U.S. patent application number 10/412940 was filed with the patent office on 2004-10-14 for injection lance for uniformly injecting a steam/ammonia mixture into a fossil fuel combustion stream.
Invention is credited to Rumen, Robert.
Application Number | 20040201142 10/412940 |
Document ID | / |
Family ID | 33131328 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040201142 |
Kind Code |
A1 |
Rumen, Robert |
October 14, 2004 |
Injection lance for uniformly injecting a steam/ammonia mixture
into a fossil fuel combustion stream
Abstract
An injection lance for injecting a homogeneous mixture of
steam/ammonia gas into a furnace having a flue gas (combustion)
stream moving therethrough to reduce nitrogen oxides therein. The
lance includes an outer and an inner tube. The outer end of the
inner tube is in communication with the outer tube while the outer
end of the outer tube is in communication with a source of
homogeneous steam/ammonia. The outer end of the inner tube sealably
embraces the exterior surface of the lance feed tube so that the
homogeneous steam/ammonia mixture being introduced into the outer
tube passes towards the inner end of the lance between the annulus
formed by the concentric outer and inner tubes. The homogeneous
steam/ammonia mixture is passed into the annular space in the inner
tube and then is discharged from the lance through discharge flow
control nozzles or ports which extend from the interior of the
inner tube to the exterior of the outer tube.
Inventors: |
Rumen, Robert; (East
Brunswick, NJ) |
Correspondence
Address: |
Diane Dunn McKay, Esq.
Mathews, Collins, Shepherd & McKay, P.A.
100 Thanet Circle, Suite 306
Princeton
NJ
08540
US
|
Family ID: |
33131328 |
Appl. No.: |
10/412940 |
Filed: |
April 14, 2003 |
Current U.S.
Class: |
266/225 |
Current CPC
Class: |
F23J 7/00 20130101; B01D
53/79 20130101; C21C 5/5217 20130101; B01D 53/56 20130101; C21C
5/4606 20130101; F23J 15/003 20130101; F23C 2900/07021 20130101;
Y02P 10/216 20151101; Y02P 10/20 20151101; B01D 2251/2062
20130101 |
Class at
Publication: |
266/225 |
International
Class: |
C21C 005/32 |
Claims
We claim:
1. An injection lance comprising: an outer tube having closed inner
and outer ends; an inner tube centrally positioned in said outer
tube, said inner tube having inner and outer ends, said inner end
of said inner tube being open, said inner end of said inner tube
being spaced apart from said inner end of said outer tube, said
inner tube being in fluid communication with a feed mixture; an
interior surface of said outer tube and an exterior surface of said
inner tube forming an annulus for defining a first passageway; an
interior surface of said inner tube defining a second passageway
between said annulus and an interior of said inner tube through
said inner end of said inner tube; and at least one discharge
orifice port extending from the interior surface of said inner tube
to the exterior surface of said outer tube, wherein said feed
mixture passes from said outer end of said inner tube towards said
inner end of said outer tube in said first passageway and then
passes into said interior of said inner tube in said second
passageway and is discharged from said discharge ports.
2. The injection lance of claim 1 wherein said feed mixture is a
mixture of steam and ammonia.
3. The injection lance of claim 2 wherein said feed mixture is
homogenous.
4. The injection lance of claim 2 wherein said ammonia is selected
from the group consisting of anhydrous ammonia, aqueous ammonia or
urea conversion ammonia.
5. The injection lance of claim 2 wherein the feed mixture further
comprises an additional gas to lower the optimum reaction
temperature.
6. The injection lance of claim 5 wherein said additional gas is
hydrogen or methane.
7. The injection lance of claim 1 further comprising a lance feed
tube receiving said feed mixture and a seal between said lance feed
tube and said inner tube.
8. The injection lance of claim 7 wherein said lance feed tube
includes a plurality of openings to discharge said feed mixture
into said first passageway.
9. The injection lance of claim 1 wherein said inner tube includes
at least one slip tube to absorb thermal expansion between said
outer tube and said inner tube therein.
10. The injection lance of claim 1 wherein said inner tube includes
a plurality of slip tubes to absorb thermal expansion between said
outer tube and said inner tube therein.
