US3277871A

US3277871A - Vapor generating and superheating apparatus

Info

Publication number: US3277871A
Application number: US401192A
Authority: US
Inventors: Erdman A Blum; Jr Albert O Downs; Michael C Santucci
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1964-10-02
Filing date: 1964-10-02
Publication date: 1966-10-11
Anticipated expiration: 1983-10-11
Also published as: GB1117008A

Description

Oct. 11, 1966 E. A. BLUM ETAL 3,277,871

VAPOR GENERATING AND SUPERHEATING APPARATUS Filed Oct. 2, 1964 5 Sheets-Sheet l INVENTORS Erdman A. Blum Alberr O. Downs,Jg'. Mlchael .Sanfuccl 5 Sheets-Sheet 2 pm I 3 I v. i I 1 T r FIG-4 FIG.5

E. A. BLUM ETAL VAPOR GENERATING AND SUPERHEATING APPARATUS Oct. 11, 1966 Filed Oct. 2, 1964 aim.

Oct. 11, 1966 A. BLUM ETAL VAPOR GENERATING AND SUPERHEATING APPARATUS Filed Oct. 2, 1964 5 Sheets-Sheet 5 FIG.7

4 I O O O:

United States Patent 3,277,871 VAPOR GENERATING AND SUPERHEATING APPARATUS Erdman A. Blunt and Albert 0. Downs, .lr., Akron, and Michael C. Santncci, Barberton, Ohio, assignors to The Babcock ll; Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Oct. 2, 1964, Ser. No. 401,192 3 Claims. (Cl. 12251tl) This invention relates generally to vapor generating and .superheating apparatus, especially to those of the kind having a furnace chamber provided with a roof through which fluid heating tubes extend, terminating in an adjacent compartment or chamber. More particularly, the invention relates to an improved insulating roof construction of the type set forth which minimizes leakage of fly ash through the clearance space between the tubes and the edges of the holes in the roof.

The wall structure of conventional vapor generating and superheating units encloses not only a lower furnace chamber, but also an upper chamber or so-called penthouse which is partitioned from the furnace chamber by a horizontally extending furnace roof of refractory construction. As is well known, upright fluid heating tubes extend from the furnace chamber through the furnace roof into the penthouse, where they are rigidly connected to horizontally elongated headers. When heated, the tubes undergo thermal expansion in a downward direction from the point of restraint at the header. Also, horizontal thermal expansion of the header tends to increase the horizontal spacing of the tubes, thus producing a sidewise movement of the tubes which can break up the surrounding refractory and make a path for the leakage of fly ash from the furnace chamber into the penthouse.

One of the objects of the present invention is to provide a refractory roof construction which permits unrestrained longitudinal movement of the upright tubes relative to the roof as a result of thermal expansion; which minimizes leakage of fly ash through the clearance space between the tubes and the roof material surrounding the tubes; and which provides restraint against sidewise motion of the tubes caused by thermal expansion of the header in order to maintain the small clearance space between the tubes and the roof material.

According to the present invention, the insulating roof is of multilayer construction, the intermediate layer being mineral wool and preferably a resilient mass of refractory monofilaments. The resilient wool layer surrounds the upright tubes extending therethrough, and comes into engagement with one or more collars secured in sealing relationship to the outer surface of each tube to establish a seal therewith. It is the function of the resilient wool layer, not only to provide insulating characteristics to the roof, but also to cooperate with the collars on the tubes in resisting the flow of fly ash along the tubes in the direction of the penthouse. It is a feature of this labyrinth and filter construction that unrestrained longitudinal expansion of the tubes relative to the roof is permitted because the compressible mass of insulating wool yieldingly resists the longitudinal movement of the collars.

In one form of the present invention, the resilient layer of wool-like refractory material is disposed between two rigid layers of castable refractory material. The castable refractory material has insulating properties; but, because of its brittleness, means are provided to prevent the upright tubes from moving sidewise and breaking the edges of the refractory as the header undergoes horizontal thermal expansion. According to the present invention, there is provided for each row of tubes a bar or brace having snugly fitting holes for the respective tubes, the holes being sized and positioned to permit relative slid- 3,277,871 Patented Oct. 11, 1966 ing movement of the tubes while maintaining a sealing relationship therewith. By securing the brace, as by welding, to the metal frame surrounding the roof, the tubes are prevented from moving laterally in any horizontal direction.

