US1917166A - Indirect generation of steam by means of superheated heating steam - Google Patents

Description

July 4, 1933. H. TRE'DE ET AL INDIRECT GENERATION 0F STEAM BY MEANS OF SUPERHEATED HEATING STEAM Filed Feb. 7, 1929 4 Sheets-Sheet 1 Fig. 1.

Fig. 2.

lavevnfirs: Han/6 Iiede and y 1933. H. TREDE El Al. 1,917,166

INDIRECT GENERATION 0F STEAM BY MEANS OF SUPERHEATED HEATING STEAM Filed Feb. 7, 1929 4 Sheets-Sheet 2 Fig. 3.

fiwenvrs: Harts Trade and O%][.Harnmw,

QM WQ 4 Sheets-Sheet 5 H. TREDE ET AL Filed Feb. 7, 1929 July 4, 1933.

INDIRECT GENERATION OF STEAM BY MEANS OF SUPERHEATEID HEATING STEAM y 1933- H. TREDE ET AL 1,917,166

INDIRECT GENERATION OF STEAM BY MEANS OF SUPERHEATED HEATING STEAM Filed Feb. 7, 1929 4 tsheet 4 Fig.5.

' Ivor/6211276: Jfana Trade and Ofla J1: Harfinann Patented Jul 4: 1933 J y p sass rarest crates I HANS TBEDE AND OTTO H. HARTMANN,

ASS GENRES T0 SOHMEDTSCHE HEISSDAMPE-GESELLSCHAFT lVIIT BESCHRANKTER TU 181G 01 KAESEL VJILH.ULMSHOHE, GERMALTY, A CORPORATIQN OF GER-MANY OI KASSEL-WILHELMSHOHE, GERMANY,

INDIRECT annnsii rion or srnaia BY MEANS or sUPnnHnA'rnn HEATING'STEAM Application filed February '3", 1829, serial No.

heating element, the heat required for evap crating the Water in the boiler drum should be given up in the form of superheat and lat-v ent heat; and in certain cases, moreover, part of the necessary heat is taken from the sensi ble heat of the condensed heatcarrier.

By reason of such requirements,definitelimits are imposed on the range of utility of known methods. 1

As a rule, the pressure of the heating steam: must be higher than that of the steam generated, because only in such conditions is it p0;- ible to impart the necessary heat content to the heating steam.

Our present invention affords a method by which steam can be generateduindirectly by the use of the superheated steam Without the necessity of satisfying the condition or requirement above set forth. f

On the contrary, it is possible to apply as the heat carrier heating steam of any desired pressure, and in particular steam of a lmv-pressure, and at the same time to generate Working steam of any required pressure even up to the critical point.

V fith this object, successive transfers of heat to'the Water to be evaporated are eii'ccted by leadin superheated heating steam alternately through superheater elements heated from the outside and through heating elements lying in the evaporator drumn The present invention consists in the use as heat carrier of Working steam which isled through heating on its Way from-the generator to thoengine, heat exchanger or the 7 e, Where it is used, the pressure oi genbeing higherth an the working" sure the place-Where it is used by such an amount that the difference of pressure secures the i'lOW of heating steam through the stages. I

l Vith the new method ofivo'rkii no special auxiliary a;paratug such as circulating pumps, necessary in or er to drive the heating steam through the heating elements, nor

338,156, and in Germany February 15, 1928.

is such a considerable degree of cooling required that the difference of Weight of the heating steam in the inlet pipe and the condensate in the outlet pipe is relied on to en sure floyvthrough the heating elements.

The number of heating stages is determined according to the conditions of the particular case concerned.

