MX2011007584A

MX2011007584A - Coupled gas/steam turbine.

Info

Publication number: MX2011007584A
Application number: MX2011007584A
Authority: MX
Inventors: Martin Hadlauer
Original assignee: Martin Hadlauer
Priority date: 2009-01-15
Filing date: 2010-01-08
Publication date: 2012-01-12
Also published as: EP2376758A2; WO2010081656A2; WO2010081656A3; AU2010205940A1

Abstract

A coupled gas and steam turbine system is created, comprising a gas turbine system having a main gas turbine unit and an end expansion stage, a steam turbine system and a coupling heat exchanger, wherein the coupling heat exchanger is arranged between the main gas turbine unit and the expansion stage and is designed such that it provides thermal energy to the steam turbine system.

Description

GAS TURBINE / STEAM COUPLED Field of the invention The present invention relates to a combined gas turbine / steam turbine process with the additional incorporation of thermal energy, especially solar thermal energy, for the generation of technical work or electric current.

BACKGROUND OF THE INVENTION The usual installations with combined gas turbine / steam turbine process work in accordance with the two-stage thermal technique procedure to obtain technical work and, in a wide sense, to obtain electric current. The obtaining of primary current (technical work) is carried out through an open process of gas turbine and the obtaining of secondary current (technical work), through a subsequent process of steam turbine with heat extraction of the current of Exhaust gas from the gas turbine installation. It is disadvantageous that the gas turbine process must operate at a higher temperature (inlet temperature of the gas in the winding of the turbines> 1250 ° C), since otherwise the exhaust gas decreases at a relatively low temperature and since It can not be used efficiently for the steam turbine process. The heating of the entire installation is carried out in a combustion chamber upstream of the turbine stages, using high value fossil fuels without ash formation. The pressure losses in the heat exchanger for the thermal decoupling result in significant drops in the total installation. A partial load decoupling or the elimination of the thermal decoupling for the steam process is almost impossible, since then the efficiency of the total installation becomes correspondingly low.

BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to be able to operate efficiently a gas turbine installation with variable thermal decoupling for a steam turbine process until the steam circuit is eliminated. Here, the thermal decoupling can only serve for the partial heating of the steam turbine process and a combination with at least one other heat source such as an incorporation of solar heat can optionally be provided.

Said objective is achieved by the coupled installation of gas turbine and steam turbine in accordance with the independent claim. Preferred embodiments are described in the dependent claims.

In accordance with an exemplary aspect of the invention, there is provided a coupled gas turbine and steam turbine facility, which has a gas turbine installation with a gas turbine main unit and a final expansion stage, an installation of steam turbine and a coupling heat exchanger. This heat exchanger is placed between the main gas turbine unit and the final expansion stage and is designed in such a way that it provides thermal energy to the steam turbine installation.

In particular, the coupled gas turbine and steam turbine installation can have a heat exchanger through which primary gas flows from the gas turbine or gas turbine circuit. In particular, the gas turbine main unit can be the turbine unit arranged in the high pressure part of the gas turbine installation, that is, it can decompress at an intermediate pressure the gas, air or smoke gas that is it is under high pressure, through one or several stages of expansion, while the final expansion stage decompresses the flue gas from the intermediate pressure at a low pressure, for example, atmospheric pressure or external pressure. That is, the final expansion stage may be disposed in the low pressure part of the gas turbine installation. Especially, the coupling heat exchanger can connect the gas turbine installation and the steam turbine installation, for example, can be used to heat the steam turbine installation. In other words, the heat exchanger can be arranged in the exhaust gas stream, either air or flue gas, of the main gas turbine unit and can perform a thermal decoupling of the exhaust gas stream from the unit main gas turbine.

A fundamental advantage of the special gas turbine connection with the thermal decoupling mentioned here for the steam turbine process is that the temperature leaving the main gas turbine arrangement is slightly higher than in the installations with thermal decoupling after leaving the last stage of turbines. This makes it possible to operate a highly efficient steam turbine process. Another advantage results from the fact that pressure drops in the coupling heat exchanger due to the high pressure level in the gas stream produce only imperceptible yield decreases in the gas turbine process and, as a result, exchangers can be used. Compact thermal with a high degree of transfer.

The little heat extraction with less steam overheating or the complete elimination of the steam circuit, does not produce any significant decrease of the gas turbine process, since, on the other hand, the heat feedback becomes greater and with a temperature of entry to the turbines constant, less fuel is used. Thus, the load of the thermal decoupling can be regulated through the fuel supply without decisively changing the current parameters for the gas turbine stages. The thermal decoupling serves mainly for the superheating of the feedback condensate from the circulation of the steam turbine.

