Note: Descriptions are shown in the official language in which they were submitted.
S e 18 . 6 . 9 0
TITLE OF THE INVENTION
~ydraullc Safety a~d Re~ulatin~ Sy~tl3m
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention proceeds from a hydraulic
safety and regulating system for the steam feed of a
turbine in accordance with the first part of claim 1.
Discussion of Backqround
~ydraulic safety and regulating systems are
known for the steam feed of a turbine, in which a
safety oil circuit is provided. Power oil, which
ensures actuation of the drives of rapid-action and
steam-regulating valves, is fed in a separate pipeline.
The safety oil circuit ensures that in the case of a
system failure the turbine can be brought into a safe
operating condition. Only as much oil as covers leakage
losse5 in each case is replenished under pressure in
the safety oil circuit. The oil escaping through leaks,
and the power oil leaving the drives are collected in a
return line and led into an oil draining device. A pump
pre~surize~ the oil and conveys it once again out of
the oil draining device into the circulation. The
pressure in the system is monitored by a safety
;- 30 downward-control unit. This safety and regulating
system requires three pipelines, to be precise that for
the power oil, that for the safety oil circuit, and the
return line into the oil draining device.
This three-pipe safety and regulating system
operates reliably. The outlay for building three
pipelines is, however, comparatively high and in
addition the danger of leaks also increases with an
increasing number of pipe connec ionsO
- 2
SUMMARY OF THE INVENTION
- Accordingly, it is the object of this
invention, as defined in the claims, to provide a novel
hydraulic safety and regulating system for the steam
feed of a turbine which is simple to build and in which
the number of possible leakage points is sharply
reduced.
The advantages achieved through the invention
are essentially to be seen in that there is no need to
build a separate pipeline for the safety oil circuit,
as a result of which the numher of possible leakage
points and thus the danger of fire is sharply reduced.
Furthermore, there is the particularly advantageous
effect that in the case of a pressure drop, for example
as a consequence of a pipe fracture, the replenishment
of power oil is suppressed, as a re~ult of which
consequential damage is reduced to a comparatively low
extent. Despite the saving of one pipeline, a
satisfactorily high dynamics of the turbine regulation
is reliably guaranteed in all possible cases of
operation.
The further embodiments of the invention are
the subjects of the dependent claims.
The invention, its further development and the
advantages achievable thereby are explained in more
detail below with reference to the drawings, which
represent only one possible embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention
and many of the attendant advantages thereof will be
readily obtained as the s~me becomes better understood
35 by reference to the following detailed description when
considered in connection with the accompanying
drawings, wherein:
Fig. 1 shows a first embodiment of the invention, and
_ 3 _
Fig. 2 shows a second embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like
reference numerals designate identical or corresponding
parts throughout the several views, Figure 1 shows a
diagrammatic representation of a hydraulic safety and
regulating sy~tem for the steam feed of a turbine 1. A
hot-steam line 2, which can be closed by a steam-
regulating valve 3 or a rapid-action valve 4, leads hot
steam into the turbine 1. For the purpose of its
actuation via a valve spindle 5, the steam-regulating
valve 3 is assigned an actuator 6 having a plate-type
drainage amplifier 7. For the purpose of its actuation
via a valve spindle 8, the rapid-action valve 4 is
assigned a rapid-action drive 9 having a plate-type
drainage amplifier 10.
Oil is collected in an oil draining de~ice 15,
and pressurized from there by means of a pressure-
regulated pump 16, and fed under pressure as power oil
into a line 17. For reasons of redundancy, two pumps 16
are frequently connected in parallel. The line 17 leads
into a connecting valve 18. A line 19 leads ~rom the
connecting valve 18 into a main line 20. ~ranching from
the line 17 is a line 21, which is provided with a
restrictor 21a and ends in a centrally arranged safety
downward-control unit 22. It is perfectly possible to
integrate the function of the restrictor 21a into the
- 30 safety downward-control unit 22. A line 23 returns from
the safety downward-control unit 22 into the oil
draining device 15. Furthermore, the main line 20 ends
in the safety downward-control unit 22. The safety
downward-control unit 22 frequently contains three
hydraulic valves, connected to form a 2-from-3 circuit,
with electromagnetic triggering. It is, however, also
possible for more than three electrohydraulic valves to
be interconn~cted to ~orm an arrangement acting as a
4 2 ~
2-from-~ circuit. Furthermore, it is also possible to
constxuct the safety downward-control unit 22 from
basically different elements, and also to use dif~erent
circuit variants in so doing. In case of need, the
safety downward-control unit 22 controls the pressure
of the power oil in the main line 20 downwards.
