CN103717846A - Additional controlled extraction for preheater for improving the plant dynamics and the frequency regulation in steam power plant - Google Patents

Abstract

The invention relates to a steam extraction method for a preheater of a steam power plant and a water-steam circuit in the steam power plant. According to the invention, high-energy steam is extracted on a turbine of a steam power plant and mixed into low-energy steam extracted on the turbine. Supplying a steam mixture of low-energy steam and admixed high-energy steam to a preheater of a steam power plant, in particular to a high-pressure preheater, especially to the last high-pressure preheater stage of a high-pressure preheater, in particular to heat the Heater feed water. Through the controlled admixture of high-energy steam (controlled extraction) with low-energy steam, especially in closed-loop and/or open-loop control, especially at part load of the steam power plant, a medium-power adjustment of the steam power plant can be achieved by changing the temperature of the low-energy steam Change quickly.

Description

Additional controlled steam extraction for preheaters for improved plant dynamics and frequency control in steam power plants

technical field

The invention relates to a steam extraction method for a preheater, in particular for a high pressure preheater of a steam power plant, especially a coal-fired power plant, and to a water-steam circuit in a steam power plant .

Background technique

Furthermore, steam or thermal power plants are known, for example, from the following Internet address: http://de.wikipedia.org/wiki/Dampfkraftwerk (accessed 22 June 2011).

A steam power plant is a type of power plant for generating electricity from fossil fuels in which the thermal energy of water vapor is converted into kinetic energy in a steam turbine and further into electrical energy in a generator.

In this steam power plant, the steam required for operating the steam turbine is first generated in a steam boiler from generally previously cleaned and prepared water (feed water). By further heating the steam in the superheater, the temperature and specific volume of the steam increase.

From the steam boiler, the steam flows through the pipes into the steam turbine, where the steam outputs part of its previously acquired energy to the turbine. A generator is coupled to the turbine, which converts the mechanical power into electrical power.

The depressurized and cooled steam then flows into a condenser where it is condensed by heat transfer to the environment and collected as liquid water.

Thus, the water is intermediately stored in the feed water container through the condensing pump and the preheater, and then supplied to the steam boiler again through the feed water pump, thereby closing the circuit.

Steam power plants are divided into different types, for example into coal-fired power plants, oil-fired power plants, combined gas and steam power plants (GuD power plants).

Coal-fired power plants are a special type of steam power plant in which coal is used as the main fuel to generate steam. Such coal-fired power plants are known for lignite as well as stone coal.

In this coal-fired power plant, according to the described general circuit of a steam power plant, lignite or stone coal is first ground in a coal mill and dried. The lignite or stone coal is then blown into the combustion chamber of a pulverized coal burner (staubfeuerung) and completely combusted there. The heat thus released is absorbed by the water tube boiler and converts the supplied water (feed water) into steam.

The water vapor flows through the pipes to the steam turbine, where the water vapor transfers part of its energy to the turbine as kinetic energy through depressurization. The mechanical power is then converted by means of a generator coupled to the turbine into electrical power, which is fed into the grid as electrical current.

Usually, a condenser is arranged below the turbine, in which the steam transfers the greatest part of its heat to the cooling water after being unpressurized in the turbine. During this process, the steam liquefies through condensation.

The feedwater pump closes the circuit by conveying the formed liquid water back into the water tube boiler as feedwater.

All information occurring in a steam or coal-fired power plant, such as measured values, process data or status data, is displayed in a console and evaluated here usually in a central computer, where it is displayed, evaluated, controlled, regulated and/or controlled The operating status of individual power plant components.

Through the control mechanism, power plant personnel can intervene in the operating process of the coal-fired power plant, for example by opening or closing solenoid valves or valves, or by changing the amount of fuel delivered.

The central component of this console is the computer on which the unit control system (blockf ü hrung), central regulation and control and/or control units are implemented, whereby the control, regulation and control of steam or coal-fired power plants can be carried out and/or control.

In deregulated electricity markets, flexible load operation of power plants and devices for frequency control in the grid are increasingly important for power plant operation.

In terms of frequency control of the grid there are different types of frequency control, eg primary control and secondary control with or without so-called dead bands.

Since electrical energy cannot be stored on the way from producer to consumer, generation and consumption must be balanced within the grid at all times, ie the electrical energy must be delivered exactly in the amount consumed. The frequency of the electrical energy is the overall controlled quantity here, and as long as generation and consumption are in balance the network frequency nominal value is used. The rotational speed of the power plant generators connected to the grid is synchronized with this grid frequency.

