US2415068A - Tube spacer and support - Google Patents

Description

Feb. 4, 1947. J, ANDREW, JR v 2,415,068

TUBE SPACER AND SUPPORT Filed July 13, 1945 2 Sheets-Sheet 1 amlmwlwu T ig. 3

' INVENTOR. James DAndreugJr:

BY v

VA ITORNE Y L Feb. 4, 1947.

J. D. ANDREW. JR

TUBE SPACER AND SUPPORT Filed July 15. 1943 2 Sheets-Sheet 2 r as r 132 f 90 I06 I;

' I28 Ho Fig. 5

A mwshron James D. Andrew, J1."

y i n A TI'ORNE Y atented Feb 1947 UNITED STATES PATENT OFFlCE Tuna sracna Am) surron'r James D. Andrew, In, Essex Fells, N. 3., asslgnor to The Babcock & Wilcox Company, Rock- Ieigh, N. 1., a corporation of New Jersey Application July 1a, 1943, Serial No. 494,5

The invention herein disclosed relates to a tube spacer construction for maintaining the tubes of a bank of tubes in predetermined spaced relation transversely of their lengths. The invention is applicable to the fluid carrying tubes 13 Claims. (cl. 122'4'i8) In accordance with this invention it is also an object t'outilize a. material or materials sufliciently resistant to 'the temperatures to be encountered as 'to afford a construction relatively permanent in character.

of heat exchangers generally but is especially' advantageous when applied to the tubes of a heat exchanger wherein relatively long'lengths of tubes are arrangedupright and are swept by' heating gases of relatively high temperatures.

It is known that in convection heated apparatus of the character herein described the spacing of the tubes transversely of their lengths has an important bearing on the rate of heat transferand, with other conditions remaining constant, a closer spacing of the tubes results in a higher rate of heat transfer. When tube spacings are 'made small, any variation in the spacing between individual tubes of the bank alters the area available for gas flow between tubes, and because of the normally close spacing the change in gas flow area is a high percentage of the intended area, and the resulting gas mass flow becomes appreciably higher or lower depending on the' direction of change.

Such displacements of the tubes may result from overheatingof the tube metal causing distortion due to the high temperatures of the heating gases in relation to temperatures of the fluid withinthe tubes. Since the tubes of An additional object is to provide a spacer support capable of being manufactured and installed simultaneously, thereby contributing to savings in labor and expense, and by forming an essentially monolithic structure enabling a predetermined, spacing of the tubes to be maintained.

The foregoing objects and advantages, as well as others will be more fully understood from the description to follow, particularly when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a sectional side elevation of a boiler unit illustrating an embodiment of my invention as applied to the superheater thereof;

Fig. 2 is a sectional plan of the boiler unit shown in Fig. 1,- taken along line 2-4;

themselves are unable to resist this tendency to become distorted, it has been customaryto employ spacer elements ofone description or another in an attempt to maintain the spacings at their intended normal values, but such means as heretofore used have been inadequate in that they do not provide a sufficiently rigid lateral support to the tubes in every direction, nor do they afford an especially durable separator means capable of withstanding the high temperatures of the heating gases over reasonably long periods before requiring replacement.

Spacer elements for the tubes of superheaters, for example, have usually been made of metal, andbecause of the high temperatures involved, such elements have been formed of various alloys whose compositions for the most part Fig. 3 is a fragmentary enlargement of parts shown in Fig, 1;

Fig. 4 is a plan view, partly broken away, of partsshown in Fig. 3; Fig. 5 is a sectional. side elevation of a boiler unit showing an application of my invention in modified form, and

Fig. 6 is an enlarged fragmentary plan section of partsshown in Fig. 5.

