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Патент USA US2126248

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Aug. 9, 1938.
Filed March 12, 1937
2 sheets-sheet 1
wafer *deo/77
Aug. 9, 1938.
“ 2,126,248
Filed March 12, 1957
42 sheets-sheet 2
F1a. 6.
und Ffm
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Mam-:N EULE .1
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Patented Àug. 9, 193s
UNITED NsrATes PATENT orsi-cs- ' ‘
STEAM GENERATOR wrm Foiaoni)` pas'-`
Martin Eule, Berlin-Spandau, Germany, assigner
to Siemens-Schuckertwerke Aktiengesellschaft, ,
Berlin-Siemensstadt, Germany, a corporation
of Germany
Application March 12, 1937,` Serial No. 130,477
In Germany November 23, 1934
` 3 claims. (ci. 1272-443)
My invention relates to steam generators of the superheater arrives, as a rule, too late. The
the forced-flow tubular type and it has for an regulation effected by this impulse, consequently,
object to provide a control system therefor -lagsï considerably, whereas the derivation of the
, wherein elTec'ts of lag, so far as the temperature
5 impulse `is concerned, are substantially avoided.
This application is a continuation in part of
application> Serial No. 50,860, ñled by me on
November 21, 1935 for Steam generators with
forced passage of the operating medium.
A further and more particular object of my
invention is to modify the steam-producing con
ditions of one ofthe tubes of a plurality of
parallel-connected tubes so that said tube will
`have a region of variable temperature over
lapping a portion of the evaporation zone of the
remaining tubes, or within the physical limits
of the latter, whereby there is provided a tube
region of Variable temperature within the main
evaporation zone and which region may be used
to provide a temperature impulse for the con
trolling apparatus.
In steam. generators of the above character,
the supply of the operating medium and the
. fuel must be varied in such a manner as to ap
25 `proximately maintain a. predetermined ratio of
both operating mediaif in the case of variations
of load the condition of the steam produced is
tolremain unchanged.
This may be also ac
complished by the two regulating methods which,
as a rule, have hitherto been employed. >By one
of the regulating methods the operating medium
`and the fuel is simultaneously supplied Ain a>
greater or smaller amount depending upon the
desired output, in which case a Correction im
35 pulse is caused to be transmitted in response to
the steam temperature for ensuring a reliable
regulation thereof, which impulse in addition
acts upon the supply of fuel. According to the
other method >the supply of the operating me
V40 dium and the fuel is not varied simultaneously,
l 30
impulse at the preheater is effected so prema
turely that considerable variations of the oper- v Ul
yating conditions may again occur at the end of
the -generator.` No temperature impulse may be
derived from the‘part of the heating surface
lying between the preheater and the superheater‘;
i. e., from the evaporatingfheating surface of the 10
generator, since the temperature of the operat
ing medium during the evaporation remains un
The -`object of the-present invention is, there
fore, to-utilize the part~of the heating surface
lying betweenfthe preheater and the‘superheater
for the‘transmissionof the impulse.
The "essence of the invention consists in gen
eral inthe fact that the supply of heat or `of
the' operating medium to one of the tubes con '.20
vne'cted'in parallel and forming the heating sur
>4`face is so regulated with respect to the-other
Ttubes that in this partièulartube the preheating
»terminates later ‘or the superheating begins earï
lier than in the other tubes and that the tem
perature impulseis derived frcmthis tube from
a `point wherethe preheating terminates or the
'superheating begins.
NvIf the impuls-e in response to the temperature
fof the superheated‘steam is to be transmitted,
in due time, ther-tube destined for the supply'of
`the impulse must experience with respect to the
`other tubes a decreased supply of the operating
f medium or an increased supply of heat. Depend
ingiupon the extent, `to which the decrease or p
increase of thefsupply of beth mentioned oper
`ating vmedia isbrought about, the superheating
Vin the tube supplying‘the impulse, measured ,ac
:cording to the length of ‘the tube, will commence
correspondinglyïearlier ¿than in the other tubes.
