US1817419A - High pressure steam generator - Google Patents

Description

5 Shafts-Sheet 1 Aug. 4, 1931.

Figi.

Aug. 4, 1931. w. G. NQACK 1,817,419

HIGH PRESSURE STEAM GENERATOR Filed April 9, 1928 5 Sheets-Sheet 2 Fig.2. 43 411154??? N Aug. 4, 1931. w. G. NoAcK HIGH PRESSURE STEAM GENERATOR Aug. 4, 1931. w. 5, NoAcK HIGH PRESSURE STEAM GENERATOR Filed April 9. 1928 5 Sheets-Sheet 4 Aug. 4, 1931. w, G, NQACK 1,817,419

HIGH PRESSURE STEAM GENERATOR f 777W@ ff@ M.

Patented ug. 4, y1931 UNITED STATES ,PATENT OFFICE WALTER GUsTAV NoAcx, F BADEN, SWITZERLAND, YAssIeNoR To AKTIENGESELI; Y soHArT BROWN, BovERI a CIE., or KBADEN, SWITZERLAND HIGH PRESSURE STEAM GENERATOR Application filed April 9, 19278, Serial No. l268,493, and in Germany and Switzerland April l14, 1927,

It has yalready been .proposedto lgenerate steam by superheating steam and passing the ,superheated steam through a layer of water or. injecting finely divided water into .j 5 the same. Fresh steam is ,then generated by the transmission .of the heat .of superheat. It has further been'proposed topass superlieated steam several times through water .and to ysuperheat the steam freshly l1o generated .each timeand the previously generated Y steam *whichy has been cooled down by beingpassedl throughthe layer yof water, until finally the required quantity of working steam has been generated.

l For overcoming the resistance ,of the superheaters vand that of the load of water and to bring the steam `in-to circulation, various expediente are required which entail certain disadvantages. If, for instance, the steam be generated in a lsingle heat exchange body, it is necessary toprovde a separate pump for circulating the steam which acts as the heat carrier and for various reasons must be many times the ,quanltity of useful steam, whchpump requires a relatively large amount of kenergy `and vdetrimen-tally` affects the efiiciency of the plant toa considerable extent through the unavoidable leakage losses. If, on the other generating in a separate boiler so-called exciter steam at va higher pressure andby allowing the said exciter steam to fiow with its own 4drop lin pressure successively through several superheaters 'y and water spaces, .fresh steambeing generated in each `Water space by the heat of superheat, vthe hcirculating pump becomes superfluous, it. is

true, butv a larger number ofl pressure .con-V tainfers becomes necessary which. increase the cost of the plant, require more space and introduce certain working difficulties..`

- The present invention relates to a method.

.of producing steam, more particularly high y Quantity et .steam than half the .quanhand, motion be imparted to the steam by tity `of working steam) lis generated, which flows under its `own drop y in ressure through a lconsiderable number o super- :lieaters yor groups -ofsuperheaters located `one behind'the other', which are'prov'idedf at any number of points, but at least two points, -with devices, by means of .which water is introduced in a finely divided state. By withdrawing the superheat, fresh steam is generated `from the introduced water, which steam is superheated together with the now saturated,` previously generated steam and so on until the desired quantity ofworking steam 'is obtained. i Figure l shows diagrammaticaljly the arfjg, .rangement of the steam' generator according tothe invention.

Figure 2 is a diagrammatic; section through the evaporator and the steam and i water collector with the water injector '7b' pump. 4 Figure 3 shows the section throughr an evaporator with filling bodies for Vinc-reasing the water-surface. f f 7 Fig-ure 4 the saine with filling bodies to a'ct as water separators.

Figure 5' the arrangement of the evaporators witha device for injecting addition water, y

ythe steamgenerator with pump for the injection water and a' heat pump, through which the exciter steamv can be generated (instead of the exciter steam boiler). j

In Figl of theaccompanying drawings the steam generator is shoWndiagram-mati- .cally tor carrying outthe method. In this figure, l is the furnace space. In this space is the exciter boiler Qand 3 lin which thesmall quantity of exciter steam lis produced and the remainder of the feed water may j be preheated; l The vexciter steam Hows thence under its ,own pressure` through the pipes 6 by way of a throttling point 29 and a shutting off valve 33 to thefirst superlieater 7, `is highly -superheated in the said superheater and passes to thefirst evaporator 13, where the heat of superheat is with l.drawn trom it by injected water which has ,y

abeen preheated --almost upto evaporation Figure 6 diagrammaticalv arrangement ofso f esr telnperature. By this superheating heat fresh steam is generated from the injected water, which steam together with the exciter steam which has been cooled down to approximately saturation temperature flows to the next superheater 8. Fresh superheating heat is supplied to this superheater, which enables an increased quantity of steam to be generated in the next evaporator 14 from the Water'injected into the steam. This is repeated until finally the required quantity of working steam is obtained.

