U.S. patent application number 13/139062 was filed with the patent office on 2011-10-06 for power plant comprising a turbine unit and a generator.
Invention is credited to Volker Amedick, Malte Blomeyer, Leandro Cravero, Eberhard Deuker, Hendrik Heitfeld, Carsten Kaufmann, Meinolf Klocke, Stefan Volker.
Application Number | 20110239650 13/139062 |
Document ID | / |
Family ID | 40846423 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239650 |
Kind Code |
A1 |
Amedick; Volker ; et
al. |
October 6, 2011 |
POWER PLANT COMPRISING A TURBINE UNIT AND A GENERATOR
Abstract
A power plant including a turbine unit having a turbine, a
generator connected to the turbine for power transmission, and a
cooling device for cooling the generator is provided. The cooling
device is provided to release waste heat from the generator to a
device of the power plant. Waste heat may be used in the power
plant process, thus attaining increased efficiency.
Inventors: |
Amedick; Volker; (Duisburg,
DE) ; Blomeyer; Malte; (Mulheim an der Ruhr, DE)
; Cravero; Leandro; (Mulheim an der Ruhr, DE) ;
Deuker; Eberhard; (Mulheim an der Ruhr, DE) ;
Heitfeld; Hendrik; (Gladbeck, DE) ; Kaufmann;
Carsten; (Mulheim a.d. Ruhr, DE) ; Klocke;
Meinolf; (Witten, DE) ; Volker; Stefan;
(Moers, DE) |
Family ID: |
40846423 |
Appl. No.: |
13/139062 |
Filed: |
November 18, 2009 |
PCT Filed: |
November 18, 2009 |
PCT NO: |
PCT/EP09/65374 |
371 Date: |
June 10, 2011 |
Current U.S.
Class: |
60/670 |
Current CPC
Class: |
F01D 15/10 20130101;
F01D 25/12 20130101; F02C 7/224 20130101; Y02E 20/16 20130101; F05D
2260/20 20130101; F05D 2260/234 20130101; F02C 7/08 20130101; F05D
2220/64 20130101 |
Class at
Publication: |
60/670 |
International
Class: |
F01K 23/06 20060101
F01K023/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2008 |
EP |
08021764.9 |
Claims
1. A power plant (2, 44) comprising a turbine unit (4) having a
turbine (10), a generator (24) connected to the turbine (10) for
power transmission and a cooling device (30, 36) for cooling the
generator (24), characterized in that the cooling device (30, 36)
is provided for releasing waste heat from the generator (24) to a
device of the power plant (2, 44).
2. The power plant (2) as claimed in claim 1, characterized in that
the turbine unit (4) includes a fuel preheater (20) which is
thermally connected to the cooling device (30).
3. The power plant (2) as claimed in claim 2, characterized in that
the fuel preheater (20) has a heat exchanger which is thermally
connected to a cooling circuit (26) of the cooling device (30).
4. The power plant (2) as claimed in one of the preceding claims,
characterized in a fuel feed (18) to the turbine (10) is routed
through the generator (24) for heating the fuel.
5. The power plant (2, 44) as claimed in one of the preceding
claims, characterized in that the turbine unit (4) has an air feed
(14) which is thermally connected to the cooling device (30,
36).
6. The power plant (2, 44) as claimed in one of the preceding
claims, characterized by a control means (34) for controlling a
supply of heat from the generator (24) to an air feed (14) of the
turbine unit (4), depending on a danger of icing up of the air feed
(14).
7. The power plant (2, 44) as claimed in one of the preceding
claims, characterized in that the cooling device (30, 36) has an
open cooling circuit and a cooling air feed to an air feed (14) of
the turbine unit (4).
8. The power plant (2) as claimed in one of the preceding claims,
characterized in that the turbine unit (4) has an air preheater
which is thermally connected in a cooler stage to the cooling
device (30) and in a warmer stage to a flue gas feed.
9. The power plant (44) as claimed in one of the preceding claims,
characterized in that the cooling device (36) is thermally
connected to a feed water circuit (50) of the turbine unit (4).
10. The power plant (44) as claimed in one of the preceding claims,
characterized in that the cooling device (36) includes a cooling
water circuit which is part of a feed water circuit (50) of the
turbine unit (4).