If a power generation deficit occurs in the grid at a certain point in time, this deficit is firstly filled by the energy contained in the flywheel of the rotating machine (turbine, generator). As a result, the machine is braked, and thus the rotational speed of the machine and thus the (network) frequency is further reduced.

If this network frequency reduction is not overcome by suitable power or frequency control within the grid, it will lead to grid collapse.

In the dead band mentioned, normally no control intervention takes place in the range of small frequency deviations up to ±0.07 to 0.1 Hz. In this region only a slow response control with a delay can be realized to compensate for the existing deviations between production and consumption.

Larger frequency deviations in the range of 0.1 to 3.0 Hz, for example due to power plant faults and fluctuations in consumption, are divided over the entire grid by the primary control for the power plants involved in the primary control. For this purpose, a so-called primary control reserve is provided, ie a power reserve that is automatically supplied to the grid by the participating electric fields in order to thus compensate for imbalances between production and consumption within a second by controlling production.

The primary control thus serves to stabilize the network frequency to the smallest possible deviation, but at a level different from the predetermined network frequency target value.

The task of the secondary control connected to the primary control is to further create a balance between generation and consumption within the grid and thus return the grid frequency to a predetermined frequency nominal value, eg 50 Hz.

To this end, the power plants participating in the secondary control provide a secondary control reserve in order to return the network frequency to the network frequency nominal value and to create a balance within the grid again.

The requirements of the primary control and the output of the primary control reserve to the grid are automatically realized by the power plant control devices participating in the primary control (this grid or the frequency change in the grid requires the primary control reserve), while the secondary control is arranged in the upper level through the grid The network controllers of are required at the power plants participating in the primary control and are then output by the power plants into the grid under this requirement.

In part, frequency control reserves for power plants as well as primary and/or secondary control reserves are obligatory in certain cases given by national regulations; control reserves provided by power plants are usually provided as special grid services to generating The factory will provide compensation.

It is of course economically attractive to participate in frequency control or non-baseload operation for large modern cogeneration plants with supercritical steam generators usually operating in baseload operation. With the retrofitting of renewable energies (wind energy), the requirements for controllability even for large power plant units tend to be sharpened.

It is also known that, in contrast to pumped-storage power plants or gas-fired power plants in which power is available on the order of a second when required, for example in the case of frequency control the required power of a coal-fired power plant from an arbitrary power point The power rise is significantly slower ("power inertia").

The cause of this "power inertia" in coal fired power plants is the "thermal inertia" of the fuel coal. That is, a change in coal combustion results in a change in the power of the coal-fired power plant (either a change in the real power of the coal-fired power plant or a change in the separated thermal power (process steam) ), which is primarily due to the time-consuming coal supply and crushing process. Power and power boosts, as in the case of a control reserve, can therefore only be provided with a time delay into the respective grid or distribution network.

Although, the power slopes or power gradients operable by coal-fired power plants in this way are moderate, the interconnection conditions must meet the transmission regulations currently in force in Germany (minimum requirements), e.g. required primary control reserve.

As long as higher frequency reserves and primary and/or secondary control reserves are realized in coal-fired power plants than are at least required by national regulations, this leads to correspondingly higher profitability for coal-fired power plant operators.

Furthermore, some countries, depending on the size of the network and the structure of the generating units, require higher power gradients or frequency control reserves on a case-by-case basis than are required for the interconnection of their networks. For example, UK grid codes require a 10% power boost within 10 seconds.

To accelerate power changes in frequency and primary and/or secondary control in the case of coal-fired power plants, it is known to use fast-acting additional measures (“Flexible Load Operation and Frequency Support for Steam Turbine Power Plants”, Wichtmann et al., VGB PowerTech7 /2007, pp. 49-55), the additional measures are based on the use of energy contained in the process medium of a coal-fired power plant, ie feedwater or steam, such as throttling of the high-pressure turbine control valve, overload introduction of the high-pressure section turbine, condenser Blockage, bypass of the feed water side of the high pressure preheater and throttling of the extraction steam line to the high pressure preheater.

Of course, the inherent energy storage of this process medium is limited, so that the control reserve available thereby is also limited. Furthermore, the operating range within which frequency control can be achieved is correspondingly limited.