The water to be injected can, as already stated above, be withdrawn from the exciter boiler 2, 3 lying in the furnace space, which therefore in the present instance also acts as water heater, through the pipe 5 by way of a shut-off valve 32. The fresh water itself is introduced yat li. The whole of the steam generated leaves the last evaporator 18 by way of the valve 31 and passes through a final superheater 28, where it is brought up to the degree of superheat required for working purposes, to the `place where it is to be used. The other parts shown in Fig. l and not hitherto described will be alluded to later on.

While Fig. l shows diagrammatically the steam generator seen from above, Fig. 2 shows the evaporator part with the container diagrammatically in side elevation partly in section. 13 to 18 are the evaporators which receive their injection water Athrough the pipe 5 for instance from the water preheater of the exciter boiler (not seen in this Figure). The water is injected through nozzles i0 in a finely divided state, so that it offers a large surface to the superheated steam entering at 4l., At 42 wire sieves are vprovidedvwhich hold back large drops and cause them to be divided up and evaporated. The cooled an freshly generate steam leaves the evaporators at 43, whence it Hows to its particular superheater. In front of the outlet parallel sheet metal members may be provided, on which any witer which may be carried along separates o The object of injecting in a very finely divided state is, as already stated, to present large surfaces for making a rapid absorpv tion of heat possible. Instead of injecting in a finely divided state through nozzles the spreading of the water to be evaporated over a large surface may be effected for instance by `suitable iliing pieces provided in theevaporatingbodies. This expedient has the advantagethat in place of a nozzle of small bore ordinary roses can be used, which are `less liable to become stopped up, and thatthe carrying along of drops is more readily prevented. These filling piecesfmay consist` of small cylinders (so-called yRaschig-rings) Vand are made of a material which is ay very good heat conductor. In

Figs. 8 and 4t evaporators of this kind are shown in section. 50 is the body of the evaporator, 5l are filling pieces. They rest on a grid 52 below which the superheated steam is admitted at 58. The water enters through a rose 54; and is distributed over the filling pieces, whereby it presents a largersurface to the steam meeting it in counterflow. The cooled and freshly generated steam'flows off at 55 while superfluous water is drained at 56.

The constructional form shown in F 4; differs frornthat of Fig. 3 in this, that the filling forms two layers 5l and 57, having a free space between them, into which the rose 54 opens. Thus, only the lower part is played on, the upper part acting 'as a steam and water separator. In addition it may be heated by the admission of superheated steam' from the pipe 53 or 58, so that any adhering drops will be evaporated.

It is important that the steam generator nder discussion should always be operated in such a manner that the iinal temperature of the superheating in each separate superheater and the quantity of water injected bear a certain relation to one another. I/Vhen too little water is supplied, the consequence will be that the steam introduced is cooled off too little and will be superheated too strongly in the next superheater. Too much water on the other hand has the disadvantage that water may easily be carried along and any impurities may be deposited in the super-heater tubes, rendering the latter foul. Another disadvantage may be that unnecessary pumping worlr has to be performed. @ne possible manner ofA regulation is pro- `vided by the temperature of the superheated steam itself. For instance, a thermostat may be provided which is influenced by the temperature of the steam at any point, more particularly the temperature at the end of the super-heater following an injection nozzle orgroup of nozzles. In Fig. l the arrangement of such a method of regulation by a thermostat is shown. In this `ligure 19-23 represent thermcstats of any known constructional form which act on cut-oit devices of any kind for the water supply pipes of the evaporators iii- 18. If the temperature at the end of asuperheater be too high a thermostat operates the inlet `vaive in such a manner that more water will certainamount'may be introduced.y Thus,

for instance, the thermostat regulation vmay caused to act onV only a por-tion of the waterv supply, by providingV two' injection f nozzles or rosesV ortwo groups of thesame for eachevaporator, one of which supplies the injection water to be evaporated in normal working, while the vother, which is operated by a thermostat orl thelike, comes into operation only in exceptional cases.r Such vexceptional cases may be either `loads -eX- is in this instance, however, so regulated that a predetermined quantity of water fiows to it, which remains constant overa wide working range. The water which kdoes not evaporate flows away at 56. Should the water introduced through the roses 54 be'for any reasoninsufticient, so that in the subsequent superheater 60 or 61 the superheating eX- ceeds an admissible amount, the thermostat at 62 or 63 becomes operative and automati- V cally opens the valve 64, 65 which allows more water to How in until` the superheating temperature has sunk againk to the predeterminedmaximum amount;` y

