US1723340A - Steam generation - Google Patents

Description

1929- L i i PQFABER- 1,723,340

STEAM GENERATION Filed Nov. 24, 1926 2 Sheets-Sheet 1 Aug. 6, 1929.

PR FABER STEAM GENERATION Filed Nov. 24, 1926 q2 Sheets-Sheet 2,

fm2/275# 1 Ped f er:

Patented Aug. 6, 1929.

UNITED-STATES rATENT OFFICE.

PAUL FABER, OF BADEN, SWITZERLAND, ASSIGNOR T AKTIENGESELLSCHAFT BEOW'!!l BOVERI & CIE., 0F BADEN, SWITZERLAND, A JOINT-STOCK COMPANY 0F SWITZER- LAND.

STEAM GENERATION.

Application filed Nbvember 24, 1926, Serial No. 150,462, and in4 Germany December 4, 1925.

This invention relates to apparatus for the generation of steam under pressure.

A general object of the invention 1s the provision of apparatus particularly adapted 5 for the generation of steam at high pressures by virture of the elimination of factors which constitute elements of danger in the operation of steam boilers.

Another object is the provision of appavratus whereby steam may be generated at hi h pressures and an appropriate margin of saety maintained in the construction of the heat transfer apparatus without requiring the use of excessive heavy construction in the pressure confining parts.

A specific object is the provision of apparatus whereb the dangers and losses accruing from sca e deposits in the heat transfermembers are substantially eliminated.

A further object is the provision of apparatus'. for the generating of pressure steam by indirect heating which does not require a pump for circulating the heating medium.

urther objects includethe provision of 2@ an improved organization of steam generating equipment and of various features as herelnafter described.

Other and 'further objects will be pointed. out or indicated hereinafter, or wili be apparent to one skilled in the art upon an understanding or the invention or its employment in practice. v

In the 'accompanying drawings forming a part of this specication I illustrate in diagrammatic fashion certain organizations of apparatus wherein the invention may be embodied and practiced, but it is to Qloe understood that these are presented simply by way of example for illustrating the principle of the invention, and that references thereto are not -to be construed in any fashion having the eect of limiting the appended claims short of the true and most comprehensive s'cope of the invention in the art.

In said drawings,

Fig.l 1 is a diagrammatic illustration in the nature of a vsectional elevationof a steam generating plant, and

Fig. 2 1s another diagrammatic illustration in the nature of a sectional elevation of-a steam generating plant of a modi-y ed design.

g Described generally, the present invention rated condition and is `passed through a concerns a method and apparatus for generation of steam under pressure, in which the steam is' generated in stages by the heating of water by means of superheated steam, the steam thus produced being itself subjected to superheating and employed in whole or in part` as the heating medium forv the generation of additional steam from water, the steam being circulated from stage to stage as a result of the natural pressure dropA between the steamy at the superheat temperature andthe evaporation temperature. y

The nature of the invention willfbe understood more in detail by reference to the examples illustrated. In Fig. 1 of the drawing the reference numeral 10 designates a furnace which is fired in the main combustion chamber 11 and auxiliary combustion chamber 12. The combustion chamber 12 serves an initial steam generator 14 in which water 75 is directly heated from combustion of fuel therein. Steam thus generated in initial generator 14 is led through a superheater 15, which is subjected to the heat of the main furnace. From the superheater 15 the superheated steam passes to a rst stage generator 16 containing water into which the i .superheated steam is injected through an appropriateA nozzle or distributor 17. The superheat is given up to the water in generator 16, and a quantity of the water evaporated. The initially superheatml steam, tegether with that generated in @rst-stage generator 16 issues from the latter in a satusecond stage superheater 18. From this it passes to a. second stage generator 19, undergoing a natural drop in pressure and is there injected through the water contained therein, for the production of saturated steam. This .then passes tothe third sta superheater 20, and, with a repetition of t preceding steps, throughy a third stage generator 21, fourth stage superheater 22, fourth stage generator 24, fifth stage su erheater 25 and fifth stage generator 26. team issued from the final generator 26 is given a final superheat in the final superheater 27, whence it passes by way of the line 28 to the engine or point of use. The generators are supplied by the way of lines 29 and 30 with condensate andI raw feed water.