In detail and referring particularly to Figs. 1 and 2, the boiler unit as shown is of the integral-furnace type wherein the boiler furnace or combustion chamber i0 is located to one side of the boiler heating surface comprising groups of upright boiler tubes i2, i4 and I6 which are connected to the upper and lower boiler drums require metals'which are not only. expensive, but

18 and 20. The disposition of boiler heating surface in relation to the boiler furnace is generally similar to the arrangement disclosed in U. S. Patent to E. G. Bailey et a1. 1,999,984, granted April 30, 1935. The furnace is suitably fired from one end as indicated in Fig. 2, utilizing burners 22 'of atype selected for the character of fuel or fuels to be burned.

The hot gases of combustion are discharged from the furnace chamber through the gas outlet provided between one end of the inclined deflector bailie 26-and the adjacent wall 28 of the setting, thegases being directed over the groups of boiler tubes l2, l4 and it through a plurality of transverse heating gas passes 30, 32 and 34 arranged in a horizontal series adiacentthe side wall ,36 of the setting, such-passes.being principallydei'lned by :the transverse bailie walls 38 and 40, and the longitudinal baflle wall 42, in combination with adjacent walls of the setting. The

spent heatingga'ses leave the setting through the gas outlet conveniently located at the bottom of the final gas pass 34.

In their course through the first gas pass 30 the hot gases of combustion are directed over the tubes of a superheater 46 wherein the superheater tubes 48 are formed as U-shaped loops and are arranged upright with the closed ends of the loops uppermost. A section transversely of the superheater tube bank, as illustrated in Fig. 2, shows the tube lengths as being arranged in bundles and being spaced apart in successive rows extending transversely of the direction of gas flow and, in addition, in successive rows paralleling the direction of gas flow. The superheater tubes have their ends connected to bottom headers 58, 52 and 54, one group of tubes connecting the inlet header 58 with an intermediate header 52, and the remaining group of tubes connecting the intermediate header 52 with, the outlet header 54, thereby causing steam to pass through the two groups of superheater tubes in succession. The inlet and outlet headers 50 and 54 may be made separate, or may be formed as separate sections of the same header, the saturated steam being conducted to the inlet header or section 50 through connections 56 leading-from the upper steam and water drum [8. The headers er level intermediate the intended thickness of 50, 52, 54 are cradled in longitudinally spaced cantilever beams 58 which are fixed to the lower boiler drum 20 thereby supporting the superheater entirely from below. tory 60 above the headers serves as a protection for the superheater tube connections and the header supports 58.

The preferred means for maintaining the superheater tubes 48 in a predetermined spaced 'relation is essentially monolithic and formed as A layer of refracthe finished plate as shown. Some or all of the wires may be welded to certain tubesof the bank as indicated at 88 as a means of resisting any tendency for the completed spacer to shift along the tubes.

It is desirable to make certain that the tubes 48 are properly spaced and in alignment before placing the material 64 within the form, and preferably to provide some temporary spacer means (not shown) designed to remain in place until the material 64 has fully hardened. The material 64 in its initially fluid or plastic state is poured or rammed into the form or mold which has been provided, to completely fill the spaces between and around the tubes 48 and, being somewhat cementitious in character, will upon hardening form a solid substantially monolithic and self-sustaining structure capable of maintaining its shape under all service conditions, the

hardened materialconforming closely to the contours of the tubes, and adhering to a degree to their surfaces, to preserve the intended tube the application of heat and retains its hardness I and strength up to its limiting temperature of 2600 F., in addition to having low expansion and shrinkage values and providing adequate resistment. Each plate 62 for each leg of the tube bank is preferablydi vided at 68 into separate sections 62a and 62b thus providing a separate section for each leg for each pass of the steam through the superheater, a section 62a being provided for each leg of tubes conducting steam at a-relatively low temperature from the saturated steam inlet header 58 to. the intermediate header 52, and a section 62b being provided for each le of tubes conducting steam at a higher temperature from intermediate header 52 .to the superheated steam outlet header 54.

The installation of the tube spacer 62 is facilitated by constructing a temporary form about the tubes 48 at the desired location, as indicated by dotted lines in Fig. 3. *Such a form. of wood for example, may consist of a pair of beam members 18 extending across the direction of gas flow,

boards 16 and "completing the temporary structure.

