U.S. patent application number 14/619420 was filed with the patent office on 2015-08-13 for igniter lance and method for operating a burner having said igniter lance.
The applicant listed for this patent is ALSTOM Technology Ltd. Invention is credited to Thomas HILBER, Frank Michael KLUGER, Patrick MOENCKERT, Dragisa RISTIC.
Application Number | 20150226431 14/619420 |
Document ID | / |
Family ID | 50073001 |
Filed Date | 2015-08-13 |
United States Patent
Application |
20150226431 |
Kind Code |
A1 |
RISTIC; Dragisa ; et
al. |
August 13, 2015 |
IGNITER LANCE AND METHOD FOR OPERATING A BURNER HAVING SAID IGNITER
LANCE
Abstract
The igniter lance include a lance fuel duct for pulverised fuel
and an electric igniter for ignition of the pulverized fuel passing
through the lance fuel duct.
Inventors: |
RISTIC; Dragisa;
(Wendlingen, DE) ; HILBER; Thomas;
(Kernen-Stetten, DE) ; MOENCKERT; Patrick;
(Benningen, DE) ; KLUGER; Frank Michael;
(Schwaebisch Gmuend, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALSTOM Technology Ltd |
Baden |
|
CH |
|
|
Family ID: |
50073001 |
Appl. No.: |
14/619420 |
Filed: |
February 11, 2015 |
Current U.S.
Class: |
431/6 ;
431/258 |
Current CPC
Class: |
F23Q 9/00 20130101; F23D
1/00 20130101; F23Q 3/00 20130101; F23D 2207/00 20130101; F23D
2201/10 20130101; F23D 1/04 20130101; F23Q 3/008 20130101; F23D
2201/20 20130101 |
International
Class: |
F23Q 3/00 20060101
F23Q003/00; F23D 1/00 20060101 F23D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2014 |
EP |
14154855.2 |
Claims
1. An igniter lance comprising a lance fuel duct for pulverised
fuel and an electric igniter for ignition of the pulverized fuel
passing through the lance fuel duct.
2. The igniter lance of claim 1, wherein the electric igniter is
arranged for providing a plasma in an area in front of the igniter
lance.
3. The igniter lance of claim 1, wherein the electric igniter is
housed in the lance fuel duct at a terminal part thereof.
4. The igniter lance according to claim 1, further comprising at
least one deflector for deflecting at least one part of the
pulverized fuel flowing through the lance fuel duct towards the
formed plasma.
5. The igniter lance according to claim 4, wherein the at least one
deflector comprises at least one protrusion extending from a wall
of lance fuel duct.
6. The igniter lance according to claim 5, wherein the at least one
protrusion extends over the periphery of the first wall and/or the
second wall.
7. The igniter lance according to claim 5, wherein the at least one
protrusion (8) has a sloped surface with a thinner part farther
from a mouth and a thicker part closer to the mouth, the sloped
surface defining an angle with the wall from which they extend, the
angle being between 5 and 90 degree and preferably between 10 and
45 degree.
8. The igniter lance according to claim 1, wherein the lance fuel
duct has a flared terminal part.
9. The igniter lance according to claim 8, wherein the flared
terminal part defines a cone having an opening angle of between 0
and 90 degree, preferably between 30 and 75 degree.
10. The igniter lance according to claim 4, wherein the deflector
does not extend in the flared terminal part.
11. The igniter lance according to claim 4, wherein the deflector
extends in the flared terminal part.
12. The igniter lacze according to claim 8, wherein the electric
igniter does not extend in the flared terminal part.
13. The igniter lance according to claim 8, wherein the electric
igniter extends in the flared terminal part or protrudes further
into an area facing the flared terminal part.
14. A method for operating a burner having a igniter lance, at
least one or more burner fuel duct for pulverised fuel, at least
one or more air duct, and at least an igniter lance according to
claim 1; the method comprising: providing a plasma by the electric
igniter, supplying pulverized fuel through the lance fuel duct,
igniting the pulverized fuel supplied through the lance fuel duct
through the plasma provided by the electric igniter, generating an
ignition flame, and supplying pulverized fuel through the burner
fuel duct, igniting the pulverized fuel supplied through the burner
fuel duct through the ignition flame.
