US3259112A

US3259112A - Removable tube support

Info

Publication number: US3259112A
Application number: US393843A
Authority: US
Inventors: Frank A Lee
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1964-09-02
Filing date: 1964-09-02
Publication date: 1966-07-05
Anticipated expiration: 1983-07-05

Description

- July 5, 1966 F1 A. LEE 3,259,112

REMOVABLE TUBE SUPPORT Filed Sept. 2. 1964 INVENTOR FRANK A. LEE

BY MMM%1JLM ATTORNEY United States Patent Office 3,259,112 Patented July 5, 1966 York Filed Sept. 2, 1964, Ser. No. 393,843 4 Claims. (Cl. 122-510) This invention reates to removable supports for horizontal tubes. In particular, it relates to removable supports for horizontal tubes in a convection section of a fired heater. 7

The present method for supporting horizontal tubes within a fired heater convection section is to vertically mount large stainless steel 2520 chrome nickel or other high strength heat and corrosive resistant tube sheets from the external shell of the fired heater. The sheets are formed with tube size holes which are capable of receiving the tubes therein. The heater tubes are placed through the holes of two or more sheets spaced along the heater for support and alignment.

The tube sheets being in the convection section of the heater are subjected to corrosive attack by vanadium pentoxide, a product of combustion found in fired heaters burning fuel oil. The high operating temperature ranges in fired heaters, 1200" F. and above, also subject the tube sheets to deterioration. Together high temperatures and vanadium pentoxide result in frequent tube sheet failure necessitating replacement of the sheets.

The replacement of defective tube sheets is not a simple task. It entails the removal of all the fired heater tubes passing through the holes in the tube sheets. It requires the opening of the convection section in order to obtain access to the sheets. It requires tedious manipulation in congested convection sections of fired heaters wherein ample working space does not exist. It requires the heater to be shut down during long replacement periods. In total, replacement of tube sheets to date has been an expensive and undesirable operation.

Consequently, it is an object of the present invention to provide a readily removable tube support for horizontal tubes in a convection section of a fired heater.

It is also an object of the present invention to provide a tube support which may be conveniently cooled so as to minimize heat damage.

It is a further object of the present invention to provide a sectionalized tube support that is readily removable solely at sections where deterioration has occurred.

Accordingly, the present invention comprises a heater shell defining a convection section of a fired heater comprising at least one aperture means having opposed openings within the shell through which an elongated hollow open ended rigid support member is disposed. The support member engages horizontal fired heater tubes located in the convection section for supporting the same, and in turn is slidably engaged and supported by the shell aperture means. A locking means is provided for retaining the support member in fixed engagement with the aperture means. Lugs are disposed on the support member which are adapted to position the horizontal tube in alignment. The openings defined by the aperture means are designed to permit longitudinal withdrawal of the support member from outside the heater shell.

The simplicity and ease of removal of the supports provides a great savings in replacement time and labor. Shut down time is kept to a minimum. The tube supports may be replaced while the heater is operational. Replace- 1 on support tubes 13 disposed thereunder.

ment is accomplished without touching the heater tubes and without opening the convection section of the heater. Support sections where deterioration has occurred may be removed at will without the necessity of removing other sections.

These and other advantages of the present invention will become apparent from a detailed description of a preferred embodiment of the invention and drawings, of which:

FIGURE 1 is a longitudinal, vertical section of a fired heater convection section having rows of horizontal tubes and sectionalized supports of the preferred embodiment of the present invention;

FIGURE 2 is a vertical transverse section taken along line 22 of FIG. 1;

FIGURE 3 is a section taken along line 33 of FIG. 2.

Referring now to FIG. 1 for a vertical section of a fired heater convection section, 11 represents the external shell of the convection section. Horizontal heater tube rows 12 carry process fluid. The heater tube rows 12 rest Although not limited thereto, the support tubes 13 are vertically aligned with a support tube underlying each horizontal heater tube row 12. Three vertical arrays of support tubes 13 are shown to support the heater tube rows 12.

FIG. 2 is an enlarged section of FIG. 1 wherein the support tubes 13 are shown mounted from horizontally disposed circular holes 10 in external shell 11. External shell 11 consists of refractory bricks 22, insulation 23, and metal lining24. The support tubes 13 are inserted underneath each horizontal row of tubes 12 for support of the tubes resting thereon.

