US1989127A - Superheater - Google Patents

Description

G. S. BLANKENHORN Jan. 29, 1935.

SUPERHEATER Filed June 26, 1935 2 Sheets-Sheet 1 INVENTOR.

ATTORNEY-5.

Jan. 29, 1935. G. s. BLANKENHORN SUPERHEATER Filed June 26, 1935 2 Sheets-Sheet 2 INVENTOR.

Patented Jan. 29, 1935 SUPERHEATEB,

'George S. Blankenhorn, Pasadena, Calif. Application June 26, 1933, Serial No. 677,606

Claims.

The present invention relates in general to improvements in the art of generating steam, and relates more specifically to improvements in the construction and operation of steam superheaters 5 adapted for cooperation with boilers of various types.

Generally defined, an object of the present invention is to provide an improved steam superheater which is simple and compact in construction, and which is moreover highly efiicient in operation. i

It has heretofore been proposed to provide various forms of superheaters adapted for direct cooperation with the so-called locomotive type of fire tube boiler, and perhaps the most practical of these relatively inefficient prior devices, is a superheater wherein a number of auxiliary steam confining and superheating pipes; are disposed directly within the delivery portions of enlarged fiues or fire tubes extending longitudinally through the boiler, and are connected to headers disposed within the smoke box beneath the stack. This prior superheating device however possesses numerous objectionable features including the following. In order to accommodate the superheater piping and headers, the boiler must be specially constructed originally, and the device cannot be installed in standard boilers of various types. prior device makes it impossible to remove soot and the like from within the boiler tubes or fiues wherein the superheater elements are located,-

and it is also impossible without disturbing the superheater elements, to clean the external or water sides of the boiler fiues since the ordinary rattler cannot be utilized for scale removal. The use of this prior superheater also necessitates enlargement of the smoke box for insertion of the superheater headers, and the special large boiler flues cannot bererolled without removing the superheater elements therefrom. The prior device furthermore is not conveniently and automatically drainable, and because of the location of the heat transfer pipes Within low temperature discharge portions of the fire tubes, a great amount of surface and long pipes are required thereby making the apparatus very costly. A boiler adapted to accommodate one of these prior superheaters must also be provided with properly proportioned and disposed smaller fiues, in addition to the large tubes containing the superheater elements, in order to effect proper distribution of the hot gases through all of the tubes in the boiler, and since these small flues are considerably smaller than those ordinarily u'sedjthey The installation of this materially restrict the available draft mak ng the latter insufiicient to compensate for the restriction and thus greatly reducing the boiler capacity. These and other objectionable features. are. present not only in the particular typeof prior steam I superheater for locomotive boilers. specifically referred to, but are also found in other prior devices of this kind which are associated directly with the boiler, thus making .the prior apparatus relatively undesirable, complicated, inefficient and expensive.

It is a morespecific object of the presentinvention to provide improved steam superheating apparatus Whichobviates all of the above-mentioned objectionable features, andwhich may be conveniently appliedto any standard fire box boiler with only minor changes which can be readily made in the field. I

Another specific object of the invention 'isfto provide an improved device capableof producing a high degree of superheat with arelatively small amount of heat transfer surface. f

A further specific object of the. invention is to provide an improvedsuperheater which can be readily installed by any boiler maker, and wherein the heat transferring elements may be easily and are effectively braced when assembled.v

An additional specific objectof the invention is to provide superheating apparatus in which, no damage will result from bursting of the steam confining elements, and wherein the various passages may be conveniently and completely drained. Still another specific object of the invention is to provide an improved superheater soconstructed thatregulation of the degree of superheat will take place automatically, and wherein the amount of superheatmaybe quickly varied either byincreasing or decreasing the heat transfer surface, or by, merely changing the location of the heat transfer elements through simple'adjustmentof parts. j

Another specific object of the invention is to provide an improved steam superheater which automatically fioods itself when the boiler is shut are required between the'steam conducting 'c'on- Quits, thus meeting with the m'.ost.-hig'hly ap.;'

proved present day practice and boiler design codes.

Still another specific object of the invention is to provide an improved superheater which can be installed primarily within the fire-box of a boiler, thereby permitting unobstructed cleaning and replacement or re-rolling of the boiler fines, and also enabling transportation of the boiler as a unit without disturbing the superheater.

