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US 12,044,402 B2Granted
Method for reducing nitrogen oxides in strip heat treatment furnaces
AssigneeAndritz Technology and Asset Management GmbH
InventorsPierre-Jerome Borrel, Eric Blake, Martin Hamman
Life of this patent
Estimating the term…
Abstract
A method for treating a metal strip, where the metal strip undergoes heat treatment in a directly fired furnace and is subsequently heat-treated further in a radiant tube furnace. At least part of the exhaust gases from the radiant tubes is fed to the directly fired furnace.
Claims19
A method for treating a metal strip (5), comprising:
- providing a metal strip (5);
- heat treating the metal strip (5) in a directly fired furnace (1) to yield a directly heated metal strip;
- heat treating the directly heated metal strip in a radiant tube furnace (10), thereby forming exhaust gases (16);
- and
- feeding at least a portion of the exhaust gases (16) from the radiant tubes to at least one burner in the directly fired furnace (1) with the exhaust gases of the radiant tube furnace being mixed with combustion air fed to the at least one burner.
2 more elements
A method for treating a metal strip (5), comprising:
- providing a metal strip (5);
- heat treating the metal strip (5) in a directly fired furnace (1) to yield a directly heated metal strip;
- heat treating the directly heated metal strip in a radiant tube furnace (10), thereby forming exhaust gases (16);
- and
- feeding at least a portion of the exhaust gases (16) from the radiant tubes to at least one burner in the directly fired furnace (1), wherein;
- the directly fired furnace (1) has a non-fired zone (7) arranged before the directly fired zone (2) and an afterburner chamber (9) arranged before the non-fired zone (7) relative to a direction (21) in which the metal strip (5) runs,
- exhaust gases (14) from the directly fired zone (2) flow through the non-fired zone (7) and pre-heat the metal strip (5), and
- the exhaust gases (14) undergo post-combustion in the afterburner chamber (9) after passing through the non-fired zone (7), comprising the step of
- blowing methane into the exhaust gases (14) in the non-fired zone (7), thereby causing at least a portion of any nitrogen oxides present in the exhaust gas (14) to be converted into hydrogen cyanide.
6 more elements
Dependencies are inferred from the claim text.