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Патент USA US3057174

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Oct. 9, 1962
3,057,164
H. B. OPLADEN
STEAM GENERATING UNIT
Filed June 27, 1960
24
8
INVENTOR.
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3,657,164
STEAM GENERATENG UNlT
Heinz iienno Upladen, Worcester, Mass, assiguor to Riley
Stoker Corporation, Worcester, Mass, a corporation of
Massachusetts
Filed June 27, 19%, Ser. No. 38,792
9 (Ilaims. ((11. 60-43)
rC€
3,057,164
Patented Oct. 9, 1962
2
rated at least in part from the pass in which the primary
Ire-heater section 14 is located. The economizer 19 has
a lower portion which extends entirely across the back
pass of the steam generator and an upper portion which
extends only in a passage separated by a baf?e 20 from
the passage in which the primary reheater section 14 lies.
The high-temperature section of the economizer 19 is
provide-d with platens which lie in the upper convection
pass of the steam generating unit and are connected to a
This invention relates to steam generating apparatus,
and more particularly to apparatus arranged to produce l0 collecting header 21 which is connected to a spill-over
valve 22 which will be described more fully hereinafter.
steam for the operation of a turbine-generator set.
The ‘feed water pumps 11 are also connected by a line
It is common practice in power plants to obtain the
to a spray-type desuperheater 23 and the pipe has a spray
energy from steam by passing it through two turbines, one
water control valve 24 connected from the line. A con—
of which is a low-pressure turbine and the other of which
is a high-pressure turbine, and returning the steam to the 15 necting pipe 25 leads from the collecting header 21 to a
steam mixer 26 into which the steam generating tubes in
steam generating unit for reheating between the two stages.
the evaporation zone 28 of the boiler discharge. An auto
It has been suggested that the second stage, which is a
matic check-valve 27 is located in the connecting pipe 25.
low pressure turbine and requires a relatively inexpensive
When the pipe 25 is connected not only with the inlet
construction, be made considerably larger in capacity than
the low-pressure turbine so that it is capable of operating 20 header ‘17 but with the intermediate portion of the evapo
ration zone 28 the upper portion of the evaporation
during high load periods with a considerably greater
zone is connected to the steam mixer 26, the output of
amount of steam ?owing through it than the high-pressure
which is connected to the radiant superheater 29. The
turbine. Since this requires that more steam be returned
output end of this superheater is connected to the ?nal
‘from the reheater portion of the steam generating unit
than originally emerged from the superheater, a consider 25 superheater 30 which is in the form of radiant platens
located in the upper part of the furnace. The ?nal sec
able problem is presented. One way of doing this, of
course, would be to provide a small supplementary steam
tion of reheater tubes are formed as platens 31 which are
also located in the upper part of the furnace. The high
pressure piping 32 leads steam from the furnace super
ment and so on, however, would to a great extent offset 30 heater 30 through a throttle valve 34 to the high-pressure
turbine 35. In a similar manner, pressure piping 33 leads
the savings which prompted one to provide the large
generating unit to provide the low-pressure turbine with
the extra required steam. The added auxiliary equip
capacity low-pressure turbine in the ?rst place. These
and other dif?culties experienced with prior art devices of
this kind have been obviated in a novel manner by the
from the output of the ?nal section of reheater platens 31
to the low-pressure turbine 36, the turbines 35 and 36 be
ing connected in the usual way to an electrical generator
35 37. There is a wattmeter 38 which is connected to pro
present invention.
vide a signal to a fuel controller '39 as Well as a valve
It is, therefore, an outstanding object of the invention
controller 41. A suitable ‘condenser 40 follows the low
to provide a steam generating unit capable of supplying
pressure sections of the turbine in the usual manner and
considerably larger amounts of steam from the reheater
the condensed steam is led to a hot well 42 which is
than ‘from the superheater.
Another object of this invention is the provision of a 110 connected to the inlet sides of the pumps 11. -'I‘he tur
once~through, forced-?ow boiler capable of supplying peak
load steam to a large size, low-pressure turbine operating
with a small size high-pressure turbine.