11. The power plant (2) as claimed in one of the preceding claims,
characterized in that the cooling device (30, 36) is thermally
connected to a building heating system of the power plant (2).
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2009/065374, filed Nov. 18, 2009 and claims
the benefit thereof. The International Application claims the
benefits of European Patent Office application No. 08021764.9 EP
filed Dec. 15, 2008. All of the applications are incorporated by
reference herein in their entirety.
FIELD OF INVENTION
[0002] The invention relates to a power plant comprising a turbine
unit having a turbine, a generator connected to the turbine for
power transmission and a cooling device for cooling the
generator.
BACKGROUND OF INVENTION
[0003] Various power plant systems are known in which primary
energy is converted by means of a generator into electrical energy.
In these power plants the heat of a heat generator is generally
used to drive a thermal power machine which is connected
mechanically to the generator. Both in the conversion of thermal
energy into mechanical energy in the primary energy generator, for
example a turbine, and also of the mechanical energy into
electrical energy in the generator the respective available energy
is not completely utilized. Residual energy--usually in the form of
heat--is released into the environment.
[0004] In a generator this heat is usually taken away by a cooling
medium, e.g. in a closed circuit, in order to prevent overheating
of the generator. Since this heat is present at a low temperature
level, usually below 100.degree. C., this heat is released unused
into the environment and is thus lost to the power plant
process.
SUMMARY OF INVENTION
[0005] An object of the invention is to specify a power plant with
a higher level of efficiency.
[0006] This object is achieved by a power plant of the type stated
above, in which the cooling device is provided in accordance with
the invention to release waste heat from the generator to a device
of the power plant. The feeding back of waste heat into the power
plant process means that it is not removed from the power plant
process and is thus not a loss. The efficiency of the power plant
can be increased in this way by the proportion of heat fed back
into the working process. The turbine can be a gas turbine or a
steam turbine.
[0007] Through the use of the generator waste heat in a power plant
with a steam turbine for example either the maximum temperature of
the steam of the turbine unit embodied as a steam turbine can be
increased or the mass flow through the steam turbine can be
increased. For a gas and steam turbine block with a total power of
400 to 500 MW the following picture typically emerges: the heat
losses created by the generator range between 3 and 5 MW, of which
around 2 to 4 MW can be fed back as a power increase into the gas
and steam process or into a steam process. With a feed water mass
flow of around 80 kg per second and 3 MW fed back generator power
loss a temperature increase of around 10.degree. C. is produced in
the feed water. With an overall output of 400 to 500 MW this
corresponds to a power increase of around 0.5%. With pure steam
power processes this allows the quantity of steam which is used for
preheating the feed water and which is thus no longer available for
generating energy to be reduced.
[0008] In an advantageous form of embodiment of the invention the
turbine unit includes a fuel preheater which is thermally connected
to the cooling device. The output of waste heat from the generator
to the fuel preheater enables the quantity of primary energy which
would otherwise have to be supplied to the fuel preheater to be
reduced accordingly. The driving force for the feedback is the
temperature difference, since the heat can only be transferred to a
medium that has a lower temperature than the waste heat of the
generator. This usually applies to the fuel of a fossil-fuel power
plant, which is at about ambient temperature. Gaseous or fluid
fuels in particular can be preheated in a technically simple manner
via a heat circuit. Such fuels are especially used in gas turbines.
The preheating of the fuel reduces the necessary quantity of fuel
for achieving the upper process temperature in the thermodynamic
circulation process, whereby its efficiency is increased.
[0009] Advantageously the fuel preheater has a heat exchanger which
is thermally connected to a cooling water circuit of the cooling
device. For safety reasons fuels may only be combined with a
non-oxidizing medium in a heat exchanger in order to avoid
combustible mixtures in the event of leakages. The waste heat of
the generator is predominantly taken away from the generator via a
water circuit. Fuels can be preheated by a heat exchanger in the
water circuit without an oxidizing medium coming into contact with
the fuel in the event of a leak. If hydrogen is used example for
direct cooling of the generator, the outer water circuit can be
replaced by the fuel preheater.
[0010] It is also proposed that a fuel feed to the turbine is
advantageously routed through the generator for heating of the
fuel. The fuel can assume the function of the cooling medium in the
generator so that a separate circuit for removing heat from the
generator, for example a water circuit, can be dispensed with.
