US1732428A - Steam generator - Google Patents

Description

Oct. 22, 1929. J. E. BE LL 1,732,423

" STEAM GENERATOR ,Filed July 22. 1922- 5 Sheets-Sheet 1 uvwmm/e By wee 6 1W 5 /MM A TTORNEY Oct. 22, 1929. J. E. BELL STEAM GENERATOR Filed July 22. 1922 5 Sheets-Sheet 2 "Um n INVENTOR I. J fl, L i 1 i M I l I I l I A TTORTNE xi Oct. 22, 1929. J. E. BELL STEAM GENERATOR Filed July 22. 1922 5 h ts- 11861? 4 INVEA 'TUR ATTORNEY J. E. BELL 1,732,428

STEAM GENERATOR Filed July 22. 1922 ,5 Sheets-Sheet s M a BY ATTORNE Patented that. 22, 1929 JOHN Ill. BELL, OF NEW YORK, N. "1., ASEJZGNOB TO FOSTER WHEELER CORPORATION, OF NEW YORK, N. 1., AOOHPORATION OF NEW YORK STEAM enunueron Application filed July 2.,

about 600 horse power nominal capacity, and

to be used in generating steam at a pressure of 1000 pounce per square inch; but my l:l-- vention may be employed in units of both larger and smaller capacity than that given 5 by way of example, and in generating steam at pressures both higher and lower than 1000 pounds; and, indeed, comprises features which may advantageously be employed in plants for generating steam at such ordinary commercial pressures as 200 to 300 pounds per square inch. V

lv'ly novel steam generator proper dillers primarily from an ordinary water tube boiler in that l connect the water tubes of my gener- 53 ator through suitable headers to vertically disposed steai'u and water drums which are of small diameter and are vertically elongated to provide water storage capacity, and the necessary steau'i and water separation I73 space. The relatively large number of steam and water drums which I employ in each steam generator or boiler unit, are connected. both, below and above the water level, to herizontally disposed drums or headers also of 305 relatively small diameter. One of these hori zontal drums serves as the boiler steam drum, and another serves as the boiler mud drum, while others serve primarily as pressure and water level equalizers.

In the preferred construction, each of the steam and water drums is bifurcated at its lower end to provide two Water legs or tube headers, and the two water legs or water headers of each drum are connected by a series of looped tubes, with the two limbs of each looped tube oppositely inclined to the horizontal, so that the circulation is downward. from the steam and water drum proper through one water leg into the corresponding ends of the looped water tubes, and thence 1922. Serial No 576,820.

upward through the water tubes and the second water leg back into the steam and water crum proper. Preferably the upper water tubes are encased in corrugated tubular cast iron sections to increase the amount and effectiveness of the water tube heating surface, except in the lowermost portion of the bank of tubes, where the casings are advantageously omitted, thereby avoiding the excessively rapid generation of steam which would occur in these tubes if they were encased as are the upper boiler tubes.

Advantageously, I associate with the steam genera tor proper, an economizer in which the heating gases leaving the steam generator heat the boiler feed water, practically to, or oven above the boiler steam temperature, and in which the feed water is at, or somewhat above the boiler steam pressure. The economizor thus serves to augment the water storage capacity of the steam generator proper which preterably is much smaller than in ordinary water tube boilers of similar capacity. nrdvantageously also, I employ in connection with the eeonomizcr and the steam generator proper, a steam supcrheater of the type disclosed in my prior Patent No. 1,296,- 7339, granted March 11, 1919, which receives heat from the furnace chamber direct, so that all of the heat recovered from the heating gases entering the bank of water tubes, is absorbed by the water tubes and economizer.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and itorming a part of this specification. F or a better understanding of the invention, however, and its advantages, and specific ob 'jects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illus trated n'eterred embodiments of my invention.

