US1696892A - Semiflash boiler - Google Patents

Description

C. A. FRENCH ET AL SEMIFMSHBQILERl Filed Nov. ll. 1920 2 Sheets-Sheet l GQOGGOGOOG/ @@@GGGGGOG- Dec. 25, 1928. 1,696,892

C. A. FRENCH ET AL SEMIFLASH BOILER Filed Nov.11, 1920 2 sheets-sheet 2 -1 h Patented Dec. 25,1928.

` lli-uNfvlTE-n s'rpTizsl PATENT cuantas A. ERENCROE cmcneo, AND UsTAE w.' EN'es'rRoialr, or RIVERSIDE, '11.1.1- i Nors, AssIGNoRs To INTERNATIONAL HARVESTER .CQMPANY, A coRPoRA'rIoN or NEW JERSEY.'

i I u invention relates'tov steam boilers and The, sash ma y I used in the generation of steam for the operation of motor cars compriseegenerating and continuous zone which is divided into generthe boiler andthe rate of steaming. This has l,

superheating coils or tubes which are in direct conmu'nication'- so that thesteam passes l0` directly fromthe generating zonetothe super heating zonein fact, the two zones form one ating and superheat-ing .areas that are continuously 'changing in relative size with the variationsvin the demands for steam made on been found. very unsatisfactory, since the y superheating zone -will be the largest and the resultant .degree of superheat the greatest when the load` and demand for ysteam are \lightest, and conversely, "when the wload is.

greatest and a large degree of superheat is desired, the superheating areadecreases, with the result that wet steam will be delivered to the engine and in some instances slugs of water have been carried over with consequent injury to the engine.v i

`. ln such boilers the superlieater is iusually located in thel hottest part of the path of the gases from the `f rnace or burner, which resultsin burning the tubes ofl the (super-- heater when the boiler is steaming slowly,

and necessitates their renewal at frequent intervals. I' y The tubes or coils are.comrnonly secured by welding or `by'special joints to headers or tube `sheets exposed to the iame and -hot gases from the burner. -The expansion and con-,

traction at the .welds or joints causes leaki age which soon becomes excessive and greatly. reduces the efficiency ofthe boiler and is the cause ofA frequent lay-up for repairs.

,Another objectionto boilers ofthis character has been the, inability to prevent formation of scale in the vaporizing coils or tubes and the impossibility bf removing the 'scale Aafter it has been formed because of the small size of the tubes.

Having the above noted defectsA in mind, wehave invented a boiler' that'is free fromi all of these faults a'nd which has amongits many objects to provide a boiler having preheatingevaporating, and superheating zones Applicationled `November-11, 1920. Serial No. 428,271.

semi-flash' boilers commonly accompanying 'drawings Iin' whichof fixed heating surface ratio to the burner. .e

Another object'istofprovide a boiler in whichy water cannot Ienter the superheating zone .for coils, thereby absolutely preventing pruning. v i f -A further object is to provide a boiler in which therJ are no joints between tubes and headers-or tube i sheets exposedgto the hot gases: but only coils, so thatd expansion and contraction can have no harmful effect. l y f A- stillv further object ithe provision of a boiler having a high rate of circulation in the vaporirzing coils, thereby preventing the formation and deposit of scale. f

Yet another object is the provision-of a boiler having the evaporating zone wherein the greatest amount of heat must be absorbed to 'ge'neratethe steam located in the hottest part ofthe boiler. i

Other important objects are to providea and affixed water level in the evaporating coils or the quantity of Jwater supplied thereto; to pro-y vide a boiler in which the superheateris'v protected from the hottest gases from the lso burner; and, to provide a boiler` having means dependent on pressure conditions in vt e boiler and rate of utilizing'2 steam for controlling the amount of fuel supplied to the'y burner.