An additionalspecific object of the invention is to provide an improved steam superheating system wherein the conduits and pipes are effectively protected against leaks due to expansion" and contraction.

Another specific object of the invention is to provide an improved furnace' construction espe-- cially cooperable with a superheater disposed within the fire box of a boiler, and adapted to most effectively distribute the heat so-as to-in-" crease the superheater capacity and efficiency to a maximum. j

A furtherspecific object of the invention is tcrpr'ovide variousfimprovements in the construction an'din the mode of operating superheaters, whereby the cost of construction, installation and maintenance" is reduced to a' minimum, whereas the capacity and efficiency are enhanced toa maximum.

\ These and other-objects and advantages will be'a'pparent" from the following detailed description.

A clearconception' of embodiments'o'f. the. variousnovelfeatures; and of'the 'mode of constructing andiof' operating the improved superheaters and'boilersequippedtherewith, may be-had by refrri'ng'to the drawings accompanying andforming a part ofthis'specific'ation in- Which like reference characters designate the. same or similar parts in the several views;

Fig. 1 is*a somewhat diagrammatic part sectionalside elevation of alocomotive type of boiler having. one form of the improved superheater al Pliedithereto;

Fig. 2'is a transverse vertical section through the-fireT-boxof the'boiler and-through the superheater" of- Fig. 1-, taken along the line- 22;

Fig. 3, is' a topvi'e'w of the boiler andsup'erheater of Figs. 1 and 2';

Fig; 4 anenl'arged section through-a fragmerit of. the boiler and one of the superheater portions taken along the line 4-4 of Fig. 5;

Fig: 5 is a side elevation of the superheater portion of Fig.4; v

Fig. 6 is a part sectional top view of the boiler fragment and superheater portion; the section being taken along the line'66 of Fig. 5;'

I Fig. 7*is asimilarly enlarged section through a fragment of the boiler and a modified form of superheater structure; I

Fig.8 isla top view of a boiler having a modifled form of, superheater assemblage associated therewith;

Fig... 9v isapart sectional. side elevation of the boiler andLniodified' superheater. of Fig. 8;

v Fig.. 10 is apart sectionalside elevation of a boiler: having still another form of superheater applied; thereto;

Fig. 11 is a rear view of the'boiler andv superheaterof Fig. 10;

Fig; 1-2- is' a' fragmentary part sectional :side elevationof a boiler having a further modification ofi the improved superheater appliedthereto;

Fig; 13: is: an enlarged transverse. section through; oneof: the superheater elements, thesection being taken along the line 1313 of Fig. 1; and

Fig. 14 is a similar section through the superheater element, taken along the line 1414 of Fi 1.

While the invention has been shown and described herein as being specifically applied to a locomotive type of fire-tube boiler especially adapted for oil field service, it is not intended tolimit .the scope by such specific disclosure, since some of the features may obviously be applied to superheaters for other classes of service.

Referring to the embodiment of the invention illustrated in Figs. 1 to 3 inclusive, the boiler is of relatively standard construction comprising a substantially cylindrical horizontally disposed shell l5-having front and rear tube sheets 16, 1'7 therein'ja smoke box 18 located within the front portionloflthe shell 15 and communicating with a stack in the usual manner; a plurality of substantiallyhorizontal fire-tubes or fiues 19 connectingthe tube sheets 16, 17; a fire-box 20 located within the rear portion of the shell 15 and having a combustion chamber communicatingwith'the-rear ends of' the flues 19; a firebrick lined furnace 21 disposed directly beneath the fire box 20 and either above or below the ground line; and another brick lined pit 22 normally covered by a grating (not shown) and located rearwardlyofthe pit 21, the second pit 22 having a valve controlled gas line 23 extending therethrough and" being omitted-when the furnace is above the ground line. The top of the boiler shell 15-isprovidedwith the usual-steam dome 24, and-the space surrounding the fines 19 elements of the boiler installation Whichis shown more or less diagrammatically in the drawings.

