or more stages
- F23G2202/103—Combustion in two or more stages in separate chambers
Definitions
- the invention relates to secondary combustion chamber according to the preamble of claim 1 and a method for operating a secondary combustion chamber according to claim 9.
- Secondary combustion chambers serve for the afterburning of a combustion gas stream, which is produced by combustion in a primary combustion chamber.
- Biomass combustion devices therefore usually have a primary combustion chamber and a secondary combustion chamber.
- the primary combustion chamber is also called filling space during log burning.
- biomass z.
- a thermochemical conversion of the biomass into the essential combustion products CO 2 and H 2 O takes place in three combustion phases with increasing degree of oxidation.
- the biomass is heated and dried.
- Especially in a combustion start and a stop of the combustion are released in the biomass combustion very many inorganic particles, such as K 2 O, CaO, K 2 SO 4 , K 2 CO 3 .
- secondary combustion chambers are used to purify the combustion gas flow in order to carry out a fourth combustion phase.
- the emerging from the primary combustion hot combustion gas flow is introduced for this purpose in the secondary combustion chamber.
- the secondary combustion chamber Secondary air supplied to nachverbines the combustion gas flow and so to reduce the number of particles in the combustion gas stream. Ignition is usually not necessary because the combustion gas flow is so hot that it self-ignites when oxygen is supplied. In order to achieve good afterburning, it is necessary to mix the air and thus the oxygen well with the combustion gas flow, because only then can the particles oxidize.
- the prior art provides tubular secondary combustion chambers, in which the secondary air is introduced tangentially.
- the combustion gas stream is introduced axially into the secondary combustion chamber. Due to the tangential introduction of the secondary air creates a gas vortex in the secondary combustion chamber, which is why such secondary combustion chambers are also referred to as cyclone combustion chambers.
- This gas vortex is intended to mix the combustion gas stream with the secondary air.
- the disadvantage is that, inter alia, forms an axial core flow in the center of the vortex, in which no secondary air passes. The proportion of the combustion gas flow in the core flow is thus not post-combusted and the unburned particles pollute the environment.
- the cyclone combustion chamber is quite bulky, to complete the secondary combustion can complete.
- the secondary combustion chamber has a flow channel.
- the combustion gas is passed from the primary chamber coming into another combustion chamber.
- the secondary air is introduced tangentially and transversely to the combustion gas flow in this flow channel, the latter being cylindrical.
- the GB 2199929 A discloses an afterburner for exhaust gases having means for causing a helical movement of the exhaust gases within the afterburner chamber.
- a pre-combustion chamber arranged upstream of the after-combustion chamber serves to mix contaminated exhaust gases with air.
- the pre-combustion chamber has a triangular cross-section, the air flowing through a series of parallel air nozzles along a first edge of the triangular preburn and the exhaust gases through a series of parallel exhaust nozzles along a second edge not parallel to each other in the pre-combustion chamber, while the Air-exhaust gas mixture flows out through a series of parallel mixture nozzles along a third edge of the pre-combustion chamber and flows into the afterburner.
- the US 3875874 A shows an afterburner for the combustion of exhaust gases with a refractory chamber, which is divided into a first and a second region.
- An oxidant flows into the turbulent exhaust gas through a plurality of spaced-apart, circumferentially and circumferentially spaced along the refractory chamber arranged air pipes, which are perpendicular to the exhaust gas flow or inclined in the direction of the flowing exhaust gas.
- the aim of the invention is therefore to overcome the aforementioned disadvantages of the prior art, and to provide a secondary combustion chamber with a flow channel and a method which allow improved mixing of a combustion gas stream with secondary air, in order to optimize afterburning, especially in a biomass combustion device to reach.
- a secondary combustion chamber should be simple, compact, safe in operation and low maintenance, and have low production costs.
- the invention relates to a secondary combustion chamber with a flow channel for post combustion of a combustion gas stream by mixing with secondary air, wherein the flow channel defines a flow direction for the combustion gas flow, wherein the flow channel has a cross section with a long side and a short side, wherein at least two secondary air nozzles for injecting the secondary air lead into the flow channel, which within a Eindüsungsabterrorisms the Flow channels are arranged and not parallel to the flow direction aligned Eindüsungslegien.
- the long side of two opposite long channel walls is formed, wherein at least two secondary air nozzles are arranged on the first long channel wall and at least two secondary air nozzles on the second long channel wall.
- the secondary air nozzles arranged on the first long channel wall are in each case offset by an offset distance oriented transversely to the flow direction to the secondary air nozzles arranged on the second long channel wall.
- a flow vortex is then formed between two offset secondary air nozzles which is set in rotation from two sides.
- the injection of secondary air with two secondary air nozzles in the injection section allows the formation of several adjacent flow vortices in the flow channel.
- these vortices continue essentially parallel in the flow channel.
- smaller but smaller vertebrae can form.
- One of the main parameters of a clean combustion - namely the mixing of the combustion gas with the secondary air - can be significantly improved. Accordingly, the gas phase oxidation increases and the emission of hydrocarbon, carbon monoxide and unburned particles decreases. Thus, for example, a clean combustion of biomass can be done.
- the secondary combustion chamber can be made smaller overall due to the improved and very rapid mixing. Among other things, this reduces the required installation space and material costs. It is also particularly advantageous that a much faster start-up phase can be realized by a smaller storage mass in the secondary combustion chamber.
- the combustion gases thus reach a temperature in the secondary combustion chamber, in which afterburning is possible, particularly fast.
- the optimum temperature is above 700 ° C. Emissions during the start-up phase are thus avoided.
- the secondary air injection according to the invention requires at most a small amount of energy, e.g. through a flow generator such as a fan.
- the secondary air nozzles can be easily constructed, so that the secondary combustion chamber is low maintenance, safe in operation and low manufacturable.
- the formation of the vortices is particularly good when the at least two secondary air nozzles are located approximately equidistant along the flow direction.
- An embodiment of the invention therefore provides that two adjacent secondary air nozzles have a maximum distance in the flow direction to each other, which is twice the length of the short side of the flow channel cross-section. In this way it can be prevented that one of the flow vortices spreads over the entire flow cross-section of the flow channel, because its expansion is blocked (limited) by an adjacent flow vortex.
- the flow vortices can also be formed with an equal intensity so that none of the vortices dominates or overlaps the adjacent vortices. Thus, as far as possible homogeneous, as well as uniformly formed adjacent flow vortexes can be realized.
- the secondary air nozzles are actually arranged lying in the same direction along the direction of flow.
- the secondary air nozzles should be arranged at the same height along the flow direction, so that they can be cut by a single plane perpendicular to the flow direction. In this way, none of the vortices can propagate over the entire flow cross-section of the flow channel, because its expansion is always, i. already from the time of injection of the secondary air, blocked by an adjacent flow vortex.
- the injection directions are aligned at least approximately perpendicular to the flow direction. Up to 30 degrees deviation from the vertical lead to a good formation of the flow vortex. The more perpendicular the injection direction is aligned, the higher rotational speeds of the flow vortex can be achieved. In addition, there is a shear between the combustion gas flow and the secondary air flow, which greatly improves the mixing.
- an embodiment of the invention is of particular advantage, in which the flow channel extends in the direction of flow to the injection section having subsequent mixing section.
- the vertebrae should be able to continue parallel and adjacent to each other. Therefore, the mixing section should have no or only slight directional and / or cross-sectional changes.
- the length of the mixing section should be adapted to the flow rates of the secondary air and the combustion gas flow, because of this depends decisively on how far the flow vortex can continue. Friction, secondary vortices and the like weaken the flow vortices with increasing distance from the injection section.
- the mixing section should be at least three times as long as the length of the short side of the flow channel. Thus, the mixing section ensures that the flow vortices lead to a maximum mixing of the combustion gas flow with secondary air. The emissions are correspondingly low.
- the mixing of the combustion gas flow with secondary air is further improved in one version of the invention in that the short side of two opposite short channel walls is formed, wherein at least one of the short channel walls is curved outwards.
- the formation of a domed short outer wall allows a circular flow vortex to rotate along the entire short wall. There is no linear flow in a corner between the short channel wall and a long channel wall into which the flow vortex could not reach. Thus, no unburned combustion gas can move through the flow channel here.
- the at least one short channel wall is curved in a semicircular outward direction.
- the long side has a length (a) and the short side has a length (b), wherein the length (a) of the long side approximately multiplies the length (b) of the short side with the number of secondary air nozzles minus one.
- each vortex can be rotated in two directions by secondary air in rotation.
