EP1050667A1 - Combined power plant with auxiliary burner - Google Patents

Abstract

The combination installation comprises at least one gas turbine (1), at least one steam turbine (4) and at least one waste h steam producer (6) containing at least one evaporator (604) and a fresh steam overheater (606). The waste heat steam producer ha flowing through it a tension-relaxed work medium (52,53) of the gas turbine and a work medium (71-75) of the steam turbine in counterflow. In the waste heat steam producer is arranged additional heating (605) in the flow direction of the tension-relaxed work med of the gas turbine downstream of the fresh steam overheater of the waste heat steam producer.

Description

Technical field

The present invention relates to a combination system consisting of at least one gas turbine, at least one steam turbine, and at least a heat recovery steam generator. It will continue to operate of such a system.

State of the art

In terms of efficient energy conversion in power plants, these are often designed as a combination system. This is done in a waste heat boiler Exhaust gas from a gas turbine, which immediately after exiting the Turbine still has a very high temperature, used for high tension to generate superheated steam for the operation of a steam turbine. With help sophisticated circuits of the water-steam cycle Exhaust heat of the gas turbine to a large extent in the downstream Steam turbine process used. Such optimized systems, work for example with multiple overheating of the steam at different Press in the boiler. You are thus able to heat up almost to take advantage of any temperature level above the ambient temperature. in the In return, systems optimized in this way are very complex, and therefore also expensive.

In return, the plants - which are optimized with high capital investment - are often not fully used. Liberalized electricity markets don't just demand one efficient energy implementation, but also high flexibility in the Power generation. Although the margins in the generation of base load due to competition are low, can be used to cover Peak loads can often be achieved at a much higher price. A large proportion of the generated profit can be generated with a few percent of the electrical energy, or in a fraction of the life of one Power plant, be generated.

Therefore, it is for the private sector engaged in liberalized electricity markets organized utilities almost imperatively to have reserve capacities. In A limited amount can cover peak power reserves be mobilized from hydropower plants. Techniques like Air storage turbines still have to be used today and according to all technical discretion an exotic status can be awarded at least in the medium term. The establishment of peak load gas turbine power plants is economically the bottom line mostly less attractive.

For this reason, for example, base load systems only use 90 or 95% of their operated at maximum power and thus reserves power it is often plants that, as described at the beginning, with high Capital expenditure is trimmed to the best levels of efficiency. With one Operating mode, there are two counterproductive effects: On the one hand, a high investment in capital and resources over long periods of time fully used. On the other hand, a system operated in this way does not run on yours Design operating point, and thus with an efficiency that is less than the actually achievable - and expensive bought! - is.

Another option is the gas turbine of a combination plant to operate temporarily with increased performance. However, has a short-term Increasing the hot gas temperatures, for example, a sustainable one negative effect on the life of the machine components. Also the Increase in performance by introducing water or steam into the Combustion chamber or the hot gas path of the gas turbine is not unproblematic. In addition, these measures will soon reach theirs quantitative limits.

It has long been known that additional firing in waste heat boilers to implement. The gas turbine exhaust, which is still a lot Contains oxygen, added fuel and burned it. This method has so far been used in particular to supply fresh steam via the To overheat the temperature of the gas turbine exhaust gas. In the Electricity generation is a big disadvantage of this technology that the additional amount of fuel introduced only with steam turbine efficiency is implemented instead of with the significantly higher combination efficiency. Out The additional firing is still interesting for operational reasons, for example, if process steam is generated in the waste heat steam generator and steam generation from the power generation of the gas turbine to be decoupled.

Additional firing can also be of interest to the delivery to increase electrical power in times of peak demand. If high Prices for top performance that can be provided quickly are increased electricity generation costs due to the lower efficiency acceptable, especially when providing peak performance with low capital investment.

However, the additional firing reaches its limits when the exhaust gas from the Gas turbine is already at a temperature level that is little below the permissible maximum temperature of the boiler. Such a case is given, for example, when gas turbines of the type ABB GT24 / GT26 can be used in the combination process. Here is the Exhaust gas temperature already well above 600 ° C. A bigger one Increasing the temperature through additional firing requires a redesign of the Boilers using expensive and complex to process High temperature materials.

In summary, it can be said that it is advantageous to have one To build a combination system so that an acceptable ratio of equipment Effort and efficiency result. Here offers a facility consisting of Gas turbines with reheating of the partially relaxed medium as described in EP 0 620 362 B1 or US 5,577378 are described, and one Steam turbine plant, good conditions. When using a steam turbine without reheating, the efficiency is reduced, on the other hand the impression boiler to be used then requires much less Investment costs. It is also an advantage to have large power reserves to keep the nominal full load operation ready. Such a facility could in Base load operation at nominal full load, operated at its best efficiency be, which is the nominal compared to an exhausted combination system reduced efficiency is at least partially compensated.