but in succession; that is tosay, the» supply of . It is thus possible to` derive `the `temperature »im
the operating medium is at ñrst adjusted to the ‘pulses to a'sufñcient extent from a heating sur
vdesired new value and then the supply of fuel face part which normally forms the evaporating
is regulated by an impulse,Ã derived in response `heating surface. In practice, this `may be ac
to a variation of the temperature of the steam „complished in the simplest manner by reducing 45
produced. In both regulating methods, the deri
the supply of operating medium tothe measuring
vation of an impulse in response to the tempera » tube with‘frespect to the other tubes. In 'this'
tureof the steam produced plays an important i case, it is only necessary to insert in this tube
part. For the transmission ofthis temperature in the path of flow at a suitable point, preferably
i150 impulse only two'points of the heating surface inthe zone in which the operating medium is» 50
of the steam generator had hitherto been taken still liquid, a resistance correspondingly rated.
into consideration; viz. the superheater and the Dependent upon the magnitude of this resist-V
preheater. The derivation of the impulse from » ance, theppoint at which the superheating begins,
these parts of the heating >surface is, however, ,willydisplace itself in the measuring tube more
not fully satisfactory. An impulse derived. from’ i or :less opposite‘to the` direction of flow of the! 55
It has hitherto been customary in steam gen
erators with forced passage of the operating me
ture impulse necessary for the regulation of the
generator may be then derived from this heating
surface point, at which the superheating begins.
It suffices if the supply of the operating medium
dium to arrange at least one part of the heating
surface, in which under normal operation the
or the supply of heat for this measuring tube is la
so regulated that the steam flowing from this
conversion of liquid into steam is effected, as con
tact heating surface in the path of the fuel in
vtube into the salt separating drum is only slight
order to prevent a burning out of the tubes due ’
Thus, it will be seen that, in all applications
of the invention, a plurality of parallel tubes are
operating medium with respect to the other
principally in this phase of production of steam
to salts depositing from the operating medium.
Since, with a measuring tube having means pro
viding for its superheating Zone being displaced
forwardly relatively to the superheating zone of
the other‘tubes, the other phases or zones of
steam production of the measuring tube are
also displaced to» more or less extent in the direc
tion opposite to flow of working fluid, with vthe
result that the salt deposit zone of the measuring
tube may not remain Within the contact or con
vection heating region of the generator Ybut be
shifted into the radiant heat zones; and, in con
sequence, it may happen that the measuring tube,
because of the wandering of the phases of steam
production and creeping of the salt deposit zone
into the radiant heat zone, -or zone of high heat
intensity, may have salt deposited in portions of
the surface thereof subject to such high tem
peratures and give rise to burning out of the
measuring tube, this objection having already
been lavoided by the intentional displacement of
the salt‘deposit zone of the remaining tubes into
the contact or convection heating surface where
>such a »relatively low temperature normally ob
tains as to avoid burning out of tubes, even
though depositsrof salt should occur.
The other solution, as above _generally stated,
of the probleml upon which the invention is based
prescribes that at least' one of the parallel con
nected tubes should experience an increased sup
Vply of operating medium or decreased supply of
heat with respect to the other tubes and Vthat
ly superheated.
arran'ged'to have at least one thereof serve as
a measuring tube in order to provide a controlling
temperature impulse so that lag may be mini
mized. Any suitable means may be employed
to secure offsetting of the zones of steam pro
duction of the measuring tube with respect to
such zones of the Vremaining tubes, the essential
feature being to provide for the temperature im
pulse being taken at a point of variable tempera
ture along the measuring tube and falling Within
the physical limits of the evaporation zone of the
remaining tubes.
In the drawings, Figs. 1 to 5, inclusive, are dia
grammatic views` illustrating the essential feature
orcharacteristic of the present invention;
Fig. 6 is 'a diagrammatic view showing the ap
plication of the principle of Figs. l, 3, and 5;
Fig. '7 is a diagrammatic view showing the ap
plication of the principle of Figs. 2 and 4.
Y _ Figs. 8 and 9 are diagrammatical sectional views :30
of ilow control or throttling devices for the tubes.
The present invention is illustrated in diagram
matic form in Figs. 1 to 5. VThe tubes forming
the heating surfaces are diagrammatically repre
sented in the form of heavy lines. The ends of
the tubes enter collecting or distributing vessels.
The direction of flow of the operating medium is
indicated by the arrows as shown. Flow control
or throttle points in the tubes are indicated by
cross lines intersecting the tubes, whereas the
temperature points are indicated by small Ycircles
drawn on the tube lines.
Insofar as the flowfcon
the temperature impulse should be derived from ' trol or throttle points are cut oft" or the tempera
this particular tube at the point, at which the ture measuring points are not used for the regu
preheating ends.
