U.S. patent application number 11/021059 was filed with the patent office on 2005-08-04 for condenser.
Invention is credited to Schaefer, Hermanus Gerardus.
Application Number | 20050167093 11/021059 |
Document ID | / |
Family ID | 34545954 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050167093 |
Kind Code |
A1 |
Schaefer, Hermanus
Gerardus |
August 4, 2005 |
Condenser
Abstract
A condenser, comprising a steam inlet and an exhaust chamber
which are connected via a plurality of cooling tubes connected in
parallel, which exhaust chamber is provided with an exhaust opening
which is connected to a pump, wherein the condenser is provided
with a supplemental barrier to screen the pump during use from
steam breaking through a cooling tube, as well as to screen the
other cooling tubes from steam from a cooling tube subject to steam
breakthrough. A method for condensing steam in a cooler, wherein by
means of a pump a pressure is maintained in the cooler, and wherein
the inert gas discharge is screened from steam breaking through the
cooler.
Inventors: |
Schaefer, Hermanus Gerardus;
(Amersfoort, NL) |
Correspondence
Address: |
QUARLES & BRADY LLP
411 E. WISCONSIN AVENUE
SUITE 2040
MILWAUKEE
WI
53202-4497
US
|
Family ID: |
34545954 |
Appl. No.: |
11/021059 |
Filed: |
December 22, 2004 |
Current U.S.
Class: |
165/300 ;
165/101; 165/120 |
Current CPC
Class: |
F28B 1/06 20130101; F28B
9/10 20130101; F28B 11/00 20130101 |
Class at
Publication: |
165/300 ;
165/120; 165/101 |
International
Class: |
F28F 027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2003 |
NL |
1025109 |
Claims
1. A condenser, comprising a steam inlet and an exhaust chamber
which are connected with each other via a plurality of cooling
tubes connected in parallel, which exhaust chamber is provided with
an exhaust opening which is connected to a pump for discharging
inert gas, wherein the condenser is provided with a supplemental
barrier to screen the pump during use from steam breaking through a
cooling tube.
2. A condenser according to claim 1, wherein the supplemental
barrier is designed as a flow resistance.
3. A condenser according to claim 1, wherein the supplemental
barrier is placed upstream of the pump and, while leaving clear at
least one suction route from steam inlet to pump, at least partly
closes off at least one other suction route from steam inlet to
pump.
4. A condenser according to claim 2, wherein the flow resistance
comprises a restrictor.
5. A condenser according to claim 2, wherein the flow resistance
comprises a variable valve.
6. A condenser according to claim 5, wherein the flow resistance
comprises a thermal valve which hampers the throughflow when a
predetermined temperature of the passing medium is exceeded.
7. A condenser according to claim 1, wherein the cooling tubes are
divided into groups and terminates per group in a separate exhaust
chamber.
8. A condenser according to claim 7, wherein the exhaust chambers
are each provided with their own pump.
9. A condenser according to claim 7, wherein several exhaust
chambers are connected with the same pump.
10. A condenser according to claim 9, wherein between each exhaust
chamber and pump, a separate exhaust line is present in which a
flow resistance is included for screening the pump from steam
breaking through.
11. A method for condensing steam in a cooler, wherein by means of
a pump, through discharge of inert gas, a low pressure is
maintained in the cooler, and wherein the pump is screened from
steam breaking through the cooler.
12. A method according to claim 11, wherein the pump is screened in
that, upon steam breakthrough, while leaving clear at least one
suction route between steam inlet and pump, at least one other
suction route between steam inlet and pump is closed off.
13. A method for condensing steam in a cooler, said method
comprising: pumping an inert gas using a pump to maintain a low
pressure in the cooler; and screening the pump from steam breaking
through the cooler.
14. A method according to claim 13, wherein screening the pump
includes providing at least one open suction route between a steam
inlet and the pump, and closing off at least one other suction
route between the steam inlet and the pump.
Description
[0001] The invention relates to a condenser, in particular a vacuum
condenser for condensing expanded steam from a steam turbine.
