US3378064A - Tube support - Google Patents

Description

April 16, 1968 I. G. BENKERT 3,378,064

TUBE SUPPORT Filed May 12, 1966 INVENTOR. IRWIN G. BENKERT BY A) ATTORNEY.

United States Patent 3,378,064 TUBE SUPPORT Irwin G. Benkert, Morton, Pa., assignor to Selas Corporation of America, Dresher, Pa., a corporation of Pennsylvania Filed May 12, 1966, Ser. No. 549,526 1 Claim. (Cl. 165-67) ABSTRACT OF THE DISCLOSURE There is provided a liquid cooled tube support for use in a tube heater. The tube support has in it a deflecting member which directs the cooling liquid in an annular path to increase its velocity and cooling effect as it flows through the support. The material being heated in the furnace can be used as the cooling fluid for the support so that this material is preheated.

The present invention relates to tube heating furnaces, and more particularly tube supports and the method of cooling them.

The temperatures to which liquids are being heated in various petrochemical processes, for example, are increasing to the point where it is diflicult to find metals with suificient strength to support the tubes. Various expedients have been tried, such as making the supports hollow and forcing a cooling fluid through them. When this is done with a support large enough to support the coil weight at the temperatures encountered, the required volume of cooling fluid is excessive. In addition the amount of heat removed from the furnace, and lost, is suflicient to have an eflect on the economy of operation.

It is an object of the invention to provide a tube support for a tube heating furnace in which the support is cooled by the fluid being heated. It is a further object of the invention to provide means for strengthening a tube support and for increasing the velocity of the flow of a cooling fluid through it.

The various features of novelty which characterize my invention are pointed out with particularity in the claim annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a section through a furnace in which the tube supports are used,

FIG. 2 is a side view partly in section showing a coil, the supports and the supply of fluid to them,

FIG. 3 is a section through a tube support, and

FIG. 4 is a section taken on line 4-4 of FIG. 3.

Referring to the drawing, there is shown in FIG. 1 a section through a typical tube heating furnace which includes side walls 1 and floor 2. The upper portion of the furnace side walls slant inwardly to a stack 3 through which products of combustion are exhausted. The furnace is supported on structural steel columns 4 at any desired elevation. The furnace is heated by a plurality of horizontal rows of burners 5 in its side walls which burners are shown herein as being of the radiant cup type.

Furnaces of this type are used to heat fluid flowing through a tube which is shown herein as being in the form of a serpentine tube bank or coil 6 made up of a series of horizontal passes 7. The various passes of the tube bank are supported at points along their length by a plurality of tube supports 8, the number depending upon the length of the coil.

Each tube support is formed of an outer tubular mem- 3,378,064 Patented Apr. 16, 1968 ice her 9 made of a metal alloy capable of withstanding temperatures to which the furnace will be heated and of sufficient thickness normally to support the various tube passes. The tubular member is formed at its lower end with a frustro-conical portion 11 which is received in a similarly shaped opening in floor 2 so that the support will be properly located and of the right heighth in the furnace chamber. The upper end of each support can be connected in any suitable manner with a fluid circulating system and is shown herein as being bent at 12 and extending through the upper portion of one of the furnace walls. Each support is provided with a plurality of tube supporting arms 13 which project perpendicularly from the support with the arms extending in diametrically opposite directions and the arms on one side being oflset vertically with respect to the arms on the other side. These arms are provided with passages 14, the ends of which are displaced vertically and which communicate with the interior of the support. A deflector member 15, which may be solid or hollow, is located concentrically within the support in such a manner that its lower end extends below the lowest arm 13 and its upper end extends above the uppermost arm 13. The deflector is located in position in the outer tube 9 by its lower end resting on a spider 16 that is wedged in portion 11. The deflector is provided with a plurality of lugs 17 which bridge the space between the outer surface of the deflector and the inner surface of tubular member to hold the deflector concentric. Ribs 18 project from deflector 15 between the inlet and outlet of each passage 14.

Supports 8 are cooled by a fluid, usually a liquid, which is forced through them in the annular space between the interior of member 9 and the exterior of the deflector member 15. This fluid preferably is the same fluid that is being heated in the serpentine coil 6. To this end there is provided a supply pipe 19 resting on supports 21 beneath the floor 2 of the furnace with the supply pipe being connected to the lower ends of each of the supports. The liquid, when it has reached the top of the supports, goes into a manifold 22 that is connected by a return bend 23 with the inlet end of the tube bank. Generally speaking, manifold 22 will be outside of the furnace and will be protected by a housing 24.

In the operation of the apparatus, burners 5 are ignited to supply heat, both radiant and convection, to the furnace chamber to heat the tubes and the liquid flowing through them. This heat is so intense that under normal circumstances tube supports 8, even if made of a high temperature alloy, do not have the strength to hold the tube coil rigid with the coil passes remaining parallel. The tube supports, however, in this case are cooled by directing the liquid to be heated through the supports. This serves the dual purpose of cooling the supports and preheating the liquid, thereby reducing the size of a normally used convection section (not shown) or increasing the preheating that is obtained. By reducing the volume of the space in the tube supports, the velocity of the flow through them is increased without an abnormally large volume of fluid being required. Increasing the velocity of flow adjacent to the inner surface of member 9 reduces the heat transfer film coeflicient on that surface, thereby increasing heat transfer and lowering the temperature of member 9 with a consequent increase in strength. Because of the great reduction of the skin temperature of deflector 15 compared to the outer member, even when both are cooled, the deflector is quite eflicient as a source of both column and beam strength despite the fact it is of a relatively small diameter.

The increase in beam strength or bending resistance is of importance in maintaining the support straight and vertical as the various passes of the coil slide along arms 13 as they expand and contract due to temperature changes in the furnace.

Thus the expedient of placing a deflector member in a hollow tube support increases the cooling of the support with a reduced flow of cooling fluid, and also adds appreciably to the beam strength of the support.

While in accordance with the provisions of the statutes I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed Without departing from the spirit and scope of the invention set forth in the appended claim, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. Means for supporting a serpentine tube bank adapted to extend horizontally in a furnace chamber having a floor including a tubular support extending vertically upwardly from said floor, arms extending diametrically out from said support at various levels upon which passes of said tube bank are adapted to rest, an elongated deflecting member smaller in diameter than said support received in said support, means to hold said member concentrically in said support with its lower end below the lowest arm and its upper end above the upper arm, means to supply a cooling fluid to said support to flow through the space between said support and said member, the lower end of said support being formed with a constricted substantially frusto-conical portion, means to hold said member in said support including a spider means in said substantially frusto-conical portion, the lower end of said deflector resting on said spider means, and said means to hold said member concentric in said support including a plurality of spaced lugs extending outwardly from said member.

References Cited UNITED STATES PATENTS MEYER PERLIN, Primary Examiner.

ROBERT A. OLEARY, Examiner.

A. W. DAVIS, Assistant Ex'aminer.

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