It may be further stated that the invention
has a particular importance for such steam gen
erators which are fed with an excess of operating
medium, and in which the steam before the be
ginning of its superheating hows into a drum,
in which the excess of water is separated from the
steam produced up to that moment and is car
ried off from the generator. For such steam
generators it was hitherto not possible rto de
rive for the boiler a temperature impulse suit
able for regulating purposes before the separat
ing drum.Y If the invention is to be 'applied for
these steam generators two methods are possible
according to the invention. In accordance with
one method, the preheating zone is displaced, as
lation the corresponding symbols are shown in all .
figures in dashes. In all figures the lowest of
the three tubes serves for the reception of the
impulse which as above described may alternately
be derived from the one or the `other of the
tubes shown by the use of change-over 'devices
not shown.
The diagrammatical representation
which shows only three tubes is to be considered
only ‘as an example; the number of the tubes
-may vary at will.
Figs. l and 3 show the conditions for the case, 55
in which the impulse is transmitted in response
`to the temperature of the superheated steam,
the time at which the superheating begins being
displaced towards the operating medium inlet
point. In these views, short lines intersecting 60
above described, toward the boiler outlet, that vthe tubes indicate flow control or throttling de
is, in this case, toward the separating drum, and vices, the heavy short lines, at t, indicating a
the temperature impulse is taken at a point along throttling or resistance setting of the devices and
the measuring tube within 'the ñnal region of the light lines, at o, an open or non-throttling
the preheating Zone of -the measuring'tube which setting thereof.
overlaps the initial portion ofthe evaporation
Figs'. 2 and 4 show the derivation of the im
Zone of the remaining tubes. In the other meth
od, the measuring tubeis soV arranged and Vsteam
producing media are so supplied thereto that the
initial portion of the superheating zone -thereof
overlaps a portion of the evaporation »Zone ofthe
‘remaining tubes; and, as before, the initial over
lapping portion of the superheating zone of the
measuring tube is used to give 'la temperature
impulse for controlling purposes. The tempera
‘ pulse from a point lying at the end 'or near the
ond of the preheating, the end of the preheating
being displaced with ‘respect to the other tubes
towards the generator outlet. Fig. 5 vshows 'the 70
derivation of the impulse in the case of a steam
generator which 'is fed with an lexcess of water
and in which the excess of water is separated
from the steam in a drum as shown in the draw
As beforefthe resistance or throiítling'setß 75
2, 126,248
ting of the flow control devices is indicated in
each instance by a heavy> cross-line and by the
reference character t and the non-throttling set
tings thereof are indicated by the light cross
lines and the reference character o.
In Figs. 6 and 7, there are shown diagrammatic
` arrangements employing the principle of control
already described; and, in each of these views
there are shown parallel connected tubes I0 and
10 II supplied with feedwater by a pump I2 and
with heat by means of any suitable combustion
apparatus connected generally at I3. Super
heated steam is supplied from the tubes to the
prime mover I5.
The tubes I0 are so arranged and steam-pro
ducing media are so supplied, thereto that the
heating surface is divided into a preheating zone
A, an evaporating zone B, and a superheating
zone C; however, the measuring tube II is ar
ranged, by any suitable means, to have its corre
sponding Zones offset so as to provide regions of
in the measuring tube with respect to the re
maining tubes, any suitable flow control or throt
tling devices being associated with the tubes for
this purpose. In Figs. 1 to '7, inclusive, the throt
tling or resistance setting of these devices is indi 5
cated in each instance by a heavy cross-line and
the reference character t and the non-throttling
setting is indicated by a light cross-line o. Figs.
8 andV 9 show, by wayy of example, iiow control
or throttling devices capable of being placed in
the throttling position, t, or in the non-throttling
or open position o.
In these views, the resistance
or throttling condition, t, is secured by adjusting
the valve 22 so that ñow occurs through the upper
branch of the passage having the orifice 23 While
the open or non-throttling condition is secured
by adjustment of the valve so that ñow occurs
through the lower branch of the passage.