The improved superheater specifically illustrated in-Figs. l to 6 inclusive and in Figs. 13 and 14', consists of two portions or sections, one of whichis disposed oneach side of the fire-box 20,

and bothofwhich communicate with the steam dome 24 and with a common steam delivery pipe, in a manner subsequently described. Each of the superheater sections comprises a substantially vertical rear inlet header 28, a substantially vertical front discharge header 29 spaced from and disposed somewhat lower than the corresponding inlet header 28, and a series of S-shaped tubular heat transfer elements 30 connecting the headers 28, 29 and having horizontal superimposed" substantially parallel portions. The headers 28, 29 are located outside of the boiler adjacent the fire-box 20, and the elements 30 extend laterally from these headers through stay-tubes 31 permanently connecting the fire-box side walls with the outer boiler wall, into the combustion chamber wherein the horizontal elongated portions of the elements 39 are located. The heat transferring horizontal portions of the S-shaped elements may be spaced at any desired distance,

from the inner surfaces of the side walls of the fire-box- 20, dependent upon the degree of superheating required, but the central and top portions of the combustion chamber are preferably maintained free from obstruction so that the hot gases of combustion are free to enter the central toward the superheater elements and to utilize and topflues 19, as will be apparent from Fig. 2. a The upper end of each inlet header 28 is connected byaa curved pipe 32', to a common steam supply pipe 33 communicating with the "steam dome 24, and the pipe 33 has a control valve 34 therein adjacent to the dome. The upper end of each discharge header 29 is likewise connected by a curved pipe 35, to a common delivery pipe 36 through a pipe fitting 37 mounted forwardly of the dome 24 and having a safety valve 38 associated therewith; The final delivery pipe 36 may also be provided with a control valve 39 and is adapted to conduct the superheated steam to any desirable source of utilization. It should be noted that the steam pipes 32, 33, 35,36 are preferably gradually curved at the bends therein, in order to compensate for. expansion and contraction thereof due to changes in temperature, thereby header by welding or otherwise, as shown in Figs. 1 4 and 6.

This'channel bar 41 is penetrated by the tubular elements 30, some distance away from the corresponding header 28, 29, thereby relieving the joints from lateral pressure and assisting in the support of the superheaterelements 30. An attaching bar 42 is secured to the upper outer portion of each channel bar 41 by welding or. otherwise, and a reaction bar 43 is likewise secured to the lower outer face of each bar 41, the

upper bar 42 being slotted for adjustable attachment to the outer shell 15 of the boiler'with the aid of cap screws 44 as indicatedin Figs. and

6. The position of the superheater elements 30 within the combustion, chamber, may obviously tween the bars 42, 43 and the adjacent boiler shell15, in order to vary the'degreeof superheat and to secure maximum efiiciency.

If so desired, the stay-tubes 31 may be omitted as in Fig. 7, and the superheater elements 30 may be rolled andexpanded into firm engagement with the boilershell and the adjacent Wall of the fire-box as indicatedat the joints 45, 46. These rolled joints 4 5, 46 will additionally assist in supporting'the superheater, although the use ofthe stay-tubes 31 will permit more convenient adjustment of the superheater portions relative to the boiler.

The lower coils of the superheater may also be protected against the hottest flame, by providing a covering 47 as shown in Figs. 1, 2 and 4, and the elongated horizontal portions of the heat transfer elements 30 may be provided with front and rear braces 48, 49 shown generally in Fig. 1

and more in detail in Figs. 13 and 14. The forward braces 48 shown in Fig-14, are forked and adapted for insertion between the adjacent superimposed portions of the element 30, while the rear braces '49 shown in Fig. 13, have hooked ends adapted to prevent spreading of the superimposed element portions. These braces 48, 49 may be applied after the superheater has been installed, and to various sections of the elements 30..

with suitable stop and safety valves.

In order to improve the delivery of hot gases the radiant heat in a most effective manner, the I fioor of the pit 21 may be formed as shown in Figs. 1 and 2, with a tapered deck 50. This deck-T: 5 50 will direct the hot gases and the radiant heat from the lower portion of thepit 21 upwardly and outwardly directly toward the heat transfer elements 30, in an obvious manner. ..The deck 50may be formed with more or less slope in order '10 to most effectively radiate theheat.