The' higher the superheat and the lower the heat required to evaporate the water, the larger will bejfthe amount of steam generated in each of the stage generators. invention is7 particularly suitable for generation of steam under high pressures as in such instances the heat of evaporation is low. Assuming that the temperature of the superheat is the same in the several stages and that the feed temperature is the same inthe several generators, the ratio of weight of Water evaporated per stage to Weight of evaporating steam will be constant. For example, let the weight of steam generated in the initial generator 14 be G andthe quantity of water evaporated in the iirst stage generator by the superheat be Ga, where a is less than unity then the quantity of saturated steam leaving the first stage generator will be (H1-lia). After the second stage generator, the quantity of saturated steam available will be G(1la) 2, and after the nth stage the quantity will be G(1+0J). Thus it will be seen that the quantity ofsteam available increases rapidly with the number of stages. Hence the amount of steam necessary to be generated in the initial generator 14 can be kept quite small and require only a very small boiler for its generation by direct heat. It will be observed that with this method of steam generation, there is substantial elimination of necessity for heat transference to the water through the walls of the water containers, the only instance in which this 1s necessary being in the initial generator 14. As a result the conditions for scale deposit in the water containers are substantially eliminated and the same is true with respect to heat losses from such deposits as may be formed. Due to the comparatively small amount of feed water required for the initial generator, that generator may be supplied with pure feed water and scale deposit thereby eliminated without appreciable cost. By evaporating in a number of stages, the loss of energy in the steam is kept low, so that boiler losses due to steam circulation is only a small fraction of the energy which would be necessary for circulation by pump.

The initial generator 14 may be of any ap' propriate type of boiler and may be fired either from its individual furnace as shown in Fig. 1, orlfrom the main furnace as shown in Fig. 2.

In the -embodiment illustrated diagrammatically in Fig. 2, parts corresponding to those in Fig'. 1 are designated by like reference numerals. The initial generator 14 is located in an appropriate position in the main furnace 11, and the stages of the superheater are disposed in an order which is reversed to that illustrated in Fig. 1,sothat the steam progresses toward the combustion Hence the chamber through the successive superheaters. The stage generators are combined as compartments within the unitary shell 23. Inasmuch as the difference in pressure fin adf jacent generatorI stages does not exceed the sum of the resistance to the flow of thesteam in the superheater coils and in the water in the generators, the partitions forming the generator compartments need not be of great thickness. Since the quantity of heat abstracted from the hot gases to raise the progressively increasing volume of steam to the desired temperature must increase from stage to stage, provision should be made to accomplish that result by` increasing the heat transfer surface of the superheaters from stage to stage, or? increasing the temperature difference between the hot gases and the saturated steam, or by increasing the velocity of ow in successive stages. These various means may also be employed in combination, as by the arrangement illustrated in Fig. 2. The temperature/to which the steam is superheated should be approximately the same in each stage ofuthe superheater, and should be carried to the highest possible pointrpermitted by the superheater construction. The attainment of this result may be accomplished by arranging all the superheater coils in parallel relationship, and arranging the connections so that the steam flow is in the direction opposite to the iiow of the hot gases] The superheating in the final superheater need only be suiiicient to give the desired temperature at the enp gine, and consequently may be to a lower temperature than in the inter-stage super heaters, thereby affording an over-all pressure drop between the initial and final superheaters. In order that the steam delivered to the water in the stage generators, which is subdivided as minute bubbles by the distributing nozzles, may be able to give up its superheat to the water for the generation of fresh steam, and to insure that the separation of the steam from the water proceeds regularly, it is necessary that the area of water surface exposed in successive genera tor stages increase progressively from stage to stage, such increase corresponding to t e increase in the quantity of steam generated.

What I claim is:

In steam-generating apparatus, plurality ofwater tanks, and su erheaterelements seriall connecting said boiler and tanks, said e ements being connected between tanks adjacent in the series, and connections providing for the supply lof water to said boiler-.and tanks.

In testimony whereof I have hereunto subscribed my name.

a boiler, a l

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