For example, if high-pressure steam of 50 atmospheres is to be generated and steam of 17 atmospheres superheated to 47 5 C, is used as heating steam and is taken in the form of saturated steam from an existing boiler plant, the number of heating stages is determined as follows:

The heat content of the heating steam of 17 atmospheres pressure and with a superheat of 475 C. amounts according tothe usual steam table (Mollier entropy diagram) to 815kcal/ (g. In respect of this heat content, a fall oftemperature is available to the temperature of the saturated steam to be generated at 50 atmospheres,that is to a temperature of about 268 0., the assumption that is 4.15 stages or in practice 5, or to give a certain reserve, 6 heating stages would be provided. o

If it is desired, With the same heating steam, to generate high-pressure steam of 224 atmospheres, that is, of the critical pressure, heat must be supplied to the amount of 508200=808 kcal/kg. The temperature of saturated steam at 2% atmospheres is-about 374 0., and the heat content of the heating steam of 17 atmospheres at this temperature is about 768 kcal/kg. so that the available f heated to 4:75 6., and the temperature of the heat is815763=52 kcal/k The number of heating stages is therefor? that is 5.92 stages.

In this way, for any desired pressure up to the critical pressure of the working steam totity, then X-times the number of heating stages shown by the above calculations must be used.

,lVith the present invention, the pressure of the heating steam can be chosen within wide limits and in particular steam of very low pressure can be etliciently used as heating steam.

For example, it working steam of atmospheres is to be generated by means of heating steam of 1.45 atmospheres superfeed water is C., then for the evaporation of a kilogram oi water at 105 C. in the Working boiler, 664.5105, i. e., 559.5 kcals are necessary. From the steam table the heat content of the heating steam superheated to 475C is 818 kcal/kg. and at the temperature of the saturated steam to be generated at 50 atmospheres, that is 263 C., it is 715 heal/kg, so that the heat available is 8lS-7l5=103 heal/kg.

- It will be seen, therefore, that in this case the number of stages amounts to The necessary heatingsteam can be taken from any suitable steam generator, for eX- ample, as mentioned above, from an existing low-pressure boiler.

The present invention, however, is not confined to the application of heating steam whose puressure is lower than that of the steam to be generated. It is, for example, possible to utilize indirectly-generated highpressure steam as heating steam and to lead it from the evaporator directly without loss of pressure to the first heating stage. Further, if desired, the pressure of the heating steam taken from the indirectly-heated evaporator may be reduced before admission to the heating stages.

When heating up a boiler according to the present invention, it is important to provide for the generation of heating steam in the heating-stean'rsuperheater itself from dis tilled water introduced into the first superheater stage, such water evaporating in the first superheater stages and being superheated in the following stages.

In order, therefore, to accelerate the gen 5.43 stages.

eration of steam in the superheater, the pressure in the heating system is reduced by leading the heating steam from the last heating stage into the atmosphere or into a condenser.

For the generation of high-pressure steam of a given temperature in accordance with the present invention, the choice of heating.

heatin sta es of the hi 'hressure'steam generator can be built into the existing boiler.

The admission steam pressure of the existing engine installation is reduced in comparison with the pressure before alteration of the plant, so that in this way the pressure drop necessary for causing the heating steam to flow through the heating stages is obtained and the outlet steam coming from the heating stages may be admitted to a lowpressure stage of the engine In all cases, due to the fact that the flow of heating steam through the heating stages is ensured solely by a pressure drop between the heating-steam inlet and outlet, the advantage gained that the high-pressure evaporator may be arranged in any desired position, as, for example, at a level below that of the heating-steam generator.

In the accompanying drawings, different constructional forms of the invention b vay of example are shown diagrammatically for carrying out the present method of work Figure 1 shows a vertical section of an indirectly-heated steam generator applied to a marine cylindrical boiler of usual construction;

Figure 2 being a cross section on the line HII of Figure 1;

Figure 3 shows a longitudinal section of a modified form of a marine steam boiler installation;

Figure shows a cross section of a station ary boiler plant; while i Figure 5 shows a longitudinal section of a locomotive and Figure 6 a diagram of a modified form of construction of a two-pressure boiler installa, tion.

