U.S. patent application number 16/108602 was filed with the patent office on 2019-02-28 for combustion plant and method for operating a combustion plant.
This patent application is currently assigned to Martin GmbH fuer Umwelt- und Energietechnik. The applicant listed for this patent is Martin GmbH fuer Umwelt- und Energietechnik. Invention is credited to Ulrich MARTIN, Martin MURER, Robert VON RAVEN.
Application Number | 20190063745 16/108602 |
Document ID | / |
Family ID | 62750735 |
Filed Date | 2019-02-28 |
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United States Patent
Application |
20190063745 |
Kind Code |
A1 |
MARTIN; Ulrich ; et
al. |
February 28, 2019 |
COMBUSTION PLANT AND METHOD FOR OPERATING A COMBUSTION PLANT
Abstract
A special distribution of nozzles in the flue gas outlet and
their alignment make it possible to guide the flue gas along a wavy
line. The addition of combustion air for primary air and secondary
air can be variably distributed during operation of the combustion
plant, for example so as to also keep the burnout per unit of time
constant while maintaining a constant combustion air ratio.
Inventors: |
MARTIN; Ulrich; (Muenchen,
DE) ; VON RAVEN; Robert; (Seeshaupt, DE) ;
MURER; Martin; (Muenchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Martin GmbH fuer Umwelt- und Energietechnik |
Muenchen |
|
DE |
|
|
Assignee: |
Martin GmbH fuer Umwelt- und
Energietechnik
Muenchen
DE
|
Family ID: |
62750735 |
Appl. No.: |
16/108602 |
Filed: |
August 22, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23C 2201/101 20130101;
F23J 7/00 20130101; F23B 1/18 20130101; F23L 9/02 20130101 |
International
Class: |
F23L 9/02 20060101
F23L009/02; F23J 7/00 20060101 F23J007/00; F23B 30/00 20060101
F23B030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2017 |
DE |
10 2017 008 123.9 |
Claims
1. A combustion plant with a flue gas outlet, which has nozzles on
opposing sides of the flue gas outlet, so as to inject a fluid into
the flue gas, wherein the nozzles are arranged and aligned in such
a way as to move the flue gas in the flue gas outlet back and forth
along a wavy line.
2. The combustion plant according to claim 1, wherein the fluid is
a gas.
3. The combustion plant according to claim 2, wherein the gas is
air.
4. The combustion plant according to claim 2, wherein the gas is
steam.
5. The combustion plant according to claim 1, wherein the wavy line
has three, and preferably more than four reversal points.
6. The combustion plant according to claim 1, wherein the primary
nozzle direction of the two nozzles arranged on opposing sides of
the flue gas outlet lies at an angle of at least 5.degree.,
preferably of more than 10.degree., from a line connecting the
nozzles.
7. The combustion plant according to claim 1, wherein the primary
nozzle direction of a nozzle deviates from the shortest connection
to the opposing side of the flue gas outlet by an angle of at least
5.degree., preferably of more than 10.degree..
8. The combustion plant according to claim 1, wherein the primary
nozzle direction of at least one nozzle deviates from a horizontal
plane in the flue gas outlet by an angle of at least 5.degree.,
preferably of more than 10.degree..
9. The combustion plant according to claim 1, wherein the
combustion plant has a furnace grate for combustion.
10. The combustion plant according to claim 9, wherein the flue gas
outlet of the furnace grate expands in the direction of flow of the
flue gas.
11. The combustion plant according to claim 9, wherein the flue gas
outlet has a lower area and an upper area, wherein the access from
the furnace grate to the flue gas outlet in the lower area is
arranged offset to the upper area.
12. The combustion plant according to claim 9, wherein at least one
nozzle is arranged above the furnace grate in the direction of flow
of the flue gas before the flue gas outlet, so as to inject fluid
into the flue gas.
13. A method for operating a combustion plant according to claim 1,
in which at least a portion of the combustion air is added to the
flue gas through nozzles arranged on opposing sides of the flue gas
outlet, wherein the combustion air is added as primary combustion
air and secondary combustion air or as secondary combustion air
during operation of the combustion plant at several varyingly
different addition points.