Furthermore, combustion disturbances are known to occur in steam power plants or coal-fired power plants, which lead to uneven plant operation. Here, the task is to balance out these disturbances or operating fluctuations in order to stabilize the plant operation and optimize the plant dynamics.

Usually, the balance of this disturbance or fluctuation is achieved by changing the combustion accordingly. That is, the amount of control that causes disturbance is used to balance the disturbance. This balance also results in jerky equipment operation.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and a device for improving the dynamic plant performance of a steam power plant, in particular a coal-fired power plant. The technical problem to be solved by the invention is also to improve the frequency control in steam or coal-fired power plants, in particular to improve the power change speed and/or the power range, ie the power control reserve.

The technical problem is solved by a method for extracting steam from a preheater, especially a high-pressure preheater, especially of a steam power plant of a coal-fired power plant, and especially a steam power plant of a coal-fired power plant, with the features according to the independent claims The water-steam circuit in is realized.

According to the method according to the invention, high-energy steam is drawn off at the turbine of the steam power plant and mixed into the low-energy steam drawn off at the turbine.

Here, the relative terms "high" and "low" are understood to mean respectively relative to the two extracted steam. Therefore, the extracted mixed steam is more energetic than the extracted steam mixed with high energy steam. Thus, for example, the drawn-in steam has a higher pressure and/or a higher temperature than the drawn-in steam to be mixed in.

In this case, the live steam flowing into the turbine or into the high-pressure turbine can be used as upwardly limited as entrained energy-rich steam. In connection with this, steam extraction at the turbine is also understood to mean extraction of steam not only directly at the turbine/turbine inlet or at the high-pressure turbine/high-pressure turbine inlet, but also in a live steam line leading into the turbine or into the high-pressure turbine.

A steam mixture of low-energy steam and admixed high-energy steam is supplied to a preheater of a steam power plant, in particular a high-pressure preheater, in particular to heat the feedwater flowing through the preheater. In particular, the supply to the last high-pressure preheater stage takes place.

Through the especially closed-loop and/or open-loop controlled admixture of high-energy steam into low-energy steam (controlled steam extraction), especially in power-controlled operation of steam power plants, a rapid power increase in steam power plants can be achieved by changing the temperature of low-energy steam Change. In particular, when the invention is used continuously during plant operation, the combustion is not tracked accordingly in the event of combustion disturbances, as is usually the case, but the smoothness of operation of the plant can be improved by means of the invention.

Controlled extraction here means precisely metering the mixture of extracted high-energy steam to extracted low-energy steam by open-loop/closed-loop control, for example by precisely controlling the flow rate of extracted high-energy steam. As a control quantity for this control, the Economizer inlet temperature or the feed water temperature can be used. Open-loop/closed-loop can be implemented here in the unit control system of the plant.

In the water-steam circuit of the steam power plant according to the invention, the turbine and in particular the preheater of the high-pressure preheater are arranged in the water-steam circuit.

This preheater is known as a high pressure preheater or a low pressure preheater. Usually, a plurality of these high-pressure or low-pressure preheaters are each constructed as successive (preheating) stages, wherein the feedwater (high-pressure preheater) or condensate (low-pressure preheater) guided here is heated by means of multiple Each (temperature) level is carried out.

In addition, the first steam extraction line is connected to the turbine, so that high-energy steam can be extracted from the turbine through the first steam extraction line. The second steam extraction pipeline is also connected to the turbine, and the low-energy steam can be extracted from the turbine by the second steam extraction pipeline.

The first and second extraction lines are connected by a mixing device, such as a simple line connection element, with which the high-energy steam from the first extraction line and the low-energy steam from the second extraction line can be mix.

A supply line is connected to the mixing device and the preheater, with which the steam mixture consisting of high-energy steam and low-energy steam can be supplied to the preheater, especially to the high-pressure preheater, especially to the final high-pressure preheater stage, especially to heat the feedwater flowing through the preheater.

Here, the last high-pressure preheater stage refers to the high-pressure preheater after which the feedwater from the preheating finally leaves and is fed to the steam generator.

In short, the invention proposes to mix the high-energy steam extracted on the turbine into the low-energy steam extracted on the turbine, wherein the energy of the low-energy steam is increased, especially its temperature and pressure. The steam mixture is used in particular to heat the high-pressure preheater or feed water which is led through the high-pressure preheater.

In particular, heating takes place in the last high-pressure preheater stage (also called highest high-pressure preheater stage).