Should it not be possible to' evaporate all the injected water at once or if the water be Vpurposely injected in eXcess, arsmaller or larger v.quantity of water' will accumulate in the bottomfo'f the evaporator. This water contains considerable quantities of energy in the formV of heat and pressure. It'v is therefore of particuiar limportance that it shall be, taken away and .collectedfwithout loss. Thus, a further objectof theapresent 'invention isv toprovide amethod of conveying away lthis excesswater fromthebodies in which the injection and evaporation takes place through lsuitable-,devices and of collecting it foi-further use. For this purpose the ifaporatorbodies may be provided in their lower parts with a small collecting space which is connected'with a larger collecting drum common to all the evaporators. This connection is by way of a floatioper'- ated valve or by a trapr' VThe lattermust be so vdesigned that while suilicient water vcan flow out, thep'assage of large quantities of stcam,for instance form one, evaporatorto the non, is prevented.` The c'oinmon collectingv drum is represented-in Fig.. 1 as the drum 25, and they common outflow pipe by 24. In Fig. 2, 45 lare the traps which @pesimo the @needing @para The com;

tions ofthe pump has mon collecting drum is yshown in section-at 47. In Fig. 5 the outlets 56 are shown but notvthe collecting' pipe and the drum.

Thev collecting'drum in which the excess injection water is collected mayse'rve a furtherpurpose. l It can also be used as a steam collector or a buffer vessel for equalizing the fluctuations in the steam consumption. If the superheaters and the evaporators in the new steam generator be regarded as corresponding in their action to the water tubes of ordinary steam generators, the accumulator represents the upper and `lowerdrums of. ordinary boilers, that is the parts by means of which the water to be evaporated and the already generated steam can be stored. Through the last evaporator 18being connected as shown in Fig. l by the Vpipe the .othery handy the last superheater 28 is connected with the steam4v dome 27, steam may, when there is a momentary excess of steam, be passed into the Water space of the drum 25 and be condensed there with an increase in pressure. is a momentary lack of steam,.steam may be withdrawn at l27 fromk the drum, the pressure iny the drum decreasing. The Water which was injected in excess into 'the heat exchange bodies (evaporators)" and passed away to the drummay be used again `Wholly or in part for injection purposes. vFor this purpose it must be brought up to the requisite injection pressure by a pump.

Conversely, when there li "34 with the distributor pipe.v 26, While on f This mode of operation isshown in the dia- .5100

grammatic view in Fig.' 2, in which 46 represents the pipek for conveying away the excess of' water and y47 the drum, whilethe pump referred'tois shown at 48 'and the moto'r vforfdriving it, for instancean electric 'i motor at 49.V The suction pipe of thepump -is connected to theldrumand the delivery pipeleads to the evaporators' 134-18 which mayalso be fed by the pipe 5 fromthe eX-l citer boiler.-.-When theginjection water is delivered entirely by'l-water which the pump 48 has withdrawn from the drum, the valve 70 is closed and the feed water rwhich vhas been preheatedin the exciterqboiler kor fresh feed water is delivered directly through the 115 pipe 71 to the drum. In this case-a float-operatedvalve 72V is required which' regulates the water level in the drum `47. Y

The pumpl 48 may with advantage vbe drivenby a steam turbine 7 3.` For ensuring reliable working, in addition to the steam turbine an electric motormay be ycoupled up as Well, which runs idle and is only supplied c with current when the number of revoluf sible amount.` f H For ensuring reliable yWorking and the sunk below ,an admisyproper functioning of the new steam igen# e-rator, variousdetailsare required which tion. Thus, the heat exchange bodies (evaporator bodies) must be provided With mud separators. Furthermore it may be necessary more particularly when the Water is introduced in a linely divided stateby means of injection nozzles, that the injection water shall have a considerably higher pressure than the steam. When the exciter steam and the injection Water are delivered from the same boiler, for instance as shown in Fig. l at 2 and 3, in other Words, When the Water and the steam are at the same pressure, the pressure of the steam must be artificially reduced for the evaporators. This may be efected hy a reducing valve, indicated by Way of example in Fig. l at 29.

From the manufacturing point of view it is an advantage for all the parts used to have the same dimensions. This can be effected by all the superheatcr parts having the same surface and being grouped about the furnace and in the flues in a similar manner. Furthermore, all the superheaters or superheater groups may be arranged one behind the other in such a manner, and their superficial area and the cross-sectional areas of the steam passages may be made such, for instance by placing several superheater parts in parallel, that for each superheater or group of Asuperheaters the evaporator bodies and the injection nozzles will be of the same size and construction.