[0002] Such a condenser is generally known and comprises a steam
inlet and an exhaust chamber which are connected with each other
via a plurality of cooling tubes connected in parallel, which
exhaust chamber is provided with an exhaust opening which is
connected to a pump for discharging inert gas, for instance a
vacuum pump.
[0003] During use, the steam inlet is connected to the exit of a
steam turbine, so that steam expanded in the steam turbine is
conducted via the steam inlet into the cooling tubes. Through
circumfluence, for instance with a flow of ambient air which may or
may not be forced, the cooling tubes, which are typically provided
with cooling fins, are cooled. The cooling capacity of the cooling
tubes and the flow rate of the circumfluent air have been chosen
such that the steam condenses in the cooling tubes, so that in the
part of the cooling tube contiguous to the exhaust chamber, and in
the exhaust chamber itself, a lower pressure, typically a reduced
pressure, is created. With the aid of this lower pressure, the exit
pressure of the steam turbine can be maintained. By lowering this
pressure, the efficiency of the steam turbine can be increased. The
cooling tubes are conventionally arranged at a slope, for instance
in an A-frame, so that the condensation can flow downwards under
the influence of gravity. To maintain the lower pressure in the
exhaust chamber, gas that does not condense in the condenser, here
also designated as inert gas, such as any leakage air, is
discharged via a pump.
[0004] In practice, a condenser has been found in some cases not to
provide the desired low pressure, which adversely affects the
efficiency of the steam turbine. The fact that the desired low
pressure in the exhaust chamber is condenser or the connection
between turbine and condenser, or to insufficient discharge
capacity of this leakage air. In practice, it has already occurred
a number of times that after fruitless attempts to find the cause,
users have resigned themselves to the fact that in practical
situations the desired pressure in a particular installation
sometimes cannot be attained.
[0005] The object of the invention is to provide a condenser, in
particular a vacuum condenser for a steam turbine, with which,
while maintaining the advantages mentioned, the disadvantages
mentioned can be avoided. To that end, the invention provides a
condenser, comprising a steam inlet and an exhaust chamber which
are connected with each other via a plurality of cooling tubes
connected in parallel, which exhaust chamber is provided with an
exhaust opening which is connected to a pump for discharging inert
gas, wherein the condenser is provided with a supplemental barrier
to screen the pump during use from steam breaking through a cooling
tube.
[0006] With the aid of such a supplemental barrier, in practice the
desired low pressure in the exhaust chamber can be realized with a
greater amount of certainty. The invention is based on the insight
that in many cases where the inert gas, such as leakage air,
accumulates in the exhaust chamber, it is not the magnitude of the
leakage or the design of the condenser that is the causative factor
of the desired pressure in the exhaust chamber not being achieved,
but that as a result of local disturbance of the cooling action, in
one or more cooling tubes steam breakthrough can occur whereas this
would not be expected having regard to the ample capacity of the
whole cooling system. The local disturbance of the cooling capacity
can for instance be caused by fouling of the cooling fins on one of
the cooling tubes and/or through local impediment of the
throughflow of the cooling air. Such local impediment can for
instance be the result of a disturbing sidewind load. When
presently, besides the primary measures against breakthrough of
steam through the cooling tubes, constituted by the amply
dimensioned capacity of the cooling tubes of the condenser,
additionally a supplemental barrier against steam breakthrough is
included, with which the pump during use can be screened at least
partly from steam breaking through a cooling tube, the pump
typically has a sufficient flow rate to exhaust the leakage air
from the exhaust chamber and the desired low pressure can be
preserved in the exhaust chamber of the condenser.
[0007] The supplemental barrier can for instance be designed as a
flow resistance which can screen the pump from steam breaking
through. Such a flow resistance is preferably placed upstream of
the pump and, while leaving clear at least one suction route from
steam inlet to pump, closes off at least partly at least one other
suction route from steam inlet to pump.
