U.S. patent number 3,716,305 [Application Number 05/065,677] was granted by the patent office on 1973-02-13 for gas turbine power plant.
This patent grant is currently assigned to Klockner-Humboldt-Deutz Aktiengesellschaft. Invention is credited to Georg Oberlander.
United States Patent |
3,716,305 |
Oberlander |
February 13, 1973 |
GAS TURBINE POWER PLANT
Abstract
The present invention relates to an arrangement of controlling a
compressor station for a gaseous medium in which the compressor
station comprising turbine driven compressors is interposed between
a source of a gaseous medium and a consumer. The compressors have
associated therewith controllable bypass conduit means so that the
gaseous medium coming from the said source can selectively be
passed through said compressors in succession or can bypass at
least some of said compressors.
Inventors: |
Oberlander; Georg
(Bensberg-Frankenforst, DT) |
Assignee: |
Klockner-Humboldt-Deutz
Aktiengesellschaft (Deutz, DT)
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Family
ID: |
7228813 |
Appl.
No.: |
05/065,677 |
Filed: |
August 20, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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622730 |
Mar 13, 1967 |
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Current U.S.
Class: |
417/2; 417/26;
417/47 |
Current CPC
Class: |
F17D
1/07 (20130101) |
Current International
Class: |
F17D
1/07 (20060101); F17D 1/00 (20060101); F04b
041/06 () |
Field of
Search: |
;417/2,47 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Parent Case Text
This is a continuation of application, 622,730 filed Mar. 13, 1967,
now abandoned.
Claims
I claim:
1. The method of controlling the pressure of the gaseous medium in
a main conduit leading from a constant source of gaseous medium at
a substantially constant pressure to a receiver station to maintain
a constant minimum pressure at said receiver station, in which a
compressor station is interposed in said conduit distant from said
receiver station and said source and at which the input pressure
varies with variations in the volume of flow of said gaseous
medium, said compressor station comprising a plurality of
individually speed controllable centrifugal compressors and a
plurality of individually variable speed regulated gas turbines,
each connected to one of said compressors, and individually
controllable bypass circuits associated with said compressors for
bypassing each of said compressors, said method including operating
only the number of turbines and compressors necessary to provide an
output pressure to maintain a substantially constant pressure at
said receiver station while bypassing each inoperative compressor
by a bypass circuit, and varying the output pressure at said
compressor station by operating all but one of the operating
compressors at full capacity and controlling the operation of only
one turbine and its compressor to vary the output pressure in
accordance with the input pressure at said compressor station to
produce an output pressure variable with the volume of flow of said
gaseous medium to maintain a substantially constant pressure at the
receiver station with varying flow of said gaseous medium through
said conduit.
Description
The present invention concerns an arrangement of and a method for
controlling compressor stations for gaseous media using gas
turbines as prime movers which latter serve for compensating for
the pressure drop in the conduits so as to maintain a minimum
pressure at the consumer.
The object of the present invention consists in providing the
arrangement and control of a plant of the above mentioned type, as
used for instance for supplying a pipe line net for natural gas, in
such a way that the driving gas turbines as well as the compressors
during the time period during which the station is only under
partial load, i.e. operates with reduced delivery, will work within
the range of a favorable degree of efficiency and thus will operate
economically.
This object has been realized according to the present invention by
equipping each compressor station with a plurality of sets of
turbocompressors which with regard to the direction of flow are
arranged one behind the other and which can be bridged by bypass
conduit means adapted to be closed. Said turbocompressors are
variable as to speed. The turbocompressors are adapted, when the
delivery drops and the bypass conduits are closed, to be controlled
so that beginning with the last step they are one after the other
reduced as to speed, then by opening the respective associated
bypass conduit are turned off as far as flow is concerned and are
stopped. In view of the arrangement of the sets of compressors in
series, the conditions are created for economically operating the
station when only partial quantities are delivered, i. e. when a
lower output is consumed than at maximum flow, since the delivery
drops rapidly with a reduction in the throughflow.
