US3269362A

US3269362A - Once-through type boiler

Info

Publication number: US3269362A
Application number: US450126A
Authority: US
Inventors: Engler Otto
Original assignee: Vereinigte Kesselwerke AG
Current assignee: Vereinigte Kesselwerke AG
Priority date: 1964-04-25
Filing date: 1965-04-22
Publication date: 1966-08-30
Anticipated expiration: 1983-08-30
Also published as: DE1257792B

Description

0. ENGLER Aug. 30, 1966 ONCE-THROUGH TYPE BOILER 2 Sheets-Sheet 1 Filed April 22, 1965 FIG INVENTOR film; Z75 BY M3221! $5 ATTORNEY Aug. 1966 o. ENGLER 3,269,362

ONCE-THROUGH TYPE BOILER Filed April 22, 1965 2 Sheets-Sheet 2 INVENTOR F/G. 2 0m 2;;

ATTORNEY United States Patent 12 Claims. (31. 122-435 The present invention relates to a once-through type boiler, that is to a boiler without steam drum in which the water is forced into a single circuit of one or several tubes and steam is delivered at the other end.

Once-through type boilers are known in the art and it is also known to construct the furnace chamber of such a boiler, with which the burner means communicate, from helically formed tubes which contact each other along the length thereof and which are welded together along the contacting portions thereof. In such a boiler, the water fed into the lower ends of the helically arranged tubes is heated up in the region of the lower end of the furnace chamber and the heated up water is gradually transformed into steam in an intermediate portion of the tubes forming the furnace chamber, while at the region of the upper end thereof the thus formed steam is super-heated. The volume of the medium flowing through the tubes increases therefore from the lower to the upper end of the furnace chamber considerably. It would therefore be desirable to increase the inner diameter of the tubes forming the upper portion of the furnace chamber, however this is not possible since large diameter tubes would not withstand the internal pressure they are subjected to.

Furthermore, if the wall of the furnace chamber with which the burner means communicate is exclusively formed by the aforementioned helically arranged tubes, the heat absorption of these tubes becomes very considerable so that a considerable difference between the tube portions forming the lower part of the furnace chamber and the tube portions forming the upper part of the furnace chamber will result, especially since the lower portions of the tubes are flown through by water fed into the boiler, whereas the upper portions are flown through by hot steam. While this difficulty can in part be overcome by sufiicient speed of the medium flowing through the tubes, experience has shown that especially in the upper portion of the furnace chamber overheating of the tubes will occasionally occur which may lead to a damage of the same.-

It is an object of the present invention to overcome the aforementioned difliculties encountered in once-through type boilers in which the cylindrical outer wall of the boiler is formed by helically wound tubes through which the fluid medium passes.

It is a further object of the present invention to limit the heat absorption of the helically wound tubes forming the cylindrical wall of the boiler so as to reduce the difference between the heat expansion of the lower portions of the tubes and the upper portions thereof and to prevent overheating of the tubes in the region of the upper end of the boiler.

It is an additional object of the present invention to provide for a once-through type boiler of the aforementioned kind which is relatively simple in construction so that the boiler can be manufactured at reasonable cost and will stand up trouble-free under extended use.

With these objects in view, the once-through type boiler of the present invention mainly comprises an outer upright substantially cylindrical wall formed by a plurality of tubes extending substantially parallel in contact with each other in helical form from the lower to the upper end of the cylindrical wall and being welded to each other, a substantial vertical separating wall extending trans- 3,269,352 Patented August 30, 1966 versely through the interior of the cylindrical wall and being formed by a plurality of substantially vertical tubes welded together through a substantial portion of the length thereof so that the vertical wall divides the interior of the cylindrical wall into a furnace chamber and a heat exchange chamber. The aforementioned tubes of the vertical wall are arranged spaced from each other at an upper portion of the wall to provide communication between the furnace chamber and the heat exchange chamber at an upper portion of the separating wall. The boiler includes further burner means communicating with the interior of the furnace chamber, heat exchange means in the heat exchange chamber, and tubular means connecting the tubes of the cylindrical wall, the tubes of the separating wall and the heat exchange means to each other for passage of fluid in a continuous pass therethrough.