11. The injection lance of claim 1 further comprising at least one
orifice insert being received in said at least one discharge
orifice port.
12. The injection lance of claim 11 wherein said orifice insert has
an aperture therein.
13. The injection lance of claim 12 wherein said aperture is
variable.
14. The injection lance of claim 11 wherein said orifice insert is
solid.
15. The injection lance of claim 11 wherein said discharge orifice
port and said orifice insert have corresponding tapered sides.
16. The injection lance of claim 11 wherein said orifice insert is
removable.
17. The injection lance of claim 16 wherein said orifice insert
includes at least one aperture for receiving a pin at one end of an
orifice insert tool, said orifice insert tool including apertures
at a second end thereof.
18. The injection lance of claim 1 wherein said outer tube further
comprises a mating flange and reducing fitting at said outer end of
said outer tube.
19. The injection lance of claim 2 wherein the steam creates an
oxygen-deprived atmosphere within said injection lance to retard or
hinder the thermal oxidation of the ammonia vapor normally found in
a high temperature oxygen rich atmosphere.
20. A combination comprising: a furnace or combustion process
having a flue gas stream moving therethrough; an outer tube having
closed inner and outer ends; an inner tube centrally positioned in
said outer tube, said inner tube having inner and outer ends, said
inner end of said inner tube being open, said inner end of said
inner tube being spaced apart from said inner end of said outer
tube, said inner tube being in fluid communication with a feed
mixture; an interior surface of said outer tube and an exterior
surface of said inner tube forming an annulus for defining a first
passageway; an interior surface of said inner tube defining a
second passageway between said annulus and an interior of said
inner tube through said open inner end of said inner tube; and at
least one discharge orifice port extending from the interior
surface of said inner tube to the exterior surface of said outer
tube, wherein said feed mixture passes from said outer end of said
inner tube towards said inner end of said outer tube in said first
passageway and then passes into said interior of said inner tube in
said second passageway and is discharged from said discharge
ports.
21. The combination of claim 20 wherein said feed mixture is a
mixture of steam and ammonia.
22. The combination of claim 21 wherein said feed mixture is
homogenous.
23. The combination of claim 21 wherein said ammonia is selected
from the group consisting of anhydrous ammonia, aqueous ammonia or
urea conversion ammonia.
24. The combination of claim 21 wherein the feed mixture further
comprises an additional gas to lower the optimum reaction
temperature.
25. The combination of claim 24 wherein said additional gas is
hydrogen or methane.
26. The combination of claim 20 further comprising a lance feed
tube receiving said feed mixture, and a seal between said lance
feed tube and said inner tube.
27. The combination of claim 26 wherein said lance feed tube
includes a plurality of openings to discharge said feed mixture
into said first passageway.
28. The combination of claim 20 wherein said inner tube includes at
least one slip tube to absorb thermal expansion between said outer
tube and said inner tube therein.
29. The combination of claim 20 wherein said inner tube includes a
plurality of slip tubes to absorb thermal expansion between said
outer tube and said inner tube therein.
30. The combination of claim 20 further comprising at least one
orifice insert being received in said at least one discharge
orifice port.
31. The combination of claim 30 wherein said orifice insert has an
aperture therein.
32. The combination of claim 30 wherein said aperture is
variable.
33. The combination of claim 30 wherein said orifice insert is
solid.
34. The combination of claim 30 wherein said discharge orifice port
and said orifice insert have corresponding tapered sides.
35. The combination of claim 20 wherein said orifice insert is
removable.
36. The combination of claim 35 wherein said orifice insert
includes at least one aperture for receiving a pin at one end of an
orifice insert tool, said orifice insert tool including apertures
at a second end thereof.
37. The combination of claim 20 wherein said outer tube further
comprises a mating flange and reducing fitting at said outer end of
said outer tube.
38. The combination of claim 20 further comprising a mechanical
retract/insertion mechanism for moving said lance into said furnace
and outwardly therefrom attached to said mating flange.
39. The combination of claim 38 wherein said mechanical
insertion/retract mechanism allows for the rotation of the inserted
said injection lance about its centroidal axis to allow for
optimizing its performance.
