US1636960A - Water-tube boiler - Google Patents

Description

July 26, 192?.

. WED. HOXIE WfXTER TUBE BOI'LER Filed Deo. 20, 1920 2 Sheets-Sheet l Jul 26-1'27; v ,1636960 y ",9* w.D.Hox|E WATER. TUBE B OILER Filed Dec. 250, 1920 2 sheets-sheet g E L INVENTOR ATTORNEYS Patented July 26, 1927.

`Ull'fll) STATES PATENT aerien',

VJ'ILLIAM D. HOXIE, OF WESTERLY, RHOE ISLAND, ASSIGNO'R TO THE BACOCK & WILCOX COMPANY, OE BAYONNE, NEW' ERSY, A CRPORATION OF NEW JERSEY.

WATER-TUBE BOILER.

Application filed December 20, 1920. Serial No. 431,975.

My inrention relates to water tube boilers, particularly of the type adapted for marine use.

@ne of the objects of my invention is to produce a boiler which will be compact in form and eflicient in operation. Another object of my invention is to provide a boiler which will have a minimum tendency to' form scale if the feed water for the boiler is impure.

TWith these and other objects in view, my invention consists in the constructions hereinafter described and specically pointed ont in thel appended claims. Y

In the accompanying drawings, Figure 1 is a front elevation, partly in section, of an illustrative form of boiler to which my present invention has been applied; Fig. 2 is a side elevation of the illustrative boiler with parts of the outer wall broken away; Fig. 3 is an enlarged view of a portion of the boiler in section to better illustrate the arrangement of some of the parts; Fig, 4 is a partial sec-tional view in the direction of the arrows l, el of Fig. 3, and Fig. 5 is a plan view of a part of Fig. 3.

Similar reference numerals indicate' similar parts in the several views.

ln modern marine boiler practice, it is frequently desirable to provide superheated steam. lt is also desirable that such superheated steam may be provided eiiioien-tly without seriously departing fr'om the type of boilers which have' come into common use for marine work. It is also desirable to design such boilers so that, so far as possible, the heat of the furnace will not be wasted by passing into the boiler room to the discomfort of the operators. The boiler of the present invention is designed to accomplish these purposes. y

In the illustrative form of boiler, 1()v is an upper water drum and 11 and 12 lower' water drums, the latter being spaced apart to accommodate a furnace chamber between them, this furnace chamber being of any desired form and, in the instance illustrated.I being adapted 4for oil fuel, the oil being introduced through burners p'rojected through theA openings in the furnace shown in the drawings. Each of the drums 11 and 12 are connected with the upper drum by a set of water tubes 12', 13. For' reasons which will bev explained more fully hereinafter, in the form of boiler illustrated, the upper drum 10 is provided with water com partments 14, 15, which, as shown' best in Figure 2, are preferably located centrally crosswise of the boiler and are much shorter than the length of the drum 10. rlhe drums 11 and 1,2 are also provided with compartments 16, 17 which entend the entire lengthV of the lowerwater drums. The two rearmost rows of tubes 18, 19 are divided into three groups of tubes, the tubes of the central group connecting` the compartment 15 with the compartment 17 on one side of the boiler, anda similaigroup of the set 12 connecting the compartment 1a with the compartment 16. The remainder of the tubes of the rows 1S, 19, which come in front and at the rcar of the compartment 15, connect the Acompartments 16 and 17, respectively, lwith the drum' 10, this being accomplished kby the fact that the compartments 14; and 15 are shorter than the length of the drum 10. l

A feed water' supplypipe 20 communi- Cates through the branchesl 21, 22 with the compartments 14 and 15, respectively. The

feed water enters these compartments and passes do-wn the central tubes of the vrows 1S and 19 to the compartments 16 and 17, respectively, and from thence through the remainder of the tubes of these rows into the main circulation of the boiler by way of the drum 10.