A tap line 24 branches from the main line 20 to
the plate-type drainage amplifier 10 interacting with
the rapid-action drive 9. A further tap line 25 leads
to the plate-type drainage amplifier 7. Arranged in
this tap line 25 is a check valve 26 which facilitates
the flow of oil from the plate-type drainage amplifier
7. A further tap line 27 branches from the main line 20
further along. This tap line 27 ends in an
electrohydraulic transducer 28. The electrical
actuation of this transducer 28 is no more represented
than the controller, as a rule electronic, which is
master to this hydraulic safety and regulating system
and is connected to a plant control technology. The
electrohydraulic transducer 28 is connected via a line
29 to the plate-type drainage amplifier 7, which
interacts with the actuator 6. A line 30 connects the
actuator 6 to the rapid-action drive 9 and collects the
oil escaping from the two, which is led back via a
connected line 31 into the oil draining device 15.
~ranching from the line 17 into a pressure-
relief valve 33 is a line 32 which relieves pressure
surges occurring in the line 17 via a line 34 into the
oil draining device 15.
-- 30 The line 17 in Fig. 2 is connected to the main
line 20 via a line 35 parallel to the line 19. The line
35 has a restrictor 36, and it can, moreover, be
completely interrupted by an electromagnetic valve 37.
The line 35 is used here to refill the line 20 instead
of the line 21 in the embodiment in accordance with
Fig. 1, so that here no restrictor is provided in the
line 21. The actuation of the electromagnetic valve 37
i3 triggered by a master plant control technology.
- _ 5 ~ J,~
In both embodiments, the main line 20 leads to
further hydraulic drives (not repre~ented) which are
supplied via further tap lines (likewise not
represented) with power oil under pressure. In both
figures, the main line 20 is represented as a single
circuit from which tap lines branch off. This single-
circuit construction of the main line 20 has the
advantage that the ~ame conditions always apply to all
the hydraulic drives. However, it is also possible to
fan the main line 20 out into subcircuits, in which
case it would be necessary for this fanning out to take
place in the region between the termination of the line
19 and the first tap line 24. Were two subcircuits
provided, one circuit could supply the hydraulic drives
of a plurality of rapid-action and steam-regulating
valve~ via tap lines departing from it, while the other
circuit could supply, for example, actuators for
regulating the bleeding of steam or blow-off valves via
tap lines departing from it. An attendant advantage of
such fanning out is that the hydraulic safety and
regulating system can be structured more clearly for a
comparatively large number of drives.
Closer consideration may firstly be given to
Fig. 1 in order to explain the mode of operation. When
no oil pressure prevails in the main line 20, the
steam-regulating valve 3 is closed together with the
rapid-action valve 4, and the turbine 1 is not supplied
with steam. If, now, the turbine 1 is to be run up to
speed, it is firstly necessary for the main line 20 to 30 be filled with oil under pressure. During this process,
the pump 16 feeds oil under pressure through the line
17, the line 21 and the safety downward-control unit 22
into the main line 20, and refills the latter. The
restrictor 2la limits the flow of oil such that no
pressure surges can occur in the main line 20 and the
connected tap lines 24, 27. Should air still be present
in the main line 20 and in the associated tap lines 24,
27, this air passes through leakage points in the
hydraulically driven devices into the lines 30 and 31
and, finally, into the oil draining device 15, from
which it can escape from the system. During this
process, the connecting valve 18 shuts off the line 17.
Not until hal~ the operating pressure has been reached
in the main line 20 can the connecting valve 18,
supported by this half the operating pressure present
in the line 19, open and take over the oil
replenishment. In normal operation, the oil
replenishme~t takes place permanently through the
connecting valve 18 which permanently releases a
comparatively large crosi-section without restrictor
points. Alongside this, the amount of oil flowing
through the line 21, which is, after all, strongly
limited by the restrictor 21a, is negligible.
Once half the operating pressure has been
reached in the main line 20, the rapid~action drive 9
is actuated via the plate-type drainage amplifier 10,
and the rapid-action valve 4 is opened and remains
permanently open in normal operation. The actuator ~ is
not activated until the electrohydraulic transducer 28
receives an electrical signal from the master plant
control technology and thereupon releases a path for
the power oil to flow through under pressure from the
tap line 27 into the line 29 and on from there into the
plate-type drainage amplifier 7. As a rule, the master
plant control technology will not release this signal
until total operating pressure has been reached in the
main line 20. The power oil flows on from the plate-
type drainage amplifier 7 into the actuator 6, and setsthe latter moving in the opening direction. The steam-
regulating valve 3 is likewise opened with this
movement, and steam begins to flow through the hot-
steam line 2 into the turbine 1, and sets the latter
moving. As soon as the prescribed desired value of the
amount o~ flowing steam is reached, the plant control
technology controls the electrohydraulic transducer 28
such that the amount of power oil flowing through is no
-- 7
longer increased and the pressure in the actuator 6 is
held approximately constant. Only small deviations from
the desired value are compensated in this operating
condition. The oil escaping from the actuator 6 passes
together with the oil escaping from the rapid-action
drive 9 into the line 30 and is led back through the
line 31 connected with the latter into the oil draininq
device. From there~ the oil passes b~ck once again via
the pump 16 and the connecting valve 18 into the main
line 20 and`thus into the circulation.