15. A burner comprising at least a burner fuel duct for pulverised
fuel, at least an air duct, and at least an igniter lance according
to claim 1, wherein the burner has a igniter lance housed within a
core air duct and this is in turn housed within the burner fuel
duct, furthermore the burner fuel duct is surrounded externally by
one or more air duct, or the burner has the igniter lance housed
within the burner fuel duct, furthermore the burner fuel duct is
surrounded externally by one or more air duct, or the burner has
the igniter lance housed within one of the at least one air duct,
or the burner has the igniter lance housed within each air duct.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to European application
14154855.2 filed Feb. 12, 2014, the contents of which are hereby
incorporated in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to an igniter lance and a
method for operating a burner having said igniter lance.
BACKGROUND
[0003] Beside rectangular jet burners, round burners (i.e. burners
with concentric flows) are the most frequently used burners (e.g.
as main and/or start-up burner) in furnaces of, for example, large
power plants for burning pulverized fossil fuels and/or
biomass.
[0004] Round burners are supplied with pulverized fuel as the main
fuel (e.g. pulverized coal). The ignition of the main fuel requires
the use of oil or gas that usually is ignited by means of electric
sparks. During the start-up oil or gas are used to generate a flame
that in turn ignites the main fuel (pulverized fossil fuel and/or
biomass). After ignition of the main fuel, the oil or gas is
usually switched off.
[0005] This concept has the disadvantage that significant amounts
of expensive oil or gas are consumed before the combustion with
main fuel can stand alone without support of a flame generated by
oil or gas as secondary fuels.
[0006] Furthermore, a complex infrastructure for storage,
preparation, transport and supply of oil or gas has to be installed
and maintained in addition to the infrastructure for the pulverized
main fuel.
[0007] To overcome the necessity of operating an ancillary firing
system using oil or gas for igniting the main fuel, DE 10 2011 056
655 describes a round or rectangular shaped main burner, operating
with pulverized fuel as the main fuel (e.g. dry lignite), and
having at least one plasma lance used for direct ignition of the
main fuel.
[0008] The plasma lance is able to generate small flames, therefore
often a number of plasma lances are needed to ignite the pulverized
fuel and in addition the positioning of the plasma lance is
relevant for a correct ignition of the pulverized fuel.
SUMMARY
[0009] An aspect of the disclosure comprises providing an apparatus
and method for start-up of an industrial scale burner operating
with pulverized fuel (e.g. fossil fuels, biomass, and others)
without the prior need of oil and/or gas for ignition of the
pulverized main fuel. This apparatus is hereafter referred to as
the igniter lance.
[0010] This and further aspects are attained by providing the
igniter lance and a method for in accordance with the accompanying
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Characteristics and advantages become apparent from the
description of a preferred but non-exclusive embodiment of the
igniter lance and method for operating a burner having said lance,
illustrated by the non-limiting example in the accompanying
drawings, in which:
[0012] FIGS. 1 and 2 show examples of the terminal part of an
igniter lance;
[0013] FIG. 3 shows an example of a burner with the igniter
lance.
DETAILED DESCRIPTION
[0014] FIG. 1 shows an igniter lance 1 having a lance fuel duct 2
for pulverized fossil fuel and/or biomass fuel (e.g. coal, lignite,
dry lignite, biomass, bituminous coal, and other), and an electric
igniter 3 for the ignition of the pulverized fuel passing through
the lance fuel duct 2.
[0015] The electric igniter 3 can be of different types and can
include for example: [0016] a microwave system generating a plasma
flame, [0017] a systems implementing electrodes connected to an
electric circuit for generating one or more electric arcs, [0018] a
systems implementing electrodes connected to an electric circuit
for generating electric sparks, [0019] other systems creating
ionizing and/or electrical fields or discharges.
[0020] The electric igniter 3 is flowed around or flowed through
(allowed by suitable openings applied) by any oxidizing or inert
gas (preferably air), and provides the necessary energy to form a
plasma 4 that is sufficient to ignite the pulverised fuel supplied
through the lance fuel duct 2.
[0021] The igniter lance 1 does not need oil or gas for operation,
but it is only supplied with electric power and pulverized fuel
transported by air and/or another oxidizing medium.
[0022] Preferably, within the terminal part of the lance fuel duct
2 there is provided a deflector 5 facing a mouth 6. The purpose of
the deflector 5 is to deflect a part of the pulverized fuel passing
through the lance fuel duct 2 towards a plasma 4 formed by the
electric igniter 3 in an area 7 facing the igniter lance 1.