The above and other objects will be apparent to those skilled in the art andare attained in the embodiment ofour invention`\ hereinafterl described and illustrated'in the Fig. 1J is afsectional view of one form of our improved boiler, the control means for ,I

the burner being 'shown diagrammatically.

Fig. 2 1s a sectionalview of` a modifiedE form of our invention. the control means being omitted for the sake of clearness. f 7 l I Referring to Fig. 1, 3 indicates the boiler housing or casing having lits top closed `by a burner fl, which Jis hollow or cored out at' to provide a. vaporizing ,chamber for the fuel sprayed from the nozzle 7 vinto the vpasl sage 8 leading from lthe fan or blower 9. The vaporlzed -fuel and air pass from the chamber 6 'to the burner tubes 10, which are providedv with fine slots orperforations through which the vaporized fuel' and Y ing zones, the filler 11 serving as a spreader for the flame and causing the liot ses to pass around and through the coils. After'givlng up their heat to the coils, the wastev products Vof combustion are discharged through the flue 12. The passage of fuel through the noz- Zle 7 is controlled by a needle valve 13 and the air is controlled by a throttle valve il connected to the pressure operated regulators 15 and 16, as will presently be described.

ln the embodiment of ouil invention shown in lfigq'1 we employ ten coils of which the four lower coils 17 constitute the preheating zone, the three upper coils 18 the evaporat ing zone, and the three intermediate coils 19 t-he super-heater. lt will of course be understood that this number of coils is but illustrative of our invention and that both the total and relative numbers of coils in the differentl zones may be changed as desired.

Feed water from the condenser enters the lower coil through the pipe 20, passes npwardly through the successive coils 17 and is discharged through pipe 21 into `the storage drum 22. The pump 24 draws hot water from `the drum and discharges it under increased pxressure to the pipe 25 from which it passes into the lower coil 18 and is transformed into steam as it passes upward through the coils. The steam'leaves the coils 18 throughthe pipe 26 which discharges tan- `gentially into the drurn22 above the water level. The tangential discharge ofthe/steam into the drum causes centrifugal separation of any moisture that the steaml may contain so that'only dry saturated steam will enter the steam pipe 27 and the superheat-ing coils 19 to which it leads. Superheated steanil leaves the coils 19 through the pipe 28 and passes through the heat exchange element 29 provided with the'batles 30 which cause the steam to take a tortuous passage through the Monel'or copper slugs with which the heat exchanger is filled. The object of the heat exchange element is to equalize the siiper.- heatby absorbing anynexcess that the steam may contain `and later giving it up if the operating conditions of Athe boiler should ,cause the degree of superheat to fall below normal. The heat exchanger insures an even degree of superheat in the steam udelivered to the engine through the pipe 31. p

It isto be particularly noted that the passage of the hot gasesthrough the boiler is directly opposed to the direction of the passage of the water" and steam inMall o f the zones,` and thatthe hot gases iirst encounter the evaporating coils whereby far the great- -est amount of heat must be given up to convert the water ,into steann After passing Aoverthe evaporating coils, the hot gases, with their temperature diminished below the point Leeasea heat the steannJ'lFhe gases lthen", pass overthe pre-heatiug'coils 1T and after giving up heat to the water therein leavdthe boiler through the stack or flue l2 ata'conxparatively low temperature, which we have found in practice does not exceed 250 l".

Returuingto the fuel and air controlling means. the regulator is provided with adiaphragm 32, one side of which is subjected to boiler pressure in the drumV 22 through the connectingpipe 33. it rod 3l contacts with the other 'side offthe. disphragm and is connected to the needle valve '13 and throttle valve la by the links and levers illustrated. 'l`he boiler an/d drumaredesigned to operate under a normal pressure of 500 lbs. per square inch, and when this or a lower pressure exists in the drum 22, the valves-13 and 14 will be fully open, but as the pressure increases. the rod 3-1 will 'be actuated to reduce the valve openings and lat' 600 lbs. pressure per square inch both valves closed. 0 Y

