U.S. patent application number 14/063286 was filed with the patent office on 2014-05-01 for arrangement of a flue gas treatment system and a combustion device.
This patent application is currently assigned to ALSTOM Technology Ltd. The applicant listed for this patent is ALSTOM Technology Ltd. Invention is credited to Jean-Marc Gilbert AMANN, Erik W. BOOS, Jorgen Per-Olof GRUBBSTROM, Lars NILSSON, Wuyin WANG.
Application Number | 20140120002 14/063286 |
Document ID | / |
Family ID | 47088725 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140120002 |
Kind Code |
A1 |
NILSSON; Lars ; et
al. |
May 1, 2014 |
ARRANGEMENT OF A FLUE GAS TREATMENT SYSTEM AND A COMBUSTION
DEVICE
Abstract
An arrangement of a flue gas treatment system and a combustion
device includes a recirculation line to supply at least a part of
the flue gas from the combustion device back to the combustion
device, a selective catalytic reduction unit (SCR), a gas
processing unit (GPU) to separate CO.sub.2 from the flue gas. The
recirculation line departs upstream of the selective catalytic
reduction unit (SCR), and the selective catalytic reduction unit
(SCR) is upstream of the gas processing unit (GPU).
Inventors: |
NILSSON; Lars; (Rottne,
SE) ; AMANN; Jean-Marc Gilbert; (Vaxjo, SE) ;
BOOS; Erik W.; (Vederslov, SE) ; GRUBBSTROM; Jorgen
Per-Olof; (Vaxjo, SE) ; WANG; Wuyin; (Vaxjo,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALSTOM Technology Ltd |
Baden |
|
CH |
|
|
Assignee: |
ALSTOM Technology Ltd
Baden
CH
|
Family ID: |
47088725 |
Appl. No.: |
14/063286 |
Filed: |
October 25, 2013 |
Current U.S.
Class: |
422/169 |
Current CPC
Class: |
B01D 2257/104 20130101;
B01D 2251/2067 20130101; B01D 2251/2062 20130101; B01D 2258/0283
20130101; F23C 99/00 20130101; B01D 2257/404 20130101; B01D 53/26
20130101; B01D 53/48 20130101; B01D 2251/102 20130101; B01D 53/565
20130101; B01D 2255/207 20130101; B01D 53/8625 20130101; B01D
2255/1021 20130101; B01D 2255/1023 20130101; B01D 2257/30 20130101;
B01D 2257/502 20130101; B01D 53/864 20130101; B01D 2256/22
20130101; B01D 53/75 20130101; Y02C 20/40 20200801; Y02C 10/04
20130101; F01N 3/2066 20130101 |
Class at
Publication: |
422/169 |
International
Class: |
F01N 3/20 20060101
F01N003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2012 |
EP |
12190213.4 |
Jun 18, 2013 |
EP |
13172576.4 |
Jun 18, 2013 |
EP |
13172579.8 |
Aug 19, 2013 |
EP |
13180815.6 |
Claims
1. An arrangement of a flue gas treatment system and a combustion
device, the flue gas treatment system comprising a recirculation
line to supply at least a part of the flue gas from the combustion
device back to the combustion device, a selective catalytic
reduction unit (SCR), wherein the flue gas treatment system
comprises a gas processing unit (GPU) to separate CO.sub.2 from the
flue gas, the recirculation line departs upstream of the selective
catalytic reduction unit (SCR), and the selective catalytic
reduction unit (SCR) is upstream of the gas processing unit
(GPU).
2. The arrangement according to claim 1, further comprising a heat
exchanger for cooling the flue gas upstream of the selective
catalytic reduction unit (SCR).
3. The arrangement according to claim 2, wherein the heat exchanger
is a preheater for an oxidiser to be supplied to the combustion
device.
4. The arrangement according to claim 1, further comprising a dust
removal unit upstream of the selective catalytic reduction unit
(SCR).
5. The arrangement according to claim 4, wherein the temperature of
the flue gas at the outlet of the dust removal unit fits the
temperature needed at the selective catalytic reduction unit
(SCR).
6. The arrangement according to claim 1, further comprising a heat
exchanger immediately downstream of the selective catalytic
reduction unit (SCR).