40. The combination of claim 21 wherein the steam creates an
oxygen-deprived atmosphere within said injection lance to retard or
hinder the thermal oxidation of the ammonia vapor normally found in
a high temperature oxygen rich atmosphere.
41. The combination of claim 20 wherein said furnace or combustor
includes a vertical or horizontal wall and wherein said injection
lance extends substantially horizontally or vertically through said
furnace wall.
42. The combination of claim 20 wherein said lance has a
longitudinal axis which is substantially transversely disposed with
respect to the direction of movement of the flue gas stream moving
through said furnace.
43. The combination of claim 42 wherein said discharge orifice
ports are oriented on said lance so that said feed mixture is
discharged into the flue gas stream substantially transversely with
respect thereto.
44. The combination of claim 42 wherein said discharge orifice
ports are oriented on said lance so that said feed mixture is
discharged into the flue gas stream but can be located to discharge
in an orientation to achieve optimized performance.
45. The combination of claim 20 wherein the spacing of said inner
tube with respect to said outer tube is constructed and arranged
such that said feed mixture being discharged into the flue gas
stream will be approximately the same along the length of said
lance.
46. The combination of claim 20 wherein said annulus and the
passing flow of said feed stream cools said outer tube from the
flue gas.
47. A method for uniformly injecting a feed stream into a fuel
combustion stream comprising the steps of: mixing steam with
ammonia to form said feed stream; introducing said feed stream into
an injection lance, said injection lance comprising an outer tube
having closed inner and outer ends; an inner tube centrally
positioned in said outer tube, said inner tube having inner and
outer ends, said inner end of said inner tube being open, said
inner end of said inner tube being spaced apart from said inner end
of said outer tube said inner tube being in fluid communication
with said feed mixture; an interior surface of said outer tube and
an exterior surface of said inner tube forming an annulus for
defining a first passageway; an interior surface of said inner tube
defining a second passageway between said annulus and an interior
of said inner tube through said open inner end of said inner tube;
and at least one discharge orifice port extending from the interior
surface of said inner tube to the exterior surface of said outer
tube, said feed mixture passes from said outer end of said inner
tube towards said inner end of said outer tube in said first
passageway and then passes into said interior of said inner tube in
said second passageway; and discharging said feed stream from said
discharge ports into said fossil fuel combustion stream.
48. The method of claim 47 wherein said feed mixture is a mixture
of steam and ammonia.
49. The method of claim 48 wherein said feed mixture is
homogenous.
50. The method of claim 48 wherein said ammonia is selected from
the group consisting of anhydrous ammonia, aqueous ammonia or urea
conversion ammonia.
51. The method of claim 48 wherein the feed mixture further
comprises an additional gas to lower the optimum reaction
temperature.
52. The injection lance of claim 51 wherein said additional gas is
hydrogen or methane.
53. The method of claim 47 wherein said lance further comprises a
lance feed tube receiving said feed mixture, and a seal between
said lance feed tube and said inner tube.
54. The method of claim 47 wherein said lance feed tube includes a
plurality of openings to discharge said feed mixture into said
first passageway.
55. The method of claim 47 wherein said inner tube includes at
least one slip tube to absorb thermal expansion between said outer
tube and said inner tube therein.
56. The method of claim 47 wherein said lance further comprises: at
least one orifice insert being received in said at least one
discharge orifice port.
57. The method of claim 47 wherein said lance further comprises
wherein said orifice insert has an aperture therein.
58. The method of claim 47 wherein said lance further comprises
wherein the steam creates an oxygen-deprived atmosphere within said
injection lance to retard or hinder the thermal oxidation of the
ammonia vapor normally found in a high temperature oxygen rich
atmosphere.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to a nitrogen oxide (NOx)
reduction process termed SNCR. More particularly, the injection
lance of this invention is utilized for reducing NOx emitted from
fossil fuel fired combustion processes. More particularly, the
invention permits the uniform injection of a reagent (anhydrous,
aqueous ammonia, or urea to ammonia conversion) and mixing steam
into the furnace's flue gas combustion stream in a location which
is between about 1600 to about 1900 degrees F. without the use of
an additional temperature enhancing gas and about 1300 to about
1900 degrees F. with the use of a temperature enhancing gas.