In the form of the invention shown in Figures 1 and 2, the cylindrical boiler, 1, serves for the generation of the low-pressure steam while high-pressure steam is generated in the drum, 2, by the indirect method of heat ing. V

The hot gases from thefurnaces, 3, pass through the reversing chamber, 4, and the cal boiler and the first super-heater element is connected a heating-steam pipe, 10, while from the heating element, 9,0f the last heating stage, an outlet steam pipe, 11, is led to the outside of the steam drum. The connecting pipes, 12, between a superheater element, 8, and the corresponding heating element, 9, as well as the connecting p1pes,1'3,

between a heating element,f9, and the next following superheater element, 8, are'each led respectively through one of the smoke tuhes,5, p I v The heatin'g'steam from the boiler, 1, flows therefore through the inlet" pipe, 10, into the. first superheater element, 8, then to the first heating element, 9, in the boiler drum and thence alternately through a'superlnmter elementand an evaporator element till it passes from the last evaporator element, 9, through the exhaust pipe, 11,-to the place where it is used. i

To the steam inlet pipe, 10, a feedpipe, let, is connected through which in case of need distilled water can be introduced into the first superheater stage, 8, so that in this Way heating steam can be generated in the first heating stage itself. The necessity may arise,

for exam 31s in heatin u the boilerbefore the low-pressure boiler has started'to make steam. In order to accelerate the generation o't'steam in the heating stages, the heating system is connected a pipe, 15, branching on from the outlet pipe, 11, toa condenser. By

a feed pi can be passed to the steam-and-wat'er drum, 2. The high-pressure steamgenerated in the evaporator drum is led through a pipe, 20, into a superheater arranged in the reversing chamber of the cylindrical boiler, 1, from which the superheated high-pressure steam flows through a pipe, 22, to the cylinder, and thence to the cylinder, 24, of a-compound high-pressure engine. The steam'from the low-pressure cylinder, 24, exhausts into the heating-steam outlet pipe, 11, coming from the-heating sta es so that the hlgh-pressure exhaust steam is mixed with the heating steam. As the temperature of the higb-pressure steam generated indirectly in the drum, 2, is substantial- 1y higher than the saturated-steam temperature of the heating steam, the heating steam which each consists pe, 18,-provid'ed with a pump, 19, feed water from the low-pressure boiler, l,

flowing in the pipe, 11, from the heating stages is still superheated and in consequence the mixture formed from the high-pressure exhaust steam and the heating steam is suit-' able for dolng work 1n a low-pressure steam ture does work in the cylinders, 26 and 27, of the machine installation originally present,

the new high-pressure cylinders, 23, 24, being added to the existing cylinders, 26, 27. The admission pressure of the steam to the cylinders, 26-and 27, is reduced as compared with the corresponding pressure before rebuilding so that compared to the admission pressure of the heating steam to the first heating stage, which corresponds approximatelyto the orig" inal boiler pressure, a sufficient pressure drop is provided to ensure an eiiicient velocity of flow through the heating stages.

In the form of the invention shown in Figure 3, the heating steam is also generated in a cylindrical boiler, 28, with smoke tubes, 29, the flow of hot gases corresponding to that of a ships boiler with return flue. The furnace is not, however, arranged in the flue but in a combustion chamber lying below the boiler, 28,'this combustion chamber, 30, being shut oif with respect to the boiler, 28, by acover, 31. i

The products of combustion from the furnace aredrawn rearwards into a vertical fine, 32, which is formed by a cross wall, 34, introduced into the reversing chamber, 33, the gases after passing through the fine, 32,

flowing through the reversing chamber, 33,

into the smoke tubes, 29, and thence to the uptake, 35.

The indirectly-heated steam-and-water drum, 2, liesabove the front part of the combustion chamber and is protected from the direct action of the heat o'fth'e furnace by 2 cover, 36.

Each ofithe successive heating stages, of

which for the sake of cleai*ness only four are'shown, consists as before of a superheater element-and a heating element. The supered. the heating-steam inlet pipe, 40, through which is led the heating steam generated in the boiler, 28. To the heating-steam inlet pipe, 40, is connected a feed pipe, 41, through.

which'on heating up the installation distilled water may be fed into the heating element of the' first heating stage so that heating steam may be generated in the superheater. The heatingsteam flows alternately through asuperheater element, 38, and a heating ele-- incnt, 39, and is finally led from the last heating element through the heating-steam outlet pipe, 42, to the place where it is used. From the outlet pipe, 42, branches off a pipe, l3, by means of which the heating stages during heating up can be connected to a co ndenser.. The highepressure steam generated indirectly in the drum, 2, flows through a pipe, 44, to; a superheater, 45, arranged in the flue, 32, and thence through a pipe, 46, to wherever it is required.