Another way of preventing lateral movement of the upright tubes is to install bars which fit snugly between neighboring rows of tubes, and securing the bars at their ends to the metal frame. The spaces between the bars and the tubes can be sealed at the top surface of the roof by means of plates having holes for snugly receiving the tubes, with the plates welded to the bars.

Drilled plates can be employed to prevent lateral movement of the tubes along the length of the tube row, and spacer bars between the tube rows can be employed to prevent lateral movement of the tubes at right angles to the longitudinal extent of the tube row. The bars and plates may also be disposed in the layer of mineral wool, beneath a sealing layer of castable refactory material.

Various other objects, features, and advantages of the invention will appear more fully from the detailed description which follows, taken in connection with the accompanying drawings forming a part of the present application, and in which:

FIG. 1 is a sectional elevational view of a forced-circulation, once-through vapor generating and superheating unit to which the invention has been applied,

FIG. 2 is a view, partly in section and partly in elevation, taken vertically through the roof of the unit of FIG. 1, showing one form of roof seal of the present invention in detail,

FIG. 3 is a horizontal sectional view, taken along line 33 of FIG. 2,

FIG. 4 is a view similar to FIG. 2, showing a modified form of the invention,

FIG. 5 is a horizontal sectional view, taken 55 of FIG. 4,

FIG. 6 is another view similar to FIG. 2, showing the invention in still another modified form, and

FIG. 7 is a horizontal sectional view, taken along line 7-7 of FIG. 6.

In the drawings, the invention has been applied to a top-supported, forced-flow, once-through vapor generating and superheating unit designed for the production of su erheated steam.

The illustrated unit includes wall structure defining a shell 10 with a furnace chamber 12 in the lower portion of the shell and a penthouse 14 in the upper portion of the shell. The furnace chamber 12 and the penthouse 14 are separated by a horizontally extending, insulating partition serving as the roof 16 of the furnace chamber. The furnace chamber 12 may have a gas outlet 18 at its upper end, opening to a horizontally extending gas pass 20 which, in turn, communicates at its rear end with the upper end of an upright gas passage 22. At the lower portion of the furnace chamber 12 is a fuel firing section consisting of horizontally extending cyclone type furnaces 24 which serve to burn fuel and to discharge high temperature gaseous products of combustion into the lower portion of the furnace chamber 12, while discharging separated ash residue and molten slag.

The gas pass 20 is occupied by a first stage secondary superheater 26, a reheater 28, and a second stage secondary superheater 30, arranged in series with respect to gas flow. The gas passage 22 is occupied by a primary superheater 32 and an economizer 34, also arranged in series with respect to gas flow.

The vapor generating and superheating unit may be top-supported by structural steel members from which the wall structure defining shell 10 is supported. The upper portions of the upright tubes 36 of the

secondary superheaters

26 and 30 pass through the roof 16 for securement along line to the

headers

38 and 40, and they are expansibly secured to the roof in sealing relation therewith to permit differential movement according to the present invention, as described hereinafter in detail.

Referring now to FIGS. 2 and 3 of the drawing, there is shown, immediately above the horizontal roof tubes 42, a box-like steel frame 44 which is open at the top to receive roof insulating material. The frame 44 comprises four angle irons 46 extending about the periphery of the frame 44 to close the sides thereof. The bottom of the frame 44 is closed by a plate 48 apertured to receive the upright superheater tubes 36 in a closely fitting relationship which permits differential movement of the tubes 36 in vertical direction.

The refractory roof 16 of FIGS. 2 and 3 comprises three layers of insulating material. The lower layer 54 is a eastable refractory material which is poured into the frame 44 in plastic condition and sets to form a hard, rigid mass. If poured with stilf consistency, the bottom plate 48 can be eliminated from the frame 44, and the material may be poured directly on top of the roof tubes 42 and the reinforcing wire mesh (not shown). The intermediate or second layer 56 is a resilient body of mineral wool comprising a loosely packed, noncrystalline, fibrous mass which may be made as monofilaments from molten Georgia kaolin or other refractory material according to the disclosure in US. Patent No. 2,467,889, issued April 19, 1949, in the names of Isaac Harter, Charles L. Norton, Jr., and Leonard D. Christie, Jr., and assigned to The Babcock & Wilcox Company. The third or upper layer 58 is similar to the lower layer 54, and it may be poured directly on top of the mineral wool layer 56. Thus, the mineral wool layer 56 is sandwiched between the two

layers

54 and 58 of rigid eastable refractory material.