[0003] 2. Description of the Related Art
[0004] Selective, non-catalytic nitrogen oxide reduction (SNCR)
processes have been used for many years to reduce the oxides of
nitrogen in combustion processes. SNCR has been used for the
reduction of NOx to meet regulatory limits by a chemical process
after combustion has already taken place. Numerous NOx reduction
methods modify the combustion process itself by installing new
burners and combustion-related equipment. On some boiler types, it
is difficult, or impossible, to modify the combustion process
equipment. It may also be desirable to lower NOx to levels below
those obtainable by burner related equipment alone. In these cases,
it may be desirable to reduce the NOx after it has been formed,
rather than to attempt a different method of combustion.
[0005] In order to inject the SNCR reagent into the combustion
stream, penetrations of the furnace must be accomplished.
Penetrations require modifications to the furnace water wall tubes
and the penetrations are expensive. Minimizing the number of boiler
penetrations is important to the cost of installation on a SNCR
system.
[0006] SNCR utilizes a reagent to create a localized reducing
atmosphere to convert nitrogen oxide in the furnace to a nitrogen
molecule. Inasmuch as this chemical reagent must be continuously
injected into the boiler cavity, minimizing the cost of the reagent
is important to the cost of operation of the furnace's SNCR system.
It has been found that anhydrous ammonia is a more economical
reagent than most competing reagents in the SNCR process. Due to
the inherent personnel and community health risks associated with
anhydrous ammonia; aqueous ammonia, or urea to ammonia conversion
is sometimes utilized.
[0007] During the injection of the reagent into the furnace cavity,
it is important that the reagent be uniformly mixed and thoroughly
distributed in the furnace's flue gas stream temperature where the
non-catalytic reduction reaction can occur. When injecting ammonia
into the boiler, it is important that it not come into contact with
an extremely hot surfaces (over approximately 900 degree F.), which
will cause the ammonia to begin to thermally disassociate into
nitrogen molecules, or will create even more nitrogen oxides when
the disassociation is in the presence of an oxygen-rich
atmosphere.
[0008] When ammonia is injected into the furnace flue gas stream as
a vapor, the ammonia molecule is ready to begin the non-catalytic
process without any additional vaporization which will reduce the
formation of ammonia "slip" as an emission product. Previous
testing has shown that ammonia also tends to create less global
warming gases such as nitrous oxide (N.sub.2O) and carbon dioxide
(CO.sub.2) then other reagents.
[0009] In those situations where the anhydrous, aqueous ammonia, or
urea to ammonia conversion reagents are mixed with mixing air, it
is important to reduce and limit the amount of mixing air, since
the mixing air tends to increase the amount of available oxygen to
combine with the disassociated nitrogen and create additional
nitrogen oxides. Also, because the air is injected after the
combustion process, it reduces the overall boiler efficiency.
[0010] Certain of the prior art utilizing reagent injection
equipment does not permit the injection equipment to be inspected
or modified while the boiler is in service. This is especially true
on coal-fired furnaces, because the reagent is injected into a flue
gas stream which contains "sticky" ash particles which could plug
the variable, controllable injection ports and render the SNCR
process ineffective.
[0011] U.S. Pat. No. 5,681,536 describes an injection lance for
injecting a mixture of air and anhydrous ammonia into a boiler
having a flue gas stream moving therethrough to reduce nitrous
oxides therein. The lance includes outer, intermediate and inner
tubes. The outer end of the inner tube is in communication with a
source of anhydrous ammonia. The outer end of the outer tube is in
communication with a source of mixing air. The outer end of the
intermediate tube seals the exterior surface of the inner tube so
that air being introduced into the outer tube passes toward the
inner end of the lance between the outer and intermediate tubes.
The mixing air and anhydrous ammonia are passed into the space
between the inner tube and the intermediate tube and then are
discharged through discharge nozzles from the interior of the
intermediate tube to the exterior of the outer tube. This patent
has the shortcoming that the use of heated air can cause a chemical
reaction with ammonia to form byproducts of nitrogen (NO.sub.x) and
the mixing of air and ammonia internally is ineffective.