It would make sense to realize the peak load operation by using a Additional firing a performance increase of the steam turbine is realized. How set out above, the poorer efficiency, with which the additional fuel is used. For the Electricity generated as a peak load can achieve a very high price on the market be such that a higher specific fuel consumption is economical is acceptable. A conventional additional firing for the state of the art however, brings the peak load operation for the reasons described above state-of-the-art gas turbines hardly a big increase in performance, and it is for gas turbines with rather moderate exhaust gas temperatures, through the maximum permitted temperature in the heat recovery steam generator is limited.

Presentation of the invention

This is where the invention comes into play. In a combination system of the type described at the beginning Art is a way to create an additional firing in the boiler to be able to activate the largest possible additional service. There is one avoid elaborate redesign of the boiler under all circumstances.

This is achieved according to the invention by the additional firing in Flow direction of the relaxed working medium of the gas turbine downstream the live steam superheater of the heat recovery steam generator is arranged.

The core of the invention is therefore, in a combination system, the exhaust gas from the gas turbine first cool in the superheater from the originally high temperature, by a larger distance up to the maximum when using the additional firing permissible temperature of a waste heat boiler, and thus the Water-steam circuit to supply additional heat to the steam turbine to increase the power output of the steam turbine.

According to the invention, the additional firing is therefore not at the inlet of the exhaust gas arranged in the boiler, but downstream of at least one superheater. On this point is the exhaust gas of the gas turbine when the The boiler has already cooled down considerably, up to the boiling point of the Feed water. The temperature difference by which the exhaust gas in the superheater cooled, can now be fired without the To have to design waste heat boilers for higher temperatures.

Another advantage of the invention is - in addition to the larger to be fired Performance - that the additional firing acts on the evaporator pipe instead on a superheater. This will prevent the superheater surfaces with the radiant heat of the additional firing and at the same time the high Hot gas temperatures applied.

The heat recovery steam generator of a combination system according to the invention can be used as conventional drum kettle or as a single-pipe kettle. Also if in the latter type there is no sharp dividing line between the superheater part and the evaporator of the heat recovery steam generator is more, that It should be clear to the specialist where the additional firing according to the Claims to be arranged, just in the flow direction of the relaxed Working medium of the gas turbine downstream of the live steam superheater on the one hand, that the gas turbine exhaust gas has already cooled down, on the other hand, so that the additional firing on heat exchanger surfaces acts from which the heat - especially the radiant heat of Additional firing - discharged by a liquid in all operating states becomes.

In summary, it can be said that a great advantage of the Execution of a combination system according to the invention with additional firing in addition Avoiding any extreme temperature peaks is that none Radiant heat is applied to superheater surfaces, which is ultimately a problem simple and inexpensive design of the superheater, for example as Finned tube heat exchanger, enables.

A preferred operating mode for such a combination system is the following: In The gas turbine operates at full load in nominal full load operation. The exhaust of the Gas turbine flows through one after the other in the heat recovery steam generator Superheater, an evaporator and an economizer. The amount of steam results in this operating state so that the temperature of the exhaust gas on Leaves from the evaporator just above the boiling point of the Feed water lies. In the event that a peak load is requested, is now the auxiliary firing is switched on, which increases steam production. The thermal output of the additional firing can be increased up to the maximum Temperature of the gas turbine exhaust gas at the outlet from the superheater only is still slightly above the boiling point of the feed water, or the maximum permissible temperature of the additional firing for the boiler is reached.

It is important for the process to be carried out efficiently that the Heat exchange surfaces in the boiler for the increased water / steam mass flow are sufficiently large. However, none will higher requirements for the high temperature usability of the Boiler components provided as in a combination system without additional firing.

The execution of the combination system according to the invention without Reheating is a preferred variant in cases where a The greatest possible potential for providing peak load at low Investment costs should be used. The conventional arrangement of a Reheater at the same position in the heat recovery steam generator as that Live steam reheater is only useful if this is the case caloric potential of the gas turbine exhaust gas is sufficiently high to between the entry temperature of the hot gas into the boiler and the Boiling temperature of the feed water to provide enough energy to also a greatly increased amount of steam due to the additional firing on the Fresh steam temperature to overheat and this amount of steam at the same time reheat. On the other hand, it can prove expedient - in Dependence on the enthalpy flows in the heat recovery steam generator - one Reheater in the direction of the hot gas flow downstream of the To arrange additional firing. With such an arrangement Additional firing also on the reheater, which is why in the Additional firing can be fired a greater performance. It is still advantageous, the piping of the reheater on the same Position in the boiler like the pipes of the evaporator, and thereby Evaporator tubes between the additional firing and the pipes of the To arrange reheater. This way the superheater will go through the wet operated evaporator from the heat radiation of the Additional firing shielded, and can therefore be much simpler Construction can be carried out.

