Method for heating a blast furnace stove

Patent metadata

Field	Value
Publication number	US-9896735-B2
Application number	US-201013510108-A
Country	US
Kind code	B2
Filing date	Nov 25, 2010
Priority date	Nov 26, 2009
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A method for heating a blast furnace stove includes combusting a fuel with a lower heating value (LHV) of 9 MJ/Nm 3 or less in a combustion zone which is arranged in a combustion chamber in the stove, and causing the combustion gases to flow through and thereby heat refractory material in the stove. The fuel is combusted with an oxidant including at least 85% oxygen, and combustion gases are recirculated into the combustion zone for diluting the mixture of fuel and oxidant therein sufficiently for the combustion to be flameless.

First claim

What is claimed is:

1. A method for heating a blast furnace stove including a combustion chamber having a combustion zone therein, comprising:
combusting a fuel with a lower heating value (LHV) of not more than 9 MJ/Nm 3 in the combustion zone of the blast furnace stove,
causing combustion gases to flow through and be exhausted from refractory material in the stove for heating said refractory material,
supplying and adding an oxidant comprising an oxygen content of at least 85% into the combustion chamber for recirculating the combustion gases including said oxidant into the combustion zone, wherein the recirculating the combustion gases is from a location inside the combustion chamber, but outside an area of the combustion chamber occupied by the combustion zone,
further supplying the oxidant to the combustion zone at high velocity through at least one lance, thereby entraining the combustion gases into the combustion zone for diluting of the mixture,
diluting a mixture of the fuel and the oxidant with the recirculated combustion gases, and
flamelessly combusting said mixture in the combustion zone.

2. The method according to claim 1 , wherein the supplying the oxidant through the at least one lance is at a velocity of at least 200 m/s.

3. The method according to claim 2 , wherein the supplying the oxidant through the at least one lance is at least at sonic velocity.

4. The method according to claim 3 , further comprising arranging an orifice of the at least one lance adjacent to a supply inlet for the fuel for entraining said fuel into the combustion zone by ejector action.

5. The method according to claim 4 , further comprising providing additional oxidant to the combustion chamber downstream of the supply inlet for the fuel for achieving staged combustion in the combustion zone.

6. The method according to claim 1 , further comprising supplementing an existing air burner for the stove with at least one high-velocity oxidant lance for injecting said oxidant.

7. The method according to claim 1 , further comprising recycling combustion gases flowing through the refractory material back into the combustion zone.

8. The method according to claim 7 , further comprising premixing the recycled combustion gases with said oxidant before entering the combustion zone.

9. The method according to claim 7 , wherein a sufficient amount of the combustion gases are recycled when total oxygen percentage by volume of an inert portion of an atmosphere in the combustion chamber, excluding non-inert fuel components, does not exceed 12%.

10. The method according to claim 7 , further comprising replacing an existing air burner in the stove with a fuel inlet and an inlet for recycled combustion gases, and combusting the fuel with said oxidant.

11. A method according to claim 10 , wherein a sufficient amount of the combustion gases are recycled to maintain a gas mass flow per time unit through the refractory material at a level which is at least the same as a gas mass flow per time unit used when operating the existing air burner without recycling.

12. The method according to claim 10 , wherein a sufficient amount of the combustion gases are recycled to maintain a flame temperature at a level which is not more than, and a thermal energy transfer to the refractory material at a level which is not less than, the flame temperature and the thermal energy throughput per time unit, respectively, which was used when the existing air burner was operating without recycling.

13. The method according to claim 1 , wherein the fuel comprises blast furnace top gas.

14. The method according to claim 13 , further comprising obtaining the blast furnace top gas from a blast furnace supplied with hot air from the stove.

Assignees

• Cameron Andrew
• Ekman Tomas
• Gartz Mats
• Linde Ag

Inventors

• Cameron Andrew
• Ekman Tomas
• Gartz Mats

Classifications

• C21B9/10 Primary

  Other details, e.g. blast mains · CPC title

• C21B9/00 Primary

  Stoves for heating the blast in blast furnaces · CPC title

• C21B2100/20

  Increasing the gas reduction potential of recycled exhaust gases · CPC title

• Y02P10/122

  by capturing or storing CO2 · CPC title

• C21B2100/60

  Process control or energy utilisation in the manufacture of iron or steel · CPC title