[0012] It is desirable to provide an improved injection lance for
injecting a mixture of ammonia and steam into a furnace having a
flue gas stream to reduce the nitrogen oxides therein providing
optimized operating characteristics.
SUMMARY OF THE INVENTION
[0013] The present invention relates to an injection lance for
injecting a homogeneous feed mixture, such as steam and ammonia,
into a furnace having a flue gas stream moving therethrough to
reduce the nitrogen oxides therein. The steam and ammonia are
joined external to the injection lance to create a homogenous
mixture to be introduced in the injection lance. By using steam,
instead of mixing air, the thermal and oxidizing reduction of
ammonia into NOx is drastically reduced or eliminated. The
homogeneous steam/ammonia mixture which is preheated before
entering the flue gas stream has a less detrimental effect on the
overall furnace efficiency and has a lesser potential for droplet
impingement corrosion on heat transfer surfaces. The term ammonia
refers to a nitrogeneous compound such as anhydrous, aqueous, or
urea to ammonia conversion ammonia.
[0014] The injection lance comprises an outer tube and an inner
tube. The lance of the present invention comprises an elongated
outer tube having closed inner and outer ends. The outer tube is in
communication, adjacent its outer end, with a source of a feed
mixture, such as a homogeneous steam/ ammonia mixture. An elongated
inner tube, having inner and outer ends, is centrally positioned
coaxially in the outer tube. The inner tube is in fluid
communication, adjacent its outer end with the feed mixture. The
outer end of the inner tube sealably embraces the lance feed tube
inwardly of the location where the feed mixture enters the outer
tube. The feed mixture passes between an annulus and formed by the
outer tube and the inner tube and passes towards the inner end of
the outer tube and into the open inner end of the inner tube. The
inner tube can include an expansion mechanism provided thereon. A
plurality of spaced-apart discharge ports or nozzles extend from
the interior of the inner tube to the exterior of the outer tube so
that the feed mixture present in the inner tube will be discharged
into the flue gas stream substantially transversely with respect to
the flow of gas.
[0015] The present invention provides an improved injection lance
for injecting a homogeneous mixture of steam and ammonia into a
combustion stream having a flue gas stream moving therethrough to
reduce nitrogen oxides therein. The injection lance prohibits the
ammonia from coming into contact with extremely hot surfaces in an
air (oxygen-rich) atmosphere. The injection lance treats a major
quantity of the furnace's flue gas with only a single boiler
penetration.
[0016] The injection lance can be easily and automatically inserted
or withdrawn from the furnace, such as by using standard industry
devices, thus allowing for optimum temperature selection for
ammonia injection, stopping the injection of the steam/ammonia
mixture when the optimum temperature window does not exist in the
furnace. This also allows inspection of the lance and its orifice
ports, and repositioning (tuning/optimizing) of the variable,
controllable orifice inserts along the length or radial axis of the
lance without interrupting the combustion operation.
[0017] The injection lance of the present invention can be
installed on the furnace without extensive modification
thereof.
[0018] The invention will be more fully described by reference to
the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a plan view of the injection lance in accordance
with the teachings of the present invention;
[0020] FIG. 2 is an elevation view of the injection lance of the
present invention;
[0021] FIG. 3 is a perspective view of the injection lance of the
present invention with a portion thereof cut away to more fully
illustrate the invention;
[0022] FIG. 4 is an elongated sectional view taken through the
injection lance;
[0023] FIG. 5 is a sectional view seen on Section A-A of FIG.
4;
[0024] FIG. 6 is a sectional view seen on detail 1 of FIG. 4;
[0025] FIG. 7A is a sectional view seen on section A-A of FIG.
6;
[0026] FIG. 7B is a sectional view seen on section B-B of FIG.