It is also advisable to split the feed water line. In doing so, a Part of the feed water via a first line directly to one Economizer run and at a point within the Heat recovery steam generator is farthest from the gas turbine, that means in relation to the direction of flow of the gas turbine exhaust gas farthest downstream, introduced into the economizer or the evaporator. Another part of the feed water is over one or more Feed water preheater directed, and preheated the first partial flow a further upstream point of the economizer, if necessary, also directly in the boiler drum or Evaporator tube, mixed. Especially when operating with an elevated Feed water / live steam mass flow are these feed water preheaters in Connection with the parallel routing of two feed water partial flows advantageous. The partial flow led through the feed water preheater is in the Dimension and preheated to the first partial flow so that the total mass flow when leaving the economizer is almost on the Boiling temperature is. The circuit variant in which a first partial flow is fed directly into the economizer, compared to the preheating of the Total mass flow is preferred because the temperature of the coldest in the Economizer inflowing water pretends to be the lowest temperature which uses the calorific potential of the gas turbine exhaust gas can.

The feed water preheaters are operated with steam, which is more suitable Place of the steam turbine is removed. This initially disturbing loss Working fluid of the steam turbine can be increased when operating Steam mass flow can even be an advantage. Because just in operation partially expanded steam with increased fluid mass flow and whose enthalpy is fed to the cycle at another point, the relieved last stages of the steam turbine. The flash floods can therefore built smaller and better for normal operation, i.e. combination operation without Additional firing and with a lower amount of steam. Depending on System design can possibly be due to expensive additional floods in the Low pressure part of the steam turbine can be dispensed with.

Each branch of the feed water line is expediently equipped with a shut-off and regulating device. When operating the combi system with oil as fuel the shut-off device in the branch that leads directly to the economizer, are closed, and another feed water partial stream is expediently heated to above the dew point temperature of sulfuric acid, to avoid corrosion damage to the boiler tubing.

In a combination system according to the invention, condensate and Feed water pump summarized, and that for peak load operation required pump output on two identical pumps connected in parallel divided up. In nominal operation, the operation of a single pump is sufficient; the second pump only needs the additional one during peak load operation Promote the amount of feed water. This increases availability, since the system at Pump failure still operated at full load without additional firing can be.

It has already been indicated above that the sharp increase in steam production can lead to problems with the swallowing capacity of the steam turbine. In In this context, it may prove useful to do more Tap points in the water-steam cycle, of which steam is to be provided the stressed working medium of the gas turbine is guided. This steam can on the one hand, are introduced into the combustion chambers, where a higher one Amount of fuel can be supplied, on the other hand, the steam can for cooling thermally highly stressed components of the gas turbine be used.

As already mentioned in the introduction, the arrangement according to the invention is the Additional firing between superheater and evaporator is an advantage if the exhaust gas temperature of the gas turbine is only slightly below the maximum permissible boiler temperature, which is particularly the case is when gas turbines with reheating the partially relaxed working medium be used. Such turbines are from EP 0 620 362 B1 or the US 5,577,378 and US 5,454,220 known which fonts are integral Represent part of the present description.

The investment costs will continue to be reduced if the plant in the single-shaft design is built, in which a gas turbine and a Steam turbine act on a common generator. On the other hand, the Execution of the combination system according to the invention also then operational advantages if several gas turbines each have one Heat recovery steam generator deliver steam for a steam turbine. Here at Failure of a gas turbine the additional firing in the steam generators of the the gas turbines in operation at least partially lost power compensate.

In addition to the advantages for peak load availability discussed above the inventive design of a heat recovery steam generator with Additional firing compared to the prior art also has other advantages for the operation and construction of the boiler and steam turbine. Since the Superheater arranged in the direction of the exhaust gas flow before the additional firing is, as already mentioned, the superheater is not subject to changing influences Heat radiation exposed to the auxiliary firing, and therefore can comparatively inexpensive as a finned tube heat exchanger. In addition, the live steam data of the steam turbine vary significantly to a lesser extent with the operation of the auxiliary firing than if it were on the live steam superheater would work.

Brief description of the drawing

The invention is described below with reference to the drawing Exemplary embodiments explained. Fig. 1 shows a preferred embodiment of a Combination system according to the invention, as characterized in the claims is. Fig. 2 shows a development of the combination system shown in Fig. 1, at the bleed steam from the steam turbine into the combustion chambers of the gas turbine is injected. Fig. 3 shows a further circuit variant with a Steam injection into the gas turbine, in which the steam is extracted from the Water / steam cycle very flexible to the swallowing ability of different Components in the water / steam cycle is designed to be adaptable 4 and 5 finally show two variants with an intermediate overheating of partially relaxed steam.