Still referring to FIGS. 2 and 3, the upright tubes 36 are each provided with at least one annular member or collar 60 secured in sealing relationship thereto, as by welding the inner edge of the collar to the outer surface of the tube 36. The collars 60 can be installed before the tubes 36 are in position and connected to the headers, or the collars 60 may be made in two or more parts and later joined together and secured to their respective tubes 36. The collars 60 are preferably positioned in vertically staggered and horizontally overlapping relationship, as shown, when neighboring tubes 36 are closely spaced and the collars would otherwise interfere with each other.

According to the invention, the collars 60 are disposed in an upper portion of the refractory wool layer 56 which yields to the downward movement of the collars as the tubes 36 undergo thermal expansion, thus maintaining the sealing relationship with the collars 60 without forcibly resisting their downward movement, and thereby preventing the development of bending and compressive stresses in the tubes. The foregoing arrangement of FIGS. 2 and 3 permits differential movement of the tubes 36 relative to the roof 16 and, at the same time, provides a labyrinth and filter construction which minimizes the leakage of fly ash from the furnace chamber 12 to the penthouse 14.

A modified form of the invention is shown in FIGS 4 and 5, wherein like reference numerals are employed to designate parts which correspond to similar parts in the embodiment of FIGS. 2 and 3. In this embodiment of the invention there is a lower layer 54 of eastable refractory material, and an intermediate blanket or layer 56 of refractory wool material disposed in engagement with the collars 60 on the upright tubes 36. Instead of an upper layer 58 of refractory material, however, the roof 16 is sealed at the upper surface thereof by means of tube spacer members 62 and tube tie bars 64, both of which extend horizontally. The spacer members 62 are of heavy gauge metal with a rectangular cross section; and they fit snugly between neighboring upright tube rows to thereby maintain their spacing and secure them against movement in one horizontal direction. The spacer members 62 may be installed by laying them horizontally on top of the wool layer 56 to compress the loose wool and pack it around the tubes 36, after which the ends of the spacer members 62 may be secured to the frame 44, as by welding.

There is a tie bar 64 for each tube row extending horizontally along the series of tubes 36 in the row and having holes for slidably receiving the respective tubes 36. The tie bars 64 are lowered until they come to rest on the spacer members 62. Preferably, the long sides of each tie bar 64 are welded to the upper surfaces of subjacent spacer members 62 and the end portions thereof are Welded to the metal frame 44. This arrangement provides another roof seal which minimizes the leakage of fly ash into the penthouse 14, and yet permits longitudinal movement of the superheater tubes 36 relative thereto.

In the arrangement of FIGS. 2 and 3, the tie bars 64 hold the tubes 36 against horizontal movement relative to one another longitudinally of the tube row; whereas the spacer members 62 secure the tubes 36 against movement in a horizontal direction at right angles to the longitudinal extent of the tube row. By preventing transverse or sidewise movement of the tubes 36, such as during horizontal thermal expansion of the

headers

38 and 40, the brittle refractory material in the lower layer 54 is protected against breakage around the hole edges, with the result that the clearance space between the tubes 36 and the refractory roof 16 is maintained and leakage of fly ash is minimized.

Still another form of the invention is shown in FIGS. 6 and 7, wherein like reference numerals are again employed to designate parts which correspond to similar parts of the previously described embodiments of the invention. An intermediate layer 56 of refractory wool material is disposed between upper and

lower layers

58 and 54 of eastable refractory material. The upright tubes 36 are provided with collars 60 disposed in the lower layer 54 of eastable refractory material, quite unlike the previous embodiments wherein the collars 60 are disposed in the resilient intermediate layer 56. In order to provide the clearance which permits differential longitudinal movement of the upright tubes 36, the tubes 36 may be moved up and down forcibly as the eastable material is setting, or heat may be alternately applied and removed to alternately elongate and shorten the tubes 36 while the lower layer 54 is in plastic condition, with the result that the collars 60 moving therewith establish for themselves voids 66 which provide the requisite vertical clearances in the lower layer 54. The same clearances prevail after the lower layer 54 has set into a rigid mass, and the differential movement of the tubes 36 and the collars 60 takes place without appreciable opposition during operation of the apparatus.