[0008] The barrier does not need to fully prevent steam breaking
through, but at least reduces the amount of steam breaking through,
so that the pump can fulfill its task longer. The leakage air from
pipes not breaking through will be discharged, so that these pipes
can fulfill their function. The barrier can be so dimensioned as to
entail hardly any pressure drop when only a small amount of leakage
air passes, but to give rise to an inhibitory action in case of a
larger amount of steam breaking through. This may already be
involved in the use in the case of fixed restrictions, such as a
restrictor having a fixed passage. Also, such a flow resistance can
be designed as a variable valve, for instance a restrictor which
impedes the throughflow when a predetermined flow rate is exceeded,
or a thermal valve which impedes the throughflow when a
predetermined temperature of the passing medium is exceeded. Such a
thermal valve is preferably arranged adjacent an exhaust chamber,
for instance in the part of a cooling tube contiguous to the
exhaust chamber, or in a part of the exhaust line to the pump that
is contiguous to the exhaust opening.
[0009] It is noted that different suction routes can already be
formed by dividing the cooling tubes into groups and having them
terminate per group in a separate exhaust chamber. Such an exhaust
chamber can in each case be provided with its own pump. In such a
case, the supplemental barrier is formed in that the split into
groups has a mutual barrier action; the restriction is then formed
by a multiple steam discharge.
[0010] Preferably, however, several exhaust chambers are connected
with the same pump. In such an arrangement, a separate exhaust line
is present between each exhaust chamber and the pump, while in each
exhaust line a flow resistance is included for screening the pump
from steam breaking through. In this embodiment, through proper
subdivision of the cooler pipes into groups, the disturbing action
of, for instance, a sidewind load can be controlled optimally.
[0011] The invention relates to a method for condensing steam in a
cooler, wherein by means of a pump, through discharge of inert gas,
a low pressure is maintained in the cooler, and wherein the pump is
screened from steam breaking through the cooler. Preferably, the
pump is then screened in that, while leaving clear at least one
suction route between steam inlet and pump, at least one other
suction route between steam inlet and pump is closed.
[0012] Further advantageous embodiments are represented in the
dependent claims.
[0013] The invention will be further elucidated on the basis of an
exemplary embodiment which is represented in a drawing. In the
drawing:
[0014] FIG. 1 shows a schematic side elevation of a first variant
of a condenser according to the invention;
[0015] FIG. 2 shows a schematic side elevation of a second variant
of a condenser according to the invention;
[0016] FIG. 3 shows a schematic side elevation of a third variant
of a condenser according to the invention.
[0017] In the figures, the same or corresponding parts are
indicated by the same reference numerals. The figures are only
schematic representations of preferred embodiments of the invention
and are only given by way of non-limiting exemplary embodiment.
[0018] FIG. 1 shows a condenser 1 with a so-called A-frame 2 which
is arranged at some height above ground level 3, for instance next
to a power plant and in close proximity to the exit of a steam
turbine. The condenser 1 is provided with two steam inlets 4a, 4b
which are each connected, via a series of cooling tubes 5a, 5b
placed at a slope, with an exhaust chamber 6. In this exemplary
embodiment, the inclined cooling tubes 5 leaning towards each other
give the frame 2 of the condenser 1 the shape of an "A" in side
elevation. Arranged at the bottom of the frame 2, between two steam
inlets 4a, 4b, are one or more fans 7. By means of the fans 7,
ambient air, as represented in the figure, can be drawn in from
below and be blown out via the inside of the frame between the
cooling tubes 5. In this exemplary embodiment, the cooling tubes
5a, 5b are provided at their outer circumference with fins to
enlarge their cooling capacity. If the condenser 1 works correctly,
a steam plume 8 passes via the steam inlet 4 into the cooling tube
5, where the steam plume 8, as a result of the cooling, thereby
creating a reduced pressure or "vacuum", has condensed in the upper
part of the cooling tube 5. This is represented in the right-hand
portion of the condenser of FIG. 1. In the figure, the pressure is
symbolically represented by 9. This low pressure provides for the
suction of new steam from the inlet and thus maintains a low
pressure at the turbine exit. As a result of the inclined
arrangement of the cooling tubes 5, the condensate 10 flows down
and is discharged from the lowermost point of the condenser 1,
optionally to a condensate vessel.