It is to be understood that the term cylindrical wall as used in the specification and the claims includes an outer wall of circular configuration as well as an outer wall of square or rectangular configuration having rounded corners.

The arrangement according to the present invention has the advantage that each convolution of the substantially helically wound tubes forming the outer boiler wall passes through zones at opposite sides of the separating wall dividing the interior of the outer wall into the furnace chamber and the heat exchange chamber, that is through a greatly heated zone and through a zone heated to a lesser extent, so that the heat transmitted to the tubes forming the outer wall of the boiler is reduced in comparison to known arrangements. The increase of the volume of the medium flowing through the helically arranged tubes is thereby reduced so that these tubes may be formed with uniform cross section. Furthermore, since the tubes forming the outer wall are arranged at a relative small angle inclined to the horizontal, a convolution passing at one side of the separating wall through a relative hot part of the furnace chamber will pass at the other side of the separating wall through a relative cool part of the heat exchange chamber so that adjacent tubes will be heated up to substantially the same extent and so that the heat ex pansion of adjacent tube portions will be substantially the same.

The tubes forming the cylindrical wall as well as the tubes forming the separating wall are preferably fin tubes arranged in such a manner that the free edges of the fins of adjacent tubes abut against each other and are welded to each other at the abutting edges.

Preferably, the boiler includes also annular reinforcing means surrounding the cylindrical wall and operatively connected thereto for preventing bulging thereof. Preferably the heat exchange means extend transversely through the heat exchange chamber with opposite portions of the heat exchange means respectively facing part of the cylindrical wall defining the heat exchange chamher, and the separating wall, and the construction includes preferably further bracing means between said opposite portions of the heat exchange means and the aforementioned part of the cylindrical wall at one hand and the separating wall at the other hand so that the separating wall is also supported intermediate the ends thereof.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a greatly simplified flow diagram of a once through type boiler according to the present invention;

FIG. 2 is a longitudinal schematic cross section through the boiler of the present invention; and

FIGS. 3 and 4 are detailed constructions of the boiler, shown partly in cross section and drawn to an enlarged scale.

FIG. 1 shows a greatly simplified schematic flow diagram of the once-through type boiler according to the present invention in which some parts of the boiler are omitted for reasons of simplification. As schematically shown in FIG. 1 feed water is fed by by a pump P in direction of the arrow A into the lower ends of helically arranged tubes H, only one is shown in FIG. 1, which are arranged in a manner as will be described in further detail latter on to form a substantially cylindrical outer wall of the boiler. The upper ends of the tubes H are connected to a collector located at the lower end of the boiler with which a plurality of substantially vertically extending tubes S communicate at the lower ends thereof and the vertical tubes S are arranged in a manner as will be describe-d in further detail later on to form a separating wall dividing the interior of the cylindrical wall formed by the helically arranged tubes A into a furnace chamber shown at the left side of FIG. 1 and in a heat exchange chamber at the right side, as viewed in FIG. 1, of the transverse wall formed by the vertical tubes S. Burner means communicate with the lower region of the furnace chamber so that the flames and hot combustion gases developed by the burner means pass in upward direction as shown by the dotted arrows B through the furnace chamber and the upper portion of the vertical wall S is constructed to permit passage of the combustion gases through the upper region of the vertical wall so that the combustion gases pass in downward direction as indicated by the dotted arrows through the heat exchange chamber to pass from the lower ends thereof into a flue. The feed water fed into the lower portion of the tubes H is heated up in the .lower portion of the boiler and the heated up water is gradually transformed into steam during the forced passage of the water through the helically wound tubes from the lower to the upper end of the cylindrical wall. Obviously, the portions of the helically wound tubes H which are located at the right side, as viewed in FIG. 1, of the separating wall S will be heated up to a lesser extent than the portions of the helically wound tubes which are located at the left side of the separating wall and therefore the total heat absorption of the helical tubes forming the cylindrical wall of the boiler will be less than than it would be in the absence of the separating wall. The difference between the terminal expansion of the tube portions of the helical tubes at the lower part of the cylindrical wall and the upper part thereof is thereby greatly reduced.

