Combustion process

Patent metadata

Field	Value
Publication number	US-2023194082-A1
Application number	US-202218080429-A
Country	US
Kind code	A1
Filing date	Dec 13, 2022
Priority date	Dec 21, 2021
Publication date	Jun 22, 2023
Grant date	—

Abstract

Combined combustion and post-combustion method whereby flue gas is generated by combustion in a main combustion zone, the flue gas being evacuated from the main combustion zone and introduced into a post-combustion zone where the flue gas is subjected to post-combustion and post-combusted gas is obtained which is evacuated from the post-combustion zone, whereby a first level of one or more combustible substances in the flue gas evacuated from the main combustion zone and/or a second level of one or more combustible substances in the post-combusted gas evacuated from the post-combustion zone is/are monitored, whereby a control signal is generated on the basis of the monitored level(s) and whereby the post-combustion oxidant injection rate or the stoichiometric excess of post-combustion-oxidant with respect to post-combustion fuel is regulated in function of said control signal.

First claim

What is claimed is:

1 . A combined combustion and post-combustion method comprising:
a) defining a nominal post-combustion operation mode for a post-combustion zone with either:
(1) a nominal post-combustion-oxidant injection rate into the post-combustion zone, when the post-combustion zone is an oxidant-only post-combustion zone which is not equipped for the injection of post-combustion fuel therein, or
(2) a nominal post-combustion-oxidant injection rate and a nominal post-combustion-fuel injection rate into the post-combustion zone, when the post-combustion zone is an oxidant-fuel post-combustion zone which is equipped for the injection of both post-combustion oxidant and post-combustion fuel therein, the nominal post-combustion-oxidant injection rate and the nominal post-combustion-fuel injection rate defining a nominal stoichiometric excess of the post-combustion oxidant with respect to the post-combustion fuel,
b) supplying fuel and combustion oxidant to a main combustion zone at respectively an actual fuel supply rate and an actual oxidant supply rate, c) combusting the supplied fuel with the supplied oxidant in the main combustion zone, thus producing heat and flue gas, which may contain residual combustible matter, d) evacuating the flue gas from the main combustion zone and introducing the evacuated flue gas into the post-combustion zone, e) injecting, into the post-combustion zone:
(1) post-combustion oxidant at an actual post-combustion-oxidant injection rate and no post-combustion fuel, when the post-combustion zone is an oxidant-only post-combustion zone, or
(2) post-combustion oxidant at an actual post-combustion-oxidant injection rate and post-combustion fuel at an actual post-combustion-fuel injection rate, when the post-combustion zone is an oxidant-fuel post-combustion zone, the actual post-combustion-oxidant injection rate and the actual post-combustion-fuel injection rate defining an actual stoichiometric excess of post-combustion oxidant with respect to the post-combustion fuel,
f) post-combusting the evacuated flue gas in the post-combustion zone with:
(1) the post-combustion oxidant in the case of an oxidant-only post-combustion zone, or
(2) the actual stoichiometric excess of post-combustion oxidant in the case of an oxidant-fuel post-combustion zone,

thereby generating a post-combusted gas,
g) evacuating the post-corn busted gas from the post-combustion zone,
h) monitoring a first level of one or more combustible substances in the flue gas evacuated from the main combustion zone and/or a second level of one or more combustible substances in the post-combusted gas evacuated from the post-combustion zone,
i) generating a first control signal on the basis of the level or on the basis of one or both of the levels monitored in step h), and
j) regulating, in function of the first control signal:
(1) the actual post-combustion-oxidant injection rate in the case of an oxidant-only post-combustion zone, or
(2) the actual stoichiometric excess of post-combustion-oxidant through the actual post-combustion-oxidant injection rate and/or the actual post-combustion-fuel injection rate, in the case of an oxidant-fuel post-combustion zone.

2 . The method according to claim 1 , whereby the first control signal is generated on the basis of the second monitored level.

3 . The method according to claim 2 , whereby step a) comprises:
i. defining an upper threshold B 1 up for the second monitored level, and whereby, when the second monitored level exceeds the upper threshold B 1 up, the generated first control signal causes, in step j)
(1) the actual post-combustion-oxidant flow to be higher than the nominal post-combustion-oxidant flow, in the case of an oxidant-only post-combustion zone, or
(2) the actual stoichiometric excess of post-combustion-oxidant to be greater than the nominal stoichiometric excess of post-combustion-oxidant, in the case of an oxidant-fuel post-combustion zone.