The wires, or rods 66 may then be placed between thetubes at the desired intervals, either and variation in spacings of the tubes.

ance to abrasion.

In View of the inclination of the tubes '48, the tendency for the tube bank to rotate about its lower support 58 is opposed by angles 82 secured as by U-bolts 84 to adjacent boiler tubes 86.

It has been found that a single plate 62 for each leg of'the superheater tube bank.46 is adequate for maintaining tube spacing and alignment where 'previously a plurality of metallic spacers had been required. The monolithic type of spacer provides a substantially permanently rigid assembly whereas with the metallic spacers formerly employed, a multiplicity of parts was required, involving numerous separate assemblies, and resulting in an overall assembly of the bank which was subject to distortion of its shape in service and consequent misalignment Moreover, the monolithic type of spacer 62 is in itself ,highly refractory to the hot combustion gases independent of any cooling effect due to its thermal engagement with the tube walls. In the case of metallic spacers, the original thermal contact with the tubes is generally incomplete and ordinarily cannot be maintained, so that regardless of the metal employed, whether cast iron or a temperature resistant alloy,; the spacers are apt to be burned away with a, resulting variation in tube spacings and an impairment in the rate of heat transfer.

In the modification according to Figs. 5 and 6, the boiler unit is of a type wherein the major portion of the boiler heating surface comprises banks of tubes 88 and 90 connected to upper and lower boiler drums 92 and 94 and laterally adjoining a boiler furnace or combustion chamber 06 fired by burners 08 suitable for the fuel or fuels to be burned.

A superheater I is positioned between the banks of boiler tubes 88 and '90, being screened in part from the radiant heat of the combustion .chamber by the bank of boiler tubes 90. Saturated steam is conducted from the upper boiler drum 92 by means of tubes I02 to. the inlet superheater header I04 from which it passes through vertically extending tubes I06 of a first section of the superheater to an intermediate header I08; thence through connections IIO to a desuperheater unit (not shown) within the lower drum 94; thence through connections Hz to an intermediate header H4; and then through vertically extending tubes II6 of asecond superheatersection to the superheater outlet header H8.

The hot gases of combustion leaving the'fur nace chamber 96 sweep across the entire exposed lengths of boiler tubes 90 and immediately thereafter engage the banks of superheater tubes H6 and I00 in succession, whereupon the flow of gases is continued throughout'the boiler bank 88 in a plurality of longitudinal passes H9, I20 and ma to the gas outlet I24.

A monolithic form of spacer plate I 26 is employed for each of the banks or bundles of superheater tubes I06 and IIS, similar in construction and material to the spacer means 62, and

for this reason such details need not be repeated.

- viating the use of the usualoverhead metallic suspensionmembers which because of the temperature zone in which located would require the use of heat resistant alloys difficult to obtain,

the weight of the superheater being carried by a plurality of suitably supported transverse beams I20 on which rest the-superheater headers I04, I108, ill and H8.

The tubes I06 andIIIi of both superheaterv sections are in multiple loop formation, so that each tube I06 or I I6 provides a plurality of passes across the flow of heating gases. Asseen in Fig. 6, the spacing of, tubes I06 in rows extending longitudinally of the upper drum I8 is one-half the spacing of the superheater tubes H6, and of the boiler screen tubes 90, in similarly arranged rows. All of the superheater tubes H6 may therefore be'extended upwardly to a level where their upper loop ends are between the horizontally extending .portions I30 of the boiler screen tubes 90 which thus serve to prevent excessive relative movement laterally between the tubes H0 at their ends. Due to the closer spacing of tubes I06 in the other section of the superheater, only half of these, could be conveniently extended upwardly into thespaces between the horizontal boiler tube portions I30, and consequently, in preference, a monolithic bafile structure I32 is provided adjacent the'roof of the set-. ting, and the upper loop ends of tubes I 06' extended into the lower wall thereof, desirably through individual openings therein, whereby excessive relative movement of such tube ends is similarly prevented. The guiding of tubes I06 and H0 at their upper loop ends, as described, permits expansion and contraction of the bottom-supported tube lengths with minimum distortion, and in conjunction with the rigid monolithic spacer I26 at an intermediate location, enables longentube loops to be used than if the upper loop ends were left entirely free and unrestricted as to relative lateral movement. For example, but without indicating specific limitations of the invention, in the form of Fig. 1 where the upper loop ends are left free, the height of the loops above the layer of refractory B0 is approximately one hundred three times the diameter of the tubes, whereas in the form of Fi .5 where the .upper tube ends are guided, the height of the loops above the floor I34 of the setting may be approximately one hundredtwenty-nine times the diameter of the tubes, the increase in ratio, 'ofloop length to tube diameter thus being approximately twenty-five per cent.