- the secondary air nozzles should be evenly distributed over the long side offset by a constant offset distance. That is to say, for example, that two secondary air nozzles arranged on one of the channel walls have a transversely to the flow direction spaced from each other, which corresponds to twice the offset distance. In each case centrally located between the secondary air nozzles on one of the long channel walls then opposite to the other channel wall another secondary air nozzle.
- the length (a) of the long side should only be approximately equal to the length (b) of the short side multiplied by the number of secondary air nozzles minus one, because the vortexes can easily be easily elliptically formed. Therefore, the length (a) can also deviate from the target value by up to half the length (b) of the short side, without suffering great disadvantages. Too much elliptical formation will result in more shear in the gas stream, which may also result in positive mixing effects, but ultimately will cause an undesirably faster decay of the rotation.
- the invention develops its full potential of mixing the combustion gas stream with the secondary air when at least four secondary air nozzles, but preferably at least six secondary air nozzles open into the flow channel. Although two or three secondary air nozzles can be produced more cheaply, the additional costs per secondary air nozzle remain within the limits. Regardless of the number of secondary air nozzles, these can be fed by a single flow generator with secondary air.
- the improved mixing is based on a higher number of secondary air nozzles, in particular on the ratio of central flow vortex to flow vortex, which adjoin the short channel walls. The central flow vortices collide on two sides with adjacent vortices, which intensifies mixing.
- an embodiment of the invention is of particular advantage, in which the flow channel opens into a combustion chamber, wherein the combustion chamber is preferably a cyclone combustion chamber.
- the combustion chamber is preferably a cyclone combustion chamber.
- the rotational speed of the flow vortices decreases, until hardly any mixing of the combustion gas with secondary air is achieved.
- a change in the flow direction can be brought about and the Mixing of the combustion gas stream with the remaining secondary air, as well as the secondary combustion will be continued.
- the remaining secondary air is already well distributed within the combustion gas stream, before the latter ever flows into the combustion chamber. Accordingly, the combustion chamber can be made relatively small, since the afterburning proceeds faster.
- Particularly advantageous is the use of a cyclone combustion chamber, in which the introduced gas flow through rotation about an axis and associated friction, shear and the like can again be thoroughly mixed and post-combusted.
- the arrangement of the flow channel to the cyclone combustion chamber is preferably eccentric, possibly also tangential, and not parallel to the axis of rotation of the cyclone combustion chamber.
- the cyclone combustion chamber itself should be rotationally symmetrical about the axis of rotation.
- the secondary combustion chamber can be made smaller overall due to the improved and very rapid mixing. Among other things, this reduces the required installation space and material costs. It is also particularly advantageous that a much faster start-up phase can be realized by a smaller storage mass in the secondary combustion chamber.
- the combustion gases thus reach a temperature in the secondary combustion chamber, in which afterburning is possible, particularly fast.
- the optimum temperature is above 700 ° C. Emissions during the start-up phase are thus avoided.
- the introduction of the secondary air according to the invention requires at most a small amount of energy, e.g. through a flow generator such as a fan.
- the secondary air nozzles can be simple in construction, so that the method with a low-maintenance secondary combustion chamber is feasible, which is also safe in operation and low manufacturable.
- An important alternative method of the invention provides that the injection speed of the secondary air is at least half as large and at most four times as large as the flow velocity of the combustion gas. As a result, stable flow vortices can be formed, which lead to a good mixing of the combustion gas with secondary air.
- Fig. 1 shows a cross section through a secondary combustion chamber, and in particular a sectional view EE, as shown in FIG. 3 is characterized by the flow channel 1 of the secondary combustion chamber.
- the flow channel 1 is used for the afterburning of a combustion gas stream G by mixing with secondary air L.
- the flow channel 1 is initially a flow direction for the combustion gas stream G, in the direction of the combustion gas G moves at a flow velocity v.
- водородн ⁇ е nozzles 11, 12, 13, 14 open for the injection of the secondary air L into the flow channel 1. These are all arranged within an injection section 2 of the flow channel 1.
- the secondary air nozzles 11, 12, 13, 14 are all cut from the plane E-E and are therefore all the same along the flow channel 1. Furthermore, they have not parallel to the flow direction R aligned Eindüsungslegien R1, R2, R3, R4. Rather, the Eindüsungslegien R1, R2, R3, R4 are aligned perpendicular to the flow direction of the combustion gas G.
- the flow channel 1 has a cross section with a long side 5 and a short side 6.
- the short side 6 is formed by two opposite short channel walls 61, 62, which are both arched outwards. In particular, these are curved semicircular outwards.
- the long side 5 has a length a and the short side 6 has a length b, the length a of the long side 5 being approximately equal to the length b of the short side 6 multiplied by the number of secondary air nozzles 11, 12, 13, 14 minus one , That is, in the illustrated embodiment, the long side 5 has a length a which is about three times as long as the length b of the short side 6.
- the long side 5 is formed by two opposite long channel walls 51, 52, wherein two secondary air nozzles 12, 14 are arranged on the first long channel wall 51 and two secondary air nozzles 11, 13 on the second long channel wall 52.
- two secondary air nozzles 12, 14 are arranged on the first long channel wall 51 secondary air nozzles 12, 14 each offset by an aligned transversely to the flow direction of the combustion gas G offset distance c to the arranged on the second long channel wall 52 secondary air nozzles 11, 13 are arranged.
- the distance e between two arranged on one side secondary air nozzles 11, 13 or 12, 14 is equal to twice the offset distance c.
- the secondary air nozzles 11, 14 closest to the short channel walls 61, 62 are not arranged entirely on the outside, but they have a distance d to the outermost point of the short channel walls 61, 62.
- the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G.
- this can the cross-sectional areas of the flow channel 1 and the cumulative cross-sectional area of the secondary air nozzles 11, 12, 13, 14 are matched to one another.
- Fig. 2 also shows a cross section through a secondary combustion chamber, and in particular a sectional view EE as shown in FIG. 3 is characterized by the flow channel 1 of the secondary combustion chamber.
- the flow channel 1 is used for the afterburning of a combustion gas stream G by mixing with secondary air L.
- the flow channel 1 is initially a flow direction for the combustion gas stream G, in the direction of the combustion gas G moves at a flow velocity v.
- втори ⁇ ное nozzles 11, 12, 13, 14, 15, 16 open for the injection of the secondary air L into the flow channel 1. These are all arranged within an injection section 2 of the flow channel 1.
- the secondary air nozzles 11, 12, 13, 14, 15, 16 are all cut from the plane EE and are therefore all the same along the flow channel 1. Furthermore, they have not aligned parallel to the flow direction R injection directions R1, R2, R3, R4, R5 , R6 on. Rather, the Eindüsungslegien R1, R2, R3, R4, R5, R6 are aligned perpendicular to the flow direction of the combustion gas G.
- the flow channel 1 has a cross section with a long side 5 and a short side 6.
- the short side 6 is formed by two opposite short channel walls 61, 62, which are both arched outwards. In particular, these are curved semicircular outwards.
- the long side 5 is formed by two opposite long channel walls 51, 52, wherein two secondary air nozzles 13, 15 are arranged on the first long channel wall 51 and two secondary air nozzles 12, 14 on the second long channel wall 52.
- the remaining two secondary air nozzles 11, 16 are each arranged on one of the short channel walls 61, 62.
- secondary air nozzle 16 opens tangentially into the semicircular curvature of the second short channel wall 62.
- secondary air nozzle 16 is also arranged completely outside, so that there is no distance to the outermost point of the second short channel wall 62.
- Secondary air nozzle 11 opens eccentrically, but not tangentially in the semicircular curvature of the first short channel wall 61 and is not aligned perpendicular to the long channel walls 51, 52.
- the arranged on the first long channel wall 51 secondary air nozzles 12, 14 and disposed on the second short channel wall 62 Sekundär Kunststoffdüse 16 are each offset by an aligned transversely to the flow direction of the combustion gas G offset distance to the arranged on the second long channel wall 52 secondary air nozzles 13, 15 and arranged on the first short channel wall 61 secondary air nozzle 11.
- the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G.
- Figure 3 shows a secondary combustion chamber 100 with a flow channel 1 for post combustion of a combustion gas stream G by means of mixing with secondary air L.
- the flow channel 1 a flow direction R for the combustion gas flow G before.
- the flow channel 1 has a cross section with a long side and a short side and on the observer facing side open two secondary air nozzles 11, 12 for injecting the secondary air L in the flow channel 1.
- the secondary air nozzles 11, 12 are within a Eindüsungsabêts 2 of the flow channel 1 arranged and have not parallel to the flow direction R aligned Eindüsungsraumen. They are arranged parallel to one another in the direction of flow R, or lie uniformly along the flow channel 1. Thus, they can be cut perpendicularly to the flow direction R from a single plane EE.