14. The method according to claim 13, wherein the combustion air
ratio is held constant.
15. The method according to claim 13, wherein the combustion air is
added distributed to the nozzles and grate.
16. The method according to claim 13, wherein the distribution of
partial volume flows to these nozzles is controllably varied.
17. The method according to claim 13, wherein, during operation of
the combustion plant, the combustion air is distributed to the
individual addition points optimized for NO.sub.x, CO and/or
O.sub.2.
18. The method according to claim 13, wherein the distribution of
combustion air is split among the nozzles in the flue gas outlet in
such a way as to achieve a nearly constant burnout (gas and/or
solid burnout) per unit time.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Applicant claims priority under 35 U.S.C. .sctn. 119 of
German Application No. 10 2017 008 123.9 filed on Aug. 30, 2017,
the disclosure of which is incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The invention relates to a combustion plant with a flue gas
outlet, which has nozzles on opposing sides of the flue gas outlet,
so as to meter a fluid into the flue gas. In addition, the
invention relates to a method for operating a combustion plant, in
which at least a portion of the combustion air is added to the flue
gas through nozzles arranged on opposing sides of the flue gas
outlet.
2. Description of the Related Art
[0003] In a combustion plant, it is known not just to vary the
primary air, but also to add the secondary air to the flue gas
through different nozzles. The addition of fluids in the secondary
combustion area serves to swirl the flue gases, and is intended to
produce a homogeneous mixing of the flue gas and the secondary air
added through the nozzles. In practice, a strong swirling is
achieved via special nozzle formations, which leads to a mixing of
the added secondary air with the flue gas. For example, this is
described in DE 19 47 164 A, CN 102 620 285 A and US 2004/0 185 399
A1. The objective here is to keep the flue gas away from the walls
and optimally mix it in the center of the flue gas outlet through
suitably arranged nozzles and gas flows adjusted thereto.
SUMMARY OF THE INVENTION
[0004] The object of the invention is to further develop such a
combustion plant.
[0005] This object is achieved with a generic combustion plant, in
which the nozzles are arranged and aligned in such a way as to move
the flue gas in the flue gas outlet back and forth along a wavy
line.
[0006] The invention is based on the knowledge that the nozzles can
be used not just for swirling purposes, but can also be arranged in
such a way that the flue gas moves along a wavy line in the flue
gas outlet. In other words, a single flue gas particle is not
guided in the flue gas outlet coming from the furnace grate along a
straight line or spiral furnace grate. The particle is also not
guided through the flue gas accompanied by swirling so as to be
intensively mixed with secondary air.
[0007] According to the invention, the flue gas particles flow on a
defined wavy line through the flue gas outlet. As a result,
essentially all particles have a longer retention time in the flue
gas outlet than would be possible given a straight through-flow.
While individual flue gas particles have an especially long path
inside of the flue gas outlet when swirling, and other particles
flow especially quickly through the flue gas outlet, guiding the
flue gas according to the invention causes essentially all
particles to traverse a longer path in the flue gas outlet. This
increases the retention time of the particles in the flue gas
outlet, and all particles have a defined retention time on a
defined path. Guidance along the wavy line is possible, since hot
flue gases have a viscous consistency, and can thus be guided on a
path through the nozzles. This results in a reproducible, uniform
treatment of the flue gas, and, in particular in edge areas of the
flue gas outlet, prevents flue gas particles from flowing in
straight strands along a relatively straight line through the flue
gas outlet, while other particles remain in the flue gas outlet for
a very long time due to swirling.
[0008] According to the invention, the nozzles are not used for
swirling as in prior art, but rather are specifically aligned in
such a way that the flue gases flow along a wavy line through the
metered in fluid, thereby increasing the retention time inside of
the flue gas outlet.
[0009] In order to guide the flue gases along a wavy line,
pressure, volume flow and alignment along with nozzle formation
must be specially adjusted. Depending on the geometric formation of
the flue gas outlet, the nozzle parameters can be set in simple
tests in such a way as to achieve a defined wavy line. This wavy
line should have at least three, and preferably even more than
four, reversal points.