4 . The method according to claim 2 , whereby step a) further comprises:
1 ′. defining a lower threshold B 1 low for the second monitored level, and/or ii′. defining a lower threshold B 2 low for the second monitored level and a corresponding time period ΔtB,
whereby, when the second monitored level is below threshold B 1 low or remains below lower threshold B 2 low during at least time period ΔtB, the generated first control signal causes in step j):
(1) the actual post-combustion oxidant flow to equal to the nominal post-combustion-oxidant flow, in the case of an oxidant-only post-combustion zone or
(2) the actual post-combustion oxidant flow and the actual post-combustion fuel flow to be equal to respectively the nominal post-combustion oxidant flow and the nominal post-combustion fuel flow in the case of an oxidant-fuel post-combustion zone.

5 . The method according to claim 1 , whereby the first control signal is generated on the basis of the first monitored level.

6 . The method according to claim 5 , whereby step a) further comprises:
i. defining an upper threshold C 1 up for the first monitored level, and whereby, when the first monitored level exceeds the upper threshold C 1 up the generated first control signal causes, in step j)
(1) the actual post-combustion-oxidant flow to be higher than the nominal post-combustion-oxidant flow, in the case of an oxidant-only post-combustion zone, or
(2) the actual stoichiometric excess of post-combustion-oxidant to be greater than the nominal stoichiometric excess of post-combustion-oxidant, in the case of an oxidant-fuel post-combustion zone.

7 . The method according to claim 5 , whereby step a) comprises:
i. defining a lower threshold C 1 low for the first monitored level, and/or ii. defining a lower threshold C 2 low for the first monitored level and a corresponding time period ΔtC,
whereby, when the first monitored level is below threshold C 1 low or remains below lower threshold C 2 low during at least time period ΔtC, the generated first control signal causes in step j):
(1) the actual post-combustion oxidant flow to equal to the nominal post-combustion-oxidant flow, in the case of an oxidant-only post-combustion zone, or
(2) the actual post-combustion oxidant flow and the actual post-combustion fuel flow to be equal to respectively the nominal post-combustion oxidant flow and the nominal post-combustion fuel flow, in the case of an oxidant-fuel post-combustion zone.

8 . The method according to claim 1 , whereby the first control signal is generated on the basis of both the first and the second monitored level.

9 . The method according to claim 8 , whereby step a) comprises:
i. defining an upper threshold C 1 ′up for the first monitored level, and ii. defining an upper threshold B 1 ′up for the second monitored level, and whereby when the first monitored level exceeds upper threshold C 1 ′up or when the second monitored level exceeds upper threshold B 1 ′up, the generated first control signal causes, in step j)
(1) the actual post-combustion-oxidant flow to be higher than the nominal post-combustion-oxidant flow in the case of an oxidant-only post-combustion zone or
(2) the actual stoichiometric excess of post-combustion-oxidant to be greater than the nominal stoichiometric excess of post-combustion-oxidant, in the case of an oxidant-fuel post-combustion zone.

10 . The method according to claim 9 , whereby step a) comprises:
i. defining a lower threshold C 1 ′low for the first monitored level and a lower threshold B 1 ′ low for the second monitored level, and/or ii. defining a lower threshold C 2 ′low for the first monitored level and a corresponding time period ΔtC′ and a low

Assignees

• Air Liquide

Inventors

• Paubel Xavier
• Ba Abou
• Rheker Frank
• Kepinski Laurent
• Amirat Mohan
• Senechal Jean-Baptiste

Classifications

• F23N5/18

  using detectors sensitive to rate of flow of air or fuel · CPC title

• F23G7/06 Primary

  of waste gases or noxious gases, e.g. exhaust gases (exhaust apparatus for engines with means for rendering the exhaust innocuous, e.g. by thermal or catalytic conversion, F01N3/08; combustion of uncombusted material from primary combustion within apparatus for combustion of solid or fluent fuel F23B {, of non combusted material from primary combustion of solid fuels; of gases produced by primary combustion of solid fuels F23B90/04}, F23C) · CPC title

• F27D2019/0031

  through control of the flow of the exhaust gases · CPC title

• F23L7/007

  Supplying oxygen or oxygen-enriched air · CPC title

• F23N1/022 Primary

  using electronic means · CPC title