6;
[0027] FIG. 8 is a sectional view seen on detail 2 of FIG. 4;
[0028] FIG. 9 is a sectional view of an orifice port;
[0029] FIG. 10A is a sectional view of an orifice insert received
in the orifice port;
[0030] FIG. 10B is a top plan view of the orifice insert;
[0031] FIG. 11A is a side sectional view of an orifice insert
tool;
[0032] FIG. 11B is a bottom plan view of the orifice insert tool
shown in FIG. 11A;
[0033] FIG. 11C is a top plan view of the orifice insert tool shown
in FIG. 11A;
[0034] FIG. 12 is a sectional view seen on detail 3 of FIG. 4;
[0035] FIG. 13 is a sectional view seen on detail 4 of FIG. 4;
and
[0036] FIG. 14 is a sectional view seen on detail 5 of FIG. 4.
DETAILED DESCRIPTION
[0037] Reference will now be made in greater detail to a preferred
embodiment of the invention, an example of which is illustrated in
the accompanying drawings. Wherever possible, the same reference
numerals will be used throughout the drawings and the description
to refer to the same or like parts.
[0038] FIGS. 1-4 illustrate injection lance 10 in accordance with
the teachings of the present invention. Injection lance 10 includes
outer tube 18 having inner end 20 and outer end 22. Outer tube 18
includes interior surface 24 and exterior surface 26. Inner tube 28
is positioned centrally and coaxially with outer tube 18. Inner
tube 28 has inner end 30 and outer end 32.
[0039] Outer end 32 of inner tube 28 is positioned outwardly of the
furnace wall, as illustrated in FIG. 4, and is in communication
with a source of feed mixture 29. Feed mixture 29 is adapted to be
passed along the length of the lance feed tube 38 toward outer end
32 of inner tube 28. Feed mixture 29 can be a steam and a
nitrogenous compound mixture. The nitrogenous compound can be
ammonia (NH.sub.3) or a compound that reacts to produce ammonia,
such as urea. The source of ammonia can be anhydrous ammonia or
aqueous ammonia. Feed mixture 29 can be homogenous. Feed mixture 29
can include additional gases, such as inert gases for optimizing
the atmospheric condition. The use of an additional temperature
enhancing gas reduces the operating condition to about 1300.degree.
F. to about 1900.degree. F. Examples of additional gases include
various hydrogen based gases such as hydrogen or methane.
[0040] For purposes of description, inner tube 28 will be described
as including an interior surface 34 and an exterior surface 36, as
shown in FIG. 5. Outer end 32 of inner tube 28 is provided with end
seal 27, as illustrated in FIG. 4 and FIG. 6. Outer end 32 of inner
tube 28 is sealably embracing by the means of end seal 27 at
exterior surface 37 of lance feed tube 38. Inner end 40 of lance
feed tube 38 is provided with a plurality of discharge openings 39,
which causes the homogeneous steam/ammonia mixture ammonia to be
forced in the direction of the arrows. Discharge opening can be
provided at various locations in lance feed tube as shown in FIGS.
7A-7B. Feed mixture 29 exits discharge openings 39 and flows into
annulus area 48 positioned between interior surface 24 of outer
tube 18 and exterior surface 36 of inner tube 28, as shown in FIG.
6. Other means could be utilized as long as the feed mixture 29 is
directed to annulus area 48 created by tube 18 and inner tube 28,
once feed mixture 29 has been discharged from inner end 40 of lance
feed tube 38.
[0041] As shown in FIG. 8, inner end 30 of inner tube 28 is spaced
from inner end 20 of outer tube 18. Inner end 30 of inner tube 28
is open to provide a second passageway between annulus area 48 into
the interior of inner tube 28.
[0042] A plurality of discharge orifice ports 54 are provided, as
illustrated in FIGS. 4-5, and extend from interior surface 34 of
inner tube 28 to exterior surface 26 of tube 18. Discharge orifice
ports 54 are capable of accepting orifice inserts 55 or being
plugged to control the amount and distribution of the feed mixture
to optimize the removal of NOx from the flue gas stream. Discharge
orifice ports 54 can have a nozzle shape, as shown in FIG. 3.
[0043] Discharge orifice ports 54 can have tapered sides 53, as
shown in FIG. 9. Orifice inserts 55 can have a variable aperture 52
therein or provide a solid plug, as shown in FIGS. 10A-10B. Orifice
inserts 55 can be inserted and removed from discharge ports 54.