[0010] The added fluid can also be a liquid that as a rule
evaporates when entering into the flue gas outlet. It is
advantageous that a gas be added as the liquid. For example, this
gas can be air or steam.
[0011] Known nozzles in flue gas outlets are arranged in the flue
gas outlet in such a way that the nozzle is aligned perpendicular
to the wall of the flue gas outlet in which it is arranged.
[0012] However, it is advantageous for the solution underlying the
invention for the primary nozzle direction of the two nozzles
arranged on opposing sides of the flue gas outlet to lie at an
angle of at least 5.degree., preferably of more than 10.degree.,
from a line connecting the nozzles.
[0013] In particular if no other nozzle lies opposite the nozzle,
it is advantageous for the primary nozzle direction of a nozzle to
deviate from the shortest connection to the opposing side of the
flue gas outlet by at least 5.degree., preferably by more than
10.degree..
[0014] In relation to a horizontal line, it is advantageous for the
primary nozzle direction of at least one nozzle to deviate from a
horizontal plane in the flue gas outlet by at least 5.degree.,
preferably by more than 10.degree..
[0015] The invention is suitable in particular for combustion
plants which exhibit a furnace grate for combustion.
[0016] It is here advantageous for the flue gas outlet of the
furnace grate to expand in the direction of flow of the flue gas. A
combustion plant in which the flue gas outlet expands from the
furnace grate in the direction of flue gas flow is essential to the
invention even independently of the features of a combustion plant
mentioned above.
[0017] Expanding the flue gas outlet in this way leads to an
inverted nozzle, and hence slows down the flow in the flue gas
outlet. Either cumulatively or alternatively to moving the flue
gases along a wavy line, it is thus proposed that the flow rate of
the flue gases in the flue gas outlet be decreased by expanding the
flue gas outlet. A flue gas outlet expansion is understood as a
cross section of the flue gas outlet that expands in the direction
of flue gas flow. The direction of flue gas flow given a wavy line
is here understood as the connection between reversal points of the
wave.
[0018] In another embodiment of the combustion plant that is also
relevant to the invention even independently of the aforementioned
features, the flue gas outlet has a lower and upper area, wherein
the access from the furnace grate to the flue gas outlet in the
lower area is arranged offset to the upper area.
[0019] While the flue gases in the flue gas outlet essentially flow
toward the top and the retention time in the flue gas outlet can be
increased by moving the flue gases along a wavy line and/or by
expanding the flue gas outlet, the retention time in the flue gas
outlet can also be increased while keeping the height of the flue
gas outlet unchanged by displacing the access from the furnace
grate to the flue gas outlet to the remaining flue gas outlet.
[0020] A special embodiment provides that at least one nozzle be
arranged above the furnace grate in the direction of flow of the
flue gas before the flue gas outlet, so as to inject fluid into the
flue gas.
[0021] The object underlying the invention is also achieved with a
generic method in which the combustion air is added as primary
combustion air and secondary combustion air or as secondary
combustion air during operation of the incinerator at several
varyingly different addition points. While the addition of
combustion air is usually optimized and no longer changed during
operation of the incinerator, the invention proposes that the
distribution of combustion air to different addition points be
varied during operation of the incinerator.
[0022] It is indeed known for combustion plants to vary the primary
air in the area of the furnace grate according to an optical
analysis of combustion on the grate transverse to the conveying
direction on the grate. What is new, however, is varying the
addition of air between the primary and secondary combustion air
and varying within different addition points of the secondary air.
It is here especially advantageous for the combustion air ratio (X)
to be held constant during variation.
[0023] The combustion air can be added distributed to the nozzles
and grate, or the distribution of partial volume flows to these
nozzles can be controllably varied.
[0024] During operation of the incinerator, it is especially
advantageous that the combustion air be distributed to the
individual addition points optimized for NO.sub.x, CO and/or
O.sub.2. This means that the distribution of volume flow for
addition to the individual nozzles and/or to the nozzles and the
grate is changed during operation of the incinerator in order to
optimize parameters like NO.sub.x, CO and/or O.sub.2.
[0025] Cumulatively or alternatively, it is provided that the
distribution of combustion air be split among the nozzles in the
flue gas outlet in such a way as to achieve a nearly constant
burnout per unit time. The gas and/or solid burnout can here be
optimized.
