JP2018025113A - Turbine control device, turbine control method, and extraction steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control a temperature of steam of an extraction steam turbine such as extraction steam or non-extraction steam.SOLUTION: According to a first embodiment, a turbine control device controls an extraction steam turbine comprising: at least one turbine driven by steam; a first valve controlling first steam before introduction into the turbine; and a second valve extracting a part of second steam introduced into the turbine as third steam and causing another part of the second steam to be further used in the turbine as fourth steam. The device comprises a restricting curve provision section providing at least one restricting curve for representing a state of the first steam by using a temperature and a flow rate of the first steam as variables, and restricting extraction operation of the extraction steam turbine based on the state of the first steam. The device further comprises a control section controlling the second valve so as to execute the extraction operation when the state of the first steam is positioned within a first region defined by the restricting curve.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a turbine control device, a turbine control method, and an extraction steam turbine.

  The extraction steam turbine is a turbine that can use steam for power generation and heat supply. Specifically, the extraction steam turbine is driven by the steam flowing in the extraction steam turbine, generates power with a generator, extracts steam from an intermediate stage of the extraction steam turbine, and supplies the extraction steam to the outside. To do. For example, the extracted steam is supplied as a steam for production to a surrounding factory, or is supplied as a steam for heating to a surrounding area. Thus, the extraction steam turbine can supply both electricity and heat.

  Typically, the main steam flow, bleed steam flow, and generator output of the bleed steam turbine are manually adjusted by a power plant operator according to a steam consumption curve that is predetermined during turbine design. The main steam flow rate can be adjusted by a main steam control valve for supplying steam to the extraction steam turbine. The extraction steam flow rate can be adjusted by an extraction steam control valve for extracting steam from an intermediate stage of the extraction steam turbine. The set value of the main steam flow rate at which in-service of the extraction operation can be performed is set by the above-described steam consumption curve, and the extraction operation cannot be in-service when the main steam flow rate is less than the set value.

  On the other hand, recently, customers are demanding diversification of operation of extraction steam turbines. For example, there is a demand for extraction operation for extracting a large amount of steam from an extraction steam turbine even during low load operation with a small main steam flow rate. Thus, in the operation of the extraction steam turbine, the demand for the power generation amount may not match the demand for the extraction steam amount. In this case, in order to reduce the generator output, it is necessary to reduce the main steam flow rate by restricting the main steam control valve. However, if the main steam flow rate is decreased, the steam temperature upstream of the extraction steam control valve becomes higher than the limit temperature, and the extraction operation may not be performed.

  The extraction steam turbine includes, for example, a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine. In this case, the extraction steam turbine is driven by the flow of steam in the order of the high-pressure turbine, the medium-pressure turbine, and the low-pressure turbine, and the generator generates power. For example, the main steam control valve is disposed upstream of the high pressure turbine, and the extraction steam control valve is disposed between the high pressure turbine and the intermediate pressure turbine.

  FIG. 9 is a state diagram for explaining the operation of a conventional extraction steam turbine. FIG. 9 shows an example of the bleed operation during the low load operation of the bleed steam turbine with an enthalpy-entropy diagram.

FIG. 9 shows isotherms such as a curve CT and isobaric lines such as a curve CP when the horizontal axis is entropy and the vertical axis is enthalpy. Point K ₁ (and point K ₃ ) represents the state of steam at the inlet point of the high-pressure turbine, and corresponds to the state of steam flowing upstream of the main steam control valve. Point K ₂ (and point K ₄ ) represents the state of steam at the outlet point of the high-pressure turbine, and corresponds to the state of steam flowing upstream of the extraction steam control valve. The symbol P ₁ represents the steam pressure at the point K ₁ . Reference numeral _{P 2} represents the pressure of the vapor at point _{K 2.} Symbols T ₁ , T ₂ , and T _X represent steam temperatures.

In order to reduce the power generation amount of the generator, it is necessary to reduce the main steam flow rate by reducing the opening of the main steam control valve. However, when the opening degree of the main steam control valve is reduced, the valve pressure loss due to the main steam control valve increases. Therefore, the entry point of the high pressure turbine moves from point K ₁ to the point K _3, the main steam pressure is reduced.