According to an exemplary embodiment of the coupled gas turbine and steam turbine installation, the steam turbine installation has an additional heating device. In particular, the additional heating device can be powered by solar energy, although lower value fuels such as biomass can also be used.

In accordance with an exemplary embodiment of the coupled gas turbine and steam turbine installation, the gas turbine installation further has a second heat exchanger arranged between the steam turbine and the condensing unit. In particular, said heat exchanger can be designed to feed heat to a high pressure condensate.

In accordance with an exemplary embodiment of the coupled gas turbine and steam turbine installation, the coupling heat exchanger is also designed to evaporate a condensate. In particular, this heat exchanger can be designed to evaporate its condensate from the steam turbine installation.

In accordance with an exemplary embodiment of the coupled gas turbine and steam turbine installation, the heat exchanger is connected downstream of the coupling heat exchanger and is designed in such a way that it feeds back heat to a high pressure area of the heating system. gas turbine. In particular, the heat exchanger is responsible for a heat feedback and / or preheating and / or heating the gas that is fed to the high pressure zone of the gas turbine main unit and / or the highly compressed air after leave the compressor unit. Given the decisive use of the heat exchanger for the heating of highly compressed air, it can also be referred to as an air heater. For example, the air heater may be connected upstream of the final expansion stage.

According to an exemplary embodiment of the coupled gas turbine and steam turbine installation, the gas turbine installation further has a branch between the coupling heat exchanger and the air heater, which is made in such a way that a part of the gas stream leaving the heat exchanger, evades the thermal heater. In particular, the branch can be made in such a way that part of the gas stream evades the air heater and is fed directly to the expansion stage, while another part of the gas stream is fed to the air heater .

In accordance with an exemplary embodiment of the coupled gas turbine and steam turbine installation, it is designed in such a way that the steam turbine installation becomes inactive when an incorporation of heat through the additional heating device falls below a predefined threshold value. In particular, the inactivation of the steam turbine installation can be achieved by stopping power feeding through the coupling heat exchanger. In other words, the steam turbine circulation process can be eliminated or inactivated.

According to an exemplary embodiment of the coupled gas turbine and steam turbine installation, the gas turbine installation further has a heating device upstream and / or downstream of the turbine main unit. In particular, the heating device can have two partial heating devices, one of which is connected upstream of the turbine main unit and the second one downstream thereof.

A gas turbine process possible in accordance with an exemplary aspect of the invention for thermal decoupling in a coupled gas turbine and steam turbine installation is briefly described below. The gas turbine installation has a main gas turbine arrangement with one or several stages of final expansion in the high pressure part and a final expansion stage in the low pressure part, as well as a device for heat feedback or, the preheating or heating of the highly compressed air of the compressor unit. The device for burning fossil or biogenic fuels is upstream or downstream of the expansion stages in the high pressure part of the installation. In the case of the combustion chamber downstream, heated air flows exclusively through the expansion stages of the high pressure part. The heating of the air is carried out by means of a thermal exchanger, the air heater, through which high temperature gas flows on the primary side. By means of the device for combustion downstream of the expansion stages in the high pressure part, it is achieved that the warped with high temperature circulation stay away from the harmful influences of smoke gases with ash content of lower fuel value. Both in the case of the combustion chamber upstream and downstream, smoke gas flows through the expansion stages in the low pressure part.

It has been observed that this gas turbine process works very well for variable thermal decoupling. In the foregoing, said thermal decoupling is performed from the gas stream after leaving the main gas turbine unit at a medium pressure level. Under special conditions, this thermal decoupling is not only very interesting for the heating of thermal networks, but also for processes for the additional obtaining of technical work and electric current, in particular for the heating of steam turbine processes. The condition for an efficient combined process would be in particular that the heat of the high temperature of the gas turbine process is used to a large extent for the superheating of the steam. Therefore, in order to operate the total process efficiently, another source of heat must be included in the steam circulation, which is responsible for the low temperature zone of the condensate preheating and evaporation. It is particularly profitable to operate the total installation when the additional heat comes from lower-value fuels, heat from thermal processes upstream or solar energy.

An important objective of an exemplary aspect of the present invention is to be able to efficiently operate a gas turbine installation with thermal decoupling for a steam turbine process which in the low temperature range is heated primarily by solar thermal energy.