A further object of the present invention is the provi
sion of a steam generating unit in which the economizer
surfaces are used as a low temperature reheater section
during peak load conditions.
bines are provided with a governor 43 which is connected
in a controlling manner to the throttle valve 34. As is
clear, suitable controls are provided for the pumps ‘11 so
that ?ow is maintained at predetermined rate. In the
same way the flow through the pipe leading to the econ
omizer inlet header 18 and to the steam desuperheater 23
are regulated and maintained in a proper ratio by ori?ce
type flow measuring devices in these pipes which operate
With these and other objects in view, as will be appar
ent to those skilled in the art, the invention resides in the 50 through the control 15 to regulate the valve 13 so that
the amount of water supplied to the desuperheater is in
combination of parts set forth in the speci?cation and
proportion to the amount of water which passes through
covered by the claims appended hereto.
The character of the invention, however, may be best
understood by reference to one of its structural ‘forms as
illustrated by the accompanying drawing in which:
The single FIGURE shows a somewhat schematic
view of a power plant incorporating the principles of the
the forced-flow once-through boiler. The controller 41
receives signals from the spill-over valve 22 which is con
nected between the collecting header 21 and the inlet to
the ?nal section of reheater platens 31; it is connected also
to the wattmeter 38 to receive a signal and to control
the ?ow of water through the throttling valve 16 leading to
present invention.
the inlet header 17. The desuperheater control valve 24
Referring to the drawing, it can be seen that the power
plant, indicated generally by the reference numeral '10‘ 60 is controlled from temperature readings taken in the super
heater piping 32, while the division of flow of gases
is provided with two feed water pumps 11 which are con
through the passes in the backpass of the boiler is regu
nected to force water through a high-pressure pre-heater
lated by dampers under the control of temperature meas
12 which is followed by a feed water regulation valve 13.
urements taken in the reheater piping 33. The fuel con
In the backpass of the steam generating unit associated
troller 39 receives signals from the wattmeter 38 and also
with the power plant is situated a primary reheater sec
from pressure-drop measurements taken around the throt
tion 14. A control 15 is connected to the valve 13 for
tle valve 34 in the conventional manner.
the regulation thereof. A throttling valve 16 is located in
The operation of the apparatus will now be readily
the pipe leading from the valve 13 to an inlet header 17
understood in view of the above description. Feed water
at the lower part of the main furnace of the steam generat
ing unit. Another line leads from the valve 13 to an 70 is supplied by the high-pressure feed Water pumps 11 and,
after passing through the high-pressure preheater 12, the
economizer inlet header 18 associated with the economizer
feed Water enters the economizer inlet header 18, after
of the steam generating unit, which economizer is sepa
3,057,164
passing through the feed water regulation valve 13. After
traveling through the economizer 19 and its hanger tubes,
the water ?ows through tube platens to the collecting
header 21. It then passes through the connecting pipe
A.
Maintenance of both superheated and reheated steam tem
perature is automatically controlled by the control de
scribed in my aforementioned co-pending application.
Now, the steam weight which passes through a steam
25 through the inlet header 17 into the evaporation zone 5 nozzle is determined by the formula:
28. The slightly superheated steam then enters the steam
P
mixer 26 in which steam from parallel circuits will mix
W A><k>< VPX—V
uniformly before entering the radiant superheater 29. The
superheated steam leaves the superheater 29 and flows
where Azthe minimum area of the steam nozzle; k=a
through the spray-type desuperheater 23 to the ?nal super 10 constant for over-critical pressure; P=the initial pressure
heater 30. Steam of the correct temperature and pressure
of the steam; V=the initial speci?c steam volume. Now,
passes through the pipe 32 and the throttle valve 34‘ to
P X V is a constant for all practical purposes, so we
the high~pressure turbine 35.
can then write:
As has been stated above, the reheater consists of two
W=constant><P
sections, a primary section 14 located in a regulating pass 15
That is, the steam pressure entering the turbine nozzle
and a ?nal section of radiant tube platens 31. The steam
returns from the high-pressure turbine 35, ?ows through
the primary reheater section, where its temperature is
controlled by gas ?ow dampers. After receiving its ?nal
temperature in the radiant section 31, the steam enters the 20
low-pressure turbine 36 after traveling through the pipe
33. After passing through the low-pressure turbine 36,
changes linearly with the load.