The direction of flow of all media involved, if relevant to the invention, is indicated by arrows. The exemplary embodiments also raise no claim to be complete, or a combination system in all To present details. On the other hand, all components and functional groups are shown that are necessary for understanding the invention.

Way of carrying out the invention

1 shows a first example of the embodiment of a Combination system. A gas turbine 1 is connected to a generator 2, and drives this. The generator 2 is still an automatically acting Coupling 3 connected to a steam turbine 4. The gas turbine sucks one Fresh air amount 51, which in the compressor 101 to a working pressure is compressed. The compressed air is in a first combustion chamber 102 a strongly sub-stoichiometric amount of fuel 42 is supplied, and burned. The high-tension working medium is in a first turbine 103 partially relaxed. In a second combustion chamber 104 Working medium through the combustion of a further quantity of fuel 43 reheated, and in a turbine 105 approximately to ambient pressure relaxed. The relaxed working medium 52 is still on a high temperature of, for example, 600 ° C, which is sufficient Amount of steam 74, 75 to be sufficiently overheated; also can be found in the Exhaust gas from the gas turbine still contains a high proportion of oxygen. The relaxed Working medium 52 is passed through a heat recovery steam generator 6, wherein Heat to at least one inflow of feed water 71.72 what amount of feed water is emitted in the heat recovery steam generator is evaporated and overheated. The superheated steam 75 thus generated is in the Steam turbine 4 relaxed. Relaxed steam 76 is in the condenser 7 liquefied and up again by the condensate and feed pumps 8 and 9 brought the live steam pressure. The feed water 77 is expediently led a first feed water preheater 10, where it by means of one of the Steam turbine removed steam amount 78, for example, to 60 ° C. is preheated. The temperature in the feed water preheater is regulated by the control member 21 controlling the bleed steam amount 78. Through this Preheating is used, for example, when operating the combined system with natural gas Fuel the precipitation of moisture in the boiler tubing in one first part of the Economizer 601 prevents long-term Corrosion damage can be avoided.

In the combination system shown as an example, the design of the Gas turbine as a gas turbine with sequential combustion is not essential to the invention, still the single-shaft arrangement, with steam turbine and Gas turbine working on a common generator. These characteristics However, they correspond to the latest technology and are related to the To implement invention with advantage. So the illustrated ensures Gas turbine design is inherently high efficiency, and is due to the high exhaust gas temperatures particularly good for use in a Combination system suitable. The single-shaft design enables a combination system create confined space; in connection with that only one generator and only a generator foundation is necessary, the system performance is included low investment costs provided. The invention can, however, without further can also be realized when the steam turbine and the Gas turbine each act on a generator. Likewise, that of steam generated in several gas turbines via heat recovery steam generator Steam turbine act.

In a first operating case, a quantity of feed water 71 flows out of the Feed water preheater 10 into a first part 601 and from this into one second part 602 of the economizer. At the exit from the second part of the Economizer 602 ideally water 73 is at boiling temperature or only little below, and is fed into the drum 603. Boiling water flows from drum 603 into evaporator 604, absorbs further heat there, and flows back into the drum 603. There the water becomes that Part to which the absorbed heat is insufficient for evaporation; deposited; the separated liquid is again through the Evaporator 604 passed. Saturated steam 74 flows out of the drum 603 into the Live steam superheater 606, and finally flows as superheated Live steam 75, ideally almost at the temperature of the relaxed Working medium 52 of the gas turbine, in the steam turbine 4. The relaxed Working medium of the gas turbine flows through the components mentioned Heat recovery steam generator in reverse order, and cools continuously from.

It is also advantageous for the function of the combination system, if that from the Economizer outflowing water a temperature close to the boiling point having. To ensure this, the economizer is equipped with a second one Inflow connection provided over the between the first and the second Part of the economizer another preheated amount of feed water 72 in the economizer is introduced. In comparison, this is a stronger one Preheating the feed water quantity 71 in the feed water preheater 10 uneconomical because the temperature of the water at the entrance to the first part 601 of the economizer specifies the lower temperature level, except for which heat can be extracted from the exhaust gas 53. The feed water line points therefore downstream of the feed water preheater 10 a branch at which the second quantity of feed water 72 is branched off and via at least one further - in the present example three - feed water preheaters 11, 12, 13 to be led. The steam turbine is used to heat the feed water Tapped steam mass flows 79, 80 and 81 are taken, which via the shut-off and control elements 22, 23 and 24 are set, and thus the Determine the temperature of the preheated feed water 72. About these Temperature and the shut-off and control elements 14 and 15 can be the water 73 can be set to the boiling point after the economizer.

