# US 2017/0284656 A1 · High temperature sub-critical boiler with common steam cooled wall between furnace and convection pass

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- Number: US 2017/0284656 A1
- Document ID: US20170284656A1
- Status: Published application
- Kind: A1
- Application number: 15/091,221
- Filed: 2016-04-05
- Published: 2017-10-05
- Earliest claimed: 2016-04-05
- Assignees: The Babcock & Wilcox Company
- Applicants: The Babcock & Wilcox Company
- Inventors: Eric L. Wells; Roger A. Detzel; Albert J. Bennett; Steven D. Thayer
- Web page: https://patentgrep.com/patent/US20170284656A1

## CPC

- F22B 31/04: Heat supply by installation of two or more combustion apparatus, e.g. of separate combustion apparatus for the boiler and the superheater respectively
- F22B 21/34: built-up from water tubes grouped in panel form surrounding the combustion chamber, i.e. radiation boilers
- F22B 37/26: Steam-separating arrangements
- F22G 5/20: by combined controlling procedures
- F22B: METHODS OF STEAM GENERATION; STEAM BOILERS
- F22G: SUPERHEATING OF STEAM

## Abstract

A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. The upper furnace and the convection pass are also located next to each other, so that they share a common steam-cooled wall. There is no open pass between the furnace and the convection pass.

## Claims

### Claim 1

A boiler, comprising:
an upper furnace having steam-cooled membrane walls, the steam-cooled membrane walls comprising pipes sealed by membrane disposed between and connected to the pipes; and
a convection pass downstream of the upper furnace, the convection pass having steam-cooled membrane walls and extending downwards;
wherein the upper furnace and the convection pass share a common steam-cooled membrane wall, the common steam-cooled membrane wall being both a wall of the upper furnace and a wall of the convection pass.

### Claim 2 (depends on 1)

The boiler of claim 1, wherein the common steam-cooled membrane wall is a rear wall of the upper furnace and a front wall of the convection pass.

### Claim 3 (depends on 2)

The boiler of claim 2, wherein the upper furnace includes a side wall, the convection pass includes a side wall having a lower edge, and a seal is present at a junction of the common steam-cooled membrane wall, the upper furnace side wall, and the lower edge of the convection pass side wall.

### Claim 4 (depends on 3)

The boiler of claim 3, further comprising a lower furnace below the upper furnace, the lower furnace having water-cooled membrane walls comprising pipes sealed by membrane disposed between and connected to the pipes.

### Claim 5 (depends on 4)

The boiler of claim 4, further comprising a steam separator configured to deliver dry steam to a steam-cooled circuit including the steam-cooled membrane walls of the upper furnace and configured to receive wet steam from a water-cooled circuit including the water-cooled membrane walls of the lower furnace.

### Claim 6 (depends on 5)

The boiler of claim 5, further comprising one or more superheaters disposed in the upper furnace or the convection pass, the one or more superheaters comprising pipes without membrane.

### Claim 7 (depends on 6)

The boiler of claim 6, further comprising:
a steam separator; and
a steam circuit connected to a dry steam outlet of the steam separator;
wherein the steam circuit includes the common steam-cooled membrane wall shared by the upper furnace and the convection pass.

### Claim 8 (depends on 7)

The boiler of claim 7, further comprising:
burners arranged to combust fuel to generate heated flue gas that flows upward through the upper furnace and then downward through the convection pass;
wherein the common steam-cooled membrane wall is heated by the heated flue gas that flows upward through the upper furnace and by the heated flue gas that flows downward through the convection pass.

### Claim 9

A boiler, comprising:
a furnace having steam-cooled membrane walls forming an upper portion of the furnace, the steam-cooled membrane walls comprising pipes sealed by membrane disposed between and connected to the pipes; and
a convection pass having steam-cooled membrane walls forming at least a portion of the convection pass, and being fluidly connected to the upper portion of the furnace;
wherein the furnace and the convection pass share a common steam-cooled membrane wall comprising a single layer of pipes sealed by a single layer of membrane disposed between and connected to the single layer of pipes.

### Claim 10 (depends on 10)

The boiler of claim 10, wherein the furnace includes:
an upper furnace having the steam-cooled membrane walls and the common stream-cooled membrane wall; and
a lower furnace having water-cooled membrane walls, the water-cooled membrane walls comprising pipes sealed by membrane disposed between and connected to the pipes.

### Claim 11 (depends on 10)

The boiler of claim 10, further comprising a steam separator having a dry steam outlet connected to a steam-cooled circuit including the steam-cooled membrane walls of the upper furnace and a saturated steam inlet connected with a water-cooled circuit including the water-cooled membrane walls of the lower furnace.

### Claim 12 (depends on 11)

The boiler of claim 11, wherein the steam-cooled circuit further includes one or more superheaters disposed in the upper furnace or the convection pass and comprising pipes without membrane.

### Claim 13 (depends on 12)

The boiler of claim 12, further comprising:
burners arranged to combust fuel to generate heated flue gas that flows upward through the upper furnace and then downward through the convection pass;
wherein the common steam-cooled membrane wall is heated by the heated flue gas that flows upward through the upper furnace and by the heated flue gas that flows downward through the convection pass.

### Claim 14

A method of operating a boiler, comprising:
combusting fuel to generate heated flue gas that flows sequentially upwards through an upper furnace and downwards through a convection pass; and
sending superheated steam through a common steam-cooled membrane wall to capture heat energy from the heated flue gas and further superheat the superheated steam;
wherein the common steam-cooled membrane wall is heated both by the heated flue gas flowing upward through the upper furnace and by the heated flue gas flowing downward through the convection pass.

### Claim 15 (depends on 14)

The method of claim 14, wherein the superheated steam sent through the common steam-cooled membrane wall is generated from water that is heated in a lower furnace to obtain wet steam that is subsequently separated in a steam separator to obtain water and dry steam.

### Claim 16 (depends on 15)

The method of claim 15, wherein the dry steam passes through at least one superheater prior to being sent to the common steam-cooled membrane wall.

### Claim 17 (depends on 16)

The method of claim 16, wherein the common steam-cooled membrane wall comprises a single layer of pipes separated by membrane therebetween.

### Claim 18 (depends on 17)

The method of claim 17, wherein the upper furnace includes a side wall, the convection pass includes a side wall having a lower edge, and a seal is present at a junction of the common steam-cooled membrane wall, the upper furnace side wall, and the lower edge of the convection pass side wall.