Technical field
[0001] The invention relates to combustion of low calorific fuels from alternative sources
and also from standardised sources.
State of the art
[0002] Burners for combustion of low calorific fuels has to be designed to be able to cope
with variable parameters of fuel. Composition of fuel varies according to the process
from which it comes and how it was obtained. In fuel various incombustible components
can occur, most often these are carbon dioxide especially by biofuels or nitrogen,
which gets into fuel generally during fuelification of solids by the air. Except the
instable concentration of inert substances also the composition of combustible components
can fluctuate, mostly methane, hydrogen, carbon monoxide. The properties of methane,
hydrogen, and carbon monoxide are significantly different. They have different weight,
calorific value, and also combustion velocity.
[0003] The combustion velocity is absolutely crucial and has to be considered by designing
of the burner. Simultaneously, the construction has to be designed so, that it is
possible to satisfy various operating conditions. For ignition of the burner natural
fuel is often used, which has significantly higher calorific value than low calorific
fuels. One of the requirements of the operator used to be also the possibility of
power regulation within certain range. Therefore, the designer has to take into consideration
the fuel flow rate and air velocity and suggest a solution to avoid disruption of
flame and its flashback. It is difficult to keep these parameters.
[0004] There exist many solutions, which approach the matter in different ways. Usually,
the fuel is supplied by central tube, to which further technical elements are attached.
These may be various types of whirlers or parts which ensure mixing of individual
components, it means fuel and combustion air. The solutions according to prior art
utilise the in steps supply of the fuel or air and solve the distribution and mixing
of individual flows in different ways.
[0005] In the document
EP 0 487 700 B1, so called matrix burner with a burner head specially designed for combustion of
low calorific fuels, is described. In the middle of the assembly a fuel supply tube
on which the entire head is fixed, is located. The head is composed of two steel sheets
which are compressed together. The burner head is on the sheets provided with matrix
arrangement openings, where each opening acts as an individual small burner. The fuel
is then directly mixed with combustion air to form a turbulent flow.
[0006] The burner described in the document
US2016238241 (A1) is intended to combustion of lean fuel, it means low calorific fuel (for example
synthetic fuel resulting from the fuelification of biomass). The construction of the
burner utilizes two-stage air supply to achieve enlargement of the flame and a favourable
distribution of temperature field. The burner is provided with central fuel supply,
into which quality fuel through four openings can be mixed in order to increase calorific
value or for support of the stability. With the expanding burner on the output, the
combustion air is gradually blended into the flame.
[0007] In the document
WO2014204333 (A1) a burner for flaring which is intended to thermal liquidation of waste fuels (e.g.
methane with a high amount of carbon dioxide) without utilization of their energy,
is described. The supply pipe is extended twice and on the output from the flare,
a whirler is disposed, in order to set the fuel into motion and to achieve turbulent
flow. At the end, in the center a cone is inserted, which directs the fuel towards
the whirler. Behind the cone the fuel circulates toward the axis of the burner and
due to this better mixing is achieved.
[0008] The device described in
US2008299506 (A1) is a metallurgical burner primarily designed for burning of low calorific fuels.
The burner has a central pipe for air supply, around which a fuel supply pipe is arranged.
From outer direction secondary air is fed, so that all the fuel is burnt out. Into
the fuel flow a whirler creating turbulant flow is placed. It is possible to modify
the whirler according to used fuel, especially according to its calorific value.
[0009] The document
WO2007012755 (A1) describes symmetric burner. Along the central axis individual flows of substances
are gradually fed. Through the central tube fuel is supplied, from which a part is
separated, and before burning is mixed with the air in a special chamber. A perforated
whirler which has conical shape is placed at the end of the central tube, in order
to put the fuel into direction. Premixed mixture flows from the chamber through nozzles
directly to burning flame. Secondary air is fed from the outside end using whirling
element is directed to achieve its rotation and mixing,
[0010] The document
EP 1 436 546 discloses a burner which utilises the co-stream arrangement of the fuel and the air.
The feature of the burner is a conical extension ending with circular array of nozzles
which are directed to the central surface. Several types of assembly geometry with
different mixing ratios and different influence on turbulent flow are proposed. The
document
US2013036741 (A1) discloses a burner according to the preamble of claim 1.
[0011] The aim of the invention is to present a burner for low calorific fuels which would
ensure sufficient stability of the flame and which would also eliminate undesired
critical conditions arising during its operation when disruption of the flame or fire
penetration into the burner body occurrs.
Summary of the invention
[0012] The above mentioned deficiencies are eliminated by a burner according to claim 1.
[0013] In a preferred embodiment the openings on the whirler are arranged in three concentric
circular rows.
[0014] In another preferred embodiment the fuel supply pipe is provided on its wall with
a weld-on sleeve for connection of a pressure gauge or other measuring device.
[0015] In another preferred embodiment screws for aretation of an atomiser are located on
a free end of the support tube.