Through the participation of several or all high-pressure preheaters, corresponding temperature gradients can be defined and thus ensure a corresponding protective mode of operation of the plant. In other words, here a plurality of controlled extractions according to the invention are provided for at least the last high-pressure preheater, if necessary for several or all high-pressure preheaters.

The open-loop/closed-loop controlled mixing of high-energy steam into low-energy extraction steam (controlled extraction) enables rapid and targeted power changes of the plant, especially in part-load operation of the plant, by increasing the temperature of the extraction steam . In relation to this, "rapid" is understood to mean that the power is increased within a short time, ie a large positive power gradient is experienced. "Targeted" here means an open-loop/closed-loop controlled change of the power to a predetermined power state.

In this case, a power change or a power increase can be required in the frequency control and the primary and/or secondary control of a steam power plant, in particular a coal-fired power plant, or in the case of combustion disturbances in a steam power plant.

Thus, the power boost can in particular be in the range of 2% to 15% of the nominal power, especially preferably in the range of 2% to 10% thereof.

This increase in power is especially established within a time range of 5 to 600 seconds, especially preferably within a time range of 5 to 30 seconds. The additional power may then be maintained during at least a further period of time in the range of 5 to 50 minutes, especially during a period of 5 to 30 minutes.

The unit control system performs open-loop/closed-loop control through the inlet temperature of the "economizer" or the final temperature of the feed water as the control quantity of the open-loop/closed-loop control.

The invention has proven to be clearly advantageous in several respects.

The invention makes it possible to improve the dynamic plant performance and the frequency control in a steam power plant, in particular a coal-fired power plant, in an advantageous manner and in an advantageously simple manner.

In particular, in combination with known measures for accelerating power changes in frequency control and primary and/or secondary control in coal-fired power plants, frequency control and primary and/or secondary control can thus be amplified by the invention scope. The smooth running of the plant can also be improved by means of the invention. In particular, when the invention is continuously used, the combustion is not tracked accordingly in order to compensate for small combustion disturbances, as is usually the case.

Through the participation of several or all high-pressure preheaters, corresponding temperature gradients can be limited and thus ensure a correspondingly protective system operating mode.

Preferred developments of the invention also result from the respective subclaims. The described extensions relate to methods as well as devices.

According to a preferred refinement, the high-energy steam and the low-energy steam are extracted from the same turbine part of the turbine, in particular from a high-pressure part or a medium-pressure part of the turbine.

It can also be proposed to heat the feedwater in the high-pressure preheater, in particular in the last high-pressure preheater stage, or also the condensate in the low-pressure preheater, by using the steam mixture.

In a further preferred development, the mixing of high-energy steam into low-energy steam is controlled closed-loop and/or open-loop, in particular by means of the unit control system of the steam power plant and in particular by using the "economizer" inlet temperature or feedwater final temperature The closed-loop and/or open-loop control takes place as a control variable.

Furthermore, the invention can be proposed for raising the temperature and/or the pressure of the extracted low-energy steam, wherein by mixing high-energy steam into the low-energy steam, the temperature is increased especially up to about 20 Kelvin and/or the pressure is increased High especially up to about 5 bar.

The invention can also be used for the rapid, targeted power increase of steam power plants, especially steam power plants operated at part load, the power increase being brought about by a temperature increase of extracted low-energy steam.

Furthermore, the invention can be used in frequency control in steam power plants, especially in secondary and/or primary control, where by mixing high-energy steam into low-energy steam results in frequency control, especially secondary and/or rapid power changes of the power change of the steam power plant required in the primary control, and/or enlarge the frequency control range in the steam power plant by mixing the high energy steam into the low energy steam, especially the primary and / or secondary control scope.

Furthermore, the invention can be used to increase the smoothness of operation in steam power plants in which combustion disturbances are achieved by rapid power changes, balanced by closed-loop and/or open-loop controlled mixing of high-energy steam to low-energy steam.

The invention can also be used in addition to power boosting in steam power plants by using the energy contained in the process medium of the steam power plant, in particular in addition to throttling of the high-pressure turbine control valve, introduction of overload to the high-pressure part turbine, Condenser blockage, high pressure preheater feedwater side bypass and/or throttling of extraction steam line to high pressure preheater for other uses.

The invention can also be used sustainably in the operation of steam power plants, in particular in part-load operation, to compensate for combustion disturbances in the steam power plant.