The new steam generator provides the further great advantage that the boiler parts containing considerablequantities of Water and steam, as for instance the exciter boiler and the accumulator, are .separate from the superheater tubes, i. e. the parts actuallyV serving the purpose of steam generation and lying in the ues. This makes it ossible to disconnect some parts entire y Without having to interrupt the operation of the plant and to provide the superheater tubes withv nonreturn valves or valves which automatically disconnect a superheater tube from the rest of the steam generator on a fracture occurring in the said tube.

For the same reason the steam generator may be Worked as a rapid evaporator and a peak boiler. The superheater tubes in which the steam is actually generated may be made of smaller diameter than the` Water tubes of ordinary steam boilers. Hence, the thickness of the Wall of these tubes may be small, even for high steam pressures. The Weightvof the heating surfaces -is for this reason exceedingly small compared with a Water tube boiler having the same heating surface area. y The Water space and `the masses of the containers which in an ordinary boiler arerequired for containing these quantities of Water are also done away with. With suitable firing, for instance coal dust, the present steam. generator =can immediately commence to generate steam, as only the small masses of tubes of the superheater have to be brought up to the Working temperature, While the generation of steam commences immediately with the injection of the Water into the super-heated steam. here steam is required immediately, the steam will in general be dravvn immediately from the evaporators andsuperheaters. When, however, the drum is under pressure or there is s'uiiicient time to bring it up to pressure, the steam may be Withdrawn by Way of the said drum. Thus, the steam generator according to the present invention may be Worked, as required, as a tubular boiler pure and simple or, by connecting up the accumulator-like steam collector, asa boilerY having a large Water space.

1n order to facilitate the mode of operation described above, it will be seen to that the drum is always under pressure, i. e. that the Water in it is and remains at a temperature corresponding approximately to the Working steam pressure. For this purpose, when shutting off the boiler, the remaining steam Will be passed into the Water space and during working a portion of the steam Will be allowed to pass through the Water space of the drum.

In order that, when starting up, it may not be necessary to Wait for exciter steam to be generated in the exciter boiler, the exciter steam may in many cases be Withdrawn from other sources, for instance boilers having the same Working pressure which are in operation at the time. A further very useful method is the use of a so-called heat pump. Such a heat pump, more particularly When it should be a piston pump, makes it possible, even When the contents of the drum are vconsiderably cooled down, to obtain steam from the Water in the accumulator by suitably reducing the pressure and to compress the same to the pressure required in the superheaters. The heat pump may thus render the exciter boiler superfluous not only when starting' but also during normal Working.

In Fig. 6 the steam shown diagrammatically. The same parts have the same reference numerals as in Fig. l. Fig. 6 also shows the connection oli the pump for the injection Water, which is Withdrawn from the drum and the motor for driving the pump. In addition to this, 7 5 is the suction pipe for the heat pump Which itself has the reference numeral 76. '77v is the motor for driving theY pump. The figure also shows a connecting pipe 7 8 which can be shut olf by a valve 79 and enables excess n steam or thesteam generated after the Withdrawal of steam has ceased to be conveyed through all the superheaters and condensed in the Water space of the drum. As this Ygenerator is again lll drumin contradistinction to the upper `drum of normal boilers is capable of Working With a very variable Water level, it is possible, for

instance when a large quantity of steam has i to be received by the drum, to prevent an excessive increase in pressure by feeding in cooled Water.

Instead of being filled Withl Water the drum might also be filled With liquid having a high boiling. point in order to obtain high temperatures With only a small pressure in the drum. Y In this case the superheated steam must flow in the interior in coils, Where it condenses and gives off its heat to the liquid having a high boiling point. For generating additional steam or forV preheating the injection Water, Water is forced through these coils and the stored heat is in this Way Withdrawn from the liquid having a high boiling point.

IVhatI claim is: f

l. In an apparatus of the class described, a steam and Water drum, a series ofalternately connected'substantially dry evaporators and superheaters, an exciter boiler acting as an initial steam source and delivering steam through a superheater into the first of said evaporators, means for delivering Water from said steam and Water drum individually and in finely divided form into said evaporators, means for returning surplus Water from said evaporators to said steam and Water drum, and means for delivering steamv from the last of -said `series of evaporators to a place of consumption. i

2. An apparatus as described in claim l, filling elements in said evaporators adapted to distribute the Water. Y Y

3. In an apparatus as described in claim l, additional means for deliveringwater individually into said evaporators from said exciter boiler. Y v

In testimony whereof I have signed my name to this specification.

WALTER GUSTAV NOACK.

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