The invention as herein disclosed in accordance 25. with the provisions of the statutes will be understood by persons skilled in the art to be applicable in arrangements other than those specifically described, and to include features which may be used to advantage without a corresponding use of other features, within the scope of the appended claims.

I claim:

1. In combination with a bundle of closely spaced superheater tubes arranged upright for transverse flow of heating gases thereover in a single gas flow heating pass, said tubes being arranged in rows paralleling said heating gas flow With several of said tubes in each of said .rows, a

header at thelower ends of said tubes to which 40 said tubes are connected for sustaining the weight of said tubes and for maintaining the lowermost extremities of individual tubes in spaced relation transversely of said bundle,

means for maintaining said .tubes in predetermined spaced relation throughout other portions of their lengths comprising a slab of hardened plastic heat resistant material installed between and around said tubes transversely of said. bundle at a location intermediate the height of said bundle, and means associated with said slab and cooperating solely with said tubes for maintaining said spacer slab substantially fixed in position longitudinally of said tubes.

2. In combination with serially connected bundles of superheater tubes adapted to be contacted successively by heating gases flowing transversely thereover, the tube lengths throughout each bundle being arranged upright and being spaced apart both in the direction .of gas flow and in a direction transversely thereto, said tube lengths being arranged in rowsparalleling said heating gas flow with several of said tube lengths in each of said rows, means for supporting the weight of said tubes'entirely from below, and

plate-like members predominantly monolithic and non-metallic each extending across the tube lengths of one of said bundles for separately supporting the tube lengths of each bundle laterally to maintain predetermined spacings between tube 7 lengths in said bundles, each said spacing and supporting member engaging only the tube lengths of one. of said bundles and being sustained solely thereby. i

3. In combination with a bank of inverted U- shaped superheater tubes having the major pormeans for supporting said headers and thereby the entire weight of said superheater tubes, and monolithic means disposed transversely of at least said bundle first contacted by said gases for rigidly supporting the tube lengths of said bundle against lateral displacement, whereby the spacing between the tube lengths of said bundle is maintained constant, said monolithic spacer lengths of said bundle and having its weight supported wholly thereby, said bundle comprising tube lengths arranged in a plurality of rows paralleling the flow of said gases with a'plurality of tube lengths disposed in each of said rows.

4. In combination with a bankof inverted U- shaped superheater tubes having the major portions of their lengths. straight and forming serially connected spaced bundles of tube lengths adapted to'be contacted successively by heating gases flowing transversely thereof, each bundle comprising tube lengths arranged in a'plurality of rows paralleling the flow of. said gases with a plurality oi tube lengths disposed in each or said rows, headers to ,which the lower ends of said tubes are connected, means for supporting said headers and thereby the entire weight of said superheated tubes, and monolithic members each disposed transversely of one of said bundles for rigidly, supporting the tube lengths of each bundle separately against lateral displacement, whereby the spacing between tube lengths in a given bundle is maintained constant without interferlngwith the movement of one bundle relative to another, each said monolithic spacer and supportingmember for each bundle having its weight supported wholly by the bundle of tubes engaged thereby.

