US2416674A - Attemperator - Google Patents

Description

March 4, 1947. G BAILE 2,416,674

ATTEMPERATOR Filed June 2, 1943 5 Sheets-Sheet l INVENTOR.

Erz in 6' Bailey ATTORNEY March 4, 1947. E. G. BAILEY 2,416,674

ATTEMPERATOR Filed June 2, 1943- 5 Shasta-Sheet 2 Fig. 2

INVENTOR.

Erz/in GBai/ey ATTORNEY March E. G. BAILEY 2,416,674

Fig.3

INVENT OR.

March 4, 1947. BAlLEY 2,416,674

ATTEMPERATOR Filed June 2, 1943 5 Sheets-Sheet 5 I 36 Steam & Wafer Drum @W 52 /lif,emperafor 54 L20 90 superheafer 56 S r V 60' 6-8 60 2 III I 4 60" W P2 By Pass Valve Dawncomer 45 ,6 Water-(Supply INVENTOR.

BY E rvin G Bailey "524m ATTORNEY Patented Mar. 4, 1 947 UNITED STATES PATENT-OFFICE- ATTEMPERATOR Erwin G. Bailey, Easton, Pa., assignor to The Baboock & Wilcox Company, Bockleigh, N. 1.. a corporation of New Jersey Application June 2, 1943, Serial No. 489,337

', 2 Claims. (Ol. 251-221) highly superheated steam, it is common practice to provide the steam flow elements in the form of U-bent tubes having their ends expanded or otherwise tightly connected to a tube sheet which, because of the many tube hole perforations along with the pressures involved, must be thick. Such thick tube sheets when additionally subjected to high temperature differentials resulting from a flow of highly superheated steam across the face of the sheet at the inlet ends of the tubes, and,

the immersion of the opposite face to a comparativeiy low temperature medium, become highly stressed and various expedients have been suggested to avoid or relieve such stressed conditions. None of these has been wholly satisfactory.

My invention is particularly directed to a construction of the apparatus which permits an allwelded assembly and specifically avoids expanded joints and thick tube sheets subjected to high temperature differentials resulting from the direct contact of the highly superheated steam on one side and the direct contact of the cooling medium on the other side.

The attemperator of my invention involves an assembly of a plurality of heat exchange units arranged for parallel flow of steam therethrough, the quantity of steam being under the control of a single valve. Each of the heat exchange units comprise a double tube assembly of a central tubular member through which the superheated steam is directed, and an outer concentric tubular member which is sealed at its ends to the outer tube to form an annular chamber through which water of the boiler is permitted to circulate with its flow induced by the generation of vapor in the annular chamber.

My invention presents a double tube attemperator which not only eliminates the necessity for employing 9, thick tube sheet subject to superheated steam at a high temperature (of the order of 930 F.) on one side, and water existing at boiler pressure saturation temperature of the order of 590' F. on the other side, but it also 2 eliminates heavy flange joints sive and troublesome.

The double tube attemperator of my invention involves independent tubular elements of relatively small diameter. The tubular units of the illustrative attemperator are characterized by the fact that all of the connections between the tubular parts are welded. Thus, the difficulties arising from the use of expanded joints with thick tube sheets are eliminated.

The tubular elements of my attemperator being of relatively small diameter permit a walllike arrangement in which a plurality of the elements are disposed in a row adjacent a wall of the steam generator. This avoids an undesirable concentration of weight, and, in many instances, effects a considerable saving in the space requirements for the steam generator unit.

The invention will be described with reference to a preferred embodiment shown in the accompanyin'g drawings and other objects of the invention will appear as the description proceeds.

In the drawings: c

Fig. 1 is a view in the nature of a vertical sec-' tion illustrating a steam generating and superheatlng installation including an embodiment of the invention; I

Fig. 2 is a view showing the attemperator in which are expenindicated at 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a horizontal section on the lined-4 of I Fig. 4 is a vertical section through one of the heat exchange units of the attemperator;

Fig. 5 is a detailed view showing the U-bend construction of the attemperator unit on the vertical plane indicated by the line 5-5 of Fig. 4;

Fig. 6 is a transverse section on the line 8-8 of Fig. 5;

Fig. 7 is a detailed view illustrating the welded sealing ring construction employed between the inner and outer tubular elements of the attemperator units; and i Fig. 81s a diagrammatic view in the nature of'a flow diagram showing an arrangement of the attemperator with respect to the superheater sections which are associated w th the steam gencrating installation.

The illustrative attemperator is. shown in Fig.

operating pressure of 1450 p. s. i. being 590 F.)

The smaller U-tube of each unit has an upright inlet leg I9 receiving superheated steam from a header I2, its outlet I4 being connected to the outlet header I6.

The inner U-tube ofeach attemperato unit is substantially enclosed by an outer U-tube so as to form annular chambers I8 and 29 around I the inlet and outlet legs, respectively, of the inner U-tube.