- the flow channel 1 has a mixing section M adjoining the injection section 2 in the flow direction R. With this, the flow channel 1 finally opens into a combustion chamber 102 designed as a cyclone combustion chamber. In particular, the flow channel 1 opens transversely to the axis of rotation of the cyclone combustion chamber in this. Whether tangential and / or eccentric is not visible in the figure.
- a combustion gas G produced in a primary chamber 101 can now be introduced into the flow channel 1 through an inlet opening 3 with a flow velocity v G oriented in the flow direction R.
- secondary air L with an injection speed v L through the secondary air nozzles 11, 12 in the flow channel 1 can be introduced.
- parallel flow vortices form in the Flow channel 1 and continue in the mixing section M parallel.
- the rotational speed of the flow vortices decreases.
- the combustion gas G leaves well mixed with secondary air L, the flow channel 1 through an outlet opening 4 and flows into the combustion chamber 102 a.
- the combustion gas G can be burned. This is particularly dependent on the temperature of the combustion gas G, which increases rapidly after a burner start due to the small volumes of the secondary combustion chamber 100. If the combustion gas G exceeds a certain temperature, it spontaneously ignites when it is enriched with secondary air L.
- the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G.
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- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
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Description
Die Erfindung betrifft Sekundärbrennkammer nach dem Oberbegriff des Patentanspruches 1 und ein Verfahren zum Betrieb einer Sekundärbrennkammer nach Anspruch 9.The invention relates to secondary combustion chamber according to the preamble of
Sekundärbrennkammern dienen der Nachverbrennung eines Verbrennungsgasstroms, der durch Verbrennung in einer Primärbrennkammer entsteht.Secondary combustion chambers serve for the afterburning of a combustion gas stream, which is produced by combustion in a primary combustion chamber.
Bei einer Verbrennung von Brennstoff in einer Verbrennungseinrichtung werden unter anderem gasförmige und/oder staubförmige, organische oder anorganische Komponenten (mineralische Aerosole) aus dem Brennstoff freigesetzt, die gemeinsam mit Verbrennungsabgas einen Verbrennungsgasstrom bilden. Die Verbrennung von Biomasse ist diesbezüglich besonders kritisch.In a combustion of fuel in a combustion device, among other gaseous and / or dust-like, organic or inorganic components (mineral aerosols) are released from the fuel, which together with combustion exhaust gas form a combustion gas stream. The combustion of biomass is particularly critical in this regard.
Biomasseverbrennungseinrichtungen weisen deshalb meist eine Primärbrennkammer und eine Sekundärbrennkammer auf. Die Primärbrennkammer wird bei der Scheitholzverbrennung auch Füllraum genannt. In die Primärbrennkammer wird Biomasse, z. B. Pellets, Scheitholz oder andere Feststoffe, sowie Primärluft eingebracht und wenigstens beim Verbrennungsstart erfolgt eine Zündung. Schließlich erfolgt eine thermochemische Umsetzung der Biomasse in die wesentlichen Verbrennungsprodukte CO2 und H2O in drei Verbrennungsphasen mit zunehmendem Oxidationsgrad. Zunächst wird die Biomasse aufgeheizt und getrocknet. In Phase zwei erfolgt die pyrolytische Zersetzung und anschließend kommt es zur Vergasung. Vor allem bei einem Verbrennungsstart und einem Stopp der Verbrennung (Brennerstart, Brennerstopp) werden bei der Biomasseverbrennung sehr viele anorganische Partikel freigesetzt, so zum Beispiel K2O, CaO, K2SO4, K2CO3. Diese schaden der Umwelt. Aber auch während einer länger andauernden Verbrennung ist der Anteil anorganischer Partikel in einem aus der Primärbrennkammer austretenden Verbrennungsgasstrom höher als bei einer Gas- oder Ölverbrennung.Biomass combustion devices therefore usually have a primary combustion chamber and a secondary combustion chamber. The primary combustion chamber is also called filling space during log burning. In the primary combustion chamber biomass, z. As pellets, logs or other solids, as well as primary air introduced and at least the combustion start is an ignition. Finally, a thermochemical conversion of the biomass into the essential combustion products CO 2 and H 2 O takes place in three combustion phases with increasing degree of oxidation. First, the biomass is heated and dried. In phase two, the pyrolytic decomposition and then it comes to gasification. Especially in a combustion start and a stop of the combustion (burner start, burner stop) are released in the biomass combustion very many inorganic particles, such as K 2 O, CaO, K 2 SO 4 , K 2 CO 3 . These harm the environment. But even during a prolonged combustion, the proportion of inorganic particles in a combustion gas stream emerging from the primary combustion chamber is higher than in the case of gas or oil combustion.
Zur Reinigung des Verbrennungsgasstroms kommen deshalb unter anderem Sekundärbrennkammern zum Einsatz, um eine vierte Verbrennungsphase durchzuführen. Diese umfasst eine abschließende homogene Gasphasenoxidation. Der aus der Primärbrennkammer austretende heiße Verbrennungsgasstrom wird hierfür in die Sekundärbrennkammer eingeleitet. Zusätzlich wird der Sekundärbrennkammer Sekundärluft zugeführt, um den Verbrennungsgasstrom nachzuverbrennen und so die Partikelanzahl im Verbrennungsgasstrom zu verringern. Eine Zündung ist üblicherweise nicht notwendig, da der Verbrennungsgasstrom so heiß ist, dass sich dieser bei einer Zuführung von Sauerstoff selbst entzündet. Um eine gute Nachverbrennung zu erreichen, ist es notwendig, die Luft und somit den Sauerstoff gut mit dem Verbrennungsgasstrom zu durchmischen, denn nur so können die Partikel oxidieren.Therefore, among other things, secondary combustion chambers are used to purify the combustion gas flow in order to carry out a fourth combustion phase. This includes a final homogeneous gas phase oxidation. The emerging from the primary combustion hot combustion gas flow is introduced for this purpose in the secondary combustion chamber. In addition, the secondary combustion chamber Secondary air supplied to nachverbrennen the combustion gas flow and so to reduce the number of particles in the combustion gas stream. Ignition is usually not necessary because the combustion gas flow is so hot that it self-ignites when oxygen is supplied. In order to achieve good afterburning, it is necessary to mix the air and thus the oxygen well with the combustion gas flow, because only then can the particles oxidize.
Hierfür sieht der Stand der Technik unter anderem rohrförmige Sekundärbrennkammern vor, in welche die Sekundärluft tangential eingeleitet wird. Dies wird beispielsweise in
Weiterhin ist aus dem Stand der Technik bekannt, dass die Sekundärbrennkammer einen Strömungskanal aufweist. Durch diesen wird das Verbrennungsgas von der Primärkammer kommend in eine weitere Brennkammer geleitet. Gleichzeitig wird die Sekundärluft tangential und quer zum Verbrennungsgasstrom in diesen Strömungskanal eingeleitet, wobei letzterer zylindrisch ist. So entsteht bereits im Strömungskanal ein Zyklonwirbel bestehend aus Verbrennungsgas und Sekundärluft. Dies ermöglicht, die Sekundärbrennkammer insgesamt kleiner auszubilden, da schon am Eintritt in die Brennkammer eine Durchmischung im Strömungskanal erfolgt ist. Entsprechend startet die Nachverbrennung sehr früh, insbesondere schon im Strömungskanal.Furthermore, it is known from the prior art that the secondary combustion chamber has a flow channel. Through this, the combustion gas is passed from the primary chamber coming into another combustion chamber. At the same time, the secondary air is introduced tangentially and transversely to the combustion gas flow in this flow channel, the latter being cylindrical. This creates already in the flow channel a cyclone vortex consisting of combustion gas and secondary air. This makes it possible to make the secondary combustion chamber smaller overall, since a mixing in the flow channel has already taken place at the inlet to the combustion chamber. Accordingly, the afterburning starts very early, especially in the flow channel.
Nachteilig ist jedoch nach wie vor, dass eine solche Sekundärbrennkammer verhältnismäßig groß ist, dementsprechend Bauraum benötigt und erhöhte Materialkosten aufweist. Außerdem enthält der Verbrennungsgasstrom auch nach der Nachverbrennung in einer solchen Sekundärbrennkammer noch vermeidbare Emissionen wie Kohlenwasserstoffe, Kohlenmonoxid und unverbrannte Partikel.The disadvantage, however, is still that such a secondary combustion chamber is relatively large, accordingly requires space and has increased material costs. In addition, even after afterburning in such a secondary combustion chamber, the combustion gas stream still contains avoidable emissions such as hydrocarbons, carbon monoxide and unburned particles.