The regulatbr 16 has andiaphragm 36, one

`side of which is connected to the intake side of the pump 24 by pipe 37 and the other/side' from the drum 22 and 4forces it through the vaporating coils at :thigh speed, the velocwill be fully ity of the water entering the roil being'approximately 500 feetV per minute, and that of the`steam leaving the coil and entering the drum being-12000 to 20,000 feet per mnnte; a ditferencedn pressure of 50 to 100 lbs. per square inch between the intake and discharge sides of the pump ybeing required to dothis. When the pump is receiving water 'from the drum this diderence in pressure exists on the two sides of the diaphragm 36 llO and the valves 13 and 121 are held open, but..

if the supply of water in the drum fails or the pump fails to feed water to the evaporating coils for anyreason, the pressure will be equalized on the two sides ofthe dla`` phragm and the valves 13 and 14 will be closed. V

It will thus be sen'tha-t we have-provided.

means for keeping the pressure substantially constant in our boiler under all loads since the valves 13`and 14 will ble partially vclosed by the Iincrease in steam pressure when the boiler is steaming slowly under a light demand for steam and correspondingly opened to generate moreisteam as the demand forJ steam 1ncreases, The regulator 16 srves as a safety device to prevent burning of the evaporating coils if the supply of water fails. `It is toibo' .noted that the water level in the drum 2 2 may vary from a maximunr at the' height of thepipe 26"to a minimum at the pump intake level `.without affecting the operation -or steaming qualities of the boiler. We consider this a. Very important part of'our invention,

since it Venables the boilerto operate under widely varying lads, without .changing the system.

` in) the location and type of burner; the a-r- The burner proper consists oftwo cylindrical rangement of coils, ankd'` housing ofthe storaged'rum, coils and burnerA within a single casing. F v

A blower and fuel pipe 51 co-operate to supply air and fuel to the vaporizing drum 52 of the burner, the mixture enteringthe drum tangent-ially so that centrifugal separation will keep the unvaporized fuel against the outer portion of thedrum and the heated and thoroughly vaporized -mixture atthe center.

. sections 5% and 54 which are in open communication wit the center of thel drum 52 at the tophnd bottom respectively. The side Walls of the sections are finely perfdrated and the mixture burns as it issues therefrom. Flame from the lower sectionslfpasses radially outward and then upwardsabout the ydrum 52, heating and Vaporizig the fuel mixture therein," The gases thcln passl,upward and mingle with the gases from the main burner section 53. i l' w A pilot burner 55 is used to initially heat the drum 52and receives its fuel under pressure from the coil 56. The coil 56 extends outside the burnercasing and has a starting coil 57 within a. heating cup 58, the coil then re-,enters the casing and discharges into the ejector 59 Where it picks up sufficient air to forni a combustible. mixture which enters the pilot. burner tangentially In starting the boiler, a quantity of Volatile fuel such asgasoline, is supplied to tliecup 58 suflicint to vaporize the fuel in theacoil 57. As this fuel becomes vaporizedl it enters the pilot burner mixed with air where it is ignited. lVhn Ythe drum 52 becomes heated, the vapor-ized mixture issuing from the burner sections 53 and 54 will-be ignited', the section 54' being ignited from the pilotl burner, anl tliesection 53 being ignited by flame following the perforations 60 inthe pipe 61 connecting the' sections'V 53 and -54-v on opposite'sides of the drum-*52.

