US2166188A - Flash boiler - Google Patents

Description

July 18, 1939. c. s. TURNER FLASH BOILER Filed Aug. 29, 1955 3 Sheets-Sheet 1 Nhen INVENTOR. ilafles I5L zrn er C. S. TURNER FLASH BoILER Filed Aug. 29, 1955 3 Sheets-Sheet 3 INVENTOR. 6" r/Zlr' f Patented July 18, 1939 PATENT OFFICE- FLASH no'lLEn Charles S. Turner, Detroit, Mich.

Application Augustv 2 9,

12 Claims.

This invention relates to the controlled heating 'of fluids, and is of particular utility where the rate of heat transferenceto and the temperature of theheated fluid are desired to be held within close limits, -not only in their average values and nal result upon the fluid discharged at the outlet, but throughout all portions of .the apparatus.

An important object is the provision of such apparatus enablingthe quick yet closely regulatable transference of large quantities of heat to iluids having low specific heats, which iluids may also be of relatively volatile character, such as hydrocarbon oils, without danger of localized burning.

A further object is the provision of a fluid-regulated 'still or retortincorporating temperature regulating means having a large excess cooling capacity, and so arranged that the metal of which the entire assembly is formed maybe cooled very quickly, whereby special heat-resisting metals such ascertain chrome-steels may be employed whichmust be very quickly cooled from an elevated temperature in order to anneal them and prevent their acquiring a dangerous degree of ,brittleress. In' the construction of stills for the cracking of oil it has been found impractical to employ such heat-resisting steels because of the fact that the walls cannot be chilled rapidly enough 'when the still is shut down to prevent tempering the walls to undesiredhardness in the objectionable manner referred to, and an important object of the present invention accordingly residesv in the provision of an improved still or retort of the character indicated which can be fabricated of such special steels, and accordingly may be operated at higher` rates and temperatures, which further not vonly incorporates a novel and improved form'oi temperature-regulating means affording a previously unattainable degree and accuracy of control. and absolute safety-against localized burning, but enables chillingy the heat-exposed walls'of the assemblyso quickly, when'desired, as to enable annealing the metal even though it be of that type which requires almost instantaneous quenching toi soften. Another object is the provision' in conjunction with duid-regulatedheatingmeans of anovel and improved "xnethod of. transferring heat .from

one portion to' another of the apparatus to equal- 50. ize heat absorption and reduce the ratio of maximum' temperature-to rate oi' heat absorption, by circulating and utilizing the regulating nuid in a novel manner. i

Another object is the provision of improved heating means of the character indicated `in 1935, Serial No. 38,436

which the precise control ofl temperature and heat transference remarked upon may be achieved despite variances of output demand upon the heating apparatus, diierences of temperature of the iluid as it is initially supplied, and/or differ- 5 ences in the temperature of 'the regulating or cooling medium., l Another important object is the provision of an improved boiler wherein a uid level may be maintained at any desired point, and eiectively regulated with relation to and in order izo-maintain any desired temperature, despite wide differences in the output of and rate of ow through the apparatus, and wherein such fluid level may be carried at a relatively high point if desired, to enable heat absorption by the fluid throughout a large proportion of the active' surface of the apparatus, yet in which the level may be so quickly controlled iny response to variances of demand andoutput that the danger of ilooding portions of the apparatus located beyond the heating apparatus and intended to be kept dry, is effectively precluded. l

Anobject incident to that last set forth is the provision of apparatus capable of successfully functioning as a true ilash boiler, incorporating generating water tubes in which a reduced water level may be positively and accurately maintained at a point below their full evaporative capacity, without danger of complete ooding of the tubes or the discharge of water into the receiver or relceiving, apparatus, and wherein such level may be maintained' despite wide variations of the rate of o'w through and the demand upon the boiler. Efforts to perfect a true flash boiler whose output is capable of wide variation have met with failure from a practical standpoint heretofore vbecause no method of controlling the water level therein has been known which is not so sluggish as to be dangerous, since control of the water Ylevel must 40 be quick and sensitive enough in its response to ,provide eiective safeguard against iiooding or discharging water to the receiver. The overcoming. of the difficulties mentioned may be said toconstitute in brief a summary of the objects 45 voi', this'invention, which is intended to so interconnect the saturated steam, generating andsuperheating means as to make the superheating eiIect dependent upon the waterlevel in the saturated steam generating portions, and control the 5o water level in the latter in response to the output temperature offfsuperhe'ated steam, and further aims to`so accurately control the water level in this manner that no reservoir whatever need be locatedA in thefurnacc, and that output variations su as wide as those encountered in? the operati-on of vertical and horizontal sectional elevational views respectively of an oil cracking st ill incorporating the principles` of this invention;

Figure 3 is a detailed section taken substan tially on the line 2 3 of Figure 1 and looking in the direction of the arrows;

Figure, 4 is a detailed cross section taken substantially on the line 4-4 of Figure 3 and looking in the direction of the arrows;

Figure 5 is a diagrammatic elevational view of a flash boiler construction incorporating the present invention;

Figure 6 is a section taken substantially on the .line 6-8 of Figure 5 and looking in the di.V

rection ofthe arrows; and

Figure 'I is a view analogous to Figure 6, on a smaller scale, of a modification.