To operate a boiler with
variable pressure over the entire load range it is not nec
essary to control the turbine with regulating valves.
The turbine speed is determined by the equation:
X constant
the steam is exhausted through the condenser 40‘ and
wherein Ah=enthalpy of steam; W=steam Weight; and
passes into the hot well 42 from which it is fed to the feed
pumps '11.
25 I=electrical energy. When the network calls for more
load, the speed of the turbine generator tends to drop.
A change in fuel input tends to change steam tempera
The generator 37 must maintain a constant speed and,
ture, but steam ‘temperature is maintained at a constant
therefore, the governor '43 of the turbine calls for more
value in the present case by the desuperheater 23 under
steam by its control over the throttle valve 34. It would
the in?uence of the control 24. The steam‘ output of the
unit is controlled by the fuel input. The fuel controller 30 be, of course, possible to send a signal from the governor
43 directly to the fuel input control 39, but the lag in
39 receives its impulse from the wattmeter 38. The
time in using this type of control is prohibitive and for
boiler control maintains a constant ratio of spray water
this reason the throttle valve 34 is placed between the
and feed water ?ow. This control system is the subject
boiler and the turbine. This valve holds a constant pres
of my co-pending patent application Serial No. 38,793
?led June 27, 1960. This constant ratio is, of course, 35 sure drop across itself over the entire load range. If the
governor calls for more steam, this throttle valve 34 opens
maintained by the control 15. The steam temperature
suddenly and pressure and steam weight at the turbine
thus controls both spray water and feed water ?ow.
inlet increases, so that the boiler acts as an accumulator
The present boiler is designed to produce larger quan
and overcomes the delay time of the ?ring equipment.
tities of low-pressure steam than that normally required
It is obvious that minor changes may be made in the
for a conventional single reheat plant, but only during a
form and construction of the invention without departing
period of higher or “peak” demand. For a normal load
from the material spirit thereof. It is not, however, de
condition the boiler performs as a conventional reheat
sired to con?ne the invention to the exact form herein
unit. Under peak load part of the economizer surface
shown and described, but it is desired to include all such
of the boiler is converted to reheater surface, while an
other portion of the initial economizer surface becomes 45 as properly come within the scope claimed.
The invention having been thus described, what is
evaporating surface. When a higher than normal load
claimed as new and desired to secure by Letters Patent is:
demand is encountered, the wattmeter 38 through its con
1. In a power plant having a high-pressure turbine and
nection to the fuel controller 39 calls for increased burn—
a low-pressure turbine having a greater capacity than the
ing rate. The higher rate of furnace heat released tends
to increase the ?nal steam temperature beyond its pre 50 high-pressure turbine, a steam generating unit having an
economizer, an evaporative zone, a superheater, and a
determined value and, because feed water ?ow is con
trolled from steam temperature, an increase in feed Water
reheater, the output end of the reheater being connected
to the low-pressure turbine, feed water lines connected
?ow is automatically called for by an impulse sent to the
to the input end of the economizer and to the evaporative
feed valve 13. The increase in power demand above
normal automatically opens the throttling valve 16 which 55 zone of the unit, a normally-inoperative means connect
ing the output end of the economizer to the input end of
permits a portion of the feed water to flow directly to
the reheater, and means responsive to peak load demand
the evaporating section of the boiler, thus by-passing the
to render the ?rst-named means operative.
evaporation within the economizer. This results in even
2. In a power plant as recited in claim 1, a check valve
tual heating of the steam thus generated in the “econo
mizer” to a predetermined high value; when this tempera 60 located in a line connecting the evaporative zone to the
economizer serving to inhibit ?ow of ?uid from the econ
ture is reached, the spill-over valve 22 permits steam gen
omizer to the evaporative zone when the said normally
erated in the economizer to ?ow into the reheater. This
inoperative means is operative.