[0019] Optionally, prior to the condensation process, inert gas,
such as leakage air, is discharged via an air exhaust line which is
connected via an opening with the central exhaust chamber 6, here a
vacuum chamber, by means of a vacuum pump.
[0020] Should the cooling capacity be insufficient, however, for
instance as a result of a wind load and/or local fouling, steam
breakthrough can occur. This is shown in the left-hand portion of
FIG. 1.
[0021] In the left-hand portion of FIG. 1, it is shown that owing
to locally insufficient cooling capacity, steam breakthrough
occurs. The steam is insufficiently cooled in the cooling tube 5a
and can break through the cooling tube, into the exhaust chamber
6.
[0022] In this case, steam would be discharged from the exhaust
chamber 6 via the line 12 to the pump 13. This pump in turn, due to
the large volume supply of steam, will no longer be able to provide
for a correct discharge of leakage air. The desired pressure then
would not be achieved anymore. However, the condenser 1 is provided
with a supplemental barrier 14 to screen the pump 13 during use
from steam breaking through a cooling tube.
[0023] In this exemplary embodiment, the supplemental barrier is
designed as a flow resistance placed upstream of the pump 13,
which, while leaving clear one suction route between steam inlet 4B
and pump 13, wholly or partly closes off one or a plurality of
other suction routes. In this exemplary embodiment, the flow
resistance is implemented in that each of the cooling tubes 5 is
provided with a thermal valve which closes the cooling tube wholly
or partly when steam flows through the valve. The thermal valves
are arranged at the top of the cooling tubes 5, at a point which is
cool and not exposed to steam during normal functioning of the
cooler. The thermal valves are arranged in an exit part of the
cooling tubes 5, contiguous to the central exhaust chamber 6.
Alternatively, a moisture sensor may be provided, for instance an
electrical contact, with which a valve is driven. In the
arrangement represented here, upon steam breakthrough, each cooling
tube can be individually closed. Likewise as an alternative, fixed
restrictions are possible, which, by virtue of their dimensioning,
hardly cause a pressure drop upon passage of a small flow of
leakage air, but cause a considerable pressure drop upon a greater
flow of leakage air.
[0024] In FIG. 2, an alternative embodiment is shown, in which two
separate exhaust chambers 6a, 6b are provided. The exhaust chambers
are each connected via a separate exhaust line 12A, 12B with the
same pump 13. In each line, a thermostatic valve 14A, 14B is
included. In this exemplary embodiment, cooling tube 5A breaks
through and the valve 14A, through restriction or at least partial
closure of the suction route 4A-5A-6A-12A, screens the pump 13
while leaving clear the suction route 4B-5B-6B-12B-13.
[0025] FIG. 3 shows a variant of the invention, in which the
condenser is provided with separate exhaust chambers 6A, 6B, each
connected with a separate pump 13A, 13B.
[0026] In the embodiment represented here, the A-frame has been
placed on end and there is a central steam inlet 4.
[0027] It is noted that here with an arrangement whereby the air is
sucked along the cooling tubes 5 from the outside to the inside of
the frame 2, a wind load, if any, does not reduce the cooling
capacity.
[0028] In this configuration, a sidewind load, instead of having a
negative influence, has a positive influence on the amount of
cooling air flowing along the cooling tubes on the weather
side.
[0029] Due to the invention, this can be utilized advantageously,
since breakthrough of steam from the lee side pipes is
prevented.
[0030] It will be clear that the invention is not limited to the
preferred embodiments represented here. Thus, the condenser 1 can
for instance be designed as a half "A", with the cooling tubes
situated in one plane surface placed at an inclination. Further, it
will be clear that the shape and construction of the condenser, if
desired, can be chosen differently, for instance with helically or
spirally extending tubes placed horizontally, vertically or at an
inclination, with or without joint steam inlets or exhaust
chambers. Furthermore, instead of valves having a variable passage,
for instance restrictors having a fixed passage can be
employed.
[0031] Such variants will be clear to the skilled person and are
understood to fall within the scope of the invention as set forth
in the following claims.
* * * * *