While it is desirable, in order to secure most effective superheating, to have the elements 30 exposed to the hot gases within the fire box, the disposition of the inlet and discharge headerselfi communicating with the elements 30, maybe varied to a considerable extent. In the modified superheater of Figs. 8 and 9, the inlet and discharge headers 28', 29 are disposed on opposite sides of the boiler adjacent the smoke- box 18, 20 and the heat transfer elements 30 extend through superimposed side fiues 19 of the boiler into the fire-box 20 adjacent the opposite side walls thereof. The headers 28, 29 are constructed substantially as previously described, and the inleti headers. 28' communicate with the steam dome 24 through branch pipes 32 and a common supply pipe 33', while the discharge headers 29' again communicate with a common delivery pipe 36 through branch pipes 35'. The supply and= delivery pipes 33, 36 may also be provided with suitable stop and safety valves as previously described, and this modified assemblage avoids necessity of penetrating the water chamber of the boiler and may thereforebe more readily installed than that of Figs. 1, 2 and 3.

In the further modified superheater assemblage of Figs. 10 and 11, the inlet headers 28"are disposed at the extreme rear of the boiler near the door 25, while the discharge headers 29" are 10- cated on opposite sides of the boiler near the smoke box 18. The major portionsof the heat transferelements 30" which connect the headers 28", 29", are again disposed within and near the opposite sides of'the combustion chamber of the fire-box 20, and these elements 30 extend forwardly through the boiler flues 19' as indicated. The inlet headers 28" communicate with the supply pipe 33 through branch pipes 32", while the discharge headers 29" likewise communicate with a common delivery pipe 36 through branch pipes 35", and these pipes may also be provided In this assemblage, the use of stay-tubes 31 for accommodating the superheater elements 30", may again-" be dispensed with, since these elements'may be passed from the inlet headers 28" into the combustion chamber through the inspection opening which is normally closedby the door 25. and from H the interior of the boiler to the discharge headers 29" through the smoke-box wall. v i

In the modified assemblage of Fig. 12, the inlet and discharge headers 28", 29" may be nested in groups at opposite sides of the forward portion of the fire-box 20, and the elements 30" are of U-shape instead of S-shaped as in Fig. 1. Instead of utilizing only two heat transfer elements asin the previous type, three or more elements 39" may be employed in each portion of the superheaterQ As illustrated, only one super-. heater unit is utilized at one side of the fire-box 20, and the inlet header 28" of this single unit communicates directly with the steam dome 24 through a supply pipe 32", whereas the outlet header 29 is in direct communication with the "delivery pipe 35". It will be apparent that while Fig. 12 alone discloses the -use of a single superheater unit, the other types of units illustrated may also be utilized singly instead of in sets o'ftwo.

While thenormal mode of installing and of utilizing the improved superheaters will be "readily apparent from the foregoing description, fitmaybe desirable to'present a short'description -:of the 'operation as applied to Figs. 1, 2 and 3, it

being understood that the other modified forms operatesin substantially the same manner. When the boiler is operating, the burner 26 is efiective in delivering combustible gas to the fire-pit 21, and: air is entering this pitthrough the arch open- .ing 27. The mixture of gas and air thus admitted, is ignited and the gases of combustion pass upwardly through the fire-box 20 along a c'ircuituous ,path, eventually passing forwardly through the fire-tubes or flues 19 to the stack. During passage of these hot gases through the xfire-box 20 and fiues 19, heat is absorbed by the watersurrounding the fire-box and flues, and the generated'steam rises into the dome 24. From the dome 24, the steam passes through the pipes .33, '32 to the inlet headers 28 of the superheater from vwhence it is distributed to the tubular elements 30. In passing through the elements 30, the temperature of the steam is increased above thetemperature of saturated steam of the same .pressuraby' virtue of the'fact that these relatively smaller tubes are exposed directly to the hot gases within the fire-box 20, and the superheated steam iseventually delivered from the discharge headers29 to the final delivery pipe 36. The deck 50 functions to direct the hot gases and the radiant heat directly against the superheater elements30, and these elements may be protected against the excessively hot gases by providing coverings 4'7 for the lowermost coils.