Support tubes 13 have open-ends 9 and extend beyond the metal lining 24 of the external shell 11. The openended tubes 13 are thereby provided with access for cool ambient air, or external atmosphere, including any suitable surrounding medium for cooling purposes. Air is pulled into the inside 20 of the support tubes 13 as a result of the temperature gradient and circulates naturally therein. In this manner, the temperatures of the support tubes may be maintained below the metal tolerance of the support tubes so as to decrease the rate of temperature attack on the support tubes.

The support tubes 13 are locked in a fixed position by locking pin 15 (shown enlarged in FIG. 3) which is inserted through lock holes '17 and 18, respectively, in cylindrical support sleeves 16 and tube 13. The guide lugs 14 are welded on support tubes 13 in such a position so as to engage heater tubes 12 therebetween when the support tubes 13 are locked by insertion of pin 15. The guide lugs maintain the heater tubes 12 in position and prevent heater tube shifting. I

When a support tube is to be replaced, locking pin 15 is lifted up and removed as shown at 15'. Support tube 13 is then rotated from the outside of the external wall.

11 so that the guide lugs 14 disengage the tubes 12.. A notch opening 21 is provided in external shell 11 and support sleeve 16, aligned with each other so that the guide lugs may slide therethrough when properly aligned with the notch opening. The notch opening is normally packed with insulating cement shown at 25 in FIG. 3 which prevents the fired heater gases from escaping through the notch opening 21 during operation of the heater. How

ever, the insulating cement is easily knocked out by the lugs during replacement of a tube. For replacement, tube 13 is rotated until the guide lugs 14 are horizontally aligned adjacent notch 21 as may be seen from FIG, 3 where rotated guide lug 14' is shown adjacent notch 21. The support tube 13 may then be pulled out from outside of the furnace through the sleeve 16 and external shell 11 and a new support tube 13 inserted.

The heater tubes 12 sag slightly when a support is removed. A smaller diameter tube may be inserted as a wedge to raise the tubes 12 back into position before a new tube support tube 13 is inserted; or, a new support tube 13 may be simultaneously inserted from one end as a deteriorated tube support 13 is being removed from the other end.

Support members other than pipes may be used Without departing from the scope of the present invention. Other modifications and changes in the structure and details of the present invention may be made in accordance with the scope of the present invention as set forth by the appended claims.

What is claimed is:

1. A removable support arrangement comprising:

an external heater shell defining a convection section;

aperture means defining opposed openings through the shell and communicating with the external atmosphere;

horizontal tubes disposed in said convection section;

at least one hollow open ended rigid tube disposed in touching engagement underneath one of the horizontal tubes in the convection section for supporting the horizontal tube;

said rigid tube being slidably engaged and supported by said aperture means and disposed in the opposed openings, the rigid tube being in communication with the external atmosphere;

locking means arranged to retain said rigid tube in fixed engagement with said aperture means; and the aperture means being arranged to permit longitudinal withdrawal of the rigid tube therethrough.

2. A removable support arrangement, comprising an external heater shell defining a convection section;

aperture means defining opposed openings through the shell and communicating with the external atmos phere;

horizontal heater tubes disposed in the convection section;

at least one elongated hollow open ended rigid member disposed in touching engagement underneath one of the horizontal heater tubes in the convection section for supporting the tube;

said member being slidably engaged and supported by said aperture means and disposed in the opposed openings, the rigid member being in communication with the external atmosphere;

locking means arranged to retain said member in fixed engagement with said aperture means;

lugs on said member adapted to position the horizontal heater tube; and

the aperture means being arranged to permit longitudinal withdrawal of the member therethrough.

3. A removable support arrangement, comprising a heater shell defining a convection section, the heater shell comprising an interior refractory side of the shell facing the convection section and an external metal lining side of the shell facing outwards from the heater;

horizontal heater tubes disposed in said convection section defining horizontal rows of parallel heater tubes;

a plurality of aperture means defining opposed openings within the shell, said opposed openings defining a plurality of parallel horizontal aperture lines intersecting the convection section in a direction perpendicular to the heater tubes, said parallel horizontal lines defining a plurality of parallel vertical aperture planes intersecting the convection section in a direction perpendicular to the horizontal heater tubes;

a plurality of vertical arrays comprising a plurality of hollow open ended rigid support tubes forming planes coincident with the aperture planes;