[0026] The nozzles make it possible to vary the height of the
burnout plane inside of the flue gas outlet, and in measurements to
analyze the burnout as a function of height in the flue gas outlet,
and as a function thereof to vary the fluid added via the nozzles
in such a way, for example, as to not drop below a specific burnout
level in a specific height of the flue gas outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] An advantageous exemplary embodiment is shown on the
drawing, and will be explained in more detail below. Shown on:
[0028] FIG. 1 is a schematic view of the arrangement of fluid
addition points on a combustion plant, and
[0029] FIG. 2 is a schematic view of a wavy line of flue gases in a
flue gas outlet.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The combustion plant 1 shown on FIG. 1 has a furnace grate 2
and a flue gas outlet 3. The arrows 4 denote the addition of
primary air at the furnace grate 2, and the arrows 5 to 9 denote
the addition of secondary air via nozzles. The nozzles 10 to 14 are
only schematically denoted. The nozzle 10 is here arranged above
the furnace grate 2, and the nozzles 11 and 12 are arranged on a
side 15 of the flue gas outlet 3, while the nozzles 13 and 14 are
arranged on the opposing side 16 of the flue gas outlet 3.
[0031] The dotted lines 17 to 21 denote the primary nozzle
direction of the nozzles 10 to 14.
[0032] With respect to the primary nozzle direction 17, the angle
22 shows the alignment relative to a line 23 connecting the nozzles
12 and 14. The angle 24 shows the alignment of the primary nozzle
direction 17 in relation to the shortest connection 25 of the
nozzle 14 to the opposing side 15 of the flue gas outlet 3.
Finally, the angle 26 shows the primary nozzle direction 17 of the
nozzle 14 in relation to a horizontal plane 27 in the flue gas
outlet 3.
[0033] The two opposing sides 15 and 16 of the flue gas outlet 3
are at an angle 28 to each other, so that the flue gas outlet 3
conically expands in the area between the access 29 to the flue gas
outlet 3 and a transition 30 to perpendicular sides 31 and 32 of
the flue gas outlet 3.
[0034] This results in a lower area 33 of the flue gas outlet 3
between the access 29 from the furnace grate 2 to the flue gas
outlet 3 and the transition 30 from the area 33 of the flue gas
outlet 3 with the inclined sides 15, 16 to the area 34 of the flue
gas outlet with perpendicular walls 31 and 32, which is offset
relative to this second area 34 between the perpendicular walls 31
and 32.
[0035] The nozzle 10 with its primary nozzle direction 21 is
arranged on a wall 35 lying opposite the furnace grate 2, and thus
lies in an area 36 above the furnace grate 2 and before the entry
into the lower area 33.
[0036] During operation of the combustion plant 1, the nozzles 10
to 14 generate a wavy line 37 of flue gas 38, which arises on the
furnace grate 2. Adding secondary combustion air 39 to 43 as the
gas to the flue gas 38 produces the wavy line 37 with its reversal
points 44 to 48. The primary combustion air 49 is supplied to the
combustion plant 1 via the grate 2.
[0037] This makes it possible to add the combustion air in such a
way that the flue gas 38 flows on the wavy line 37. A preferred
method additionally provides that either the secondary combustion
air 39 to 43 or the primary combustion air 49 and the secondary
combustion air 39 to 43 be added distributed among the different
addition points on the grate 2 or on the nozzles 10 to 14 in
varying quantities as a volume flow or mass flow during operation
of the combustion plant. The combustion air ratio can here vary
during operation of the combustion plant. However, it is
advantageous for the combustion air ratio to be held constant.
[0038] Sensors 50, 51 and 52 for NO.sub.x, CO and/or O.sub.2 are
connected with a controller 53, so as to optimize the distribution
of combustion air comprised of primary combustion air 49 and
secondary combustion air 39 to 43 to the individual addition
points.
[0039] The burnout can be determined from the measured values
ascertained with the sensors 50 to 52, making it possible to adjust
the distribution of combustion air to the nozzles so that the
burnout per unit time remains nearly constant.
* * * * *