7. The arrangement according to claim 1, wherein the gas processing
unit (GPU) comprises at least a compressor step and a cooling
step.
8. The arrangement according to claim 1, wherein at the selective
catalytic reduction unit (SCR) a reducing agent is injected into
the flue gas.
9. The arrangement according to claim 8, wherein the injection of
the reducing agent occurs upstream of the selective catalytic
reduction unit (SCR).
10. The arrangement according to claim 1, wherein the selective
catalytic reduction unit (SCR) operates at a substantially
atmospheric pressure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to the following European
applications: European application 12190213.4 filed Oct. 26, 2012,
European application 13172579.8 filed Jun. 18, 2013, European
application 13172576.4 filed Jun. 18, 2013 and European application
13180815.6 filed Aug. 19, 2013, the contents of which are each
hereby incorporated in their entireties.
TECHNICAL FIELD
[0002] The present disclosure relates to an arrangement of a flue
gas treatment system and a combustion device. The boiler is
preferably an oxyfired boiler, i.e. a boiler in which a fuel is
combusted using pure or almost pure oxygen as an oxidizing
agent.
BACKGROUND
[0003] It is known to provide flue gas treatment systems downstream
of boilers.
[0004] FIG. 1 shows an example of a known flue gas treatment system
1 connected to a combustion device 2 such as a boiler.
[0005] FIG. 1 shows that the flue gas treatment system 1 has a
selective catalytic reduction unit SCR located immediately
downstream of the combustion device 2; at the selective catalytic
reduction unit SCR NO.sub.x is converted into N.sub.2 and H.sub.2O.
Downstream of the selective catalytic reduction unit SCR a
pre-heater 4 is provided, to pre-heat the air to be provided to the
boiler (namely to the combustion chamber of the boiler). Thus an
electrostatic precipitator ESP for removal of particles and a wet
flue gas desulphurization WFGD are provided. From the wet flue gas
desulphurization WFGD the flue gas is sent to the stack.
[0006] The known flue gas treatment system has some drawbacks.
[0007] In fact, since all flue gas has to pass through the
selective catalytic reduction unit SCR, the selective catalytic
reduction unit SCR must have a large size (i.e. large enough for
the whole flue gas).
SUMMARY
[0008] An aspect of the disclosure includes providing an
arrangement of a flue gas treatment system and a combustion device
by which the selective catalytic reduction unit SCR has a smaller
dimension than what needed for known flue gas treatment
systems.
[0009] This also favourably influences the costs that are
reduced.
[0010] These and further aspects are attained by providing an
arrangement of a flue gas treatment system and a combustion device
in accordance with the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Further characteristics and advantages will be more apparent
from the description of a preferred but non-exclusive embodiment of
the arrangement of the flue gas treatment system and a combustion
device, illustrated by way of non-limiting example in the
accompanying drawings, in which:
[0012] FIG. 1 is a schematic view of a flue gas treatment system
according to the prior art;
[0013] FIG. 2 is a schematic view of a flue gas treatment system in
an embodiment of the invention.
DETAILED DESCRIPTION
[0014] With reference to FIG. 2, this shows an arrangement of a
flue gas treatment system 1 and a combustion device 2 such as a
boiler. The boiler is preferably an oxyfiring boiler, i.e. a boiler
having a combustion chamber that is supplied with a fuel (such as
coal, oil, gas) and substantially pure oxygen (purity preferably
greater that 95%). The main component of the flue gas generated in
the oxyfired boiler is CO.sub.2.
[0015] The flue gas treatment system 1 comprises a recirculation
line 10 to supply at least a part of the flue gas generated at the
combustion device 2 back to the combustion device 2. For example
2/3 of the whole flue gas generated at the combustion device 2 are
recirculated via the recirculation line 10 and the remaining 1/3 of
the flue gas is further treated.
[0016] Downstream the recirculation line 10, a selective catalytic
reduction unit SCR is provided. The selective catalytic reduction
unit SCR operates at a substantially atmospheric pressure.