Water is-supplied through an inlet 22 for each cooling chamber I8, 9. similar inlet 24 conducting water to the lower part of each annular chambe 29. f a

' The annular chambers I8 and 29- are connected at their upper ends by an enlarged return bend 39 from which water and whatever steam there may be generated in the annular chambers I8.

the annula chambers of the attemperator units fromthe header I19 connected to the downcomer 49.

The annular chambers are provided with a supply of water from the steam and water drum, and because of this, and in consequence of the venting off of the upper ends of these chambers to the steam and water drum, there is an active circulation with progressive vaporization of the water, th height of the unit being such .as to give an increased effective head.

Referring particularly to Fig. 8, steam flows from the steam space of the drum 38 through the tubes 48 to the inlet header 50 for the super- Figs. 1 and 3 of the drawings.

tor units are connected to the inlet and outlet not concentrated at one position, but is distrlb-'- uted throughout a line parallel to a wall of'the matically controlled from one or more character istics of the steam generating and superheating installation.

Preferably, steam from the attemperator uni and the bypass flows from the header I6 through the lines 64 to the inlet header 66 of'the second superheater section 68 which consists of a plurality of return bend coils and tubular sections extending across the path of the furnace gases of the steam generator. Each coil is connected at its outlet end toa header 19 from which the steam is conducted to. a point of use.

The attemperator steam inlet and outlet headers are of considerable length and they are disposed along and between wall 12 of the furnace chamber and the air heater I4, as indicated in The attemperaheaders at clqsely spaced positions, and they are disposed in wall-like arrangement as indicated in Fig. 2. Thus, the entire attemperator may be disposed in a narrow space alongside a component of the steam generator, so as'to add very little, if any, to the floor space requirements for the entire installation. Furthermore, this arrangement affords an advantage with reference to the support of the attemperator. The load is installation. Thus, the attemperator may be supported by a plurality of hangers 89 secured at their upper ends to a beam 82 of the steel work at the upper part of the installation.

Referring to Fig. 4 of the drawings, the unit inlet tube I0 has welded thereto at its upper end a tubular section 99 of somewhat thinner-wall construction and larger diameter.

- 90 is united at its upper end by circumferential heater section 52, which preferably consists of I return bend coils extending across a gas pass,

each coil being connected at its outlet end to a header 54 from which superheated steam passes through the lines 56 and 58 to the attemperator inlet header I2.

Between, and connecting the lines 56 and 58, is a bypass valve construction indicated generally by the reference character 69. This valve functions to permit varying amounts of superheated steam from the line 56 to be conducted through the bypass line 62 directly to a posi-.

tion beyond the attemperator. outlet header I6, thus bypassing the heat exchange units of the attemperator, with a portion of the steam flowing from header 54. The steam flowing from header I6 and the steam from the bypass mix in the pipe 64 leading to the inlet header 66 of superheater section 68. When the tempera-. ture of the steam passing tothe inlet header 66 exceeds a desired value the valve is so operated as to cause a :greater proportion of the superheated steam from the line 56 to pass to the line 58, and thence through the inlet header' I2 to the attemperator units. Conversely, should the final temperatur of the steam fall below a desired value, the bypass valve is so operated as to decrease the proportion of the-superheated steam passing through the line 58 and to proportionately increase the amount of the superheated steam passing through the bypass line 62. For-this mode of operation, the valve includes the elements (dampers) 60 and 60" fixed at right angles to each other upon the same valve weld 92 to a tubular return bend 94. Then the external tube 96, with the flexible metallic sealing 98 secured thereto by the weld I00, is slipped over the elements Illand 90, the former having 7 a sliding fit within the sealing ring 98.

The outer return bend construction 30 consists of elements united by such welds as indicated at .l94 and H16 in Fig. 5, and this construction is considerably enlarged at its mid-section so as to permit of the relative movements of the return bends 94 and 30 resulting from differential expansion or contraction due to the large temperature diiferential between the fluids-to which those over the united tubular elements I9 and 99 to a position such asthat indicated in Fig. 4 of the drawings, the element 30 may be turned so that it slips over the element 94 and its end portion IIIl brought into alignment with the upper end of theexterior tube 96. Then the weld H2 is made, and the inner return bend 94 is moved-outwardly of the return bend 39 so that the upper end of the tubular section I I4 may be brought into alignment with the free end of the return bend 94 at a position externally of the confines of the return bend 39 in order that the weld 6 may be formed. The tubular section I I4 is united to the inlet tube I4 by the weld I I8, before the weld I I6 is formed.

The external tubular section I26 has a sealing ring I22 welded internally thereof near its lower end, this construction being similar to that indicated in Fig. '7. The sealing ring closely fits the tubular element I4 so that the combined ele-' This section' vide a pressure seal between the innertubes I 6 elements 90, H4 and 94 is then moved to its proper, position within the outer U-tube construction, and the inner components of the sealing rings 98 and I22 are welded. to the tubular elements In and I4 as indicated at I30 in Fig. 7.

