Method for carrying out combustion in an industrial furnace

Patent metadata

Field	Value
Publication number	US-9689614-B2
Application number	US-201113228827-A
Country	US
Kind code	B2
Filing date	Sep 9, 2011
Priority date	Sep 30, 2010
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A method for combustion in an industrial furnace having fuel and a first oxidizer to heat a material includes arranging at least one lance in a sidewall of the furnace; supplying a second oxidizer with an oxygen content of at least 85 percent by weight in the form of a jet traveling at at least sonic velocity to the interior of the furnace through the at least one lance; running the jet of the second oxidizer in the horizontal plane above the material between and essentially in parallel with two consecutive rows of the roof burners; balancing an amount of the second oxidizer supplied per time unit so that the oxygen content supplied via the second oxidizer constitutes at least 50 percent by weight of the total supplied oxygen per time unit in the furnace.

First claim

The invention claimed is:

1. A method for combustion in an industrial furnace, the interior of which is caused to be heated by a matrix of downwards directed roof burners arranged in at least two rows in the roof of the industrial furnace, wherein the roof burners are driven with a fuel and a first oxidizer to heat a material in the interior of the furnace, comprising:
providing the matrix of downwards directed roof burners in the roof;
arranging at least one oxidizer lance in a sidewall of the furnace;
supplying a second oxidizer with an oxygen content of at least 85 percent by weight in the form of a jet traveling at at least sonic velocity to the interior of the furnace through the at least one oxidizer lance;
running the jet of the second oxidizer in a horizontal plane above the material between and essentially parallel with two consecutive rows of the roof burners; and
balancing an amount of the second oxidizer supplied per time unit so that the oxygen content supplied via the second oxidizer constitutes at least 50 percent by weight of total supplied oxygen per time unit in the furnace.

2. The method according to claim 1 , wherein supplying the second oxidizer is at a velocity of at least Mach 1.5.

3. The method according to claim 1 , wherein that the second oxidizer comprises an oxygen content of at least 95 percent by weight.

4. The method according to claim 1 , wherein the balancing the amount of the second oxidizer supplied per time unit, comprises balancing the amount of the second oxidizer so that the oxygen content supplied via the second oxidizer constitutes at least 70 percent by weight of the total supplied oxygen per time unit in the furnace.

5. The method according to claim 1 , wherein the first oxidizer comprises air.

6. The method according to claim 5 , wherein the roof burners comprise air cooled air burners, and further comprising controlling air flow through the roof burners to the lowest possible level at which adequate cooling of the roof burners is possible, and controlling an amount of the second oxidizer supplied so that a desired global stoichiometric equilibrium is achieved in the furnace.

7. The method according to claim 1 , wherein the matrix of roof burners comprises at least three rows of the roof burners and at least four roof burners in each of the rows.

8. The method according to claim 1 , wherein the at least one oxidizer lance opens out at a height along the sidewall between an upper surface of the material and an inner roof of the furnace at a vertical distance from a highest point of the upper surface of the material of between 50% and 60% of the smallest vertical distance between the material and the inner roof of the furnace.

9. The method according to claim 1 , wherein the furnace is at least 8 meters wide in a direction parallel to the rows of the roof burners, and comprising arranging a respective lance for the second oxidizer to supply the second oxidizer at said at least sonic velocity from a respective orifice arranged at either side of the furnace opposite each other so that respective jets of the second oxidizer are parallel but directed in opposite directions towards each other.

10. The method according to claim 1 , wherein the matrix of roof burners comprises at least three rows, the furnace is not greater than 10 meters wide in a direction parallel to the rows of the roof burners and wherein the at least one oxidizer lance comprises a plurality of oxidizer lances, and further comprising arranging the plurality of oxidizer lances for the second oxidizer to supply the second oxidizer at said at least sonic velocity from respective orifices arranged on either side of the furnace, and supplying respective jets of the second oxidizer in opposite directions towards each other along rows of the roof burners in different respective spaces between said rows for providing a closed loop circulation of the second oxidizer in the respective spaces.

11. The method according to claim 1 , wherein a spread angle for the jet of the second oxidizer is not greater than 10°.

12. A method for increasing efficiency and temperature homogeneity, as well as decreasing an amount of formed NO x and CO 2 in an industrial furnace having a matrix of air driven roof burners, comprising:
downwardly directing the air driven roof burners toward a material in the furnace;
supplementing the furnace with at least one oxidizer lance for a second oxidizer to be provided to the furnace;
arranging the at least one oxidizer lance in a sidewall of the furnace;
supplying the second oxidizer with an oxygen content of at least 85 percent by weight in the form of a jet traveling at at least sonic velocity to the interior of the furnace through the at least one oxidizer lance;
running the jet of the second oxidizer in a horizontal plane above the material in the furnace between and essentially parallel with two consecutive rows of the roof burners; and
balancing an amount of the second oxidizer supplied per time unit so that the oxygen content supplied via the second oxidizer constitutes at least 50 percent by weight of the total supplied oxygen per time unit in the furnace.

13. The method according to claim 12 , comprising balancing an amount of supplied fuel per time unit through the roof burners to a total supplied oxygen per time unit during operation and when needed, wherein maximum heating power is caused to increase for the furnace.

Assignees

• Lugnet Anders
• Ekman Tomas
• Linde Ag

Inventors

• Lugnet Anders
• Ekman Tomas

Classifications

• F23L9/00

  Passages or apertures for delivering secondary air for completing combustion of fuel  (baffles or deflectors in air inlets F23M9/02) · CPC title

• F27B9/3011 Primary

  arrangements for circulating gases transversally · CPC title

• C03B5/2353

  by combustion with pure oxygen or oxygen-enriched air, e.g. using oxy-fuel burners or oxygen lances · CPC title

• F23C5/08

  Disposition of burners · CPC title

• F23L7/007

  Supplying oxygen or oxygen-enriched air · CPC title