[0011] In a further advantageous embodiment of the invention the
turbine unit includes an air feed which is thermally connected to
the cooling device. The entry temperature of fresh air which enters
into a compressor of a gas turbine is that of the environment. It
can thus accept waste heat from the generator. This enables the
thermal efficiency of the power plant to be increased.
[0012] In the part load range in a combined cycle gas and steam
power plant the overall efficiency is increased for fixed power if
the compressor entry temperature is increased. If in this power
range the generator waste heat is used for this purpose, a
corresponding increase in the thermodynamic efficiency of the power
plant is achieved. The feeding of the waste heat to the fresh air
can be undertaken by a heat exchanger in the air feed or by the air
feed being routed through the generator.
[0013] Advantageously the power plant includes a control means for
controlling a heat feed from the generator to a power plant device.
The device can be the air feed of the turbine unit for example. In
particular the control means is provided for controlling the heat
feed as a function of a danger of icing of the air supply. With
ambient temperatures close to freezing point and high air humidity
air can be heated up before entering the compressor in order to
avoid ice formation which can result in damage to components. For
this purpose compressed and thereby heated air is fed back to the
compressor unit, which adversely affects the efficiency of the
compressor. If the waste heat of the generator is used instead, the
compressor efficiency remains unaffected and a higher level of
efficiency can be advantageously achieved. The control of the
control medium can comprise a closed loop process. The probability
of icing up can be referred to as danger of icing.
[0014] In a further advantageous form of embodiment of the
invention the cooling device has an open cooling circuit and a
cooling air feed to an air feed of the turbine unit. In this way
the air used for cooling the generator in the open air circuit can
be used directly as combustion air for the turbine unit.
[0015] It is also proposed that the turbine unit has an air
preheater which in a cooler stage is connected thermally to the
cooling device and in a warmer stage to a further heat source of
the power plant, for example to a flue gas heat exchanger. In steam
power plants the combustion air is typically heated up by an air
preheater before entry into the flame chamber of the steam
generator. The air preheater is usually supplied with heat from
flue gas. However the flue gas may only be cooled down to above dew
point since otherwise condensation of water with sulfur compounds
results. This would result in greater corrosion. Since the heat
from generator and flue gas is present at different temperature
levels it can expediently be used sequentially for preheating the
combustion air. First of all the combustion air can be preheated by
using waste heat of the generator or warm waste air of the
generator and in a second step the combustion air can be heated up
by heat from the flue gas, in a further heat exchanger for
example.
[0016] Advantageously the turbine unit includes a feed water
heater, with the cooling device being thermally connected to the
feed water heater. In this way waste heat of the generator can be
used to preheat the feed water of a steam process or of a gas and
steam process. The hot cooling medium in the generator cooling
circuit typically reaches the temperature of around 80.degree. C.
The preheating is undertaken expediently immediately beyond the
feed water pump, where the steam circuit usually reaches the lowest
temperature level.
[0017] In principle feed water preheating can be achieved in two
ways: In direct incorporation the feed water flows directly through
the heat exchanger on the generator. In indirect incorporation a
further heat exchanger is used on the feed water side and a
separate circuit transfers the heat from the generator to the feed
water. For indirect incorporation the cooling device advantageously
includes a cooling water circuit which is a part of the feed water
circuit of the turbine unit.
[0018] Large power plant systems usually have an extensive complex
of buildings which, in addition to the machine halls and the
control rooms, also includes office buildings for the
administration. In the respective buildings, depending on type and
use and taking into consideration the appropriate health and safety
at work regulations, appropriate air-conditioning systems must be
provided. To this end heating is required in winter while in summer
both in the office buildings and also in the machine halls cooling
of the ambient air is sensible.
[0019] If the cooling device is connected thermally to a building
heating system of the power plant, generator heat occurring in the
cooling circuit can be made available for heating the
buildings.
[0020] In a further variant the generator waste heat can be used
for operating an absorption cooler for buildings air-conditioning.