In a further preferred development, the water-steam circuit and/or the mixing device has an open-loop/closed-loop control device, which is implemented in particular in the unit control system of the steam power plant, with the open-loop/closed-loop control device, in particular It is possible to control the mixture of high energy steam and low energy steam in closed loop and/or open loop by using "economizer" inlet temperature or feed water final temperature as the control quantity.

In addition, according to a particularly preferred development, it can be proposed that the water-steam circuit consists of at least two units each consisting of a first extraction steam line, a second extraction steam line, a mixing device and a supply line, and that at least two Each of the units supplies a steam mixture to a preheater, especially a high pressure preheater.

It can furthermore be provided here that the second extraction steam line of the first unit is also the first extraction steam line of the second unit. In this way, a cascade-like supply of the steam mixture can be realized, which reduces the need for additional lines.

With particular preference a plurality of such units can be provided, the plurality or all of the high-pressure preheaters, but at least the last high-pressure preheater stage being supplied with the respective steam mixture. Through the participation of several or all high-pressure preheaters, corresponding temperature gradients can be limited and thus ensure a corresponding protective mode of operation of the plant.

Furthermore, a steam power plant, especially a coal-fired power plant, having a water-steam circuit according to the invention can be provided.

Description of drawings

An exemplary embodiment of the invention is illustrated in the drawing, which is explained in further detail.

Each picture is:

Figure 1 shows a water-steam loop in a coal-fired power plant according to an embodiment of the invention,

Fig. 2 shows a detail part (HD turbine part) of the water-steam circuit according to Fig. 1,

FIG. 3 shows a further detail (MD turbine section) of the water-steam circuit according to FIG. 1 .

Detailed ways

Example: Additional Controlled Extraction for High Pressure Preheater to Improve Plant Dynamics and Frequency Control in Steam Power Plants (Coal Fired Power Plants) ( FIGS. 1 to 3 ).

Fig. 1 and Fig. 2 and Fig. 3 show the water-steam circuit of the coal-fired steam power plant 1 and its details.

In this coal-fired steam power plant 1 (coal-fired power plant 1 for short), lignite and stone coal are ground and dried in a coal mill according to the usual coal combustion. The lignite and stone coal are then blown into the combustion space of a pulverized coal burner (staubfeuerung) and completely burned there.

The heat thus released is absorbed by the water tube boiler (shortly referred to as steam generator 2 ) and converts the fed water (feed water) 3 into steam/high pressure steam 4 .

The high-pressure steam 4 generated in the steam generator 2 enters the high-pressure part 11 of the steam turbine 10 and performs mechanical work there by depressurization and cooling.

In order to achieve a high overall efficiency, the steam, after leaving the high-pressure part 11 , is conducted again into the steam generator 2 and is superheated. The superheated steam is fed to the turbine 10 again in the double-flow intermediate pressure section 12 and further performs mechanical work by further depressurization and cooling.

After leaving the medium-pressure section 12, the steam flows into two low-pressure sections 13, 14 of the steam turbine 10, each of double-flow configuration, where it performs further mechanical work by decompression and cooling to the exhaust pressure level .

The mechanical power is then converted into electrical power by means of a generator 20 coupled to the turbine 10 , which is fed into the grid 21 in the form of electrical current.

Exhaust steam from the turbine is condensed in the condenser 30 with the aid of primary cooling water. The main condensate that occurs is supplied by the main condensate pump to the low-pressure (ND)-preheater 40 and to the feed water container 50 and here in the preheating stage 42 in the form of the turbine 10 and from the turbine 10 respectively with two The extraction steam 41 of the low pressure part 13, 14 of dual flow configuration is preheated.

Two feed water pumps take the required feed water 51 from the feed water container 50 and supply this feed water 51 back to the steam generator 2 by increasing the pressure and further heating in the high pressure (HD)-preheater 60 . The extraction steam 61 from the turbine 10 and the extraction steam 61 from the turbine 10 as well as from the high-pressure part 11 and the intermediate-pressure part 12 of the turbine 10 are used again for heating.

In order to achieve a high overall efficiency, the preheating path formed by ND preheaters 40 and HD preheaters 60 is designed in multiple stages with a plurality of ND preheaters 42 and HD preheaters 62 in each case.

2 and 3 show that HD-preheaters 60 , 62 , 63 , 64 , 65 are supplied with extraction steam 61 ( FIG. 2 ) from the high-pressure part 11 of the turbine 10 and with two-flow medium-pressure Extraction steam 78, 79 and 95 of section 12 (Fig. 3).