[0017] For example, the selective catalytic reduction unit SCR is
defined by a bed or a structure of catalyst material through which
the gas passes through. Upstream the selective catalytic reduction
unit SCR a reducing agent like ammonia or urea is injected into the
flue gas. In the selective catalytic reduction unit SCR unit the
ammonia or the urea then reacts with the NO.sub.x present in the
flue gas to form N.sub.2 and H.sub.2O.
[0018] The flue gas from the selective catalytic reduction unit SCR
is preferably supplied into a heat exchanger 14 to recover heat,
and then into a desulphurization unit such as a wet flue gas
desulphurization WFGD defined by a absorption column (or a scrubber
column, or a scrubber tower), in which typically scrubber liquid is
sprayed from the top counter currently to the gas entering at the
bottom of the column.
[0019] Downstream of the wet flue gas desulphurization WFGD a gas
processing unit GPU is provided to separate CO.sub.2 from the other
gas of the flue gas.
[0020] The gas processing unit GPU separates a stream 16 of
substantially pure CO.sub.2 from a stream 18 of the remaining
components of the flue gas that are mainly defined by Argon,
N.sub.2 and are usually vented.
[0021] The gas processing unit GPU for example comprises a
compression step and a cooling step.
[0022] Advantageously, the recirculation line 10 departs upstream
of the selective catalytic reduction unit SCR, and the selective
catalytic reduction unit SCR is upstream of the gas processing unit
GPU and operates at a substantially atmospheric pressure. Upstream
and downstream are to be intended with reference to the flow of
flue gas.
[0023] Between the combustion device 2 and the diverting 19 of the
recirculation line 10, a heat exchanger 20 is preferably provided.
Therefore the heat exchanger 20 is in the loop of the recirculation
line 10. The heat exchanger 20 cools the flue gas upstream of the
selective catalytic reduction unit SCR.
[0024] The heat exchanger 20 is preferably a preheater for an
oxidiser such as oxygen to be supplied to the combustion
device.
[0025] In addition, a dust removal unit 22 upstream of the
selective catalytic reduction unit SCR can also be provided.
[0026] Advantageously the temperature of the flue gas at the outlet
of the dust removal unit 22 fits the temperature needed at the
selective catalytic reduction unit SCR. This is anyhow not
mandatory and an additional heat exchanger (cooler or heater) can
be provided to fit the temperature needed at the selective
catalytic reduction unit SCR.
[0027] The operation of the arrangement is apparent from that
described and illustrated and is substantially the following.
[0028] At the combustion device 2 a fuel is combusted with oxygen
generating steam (that is for example expanded in a steam turbine)
and flue gas.
[0029] The flue gas is directed through the preheater 20 where it
is cooled (at the same time oxygen directed into the combustion
chamber of the combustion device is heated). The cooled flue gas
passes then through the dust removal unit 22 (such as an
electrostatic precipitator or a filter) where dust and solid
particles are removed from it.
[0030] The flue gas treated this way is split in a first part
(about 2/3 of the total flue gas generated at the combustion device
2) that is recirculated back into the combustion chamber of the
combustion device and a second part (about 1/3 of the total flue
gas generated at the combustion device) that is supplied to the
selective catalytic reduction unit SCR.
[0031] Since the amount of flue gas supplied to the selective
catalytic reduction unit SCR is only a fraction of the total flue
gas generated at the combustion device, the selective catalytic
reduction unit SCR can have a size substantially smaller that the
selective catalytic reduction unit size needed for traditional flue
gas treatment systems.
[0032] At the selective catalytic reduction unit SCR a reducing
agent like for example ammonia or urea is injected into the flue
gas, such that NO.sub.x is converted into N.sub.2 and H.sub.2O.
Typically the injection of the reducing agent occurs upstream of
the selective catalytic reduction unit SCR. At the heat exchanger
14 and wet flue gas desulphurization H.sub.2O and SO.sub.2 are
respectively removed from the flue gas that is thus ready to enter
the gas processing unit GPU.
[0033] At the gas processing unit GPU the flue gas is compressed
and cooled to separate the CO.sub.2 from the other components of
the flue gas generating the stream 16 and 18.
[0034] Naturally the features described may be independently
provided from one another.
[0035] In practice the materials used and the dimensions can be
chosen at will according to requirements and to the state of the
art.
* * * * *