[0023] The deflector 5 comprises protrusions 8 extending from a
wall 9 and/or a wall 10; in the example presented in FIG. 1, the
deflector 5 comprises protrusions 8 which extend from the wall 9
and which define a teeth-ring.
[0024] The protrusions 8 in the presented example in FIG. 1 extend
over the periphery of the wall 9, preferably over the whole
circumference of the lance fuel duct 2 and are equidistant from one
another. The protrusions 8 can also not be equidistant from one
another.
[0025] The protrusions 8 have a sloped surface 11 with their
thinner part 12 farther from the mouth 6 and a thicker part 13
closer to the mouth 6. The sloped surface 11 defines an angle A
with the wall 9 from which they extend, with the angle A being
between 5 (five) and 90 (ninety) degree and with preferably between
10 (ten) and 45 (forty-five) degree. For example, in certain
embodiments approximately 90 degree could be applied in order to
reduce the velocity of the pulverised fuel in the lance fuel duct 2
and in order to increase the pulverised fuel particles' residence
time in the plasma 4.
[0026] Advantageously the deflector 5 is able to deflect up to
about 50% by volume, preferably between 10 (ten) and 30% (thirty)
by volume and more preferably about 20% (twenty) by volume of the
flow A1 passing through the lance fuel duct 2.
[0027] Additional examples of deflector 5 are continuous rings
(that is to say without the teeth-ring structure) with a flat or
conical shape. The deflector 5 can also not be present within the
lance fuel duct 2.
[0028] The wall 9 (that is to say the lance fuel duct's 2 outer
wall) has a flared terminal part 14 to deflect a part of the flow
B1 passing around the outer side of the wall 9, therefore around
the igniter lance 1. The flow B1 could be air and/or another
oxidizing medium; in certain embodiments could be air and/or
another oxidizing medium mixed with pulverized fossil fuels and/or
pulverized biomass.
[0029] In different examples, the electric igniter 3 does not
extend in the flared terminal part 14 (FIG. 1), or does extend into
the flared terminal part 14 (FIG. 2), or it can also be movable,
such that it is positioned in the flared terminal part 14 or
protruded further into the area 7 (that is to say into the furnace)
according to the needs.
[0030] In the example shown in FIG. 3 the flared terminal part 14
deflects a part of the flow B1 passing through the core air duct 16
of the burner 15; for example up to 80% (eighty) by volume,
preferably between 30 (thirty) and 70 (seventy) % by volume of the
flow pass through the core air duct 16. The flared terminal part 14
defines a cone having an opening angle B between 0 (zero) and 90
(ninety) degree, preferably between 30 (thirty) and 75
(seventy-five) degree. This design supports flame attachment and
stabilisation. The flared terminal part 14 can also not be present
within the terminal part of the wall 9.
[0031] Preferably, as shown in FIG. 3, the burner 15 houses the
igniter lance 1 within--as in the present example--the core air
duct 16 and that in turn is surrounded externally by the burner
fuel duct 17. This generates a symmetrical main burner flame by
igniting with the plasma formed by the electric igniter 3 the
pulverized fuel coming through the lance fuel duct 2 that in turn
ignites the pulverized fuel coming through the burner fuel duct 17.
By this method a compact and reliable ignition reaction can be
obtained.
[0032] Furthermore the burner could anyhow be different. For
example [0033] without core air duct, or [0034] with pulverized
main fuel supply through the burner centre, or [0035] with
pulverised fuel supply through the nozzles, and/or [0036]
rectangular burner without concentric flows.
[0037] In certain embodiments the one or more igniter lance(s) 1
could be housed within the one or more burner main fuel ducts, or
within the one or more combustion air ducts. In this way a compact
and reliable ignition reaction can be obtained for different kinds
burner types (e.g. round burner, rectangular burner, and other
industrial scale burners).
[0038] Preferably, the pulverized main fuel supplied through the
burner fuel duct 17 of the burner 15 and through the lance fuel
duct 2 of the igniter lance 1, are of identical fuel type and
quality, (e.g. bituminous coal, dry lignite, biomass, or other
fossil fuels); they could anyhow be different (e.g. bituminous coal
and dry lignite, bituminous coal and biomass, or other fossil fuels
and/or biomass combination) or combinations of or with any other
pulverized fuels).