Die
Die
Ziel der Erfindung ist es deshalb, die genannten Nachteile des Standes der Technik zu überwinden, und eine Sekundärbrennkammer mit einem Strömungskanal sowie ein Verfahren zu schaffen, die eine verbesserte Durchmischung eines Verbrennungsgasstroms mit Sekundärluft ermöglichen, um eine optimierte Nachverbrennung, insbesondere in einer Biomasseverbrennungseinrichtung, zu erreichen. Für die Durchmischung soll hierbei möglichst wenig Energie aufgewandt werden. Zusätzlich sollte die Sekundärbrennkammer einfach aufgebaut, kompakt, sicher im Betrieb und wartungsarm sein, sowie geringe Herstellkosten haben.The aim of the invention is therefore to overcome the aforementioned disadvantages of the prior art, and to provide a secondary combustion chamber with a flow channel and a method which allow improved mixing of a combustion gas stream with secondary air, in order to optimize afterburning, especially in a biomass combustion device to reach. For the mixing, as little energy as possible should be used. In addition, the secondary combustion chamber should be simple, compact, safe in operation and low maintenance, and have low production costs.
Erfindungsgemäß wird dies mit den Merkmalen der Patentansprüche 1 und 9 gelöst. Vorteilhafte Weiterbildungen sind den jeweiligen Unteransprüchen zu entnehmen.This is achieved with the features of
Die Erfindung betrifft eine Sekundärbrennkammer mit einem Strömungskanal zur Nachverbrennung eines Verbrennungsgasstroms mittels Durchmischung mit Sekundärluft, wobei der Strömungskanal eine Strömungsrichtung für den Verbrennungsgasstrom vorgibt, wobei der Strömungskanal einen Querschnitt mit einer langen Seite und einer kurzen Seite hat, wobei wenigstens zwei Sekundärluftdüsen zur Eindüsung der Sekundärluft in den Strömungskanal münden, welche innerhalb eines Eindüsungsabschnitts des Strömungskanals angeordnet sind und nicht parallel zur Strömungsrichtung ausgerichtete Eindüsungsrichtungen aufweisen.The invention relates to a secondary combustion chamber with a flow channel for post combustion of a combustion gas stream by mixing with secondary air, wherein the flow channel defines a flow direction for the combustion gas flow, wherein the flow channel has a cross section with a long side and a short side, wherein at least two secondary air nozzles for injecting the secondary air lead into the flow channel, which within a Eindüsungsabschnitts the Flow channels are arranged and not parallel to the flow direction aligned Eindüsungsrichtungen.
Erfindungsgemäß ist die lange Seite von zwei gegenüberliegenden langen Kanalwänden ausgebildet, wobei wenigstens zwei Sekundärluftdüsen an der ersten langen Kanalwand und wenigstens zwei Sekundärluftdüsen an der zweiten langen Kanalwand angeordnet sind. Durch eine solche gegenüberliegende Anordnung der Sekundärluftdüsen sind die Strömungswirbel besser ausbildbar, da in beide Richtungen zwischen den langen Kanalwänden Sekundärluft eingedüst wird.According to the invention, the long side of two opposite long channel walls is formed, wherein at least two secondary air nozzles are arranged on the first long channel wall and at least two secondary air nozzles on the second long channel wall. By such an opposing arrangement of the secondary air nozzles, the flow vortices are better formed, since in both directions between the long channel walls secondary air is injected.
Hierbei sind die an der ersten langen Kanalwand angeordneten Sekundärluftdüsen erfindungsgemäß jeweils versetzt um einen quer zur Strömungsrichtung ausgerichteten Versatzabstand zu den an der zweiten langen Kanalwand angeordneten Sekundärluftdüsen angeordnet. Zwischen zwei versetzt gegenüberliegenden Sekundärluftdüsen bildet sich dann jeweils ein Strömungswirbel aus, der von zwei Seiten in Rotation versetzt wird.In this case, according to the invention, the secondary air nozzles arranged on the first long channel wall are in each case offset by an offset distance oriented transversely to the flow direction to the secondary air nozzles arranged on the second long channel wall. In each case, a flow vortex is then formed between two offset secondary air nozzles which is set in rotation from two sides.
Das Eindüsen von Sekundärluft mit zwei Sekundärluftdüsen in dem Eindüsungsabschnitt ermöglicht die Ausbildung mehrerer benachbarter Strömungswirbel im Strömungskanal. Insbesondere setzen sich diese Wirbel im Wesentlichen parallel im Strömungskanal fort. In der Grenzzone zwischen zwei Wirbeln können sich weitere jedoch kleinere Nebenwirbel ausbilden. Einer der Haupteinflussparameter einer sauberen Verbrennung - nämlich die Durchmischung des Verbrennungsgases mit der Sekundärluft - kann so erheblich verbessert werden. Entsprechend steigt die Gasphasenoxidation und die Emission von Kohlenwasserstoff, Kohlenmonoxid und unverbrannten Partikeln sinkt. Mithin kann so zum Beispiel eine saubere Verbrennung von Biomasse erfolgen.The injection of secondary air with two secondary air nozzles in the injection section allows the formation of several adjacent flow vortices in the flow channel. In particular, these vortices continue essentially parallel in the flow channel. In the border zone between two vertebrae, however, smaller but smaller vertebrae can form. One of the main parameters of a clean combustion - namely the mixing of the combustion gas with the secondary air - can be significantly improved. Accordingly, the gas phase oxidation increases and the emission of hydrocarbon, carbon monoxide and unburned particles decreases. Thus, for example, a clean combustion of biomass can be done.
Zudem ist die Sekundärbrennkammer durch die verbesserte und sehr schnelle Durchmischung insgesamt kleiner ausbildbar. Dies verringert unter anderem den benötigten Bauraum und Materialkosten. Besonders vorteilhaft ist dabei zudem, dass durch eine kleinere Speichermasse in der Sekundärbrennkammer eine wesentlich schnellere Anfahrphase realisierbar ist. Die Verbrennungsgase erreichen so besonders schnell eine Temperatur in der Sekundärbrennkammer, bei der eine Nachverbrennung möglich ist. Die optimale Temperatur liegt hierbei oberhalb von 700 °C. Emissionen in der Anfahrphase werden somit vermieden.In addition, the secondary combustion chamber can be made smaller overall due to the improved and very rapid mixing. Among other things, this reduces the required installation space and material costs. It is also particularly advantageous that a much faster start-up phase can be realized by a smaller storage mass in the secondary combustion chamber. The combustion gases thus reach a temperature in the secondary combustion chamber, in which afterburning is possible, particularly fast. The optimum temperature is above 700 ° C. Emissions during the start-up phase are thus avoided.
Die erfindungsgemäße Eindüsung der Sekundärluft erfordert höchstens eine geringe Energiemenge, z.B. durch einen Strömungserzeuger wie ein Gebläse. Die Sekundärluftdüsen können dabei einfach aufgebaut sein, sodass die Sekundärbrennkammer wartungsarm, sicher im Betrieb und günstig fertigbar ist.The secondary air injection according to the invention requires at most a small amount of energy, e.g. through a flow generator such as a fan. The secondary air nozzles can be easily constructed, so that the secondary combustion chamber is low maintenance, safe in operation and low manufacturable.
Die Bildung der Wirbel ist besonders gut, wenn die wenigstens zwei Sekundärluftdüsen in etwa gleichauf entlang der Strömungsrichtung liegend angeordnet sind. Eine Ausbildung der Erfindung sieht daher vor, dass zwei benachbarte Sekundärluftdüsen einen maximalen Abstand in Strömungsrichtung zueinander haben, der das Zweifache der Länge der kurzen Seite des Strömungskanalquerschnitts beträgt. Auf diese Weise ist verhinderbar, dass sich einer der Strömungswirbel über den gesamten Strömungsquerschnitt des Strömungskanals ausbreitet, denn seine Ausdehnung wird durch einen benachbarten Strömungswirbel blockiert (begrenzt). Die Strömungswirbel sind auch mit einer gleichen Intensität ausbildbar, sodass keiner der Strömungswirbel die benachbarten dominiert oder überlagert. Somit sind weitestgehend homogene, sowie gleichmäßig ausgebildete benachbarte Strömungswirbel realisierbar.The formation of the vortices is particularly good when the at least two secondary air nozzles are located approximately equidistant along the flow direction. An embodiment of the invention therefore provides that two adjacent secondary air nozzles have a maximum distance in the flow direction to each other, which is twice the length of the short side of the flow channel cross-section. In this way it can be prevented that one of the flow vortices spreads over the entire flow cross-section of the flow channel, because its expansion is blocked (limited) by an adjacent flow vortex. The flow vortices can also be formed with an equal intensity so that none of the vortices dominates or overlaps the adjacent vortices. Thus, as far as possible homogeneous, as well as uniformly formed adjacent flow vortexes can be realized.