In a further operating case, the additional firing 605 becomes a fuel 44 fed and burned, which adds further heat to the process. Because of the arrangement of the additional firing in the heat recovery steam generator acts Additional firing directly affects steam production. So it will be Steam production and thus the water / steam mass flow of the Water / steam cycle increased by operating the auxiliary firing. The water / steam mass flow can be increased until the Exhaust gas from the gas turbine as soon as it flows through the superheater Boiling temperature of the feed water reached.

With an increase in the live steam mass flow, the Temperature and / or the mass flow of the preheated Increase the amount of feed water 72 so that the water 73 exits the second part 602 of the economizer approximately at the boiling point is. As a result, the bleed steam mass flows 79, 80, 81 increased. This steam is no longer available to the steam turbine Labor turnover in the final stages is available, which is also an advantage has that especially with an increase in the steam mass flow Low pressure levels of the steam turbine are relieved. This eliminates the Need the low pressure stages and the flash floods for the full Dimension steam mass flow, which is significant investment saves.

Another operating case arises when the combination system is optionally available with two Fuels, for example with gas and oil, can be operated. When a the first fuel 41, which is supplied, is gas, so this is expedient Feed water introduced into the economizer at a temperature that the Water vapor contained in the exhaust gas is not condensed on the pipes. The first quantity of feed water 71 is then, for example, the one above 60 ° C quoted in the first part of the economizer. If as Fuel 41 is now supplied with oil, the temperature in the economizer be raised to the precipitation of organic components or of Sulfuric acid and therefore corrosion damage to the boiler pipes avoid. According to the higher feed water temperature is now a smaller heat exchanger area in the economizer is also necessary. Therefore the shutoff and control member 14 is closed in oil firing, and the total amount of feed water flows through the preheaters 11, 12 and 13, which Amount of feed water 72 is now at a temperature of, for example Preheat 130 ° C. By using the preheaters 11, 12 and 13, the Feed water preheater 10 operated with steam 78 which is relatively strongly expanded and does not have to be excessively large. The Feedwater preheaters 11, 12 and 13 can be a larger one if necessary Use a driving temperature gradient for preheating the feed water.

Incidentally, this has to be done with very strongly preheated feed water Care is taken to ensure that the economizer does not heat up above the Boiling point occurs. From this, the designer gains an important one Design criterion for the division of the heat exchanger surface of the Economizers in the first part 601 and the second part 602.

Further performance enhancement potential is through water or Steam injection into the hot gas of the gas turbine. 2 is one Another preferred embodiment of the combination system according to the invention shown. The boiler 6 is designed as a single-tube boiler. At a Single-tube boilers are live steam superheaters and evaporators not so accurate separately, we in the drum kettle shown in Fig. 1. The expert will nonetheless recognize the position where the additional firing in the Heat recovery steam generator is to be arranged to take advantage of the invention to take full advantage of. It is advantageous to choose a position downstream of which - seen in the direction of flow of the gas turbine exhaust gas - in all Operating states working medium of the steam turbine in liquid Physical state inside the boiler tubes.

In the embodiment shown here, there is further potential for Performance increase. A first tap of appropriate pressure on the Steam turbine is connected via a connecting line 28, in which a shut-off and control element 26, with the first combustion chamber 102 of the gas turbine connected is. Furthermore, a line 27 leads from a tap lower pressure via a shut-off and control element 25 to the second Combustion chamber 104 of the gas turbine. By introducing steam into the In particular, gas turbine can use more fuel 42, 43 with a high combined efficiency will be implemented. Furthermore, the mass flow of the expanded working medium 52 of the gas turbine, thereby reducing the steam production is increased again. Furthermore, the low pressure stages of the Steam turbine 4 relieved.

Of course, steam can be in different places in the water-steam cycle be removed. So saturated steam is suitable downstream of the evaporator 604, especially if one Steam cooling of the gas turbine components can be realized. This Tapping the water / steam cycle can still make sense if in the live steam superheater 606 not the total amount of steam generated can be overheated sufficiently high. The excess amount of saturated steam can then be expanded in the gas turbine, and the steam injection relieves the live steam superheater and the entire steam turbine. As well can also use superheated live steam for injection into the gas turbine Find use.