Qt the drawings i Fig. 1 is a sectional elevation;

F 2 is a section on the line 2-2 on Fig. 1;

Fig. 3 is a partial section on the line 3-3 of Fig. 1.;

Fig. 4 is an elevation of one of the steam generating sections;

Fig. 5 is a view taken at right angles to Fig. 4 with parts broken away and in sec tion,

Fig. 6 is a rear elevation of a portion of the steam generator with parts broken away and in section;

F ig. 7 is a vertical section through one of the steam separators;

Fig. 8 is a section on'the line 88 of Fig. 7

Fig. 9 is an elevation illustrating a modification; and

Fig.7 10 is a partial section on the line In the particular embodiment of my in- -vention illustrated in Figs. 18 of the drawings, A represents a boiler furnace which is provided with a stoker grate B, and is of conventional design, except with respect to the superheater arrangement to which reference is hereinafter made. At the top of the furnace chamber is the steam generator proper, which'comprises a plurality of sections'orunits, each of which consists of a vertical steam and water drum C bifurcated at its lower end, and looped tubes D, each of which is connected at one end to one, and. at its other end to the second of the two water legs or'headers C and C formed by the bifurcated lower portion of the drum C. In the particular form-shown, the two limbs of each looped tube D are each in the form of a straight tube, and these separate tube limbs are connected at their ends remote from the headers B and B by boxlike return headers E.

As shown the various return headers E are spaced and supported by suitable metallic parts R strung on bolts R suspended from a boiler casing frame part lV. The various bolts R are connected at their lower encs by a spacing member R The return headers E are shielded from contact with the heating gases by a wall A of refractory cement or the like.

The headers C are longer than the headers C and the limb of each looped tube D connected to a header C is upwardly inclined away from the leg, whereas the limbs of the looped tubes connected to the heath ers- C are downwardly inclined from the latter. The upper tubesD are encased in corrugated cast-iron tubular sections (Z, similar to those employed on Foster superheater tubes, but the two lower looped tubes D of each unit, and the lower limbs of the next two looped tubes D are left bare.

The drums C are connected at their upper ends to a common steam drum G which is horizontally disposed, and the lower ends of the legs C of the various drums C are all connected to a bottom or mud drum H. H represents a valved blow-off connection to the mud drum H. Adjacent their upper drum J and well below the connections from.

the drums C to the equalizing drum 1.

Feed water is supplied to the steam gcnerating units proper through a feed water supply pipe K which, in the construction illustrated, is connected to one end of the equalizing drum J through a valve K, and is connected to the mud drum H through a valve K In the construction illustrated, the passage of feed water to the steam generating units through the pipe K is controlled in automatic response to the water level in the steam generating sections, by means of a regulating valve K and a feed water regulator L, which may be of any usual or suit able type, and is connected to the boiler steam space through the equalizing drum I and pipe L, and is connected to the mud drum H by a pipe L The boiler water column M and guage glass N are connected to the steam space of the boiler through the drum I and pipe L, and are connected to the mud drum I-I through the pipe M N and M represent blow-off connections from the lower ends of the water column M and guage glass N respectively. Ballles of any usual or suitable form may or may not be associated with the water tubes D as conditions make desirable. As shown, the limbs of the tubes D connected to the headers C are covered for a portion of their lengths by bafiies O and a baflle 0 extends over a portion of the top of the bank of tubes D.

