Industrial furnace and method of utilizing heat therefrom

Patent metadata

Field	Value
Publication number	US-11029090-B2
Application number	US-201816131552-A
Country	US
Kind code	B2
Filing date	Sep 14, 2018
Priority date	Mar 24, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A continuous industrial furnace comprising: an inlet; a heating zone; a cooling zone; and an outlet in this order, the continuous industrial furnace being configured to heat-treat a workpiece while conveying the workpiece from the inlet to the outlet, wherein at least a part of the heating zone comprises a furnace wall heat insulation structure, the furnace wall heat insulation structure comprising: an outer wall having one or more gas introducing ports; and a porous thermal insulation layer arranged with a gap on an inner side of the outer wall; and wherein the heating zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the heating zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer In this order and then flows toward the inlet side.

First claim

What is claimed is:

1. A continuous industrial furnace comprising: an inlet; a heating zone; a cooling zone; and an outlet in this order, the continuous industrial furnace being configured to heat-treat a workpiece while conveying the workpiece from the inlet to the outlet,
wherein at least a part of the cooling zone comprises a furnace wall heat insulation structure, the furnace wall heat insulation structure comprising: an outer wall having one or more gas introducing ports; and a porous thermal insulation layer having a lower surface, at least one side surface, and an upper surface, and defining a gap between the upper surface thereof and an inner side of the outer wall;
wherein the at least one side surface of the porous thermal insulation layer contacts at least a portion of an outer surface of the cooling zone;
wherein an inflowing gas in the gap defines a gas layer covering the upper surface of the porous thermal insulation layer; and
wherein the cooling zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the cooling zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer in this order and then is utilized for cooling the workpiece.

2. The continuous industrial furnace according to claim 1 , wherein the gas discharged from the exhaust ports has a temperature of from 100 to 600° C.

3. A method of utilizing heat of the continuous industrial furnace according to claim 1 , the method comprising:
supplying gas from the gas introducing ports, the gas sequentially passing through the gap and the porous thermal insulation layer and then flowing into the cooling zone of the furnace, wherein heat is exchanged between the gas and the porous thermal insulation layer while the gas passes through the porous thermal insulation layer, whereby heat release from the porous thermal insulation layer to an outside of the furnace is reduced and a temperature of a surface of the porous thermal insulation layer on the furnace inner side is decreased;
cooling the workpiece by convective heat transfer due to the gas flowing into the furnace and by radiant heat transfer to an inner surface of the furnace wall, and increasing a temperature of the gas flowing into the furnace by heat exchange between the gas and the workpiece while allowing the gas to flow through the furnace;
sucking and discharging the gas after utilizing the gas flowing into the furnace to cool the workpiece; and
utilizing sensible heat of the sucked and discharged gas outside the furnace.

4. A continuous industrial furnace comprising: an inlet; a heating zone, a cooling zone; and an outlet in this order, the continuous industrial furnace being configured to heat-treat a workpiece while conveying the workpiece from the inlet to the outlet,
wherein at least a part of the heating zone comprises a furnace wall heat insulation structure, the furnace wall heat insulation structure comprising: an outer wall having one or more gas introducing ports; and a porous thermal insulation layer having a lower surface and an upper surface, and defining a gap between the upper surface thereof and an inner side of the outer wall;
wherein the heating zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the heating zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer in this order and then flows toward the inlet side;
wherein at least a part of the cooling zone comprises the furnace wall heat insulation structure;
wherein the lower surface of the porous thermal insulation layer contacts an outer surface of the heating zone continuously along a length thereof;
wherein the at least one side surface of the porous thermal insulation layer contacts at least a portion of an outer surface of the cooling zone;
wherein an inflowing gas in the gap defines a gas layer covering the upper surface of the porous thermal insulation layer; and
wherein the cooling zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the cooling zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer in this order and then is utilized for cooling the workpiece.

5. The continuous industrial furnace according to claim 4 , wherein the gas discharged from each exhaust port of the heating zone and the cooling zone has a temperature of from 100 to 600° C.

6. The continuous industrial furnace according to claim 4 , wherein the furnace comprises a portion where an internal temperature of the furnace in the heating zone into which the gas flows through the porous thermal insulation layer is 1000° C. or more.

7. The continuous industrial furnace according to claim 4 , wherein the gas flowing into the heating zone of the furnace comprises a furnace atmosphere adjusting gas.

8. A method of utilizing heat of the continuous industrial furnace according to claim 4 , the method comprising:
supplying gas from the gas introducing ports of the heating zone, the gas sequentially passing through the gap and the porous thermal insulation layer at the heating zone and then flowing into the heating zone of the furnace, wherein heat is exchanged between the gas and the porous thermal insulation layer at the heating zone while the gas passes through the porous thermal insulation layer at the heating zone, whereby a temperature of the gas is increased and heat release from the porous thermal insulation layer at the heating zone to an outside of the furnace is reduced;
allowing the gas flowing into the heating zone of the furnace to flow toward the inlet side, wherein heat is exchanged between the gas and the workpiece while the gas flows through the furnace toward the inlet side, whereby the temperature of the gas is decreased and a temperature of the workpiece is increased;
sucking and discharging the gas after allowing the gas flowing into the heating zone of the furnace to flow toward the inlet side; and
utilizing sensible heat of the gas sucked and discharged from the heating zone outside the furnace;
supplying gas from the gas introducing ports of the cooling zone, the gas sequentially passing through the gap and the porous thermal insulation layer at the cooling zone and then flowing into the cooling zone of the furnace, wherein heat is exchanged between the gas and the porous thermal insulation layer at the cooling zone while the gas passes through the porous thermal insulation layer at the cooling zone, whereby heat release from the porous thermal insulation layer at the cooling zone to an outside of the furnace is reduced and a temperature of a surface of the porous thermal insulation layer on the furnace inner side at the cooling zone is decreased;
cooling the workpiece by convective heat transfer due to the gas flowing into the cooling zone of the furnace and by radiant heat transfer to an inner surface of the furnace wall, and increasing a temperature of the gas flowing into the cooling zone of the furnace by heat exchange between the gas and the workpiece while allowing the gas to flow through the furnace;
sucking and discharging the gas after utilizing the gas flowing into the cooling zone of the furnace to cool the workpiece; and
utilizing sensible heat of the gas sucked and discharged from the cooling zone outside the furnace.

9. The method according to claim 8 , wherein the gas is discharged outside the furnace after the gas flows into the furnace through the porous thermal insulation layer at a position where an internal temperature of the furnace in the heating zone is 400° C. or more and an average of 40% or more

Assignees

• Ngk Insulators Ltd

Inventors

• Hanzawa Shigeru
• Yasue Takashi

Classifications

• F27D17/10

  Arrangements for using waste heat · CPC title

• F27B9/243

  Endless-strand conveyor · CPC title

• F27D7/02

  Supplying steam, vapour, gases or liquids · CPC title

• F27D17/00

  Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases · CPC title

• F27B9/36

  Arrangements of heating devices · CPC title