Besonders zu bevorzugen ist es, wenn die Sekundärluftdüsen tatsächlich gleichauf entlang der Strömungsrichtung liegend angeordnet sind. Mit anderen Worten sollten die Sekundärluftdüsen auf derselben Höhe entlang der Strömungsrichtung angeordnet sein, sodass diese durch eine einzige Ebene senkrecht zur Strömungsrichtung schneidbar sind. Auf diese Weise kann sich keiner der Wirbel über den gesamten Strömungsquerschnitt des Strömungskanals ausbreiten, denn seine Ausdehnung wird stets, d.h. schon ab dem Zeitpunkt der Eindüsung der Sekundärluft, durch einen benachbarten Strömungswirbel blockiert.It is particularly preferable if the secondary air nozzles are actually arranged lying in the same direction along the direction of flow. In other words, the secondary air nozzles should be arranged at the same height along the flow direction, so that they can be cut by a single plane perpendicular to the flow direction. In this way, none of the vortices can propagate over the entire flow cross-section of the flow channel, because its expansion is always, i. already from the time of injection of the secondary air, blocked by an adjacent flow vortex.
Besonders günstig ist eine Variante der Erfindung, bei der die Eindüsungsrichtungen wenigstens annähernd senkrecht zur Strömungsrichtung ausgerichtet sind. Bis zu 30 Grad Abweichung von der Senkrechten führen zu einer guten Ausbildung der Strömungswirbel. Je senkrechter die Eindüsungsrichtung ausgerichtet ist, desto höhere Rotationsgeschwindigkeiten der Strömungswirbel sind erzielbar. Außerdem kommt es zu einer Scherung zwischen dem Verbrennungsgasstrom und dem Sekundärluftstrom, welche die Durchmischung erheblich verbessert.Particularly favorable is a variant of the invention, in which the injection directions are aligned at least approximately perpendicular to the flow direction. Up to 30 degrees deviation from the vertical lead to a good formation of the flow vortex. The more perpendicular the injection direction is aligned, the higher rotational speeds of the flow vortex can be achieved. In addition, there is a shear between the combustion gas flow and the secondary air flow, which greatly improves the mixing.
Um eine möglichst gute Durchmischung des Verbrennungsgasstroms und der Sekundärluft zu erzielen, ist eine Ausgestaltung der Erfindung von besonderem Vorteil, bei welcher der Strömungskanal einen sich in der Strömungsrichtung an den Eindüsungsabschnitt anschließenden Mischabschnitt aufweist. In diesem Mischabschnitt sollen sich die Wirbel parallel und benachbart zueinander fortsetzen können. Deshalb sollte der Mischabschnitt keine oder nur geringe Richtungs- und/oder Querschnittsänderungen aufweisen. Die Länge des Mischabschnitts sollte auf die Strömungsgeschwindigkeiten der Sekundärluft und des Verbrennungsgasstroms ausgelegt sein, denn hiervon hängt entscheidend ab, wie weit sich die Strömungswirbel fortsetzen können. Reibung, Nebenwirbel und Ähnliches schwächen die Strömungswirbel nämlich mit zunehmender Entfernung vom Eindüsungsabschnitt ab. Der Mischabschnitt sollte dabei wenigstens dreimal so lang sein wie die Länge der kurzen Seite des Strömungskanals. Mithin sorgt der Mischabschnitt dafür, dass die Strömungswirbel zu einer maximalen Durchmischung des Verbrennungsgasstroms mit Sekundärluft führen. Entsprechend gering sind die Emissionen.In order to achieve the best possible mixing of the combustion gas flow and the secondary air, an embodiment of the invention is of particular advantage, in which the flow channel extends in the direction of flow to the injection section having subsequent mixing section. In this mixing section, the vertebrae should be able to continue parallel and adjacent to each other. Therefore, the mixing section should have no or only slight directional and / or cross-sectional changes. The length of the mixing section should be adapted to the flow rates of the secondary air and the combustion gas flow, because of this depends decisively on how far the flow vortex can continue. Friction, secondary vortices and the like weaken the flow vortices with increasing distance from the injection section. The mixing section should be at least three times as long as the length of the short side of the flow channel. Thus, the mixing section ensures that the flow vortices lead to a maximum mixing of the combustion gas flow with secondary air. The emissions are correspondingly low.
Die Vermischung des Verbrennungsgasstroms mit Sekundärluft wird in einer Version der Erfindung weiter dadurch verbessert, dass die kurze Seite von zwei gegenüberliegenden kurzen Kanalwänden ausgebildet ist, wobei wenigstens eine der kurzen Kanalwände nach außen gewölbt ist. Die Ausbildung einer gewölbten kurzen Außenwand erlaubt, dass ein rund ausgebildeter Strömungswirbel entlang der gesamten kurzen Wand rotieren kann. Es kommt nicht zu einer linearen Strömung in einer Ecke zwischen der kurzen Kanalwand und einer langen Kanalwand, in welche der Strömungswirbel nicht hineinreichen könnte. Somit kann sich hier auch kein undurchmischtes Verbrennungsgas durch den Strömungskanal bewegen. Idealerweise ist die wenigstens eine kurze Kanalwand dafür halbkreisförmig nach außen gewölbt.The mixing of the combustion gas flow with secondary air is further improved in one version of the invention in that the short side of two opposite short channel walls is formed, wherein at least one of the short channel walls is curved outwards. The formation of a domed short outer wall allows a circular flow vortex to rotate along the entire short wall. There is no linear flow in a corner between the short channel wall and a long channel wall into which the flow vortex could not reach. Thus, no unburned combustion gas can move through the flow channel here. Ideally, the at least one short channel wall is curved in a semicircular outward direction.
Zur gleichmäßigen Verteilung der Wirbel ist es von besonderem Vorteil, wenn die lange Seite eine Länge (a) und die kurze Seite eine Länge (b) aufweisen, wobei die Länge (a) der langen Seite ungefähr der Länge (b) der kurzen Seite multipliziert mit der Anzahl der Sekundärluftdüsen abzüglich einer entspricht. Dies bedeutet:
Die gewählten Verhältnisse der Längen und der Anzahl der Sekundärluftdüsen führen dazu, dass genau ein Strömungswirbel weniger innerhalb des Strömungskanals ausgebildet wird, als Sekundärluftdüsen vorhanden sind. Dabei können sich die Strömungswirbel kreisrund im Strömungskanal fortsetzen und der Durchmesser von diesen entspricht der Länge der kurzen Seite. Somit erfolgt eine bestmögliche Durchmischung über den gesamten Querschnitt des Strömungskanals. Außerdem kann jeder Wirbel in zwei Richtungen durch Sekundärluft in Rotation versetzt werden. Hierfür sollten die Sekundärluftdüsen gleichmäßig um einen konstanten Versatzabstand versetzt über die lange Seite verteilt sein. D.h. zum Beispiel, dass zwei an einer der Kanalwände angeordnete Sekundärluftdüsen einen quer zur Strömungsrichtung ausgerichteten Abstand von einander haben, welcher dem Zweifachen des Versatzabstandes entspricht. Jeweils mittig zwischen den Sekundärluftdüsen an einer der langen Kanalwände sitzt dann gegenüberliegend an der anderen Kanalwand eine weitere Sekundärluftdüse.The chosen ratios of the lengths and the number of secondary air nozzles cause just one flow vortex less within the flow channel is formed as secondary air nozzles are present. In this case, the flow vortices can continue circular in the flow channel and the diameter of these corresponds to the length of the short side. Thus, the best possible mixing takes place over the entire cross section of the flow channel. In addition, each vortex can be rotated in two directions by secondary air in rotation. For this, the secondary air nozzles should be evenly distributed over the long side offset by a constant offset distance. That is to say, for example, that two secondary air nozzles arranged on one of the channel walls have a transversely to the flow direction spaced from each other, which corresponds to twice the offset distance. In each case centrally located between the secondary air nozzles on one of the long channel walls then opposite to the other channel wall another secondary air nozzle.