After traversing the water tubes D the heating gases pass through the outlet A into an economizer P. The economizer 1 as shown, comprises two banks P and P of horizontally disposed tubes which are formed of steel, and are adapted to stand high pressure, and are encased in tubular cast-iron sections similar to the casing sections surrounding the upper water tubes. The heating gases pass upward through the inter-tube space of the bank P and thence downward through the inter-tube space of the bank P to the outlet P to the stack. T represents the water inlet header of the conomizer from which the water passes back and forth through the tubes in zig-zag fashion from the bottom of the bank P to the top of that bank, and thence through the header 1 into the tubes of the bank P flowing back and forth through those tubes in the last men tioned bank in zig-zag fashion from the top of the bank to the bottom of the bank whence the water issues into the header l? connected all) to the boiler feed water supply pipe K. The cconomizer construction illustrated, and mode of operation described embodies features of invention disclosed and claimed in my co-peiiding applications Serial No. 3362M, tiled Nov. 7 1 919, and Serial No. 572,166, filed July 1, i922, now Patents numbered 1,565,304: and 1,565,305, respectively but other econon'liier constructions may be used, and in some cases no economizer need be used. I consider it highly desirable, in general however, to employ an economizer in which the boiler may be heated to or above the boiler telnperature while at a pressure as high or higer than the boiler pressure, and which is of suitable capacity to provide a water storage place supplementing the relatively small water storage capacity of the steain generatingiinits proper.

All of the steam issuing from the steam drum G passes through the steam pipe G to the steam inlet header Q of the superheater. The latter comprises a series of pipes Q encased in metallic protecting encas'lng sect-ions if which form a lining for the back wall of the furnace chamber A.- The pipes Q1 which are vertically disposed, are connected at their lowerends to the superheater outlet header Q), WVith the described arraiigemeut the superheater receives heat from the furnace mainly by radiation, and does not absorb heat from the heating gases after the latter leave the furnace chamber proper.

As shown, a battle C is placed in each steam and water drum at the side of the latter at which the header C is located. This ballle extends part way across the drum and serves to break up and deflect the stream of steam and water flowing up through the drum from the header C and thus minimizes the amount of water carried out of the drum C with the steam into the steam drum G. a further protection against the passage of water with the steam intothe drum G, I advantageously provide eachdruln C with a suitable strainer or steam and water separator. In the preferred construction illustrated for this purpose, the strainer comprises an outer tubular shell S, the upper end of which fits in the nipple connecting the drum 0 to the steam drum G. The lower end of the shell S is closed by a disk S into which is threaded the upper end of a tube S The lower end of the latter is threaded into a casing T, shaped to provide a seat T bearing on the division wall between the upper ends of the headers C and C The part T is formed with a thoroughfare for Water running down through the pipe S which terminates in an outlet T 2 opening into the downflow header Q. As shown, a pipe T 3 is threaded into the outlet T and has its open lower end located some distance below the top of the header C. Located within the shell S and separated therefrom by an annular space, is a second shell SA provided with an outwardly extending flange at its upper end which rests on the upper end of the shell The lower end of the shell SA is closed by a disk S pro vided with an outlet opening into which is secured theuppcr end of a pipe S which is of smaller external diameter than the internal diameter of the pipe S and extends down in the latter for a suitable distance. The shell S and SA are mechanically secured together by means of bolts S connecting the end disk S to an internal bridge S", andv the bolts S passing througl'i the end disk S and connecting a bridge piece S engaging the upper side of disk S" to the bridge pie re S. The shells S and SA are each provided with distributed lateral ports S, but the ports S in the shell S are out of register with the ports S in the shell SA. In operation the Water passing with the steam into the space between the shells SA and S, through the ports S in the latter, is largely eliminated by contactwith the outer wall out the shell SA and drains from the bottom oi? the space between the shells into the pipe S and passes from the latter into the water leg or header C at a level well below the normal boiler "water level. Water passing into the shell. SA through the ports S drops out of the steam and drains fromthe bottom of the shell SA througli'the pipe S into the pipe S. The steam and water separator de scribed is highly ellective, and is obviously simple to construct, and may readily be relnoved and taken apart for cleaning or readjustn'l'cnt, if and when this becomes necessary.

My improved steam generator may be provided. with attachments and fittings commonly employed Wlill'l water tube boilers, such as safety valves X and soot blower pi pes Y; and the usual provisions may be made for flooding the superheater with water when the generator being started into operation.