As shown in FIG. 2 , steam 75 , 76 , 77 is extracted (extracted) from the turbine 10 at three locations 71 , 72 , 73 respectively in the high-pressure part 11 of the turbine 10 .

High-energy extraction steam 75 of the turbine 10 is led off at a first extraction location 71 close to the inlet location 74 into the high-pressure part 11 of the turbine 10, said high-energy extraction steam 75 being controllably provided by a controlled flow controller 80 To the low energy steam 76 extracted at the second extraction position 72 compared to the high energy extraction steam 75 . This steam mixture 78 or this extraction steam 78 is supplied to the last high-pressure preheater stage 63 of the HD-preheater 60 in order to preheat the feed water 51 .

As further shown in FIG. 2 , the extraction steam 76 taken at the second extraction location 72 of the turbine 10 or the high pressure stage 11 of the turbine 10 is controllably supplied to the third extraction location 72 via a controlled flow controller 80 . Compared with the extraction steam 76 , low-energy steam 77 is drawn from the steam point 73 . This steam mixture 79 or this extraction steam 79 is supplied to the penultimate high-pressure preheater stage 64 of the HD-preheater 60 in order to preheat the feed water 51 .

As shown in FIG. 3 , steam 93 , 94 is also extracted (extracted) at two points 91 , 92 of the medium-pressure part 12 of the turbine 10 .

By means of this first extraction point 91 leading off the extraction steam 93 of the turbine 10 , said extraction steam 93 is provided (via the controlled flow controller 80 ) in a controlled manner to the . Steam 94 of low energy compared to said extraction steam 93 . This steam mixture 95 or this extraction steam 95 is supplied to the high-pressure preheater stage 65 of the HD preheater 60 upstream of the two high-pressure preheater stages 63 and 64 in order to preheat the feed water 51 .

The open-loop/closed-loop control of the mixture is carried out through the controlled flow controller 80 through the unit control system of the equipment, and the final temperature of the feed water is used as the control quantity of the open-loop/closed-loop control.

The flow conduction of the fluid takes place via a complex line 82 or a complex pipe system 82 , which additionally provides a barrier for the flow conduction within the scope of the controlled steam extraction.

Therefore, the high-pressure and high-temperature controlled extraction steam (75 to 76) and (76 to 77) and (93 to 94) are respectively provided here for the use of the three high-pressure preheater stages 63, 64 and 65, at least for The highest high pressure preheater stage 63 is used. Through the energy-rich controlled steam extraction, a temperature increase of up to approximately 20 Kelvin and a pressure increase of up to approximately 5 bar are achieved in each steam mixture.

Through this open-loop/closed-loop control, the high-energy steam 75, 76, 93 is mixed into each low-energy extraction steam 76, 77, 94 (the mixing method is: 75 to 76; 76 to 77; 93 to 94), especially in coal-fired During part-load operation of the power plant 1 , a rapid and targeted power change of the plant is achieved by changing the temperature of the extraction steam.

The participation of several or all high-pressure preheaters, in this case high-pressure preheater stages 63 , 64 , 65 , can limit the corresponding temperature gradients and thus ensure a corresponding protective system operating mode.

Thus, dynamic equipment performance and frequency control in coal-fired power plants can be improved in an efficient and simple manner.

Thus, in combination with known measures for accelerating power changes in frequency control and primary and/or secondary control in coal-fired power plants, for example the frequency control range and the primary and/or secondary control range can be enlarged. In particular if this measure is used continuously, the operating stability of the plant can also be improved in this way to compensate for small combustion disturbances without correspondingly following the combustion, as is usually the case.

Claims (15)

1. one kind for the method for drawing gas of the preheater of the especially high pressure pre-heater of the steam power station of coal-fired power plant especially, it is characterized in that, on the turbo machine of steam power station, extract high energy steam and be blended into the low energy steam extracting on turbo machine, and the vapour mixture being comprised of low energy steam and the high energy steam of sneaking into is provided to the preheater of steam power station, especially high pressure pre-heater, especially so that the feedwater of preheater is flow through in heating.

2. according at least one the method that the described control for preheater is drawn gas in aforementioned claim, it is characterized in that, described high energy steam and described low energy steam, in the identical turbo machine part of described turbo machine, especially extract on the high-pressure section of described turbo machine or intermediate pressure section.

