Furnace with integrated heat recovery utilizing radiative recuperator for preheating combustion reactants using heat from flue gas

Patent metadata

Field	Value
Publication number	US-11280491-B2
Application number	US-201916543049-A
Country	US
Kind code	B2
Filing date	Aug 16, 2019
Priority date	Jun 30, 2017
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A radiative recuperator preheats oxidant and/or fuel for combustion at one or more burners of a furnace. The recuperator includes a duct, at least portions of which comprise a material having a thermal conductivity of greater than 1 W/(m·K), preferably greater than 3 W/(m·K), that receives hot flue gas produced by the burner(s). The duct radiatively transfers heat to oxidant or fuel (for preheating) flowing through one or more metallic pipes disposed in between the duct and an insulating wall.

First claim

What is claimed is:

1. A method of recuperative heat exchange for preheating a combustion reactant with waste heat energy from flue gas produced by a furnace, comprising:
injecting fuel and oxidant from one or more burners mounted in a furnace wall of a furnace into a combustion space within a combustion chamber enclosed by the furnace wall and combusting the injected fuel and oxidant in the combustion space thereby heating solid and/or molten glass or glassmaking materials or solid and/or molten metal and producing flue gas, at least one of the fuel and oxidant being preheated;
receiving the flue gas at a first end of a duct extending along an axis, one or more portions of the duct being comprised of a material having a thermal conductivity of greater than 1 W/(m·K);
discharging the received flue gas from a second end of the duct;
exchanging heat between the flue gas and the duct by radiative heat exchange;
exchanging heat between the duct and one or more metallic pipes by radiative heat exchange across an non-reactive gas space filled with non-reactive gas, the one or more metallic pipes extending through the non-reactive gas space, the non-reactive gas space being defined between an outer surface of the duct and an inner surface of an insulating wall that extends parallel to the duct axis and adjacent the outer surface of the duct;
exchanging heat between the one or more metallic pipes and either fuel or oxidant flowing through the one or more metallic pipes by convective heat exchange to provide preheated fuel or preheated oxidant; and
feeding the preheated fuel or preheated oxidant to the one or more burners), wherein:
each of the one or more metallic pipes is gas-tight;
gaps exist in between, on one hand, the portion or portions with a thermal conductivity of more than 1 W/(m·K), and on the other hand, each of the one or more metallic pipes;
gaps exist between each of the one or more metallic pipes; and
gaps exist between, on one hand, each of the at least one metallic pipes, and on the other hand, the insulating wall.

2. The method of claim 1 , wherein the non-reactive gas is air, the non-reactive gas space freely communicates with ambient air, and no mechanical device is used to create a flow of air through the non-reactive gas space.

3. The method of claim 1 , wherein fuel flows through the one or more pipes and preheated fuel is fed to the one or more burners.

4. The method of claim 1 , wherein oxidant flows through the one or more pipes and preheated oxidant is fed to the one or more burners.

5. The method of claim 4 , wherein the oxidant is oxygen-enriched air, industrially pure oxygen, a mixture of industrially pure oxygen and recirculated flue gas, or a mixture of industrially pure oxygen and carbon dioxide.

6. The method of claim 4 , wherein the oxidant is industrially pure oxygen produced by a cryogenic air separation unit, a vapor swing adsorption unit, or a vaporizer fed with liquid oxygen from a liquid oxygen tank.

7. The method of claim 6 , wherein a totality of all oxidant fed to the one or more burners has an oxygen content of at least 24% by volume.

8. The method of claim 1 , wherein the material having a thermal conductivity of more than 1 W/(m·K) is a ceramic material or metal alloy.

9. The method of claim 1 , wherein the material having a thermal conductivity of more than 1 W/(m·K) is a castable refractory having a SiC content of at least 30%.

10. The method of claim 1 , wherein an entirety of the a duct is comprised of the material having a thermal conductivity of more than 1 W/(m·K).

11. The method of claim 1 , wherein some portions of the duct is comprised of the material having a thermal conductivity of more than 1 W/(m·K) and remaining portions of the duct are comprised of a material having a thermal conductivity of less than or equal to 1 W/(m·K).

12. The method of claim 1 , wherein fuel is flowing through the one or more metallic pipes and preheated fuel is fed to the one or more burners.

13. The method of claim 1 , wherein fuel is flowing through some of the one or more metallic pipes, oxidant is flowing through other of the one or more metallic pipes, and preheated fuel and preheated oxidant are fed to the one or more burners.

14. The method of claim 1 , wherein a temperature of the flue gas is 1,100-1,550° C.

15. The method of claim 1 , wherein the furnace is a glass furnace and the injected fuel and oxidant are combusted in the combustion space thereby heating solid and/or molten glass or glassmaking materials.

16. The method of claim 1 , wherein the furnace is a metal melting furnace and the injected fuel and oxidant are combusted in the combustion space thereby heating solid and/or molten metal.

Assignees

• Air Liquide American
• Air Liquide

Inventors

• Kang Taekyu
• Mcandrew James J F
• Tsiava Remi
• Ma Jiefu
• Adelman Ryan
• Chevrel Henri

Classifications

• F23D99/004

  for use in particular heating operations · CPC title

• F27D17/10

  Arrangements for using waste heat · CPC title

• F28D7/1669

  the conduit assemblies having an annular shape; the conduits being assembled around a central distribution tube · CPC title

• F23D14/66 Primary

  Preheating the combustion air or gas · CPC title

• F23C5/10

  to obtain a flame ring · CPC title