In the roof construction of FIGS. 6 and 7, tie bars 64 hold the tubes 36 in row against transverse movement along the length of the tube row, and spacer members 62 between tube rows hold the tubes 36 against transverse movement at right angles to the longitudinal extent of the tube row. The spacer members 62 and the tie bars 64 may be rested on the resilient wool layer 56 so as to compress the wool layer 56 with weight. Next, the upper layer 58 of eastable refractory material may be poured over the spacer members 62 and tie bars 64 to seal the roof 16. The tie bars 64 in the intermediate layer 56 assist the collars 60 in the lower layer 54 in preventing fiy ash from flowing along the length of the tubes 36; the tie bars 64 secure the tubes 36 in a tube row against horizontal movement in one direction; and yet the tubes 36 are free to move vertically relative to the roof 16.

Although the invention has been shown in but several forms, it will be obvious to those skilled in the art that it is not so limited, but it is susceptible of various changes and modifications without departing from the spirit thereof as set forth in the following claims.

What is claimed is:

1. In vapor generating and superheating apparatus, the

combination of wall structure defining a shell having upper and lower compartments and including an internal horizontal partition between said upper and lower compartments,

said lower compartment including a furnace chamber,

a plurality of superheater headers disposed in said upper compartment,

a plurality of rows of upright tubes, each extending through said partition into said upper compartment and connected to at least one of said headers,

said partition including:

a plurality of horizontally extending, fluid-conducting tubes arranged closely spaced in a row at the bottom of said partition,

a plurality of horizontally extending, elongated metal members joined to one another along adjacent longitudinal edge portions to form a fluidtight top surface of said partition, with at least some of the elongated members having a longitudinal series of holes slidably receiving respective upright tubes to hold said tubes in row and against transverse movement,

and a body of insulating refractory material between said horizontal tubes and the top of said partition including a layer of castable refractory material poured in place so as to rest upon said horizontal tubes and be supported thereby.

2. In apparatus according to claim 1, the combination as set forth wherein the body of insulating material in said partition further includes a compressible layer of resilient wool material above said layer of castable material, and including an annularly disposed collar on each of said upright tubes engaging said compressible layer.

3. In apparatus according to claim 1, the combination as set forth including a metal frame extending about the periphery of said partition, and wherein said elongated members are of rigid construction and each secured at opposite ends thereof to said frame.

References Cited by the Examiner UNITED STATES PATENTS 1,855,745 4/1932 Keenan 122- 235 2,337,208 12/1943 Reintjes 122-235 2,869,518 1/1959 Seidl et al. 122-478 3,062,197 11/1962 Fleischer 122510 3,181,508 4/1965 Hennipman 122-356 KENNETH W. SPRAGUE, Primary Examiner.

Claims

1. IN VAPOR GENERATING AND SUPERHEATING APPARATUS, THE COMBINATION OF: WALL STRUCTURE DEFINING A SHELL HAVING UPPER AND LOWER COMPARTMENT AND INCLUDING AN INTERNAL HORIZONTAL PARTITION BETWEEN SAID UPPER AND LOWER COMPARTMENTS, SAID LOWER COMPARTMENT INCLUDING A FURNACE CHAMBER, A PLURALITY OF SUPERHEATER HEADERS DISPOSED IN SAID UPPER COMPARTMENT, A PLURALITY OF ROWS OF UPRIGHT TUBES, EACH EXTENDING THROUGH SAID PARTITION INTO SAID UPPER COMPARTMENT AND CONNECTED TO AT LEAST ONE OF SAID HEADERS, SAID PARTITION INCLUDING: A PLURALITY OF HORIZONTALLY EXTENDING, FLUID-CONDUCTING TUBES ARRANGED CLOSELY SPACED IN A ROW AT THE BOTTOM OF SAID PARTITION, A PLURALITY OF HORIZONTALLY EXTENDING, ELONGATED METAL MEMBERS JOINED TO ONE ANOTHER ALONG ADJACENT LONGITUDINAL EDGE PORTIONS TO FORM A FLUIDTIGHT TOP SURFACE OF SAID PARTITION, WITH AT LEAST SOME OF THE ELONGATED MEMBERS HAVING A LONGITUDINAL SERIES OF HOLES SLIDABLY RECEIVING REPSECTIVE UPRIGHT TUBES TO HOLD SAID TUBES IN ROW AND AGAINST TRANSVERSE MOVEMENT, AND A BODY OF INSULATING REFRACTORY MATERIAL BETWEEN SAID HORIZONTAL TUBES AND THE TOP OF SAID PARTITION INCLUDING A LAYER OF CASTABLE REFRACTORY MATERIAL POURED IN PLACE SO AS TO REST UPON SAID HORIZONTAL TUBES AND BE SUPPORTED THEREBY.