In operation, a vigorous circulation is maintained downward through the water leg or header G into the looped tubes 1), thence upwardly through the inclined limbs of the tubes D into the header C and tl'ience through the latter up into the steam and water drum C proper. Notwithstanding the limited amount of steam and water disengaging surface in the various drums C, the water level and pressure equalizing connections to the drums 0 make it possible to maintain a relatively steady water level in the drums C by means of an ordinary regulator controlling the supply of teed water to the boiler when connected to the boiler as described.

A characteristic feature of my invention is the comparatively small CllEUfHQbQL of the steam and water drums and the equalizing drums, all of which may readily be made circular or approximately circular in cross-secill) tion, and are thus well adapted to withstand the high internal pressure whichmay be obtained by the use of the invention. The dc" sirability of providing steam generator units of ordinary power house capacity capable of supplying steam at a pressure substantially higher than those or inarily employed 'at present is now becoming recognized by engineers. It is well known thatthe efficiency of a steam power plant increases, in general, with the pressure at which the steam is generated, and with the superheat given to the steam. While the prime mover efliciency tends to increase more rapidly with an increase in superheat than with an increase in steam pressure, the extent to which the superheat may be increased is limited by the ability of the materials available for usein boilers, pipes, valves, and prime movers to withstand high temperatures; but with a steam generating plant constructed in accordance with the present invention, the available construction materials will permit of pressure very greatly in excess of those employed in present day power house practice. The increase in the pressure of the steam generated permits of a reductlon 1n the volume oi the steam gencrating apparatus proper, and this facilitates the use of a boiler and economizing housing efficieney insulated against heat radiation losses and sheathed with metal to preclude air leakage and thereby enhance the plant eili 'ciency. In operation at high steam pressure it is especially desirable, of course, that the boiler feed water should not contain scaleforming impurities.

.The relatively small diameter of the steam and water drums and equalizing drums makes the water storage capacity of the boiler relatively small, but this is desirable for operation at very high pressures, and with an econ" omizer arrangement as described, the economizer provides water storage capacity which may be efiectively utilized in case of sudden increases in load. The economizer is especially effective because of the relatively high temperatures of the heating gases which must leave the boiler proper, at a temperature appreciably above that of the steam generated.

In the modified form of my invention illust-rated in Figs. 8 and 9, there are two sets of drums C located at opposite sides of the boiler, each steam generating unit, in this form of my invention, comprises two drums G, one at each side of the boiler and water tubes DA each of which maybe a straight tube. The tubes DA of each unit are arranged in two sets, the tubes in one set being oppositely inclined to the tubes in the other set. The tubes DA of one set are each connected at one end to the leg C of one drum C, and have their opposite ends connected to the leg C of the other drum C of the unit; while the tubes of the second set are connected to the leg C of the first drum and to the other leg G of the other drum. In this form the feed water supply pipe may be connected by branches K to the two mud drums H, and the two equalizing drums J are shown as con" nected by pressure equalizing tubes DC. As shown the two steam outlet pipes G are connected to a common steam delivery pipe (1 running to the superheater, if the latter is employed.

In the construction shown in Figs. 9 and 10, as in that first described each steam generating unit may be cut out of the boiler for repair when necessary without destroying the operativeness of the boiler as a whole.

IVhile in accordance with the provisions of the statutes, I have illustrated and described the best forms of my invention now known to me, it will be apparent to those skilled in the art, that chan es may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claim, and that some features of my invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

A steam generator composed of sections each of which consists of a plurality of vertically disposed steam and water drums each bifurcated at its lower end and looped tubes each of which has one end connected to one bifurcation and has its other end connected to the second bifurcation of a corresponding one of said vertical drums, a water level and pressure equalizing drum connected to the vertical drums below the water level therein, and a pressure equalizing drum connected to the vertical drums above the water level therein, and water level regulating provisions connected to one of said equalizing drums, and, automatically responsive to the height of water level in said steam and water drums Signed at city of New York in the county of New York and State of New York this 21st day of July, A. D. 1922.

JOHN E. BELL.

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