The r-preheating, superheating and evaporating coils in Fig. 2 surround the burner' 53 -so that the path of thelhot gases is radiali outward through the coils instead of longi- -tudinal as rin Fig. 1. Specifically,y these coils comprise separate, horizontally or radially spaced, vertical b-anks of evaporator, super- `heater, and preheater coils, `each bank coniprising superposed, helical coils lying in sub-` with and sur-y down in the second coil and upward through .the third coil, thence to thestorage drum through pipey 66.4 The circulating pump67' draws water from the drum through' intake pipe 68 and dischargesfit underincreased pressure Ilirough pipe 69 and evaporating coils TQ; The evaporating zone consistsvof 'the` two inner banks of'cgils' 70 and a flat coil continuous therewith and bridging the annular space( between the burner` and inner k of Water is upwardin the outer coil, then Y' coils.' The steamgenerated in the coils 70 issues tangentially into the storage drum through the pipe -71 above the water line. Dry steam is taken from the top of the drum by the steam pipe 72 and after passing through the superheating coilsl 73 is led through pipe 7 4 to the engine or other prime mover. Thus, it isseen that the evaporator coils have water delivered totheni under in- `creased pressure, by the pump. 67 drawing water from the storage and separating drum 'v 65. This increased water supply increases the heat absorbing capacityJ of the V evaporatorcoils thereby to protect said coils and' also further to protect the superheater coils and to increase the rate of steam generation in said evaporator coils.

The waste gases afterpassing radially outward from the `burner'and around'tlie coils pass upwardinto annularH space 75 in the dome shaped chamber 76 through perforations or openings 76 near the periphery of the upper wallf2'7l of the casing 7 8 housing ther/coils and burner. The storage drum 65 is housed vwithin the` casing at this point so that it is surrounded by the waste gases which have a temperature considerably above Y that ofthe atmosphere and enclosed with-in the insulating lining 75. This enables us to reduce the radiation loss from the drinn. and also to use less heat insulatlon or lag-f ging thereon. The waste gases are finally discharged through-.the-stack 79.

W-have shown the superheater'coils of slightly greater diameter in Fig. `2, than lll() the tubes of the preheating-and evaporat-v pand in the superheating coils as its temperature increases wit-hout increasing its velocity land.also enables us t'use fewer coils in the Y ing coils, which we have found to be advan-A tageous in that itA permits'the steam yto ex- Fig. 2, but it is to be understood that they are adapted for use withthis form of boiler as well as that shown in Fie'. l and are omitted only to v avoid needless repetition and complications in the drawings. -`While we have shown the tubes of the preheating superheating and evaporating coils ot the same diameter in Fig. l, they may be of any relative diameters found necessary to secure the desired rate ot flow of fluid in the coils, rate of steaming' of the boiler and degree of superheat.

Having thus described our invention, what we claim as new and Adesire to secure by Letters Patent is: Y

l. lna steain generator, the combination of a burner, a casing, a superheater of fixed heating surface, an evaporator of fixed heate ing surface, a preheater of fixed heating` surface, the superheater, evaporator and preheater all surrounding the burner, a storage drum, means for supplying water to the preheater, a connection for discharging the water from the preheater into the drum, a single connection for taking the water from the drum and delivering it to the evaporator, a pump inl said single connection for forcing the water through the evaporator, a connection for delivering water and steam from the evaporator back to the drumabove the center thereof, and a connection :from thev top of the drum for "delivering the steam to the superheater. y

2. In a boiler, the combination of a casing, a burner discharging hot gases of cpmbustion thereinto, an evaporating coil adjacent the burner and having an inlet and an outlet, a superheating coil adjacent. the evaporating coil and having an inlet and outlet, the inlets of the-respective coils being at ai point most remote from the burner and the outlets being at a point nearest the burner` a receiverfto which the inlet and outlet ends of the evaporatingcoil and the inlet end of the superheating coil are connected, and means for forcing fluid through the evaporating coil. ,f