‘valve performs as a pressure-reducing valve so that the
3. A steam generating unit for use with a high-pressure
correct predetermined reheater pressure is maintained.
The reheater flow is, thus, increased by the quantity of 65 turbine and a low-pressure turbine, wherein the low-pres
sure turbine has substantially greater capacity than the
steam generated in the upper section of the economizer
and more than normal low pressure steam of the correct
high-pressure turbine, comprising an elongated combus<
temperature is being supplied to the low-pressure section
tion chamber having a lateral convection pass at one end
'of the turbine.
leading to an elongated backpass, a baffle dividing the
The connecting line 25, which normally connects the 70 backpass into two parallel passages, a primary reheater in
economizer with the evaporating zone of the boiler, con
one of the said passages, an economizer in the other of the
said passages, a secondary reheater consisting of radiant
tube platens located at the said one end of the combustion
chamber, the reheaters being connected in series with one
greatly reduced so that the check valve 27 closes to pre
vent feed water from ?owing through this pipe line. 75 another and with the low-pressure turbine, an evapora
tains the automatic check-valve 27. When the spill-over
valve 22 is opened, the pressure within the pipe line 25 is
3,057,164
6
5
arranged on the surfaces of the combustion chamber, feed
water pumps supplying feed water to the economizer and
the combustion chamber, a superheater having radiant
the evaporation zone, valves regulating the division of
tube platens located in the said one end of the combustion
Water between the economizer and the evaporation zone,
chamber, the evaporation zone and the superheater being
a superheater having radiant tube platens located in the
connected in series with one another and with the high
said one end of the combustion chamber, the evapora
pressure turbine, a spillover valve connected between the
tion zone and the superheater being connected in series
output of the economizer and the inlet of the secondary
with one another and with the high~pressure turbine, a
reheater, and a controller for opening the spillover valve
desuperheater located between the evaporation zone and
when the load on the unit exceeds a predetermined value.
4. A once-through, ‘forced-?ow steam generating unit 10 the said radiant tube platens, a valve connected between
the feed water pumps and the desuperheater to regulate
for use with a high-pressure turbine and a low-pressure
the flow of water to the desuperheater, a spillover valve
turbine, wherein the low-pressure turbine has substantially
connected between the outlet of the economizer and the
greater capacity than the high-pressure turbine, comprising
inlet of the secondary reheater, and a controller for open
an elongated combustion chamber having a lateral con
ing the spillover valve when the load on the unit exceeds
vection pass at one end leading to an elongated back-pass,
a predetermined value.
a baf?e dividing the back-pass into two parallel passages,
7. In a power plant having a high-pressure turbine and
a primary reheater in one of the said passages, an econo
a low-pressure turbine having a greater capacity than the
rnizer in the other of the said passages, a secondary re
high-pressure turbine, a once-through, forced-?ow steam
heater consisting of radiant tube platens located at the
said one end of the combustion chamber, the reheaters 20 generating unit having an economizer, an evaporation
zone, a feed water pump supplying feed water to the
being connected in series with one another and with the
economizer and the evaporation zone, valves regulating
low-pressure turbine, an evaporation zone consisting of
the division of water between the economizer and the
tubes arranged on the surfaces of the combustion cham
evaporation zone, a superheater, a reheater, the output
ber, feed water pumps supplying feed water to the econo
mizer and the evaporation zone, valves regulating the di 25 end of the reheater being connected to the low-pressure
turbine, feed water lines connected to the input end of the
vision of water between the economizer and the evapora
economizer and to the evaporation zone of the unit, a
tion zone, a superheater having radiant tube platens locate
normally-inoperative means connecting the output end of
ed in the said one end of the combustion chamber, the
the economizer to the input end of the reheater, and
evaporation zone and the superheater being connected in
series with one another and with the high-pressure turbine, 30 means responsive to peak load demand to render the ?rst
named means operative.
a spillover valve connected between the output of the
8. In a power plant having a high-pressure turbine and
economizer and the inlet of the secondary reheater, and
a low-pressure turbine having a greater capacity than the
a controller for opening the spillover valve when the load
high-pressure turbine, a steam generating unit having an
on the unit exceeds a predetermined value.