At the upper portion of each set' of water tubes and on the side away from the furnace chamber is a super-heater chamber which I have designated generally as 23, 24E. Each chamber is closed on its outer side and is open on the side adjacent the set of water tubes. ln each chamber is a superheater which, in the form illustrated, is composed ofheazders 25, 26 of the usual type, the inlet headers 26 being connected through the pipes 2T with the saturated steam outlet 28. The superheater tubes, which areillustrated as of the U-shaped type, entend from the headers 25, 2G in the usual manner land lie' crosswise of the sets of tubes 12', 13 in the chan'ibers 23, 24. n i When the U-sha'ped superheater tubes illustrated are used, I preferably sustain the weight of thel superheater tubes and mamtain them in definite relation with the water tubes by providing a support 29 extending upwardly from the lower drum beneath the superheater headers, the support 29 resting on the lower drum. At the opposite or free end, the U-tubes are supported by a kind of rack 30 provided with a number of tongues adapted to extend beneath the superheater tubes, this rack being attached to the rearmost row of water tubes by the clamping hooks 31, the upper end of this rack being also fastened to the upper water drum l() by means of the strap connection 32. The form of support shown permits a certain amount of relative motion in the superheater tubes, while at the same time maintaining them in a substantially fixed relation with the set of water tubes with which they cooperate.

A baille 33 extends from the lower water drum upwardly along the set of water tubes and, in the form shown. behind the second row of such tubes from the furnace chamber. The tops of the baffles 33 are removed from the upper drum lO a sufficient distance to permit the gases from the furnace chamber to flow up along the balile 33 and then enter among the water tubes at substantially right angles thereto. At the upper ends of the baffles 33 are provided cross baffles 34- which extend substantially across the set of water tubes and therefore to the open side of the superheater chamber. At the lower end of each superheater chamber is preferably provided a second cross baille 35 which is short enough to permit the gases to pass between its low-er end and the baffle 33. The parts are also proportioned so that the gases may pass between the baflie 35 and the corre` spending lower water drum.

Outside of the superheater chamber and the portions of thewater tubes below such chambers, extend side walls 36, 37 which are removed from the superheater chamber and the tubes a suflicient distance to provide a gas passage upwardly to the usual gas outlet. The walls 36 and 37 may insulated in the usual manner to prevent the passage of heat.

rlhe furnace gases rise along the baffles 33 and then divide with a portion passing into each of the sets of water tubes l2 and 13, in each of which the gases first pass across the water tubes at their upper ends and then flow over the superheater tubes in a genera'lly downward direction into the second pass between the baffles 34, 35 and from thence again across the tubes into the gas passage adjacentV the side walls 36, 37 to the gas outlet.

It will be seen that, by provi ding the baiiie 34, as shown, the gases are forced to flow entirely over the Superheater tubes after` the gases have passed across the upper part of the water tubes, and that the circulation to and from the water tubes and around the superheater tubes is positive and definite, so

that the operating conditions will not fluctuate unduly under different conditions of service. By interposing the superheater lwith its chamber between the water tubes and the gas outlet, a minimum amount of heat that might be absorbed in generating the superheated steam is permittedl to escape into the fire room through the side walls. as the spent gases serve to assist in insulating the boiler and superheater against such a loss. The sides are in reality jacleted with the spent gases, which serve more effectively to prevent such a radiation loss than the non-conductive covering and casing ordinarily employed.

If desired, the baffle 35 may be omitted, and it will also be understood that the bafiie 33 may be placed either entirely in front of the set lof water tubes or behind as many as is found desirable. lhile it is desirable. for well known reasons, to provide a boiler with a double set of water tubes as illus trated, it will be understood that certain parts of my invention may be applied to a boiler having one lower water drum only and one set of tubes. A double boiler of the type illustrated is desirable, however, because by providing a set of water tubes and a superheater on either side of the furnace chamber, a minimum amount of heat is per mitted to escape into the boiler room. Suitable dust doors and dust blowers may be provided in the several passes, as shown, te free the tubes from dust. y