3. according at least one the method that the described control for preheater is drawn gas in aforementioned claim, it is characterized in that, by using feedwater in high pressure preheat stage especially last in described vapour mixture heating high-pressure preheater or the condensed water in low pressure preheater (LPP.

4. according at least one described method in aforementioned claim, it is characterized in that, closed loop and/or open loop control ground are carried out, especially by the unit control system of steam turbine and especially by being used as " economizer " inlet temperature of controlled quentity controlled variable or feeding water final temperature closed loop and/or open loop control and carry out described high energy steam to the mixing of low energy steam.

5. according at least one described method in aforementioned claim, temperature and/or the pressure of described method for raising low energy steam extracted, wherein, by high energy steam being blended into low energy steam, temperature has been raise and especially up to about 20, opened and/or pressure has been raise especially up to about 5 bar.

6. according at least one described method in aforementioned claim, described method changes for quick, the autotelic power of steam power station, the steam power station that especially moves in partial load, wherein, described power change causes by the temperature rising institute of the low energy steam of extraction.

7. according at least one described method in aforementioned claim, described method is for the FREQUENCY CONTROL of steam power station, especially secondary and/or primary control, wherein by high energy steam being blended into low energy steam, caused the power of and/or primary control desired steam power station especially secondary for FREQUENCY CONTROL to raise fast, and/or by described high energy steam being blended into described low energy steam, amplify the refrequency control range in steam power station, especially amplified elementary and/or secondary control range.

8. according at least one described method in aforementioned claim, described method is for improving the running stability of steam power station, and wherein the burning in steam power station disturbs the fast power of sneaking into realization by being controlled to closed loop and/or the open loop of low energy steam by high energy steam to change and balance.

9. according at least one described method in aforementioned claim, described method is except using the power that raises in steam power station by contained energy in using the process medium of steam power station, especially remove the throttling of high pressure turbine control valve, overload to high-pressure section turbo machine is introduced, coagulator stops up, the feedwater side of high pressure pre-heater detours and/or leads to outside the throttling of the steam line that draws gas of high pressure pre-heater and especially in its partial load run, uses constantly the in service of steam power station, burning with steam power station described in balance is disturbed.

10.Yi Zhong steam power station is the water-steam-return line in coal-fired power plant especially, with being arranged in turbo machine in water-steam-return line and with being arranged in especially high pressure pre-heater of preheater in water-steam-return line, it is characterized in that, described water-steam-return line has:

The-the first bleed steam pipework, described the first bleed steam pipework is connected with described turbo machine, and can on described turbo machine, extract high energy steam with described the first bleed steam pipework,

The-the second bleed steam pipework, described the second bleed steam pipework is connected with turbo machine, and can on described turbo machine, extract low energy steam with described the second bleed steam pipework,

-the mixing apparatus that connects with the first and second bleed steam pipeworks, can be by the high energy steam from described the first bleed steam pipework with from the low energy vapor mixing of described the second bleed steam pipework with described mixing apparatus, and

-the supply pipeline that is connected with described preheater with described mixing apparatus, with described supply pipeline, the vapour mixture by high energy steam and low energy vapour composition can be provided to preheater and especially be provided to high pressure pre-heater, especially so that the feedwater of preheater is flow through in heating.

11. according to the water-steam-return line described at least aforementioned claim, it is characterized in that, described water-steam-return line and/or described mixing apparatus have the open/close control apparatus in the unit control system that is especially implemented in steam power station, using described open/close control apparatus especially by using " economizer " inlet temperature or feedwater final temperature to control the mixing of high energy steam and low energy steam as controlled quentity controlled variable energy closed loop and/or open loop.

12. according at least one described water-steam-return line in aforementioned claim, it is characterized in that, described water-steam-return line has at least two unit that consist of described the first bleed steam pipework, described the second bleed steam pipework, described mixing apparatus and described supply pipeline respectively, and use at least two unit each supply with each vapour mixture for preheater especially high pressure pre-heater.

13. according at least one described water-steam-return line in aforementioned claim, it is characterized in that, described second bleed steam pipework of first module is also described first bleed steam pipework of second unit.

14. according to the water-steam-return line described in claim 12 or 13, and described water-steam-return line is with a plurality of unit, and a plurality of or whole high pressure pre-heaters are given in described a plurality of unit, but at least last high pressure pre-heater level provides with each vapour mixture.

15.Yi Zhong steam power station, especially coal-fired power plant, described steam power station is with according to claim 10 at least one described water-steam-return line in 14.

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