FIG. 2 shows the construction of the boiler of the present invention in further detail. As can be seen from FIG. 2, the boiler of the present invention comprises an upright substantially cylindrical wall formed by a plurality of fin tubes 13 extending in helical form substantially parallel to each other from the lower to the upper end of the cylindrical wall. It is mentioned that the angle of inclination of the tubes 13, that is the angle the tubes include with the horizontal is in the actual construction much smaller than shown in FIG. 2. The fin tubes 13 have diametrically opposite fins 13 extending in longitudinal direction of the tubes (FIG. 4) and arranged so that the free edges of the fins 13' of adjacent tubes 13 abut against each other and are Welded together along the abutting free edges thereof. The lower ends of the helically wound tubes 13 communicate with an annular inlet collector 12, whereas the upper ends of the tubes 13 communicate with an annular outlet 14. The boiler of the present invention further comprises a substantially vertical separating Wall extending transversely through the interior of the cylindrical wall and being formed by a plurality of substantially vertical fin tubes 19 extending substantially parallel to each other and each having diametrically opposite fins abutting against each other along the free edges thereof and welded together along the abutting edges in the same manner as the fins in the helically arranged tubes 13 are welded together. The vertical wall formed by the fin tubes 19 divides the interior of the outer wall formed by the helically arranged tubes 13 into a furnace chamber F, located at the left side of the vertical wall, as viewed in FIG. 2, and in a heat exchange chamber H located to the right side of the vertical wall. The upper portions 21 of some of the vertical tubes 19 are located in the plane of the vertical wall formed by the tubes 19, whereas upper portions 22 of adjacent tubes which alternate with the upper tube portions 21 are bent out of the plane in which the separating wall is located so that the tube portions 22 are spaced from the tube portions 21 providing thereby openings through which the upper end of the furnace chamber F will communicate with the heat exchange chamber H. The tubes 19 forming the vertical separating wall communicate at the lower ends thereof with an inlet collector 18 and at the upper ends thereof with an outlet collector 20.

Heat exchange means are located in the heat exchange chamber H of the boiler. These heat exchange means comprise tubular economizer means 3 located in the lower portion of the heat exchange chamber, pre-superheater means 25 located in an intermediate portion of the heat exchange chamber, and additional superheater means 31 located in the upper part of the heat exchange chamber. The aforementioned described elements are connected together and are supplied with a fluid means in the fol-lowing manner: a

A feed water pump P feeds water from a reservoir not shown in FIG. 2 into the lower inlet end or inlet collector 2 communicating with the lower end of the tubular economizer 3 located in the lower portion of the heat exchange chamber. The upper end of the economizer 3 communicates with an outlet collector 4 of the economizer and the outlet collector 4 is connected by a tube 5 to an inlet collector 6 located at the bottom of the boiler. A plurality of tubes 7 extend transversely through the lower end of the furnace chamber F from the bottom inlet collector 6 to the bottom outlet collector 8 and the latter is connected by tubes 9 to a header 10 located beneath the bottom of the furnace chamber and communicating through a plurality of tubes with the annular inlet collector means 12 for the spirally arranged tubes 13 forming the cylindrical wall of the boiler. A plurality of tubes 15 lead from the annular outlet collector 14 to an injection cooler 16 which in turn is connected by tubes 17 to an inlet collector 18 With which the lower ends of the tubes 19 forming the separating wall communicate. The outlet collector 20' with which the upper ends of the tubes 19 communicate is connected by a plurality of tubes 23 to an inlet collector 24 which communicates with the lower end of the pre-superheater 25. An outlet collector 26 in communication with the upper end of thepre-superheater 25 communicates through tubes 27 with an additional cooler 28 and the latter communicates through a plurality of tubes 29 with an inlet collector 30 communieating with the lower end of the additional superheater 31. The upper end of the additional superheater 31 communicates with a plurality of tubes 32 which extend transversely through the upper end of the cylindrical wall and which lead to a final outlet collector 33. The transverse tubes 32 are not Welded together and a cover not shown in FIG. 2 extends over and closes the upper end of the cylindrical wall.