While in the form of the invention described, the heating steam is generated in a low-pressure boiler, in the stationary boiler shown in Figure 4, the heating steam is taken from the 'indirectlyeheated high-pressure drum, 2, in a manner already known in :onnection with other methods of steam generation. T ie drum, 2, lies above the furnace which is provided with nozzles so that it may be tired either with oil or pulverized coal. The combustion chamber, 48, forms a vertical flue which at its upper end connected by a horizontal flue, 49, with asecond vertical line, 50, into which the hot gases are drawn in the direction from above downwards to the chimney. The h ating ele- \nents,'51, lying in the steam drum, 2, as before, alternate with superheater elements heated from the outside.

Three of the superheater elements shown, namely, the superheater elements, 52, are arranged on the walls of the combustion chamber and receive radiant heat from the furnace. In the fourth superheater element are interposed the tubes, 53, forming in known manner acooling grate for the slag while the superheater element, 54, to the last heating stage is arranged in the horizontal flue,.49. From the last heating element, 51, the heating steam is led first through a superheater, 55, lying in the flue, 50, and thence through a pipe, 56, to the place where it is used. I

In order to be able to generate heating steam in the superheater elements of the heating stages during heating up, a steam pipe, 59,is connected to the heating-steam inlet pipe, 58, leading to the first superheater element, 52, while a pip-e, 60, leading to a condenser is connected to the heating-steam outlet pipe, 56.

The high-pressure steam generated in the drum, 2, flows through a pipe, 61, to a superheater, 62, lying in the flue, 50, and thence through a pipe, 63, to the place where it is used.

Below the superheater, 62, in the fine, 50, a feed-water heater, 64, is arranged from which the preheated feed-water is led through a pipe, 65, to the steam drum, 2.

The superheater elements of the heating stages in this form of invention are, as will be seen from the aboveexplanation, built and arranged in a different manner and are disposed essentially so that the superheating elements through which the heating steam of higher pressure passes lie where the highest combustion-chamber temperatures rule,

- while the following superheater elements corresponding to the fall in pressure of the heating steam as it passes through the heating stages are arranged at points of lower temperature. This arrangement gives the advantage that the heating steam. which has the greatest density flows through the superheater elements subje'cted'to the highest temperature so that the latter are efficiently cooled and protected from burnin It is obvious that the area of the heating surfaces of the successive heating stages must be designed to suit the above-mentioned conditions.

In the diagrammatic drawings this point, which is valid for all forms of the invention shown, has not been taken into consideration. In the locomotive shown in Figure the heating steam is again generated in a lowpressure boiler, in the present case of the longitudinal type, below which'the steam drum, 2 is arranged.

The superheater elements, 69, of the heating stages which alternate with the heating elements, 70, lying in the drum, 2, extend to the fire-box through a large-diameter tube, 71, provided in place of the usual smoke tubes. The heating steam is led from the steam drum, 73, through a pipe, 74, to the heating element, 69, of the first heating stage and from the heating element of the last heating stage through a pipe, 75, to thelowpressure cylinder, 76, of the locomotive.

To the heating-steam inlet pipe, 74, as before, a feed-pipe, 78, is connected and to the heating-steam outlet pipe, 75, a branch pipe,

79, through which the heating steam during heating up can pass into the atmosphere.

The high-pressure steam generated in the drum, 2, is led through a pipe 80, to a superheater, 81, lying in the tube, 71 and the fireboX, 72, and thence through a pipe, 82, to the high-pressure cylinder, 8 V I The exhaust steam from the high-pressure cylinder flows through a pipe, 84, to the heating-steam outlet pipe, 75, to mix therein with the heating steam before admission to the low-pressure cylinder, 76.

In contrast to the form of the invention shown'in' Figure 4, in which from the inclirectly-heated steam drum only a part of the higl1pressure steam is taken to serve as heating steam for the heating stages, while the other or larger part of the heating steam is led after superheating directly to the engine, in the form of the invention shown in Figure 6, the whole of the high-pressure steam generated indirectly in the boiler drum, 2, flowsthrough the heating stages before passing thence to the englne.