Dass die Länge (a) der langen Seite nur ungefähr der Länge (b) der kurzen Seite multipliziert mit der Anzahl der Sekundärluftdüsen abzüglich einer entsprechen sollte, liegt darin begründet, dass sich die Wirbel auch problemlos leicht elliptisch ausbilden lassen. Deshalb kann die Länge (a) auch ohne große Nachteile zu erleiden, um bis zur Hälfte der Länge (b) der kurzen Seite vom Sollwert abweichen. Eine zu starke elliptische Ausbildung führt zu mehr Scherung im Gasstrom, was ebenfalls zu positiven Mischeffekten führen kann, letztlich jedoch ein unerwünscht schnelleres Abklingen der Rotation verursacht.The reason being that the length (a) of the long side should only be approximately equal to the length (b) of the short side multiplied by the number of secondary air nozzles minus one, because the vortexes can easily be easily elliptically formed. Therefore, the length (a) can also deviate from the target value by up to half the length (b) of the short side, without suffering great disadvantages. Too much elliptical formation will result in more shear in the gas stream, which may also result in positive mixing effects, but ultimately will cause an undesirably faster decay of the rotation.
Die Erfindung entfaltet ihr volles Potential der Durchmischung des Verbrennungsgasstroms mit der Sekundärluft, wenn wenigstens vier Sekundärluftdüsen, bevorzugt jedoch wenigstens sechs Sekundärluftdüsen in den Strömungskanal münden. Zwei oder drei Sekundärluftdüsen sind zwar preiswerter herstellbar, die Mehrkosten pro Sekundärluftdüse halten sich jedoch im Rahmen. Unabhängig von der Anzahl der Sekundärluftdüsen können diese von einem einzigen Strömungserzeuger mit Sekundärluft gespeist werden. Die verbesserte Durchmischung beruht bei einer höheren Anzahl an Sekundärluftdüsen insbesondere auf dem Verhältnis von zentralen Strömungswirbeln zu Strömungswirbeln, welche an die kurzen Kanalwände angrenzen. Die zentralen Strömungswirbel kollidieren auf zwei Seiten mit benachbarten Wirbeln, wodurch die Durchmischung intensiviert wird.The invention develops its full potential of mixing the combustion gas stream with the secondary air when at least four secondary air nozzles, but preferably at least six secondary air nozzles open into the flow channel. Although two or three secondary air nozzles can be produced more cheaply, the additional costs per secondary air nozzle remain within the limits. Regardless of the number of secondary air nozzles, these can be fed by a single flow generator with secondary air. The improved mixing is based on a higher number of secondary air nozzles, in particular on the ratio of central flow vortex to flow vortex, which adjoin the short channel walls. The central flow vortices collide on two sides with adjacent vortices, which intensifies mixing.
Ferner ist eine Ausbildung der Erfindung von besonderem Vorteil, bei welcher der Strömungskanal in eine Brennkammer mündet, wobei die Brennkammer bevorzugt eine Zyklonbrennkammer ist. Mit zunehmendem Abstand von den Sekundärluftdüsen nimmt die Rotationsgeschwindigkeit der Strömungswirbel ab, bis kaum noch eine Durchmischung des Verbrennungsgases mit Sekundärluft erzielt wird. Durch eine Einleitung in eine Brennkammer kann eine Änderung der Strömungsrichtung herbeigeführt werden und die Durchmischung des Verbrennungsgasstroms mit der verbliebenen Sekundärluft, sowie die Sekundärverbrennung werden weiter fortgesetzt. Sehr vorteilhaft ist dabei, dass die verbliebene Sekundärluft schon gut innerhalb des Verbrennungsgasstroms verteilt ist, bevor letzteres überhaupt in die Brennkammer mündet. Dementsprechend kann die Brennkammer relativ klein ausgebildet sein, da die Nachverbrennung schneller abläuft. Als besonders vorteilhaft erweist sich der Einsatz einer Zyklonbrennkammer, bei welcher der eingeleitete Gasstrom durch Rotation um eine Achse und damit verbundenen Reibungen, Scherungen und ähnliches nochmals gut durchmengt und nachverbrannt werden kann.Furthermore, an embodiment of the invention is of particular advantage, in which the flow channel opens into a combustion chamber, wherein the combustion chamber is preferably a cyclone combustion chamber. As the distance from the secondary air nozzles increases, the rotational speed of the flow vortices decreases, until hardly any mixing of the combustion gas with secondary air is achieved. By an introduction into a combustion chamber, a change in the flow direction can be brought about and the Mixing of the combustion gas stream with the remaining secondary air, as well as the secondary combustion will be continued. It is very advantageous that the remaining secondary air is already well distributed within the combustion gas stream, before the latter ever flows into the combustion chamber. Accordingly, the combustion chamber can be made relatively small, since the afterburning proceeds faster. Particularly advantageous is the use of a cyclone combustion chamber, in which the introduced gas flow through rotation about an axis and associated friction, shear and the like can again be thoroughly mixed and post-combusted.
Schließlich erfolgt die Anordnung des Strömungskanals zur Zyklonbrennkammer vorzugsweise exzentrisch, ggf. auch tangential, und nicht parallel zur Rotationsachse der Zyklonbrennkammer. Dabei sollte die Zyklonbrennkammer selbst rotationssymmetrisch um die Rotationsachse ausgebildet sein.Finally, the arrangement of the flow channel to the cyclone combustion chamber is preferably eccentric, possibly also tangential, and not parallel to the axis of rotation of the cyclone combustion chamber. The cyclone combustion chamber itself should be rotationally symmetrical about the axis of rotation.
Die Erfindung betrifft weiterhin ein Verfahren zum Betrieb einer Sekundärbrennkammer mit einem Strömungskanal zur Nachverbrennung eines Verbrennungsgasstroms mittels Durchmischung mit Sekundärluft, wobei der Strömungskanal eine Strömungsrichtung für den Verbrennungsgasstrom vorgibt, wobei der Strömungskanal einen Querschnitt mit einer langen Seite und einer kurzen Seite hat, wobei wenigstens zwei Sekundärluftdüsen zur Eindüsung der Sekundärluft in den Strömungskanal münden, welche innerhalb eines Eindüsungsabschnitts des Strömungskanals angeordnet sind und nicht parallel zur Strömungsrichtung ausgerichtete Eindüsungsrichtungen aufweisen, und wobei das Verfahren folgende Schritte umfasst:
- Einleiten von Verbrennungsgas in den Strömungskanal mit einer Strömungsgeschwindigkeit in Strömungsrichtung,
- Einleiten von Sekundärluft durch die Sekundärluftdüsen in den Strömungskanal mit einer Eindüsungsgeschwindigkeit,
- Ausbilden von wenigstens zwei parallelen Strömungswirbeln im Strömungskanal.
- Introducing combustion gas into the flow channel at a flow velocity in the flow direction,
- Introducing secondary air through the secondary air nozzles into the flow channel at a rate of injection;
- Forming at least two parallel flow vortices in the flow channel.
Diese Strömungswirbel setzen sich im Wesentlichen parallel im Strömungskanal fort. In der Grenzzone zwischen zwei Wirbeln können sich weitere jedoch kleinere Nebenwirbel ausbilden. Einer der Haupteinflussparameter einer sauberen Verbrennung - nämlich die Durchmischung des Verbrennungsgases mit der Sekundärluft - kann erfindungsgemäß erheblich verbessert werden. Entsprechend steigt die Gasphasenoxidation und die Emission von Kohlenwasserstoff, Kohlenmonoxid und unverbrannten Partikeln sinkt. Mithin kann so zum Beispiel eine saubere Verbrennung von Biomasse erfolgen.These flow vortices continue essentially parallel in the flow channel. In the border zone between two vertebrae, however, smaller but smaller vertebrae can form. One of the main parameters of a clean combustion - namely, the mixing of the combustion gas with the secondary air - can be significantly improved according to the invention. Accordingly, the gas phase oxidation increases and the emission of hydrocarbon, carbon monoxide and unburned particles decreases. Thus, for example, a clean combustion of biomass can be done.
Zudem ist die Sekundärbrennkammer durch die verbesserte und sehr schnelle Durchmischung insgesamt kleiner ausbildbar. Dies verringert unter anderem den benötigten Bauraum und Materialkosten. Besonders vorteilhaft ist dabei zudem, dass durch eine kleinere Speichermasse in der Sekundärbrennkammer eine wesentlich schnellere Anfahrphase realisierbar ist. Die Verbrennungsgase erreichen so besonders schnell eine Temperatur in der Sekundärbrennkammer, bei der eine Nachverbrennung möglich ist. Die optimale Temperatur liegt hierbei oberhalb von 700 °C. Emissionen in der Anfahrphase werden somit vermieden.In addition, the secondary combustion chamber can be made smaller overall due to the improved and very rapid mixing. Among other things, this reduces the required installation space and material costs. It is also particularly advantageous that a much faster start-up phase can be realized by a smaller storage mass in the secondary combustion chamber. The combustion gases thus reach a temperature in the secondary combustion chamber, in which afterburning is possible, particularly fast. The optimum temperature is above 700 ° C. Emissions during the start-up phase are thus avoided.