For this, heat is decoupled from a special gas turbine arrangement with a main gas turbine arrangement with one or more expansion stages in the high pressure part as well as an expansion stage in the low pressure part, and a device for heat feedback, wherein the thermal decoupling from the gas stream is made after leaving the main gas turbine unit and used for heating the steam turbine process, which is additionally heated through another heating device for the low temperature range.

An essential advantage of this special gas turbine connection with the thermal decoupling mentioned here for the steam turbine process is that the temperature after leaving the main gas turbine arrangement is a little higher than in the known installations with thermal decoupling after leaving the last stage of turbines. This allows to operate a highly efficient steam turbine process. Another advantage is that the pressure drops in the heat exchanger due to the high pressure level in the gas stream, only produce imperceptible yield decreases in the gas turbine process and, therefore, can be used compact heat exchangers with a high degree of transfer. It is particularly advantageous in combination with the incorporation of solar heat that the gas turbine installation can operate efficiently even in the event of removal of the thermal decoupling or in the case of reduced heat extraction.

A reduced heat extraction with a lower steam overheating or the complete elimination of steam circulation does not produce any significant decrease in the efficiency of the gas turbine process, since the heat feedback, on the contrary, becomes greater and With a constant intake temperature to the turbines, less fuel is used. In this way, the load of the thermal decoupling can be regulated by means of the heat supply, without decisively modifying the current parameters for the gas turbine stages. The thermal decoupling serves mainly for the superheating of the feedback condensate from the circulation of the steam turbine. In order not to subject it to too large load variations of the solar circuit, there is also the possibility of evaporating the condensate through the thermal decoupling of the gas turbine circulation. However, this must be done only to a limited extent if expensive fuels are used for the heating of the gas turbine installation, since the exergy of the heat incorporated in the temperature range of the evaporation of the condensate (~ 200 ° C) ) is low by nature. Ideally, the steam turbine can be regulated in a band of moderate performance.

With the strategy of limiting the temperature in the solar circuit at low temperatures and using combined fossil and / or biogenic energy carriers, an efficient heat incorporation is achieved through the solar collectors. Thus, the evaporation can take place directly in the collectors or is carried out by intermediate storage means. Obviously, with the corresponding back pressure, the heat of condensation of the circulation of the steam turbine can also be transmitted to heating networks or used as process heat, for example, for seawater desalination installations. By "low temperature" in the solar circuit is meant above all evaporation temperature in the steam turbine process. In order not to reach too high pressures in the solar collectors and to achieve a high incorporation of heat, moderate evaporation temperatures are considered around 200 ° C.

Brief description of the figures Other characteristics and features of the present invention result from the following description of the figures. They show: Figure 1, a schematic reproduction of a gas turbine installation with thermal decoupling for a steam turbine process according to the prior art.

Figure 2, a schematic reproduction of a gas turbine process that is used here, with an upstream combustion chamber, a downstream combustion chamber and the coupling of the steam turbine process through the coupling heat exchanger, in accordance with one embodiment of the invention.

Figure 3, a schematic reproduction of a gas turbine process that is used here, with a downstream combustion chamber, a special thermal decoupling through the coupling heat exchanger and an additional device for branching the gas stream .

Detailed description of the figures Next, the figures of exemplary embodiments of the invention are described, in which the same or similar elements in different figures have the same references or similar references.

Figure 1 shows a schematic reproduction of a gas turbine installation with thermal decoupling for a steam turbine process according to the prior art. In it air is compressed by a compressor unit 1 and in a combustion chamber 4 it becomes smoke gas with high temperature which is then decompressed to the external pressure through expansion stages 5, 6 of the gas turbine arrangement . In the exhaust gas stream of the gas turbine, on the primary side there is a heat exchanger 7 for heating the process of the steam turbine. This is a closed circuit which is heated in the secondary circulation of the heat exchanger 7. The process of the steam turbine takes place in a steam turbine installation having a steam turbine unit 8 with a condensing unit 9 downstream. . The steam turbine process also has a pump 10 which delivers the condensate to a condensate collection unit 12. The condensate in the condensate collection unit 12 is then at least partially evaporated and fed to the heat exchanger 7. In the basic load (without solar heating), the entire evaporation and overheating is carried out by thermal decoupling from the gas turbine circuit. By incorporating solar heating energy 13 to the evaporation of the condensate, the power of the steam turbine 8 must be increased above the increasing flow rate, since the thermal decoupling from the exhaust gas must remain as high as possible. An elimination of the steam turbine process is not convenient, since the heat of the exhaust gas still contains a high exergy. In this way, the solar percentage of the energy depends to a large extent on the regulation behavior of the steam turbine and is very limited. The performance of the steam turbine in proportion to the extraction of heat from the exhaust gas is relatively low, since even with the solar support in the evaporation, a large part of it takes place through thermal decoupling 7.

