US3844254A

US3844254A - Furnace having walls defined by tube membranes

Info

Publication number: US3844254A
Application number: US00366115A
Authority: US
Inventors: I Astrom
Original assignee: Goetaverken Angteknik AB
Current assignee: Goetaverken Angteknik AB
Priority date: 1972-06-19
Filing date: 1973-06-01
Publication date: 1974-10-29
Anticipated expiration: 1991-10-29
Also published as: SE364104B; FI54023C; FR2190251A5; JPS571748B2; JPS4956467A; GB1428418A; DE2328943A1; CA988370A; FI54023B

Abstract

The furnace of a waste liquor recovery furnace is often defined by water tube membranes. The chemical residue formed as a result of the combustion is likely to react forcibly when mixed with water, and every caution should be taken in the design to avoid the risk of tube leaks. The corner connection between two wall membranes is difficult to arrange, and if a strong combustion puff should occur the weld seams at the corner tube may cause a leak from which water could gush into the molten residues causing an explosion. To avoid this risk the corner tubes are free from the adjacent membranes, but are retained thereto by means of special clamping means.

Description

United States Patent [191 Astrom Oct. 29, 1974 [5 FURNACE HAVING WALLS DEFINED BY 2,368,265 1/1945 Shellenberger 122/6 A TUBE MEMBRANES 3,404,663 10/1968 Lewis et al 122/367 R Inventor: Ingmar Astrom, Stenungsund,

Sweden Gotaverkens Angtekniska AB (Gotaverken Heat Engineering Co., Ltd.), Goteborg, Sweden Filed: June 1, 1973 Appl. No.: 366,115

Assignee:

Foreign Application Priority Data June 19, 1972 Sweden 8035/72 U.S. Cl. 122/6 A, 122/235 A Int. Cl. F22b 37/00 Field of Search 122/6 A, 235 A, 7; 110/98 References Cited UNITED STATES PATENTS 8/1934 Toomey 122/6 A 12/1935 Selaya 122/6 A Primary Examiner-Kenneth W. Sprague Assistant Examiner-Larry l. Schwartz Attorney, Agent, or FirmPierce, Scheffler & Parker [5 7 ABSTRACT The furnace of a waste liquor recovery furnace is often defined by water tube membranes. The chemical residue formed as a result of the combustion is likely to react forcibly when mixed with water, and every caution should be taken in the design to avoid the risk of tube leaks.

The corner connection between two wall membranes is difficult to arrange, and if a strong combustion puff should occur the weld seams at the comer tube may cause a leak from which water could gush into the molten residues causing an explosion.

To avoid this risk the corner tubes are free from the adjacent membranes, but are retained thereto by means of special clamping means.

1 Claim, 1 Drawing Figure FURNACE HAVING WALLS DEFINED BY TUBE MEMBRANES BACKGROUND OF THE INVENTION The furnaces of many combustion plants nowadays often have walls consisting of tube membranes, i.e., spaced water tubes interconnected by means of fins or similar members welded together to form a flat unit. The tubes of these membranes are often covered by some protecting cladding, which may consist of a fire resistant compound stamped onto the wall, or of blocks of fire and corrosion resistant material in any suitable manner attached to the wall.

With certain types of furnaces the risk of explosions or forceful puffs of combustion gases is imminent. So is for instance the case with different types of refuse and waste combustion furnaces, especially furnaces for the combustion of waste liquor from the cellulose pulp manufacture. During the combustion of such liquor a chemical residue is formed at the bottom of the hearth, and if water from a cracked tube comes into contact with this residue a forceful explosion will occur, which will deform the walls and may result in more tubes being cracked.

SUMMARY OF THE INVENTION Furnaces of this type are often designed with a quadrilateral cross section, and the damages are most likely to occur near the corners of the furnace. The membranes are fitted at an angle to the tube forming the corner, and if the walls, following an explosion, are bent outwards the attachments at the corner tube will be heavily stressed, which easily will lead to a cracking of some tube, or tubes. According to the invention the furnace is therefore designed in such a manner, that a tube located at each corner of the furnace is free from the adjacent membranes and is connected to the latter by means of clamps arranged externally of the walls and adapted for securing the blocks to the walls, said clamp at the pertaining corner tube extending to each direction therefrom at least over the outermost tube in the adjacent membrane.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows by way of example a corner portion of a furnace belonging to a waste liquor combustion plant.

DESCRIPTION OF THE PREFERRED EMBODIMENT The walls of the furnace are composed of a number of water tubes 10, which within each side wall of the furnace are welded together to membranes. The faces of the tubes turned towards the furnace are covered by blocks 11 of fire resistant material, which are forced towards the tubes by means of wedge shaped members 12. These are retained at the wall by means of clamps I3 and bolts 14.

According to the invention two membranes arranged at an angle to each other and meeting each other at a corner are not interconnected directly by welding, but are locked together by means of a separate tube 15, which forms part of the water circulation system, but is not welded to either of the membranes. Tube 15 is, however, connected to the adjacent membranes by means of the clamps 13 used for retaining the wedge shaped members 12 at the corner portion. These clamps are designed in such a manner that they from the corner tube extend over at least one, preferably over two tubes in the adjacent membrane.

It is evident that the walls of big furnaces may each contain more than one membrane, so a single unit does not extend from one corner tube to the other. It is further evident that the shape of the blocks and of the wedge members, as well as of the clamps is not limited to the examples shown in the drawing, but will have to be suited to the actual application. The essential part is that the corner tubes are free from the membranes, and that the clamps at the corners have sufficient length to provide the required strength.

What I claim is:

I. In a steam boiler furnace having parallel water tubes interconnected by welding to form tube membranes, said membranes being assembled to define a combustion chamber having quadrilateral cross section and being provided, at their faces turned towards the combustion chamber, with blocks of fire-resistant material secured by clamping means located outside the wall,

the improvement of a water tube located at each corner of the combustion chamber, said tube lacking permanent connection of the adjacent tube membranes;

block retaining clamping means extending over the pertaining corner tube and at least the outermost tube in each of the adjacent tube membranes thereby locking said corner tube to said adjacent membranes; and

web-shaped blocks of fire-resistant material secured by said block-retaining clamping means to the faces of said corner tubes turned toward said chamber.

Claims

1. In a steam boiler furnace having parallel water tubes interconnected by welding to form tube membranes, said membranes being assembled to define a combustion chamber having quadrilateral cross section and being provided, at their faces turned towards the combustion chamber, with blocks of fireresistant material secured by clamping means located outside the wall, the improvement of a water tube located at each corner of the combustion chamber, said tube lacking permanent connection of the adjacent tube membranes; block retaining clamping means extending over the pertaining corner tube and at least the outermost tube in each of the adjacent tube membranes thereby locking said corner tube to said adjacent membranes; and web-shaped blocks of fire-resistant material secured by said block-retaining clamping means to the faces of said corner tubes turned toward said chamber.