Referring now to the drawings, reference character Il designates the front or furnace chamber of a still or retort whose walls denne a double pass furnace, the front portion being indicated as heated by an oil burner diagrammatically shown as of the jet type, the nomic being repre- 35, sented at I2 and the burner'controllable as by means of fuel valve Il. lThe gases after traveling upward through the fron section and through the cross-over I4, pass do wardly through the back section i5, whence theydischarge through 'io the stack ls. Tne`backseotion inoorporatesa preheater in the form ofsimple tiers of ysinuously wound pipes il, arranged in series: To these the fluid desiredto be heated-in the illustrative instance crude oil-ls initially fed through the supply pipe 1I.

At its upper end the preheater discharges into connecting pipe 22, which delivers the oil there-- from to the fluid-water regulated front section connected in series therewith and also constiso tutlng in effect a single pipe throughout its en'- tire length. The walls of the component pipe of which the front section is formed. however, as shown best in Figure 4, are-constitutedbym smaller pipe 24 coiled in the form of a tight helix andhaving its convolutions' welded'together as atA 2l tof form and seal aconduit lhe conduit, which is generally designated 25, serves to conduct the oil delivered to its lower end by pipe 22 through the frontfurnace section in 00 which the major portion of theiheatln'g is effected, and may discharge the heated oil at the top, as through delivery pipe 2l. The assembly comprising the oohduit :l donned by the helicoi-V ly coiled pipe 24 is arranged to line the entire 65 wall'oi'thefurnace Il anddirectly absorb hegt from the bur-ner. In vthe construction illustrated the conduit 2l is for this purpose shown as closely coiled about the interior, thus forming the entire heat absorbing wall of the furnace.

The longer helical passage by the coiled pipe 24 constitutes a heat Mulatlng lackvet and-the'tempenture of theduid (ou) passing conduit 2i may be governed by the regulated introduction of a conor resulltins fluid into the encircling' conduit 24. The regulating fluid may comprise water, which is fed from supply pipes 28 coiled Vsimilarly to or one lying outside each turn of the out the entire length of the apparatus. A main 15 valve 42 is also provided in the Water supply main 43. 'Ihe regulating fluid circulates rapidly in the tube 24. If water is used it of course at once boils in such a still and circulates in the form of steam. In so repeatedlyv traveling from the 20 Vfront, heat-exposed face of the assembly to the back, the regulating fluid picks up heatk at the front and delivers it to the cooler rear walls and the oil at the back, after which it travelsV to the front, picks up more heat, and again carries it to 25 the back, thus equalizing the delivery 'of heat tothe oily over the entire surface of the assembly reducing the temperature of the hotter faces of the vtubes in proportion to the amount of delivered heat and final temperature, reducing the 30 danger of localized burning and enabling operating the still at higher average rates of -heat transference than has been safely possible .heretofore.

Thus when a fluid, such as oil, having a relatively I ow specificl heat is to be heated, localized burning may nevertheless be effectively prevented by complete control allowing maintenance of every portion of the heating apparatus at safe temperaturesy despite which a lmaximum temper- 40 ature and rate of heat delivery may be maintained considerably higher than was heretofore feasible. l

Since relativelyconstantilow conditions ordinarily prevail in such stills, only minor changes in the settings of valves I2 are required during op- 45- Aeration under the usual conditions. Due to the `safeguarding effect of the steam jacket provided l steels mentioned becomes desirable. Withmy improved arrangement there isy no danger of e111-l 55 brittlement -of such steels when it becomes necessary to shut down the still; ii'vthe following4 procedure is, followed: The burner is first lowered and the oil shut on and cleared from the still plunges 25. 111e burner isset at'such level as 0 will enable to metal to vbe held at the wanted temperature for annealing (ordinarily about 1650 F. for such steels). Main water valve 42 is closed to cut oi! the water supply at this time, and the individuai'oonroi viuves sz are opened muy. The 5 metal is .allowed to soak at the elevated tem'- perature as longas is required for the annealing operationordinarily merely long enough for it y to reach uniforin temperature. The burner is then shut down and the valve 42 opened to deliver 7 y the full ilow ofwat'er to jacket tubing 24the quick oooumi eireot oorresponing in its rapidity to quenching.h Any-steam Vgenerated during this as well asall generated during regular operation` gigiigrgoq through stoom pipo. oonnoctod io '(5 I A plurality of .such units may of course be ar-v ranged in parallel or in any other desired disposition between headers, as 54-48, constituting respectively water feeding and saturated steam olif--` take headers, to` which connections are made from each unit by pipe sections 55--56 welded in the endsof the helical conduit assemblies as at 51.