This enables generator waste heat to also be included in the
cooling. The overall energy balance of the power plant is increased
by relieving the load on the in-house demand network. The load on
the feedback cooling circuit of the generator can be relieved in
order to contribute in this way to an additional reduction of the
power plant's own demands--through the increased net power plant
output.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The invention will be explained in greater detail with
reference to exemplary embodiments which are shown in the
drawings:
[0022] The figures show:
[0023] FIG. 1 a schematic diagram of power plant with a turbine
unit and a generator, the waste heat of which is used for
preheating a fuel,
[0024] FIG. 2 a schematic diagram similar to FIG. 1, with the fuel
being routed through the generator as a cooling medium,
[0025] FIG. 3 a schematic diagram of a power plant in which
generator waste heat is transferred into an air compressor
inflow,
[0026] FIG. 4 a schematic diagram of a power plant in which the
feed water of a steam turbine is routed through a generator for
heating,
[0027] FIG. 5 a feed water circuit for a steam turbine which is
thermally connected via a heat exchanger to a coolant circuit of
the generator,
[0028] FIG. 6 the feed water circuit in which feed water is routed
as a cooling medium via an intermediate cooling circuit of the
generator,
[0029] FIG. 7 a schematic diagram of the generator, the waste heat
of which is supplied to an air supply before an air preheater for a
steam generator, and
[0030] FIG. 8 a diagram similar to FIG. 7, with an airflow being
supplied to an air preheater as a coolant flow through the
generator.
DETAILED DESCRIPTION OF INVENTION
[0031] FIG. 1 shows a schematic diagram of a layout of a power
plant 2 with a turbine unit 4 which is connected via a shaft 6 to a
generator 24 of a generator unit 8. The turbine unit 4 comprises a
turbine 10 which is embodied as a gas turbine and operates an air
compressor 12 via the shaft 6 in an air supply 14 to a combustion
chamber 16 of the turbine unit 4. In the combustion chamber 16 fuel
from a fuel line 18 is mixed into the compressed air and burned.
The hot exhaust gases are supplied to the turbine 10 for its
operation. In addition the turbine unit 4 comprises a fuel
preheater 20 in the fuel line 18 for preheating the gaseous
fuel.
[0032] During the operation of the power plant 2 the turbine 10
drives the air compressor 12 via the shaft 6 and drives the
generator 24 via a coupling 22. During this operation the generator
24 generates heat which is removed from the generator 24 via a
cooling circuit 26. The cooling circuit 26 and a heat exchanger 28
are a component of a cooling device 30 of the generator unit 8 for
cooling the generator 24. The cooling medium of the cooling circuit
26, for example water, transfers heat in the heat exchanger 28
which it has taken from the generator 24 to a heating circuit 32
through which the heat in its turn is transferred in the fuel
preheater 22 the fuel in the fuel line 18. Through this generator
waste heat is used for the purposes of fuel preheating. This causes
the necessary quantity of fuel for reaching the upper process
temperature in the turbine unit 4 to be reduced and the
thermodynamic efficiency of the power plant 2 is increased.
[0033] Instead of the transmission of the waste heat from the
generator 24 to the fuel in the fuel line 18 by the fuel preheater
20, the waste heat from the generator 24 can be used as depicted in
the exemplary embodiment shown in FIG. 1 for heating of buildings.
A heat exchanger which transfers the waste heat in the heat circuit
to a buildings heating circuit would be used for this purpose
instead of the fuel preheater 20. Also conceivable would be the
routing of the heating circuit 32 directly through a building and
through corresponding heating elements for heating the building for
example.
[0034] FIG. 2 shows a schematic diagram of the power plant 2 with
an alternate cooling device 36. The descriptions below are
essentially restricted to the differences from the respective
preceding exemplary embodiments, to which the reader is referred
for features and functions which remain the same. Components which
essentially remain the same are basically labeled with the same
reference characters and features not mentioned are transferred
into the following exemplary embodiments without being described
once again.
[0035] By contrast with FIG. 1, the fuel line 18 is designed with a
branch which is routed through the generator 24. The quantity of
fuel to be routed through the generator 24 or a fuel preheater 40
can be adjusted by a valve 38 through a control means 34. By
contrast with the preceding exemplary embodiment the fuel preheater
40 is not thermally supplied with waste heat from the generator 24
but from another heat source. Through the combination of heat
transfer to the fuel by the fuel preheater 40 and the cooling
device 36 the fuel in the fuel line 18 can also be heated up to a
desired temperature independently of the heat occurring in the
generator 24.