The heat ng stages each consists of a superheater element, 85, arranged as radiant heatreceiving surfaces in the furnace and heated from outside and a heating element, 86, lying in the boiler drum, 2. To the first superheater element, 85, is led the whole of the high-pressure steam from the drum, 2, through a pipe, 88. .This steam then flows alternately through a superheater element,

85, anda heating element, 86, and passes from the last heating element, 86, to the heatingstage outlet steam pipe, 89.

To the first superheater stage, 85, is connected a "feed pipe, 90, and to the outlet pipe, 89, is connected a branch pipe, 91, through which, when heating up, the outlet-steam pipe can be connected to atmosphere orto a condenser. he exhaust steam pipe, 89, is connected by w y of a control valve, 92, with a sup-erhcater, 95, lying in the smoke tubes, 93, of a smoke-tuhe boiler, 94, from which su'erheater a pipe, 96, leads to the high-press 1 stage ofthe engine In addition, a branch pipe, 99, provided with a control valve, 98, is led from the outletsteam pipe, 89, into the water space of the smoke-tube boiler, 94. It the valve, 98, is closed, all the high-pressure heating steam passes through w superheater, 95, and the pipe, 96,,to toe high-pressure stage of the engine after it has served in the heating stages by alternate superheating and giving up heat to generate high-pressure steam indirectly in the drum, 2. i

The admission pressure in this stage of the engine isso much less than the working pressure in the drum, 2, that the necessary veloci y of flow is ensured through the heating taees.

Since, in the heating elements, 86, and especially in the last heating stages, the heating-steam pressure is less than the working in the heating elements cannot cool down to pessure in the drum, 2, the heating steam a temperature cmrespondinpto the tempera ture of saturated steam at this lower heating steam pressure, andconsequently cannot condense when flowing through the heating ele-' ments.

On the other hand, the result of opening the valve, 98, is that a part oi the heating steam coming from the heating stages flows into the water space of the low-pressure boiler, 94:. This traction of" the heating steam flowing into the low-pressure boiler, 94, can be regulated by appropriate adjustment of the two valves, 92 and 98.

In the case when all the heating steam is admitted into the low-pressure boiler, the necessary pressure drop is likewise obtained in order to secure an el'licient flow of the heating steam through the heating stages.

The steam generated in the low-pressure hoiler,,91, flows through a pipe, 100, to a superheater, 101, arranged in the smoke-tubes,

93, of the boiler, 94, and thence through a pipe, 102, to the low-pressure stage of the engine.

What we claim is:

1. Steam generating plant comprising in combination an indirectly heated steam boiler, a source of heating steam, and heating said water and then alternately superheating' it and passing it in heat exchange relationship with said water without mixing it therewith a plurality of times, and finally utilizing it at a pressure lower than its initial pressure thereby to induce a flow thereof.

3. Steam generating plant comprising a boiler drum, a plurality of heating elements in the drum, a plurality of superheaters, said heating elements andsuperheaters being alternately connected. in series, and a conduit connecting the steam space of said drum with said series connected superheaters and heating elements.

4. In a multi-stage boiler installation generating working steam at a plurality of pres sures in a plurality of sections for discharge to a plurality of working points, a plurality of heating elements in one of the sections, a

plurality ot superheaters in the path of the furnace gases, said heating elements and suerheaters beine alternately connected in series, and a conduit connecting the steam space of one of the boiler sections with said series connected superheaters and heating elements to supply steam to said elements at a pressure not greater than that of the steam in the section containing the heating elements. 5. The method of continuously generating steam from a body of water, which. comprises successively passing heating steam in heat exchange relation with a flow of hot gases to'superheat the same and then passing the thus superheated heating steam in heat exchange relation with said water a plurality of times, and finally utilizing theheating steam for the performance of mechanical work at a pressure lower than its initial pressure, the heating steam being at least a portion of the steam generated from said body of water.

' In testimony whereof we affix our signatures.

HANS TREDE. OTTO H. HARTMANN.

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