3. In a boiler, the combination ofa'burner,

an evaporating oil comprising a plurality of` concentric convolutions adjacent. the burner, a superheating coil comprisinga plurality of convolutions adjacent the evaporating coil, a preheating coil comprising a plurality of concentric convolutions adjacent the superheating coil, a housing for the burner and coils. adrum outside the housing, means for supplying fluid to the Preheat-ing coil at the point mostv remote from'the burner, a dis-v charge connection to the drum from thepoit ot' the preheating coil nearest. the burner, a 'conneetionbetween the drumandevaporating coil'atthe point farthest from the burn-\ er,`circulating means in the lastnamed connection, a connection from the end o't the evaporating coilnearest the burner diseharg;

ineaeea i outside ther-casing between the lower part of the drum and evaporator, a pump in said connection for forcing the water through the evaporator, a connection outsideI the casing from-the other end of the evaporator to the top part of the drum for returning a mixture of water and steam to the drum, and a connection outside the casing from the top of the drum A"to the superheater coils.

5. rlhe combination with means forming a combustion chamber having upper and lower gas confining means in f horizont-aly planes, of means for introdueinga combustible mixture into said combustion chamber through one ot' said planes substantially centrally of 'said planea-nd for directing the products of combustion in their travel to the t exit at the other plane to cause them to pass,

laterally through said chamber throughout substantially the entire extent between said two planes, a steam generator composed of tubes formed in coils which are vertically and horizont-ally spaced apart and surround a central-space and are located between and extend closely Iadjacent to the horizontal planes defining sai-d chamber so as to be confined within the maximum heating space of the gases i and between which coils thev gases pass, said tubes comprising evaporator, superheater, and preheater sets of distinct and fixed hea-ting area with the evaporator tubes interposed between the point of greatest heat intensity and the superheater tubesV toyprotect the latter, and means t0 establish communication'between the: successive sets ,of tubes.

lla

6.5 The combination with a burner having 4 an upright part having'lat'eral openings for the productsof combustion, of a boiler, said boiler comprising horizontallyy spaced, vertical banks ot separate evaporator, superheater and preheater tubes in coils, each bank including superposed tiers ofv coils vertically spaced,- and. said banks surrounding the burner part and lying in substantially the same Vhorizontal vconfines therewith, the

evaporator bank being nearest the burner part, and the snperheater coils located so as to have the evaporator coils between the superheater coils and the fire, and means receiving water Afrom the preheater coils to s'upply the evaporator coils.

7. The conibinatlon with `a burner dis- Lchar-ging not gases, of asteam generator comprising tubes yin coils against which the hot gases impinge and between which they pass, a non-evaporative storage and separating drum communicating with the coils, means to isolate the drum from the combustion chamber, and means through which the waste gases are conducted after they pass between the coils so located as to prevent direct con- ,4 tact of said gases with the drum and toinquantity to that received from the preheater to thereby increase the heat absorbing capacity of the evaporator coils and their protecting capacity for themselves and the superheater coils, said superheater coils having communication with the drum 'to receive steam therefrom, and conducting means for the hot stack gases surrounding the drum to thereby protect the latter from the cooling effect of the atmosphere.

9. The combination with a burner discharging gases horizontally therefrom, of a steam generator composed of separate, horif zontally spaced vertical banks of evaporator, superheater and preheater tubes in coils, each bank comprising superposed separated helical coils lying within horizontal confines with and surrounding the burner, the evaporator coils being between the burner and the super` heater tubes to protect the latter from the heat, a storage and separating drum storing'a quantity of water which is additional to that fed through the preheater tubes, said superheater tubes having communication \.with the drum to lead steam therefrom, said evaporator tubes having both outlet and inlet communication with said drum, means to conduct the water which has passed through the preheater tubes to the evaporator tubes and means to supply through the evaporator tubes a quantity of water from the drum additional to the quantity of water which has been fed from the preheater tubes to thereby increase the heat absorbing capacity of the evaporator tubes over that provided by the amount of water therein received from the preheater tubes, and also further to protect said superheater tubes by increasing said heat absorbing capacity, and to increase the rate of steam generation in said evaporator tubes.

, In testimony whereof we aix our signatures.

CHARLES Af FRENCH. GUSTAF W. ENGSTROM.

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