Orifice inserts 55 can have tapered sides 51 corresponding to
tapered sides 53 of discharge orifice ports 54.
[0044] Orifice inserts 55 can be inserted or removed from discharge
orifice ports using orifice insert tool 59 shown in FIGS. 11A-11C.
Pins 60 of orifice insert tool 59 are inserted in apertures 57 of
orifice insert. Pins 60 can be press fitted or replaceable to
orifice insert tool 59. Top 61 of orifice insert tool 59 has
protrusion 62. For example, protrusion 62 can have a hexagonal
shape. Protrusion 62 can be rotated with a conventional tool such
as a hex wrench for removal of orifice inserts 55 from orifice port
54.
[0045] After insertion of orifice insert tool 59 into insert 55,
inner tube 28 can be provided with a plurality of slip tubes 56, as
shown in FIG. 3 and FIG. 12. Slip tubes 56 permit movement of inner
tube 28 with respect to outer tube 18. Slip tubes 56 are preferably
provided inasmuch as outer tube 18 is exposed to a greater
temperature resulting from exposure to the furnace than inner tube
28 resulting in greater expansion of outer tube 18. Slip tubes 56
allow expansion of inner tube 28 to be comparable to expansion of
outer tube 18. It should be noted, however, that slip tubes 56 may
not be needed for relatively short injection lances 10.
[0046] Outer tube 18 is provided with mating flange 64 which
includes a reducing fitting 65 to enable the injection lance 10 to
be retrofitted to a retract mechanism, as shown in FIG. 13. For
example, mating flange 64 can be a conventional mechanism as
manufactured by Clyde Bergmann as a lance flange. Retract
mechanisms can be a conventional mechanism for coupling to mating
flange 64.
[0047] Injection lance 10 extends through the opening 70 in furnace
water wall 72 of furnace 73, as shown in FIG. 14. Sootblower drive
74 is adapted to move the injection lance 10 inwardly into the flue
gas stream, outwardly, or rotationally therefrom when it is desired
to control the injection for NOx control, inspect the condition of
the lance, when it is desired to perform maintenance thereon, or to
reconfigure orifice inserts 55 to achieve optimum NOx reduction and
minimum ammonia slip performance.
[0048] In operation, feed mixture 29 is introduced into inner end
30 of inner tube 28 after traveling thru annulus area 48 formed by
outer tube 18 and inner tube 28. Feed mixture 29 is then introduced
to the interior area passageway of inner tube 28. Feed mixture 29
is then discharged through discharge orifice ports 54 and orifice
inserts 55 into the flue gas stream where the mixture reacts with
the nitrogen oxides therein to reduce the level thereof.
[0049] The longitudinal axis of injection lance 10 can be disposed
transversely with respect to the flow of the flue gases whether the
flue gases are moving horizontally, vertically or a combination
thereof. Discharge orifice ports 54 are positioned on injection
lance 10 so that the feed mixture is directed into the flue gases
at an optimum angle thereto. Thus, if the flue gases are moving
vertically upwardly through the furnace, the longitudinal axes of
the discharge orifice ports 54 will be horizontally disposed.
Conversely, if the flue gases are moving horizontally through the
furnace, the longitudinal axes of discharge orifice ports 54 will
be vertically disposed. If the flue gas is moving at an angle
through the furnace, the longitudinal axes of discharge orifice
ports 54 can be adjusted to the optimum angle thereto.
[0050] It is also important to note that inner tube 28 is somewhat
insulated from the hot combustion gases due to the fact that outer
tube 18 is positioned around the inner tube. Thus, the feed mixture
is removing from outer tube 18 the heat of the flue gas until the
feed mixture is discharged into the gas stream. Injection lance 10,
by its design, provides a homogeneous mixture which is
approximately the same temperature at all discharge orifice ports
54 along the length of injection lance 10.
[0051] It is to be under stood that the above-described embodiments
are illustrative of only a few of the many possible specific
embodiments which can represent applications of the principles of
the invention. Numerous and varied other arrangements can be
readily devised in accordance with these principles by those
skilled in the art without departing from the spirit and scope of
the invention.
* * * * *