Die erfindungsgemäße Einleitung der Sekundärluft erfordert höchstens eine geringe Energiemenge, z.B. durch einen Strömungserzeuger wie ein Gebläse. Die Sekundärluftdüsen können dabei einfach aufgebaut sein, sodass das Verfahren mit einer wartungsarmen Sekundärbrennkammer durchführbar ist, welche zudem sicher im Betrieb und günstig fertigbar ist.The introduction of the secondary air according to the invention requires at most a small amount of energy, e.g. through a flow generator such as a fan. The secondary air nozzles can be simple in construction, so that the method with a low-maintenance secondary combustion chamber is feasible, which is also safe in operation and low manufacturable.
Eine wichtige Verfahrensalternative der Erfindung sieht dabei vor, dass die Eindüsungsgeschwindigkeit der Sekundärluft wenigstens halb so groß und höchstens viermal so groß ist wie die Strömungsgeschwindigkeit des Verbrennungsgases. Hierdurch können stabile Strömungswirbel ausgebildet werden, welche zu einer guten Durchmischung des Verbrennungsgases mit Sekundärluft führen.An important alternative method of the invention provides that the injection speed of the secondary air is at least half as large and at most four times as large as the flow velocity of the combustion gas. As a result, stable flow vortices can be formed, which lead to a good mixing of the combustion gas with secondary air.
Die Zeichnungen stellen Ausführungsbeispiele der Erfindung dar und zeigen in
-
Fig. 1 einen Querschnitt durch einen Strömungskanal mit vier Sekundärluftdüsen; -
Fig. 2 einen Querschnitt durch einen Strömungskanal mit sechs Sekundärluftdüsen; und -
Fig. 3 eine schematische Ansicht einer Sekundärbrennkammer.
-
Fig. 1 a cross section through a flow channel with four secondary air nozzles; -
Fig. 2 a cross section through a flow channel with six secondary air nozzles; and -
Fig. 3 a schematic view of a secondary combustion chamber.
Wie man erkennt, münden vier Sekundärluftdüsen 11, 12, 13, 14 zur Eindüsung der Sekundärluft L in den Strömungskanal 1. Diese sind alle innerhalb eines Eindüsungsabschnitts 2 des Strömungskanals 1 angeordnet. Insbesondere sind die Sekundärluftdüsen 11, 12, 13, 14 alle von der Ebene E-E geschnitten und liegen somit alle gleichauf entlang des Strömungskanals 1. Weiterhin weisen sie nicht parallel zur Strömungsrichtung R ausgerichtete Eindüsungsrichtungen R1, R2, R3, R4 auf. Vielmehr sind die Eindüsungsrichtungen R1, R2, R3, R4 senkrecht zur Strömungsrichtung des Verbrennungsgases G ausgerichtet.As can be seen, four
Der Strömungskanal 1 hat einen Querschnitt mit einer langen Seite 5 und einer kurzen Seite 6. Die kurze Seite 6 ist von zwei gegenüberliegenden kurzen Kanalwänden 61, 62 ausgebildet, welche beide nach außen gewölbt sind. Insbesondere sind diese halbkreisförmig nach außen gewölbt.The
Ferner haben die lange Seite 5 eine Länge a und die kurze Seite 6 eine Länge b, wobei die Länge a der langen Seite 5 ungefähr der Länge b der kurzen Seite 6 multipliziert mit der Anzahl der Sekundärluftdüsen 11, 12, 13, 14 abzüglich einer entspricht. Das heißt in der gezeigten Ausführung, dass die lange Seite 5 eine Länge a hat, welche in etwa dreimal so lang ist wie die Länge b der kurzen Seite 6.Furthermore, the
Die lange Seite 5 wird von zwei gegenüberliegenden langen Kanalwänden 51, 52 ausgebildet, wobei zwei Sekundärluftdüsen 12, 14 an der ersten langen Kanalwand 51 und zwei Sekundärluftdüsen 11, 13 an der zweiten langen Kanalwand 52 angeordnet sind. Hierbei sind die an der ersten langen Kanalwand 51 angeordneten Sekundärluftdüsen 12, 14 jeweils versetzt um einen quer zur Strömungsrichtung des Verbrennungsgases G ausgerichteten Versatzabstand c zu den an der zweiten langen Kanalwand 52 angeordneten Sekundärluftdüsen 11, 13 angeordnet. Der Abstand e zwischen zwei auf einer Seite angeordneten Sekundärluftdüsen 11, 13 oder 12, 14 beträgt entsprechend dem Zweifachen des Versatzabstandes c. Schließlich sind die am nächsten zu den kurzen Kanalwänden 61, 62 angeordneten Sekundärluftdüsen 11, 14 nicht ganz außen angeordnet, sondern diese haben einen Abstand d zum am weitesten außen liegenden Punktes der kurzen Kanalwände 61, 62.The
Gleichzeitig zum Verbrennungsgas G, welches mit der Strömungsgeschwindigkeit vG durch den Strömungskanal 1 strömt, kann nunmehr Sekundärluft L mit einer Eindüsungsgeschwindigkeit vL durch die Sekundärluftdüsen 11, 12, 13, 14 in den Strömungskanal 1 eingeleitet werden. Durch die gegenüberliegend angeordneten Sekundärluftdüsen 11, 12, 13, 14 und die Versatzabstände c entstehen 3 parallele Strömungswirbel W, wobei benachbart angeordnete Strömungswirbel W jeweils eine gegenläufige Rotationsrichtung haben. Die Rotationsgeschwindigkeiten der Strömungswirbel W werden so kaum abgebremst und können sich sehr weit parallel zueinander fortsetzen, insbesondere in einem nicht dargestellten Mischabschnitt.Simultaneously with the combustion gas G, which flows through the
Um gute stabile Strömungswirbel W und ein gutes Verhältnis der Anteile von Verbrennungsgas G und Sekundärluft L zu erreichen, sollte die Eindüsungsgeschwindigkeit vL der Sekundärluft L wenigstens halb so groß und höchstens viermal so groß sein wie die Strömungsgeschwindigkeit vG des Verbrennungsgases G. Zusätzlich können hierfür die Querschnittsflächen des Strömungskanals 1 und die kumulierte Querschnittsfläche der Sekundärluftdüsen 11, 12, 13, 14 aufeinander abgestimmt sein. Durch die Durchmischung des Verbrennungsgases G mit Sekundärluft L wird das Verbrennungsgas G im Strömungskanal 1 nachverbrannt.In order to achieve good stable flow vortices W and a good ratio of the proportions of combustion gas G and secondary air L, the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G. In addition, this can the cross-sectional areas of the
Wie man erkennt, münden sechs Sekundärluftdüsen 11, 12, 13, 14, 15, 16 zur Eindüsung der Sekundärluft L in den Strömungskanal 1. Diese sind alle innerhalb eines Eindüsungsabschnitts 2 des Strömungskanals 1 angeordnet. Insbesondere sind die Sekundärluftdüsen 11, 12, 13, 14, 15, 16 alle von der Ebene E-E geschnitten und liegen somit alle gleichauf entlang des Strömungskanals 1. Weiterhin weisen sie nicht parallel zur Strömungsrichtung R ausgerichtete Eindüsungsrichtungen R1, R2, R3, R4, R5, R6 auf. Vielmehr sind die Eindüsungsrichtungen R1, R2, R3, R4, R5, R6 senkrecht zur Strömungsrichtung des Verbrennungsgases G ausgerichtet.As can be seen, six
Der Strömungskanal 1 hat einen Querschnitt mit einer langen Seite 5 und einer kurzen Seite 6. Die kurze Seite 6 ist von zwei gegenüberliegenden kurzen Kanalwänden 61, 62 ausgebildet, welche beide nach außen gewölbt sind. Insbesondere sind diese halbkreisförmig nach außen gewölbt.The
Die lange Seite 5 wird von zwei gegenüberliegenden langen Kanalwänden 51, 52 ausgebildet, wobei zwei Sekundärluftdüse 13, 15 an der ersten langen Kanalwand 51 und zwei Sekundärluftdüse 12, 14 an der zweiten langen Kanalwand 52 angeordnet sind. Die verbleibenden zwei Sekundärluftdüsen 11, 16 sind jeweils an einer der kurzen Kanalwände 61, 62 angeordnet. Hier mündet Sekundärluftdüse 16 tangential in die halbkreisförmige Wölbung von der zweiten kurzen Kanalwand 62. Schließlich ist Sekundärluftdüse 16 auch ganz außen angeordnet, sodass kein Abstand zum am weitesten außen liegenden Punkt der zweiten kurzen Kanalwand 62 vorliegt. Sekundärluftdüse 11 mündet exzentrisch, jedoch nicht tangential in die halbkreisförmige Wölbung der ersten kurzen Kanalwand 61 und ist dabei nicht senkrecht zu den langen Kanalwänden 51, 52 ausgerichtet.The
Die an der ersten langen Kanalwand 51 angeordneten Sekundärluftdüsen 12, 14 und die an der zweiten kurzen Kanalwand 62 angeordnete Sekundärluftdüse 16 sind jeweils versetzt um einen quer zur Strömungsrichtung des Verbrennungsgases G ausgerichteten Versatzabstand zu den an der zweiten langen Kanalwand 52 angeordneten Sekundärluftdüsen 13, 15 sowie der an der ersten kurzen Kanalwand 61 angeordneten Sekundärluftdüse 11 angeordnet.The arranged on the first