If, in the region of the main line 20 or in the
devices supplied through the latter with power oil
under pressure, an impermissible leak occurs through
which oil escapes, the pressure in the main line 20
falls immediately. As a consequence, the connecting
valve 18 closes simultaneously and the oil
replenishment is interrupted.
Due to the pressure drop in the main line 20, a
pres~ure gradient is also produced in the tap line 25,
~the check valve 26 opens and oil flows off from the
plate-type drainage amplifier 7, as a result of which a
rapid closing movement is triggered in the actuator 6,
so that the steam-regulating valve 3 likewise closes.
This closing process of the actuator 6 takes place
independently of the electrohydraulic transducer 28. In
this process, the oil from the drive of the actuator 6
flows off through the lines 30 and 31 into the oil
draining device 15.
The pressure drop in the main line 20 also acts
via the line 24 on the plate-type drainage amplifiex
10, which trigger~ a rapid response of the rapid~action
drive 9, and thus a rapid closure of the rapid-action
valve 4. The oil situated in the rapid-action drive 9
flow~ off through the lines 30 and 31 into the oil
draining device 15.
The embodiment in accordance with Fig. 2
differ~ in the region of the oil feed from the
embodiment described 50 far. The refilling of the main
2 ~
-- 8 --
line 20 takes place through the line 35; here, the line
21 has the function only of supplying the safety
downward-control unit 22 with power oil, in order in
this way to ensure a satisfactory excess of power
during actuation of the electrohydraulic valves
operating in this unit. In this process, the restrictor
36 limits the amount of oil flowing in, so that no
pressure surges can occur in the main line 20. The
electromagnetic valve 37 is open during the entire
filling process. As soon as half the operating pressure
has been reached in the main line 20, the connecting
valve 18, supported by the pressure in the main line
20, opens in this embodiment, as well, and takes over
the rest of the refilling. The electromagnetic valve 37
thereafter shuts of the line 35 and remains
permanently closed in normal operation. The entire
replenishment of the power oil into the main line 20
takes place through the connecting valve 18 and the
line 19, as already described, so that here, too, the
connecting valve 18 immediately blocks the oil
replenishment in the case of a pressure drop in the
region of the main line. Here, too, it is advantageous
that in this case no oil additionally passe~ into the
main line 20, as a result of which only an escape of
oil that is strictly limited in amount is possible in
the region of a leakage point. In this embodiment as
well, pressure surges occurring during downward control
of the connecting valve 18 are relieved by the
pressure-relief valve 33 into the oil draining device
:- 30 15.
In the case of such an emergency shutdown, the
fact that the oil replenishment is automatically
interrupted immediately after the first indication of
damage, that is to say after the pressure drop, is a
particularly advantageous effect, so that only a little
oil can escape from the lsakage point. This
substantially reduce3 the danger of fire in the region
around the hot turbine 1~ In addition, the danger of
.. . . .
consequential damage due to further uncontrolled escape
of oil is also avoided.
Where the turbine ] is closed down for
operational reasons, the actuator 6 is moved in a
controlled fashion in the closing direction with the
aid of the electrohydraulic transducer 28, until the
steam-regulating valve 3 is closed. The system can
remain in this operating condition if it is necessary
to reckon with starting up the turbine 1 soon. If,
however, the turbine 1 is to be shut down, after
closure of the steam-regulating valve 3 by an
electrical command, which is fed in from the plant
control technology, the safety downward-control unit 22
is excited and as a result the main line 20 is relieved
of pressure via the line 23. The pump 16 is also shut
down by the same electrical command. In this case, as
well, at the moment of pressure relief the connecting
valve 18 immediately blocks the oil replenishment into
the main line 200
The safety downward-control unit 22 ensures
that the turbine 1 can be run down into a controlled
operating condition even in the case of a failure of
the electrical power supply. Consequently, the
hydraulic safety and regulating system in accordance
with the present invention operates absolutely reliably
both in the case of hydraulic breakdowns and in the
ca6e of breakdowns in the electrical sphere. In
addition, this system is also economically
advantageous, since a separate safety oil system can be
-- 30 saved without, however, having to renounce the
advantages of this safety oil system with regard to
increased operating safety. In this hydraulic safety
and regulating system the safety downward-control unit
22 operates in exactly the same way as it would if it
had to monitor a separate safety oil circuit.
Obviously, numerous modifications and
variations of the present invention are possible in
light of the above teachings. It is therefore to he
- 10 - 2~
understood that within the scope of the appended
claim~, the invention may be practised otherwise than
as specifically described herein.