5. A steam generating unit ‘for use with a high-pressure 35 economizer, an evaporative zone, a superheater, a re
heater, the output end of the reheater being connected to
turbine and a low-pressure turbine, wherein the low-pres
the low-pressure turbine, feed water lines connected to
sure turbine has substantially greater capacity than the
the input end of the economizer and to the evaporative
high-pressure turbine, comprising an elongated compres
zone of the unit, a desuperheater located between the
sion chamber having a lateral convection pass at one end
leading to an elongated backpass, a ba?le dividing the 40 evaporation zone and the superheater, a valve connected
between a [feed water source and the desuperheater to
backpass into two parallel passages, 21 primary reheater
regulate the flow of water to the desuperheater, a nor
in one of the said passages, an economizer in the other of
mally-inoperative means connecting the output of the eco
the said passages, a secondary reheater consisting of radi
nomizer to the input end of the reheater, and means re
ant tube platens located at the said one end of the combus
tion chamber, the reheaters being connected in series with 45 sponsive to peak load demand to render the ?rst-named
means operative.
one another and with the low-pressure turbine, an evap
9. In a power plant having a high-pressure turbine and
oration zone consisting of tubes arranged on the surfaces
a low-pressure turbine having a greater capacity than the
of the combustion chamber, a superheater having radiant
high-pressure turbine, a once~through, forced ?ow steam
tube platens located in the said one end of the combustion
chamber, the evaporation zone and the superheater being 50 generating unit having an economizer, an evaporation
zone, feed water pumps supplying feed water to the eco
connected in series with one another and with the high
nomizer in the evaporation zone, valves regulating the
pressure turbine, a ‘desuperheater located between the
division of water between the economizer and the evapora
evaporation zone and the said radiant tube platens, a
tion zone, a superheater, a reheater, the output end of the
valve connected between a source of feed water and the
55
desuperheater to regulate the ?ow of water to the desuper
reheater being connected to the low-pressure turbine, feed
water lines connected to the input end of the economizer
heater, a spillover valve connected between the output of
and to the evaporation zone of the unit, a desuperheater
the economizer and the inlet of the secondary reheater,
located between the evaporation zone and the said radiant
and a controller for opening the spillover valve when
tube platens, a valve connected between the feed water
the load on the unit exceeds a predetermined value.
6. A once-through, forced-?ow steam generating unit 60 pumps and the desuperheater to regulate the flow of water
tion zone consisting of tubes arranged on the surfaces of
for use with a high-pressure turbine and a low-pressure
to the desuperheater, a normally-inoperative means con
turbine, wherein the low-pressure turbine has substantially
greater capacity than the high-pressure turbine, compris
ing an elongated compression chamber having a lateral
necting the output end of the economizer to the input end
of the reheater, and means responsive to peak load demand
pass, a baf?e dividing the backpass into two parallel pas
References Cited in the ?le of this patent
UNITED STATES PATENTS
convection pass at one end leading to an elongated back 65
sages, a primary reheater in one of the said passages, an
economizer in the other of the said passages, a secondary
reheater consisting of ‘radiant tube platens located at the
said one end of the combustion chamber, the reheaters be 70
ing connected in series with one another and with the low‘
pressure turbine, an evaporation zone consisting of tubes
to render the ?rst-named means operative.
2,602,433
Kuppenheimer _________ __ July 8, 1952
2,685,280
2,852,005
2,878,791
Blaskowski ____________ __ Aug. 3, 1954
Buri ________________ __ Sept. ‘16, 1958
Lieberherr ___________ __ Mar. 24, 1959
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