3 shows a circuit of the combination system with additional firing, which a particularly flexible adaptation of the mass flows to the Swallowing ability of various components and the possible ones Enthalpy flows in the heat recovery steam generator enabled. In a first Operating condition, without additional firing, are the shut-off and control elements 16, 26, 33 and 34 closed, and the shut-off and control elements 15, 22, 23, 24 are at least strongly throttled. Most of the feed water 71 flows through both sections 601 and 602 of the economizer while one smaller portion 72 preheated in the feed water preheaters 11 and 12 is that the temperature is almost the same as that of the first Amount of feed water 71 exiting the first section of the Economizers 601 is identical. The proportion of the preheated feed water 72 so that the temperature of the total feed water flow at the exit from the second part of the Economizers 602 is slightly below the boiling temperature. That warmed up Feed water is evaporated in the evaporator 604, in the live steam superheater 606 overheats, and the entire live steam 75 finally becomes the Steam turbine 4 fed and completely relaxed, with only small tapping mass flows 78, 79, 80 via the shut-off and control elements 21, 22 and 23 be removed from the steam turbine to be in the feedwater preheater 10 preheat the feed water 77 to such an extent that the Economizer tubing 601 does not form moisture, respectively as described above, the feed water partial stream 72 in the Suitable preheating feed water preheaters 11, 12. For The additional combustion 605 increases the output by a quantity of fuel 44 fed and burned. As a result, steam production increases Amount of feed water, and the amount of live steam. As a result, that too Shut-off and control element 15 opened further to the preheated To increase feed water mass flow 72. To the bigger one To preheat the amount of feed water, the steam turbine must be larger Tapping mass flows 79, 80 are removed, which relieves the last stages of the steam turbine leads to the corresponding amount of steam. At An increase in the feed water mass flow can occur that from a certain mass flow, the preheating of the partial flow 72 in the Preheaters 11 and 12 are no longer sufficient to exit the economizer To get water close to the boiling point. In this case the Feed water partial stream 72 is in turn divided into partial streams 721 and 722. This division is primarily controlled by the shut-off and control element 16. Its opening determines the partial flow 722, which is almost open in the preheater 13 Boiling temperature is heated, and therefore immediately in the embodiment is fed into the boiler drum 603. In the case of a single-tube boiler, the Partial flow 722 the remaining feed water mass flow, 71 and 721, are mixed upstream of the evaporator tube 604. At Steam production can continue to rise in a next step Steam injection control valves 25 and 26 of the gas turbine are opened, wherein the three-way valves 29, 30 are set such that the lines 27, 28 Steam is supplied as the partially expanded steam at a suitable stele Steam turbine is removed, which further relieves the Steam turbine low pressure stages leads. Through this measure, the Amounts of fuel 42 and 43 that are in gas turbine combustors 102 and 104 can be burned, increased without entering the temperature Turbines 103 and 105 increase. As a result, the gas turbine output increases and the exhaust gas mass flow 52 of the gas turbine. With a further increase the amount of steam it would be conceivable that the swallowing capacity of the High pressure part of the steam turbine is exhausted. In this case Shut-off and control element 34 opened, and the three-way valves 29 and 30 are switched. The gas turbine is thus now connected via line 32 Live steam supplied from the superheater outlet. So that Live steam production itself via the swallowing capacity of the steam turbine high-pressure part be increased. With a further increased Amount of fuel 44 that is supplied to the additional firing 605 is sufficient in Superheater 606 is no longer sufficient to transfer the amount of heat total steam generated to the required fresh steam temperature overheat. In this case, the shut-off and regulating element 34 finally becomes closed, and the shut-off and control member 33 opened. In the Gas turbine combustors 102 and 104 become saturated steam from line 31 injected, and already the live steam superheater from this amount of steam relieved. This embodiment shows how flexible the can design circuit of a combination system according to the invention.

The performance increase of the gas turbine and the possibility that Of course, increasing fuel quantities 42 and 43 also results if instead of Steam water is introduced into the combustion chambers. In this case, too the mass flow of the relaxed working medium 52 increases Gas turbine and thus the steam production in the waste heat boiler 6. This However, increased performance is at the expense of Profitability, since the heat of vaporization, which yes with the cooled Exhaust gas 53 is lost only through additional fuel supplied must be provided instead of, as is the case with steam injection is to be taken from the exhaust heat.

Finally, FIGS. 4 and 5 also show two circuit variants reheating 607. The steam turbine 4 is in a high pressure part 401 and a low pressure part 402 divided. a partially released steam quantity 82 from the high pressure part is in each case Intermediate superheater 607 led, from where reheated steam 83 in the Low-pressure part 402 of the steam turbine flows and is fully expanded there becomes. 4, the heat recovery steam generator 6 is shown as a drum boiler, in Fig. 5 as a single-tube boiler. The design of the heat recovery steam generator can be in the both figures can be exchanged for each other without the essence touch the invention in the slightest, as well as the different Place the feed of the preheated feed water 72 in the two Examples - once in the economizer and once in the boiler tubing immediately upstream of the evaporator - design variants that are in the Examples chosen to illustrate different possibilities were. On the other hand, the arrangement of the reheaters is in both Examples completely different.