All headers and connecting pipes may lie outside the furnace or heating chamber, shown defined by walls 6|. 'I'he water supply may be delivered'to header 54 from water pipe 52, which incorporates a thermostatically regulatable throttle valve 53. From the receiver 48 saturated steam may be conducted through pipe 65 to the lower end of the coiled conduit 2.4', through which it rises and in which it is superheated. It is to be observed, however, that a great proportion of the superheating will occur above the Water level, in-

. dicated at 10, and a much smaller proportion below it, the amount of superheat, and accordingly the temperature of the discharged superheated steam-thus depends upon the water level. It will also be apparent that by virtue of this coordination the temperature of the superheated steam discharged by such an assemblyis `an index of the water level, which may thus be regulated (by the throttle valve 53) to maintain the level at any desired point. preferably accomplished automatically by means of the thermostatic valve-operating means 15, mounted directly in the output steam header and quickly responsive to changes of the temperature of the superheated steam, and connected to throttle valve 53 in such manner that in response to a use of output superheated steam temperature it increases the opening of the throttle valve to allow the level to rise'and reduce the superheating surface, while a fall of superheated steam temperature, such as is caused by undue reduction of the effective superheating surface, (rise of water level) results in reducing the valve opening to allow the water level to fall, byvirtue of the reduced ratio of water supply to rate of vaporization. f This compensates by raising the superheat temperature. Thus a balance is struck and maintained which so long as the burner or heat source is operating at constant temperature positively maintains a predetermined level. The functioning of this apparatus is moreover automatically responsive to changes in the amount of heat supplied by theA burner or other heat source. The effect of turning down the burner will, by reducing vshutting it oil', resultsin also shutting` ofi' the water supplyat 'the throttle valve, but a level of Such regulation is, as indicated,

water always remains in the portion of the tube assembly within the zone of heating.

As shown in Figure 7, it is not essential that the coiled superheating tube envelope the entire saturated steam generating passage, .and such yportion may extend down the tube assembly only` far enough to cover the area within which the water level is maintained, while yet providing the desired superheating surface. The coiled superheating conduit is in this embodiment designated 242. The saturated steam generating tube is partly formed by thesimple pipe 562, which connects the lower end of each such assembly to the water header 542, lor other Water supply source, shown as similarly controllable in response to 532. The parts may be so proportioned that the water level always remains within the area encircled by the tube-portion 242, and the other portions and principlesoi operation of the modified construction will be seen to be so analogous to those of the embodiment of Figures 5-6 as to need no* rede- Like portions have been given like vreference characters,with the addition of the scription.

distinguishing exponent "2 to each.l

While it will be apparent that the illustrated embodiments of the invention herein disclosed are Well calculated to adequately fulll thevobjects and advantages primarily stated, it is tovbe understood that the invention is susceptibleto variation, modification and change Within the spirit and scope of the subjoined claims.

What I claim is;

1. A flash boiler comprising in combination with a heating chamber having walls, Water supply and steam oitake means located outside said walls, saturated steam generating means comprising a tubular channel extending through said chamber, a throttle valve in said water supply means whereby a reduced Water level may be held in said saturated steam generating channel within said heating chamber, saturated steam collecting means connected'to an vupper end of said channel, superheating means connected to the outlet of said saturated steam collecting means and comprising a conduit coiled in the form of a tight helix about at least the portion of said channel-within which'said water level is held, and thermostatic operating means -for said throttle valve responsive Ito the temperature of steam superheated in said superheating meansv and arranged to reduce the inflow of` water to the saturated steam generating channel in response to a fall of temperature of the superheated steam, and to increase such inflow in response to a rise in temperature of the superheated steam, and to maintain the water level. despite 'such variation, in the upper portion of the saturated steam generating channel when the source of heat is functioning normally. f v

2. A flash boiler comprising in combination with a heatingv chamberand a"source of heat therewithin, water supply and steam offtake means located outside the chamber, a water drum `connected to said supply and also located outside said chamber, tubular saturated steam generating channel portions connected to said drum and extending through said chamber, superheating means connectedl to-the outlets of Vsaid generating channel portions and helically coiled about at least aportion of said channelportions and in intimate-heat conductive| relation therewith, means for throttling the supply of water to said channel portions to maintain a water level Within a portion thereof encircled by said superheating means, thermostatic controlling means for said throttling means responsive to the tempera.- ture of the steam emanating from said superheating means and arranged to reduce th\ iniiow of water to the saturated steam generating channels upon a fall of temperature of the suberheated steam temperature.