5. In combination, a bank of upwardly extending superheater tubes adapted to be swept by heating gases flowing transversely thereover to a and supporting means engaging only the tube nected by loops at theiruppere'nds and arifg for transverse flow of high temperature heating gases thereover, the straight length portions in each of said groups being'arranged in rows paralleling said heating gas flow with several of said portions in each of said rows, means forsupporting the weight of said tube bank entirely from below, and means for rigidly supporting said tubes laterally at a location intermediate their heights to maintain constant relative spacings between the straight length portions in a selected group, said last named means comprising a predominantly monolithic and nonmetallic plate-like member extending transversely of the tube portions of' said group and being wholly supportedthereby, said member engaging only the tube portions in said group and being in close fitting relation to all said tube portions in said group.

7. In a'superheater having tubes arranged in bundles forming successive portions of the flow path for the fluid being heated, each bundle comprising straight length tube portions arranged upright in transverse relation to the flow of high temperature heating gases thereover in a single gas flow heating pass, said straight length portions being disposed in closely spaced rows paralleling the direction of heating gas flow with a plurality of said portions in closely spaced relation in each of said rows, means for supporting the weight of at least one of said bundles of superheater tubes entirely from one end including stationary header means to which the corresponding ends of the tubes of said bundle are connected and the tubes thereby held in fixed lateral relation only at said end of support, and means for maintaining other portions of the tubes of said end supported bundle in predetermined spaced relation in all directions laterally throughout said bundle comprising a substantially monolithic and gas outlet adjacent the upper portion of said bank, said tubes including vertically extending straight lengthportions connected at their ends by return bendsto form a.succession of continuous tube lengths in looped formation each paralleling the direction of heating gas flow, headers below the level of said bank to which the ends of sa-idlooped tube lengths are connected, means a for supporting said headers'and thereby the entire weight of said superheater tubes, a rigid plate-like structure arranged transversely of said straight tube length portions at a level intermediate the height of said bank for maintaining the spacing of said tube length portions constant, said structure being predominantly monolithic and beingsustained solely by tub lengths enga'ged thereby, said structure being disposed at a level below said gas outlet and arranged to deflect a portion of said heating gases downwardly to offset the tendency for some of said gases to bypass the lower portions of said'superheater non-metallic heat resistant plate-like member extending transversely of the straight length tube portions at a location intermediate the heightof said single heating gas pass, said members embracing substantially all straight length tube portions in all of saidrows in closely fitting relation to the walls'thereof, said member embracing only the tubes of a single bundle and havin its I weight supported wholly thereby.

8. In a superheater having tubes arranged in serially connected bundles for successive flow of high temperature heating gases thereover in a single transverse pass, each bundle comprising straight length tube portionsiarranged upright and disposed in closely spaced relation in rows paralleling the direction of heating gas flow with a plurality of said portions in closely spaced relation in each of said rows, means for supp rting the weight of said superheater tubes entirely from one end including stationary header means to which said tubes are connected and thereby held in fixed lateral relation only at said end of support, said header means including an inlet, an intermediate, and an outlet header section, said tubes being connected to said sections to provide a progressive fluid flow path from 'said inlet to said outlet section in aplurality of passes relative to vthe flow of said heating gases, one of said bundleshavlng all of its tubes connected to said intermediate header section, a second bundle comprising a first group oi tubes connected to said inlet header section and a second group of tubes connected to said outlet header section, and a, heat resistant plate-like member predominantly monolithic disposed transversely of the tubes of at least said second bundle at a lofitting relation to the tube walls, said member embracing only the tubes of a single bundle, the member for said second bundle being divided into separate relativelymovable portionsfor said first and second groups of tubes.