I provide the upper and lower water compartments with the arrangement of the water tubes connecting these compartments, hereinbefore described, in order to purify the feed water as much as possible before the feed water enters the general circulation of the boiler. lt is well known that water containing certain impurities in particular' will have such impurities precipitated by heating the water to a relatively high temperature. Such precipitation in itself, however, is of no advantage unless the precipitates have an opportunity to settle down and thus become separated from the water. The best results will be obtained by first heating the feed water as rapidly as possible in its journey from the feed water inlet into the general water circulation, so as to cause itto reach a temperature sufficiently high to cause precipitation at the beginning of this journey, and then allowing the water to travel over a relatively long path arranged so that the precipitates may separate out, -and in which the temperature of the water 1s being gradually raised but so as not to boil, and thus agitate the water until the precipitates have had an opportunity to settle out. The arrangement of the water tubes connectting the compartments is particularly adapted to accomplish these ends. As the feed water passes from an upper compartment,

as l5, it crosses the first pass, .at which time the gases are still very hot, since they have been cooled only by crossing t-he upper part of the water tubes once; In crossing this first pass, therefore, the relatively cold feed water is raised very quickly to a. temperature suiiiciently high to cause precipitation. In the next portion of its journey downward, this water passes across the second pass in which the gases are considerably cooler' than in the first pass by reason of their previous passage over the superheater tubes. In the passage of this water across the third pass, it is contacted with the relatively cool gases which are passing' to the gas outlet. In the lower water compartment, the water turns and flows substantially horizontally, and from thence upward through the remaining tubes of the rows 18 and 19. In these rows, the temperature of the water is .gradually raised by reason of its passage across progressively hotter gas passages. It will be noted, therefore, that the feed water is first heated to a high temperature and that, in its continued travel downward and thence upward, additional heat is supplied in such a way that the temperature of the water is raised relatively slowly, and that, by reason of the direction of flow of the water, and

particularly its spreading out in the lower compartment, the precipitates have full opportunity to settle out without being dis-V turbed by the ebullition of boiling water.

For some purposes, some of the same results might be obtained by having the upper compartment connect with a lower compartment by a row of tubes extending entirely across the boiler, as the row 19, Vwith the lower compartment connecting with the drum through the entire row 18 of the tubes. Such an arrangement, however, would permit atleast soine of the water iiowing downward through the tubes 19 to return immediately through the tubes 18 without remaining for any time in the compartment 16 or l?, and thus not be subjected to the settling action which results when the water necessarily travels horizontally in that chamber as it does with the arrangement which I have illustrated.

Blow-off cocks are provided both for the lower water compartments and the lower water drums, such blow-off cocks being particularly desirable on the lower water compart-ments in order to remove the precipitates which may be thrown down and carried into those compartments from the feed water.

lWhile, preferably, I form the upper and lower water compartments directly in the upper and lower water drums, respectively, it will be understood that such compartments may be formed independently of these drums.

It will also be understood that any suitable type of superheater, other than the U-shaped one illustrated, may be used.

I claim:

l. A steam boiler comprising an upper drum having a compartment therein and shorter than the length of the drumy and smaller incross-section than lthe cross-sec tion of the drum, a lower drum having a compartment therein extending longitudinally of the drum for substantially the full length thereof and smaller in cross-section than thel cross-section of the drum, a bank of water tubes arranged in rows -across the boiler, some of the tubes of one of thel rear rows of water tubes connecting said upper and lower compartments and the remaining tubes of said row connecting said lower compartment and the water space of the upper drum outside said upper compartment, a feed water inlet for said upper compartment, a furnace on one side of said bank of tubes, a superheater on the side of said bank opposite the furnace, said superheater having tubes longer than the length of said upper compartment and extending transversly across the water tubes, and baffling arranged to direct the furnace gasesinto and across the upper end of said bank, then across the superheater tubes and then again across the water tubes.

2. A steam boiler comprising an upper drum having a compartment at each side of the vertical center line thereof, each compartment being smaller in cross-section than the drum and shorter than the length of the drum, a pair of-lower drums, spaced apart, each having a compartment smaller in crosssection than the drum and extending longitudinally of the drum rfor substantially the full `length thereof, a bank of tubes between each lower drum andthe upper drum, with some of the tubes of a rear row of tubes in each bank connecting one of the upper compartments with the lower compartment in the associated lower drum and the remaining tubes of said row connecting the lower compartment with the water space of the upper drum outside said Vupper' compartments, a furnace comprising a chamber at least a portion of which `is located between said lower drums and said banks of water tubes, aV

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