If, in conformity with the present invention, with dropping
throughflow the speed of the respective last compressor set is
reduced in conformity with the course of the delivery curve, and if
said last mentioned compressor set is eventually bypassed, the
respective still operating gas turbines will operate in the upper
output range and thus within range of a satisfactory degree of
efficiency. Furthermore, due to the fact that always only so many
compressor sets are in operation as is necessary under the
respective circumstances, running time is saved which in its turn
results in longer periods of operation of the compressor sets
between fundamental overhauls.
When designing the control, attention is to be paid to the fact
that with a reduction in the throughflow through the station in
view of the inherent reduction in the flow losses in the conduits,
the pressure drop from the source of the medium to the station and
from the latter to the consumer decreases. This means that with a
partial delivery, the input pressure of the station is higher than
at maximum throughflow and that the station output pressure can be
less than with maximum throughflow. With decreasing throughflow,
also the pressure build-up to be produced by the station will
decrease. More specifically, with partial deliveries, the pressure
build-up is a minimum when the control is so effected that the end
pressure at the consumer maintains the value which it had at
maximum throughflow, or is a maximum if the control is effected for
a constant output pressure of the compressor station. In view of
the buffer effect occurring with variations in the delivery, it is
not advantageous to effect the control to obtain a minimum. On the
other hand, it is disadvantageous to control the effect to a
maximum because in such an instance higher compressor outputs are
required. In practice, it is expedient to go beyond the minimum to
such an extent that the end pressure corresponding to the maximum
throughflow does not drop at the consumer which means that it is
expedient to control for the minimum possible pressure build-up, a
method suggested according to a further development of the present
invention.
To approximate the minimum build-up of the pressure furthermore
results in the advantage that from a certain partial delivery
downward, the starting pressure at the source will suffice to
assure at the consumer the required minimum pressure without
additional pressure build-up at the station.
According to the present invention it is suggested with plants in
which the source pressure is constant to base the control for the
operation of the compressor station on the input pressure at the
compressure station.
It is furthermore advantageous according to a further development
of the invention, to provide identical compressor sets which must
have a sufficiently wide characteristic field. This has the
advantage that the compressor sets can be interexchanged and that
the stocking of replacement parts is less expensive.
The present invention is illustrated by way of example in the
accompanying drawings, in which:
FIG. 1 diagrammatically illustrates a natural gas supply line with
a compressor station having three compressor sets. This figure also
graphically shows the course of the pressure from the natural gas
source to the consumer.
FIG. 2 is a graph illustrating the course of the obtainable fuel
consumption with a compressor station arrangement according to the
invention.
FIG. 3 shows a compressor characteristic field explaining the
operation of the compressor station according to FIG. 1.
Referring now to the drawings in detail, the plant shown in the
upper portion of FIG. 1 comprises a source 1 of natural gas, a
supply line 2 leading to the compressor station, and an output line
4 leading to a storage container 5 to which the consumers are
connected. In the lower portion of FIG. 1, over the flow path S of
the natural gas from source 1 to the storage container 5 there has
been plotted the course of the pressure p. The compressor station 3
has three identical compressor sets each of which comprises a gas
turbine 6, 7 and 8, a turbo-compressor 9, 10 and 11. Flowwise, the
compressors 9, 10 and 11 are arranged in series with regard to each
other and are adapted to be bridged by bypass conduits 15, 16 and
17 respectively which are controlled by shut-off valves 12, 13 and
14. Moreover, all of the compressor sets are controllable
individually as to their speed.
During a maximum throughflow, the source pressure p.sub.1 drops due
to the flow losses in conduit 2 up to the compressor station 3 to
the station input pressure p.sub.2. All compressor sets are in
operation, and the valves 12, 13 and 14 are closed in bypass
conduits 15, 16 and 17. At the said station, a pressure build-up is
effected up to the pressure p.sub.1 which in its turn in the supply
line 4 to the consumer storage container 5 drops to the desired end
value p.sub.2. If now the throughflow drops for instance to such an
extent that the pressure ahead of the station increases to p.sub.3,
according to the present invention, first the compressor 11 is
controlled downwardly as to its speed to such an extent that the
end pressure in conduit 4 does not drop below p.sub.2. Depending on
the reduction in the throughflow, the compressor 11 is bypassed
flowwise by opening the shut-off valve 14, the compressor set is
stopped and, if desired, the next compressor 10 may be controlled
downwardly as to speed.