As hereinbefore described, the load effect of the
prime mover may be used to supply a controlling 20
impulse to either or both of the steam-producing
the heating surface thereof, preheatingor super
media, feedwater and heat, supplied to the boiler.
heating, overlapping or falling within the physi
In Figs. 6 and 7, `this impulse is indicated dia
`cal limits of the evaporation zone B, whereby such grammatically as originating with the prime
25 overlapping portion of the measuring tube pro- .
mover governor and going to motors I9 and 20,
vides a region of variable temperature within the whichdetermine or control the operation of the
limits of the evaporation Zone B and which may feed pump and of the fuel and air supply. In
_be used to give a temperature controlling im
addition, the temperature impulse coming from
the device I8 in Fig. 6 is shown as being super
In Fig. 6, by restricting the flow, for example, imposed upon the main impulse in order to exer 30
in the measuring tube II relatively to the flow cise a corrective effect, whereby a desired out
in each of the remaining tubes II), it will be seen going superheated steam temperature may be
that the superheating zone C’ extends further maintained. Inv Fig. 7, instead of the governor
back so that the initial portion b-cV falls within impulse being used to control both the feedwaterA
35 the physical limits of the main evaporation Zone
and the heat supply means, this impulse is
B of the tubes III, and this initial or overlapping exerted only on the feed water supply means,
portion of the measuring tube is, therefore, sub
ject to rise and fall of temperature dependent on
operating conditions and may be used- to provide
40 a temperature impulse for the controlling appa
Any suitable means may be used to secure dif
ferential throttling of flow in the measuring tube
with respect to the remaining tubes. Accord
45 ingly, in Fig. 6, the heavy cross-line I Ii at the left
hand end of the measuring `tube indicates a
greater resistance to fiow therein than through
the remaining tubes I0, the resistance of the
latter being indicated by the relatively light cross
lines I1. In this view, a temperature responsive
device I8 is shown associated with the overlap
ping portion b--c of the measuring tube and pro
vides an impulse for the control system, as will
the temperature responsive device I8’ operating
to control the fuel and air supply means. Ac
cordingly, therefore, so far as the present inven
tion is concerned, it is only essential that the con 40
trol system shall use a temperature impulse and
it is immaterial speciñcally how this impulse is
While I have shown my invention in several
forms, it will be obvious to those skilled in the 45
art that it is not so limited, but is susceptible of
Vvarious other changes and modifications without
departing from the spirit thereof, and I desire,
therefore, that only such limitations shall be
placed thereupon as are imposed by the prior art
or as are speciñcally set forth in the appended
What I claim is:
be immediately pointed out.
1. In a steam generator, a plurality of parallel
55 >Fig. '7 shows a diagrammatic arrangement connected tubes, means for supplying feedwater
which is similar to Fig. 6 except that the resist
as working medium and heat to the tubes so that
ances are reversed, greater flow occurring the Working medium is preheated, vaporized and
through the measuring tube I I than through the superheated in successive Zones; means providing
.remaining tubes II), with the result that the pre
for offsetting of said zones in one tube with re
heating, evaporation, and superheating zones A2, spect to the zones of the remaining tubes, so that
B2, and C2 are displaced toward the outlet, where-- said first tube constitutes a measuring tube,
by there is provided a final portion a--b of the whereby the measuring tube has a region of
preheating Zone A2 which overlaps the initial variable temperature which partially overlaps the
portion ofthe main evaporation zone B, this over
evaporation Zone of said remaining tubes; and
lapping portion a-b of the measuring tube pro
means for deriving a temperature impulse fromv 65
viding a region of heating surface whose tem
said overlapping region of the measuring tube
perature varies dependent upon operating con
and for utilizing the impulse to control said sup
ditions and which falls Within the physical limits ply means.
of the main evaporation zone. ` Accordingly, the
70 temperature responsive device IB’ is associated
2. The combination as claimed in claim 1
wherein the means providing for oifsetting of the
with the overlapping portion a-b and provides zones in the tubes are adjusted so that the initial 70
a temperature impulse for the controlling system. portion of the superheating Zone of the measur
As hereinbefore pointed out, resistance or flow ing tube is overlapped by the ñnal portion of the
control devices are associated withthe various >evaporation Zone of the remaining tubes and
75 tubes soY as to secure a differential ñow effect wherein the means for deriving a temperature
impulse -from the measuring tube is associated
with said overlapped portion thereof. '
3. The combination as claimed ‘inV claim 1
wherein the means providing for oiïsetting the
zones of the tubes are adjusted so that the final
portion of the preheating zone'of the measuring
tube is overlapped by the initial portion of the
evaporation zone of the remaining tubes and
wherein the means for deriving the temperature
impulse from the measuring tube is associated
with said lñnal overlapped preheating portion
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