[0039] The lance fuel duct 2 supplies sufficient energy for safe
and secure ignition of an industrial scale burner as required by
safety codes and standards as for example EN 12952, NFPA and GB
code.
[0040] The burner 15 can also be provided with one or more
additional air ducts for supplying air or another oxidizer such as
oxygen; FIG. 3 shows for example the burner 15 with the igniter
lance 1 housed within the core air duct 16 and this in turn is
housed within the burner fuel duct 17. Furthermore, two additional
air ducts 18 and 19 are provided and which include swirl generators
20.
[0041] In the following some examples for burner are described.
[0042] (1) The burner 15 has the igniter lance 1 housed within the
core air duct 16 and this is in turn housed within the burner fuel
duct 17; furthermore the burner fuel duct 17 is surrounded
externally by one or more air duct 18, 19.
[0043] (2) The burner 15 has the igniter lance 1 housed within the
burner fuel duct 17; furthermore the burner fuel duct 17 is
surrounded externally by one or more air duct 18, 19.
[0044] (3) The burner 15 has the igniter lance 1 housed within one
of the at least one air duct 18, 19.
[0045] (4) The burner 15 has the igniter lance 1 housed within each
air duct 18, 19.
[0046] The operation is described in the following for the burner
15 combined with the igniter lance 1; it can be easily translated
for other burner systems combined with the igniter lance 1.
[0047] At start-up, firstly, pulverized fuel is supplied through
the lance fuel duct 2 by transport air and/or another oxidizing
medium forming flow A1. The maximum amount of fuel that can be
transported by flow A1 is limited in accordance with valid boiler
safety codes and standards; in the present example it can be
limited to max 10% by weight of the total amount of pulverized fuel
supplied through the burner 15 at full load. The part flow A2,
which is a part of the flow A1, is deflected by the deflector 5
towards the previously formed plasma 4 in the area 7 and thereby
improves the ignition of the pulverised fuel. Another part of flow
A1, part flow A3, passes through the protrusions 8 (defining the
deflector 5) without being deflected and flows towards the area
7.
[0048] While passing through the plasma 4 the pulverized fuel is
ignited and generates an ignition flame 21 in the area 7 within the
furnace. The ignition flame 21 is generated by a sufficient amount
of the pulverized fuel to provide sufficient energy for safe and
secure ignition of the burner 15.
[0049] The part flow B2 (in this example core air), that is
diverted by the flared terminal part 14 towards the area 7,
supports the combustion process and generates a recirculation zone
that holds the ignition flame 21 in its position in area 7.
[0050] Once the ignition flame 21 is stable and has sufficient
energy for ignition of the burner 15, the fuel supply of burner 15
is activated and pulverized fuel is sent through the burner fuel
duct 17 and ignited by the ignition flame 21.
[0051] After ignition of the main fuel (i.e. pulverised fuel
supplied through the burner fuel duct 17) and the establishment of
a stable combustion, the fuel flow through the lance fuel duct 2
can either be stopped or continued as required. Furthermore,
operation of the electric ignitor 3 can be also stopped or
continued as required.
[0052] The present disclosure also refers to a method for operating
a burner (such as an industrial scale burner for example for a
power plant) having the igniter lance 1.
[0053] The method comprises: [0054] providing a plasma 4 by the
electric igniter 3, [0055] supplying pulverized fuel through the
lance fuel duct 2, [0056] igniting the pulverized fuel supplied
through the lance fuel duct 2 through the plasma 4 provided by the
electric ignitor 3, [0057] generating an ignition flame 21, [0058]
supplying pulverized fuel through the burner fuel duct 17, [0059]
igniting the pulverized fuel supplied through the burner fuel duct
17, through the ignition flame 21.
[0060] This method allows stable combustion and sufficient energy
for safe and secure ignition of the industrial scale burner 15.
[0061] Preferably, the deflector 5 faces a mouth 6 and deflects at
least a part of up to 25 (twenty-five) % by volume of the
pulverized fuel flowing through the lance fuel duct 2 towards the
plasma 4.
[0062] Naturally the features described may be independently
provided from one another.
[0063] In practice the materials used and the dimensions can be
chosen at will according to requirements and to the state of the
art.
* * * * *