4, the reheater 607 is parallel to the live steam superheater 606 led. On the one hand, this circuit results in the best possible System efficiency in nominal full load operation, on the other hand the Amount of steam at a limited within the superheater section of the Heat recovery steam generator usable heat to the design temperature can be overheated, limited. For this limitation of steam production results in a lower achievable increase in performance.

In contrast, the reheater 607 in FIG. 5 is parallel to the evaporator 604 arranged in the steam generator, such that the additional firing also on the reheater works. As a result, the steam is in nominal operation only slightly reheated without additional firing, and the nominal Efficiency is lower than in the circuit shown in Fig. 4. There but now the additional firing acts on the reheater pipe, more fuel can be sensibly fired. The one with additional firing increased reheat temperature is also equal Efficiency losses that occur with the additional firing, at least partially out. In this arrangement of the reheater is one constructive preferred variant, the piping of the reheater so to arrange that the evaporator pipe between the additional firing and the pipe of the reheater, and the heat transfer to the is driven purely by convection to superheating steam. By just being wet operated heat exchanger tubes from the radiant heat of the auxiliary firing is a much less expensive construction of the boiler possible.

Based on the exemplary embodiments, a small section of the broad Spectrum of designs in which the in the claims characterized invention can be realized. The interpretation of the Water / steam cycle with or without reheating, the arrangement of the reheater in the heat recovery steam generator and much more of specific requirements for the operation of the plant, of Conditions such as the exhaust gas mass flow and the exhaust gas temperature of the Gas turbine, and not least determined by the budget, whereby all the illustrated embodiments preferred variants adapted to the problem of the invention characterized in the main claim like the representation of the gas turbine as a gas turbine with sequential Combustion, in a single-shaft arrangement with the steam turbine, is allowed be interpreted restrictively that in the embodiment of Steam turbine process is described as a water-steam process. It can here also another one for the realization of the two-phase process suitable working medium can be used. It could also be the same with the gas turbine process is a closed process.

In this way, the average person skilled in the art depending on the specific task a variety of other circuit and Arrangement variants for the concrete execution of the in the claims marked subject of the invention suggests to represent the This disclosure is far beyond the scope of this disclosure.

Reference list

1

Gas turbine

2nd

generator

3rd

clutch

4th

Steam turbine

6

Heat recovery steam generator

7

capacitor

8th

Condensate and feed pump

9

Condensate and feed pump

10th

Feed water preheater

11

Feed water preheater

12th

Feed water preheater

13

Feed water preheater

14

Shut-off and control device

15

Shut-off and control device

16

Shut-off and control device

21

Shut-off and control device

22

Shut-off and control device

23

Shut-off and control device

24th

Shut-off and control device

25th

Shut-off and control element, steam injection control valve

26

Shut-off and control element, steam injection control valve

27

Connecting line

28

Connecting line

29

Three-way valve

30th

Three-way valve

31

Connecting line

32

Connecting line

33

Shut-off and control device

34

Shut-off and control device

41

fuel

42

first amount of fuel

43

second amount of fuel

44

Amount of fuel for re-firing

51

Intake air of the gas turbine

52

relaxed working medium of the gas turbine

53

cooled exhaust gas

71

Feed water quantity, feed water pipe

72

Feed water quantity, feed water pipe

73

Heated (boiling) water

74

Saturated steam, steam pipe

75

(superheated) live steam, steam pipe

76

relaxed steam

77

Feed water, main feed water volume

78

Draw steam quantity

79

Draw steam quantity

80

Draw steam quantity

81

Draw steam quantity

82

partially relaxed steam

83

partially overheated steam

101

compressor

102

first combustion chamber

103

first turbine

104

second combustion chamber

105

second turbine

401

High pressure part of the steam turbine

402

Low pressure part of the steam turbine

601

first part of the economizer

602

second part of the economizer

603

Boiler drum

604

Evaporator, evaporator tubing

605

Additional firing

606

Live steam superheater

607

Reheater

721

Feed water partial flow

722

Feed water partial flow

Claims (21)