When the-boiler is shut down, the superheater headers and coils, automatically fill with water,

so that the elements 30 will not be destroyed by burningin case the boiler is restarted with a hot fire. This automatic filling of the superheater with water when the boiler is shut down, results from the location of the coils and headers so that when the boiler cools down, the superheater elements act as condensers, the cold air flowing through the burner arch constituting the cooling medium which comes in direct contact with the tubular elements 30. This cooling air acts to quickly condense the steam within the superrheater elements, headers, and the piping communicating therewith and located thereabove, and the water of condensation thus produced has been foundto be sufficient to produce rapid flooding and complete filling of the horizontal tubular elements 30 of the superheaters. The superheater units may also be quickly drained, if desired, by opening the drain valves preferably applied to the lowest portions of the lower discharge headers 29 as shown in dotted lines in Fig. 1, and the'operation of the improved device is entirely automatic since the elements 30 are disposed within the fire-box 20, accidental bursting of an element will do no material damage, and the ruptured element can be readily replaced. By avoiding the use of welded joints in the steam passages, danger of bursting and leakage is reduced toa minimum, and the capacity and efficiency of the superheater units may be quickly varied and enhanced, by properly, adjusting the position of the superheater elements.

The improved superheater is moreover simple :and compact in construction, and has proven highly efficient in-commercial operation. =It is obviously readily applicable to old. or new boilers,

either in the field or at thefactory, by any boiler maker 'capable of rolling or expanding boiler tubes-and does not in any manner interfere with the normal use and cleaning of the boiler. The application of the improved superheater to a boiler necessitates only minor changes, and doesnot require the use of other than standard flues in the boiler structure. The piping arrangement shown in' Figs. 1, 2 and 3 not only presents a neat and -mechanical appearance, but' guards against leakage due to expansion and contraction, and

the elements 30 may be held against warping or.

other displacement .by the retainers of Figs. '13 and 14. Theimproved mounting for the headers 28, 29, shown in Figs. 4 to '7 inclusive, facilitates installation of :the units and also adjustment thereof, and a-boiler'equipped'with the improve-,

Patent:

1. In a superheater for a fire-tube boiler having a fire-box and heating 'flues extending horizontally therefrom, a pair of substantially upright laterally spaced headers disposed externally of the fire-box, and a tubular heating element connectingsaid headers and comprising superimposed communicating conduit sections disposed within 'the fire-box in substantially the horizontal planes'of some of the flues, said conduit sections being exposed directly to the heating gas and being located closely adjacent to and extending along the side wall of the fire-box substantiallythe entire length ofthe-latter.

2. In a superheater for a fire-tube boiler having a fire-box and heating flues extending horizontally therefrom, a pair of substantially upright laterally spacedheaders disposed externally of the fire-box on-each of the opposite sides thereof, and a tubular heating element connecting each pair of said headers and comprising superimposed communicating conduit sections disposed within the fire-box in substantially'the horizontal planes of some of the fiues, eachof said conduit'sections beingexposeddirectly to the heating gases and being located closely adjacent to and extending along the adjacent side wall of the fire-box substantially the entire length of the latter.

3. In a superheater for a fire-tube boiler having a fire-box and heating fiues extending horizontally therefrom, an inlet header communicable directly with the steam space of the boiler, an outlet header disposed at a lower level than said inlet header, said'headers being disposed substantially upright and externally-of the fire-box, and a tubular heating element connecting said inlet header with a lower portion of said outlet header and comprising superimposed communicating conduit sections disposed within the fire-box in substantially the horizontal planes of adjacent flues, said conduit sections being exposed directly to the heating gases and being located closely adjacent to and extendingalong the side wall of the'firebox substantially the entire length of the latter.

4. In asuperheater for a fire-tube boiler having a fire-box and heating flues extending horizontally therefrom, an inlet header on each side of the boiler communicating directly with the steam space thereof, an outlet header on each side of the boiler disposed at a lower level than the corresponding inlet header, and a tubular heating element connecting each set of said headers and comprising superimposed communicating conduit sections disposed within the fire-box in substantially the horizontal planes of the adjacent flues, each of said conduit sections being exposed directly to the heating gas and being located closely adjacent to and extending along the adjacent side wall of the fire box for substantially the entire length of the latter.

5. In a superheater for a fire-tube boiler having a fire-box and heating fiues extending horizontally therefrom, steam supply and discharge conduits disposed externally of the fire-box, and a tubular heating elementconnecting said conduits and comprising superimposed communicating conduit sections of relatively small cross-sectional area disposed within the fire-box substantially in alinement with some of the flues, said conduit sections being exposed directly to the heating gas and being located closely adjacent to and extending along the side wall of the fire-box for a con siderable distance.

GEORGE S. BLANKENHORN.

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