Figure 2 shows a schematic reproduction of a gas turbine process according to a first coupled gas turbine and steam turbine installation mode. The gas turbine installation has a compressor unit 1 by means of which air or gas is compressed, which is then fed to a heat exchanger 2, where the gas is subjected to a first heating. The preheated gas is then brought into a combustion chamber 4 upstream and transformed into flue gas before being taken to a gas turbine main unit 5 and subjected to a first expansion. The expanded flue gas at an intermediate pressure is then fed to a second heat exchanger 7, which extracts heat from the expanded smoke gas. The cooled flue gas is fed to a combustion chamber 3 downstream, in which additional combustion takes place with heating. The newly heated flue gas is then brought to the heat exchanger 2 and used for the aforementioned preheating of the air (gas) flowing after leaving the compressor unit. Then, the flue gas is fed to a second expansion stage 6 with decompression under reduced pressure, or else at external pressure.

The steam turbine installation in which the steam turbine process takes place, is similar to that described above in relation to Figure 1. The incorporation of heat for the steam superheat for the closed steam turbine process is carried out in a primary way through the heat exchanger 7. The superheated steam is taken from the heat exchanger 7 to a steam turbine unit 8 with a condensing unit 9 downstream. The condensate thereof is then brought to high pressure through a pump 10 and passed through a condensate collection unit 12. The collected condensate is fed to an additional heating device 13, which operates, for example, in a solar manner, although said additional heating device can also be heated with numerous energy carriers, even lower value and / or ecological fuels, for example, biomass. The evaporated condensate is then fed back to the condensate collection unit 12 from which it is taken to the heat exchanger 7 for overheating.

Thanks to the heat exchanger 2 for heat recovery, this installation achieves a very high degree of technical effectiveness even in the case of measured temperatures entering the turbines without the inclusion of the steam turbine circuit. According to the invention, the thermal decoupling for the steam turbine process is carried out through the heat exchanger 7, which is directly downstream of the primary side of the expansion stages 5 in the high pressure part. The fundamental advantage compared to the system shown in Figure 1 is that, in combination with the gas turbine process shown here, high solar heating incorporations are achieved, since all the evaporation heat can be introduced through the collectors solar Ideally, the steam turbine can be regulated in a moderate power range. In order to maintain as high as possible the degree of technical effectiveness of the heating heat incorporated through the heat exchanger 7, in the case of a reduced solar heating power, the decoupling of heating heat through the circuit must also be reduced of the gas turbine. Depending on the possibility of regulation of the steam turbine, the measurement of the decrease in power will be in a moderate range. If the incorporation of solar heat is eliminated, the steam turbine circuit can be eliminated, without decisively decreasing the efficiency of the gas turbine installation, since the fuel supply decreases correspondingly.

Figure 3 shows the schematic reproduction of a gas turbine process in accordance with a second coupled turbine gas turbine and steam turbine installation mode. The gas turbine installation has a compressor unit 1 with which air (gas) is compressed, which is then fed to a heat exchanger 2 for heating at the inlet temperature to the turbine. The heated air (gas) is then brought to a gas turbine main unit 5 and subjected to a first expansion. The air (gas) expanded at an intermediate pressure is then brought to a second heat exchanger 7 which extracts heat from the expanded air (gas). The cooled air (gas) is then fed to a branch 14 carrying a first part of the air (gas) cooled and partially expanded to a combustion chamber 3 downstream, in which high temperature smoke gas is generated before carrying it through the heat exchanger 2 to a second expansion stage 6 in which the smoke gas is decompressed at a low pressure, or at the external pressure. After the branch 14, a second part of the cooled and partially decompressed air (gas) is mixed with the flue gas stream after leaving the heat exchanger 2.