With regard to the extent to which the pressure build-up is to be
effected in station 3 within the range of partial delivery, there
exists the possibility on one hand always to compress to the
station output pressure p.sub.1. The second possibility consists in
always compressing only so high (in the illustrated example to
p.sub.4) that, taking into consideration the decrease in the flow
losses in conduit 4 as a result of a reduction in the throughflow,
the pressure at the inlet to container 5 will not drop below
p.sub.2. The last mentioned control method has the advantage that
it is more economical than the other method. When controlling for
constant station output pressure, it would be necessary with the
selected example to have the first two compressors run at full
speed and to have the third stage run at reduced speed. If,
however, a pressure build-up is produced according to the second
method, only the first compressor has to run at full speed while
the second compressor is operated at reduced speed and while the
third compressor is stopped completely and bypassed.
FIG. 2 illustrates the course of the fuel consumption. As will be
seen, the fuel consumption B is plotted over the throughflow per
weight. Curve I shows the course of the fuel consumption within the
range of partial delivery and with a pressure build-up for uniform
end pressure at the compressor station. The irregularity of the
curve is due to the successive switching-off and switching-on of
the individual compressor sets. Curve II analogously shows the
course of the fuel consumption when the pressure is built up to a
station output pressure which will assure the minimum admissible
pressure at the consumer end.
FIG. 3 shows a compressor characteristic field in which the
pressure ratio p/p is plotted over the throughflow per volume at
the compressor inlet V.sub.e. The curve P represents the pumping
limit of the compressor. n.sub.1 to n.sub.4 represent the lines of
the same compressor speed, n.sub.1 corresponding to a compressor
speed of 100 percent. Within the said characteristic field, there
are entered the lines of operation of the three serially arranged
compressors. The points a, b, c, d respectively refer to the
operation with uniform starting pressure of the compressor
stations, while the points A, B, C, D refer to operations with a
minimum starting pressure at the station at which the end pressure
at the consumer is still assured. The index 1 always refers only to
compressor 9, while the index 2 refers to the compressor 10, and
the index 3 refers to the compressor 11.
When full throughflow takes place, all three compressors
respectively run within the operational points a.sub.1, A.sub.1 ;
a.sub.2, A.sub.2 ; a.sub.3, A.sub.3. When the throughflow drops to
such an extent that the third stage of the compressor has to be
switched off, the points of operation of the first two compressor
stages are displaced along a line of uniform speed toward the left
to the corresponding points b.sub.1, B.sub.1 ; b.sub.2, B.sub.2,
whereas the operational lines of the third stage drop to up to the
pressure ratio p/p = 1 to which the points b.sub.3, B.sub.3 on the
abscissa correspond. When the throughflow drops further to a level
at which the delivery of a single compressor will suffice, the
operational points of the first compressor stage will displace
themselves accordingly to c.sub.1, C.sub.1, whereas the operational
lines of the second stage drop from b.sub.2, B.sub.2 to a pressure
ratio 1 in conformity with the points c.sub.2, C.sub.2 on the
abscissa. With a further reduction in the throughflow, the
operational lines of the first stage drop from points c.sub.1,
C.sub.1 to the points d.sub.1, D.sub.1.
The illustrated lines of operation show that for the operation with
uniform output pressure of the compressor station, the
characteristic field may be wider than in other cases but will
always be located within still admissible limits. The closer the
approach to the control method at which only one station output
pressure is produced which still suffices to assure the minimum
pressure at the consumers, compressors with narrower and thus with
such characteristic fields can be employed which have a somewhat
higher optimum degree of efficiency. Thus, with the last mentioned
control method, the operation will also on the compressor side take
place in an area of a more favorable degree of efficiency.
It is, of course, to be understood that the present invention, is,
by no means, limited to the particular arrangements shown in the
drawings but also comprises any modifications within the scope of
the appended claims.
* * * * *