[0036] Of course an additional arrangement of the fuel preheater 40
in the fuel line 18 from FIG. 1 is also possible and advantageous.
For example it can be arranged in the fuel flow after the fuel
preheater 20 as an additional heat source for heating the fuel.
[0037] In the exemplary embodiment shown in FIG. 3 waste heat is
transferred from the generator 24 via the cooling circuit 26 and
the heat exchanger 28 of the cooling device 30 via a heat exchanger
42 to combustion air in the air feed 14. Since the overall
efficiency of the combined gas and steam power plant can be
increased with a fixed output especially in the part load range if
the compressor inlet temperature of the combustion air is
increased, the combustion air preheating is sensible for increasing
the efficiency of the power plant 2. If the generator waste heat is
used to this purpose in this power range in particular, a
corresponding increase in the thermodynamic efficiency is
achieved.
[0038] A further advantage of the heating of compressor induction
air lies in being able to counteract a danger or air filter,
compressor diffuser and the first stages of the compressor icing
up. Compressor induction air is expediently heated up by this so
called anti-icing if it has a temperature around freezing point,
i.e. typically between +5.degree. C. and -5.degree. C., and when an
air humidity of over 80% exists. The corresponding heating of the
compressor induction air is controlled by the control means 34 and
by means not shown in the diagram for taking heat from the cooling
device 30.
[0039] The schematic diagram in FIG. 4 shows a power plant 44 with
a turbine unit 46 comprising a steam turbine 48. The steam turbine
46 is supplied with fresh steam which drives the steam turbine 48
via a feed water circuit 50. Expanded steam is condensed in a
condenser 52 and routed by a feed water pump 54 to the generator
unit 8 in order to take heat from the cooling device 30 of the
generator unit 8 with it for preheating the feed water. In a vessel
56 the feed water preheated with the generator waste heat is
brought up to its upper temperature and pressure level and is
subsequently routed as fresh steam to the steam turbine 48.
[0040] To make additional cooling of the generator unit 8 possible
the cooling device 30 includes a secondary cooling circuit 58 with
a secondary cooler 60 and a cooling water pump 62. With the aid of
the control means 34 and valve 64 additional heat can be extracted
by the secondary cooling circuit 58 from the generator 24, even if
no feed water heating is necessary at that moment and the feed
water circuit is stationary because the valves 66 are closed.
[0041] The generator 24 is manufactured with a water-called stator
and cooling channels made of stainless steel, typically V2A, so
that the feed water is routed directly through the stator and can
be used for cooling the stator windings.
[0042] Compared to pure steam power processes the quantity of steam
which is normally used for preheating the feed water and is thus no
longer available for energy generation can be reduced.
[0043] In the exemplary embodiments shown in FIGS. 5 and 6 feed
water of the feed water circuit 50 is likewise heated with
generator waste heat. In the layout shown in FIG. 5 the feed water
is heated up directly in a heat exchanger 72 on the generator 24.
By contrast, in the exemplary embodiment shown in FIG. 6, an
indirect incorporation is realized, in which a further heat
exchanger 74 is used on the feed water side and the waste heat from
the generator 24 is transferred to the feed water on a separate
circuit 76.
[0044] FIGS. 7 and 8 show sections from a power plant layout
similar to FIGS. 1 and 2, in which the generator waste heat is used
by means of a heating circuit 32 (FIG. 7) or directly for heating
fresh air for fossil firing of the power plant 2 (FIG. 8). To this
end a heat exchanger 42 is arranged in the air feed 14 to a steam
generator or vessel of the power plant 2 for example for heating
the ambient air with generator waste heat. For additional heating
of the combustion air a further heat exchanger 68 is available
which is supplied with flue gas heat. In the exemplary embodiment
from FIG. 8 the combustion air is routed directly via an air
compressor 70 as the cooling medium through the generator 24 and
thus directly extracts waste heat from the generator 24.
[0045] Since the temperature level of the generator 24 and thus of
the heating circuit 32 is lower than the temperature level of the
flue gas and thus of the heat exchanger 68, the waste heat from the
generator unit 8 is used for first preheating of the combustion
air. The subsequent second preheating to a higher temperature level
occurs in the heat exchanger 68.
* * * * *