.The annular chambers I8 and 20 are then put under hydraulic pressure for test purposes, and after it has been determined that the welds, and more particularly, the sealing ring welds I00, I30, are satisfactory, the thermal temperature gradient tubes I32 and I34 are slipped over to tubu lar elements I4 and I0, respectively, the welds I40- I43 at the ends of these elements are then completed and the annular thermal gradient chambers I48 and I50 are put'under hydraulic test. This test completed, these chambers may be closed by the plugs at I 58 and I60.

The U-shaped sealing rings 98 and I22 proand I4 and the respective outer tubes 96 and I20 while permitting the radial expansion or contraction of the tubes with changes in temperature. The welds HI and I43 fix the inner and outer tubes together so that differential longi- 3o tudinal expansion and contraction of the tubes will be away from the position of the welds. The seal rings 98 and I22by their fiexure allow for whatever differential longitudinal movement may occur between the concentric tubes at the position of the rings.

The inner tubular sections 90'and I I4 of eac attemperator unit are held properly centered within the external tubes 96 and I20 by groups of radial studs I80 -I82, indicated in Figs. 5 and, 6 of the drawings.

The headers I2 and I6 are fabricated with stub tubes I62 and I64 welded thereto, and after these headers with their stub tubes are heat treated, the

lower ends I0 and I4 of the attemperator units are welded to the upper ends of the stub tubes I 62 and I64, this construction method avoiding undesirably high stresses in the header metal. e

The inlet ends 22 and 24 of the water supply lines leading from the header or conduit I10 are secured to the external tubes 96 and I20 of the units by the welds I12 and I14 and the outlet tubes 32 are connected to the upper ends of the return bends 30 by the welds I16.

The steam generating installation shown in Fig. 1 includes a furnace 300 fired by pulverized fuel burners 302. .The walls of the furnace in clude steam generating tubes 304 and 305mm nected into the fluid circulation system "of-the generator and suppliedwith water through the downcomers 40 and the submerged drum 42. The upper ends of these tubes are in communication with the steam and water drum 38.

Thefurnace gases pass from the furnace 300 into the secondary furnace chamber 3| 0, the walls 65 of which likewise include steam generating tubes connected into the circulation system ofthe boiler. Above the second furnace chamber 3I0 there-is a bank of steam generating tubes 312 over which the furnace gases pass before they contact with the superheater section 68. These steam generating tubes are connected at their lower ends to a header 3I4 and at their upper ends to a druin 3"; which is in communication with the main steam' and water drum 38 through the circulators 320.

Although the invention has been described with reference to the structural details of the preferred embodiment illustrated in the drawings, it is tobe appreciated that the invention is not to be considered as limited to all of the details thereof. The inventionmay, rather, involve various combinations of the structural features of the illustrative embodiment, within the scope of the subjoined claims.

I claim:

1. In an attemperator for high pressure steam;

- each of said constructions including an inverted inner U-tube one leg of .which constitutes an'inlet for high pressure superheated steam, the lower end of the other leg of the inner u-tube constituting a superheated steam outlet, an outer U'-tube presenting a. separate annular envelope for each inner tube, each outer tube enclosing an inner U-tube so as to provide a closed annular cooling chamber in each leg of the construction;

means conducting water to the lower part of each cooling chamber, and a steam and water outlet communicating with the upper ends of said chambers, the arrangement presenting two water flow paths for each steam flow path and the water entering the cooling chambers having a temperature materially less than that of the superheated steam.

2. In a heat exchanger, an inner inverted U- -tube construction, an outer inverted U-tube construction enclosing theinner construction and spaced therefrom to present therebetween an inverted U-shaped chamber annular in cross-section with the thickness of the annulus less than the diameter of the inner tube, means providing for the supply of fluid to the inner construction,

means connected to the lower ends of the legs of the outer U-tube. and the annular chamber and providing for the supply of cooling fluid ends of the legs of said'inner and outer construc tions to close on the annular chamber, the relative expansion or contraction of the legs of said constf uctions being provided for by the movement of the U-bend of the inner construction within construction. ERVIN G. BAILEY.

' REFERENCES CITED The following. references are of record in the the U-bend of the outer file of this patent: s

UNITED STATES. PATENTS Number Name Date 234,645, Allington Nov. 23, 1880 290,929 Rew Dec. 25, 1883 545,612 Renshaw Sept. 3, 1895 2,214,548 Chute Sept. 10, 1940 1,884,263 Rudorflf Oct. 25, 1932 1,964,060 Huet June 26, 1934 1,897,845 Hilgers Feb. 14,1933 1,853,662 Cooper Apr. 12, 1932 2,063,441 Kerr Dec. 8, 1936 2,133,991 Kerr Oct. 25, 1938 1,890,185 I Lucke Dec. 6, 1932 2,331,932 Rowand Oct. 19, 1943 i J FOREIGN PATENTS Number Country Date German Apr. 27, 1940

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