Gleichzeitig zum Verbrennungsgas G, welches mit der Strömungsgeschwindigkeit vG durch den Strömungskanal 1 strömt, kann nunmehr Sekundärluft L mit einer Eindüsungsgeschwindigkeit vL durch die Sekundärluftdüsen 11, 12, 13, 14, 15, 16 in den Strömungskanal 1 eingeleitet werden. Durch die gegenüberliegend angeordneten Sekundärluftdüsen 11, 12, 13, 14, 15, 16 und die Versatzabstände entstehen fünf benachbart angeordnete Strömungswirbel W mit jeweils gegenläufigen Rotationsrichtungen. Die Rotationsgeschwindigkeiten der Strömungswirbel W werden so kaum abgebremst und können sich sehr weit parallel zueinander fortsetzen, insbesondere in einem nicht dargestellten Mischabschnitt.Simultaneously with the combustion gas G, which flows through the
Um gute stabile Strömungswirbel W und ein gutes Verhältnis der Anteile von Verbrennungsgas G und Sekundärluft L zu erreichen, sollte die Eindüsungsgeschwindigkeit vL der Sekundärluft L wenigstens halb so groß und höchstens viermal so groß sein wie die Strömungsgeschwindigkeit vG des Verbrennungsgases G. Durch die Durchmischung des Verbrennungsgases G mit Sekundärluft L wird das Verbrennungsgas G im Strömungskanal 1 nachverbrannt.In order to achieve good stable flow vortices W and a good ratio of the proportions of combustion gas G and secondary air L, the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G. By the mixing of the combustion gas G with secondary air L, the combustion gas G is post-combusted in the
Weiterhin weist der Strömungskanal 1 einen sich in der Strömungsrichtung R an den Eindüsungsabschnitt 2 anschließenden Mischabschnitt M auf. Mit diesem mündet der Strömungskanal 1 schließlich in eine als Zyklonbrennkammer ausgebildete Brennkammer 102. Insbesondere mündet der Strömungskanal 1 quer zur Rotationsachse der Zyklonbrennkammer in diese. Ob tangential und/oder exzentrisch ist in der Abbildung nicht erkennbar.Furthermore, the
Ein in einer Primärkammer 101 erzeugtes Verbrennungsgas G kann nunmehr mit einer in Strömungsrichtung R ausgerichteten Strömungsgeschwindigkeit vG durch eine Eintrittsöffnung 3 in den Strömungskanal 1 eingeleitet werden. Gleichzeitig ist Sekundärluft L mit einer Eindüsungsgeschwindigkeit vL durch die Sekundärluftdüsen 11, 12 in den Strömungskanal 1 einleitbar. Hierdurch bilden sich parallele Strömungswirbel im Strömungskanal 1 aus und setzen sich im Mischabschnitt M parallel fort. Mit zunehmendem Fortschritt in Strömungsrichtung R nimmt dabei die Rotationsgeschwindigkeit der Strömungswirbel ab. Anschließend verlässt das Verbrennungsgas G gut durchmischt mit Sekundärluft L den Strömungskanal 1 durch eine Austrittsöffnung 4 und strömt in die Brennkammer 102 ein. Sowohl im Strömungskanal 1 als auch in der Brennkammer 102 kann das Verbrennungsgas G dabei nachverbrannt werden. Dies ist insbesondere abhängig von der Temperatur des Verbrennungsgases G, die nach einem Brennerstart aufgrund der geringen Volumina der Sekundärbrennkammer 100 schnell ansteigt. Überschreitet das Verbrennungsgas G eine bestimmte Temperatur, entzündet es sich selbstständig bei der Anreicherung mit Sekundärluft L.A combustion gas G produced in a
Um gute stabile Strömungswirbel und ein gutes Verhältnis der Anteile von Verbrennungsgas G und Sekundärluft L zu erreichen, sollte die Eindüsungsgeschwindigkeit vL der Sekundärluft L wenigstens halb so groß und höchstens viermal so groß sein wie die Strömungsgeschwindigkeit vG des Verbrennungsgases G.In order to achieve good stable flow vortices and a good ratio of the proportions of combustion gas G and secondary air L, the injection speed v L of the secondary air L should be at least half and at most four times as large as the flow velocity v G of the combustion gas G.
Claims (10)
- Secondary combustion chamber (100) having a flow duct (1) for the recombustion of a combustion gas stream (G) by mixing with secondary air (L), wherein the flow duct (1) predefines a flow direction (R) for the combustion gas stream (G),
wherein the flow duct (1) has a cross section with a long side (5) and with a short side (6), wherein at least two secondary air nozzles (11, 12, 13, 14, 15, 16) for injection of the secondary air (L) issue into the flow duct (1), which secondary air nozzles are arranged within an injection section (2) of the flow duct (1) and have injection directions (R1, R2, R3, R4, R5, R6) oriented non-parallel with respect to the flow direction (R), wherein
the long side (5) is formed by two opposite long duct walls (51, 52), characterized in that at least two secondary air nozzles (11, 12, 13, 14, 15, 16) are arranged on the first long duct wall (51) and at least two secondary air nozzles (11, 12, 13, 14, 15, 16) are arranged on the second long duct wall (52), and wherein the secondary air nozzles (11, 12, 13, 14, 15, 16) arranged on the first long duct wall (51) are arranged in each case so as to be offset, by an offset distance (c) oriented perpendicular to the flow direction (R), with respect to the secondary air nozzles (11, 12, 13, 14, 15, 16) arranged on the second long duct wall (52). - Secondary combustion chamber (100) according to Claim 1,
characterized in that two adjacent secondary air nozzles (11, 12, 13, 14, 15, 16) have a maximum distance to one another, as viewed in the flow direction (R), of two times the length of the short side (6). - Secondary combustion chamber (100) according to either of Claims 1 and 2,
characterized in that the injection directions (R1, R2, R3, R4, R5, R6) are oriented at least approximately perpendicular to the flow direction (R). - Secondary combustion chamber (100) according to one of the preceding claims,
characterized in that the flow duct (1) has a mixing section (M) which adjoins the injection section (2) as viewed in the flow direction (R). - Secondary combustion chamber (100) according to one of the preceding claims,
characterized in that the short side (6) is formed by two opposite short duct walls (61, 62), wherein at least one of the short duct walls (61, 62) is bulged outward. - Secondary combustion chamber (100) according to one of the preceding claims,
characterized in that the long side (5) has a length (a) and the short side (6) has a length (b), wherein the length (a) of the long side (5) corresponds approximately to the length (b) of the short side (6) multiplied by the number of secondary air nozzles (11, 12, 13, 14, 15, 16) minus one. - Secondary combustion chamber (100) according to one of the preceding claims,
characterized in that at least four secondary air nozzles (11, 12, 13, 14, 15, 16) issue into the flow duct (1). - Secondary combustion chamber (100) according to one of the preceding claims,
characterized in that the flow duct (1) issues into a cyclone combustion chamber (102). - Method for operating a secondary combustion chamber (100) according to one of Claims 1 to 8, characterized by the following steps:a) introducing combustion gas (G) into the flow duct (1) with a flow speed (vG) in the flow direction (R),b) introducing secondary air (L) into the flow duct (1) with an injection speed (vL) through the secondary air nozzles (11, 12, 13, 14, 15, 16),c) generating at least two parallel flow vortices (W) in the flow duct (1).
- Method according to Claim 9,
characterized in that the injection speed (vL) of the secondary air (L) is at least half, and at most four times, the flow speed (vG) of the combustion gas (G).
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DE102011116723A DE102011116723A1 (en) | 2011-10-24 | 2011-10-24 | Secondary combustion chamber with secondary air injection |
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CN108317520B (en) * | 2017-12-21 | 2019-08-23 | 北方重工集团有限公司 | A kind of garbage incinerator double-layer vortex secondary air system |
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