3. A flash boiler comprising in combination with a heating chamber and a source of heatjherewithin, water supply and steam oitake means located outside the chamber, tubular saturated steam generating means connected to said water supply means, exposed to the heat of said heating chamber and having 'walls composed at least partly of a coiled element defining a separate passageway coiled about said generating means, said coiled element constituting a superheater and having metallic walls integral with those of the generating means, throttling means for holding a water level in said saturated steam generating means, means for conducting steam from the sat- 'urated steam generating means to said coiled superheater element, and means for regulating the throttle means and so the water level in the saturatedY steam generating means in response to the temperature of the superheatedl steam.

4. A flash boiler comprising in combination with a. heating chamber and a source of heat, water supply and steam offtake means located outside the chamber., tubular saturated steam generating means connected to said water supply means. eXDOScd to the heat of' said heating chamber and having walls composed at least partly of a tube denining a separate superheater pasmge, said tube being coiled in the .form of a helix and metallicallyintegral with the walls of said saturated steam generating means, throt- -tling means for holding a water level in said tubular generatingmeanameans connecting the generating means .and the superheater tube, whereby saturated steam from the former may flow through and be superheated in the latter, and' means for 'regulating the throttling means and so the. water .level in .the generating means in response to the temperature of the superheated steam 5. A' man boiler as ser forth in oioim 4 in which at least a portion of the walls of 'the tubular-'saturated generating means are formed en;-

tirely by said superheater tube said tube -coiledV -seambetweenthelm 7. A flash boiler comprising integrated metallic portions defining a water receptacle in the form oi.Y a'. relatively short passage inclined froml the horizontal, for generating.l saturated steam, a

relatively much longer superheater passage coiled about the exterior of the receptacle and in heat exchange relation withA the interior thereof, means for controlling said throttling means in response to the temperature of the steam superheated'in the superheater passage. i

8. A fiashvboiler comprising integrated metallic portions defining'a Water receptacle in the form of a relatively short passage inclined from the horizontal, for generating saturated steam, a relatively much longer superheater passage tightly coiled about the exterior of the receptacle and in heat exchange relation with the interior thereof, -means for feeding water to said receptacle, thottling means for said Water feeding means, and means for controlling said throttling means in response to the temperature of the steam superheated in the superheater passage.

9. A flash boiler comprising integrated metallic portions defining a water receptacle in the form of a relatively short passage inclined from the horizontal, for generating saturated steam, a relatively much longer superheater passage coiled about the, exterior of the receptacle and in heat exchange relation with the interior'thereof, means for feeding water to said receptacle, throttling vmeans for said water feeding means, and means responsive to the temperature of the superheated steam for controlling said throttling means.

10. Means forheating fluids, comprising in Ycombination with a source of heat, a substantially helically coiled tubular jacketing element, continuous means sealing the space between the convolutions thereof to provide anindependent central direct passage therethrough, said element being exposed to direct radiation from said source of heat only upon one side, whereby a regulating fluid ow through said tubular element passes alternately and repeatedly from the exposed side tothe rear and vice versa, and may equalize the delivery of heat to all portions of another fluid within the central' passage by surrendering heat to the portion thereof within the same but nearer the rear.

l1. A flash boiler usable in conjunction with a sourceof heat and comprising a water receptacle portion for generating saturated steam and a relatively long superheater passage connected in series and integrated with said water receptacle portion kfor ready heat interchange therewith, said superheater'passage comprising a relatively long tube coiled about and forming the external wall of thereceptacle portion, means for feeding war to said receptacle portion, and throttling,

means for said water feeding means vregulable in response to changing characteristics of the steam emanating from the superheater passage to mainvtain svriable water ievei in said portion of the passage.

12. A flash' boiler as set forth in claim 11 in which the tube forming said superheater passage extends integrally from the exterior to the interior of said receptacle portion to provide direct;l metallic heat paths `therethrough.

4(marinas s.

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