the support tubes being slidably engaged and supported by said aperture means so that the support tubes form lines coincident with the aperture lines, and so that each support tube is horizontally disposed in touching engagement underneath one of the horizontal rows of tubes in the convection section for supporting the row of tubes, each of said array having one support tube for each row of tubes;

the opposed openings defined by said aperture means circular in crosssection and sufiiciently large so that each support tube is rotatably engaged by the aperture means;

a plurality of open-ended cylindrical casing sleeves axially connected to the aperture means extending from the external metal lining side of the shell Wall about the circular opposed openings so that the sleeves protrude outward from the heater;

the support tubes having at least one support tube lock hole near one end of the support tubes;

a plurality of guide lugs disposed in spaced relationship along the surface of each support tube adapted to position the horizontal tubes for engaging in alignment the horizontal heater tubes therebetween;

said aperture means and at least one casing sleeve axially connected thereto defining an aligned notch opening;

said aligned notch opening packed with insulating material so as to close the notch opening from fluid communication with the interior of the convection section;

said aligned notch opening sufiiciently large to permit withdrawal of the guide lugs therethrough when the insulating material is removed;

said notch opening oriented relative the vertical so that the lugs are disengaged from the heater tubes when the lugs are rotated so as to be aligned adjacent the notch opening;

the casing sleeves formed with at least one lock hole in at least one of the sleeves that are connected to each aperture means;

a locking pin for aligned insertion into the casing lock hole in the casing sleeve and in the support tube lock hole in the support tube when said casing lock hole and support tube lock hole are aligned for locking said support tube in fixed position relative the sleeve, said holes being approximately the same in crosssection as the cross-section of the locking pin, the support tube lock hole disposed in the support tube at a position so that when the tube lock hole and the casing lock hole are aligned the guide lugs engage the heater tubes in alignment.

4. A removable support arrangement, comprising a heater shell defining a convection section;

aperture means defining opposed openings within the shell;

horizontal heater tubes disposed in said convection section;

at least one elongated hollow open ended rigid sup.- port tube disposed in touching engagement underneath one of the horizontal heater tubes in the convection section for supporting the tube;

said support tube being slidably engaged and supported by said aperture means;

locking means arranged to retain said support tube in fixed engagement with said aperture means;

lugs on said support tube adapted to position the horizontal heater tube, said lugs being at spaced intervals aligned along the upper surface of the support tube;

the aperture means being arranged to permit longitudinal withdrawal of the support tube therethrough;

the opposed openings defined by said aperture means being circular in cross-section and sufiiciently large so that the support tube is rotatably engaged by the aperture means;

the aperture means defining a notch opening sufficiently large to permit withdrawal of the lugs therethrough 5 and oriented relative the vertical so that the lugs are disengaged from the horizontal heater tubes when aligned with the notch opening.

References Cited by the Examiner UNITED STATES PATENTS 1,883,123 10/1932 Trainer et a1 122-510 X 3,026,858 3/ 1962 Fleischer 1225 10 3,060,909 10/ 1962 Ott 122-510 KENNETH W. SPRAGUE, Primary Examiner.

Claims

1. A REMOVABLE SUPPORT ARRANGEMENT COMPRISING: AN EXTERNAL HEATER SHELL DEFINING A CONVECTION SECTION; APERTURE MEANS DEFINING OPPOSED OPENINGS THROUGH THE SHELL AND COMMUNICATION WITH THE EXTERNAL ATMOSPHERE; HORIZONTAL TUBES DISPOSED IN SAID CONVECTION SECTION; AT LEAST ONE HOLLOW OPEN ENDED RIGID TUBE DISPOSED IN TOUCHING ENGAGEMENT UNDERNEATH ONE OF THE HORIZONTAL TUBES IN THE CONVECTION SECTION FOR SUPPORTING THE HORIZONTAL TUBE; SAID RIGID TUBE BEING SLIDABLY ENGAGED AND SUPPORTED BY SAID APERTURE MEANS AND DISPOSED IN THE OPPOSED OPENINGS, THE RIGID TUBE BEING IN COMMUNICATION WITH THE EXTERNAL ATMOSPHERE; LOCKING MEANS ARRANGED TO RETAIN SAID RIGID TUBE IN FIXED ENGAGEMENT WITH SAID APERTURE MEANS; AND THE APERTURE MEANS BEING ARRANGED TO PERMIT LONGITUDINAL WITHDRAWAL OF THE RIGID THERETHROUGH.