Brief description of drawings
[0016] The invention will be further described using drawings, where Fig.1 is a longitudinal
cross-section of a burner according to the invention with arrangement of individual
parts, Fig 2 represents side view of the burner according to the invention in the
direction of media flow, Fig. 3 represents a detail of the burner head in a perspective
view and Fig. 4 represents a detail of the whirler of combustion air according to
the invention in a perspective view.
Preferred embodiments of the invention
[0017] In Fig.1 a longitudinal section of a burner can be seen, which consists of a fuel
supply pipe 8 provided with connecting flange 10, through which the fuel F enters
in the direction of the arrow. Further is the fuel supply pipe 8 attached to a central
burner tube 5 which has a front face 6 on the side of the supply pipe 8, which has
an opening in the middle to allow insertion of a support tube 7. The whole burner
is not displayed, only its built-in assembly. Around it there are situated other standard
parts of the burner, which are known to skilled persons. To the central burner tube
5, at its output end is, via weld-on reduction 3, with its inner perimeter 15 a whirler
2 attached. The central burner tube 5 and the weld-on reduction 3, which terminates
the central burner tube 5, form together with the support tube 7 an assembly, which
defines the flow of combustion fuel F. Thus, the fuel F flows in the direction of
the arrow into space, which has a shape of a hollow cylinder, formed by the central
burner tube 5 and the support tube 7. This cylindrical space has such a specific length,
so that the previous turbulent flow is maximally stabilised. The stabilisation contributes
to the uniform distribution of the fuel inside the cylindrical space and the fuel
is then uniformly burnt out. The support tube 7 can be used for addition of an atomiser
(not shown) for liquid fuel. At the free end of the support tube 7, screws 12 for
aretation of such atomiser are situated. At the opposite inner end of the support
tube 7 a groove on the burner output is milled into which a burner head 4 is inserted
and welded-on, through which the fuel is distributed into combustion space.
[0018] On the wall of the fuel supply pipe 8 a weld-on sleeve 11 is located for connection
of pressure gauge or other measuring device, which can be seen in Fig. 2. On the connecting
flange 10 a shutter is possible to insert in order to regulate pressure on the desired
level.
[0019] In Fig.3 the burner head 4 in perspective view is shown. The fuel F flowing through
the burner head 4 via nozzles 13, which are spaced in a circle at the inner perimeter
forming the primary stage of the burner 1, is distributed uniformly along the central
axis of the burner 1. This flow is important especially for the flame core stabilisation.
In a stable situation in the flame core the flame envelope can be provided in a high
rotational mode without disruption of the flame or unstable combustion. Burner head
4 is at its outer perimeter further provided with angled grooves 14, which change
the momentum direction of flowing fuel and form the secondary stage of the burner
1. The fuel gets after passing through the angled grooves 14 into tangential rotation
along the central axis of the burner 1. Rotational flow causes better mixing of the
fuel with the combustion air A, which arrives to the end of central burner tube 5
and simultaneously the flame is partially attached to the burner head 4.
[0020] In Fig. 4 whirler 2 in perspective view is shown, its wall 16 has conical geometry
extending outwardly from the burner, which has a positive effect on the flow. In the
illustrated embodiment, there are openings 9 spaced in three concentric circular rows
on the wall 16 of the whirler 2, through which the combustion air flows. It is evident,
that the circle with openings may be only one or there can be another number of concentric
circles. After passage through the individual openings 9 there is a change in the
air flow, namely the strong turbulent flow is created, due to which is the fuel brought
into a tangential rotation and mixed with the combustion air even better. The angle
of inclination of the wall 16 of the whirler 2 has an important role, since due to
this inclination it is possible to direct partially the airflow, to direct it towards
the centre of the flame, and causing a complete combustion.
[0021] The burner head 4 has defined number of nozzles 13 arranged in a circle, whereas
the number and size of nozzles 13 is determined based on the requirements for maximum
performance, according to which the dimensions are determined so, that the requested
amount of fuel flows through the primary stage created in this way. The number, width,
and depth of angled grooves 14 are determined as to allow the remaining fuel to flow
through these grooves at maximum power and the groove 14 inclination angle is determined
relative to the plane of the burner head 4 in such a way, to ensure optimal turbulent
flow in a tangential direction.
Industrial applicability.
[0022] The burner is intended for combustion of different types of low calorific fuels,
also from other alternative devices, such as fuelifiers. The burner is applicable
in plants, where waste fuels occurs, whose energy is let unused in burners with flaring
and flue gases are emitted without use into the atmosphere. Another area where it
is possible to use the burner, are biogas plants and heat sources connected thereto.