The steam turbine installation in which the steam turbine process takes place is similar to that described above in relation to Figure 2. The incorporation of heat for the closed steam turbine process takes place primarily through of the heat exchanger 7. The superheated steam is taken from the heat exchanger 7 to a steam turbine unit 8 with an additional downstream heat exchanger 11, in which a part of the energy is extracted from the decompressed steam. Downstream of the additional heat exchanger 11, there is a condensing unit 9. The condensate of the condensing unit 9 is then carried by a pump 10 to a condensate collection unit 12 in which the condensate is collected and brought to the an additional heating device 13, which operates, for example, in solar mode, although said additional heating device can be heated with numerous energy carriers, even lower value fuels such as biomass. The evaporated condensate is then fed to a condensate collection unit 12 from where it is then brought to the heat exchanger 7 for overheating. Additionally, a portion of the condensate from the condensate collection unit is brought to the additional heat exchanger 11 to evaporate there before being carried through the condensate collection unit 12 to the heat exchanger 7. In contrast to the mode described in FIG. Figure 2 also shows the possibility of feeding a part of the condensate in liquid form to the heat exchanger 7.

Through the branch 14, a reduced part (for example, 10 to 20%) is brought into the flue gas stream after leaving the heat exchanger 2 for heating the air. The above is particularly advantageous in the case of complete thermal decoupling, since the air in the heat exchanger 7 must be brought to the corresponding low temperatures. The main objective of this work is to place the pole of the heat exchanger 2 on the side of the secondary circuit and, in this way, achieve the best possible heat recovery. In the combustion chamber 3 downstream as shown here, it must be remembered that the inlet temperature of the flue gas in the heat exchanger 2, with a predetermined temperature of the air entering the turbine, is correspondingly higher. Thanks to the combustion device 3 downstream, lower-value fuels and biomass with ash formation can be burned, without the warping of the turbines being damaged. The thermal intercarabator 7 for the superheating of the steam is located on the primary side in the stream of pure air. Thanks to the evaporation of additional condensate in the heat exchanger 7, the minimum heat load of solar heating can be reduced with a predetermined minimum load of the steam turbine. In the case of back pressure installations, by using the highest possible superheat temperature, the steam in the turbine stage does not expand to the wet steam range. In order to maintain the steam turbine process as efficiently as possible, it is advisable to intercalate a heat exchanger 11 for heat recovery.

The invention is not limited only to the variants presented here, but also to the obvious combinations that can be derived from them. In the characteristics according to the invention shown schematically in all the figures, it should be noted that the different components as well as the feed lines can be manufactured in all the different production variants and materials. All the compression and expansion processes related to the technical work must also be able to perform with other work machines and not only with the turbine sets considered here and with a continuous current.

Claims

1. A coupled gas turbine and steam turbine facility, which has a gas turbine installation with a gas turbine main unit (5) of a final expansion stage (6) and an upstream heat exchanger (2) of the final expansion stage (6) and through which flows from the primary gas side of the gas turbine installation; a steam turbine installation and a coupling heat exchanger (7), this being arranged between the gas turbine main unit (5) and the final expansion stage (6) and is designed in such a way as to provide energy thermal to the steam turbine installation.

2. The coupled gas turbine and steam turbine installation as claimed in clause 1, characterized in that the steam turbine installation has an additional heating device (13).

3. The coupled gas turbine and steam turbine installation as claimed in clause 2, characterized in that the additional heating device (13) is powered by solar energy.

4. The coupled gas turbine and steam turbine installation as claimed in clause 3, characterized in that the additional heating device (13) is designed to evaporate condensate.

5. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 4, characterized in that the coupling heat exchanger (7) is designed in such a way that it superheats the steam of the turbine installation steam.

6. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 5, characterized in that the steam turbine installation also has a steam turbine (8) and a second heat exchanger (11) downstream of the steam turbine (8).

7. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 6, characterized in that the coupling heat exchanger (7) is also designed to evaporate a condensate.

8. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 7, characterized in that the heat exchanger (2) is downstream of the coupling heat exchanger (7) and is designed to feed heat to a high pressure area of the gas turbine installation.

9. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 8, characterized in that the gas turbine installation also has a branch (14) disposed between the coupling heat exchanger (7) and the heat exchanger (2) and which is designed in such a way that a part of the gas stream leaving the coupling heat exchanger (7) evades the heat exchanger.

10. The coupled gas turbine and steam turbine installation as claimed in any of clauses 2 to 9, characterized in that it is designed in such a way that the steam turbine installation becomes inactive when the incorporation of The heat of the additional heating device (13) falls below a predetermined threshold value.

11. The coupled gas turbine and steam turbine installation as claimed in any of Clauses 1 to 10, characterized in that the gas turbine installation has a heating device (3, 4) upstream and / or downstream of the main turbine unit (5).