Burner means 35 pass through a lower portion of the cylindrical wall which faces the separating wall and the burner means 35 communicate with the interior of the furnace chamber F. The specific construction of the burner means 35 and the manner in which the inlet ends of these burner means are passed through the cylindrical wall of the boiler does not form part of the present i114 vention and burner means using pulverized coal, as well as oil burners may be used in connection with the boiler of the present invention.

A plurality of annular reinforcing means spaced from each other in axial direction of the outer wall formed by the tubes 13 are provided which surround the outer wall operatively connected thereto to prevent bulging thereof. The annular reinforcing means include l-beams 36 having inner flanges 36 (FIG. 3) engaged at upper and lower edges thereof by claws 37 formed on plates 38 which are at the inner longitudinal edges thereof Welded to longitudinal extended tie bars 39, extending in longitudinal direction substantially through the whole length of the outer wall formed by the tubes 13 and abutting with the inner surface thereof against the outer surface of the tubes 13. The tie bars 39 are anchored at the upper ends thereof to a supporting structure 40 surrounding the actual boiler. The tie bars 3% are preferably connected by links 41 to upright I-beams 45 forming part of the supporting structure of the boiler. Each of the links 41 preferably comprises, as shown in FIG. 4, two short bars 32, arranged spaced from each other and substantially normal to the tie bar 39 and welded to the latter and a similar bar 43 arranged between the bars 42 and Welded to the upright I-beam 4-5. The short bars 32 are formed adjacent the free ends thereof with bores therethrough aligned along a common axis in which a pin 44 is press fitted which passes through an elongated slot 43 in the bar 43. The links 41 connect therefore the tie bar 39 to the upright I-beams 45 pivolally about the axis of the pin 4 S and also movable through the length of the slot 43 toward and away from the upright l-beam. A sheet metal shell 46 is preferably held by spot welding or the like on the upright I-beams surrounding the outer wall of the boiler and lagging of heat insulating material 47 is interposed between the sheet metal 46 and the outer surface of the tubes 13 forming the boiler wall so that the latter is properly heat insulated. The outer Wall of the boiler formed by the fin tubes 13, as well as the separating wail formed by the fin tubes 19 is supported at the upper end thereof at 34 to the supporting structure 49 in any convenient manner not forming part of the present invention. The separating Wall formed by the tubes 19 is preferably also connected by links 41, similar to the links shown in FIG. 4, to the tubes of the economizer 3, the tubes of the pre superheater 25 and the additional superheater 31 and the tubes of the aforementioned elements are connected at the opposite ends preferably also by similar links 41 to the outer wall of the boiler formed by the tubes 13.

The operation of the boiler above described will be obvious from the preceding description. Feed water is fed by the pump P in the inlet collector 2 of the economizer 3. The speed with which the feed water is fed into the boiler is at full load approximately between 1.9 and 2.5 meters per second. During operation of the burner means 35 the feed water is preheated in the economizer 3 and passes then in the manner as described above into the inlet collector E2 to flow from there in upward direction through the plurality of helically arranged tubes 13 forming the outer wall of the boiler. In the lower portion of the boiler the water is further heated to be in intermediate section of the outer wall gradually transformed into steam so that steam will collect in the outlet collector 14 at the upper end of the outer boiler wall from where the steam passes into the inlet collector 18 at the bottom of the separating wall to be further superheated during the passage through the tubes 1h and the superheated steam is then guided through the superheater 25 and the additional superheater 31 to pass through the outlet collector 33 to a point of use.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of once-through type boilers differing from the types described above.