9. In combination, a heat exchanger formed of tube lengths arranged uprightv in separate bundles and connected to provide a progressive flow path for the fluidbeing heated, said bundles being arranged in succession relative-to the flow of high temperature heating gases thereover in a single transverse pass, said tube lengths being disposed in a plurality of closely spaced rows paralleling the direction of heating gas flow with at'least several of said lengths in closely spaced relation in each of said rows, means for fixin the positions of said tube lengths at one'end only of each bundle thereby leaving other portions of said tube lengths toward the opposite end of each bundle free to move in response to temperatur variations, refractory plate-like members of substan tially monolithic formation each arranged transversely of the tube lengths of one of said bundles and forming a separate rigid support and spacer means for the tube lengths of said bundle in all directions laterally throughout said bundle, each said member being disposed at a level intermediate the height of said tube lengths in said single heating gas pass and being sustained solely by the tube lengths engaged thereby.

10. In combination with a bundle of closely spaced superheater tube lengths arranged upright for transverse flow of heating gases thereover in a single gas flow heating pass, said tube lengths being arranged in rows paralleling said heating gas flow with several of said lengths in eachof said rows, means for sustaining the weight of said bundle from one end only and for maintaining the extremities of individual tube lengths at said end in spaced relation transversely of said bundle, a slab of plastic heat resistant material hardened in place between and around said tube lengths transversely of said bundle ata location intermediate the height of said bundle, and means secured to tube lengths embraced by said slab for maintaining said slab in a predetermined position longitudinally of said bundle, said slab constituting the sole means other than said first named means for maintaining said tube lengths in predetermined spaced relation throughout their lengths.

11. In combination with a bank 01' inverted U- shaped superheater tubes having the major portions of their lengths straight and taming serially connected bundles of tube lengths .adapted to be contactedsuccessively by heating gases flowing transversely thereover, each bundle comprising tube lengths arrangedin a plurality of rows paralleling the flow of said gases with a plurality of said tube lengths disposed in each of said rows, headers to which the lower ends of said tubes are connected including inlet and outlet headers between which steam entering said inlet headeris caused to flow through said tubes to said outlet header in a plurality of passes relative to the flow of said heating gases, means for supporting said headers and thereby the entire weight of said superheater tubes, and separateplate-like means disposed transversely of the tube lengths of each of said bundles for maintaining the spacing between said tube lengths constant without interfering with the movement of one bundle relative to another, said tube spacing means for any one of said bundles being divided into relatively movable sections at a location corresponding-to the division between a plurality of said steam flow passes, each of said. sections being predominantly monolithic and being supported wholly by the tube' lengths with which it is associated.

* 12. In combination with a bundle of closely spaced superheater tube lengths arranged upright for transverse flow of heating gases thereover in a single gas flow heating pass, said tube lengths being arranged in rows paralleling said heating gas flow with several of said lengths in each of said rows, means for sustaining the weight of said bundle from one endpnly and for, maintainin the extremities of individual tube lengths at said end in spaced relation transversely of said bundle, and a slab of plastic heat resistant material hardened in plac between and around said tube lengths transversely ofsaid bundle at a location intermediate the height of 'said bundle, said slab being supported solely by the tubelengths engaged thereby and constituting I the sole means other than said first named means for maintaining said tub lengths in predetermined laterally spaced relation.

13. In a heat exchanger having fluid conducting tubes arranged in serially connected bundles for successive flow of high temperature heating gases thereover in a single transverse pass, each bundle comprising substantially straight tube lengths arranged upright and disposed in closely, spaced relation in rows paralleling'the direction of heating gas flow with a plurality of said tube lengths in closely spaced relation in each of said rows, means for supporting the weight of said tubes entirely from one end including header means having connections with said tubes arranged to provide therethrough a progressive fluid flow path divided into a plurality of fluid flow passes relative to the flow of said heating is associated.

JAMEs D. ANDREW, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 1 Date 1,948,939 Noack Feb. 27, 1934 2,326,513 Bailey, et a1 Aug.,10,-1943 2,184,626 Smith, et a1 Dec. -26, 1939 1,748,113 Danks, et al. .i,' Feb. 25, 1930 9 Emmet Jan, 14,1941 1,289,979 Warriner Dec. 31, 1918 1,921,049 Tompkins Aug. 8, 1933 1,999,984 Bailey, et al Apr. at, 1935 2,158,508 Kuhner "-1 May 1 ,1939

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