1. A burner (1) comprising an air supply pipe, a central burner tube (5), a fuel supply
pipe (8) attached to the central burner tube (5), which is terminated by a front face
(6) on the side of the fuel supply pipe (8), the burner (1) further comprising a support
tube (7) fixed to said front face (6), and a burner head (4) mounted to said support
tube (7) at the burner outlet, the burner head (4) being provided with nozzles (13)
arranged in a circle near to the inner perimeter of the burner head (4) and forming
the primary stage of the burner (1), the burner (1) further comprising a whirler (2)
with its inner perimeter (15) arranged onto the central burner tube (5) at its outlet
end, wherein the whirler's surface (16) has a conical shape extending outwardly and
openings (9), arranged in a circle, are provided in the whirler's surface (16), characterized in that the burner head (4) is provided with angled grooves (14) on the outer perimeter,
which form the secondary stage of the burner (1).
2. The burner according to claim 1, characterized in, that the openings (9) on the whirler (2) are arranged in three concentric circular rows.
3. The burner according to claim 1, characterized in, that the fuel supply pipe (8) is provided on its wall with a weld-on sleeve (11) for connection
of a pressure gauge or other measuring device.
4. The burner according to claim 1 characterized in, that screws (12) for aretation of an atomiser are located on a free end of the support
tube (7).
1. Brenner, bestehend aus einer Zuführungsluftrohrleitung, einer zentralen Brennerrohr
(5), aus einer Zuführungsbrennstoffrohrleitung, die an die zentrale Brennerrohr (5)
angeschlossen ist, die mit einem Blendstirn (6) auf der Seite der Zuführungsluftrohrleitung
(8) beendet ist, wobei der Brenner (1) ein Tragrohr (7) beinhaltet, die auf den erwähnten
Blendstirn (6) befestigt ist, und beinhaltet auch einen Brennerkopf (4), der auf der
erwähnten Tragrohr (7) auf dem Brennerausgang angeordnet ist, wobei der Brennerkopf
(4) mit Düsen (13) versehen ist, die in einem Kreis in der Nähe des Innenumfangs des
Brennkopfes (4) angeordnet sind, und die eine primäre Stufe des Brenners (1) bilden,
wobei der Brenner (1) weiter einen Verwirbler (2) beinhaltet, der mit seinem Innenumfang
(15) auf dem Ausgangsende der zentralen Brennerrohr (5) angeordnet ist, wobei die
Oberfläche (16) des Verwirblers (2) eine konische Form hat, die sich in Richtung aussen
verbreitet und die Oberfläche (16) ist mit Öffnungen (9) versehen, die im Kreis angeordnet
sind, dadurch gekennzeichnet, dass der Brennerkopf (4) auf dem äusseren Umfang mit geneigten Rillen (14) versehen ist,
die eine sekundäre Stufe des Brenners (1) bilden.
2. Brenner nach dem Anspruch 1, dadurch gekennzeichnet, dass die Öffnungen (9) auf dem Verwirbler (2) in drei konzentrischen Kreisreihen verteilt
sind.
3. Brenner nach dem Anspruch 1, dadurch gekennzeichnet, dass die Zuführungsluftrohrleitung (8) auf seiner Wand durch einen Aufschweissstück (11)
für Anschliessung eines Manometers oder einer anderen Messeinrichtung versehen ist.
4. Brenner nach dem Anspruch 1, dadurch gekennzeichnet, dass auf dem freien Ende der Tragrohr (7) Schrauben (12) für Aretation eines beigeschlossenen
Atomizers angeordnet sind.
1. Brûleur comprenant une conduite d'alimentation en air, un tube de brûleur central
(5), une conduite d'alimentation en combustible raccordée au tube de brûleur central
(5) qui se termine par une face d'obturation (6) du côté de la conduite d'alimentation
(8), le brûleur (1) comprenant un tube de support (7) fixé sur ladite face d'obturation
(6) et une tête de brûleur (4) disposée sur ledit tube de support (7) à la sortie
du brûleur, la tête de brûleur (4) étant munie des buses (13) disposées en cercle
à la périphérie interne de la tête de brûleur (4) et formant l'étage primaire du brûleur
(1), le brûleur (1) comprenant en outre un tourbillonneur (2) s'appuyant par sa périphérie
interne (15) à l'extrémité de sortie du tube de brûleur central (5), la surface (16)
du tourbillonneur (2) ayant une forme conique s'élargissant vers l'extérieur et la
surface (16) étant munie des orifices (9) disposés en cercle, caractérisé en ce que la tête de brûleur (4) est sur sa périphérie externe munie des rainures inclinées
(14) qui forment l'étage secondaire du brûleur (1).
2. Brûleur selon la revendication 1, caractérisé en ce que les orifices (9) du tourbillonneur (2) sont répartis en trois rangées circulaires
concentriques.
3. Brûleur selon la revendication 1, caractérisé en ce que la conduite d'alimentation (8) en combustible est munie de son côté par un manchon
(11) pour raccorder un manomètre ou un autre appareil de mesure.
4. Brûleur selon la revendication 1, caractérisé en ce que des vis (12) sont disposés à l'extrémité libre du tube de support (7) pour verrouiller
l'atomiseur ajouté.