While the invention has been illustrated and described 6 as embodied in once-through type boiler having an outer wall formed by welded together helically arranged fin tubes, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of tubes extending substantially par allel in contact with each other in substantially helical form from the lower to the upper end of said cylindrical wall and being welded to each other; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical tubes welded together through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical Wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said. separating wall; burner means communicating with the interior of said furnace chamber; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

2. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; a substantially vertical separating Wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallell to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical Wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall; burner means communicating with the interior of said furnace chamber; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating Wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

3. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical Wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; a substantially ver* tical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat ex change chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating Wall; burner means communicating with the interior of said furnace chamber and arranged to pass through a portion of said cylyindrical wall facing said separating wall; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

4. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical Wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall; burner means communicating with the interior of said furnace chamber; tubular heat exchange means extending transversely through said heat exchange chamber and facing with opposite portions thereof, respectively, part of said cylindrical wall defining said exchange chamber and said separating wall; bracing means connecting said opposite portions of said heat exchange means respectively to said part of said cylindrical wall and said separating wall; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

5. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; annular reinforcing means surrounding said cylindrical wall and operatively connected thereto for preventing bulging thereof; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall; burner means communicating with the interior of said furnace chamber; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

6. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; a plurality of annular reinforcing means spaced from each other in axial direction of said cylindrical Wall and surrounding the latter operatively connected thereto for preventing bulging thereof; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall; burner means communicating with the interior of said furnace chamber; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

7. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and welded to each other; a plurality of annular reinforcing means spaced from each other in axial direction of said cylindrical wall and surrounding the latter operatively connected thereto for preventing bulging thereof; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical Wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating Wall; burner means communicating with the interior of said furnace chamber; tubular heat exchange means extending transversely through said heat exchange chamber and facing with opposite portions thereof, respectively, part of said cylindrical wall defining said exchange chamber and said separating wall; bracing means connecting said opposite portions of said heat exchange means respectively to said part of said cylindrical wall and said separating wall; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

8. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical Wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to said upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded to each other through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical Wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall, the outermost of said fin tubes forming said separating wall being at least in part welded to said helical tubes forming said cylindrical wall; burner means communicating with the interior of said furnace chamber; heat exchange means in said heat exchange chamber; and tubular means connecting the tubes of said cylindrical wall, the tubes of said separating wall and said heat exchange means to each other for passage of fluid in a continuous path therethrough.

9. A once-through type boiler comprising, in combination, an outer upright substantially cylindrical wall formed by a plurality of fin tubes extending in substantially helical form substantially parallel to each other from the lower to the upper end of said cylindrical wall with the free edges of the fins of adjacent fin tubes abutting against and Welded to each other; annular inlet collector means for said cylindrical Wall and communicating with the lower ends of said fin tubes forming said cylinderical wall; annular outlet collector means for said cylindrical Wall and communicating with the upper ends of said fin tubes forming said cylindrical wall; a substantially vertical separating wall extending transversely through the interior of said cylindrical wall and being formed by a plurality of substantially vertical fin tubes extending substantially parallel to each other with the free edges of the fins of adjacent fin tubes abutting against and welded together from the lower ends of the vertical tubes through a substantial portion of the length thereof, said vertical wall dividing the interior of said cylindrical Wall into a furnace chamber and a heat exchange chamber, said tubes of said vertical wall being spaced at upper portions thereof from each other to provide communication between said furnace chamber and said heat exchange chamber at an upper portion of said separating wall; inlet collector means for said separating wall and communicating with the lower ends of said vertical fin tubes; outlet collector means for said separating wall and communicating with the upper ends of said vertical fin tubes; tubular economizer means located in a lower portion of said heat exchange chamber and having a lower inlet end and an upper outlet end; tubular means providing communication between said outlet end of said economizer means and said annular inlet collector means of said cylindrical wall; tubular means providing communication between said annular outlet collector means of said cylindrical wall and said inlet collector means of said separating wall; tubular superheater means in an upper portion of said heat exchange chamber and having a lower inlet end and an upper outlet end; tubular means providing communication between said outlet collector means of said separating Wall and said lower end of said superheater means; burner means communicating with the interior of said furnace chamber and passing through a lower portion of said cylindrical wall facing said separating wall; pump means communicating with said inlet end of said economizer means for feeding water into the latter; and support means for supporting said cylindrical wall and said separating wall in the region of the upper ends thereof.