Combined system, consisting of at least one gas turbine (1), at least a steam turbine (4) and at least one heat recovery steam generator (6), which heat recovery steam generator has at least one evaporator (604) and includes a live steam superheater (606), and which one Heat recovery steam generator in operation from a relaxed working medium (52, 53) of the gas turbine and from a working medium (71, 72, 73, 74, 75) the steam turbine is flowed through in counterflow, thereby characterized in that an additional firing in the heat recovery steam generator (605) in the flow direction of the relaxed working medium Gas turbine downstream of the live steam superheater of the Heat recovery steam generator is arranged. Combined system according to claim 1, characterized in that the Heat recovery steam generator is designed as a single-tube boiler. Combined system according to claim 1, characterized in that the Heat recovery steam generator is designed as a drum boiler. Combined system according to claim 1, characterized in that the Additional firing between the live steam superheater and one Evaporator (604) of the heat recovery steam generator is arranged. Combined system according to claim 1, wherein in the heat recovery steam generator Economizer is arranged, characterized in that in the water-steam cycle a first downstream of the feed pump (8.9) Feed water preheater (10) is arranged, downstream of which the Feed water pipe is branched, from which branch starting a first feed water line (71) to the most downstream of the Flow of the relaxed working medium of the part located in the gas turbine des Economizers (601), and at least one more Feed water line (72) via at least one other Feed water preheater (11, 12, 13) to a further upstream Section (602) of the economizer, and / or immediately into one Boiler drum (603) or an evaporator (604) is guided. Combined system according to claim 5, characterized in that everyone Feed water preheater (10, 11, 12, 13) with a tapping point of the Steam turbine is connected. Combined system according to claim 5, characterized in that each Feed water line (71, 72) each with at least one shut-off and Control element (14, 15, 16) is provided. Combined system according to claim 1, characterized in that in the Circuit of the working medium of the steam turbine downstream of one Condenser (7) two pumps of the same power (8, 9) are arranged, one of which is used to operate the combination system without additional firing enough. Combined system according to claim 1, characterized in that a Reheater (607) for a partially relaxed working medium Steam turbine is arranged in the heat recovery steam generator. Combined system according to claim 9, characterized in that the for Tubing of the reheater belonging to the heat recovery steam generator (607) and the pipe belonging to the heat recovery steam generator Evaporator (604) at an identical position in the heat recovery steam generator are arranged. Combined system according to claim 1, characterized in that a shaft a gas turbine (1) with a generator (2) for generating electricity is connected, and the same generator via an automatically acting Coupling (3) is connected to a shaft of a steam turbine (4). Combined system according to claim 1, characterized in that at least a connecting line (27, 28) from a tap of the steam turbine in a combustion chamber (102, 104) and / or a turbine (103, 105) of the Leads gas turbine, and that this connecting line with a shut-off and control element (25, 26) is provided. Combined system according to claim 1, characterized in that at least a connecting line (31, 32) from the boiler (6) and / or one Steam line (74,75,82,83) into a combustion chamber (102, 104) and / or Turbine (103, 105) of the gas turbine leads, and that this connecting line is provided with a shut-off and control element (33, 34). Combined system according to claims 12 and 13, wherein steam from both Tapping points of the steam turbine as well as tapping points on the boiler and / or the steam lines of the gas turbine can be fed, thereby characterized in that to switch the supply of steam from the various branches of the steam supply three-way valves (29.30) in the connecting lines are installed. Combined system according to one of claims 12 to 14, characterized characterized that steam for cooling is thermally highly stressed Gas turbine components is used. Combined system according to claim 1, characterized in that the Gas turbine over at least two with respect to the flow of the Working medium in series-connected combustion chambers (102, 104), a turbine (103) being arranged between each two combustion chambers and a last turbine (105) downstream of a last combustor is arranged. Combined system according to claim 1, characterized in that the Temperature of the relaxed working medium (52) of the gas turbine at Full load operation of the gas turbine is above 580 ° C. Method for operating a combination system according to claim 1, characterized characterized in that the gas turbine in a first operating point their full load operating point works, and the waste heat boiler with one Nominal mass flow of exhaust gas, the Water / steam mass flow is dimensioned such that the temperature of the Exhaust gas when leaving the evaporator (604) approximately the Boiling temperature of the feed water corresponds, and that to increase the Power output of the steam turbine the additional firing in operation is taken, which acts directly on the evaporator, in such a way that the steam production increases. A method according to claim 18, characterized in that a Main feed water quantity (77) is divided into two partial flows (71, 72), that a first partial flow (71) via a first feed water line is fed directly to a first section (601) of an economizer, and that at least one further partial flow, which in the economizer or in the boiler drum or the evaporator of the heat recovery steam generator first partial stream is mixed in at least one preheater (11, 12, 13) is heated so that the temperature of the whole Water mass flow (73) when entering the evaporator area (603, 604) approximately corresponds to the boiling temperature of the feed water. A method according to claim 18, characterized in that for Preheating the steam turbine feed water at least one Steam quantity (79, 80, 81) at at least one intermediate tapping point is removed. The method of claim 18, wherein oil is used as fuel (41), characterized in that the first feed water line is shut off is, and that another partial stream is preheated to a temperature which is above the dew point temperature of sulfuric acid.

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