10. A boiler as set forth in claim 9 and including heat lagging surrounding said cylindrical Walls.

11. A boiler as set forth in claim 9 and including a plurality of annular reinforcing means spaced from each other in axial direction of said cylindrical wall and surrounding the latter operatively connected thereto for preventing bulging thereof.

12. A boiler .as set forth in claim 9, wherein said tubular means providing communication between said outlet end of said economizer means and aid inlet collector of said cylindrical wall include a plurality of tubes extending substantially horizontally transversely of said annular inlet collector means of said cylindrical wall at the bottom of the latter and each connected at one end thereof to said outlet end of said economize-r means, a header communicating with the other ends of said horizontal tubes, and a plurality of tubes connecting said header to said annular inlet means.

References Cited by the Examiner UNITED STATES PATENTS 2,170,349 8/1939 Bailey 122250 FOREIGN PATENTS 1, 194,599 5/1959 France.

874,063 8/1961 Great Britain.

KENNETH W. SPRAGUE, Primary Examiner.

Claims

1. A ONCE-THROUGH TYPE BOILER COMPRISING, IN COMBINATION, AN OUTER UPRIGHT SUBSTANTIALLY CYLINDRICAL WALL FORMED BY A PLURALITY OF TUBES EXTENDING SUBSTANTIALLY PARALLEL IN CONTACT WITH EACH OTHER IN SUBSTANTIALLY HELICAL FORM FROM THE LOWER TO THE UPPER END OF SAID CYLINDRICAL WALL AND BEING WELDED TO EACH OTHER; A SUBSTANTIALLY VERTICAL SEPARATING WALL EXTENDING TRANSVERSELY THROUGH THE INTERIOR OF SAID CYLINDRICAL WALL AND BEING FORMED BY A PLURALITY OF SUBSTANTIALLY VERTICAL TUBES WELDED TOGETHER THROUGH A SUBSTANTIAL PORTION OF THE LENGTH THEREOF, SAID VERTICAL WALL DIVIDING THE INTERIOR OF SAID CYLINDRICAL WALL INTO A FURNACE CHAMBER AND A HEAT EXCHANGE CHAMBER, SAID TUBES OF SAID VERTICAL WALL BEING SPACED AT UPPER PORTIONS THEREOF FROM EACH OTHER TO PROVIDE COMMUNICATION BETWEEN SAID FURNACE CHAMBER AND SAID HEAT EXCHANGE CHAMBER AT AN UPPER PORTION OF SAID SEPARATING WALL; BURNER MEANS COMMUNICATING WITH THE INTERIOR OF SAID FURNACE CHAMBER; HEAT EXCHANGE MEANS IN SAID HEAT EXCHANGE CHAMBER; AND TUBULAR MEANS CONNECTING THE TUBES OF SAID CYLINDRICAL WALL, THE TUBES OF SAID SEPARATING WALL AND SAID HEAT EXCHANGE MEANS TO EACH OTHER FOR PASSAGE OF FLUID IN A CONTINUOUS PATH THERETHROUGH.