On the other hand, the extraction steam is supplied to the outside of the extraction steam turbine while the extraction steam pressure is controlled to be constant by the extraction steam control valve. Therefore, when the main steam flow rate at the entrance point of the high-pressure turbine is reduced, the exit point of the high-pressure turbine moves over isobar from point K ₂ to the point K _4. For example, in terms K ₂ before reduction of the main steam flow rate, steam temperature upstream of the extraction steam control valve is T _1. On the other hand, in terms K ₄ after reduction of the main steam flow rate, steam temperature upstream of the extraction steam control valve is increased to T _2, the steam pressure upstream of the bleed steam control valve is maintained at P _2.

Here, representing the limit temperature of the steam extraction steam turbine T _X. Reducing the main steam flow concentrates main steam control valve during low-load operation, as shown in FIG. 9, the steam temperature upstream of the extraction steam control valve is likely to be higher than the limit temperature T _X. In this case, the steam temperature of the extraction steam is higher than the limit temperature T _X, it is impossible to in-service bleed operation. Limiting the temperature T _X, for example, steam pipes of the extraction steam turbine, turbine blades, is defined by the material and the heat resistance of the turbine rotor and other components.

JP-A-2-283802

  If the extraction steam is supplied from the extraction steam turbine to the outside during the low load operation, the steam temperature upstream of the extraction steam control valve may reach the limit temperature. In this case, there is a problem that the steam temperature of the extracted steam becomes higher than the limit temperature, and the extraction operation cannot be performed in service.

  Further, when the extraction operation is performed with a small main steam flow rate, the steam flow rate of the non-extraction steam that flows through the flow path after the extraction stage of the extraction steam turbine decreases, and the steam temperature of the non-extraction steam rises. For example, the exhaust steam temperature of a medium pressure turbine or a low pressure turbine rises. Therefore, when performing the extraction operation at the time of low load operation, there is a possibility that the steam temperature of the non-extraction steam flowing through the flow path after the extraction stage reaches the limit temperature.

  Therefore, it is expected to provide a turbine control device that appropriately controls the steam temperature of extracted steam and non-extracted steam and enables in-service of the extraction operation during low-load operation. This is considered to greatly contribute to the customer's expectation of diversified operation of the extraction steam turbine.

  Then, embodiment of this invention makes it a subject to provide the turbine control apparatus, turbine control method, and extraction steam turbine which can control appropriately the temperature of steam, such as extraction steam of an extraction steam turbine, and non-extraction steam. .

  According to the first embodiment, the turbine control device is configured to control at least one turbine driven by steam, a generator driven by the turbine, and the first steam before being introduced into the turbine. A second valve for extracting a part of the second steam introduced into the turbine as the third steam and further using another part of the second steam as the fourth steam in the turbine; An extraction steam turbine comprising: The apparatus expresses the state of the first steam using the temperature and flow rate of the first steam as variables, and at least for restricting the extraction operation of the extraction steam turbine based on the state of the first steam. A limiting curve providing unit that provides one limiting curve is provided. The apparatus further includes a control unit that controls the second valve so as to perform the extraction operation when the state of the first steam is located in a first region defined by the limit curve.

It is a mimetic diagram showing the composition of the power plant of a 1st embodiment. It is a state figure for explaining the 1st example of operation of the extraction steam turbine of a 1st embodiment. It is a state figure for explaining the 2nd example of operation of the extraction steam turbine of a 1st embodiment. It is a graph for demonstrating operation | movement of the extraction steam turbine of 1st Embodiment. It is a graph for demonstrating operation | movement of the extraction steam turbine of 2nd Embodiment. It is a graph for demonstrating operation | movement of the extraction steam turbine of 3rd Embodiment. It is a schematic diagram for demonstrating operation | movement of the power plant of 4th Embodiment. It is a graph for demonstrating operation | movement of the extraction steam turbine of 5th Embodiment. It is a state figure for explaining operation of the conventional extraction steam turbine.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 9, the same or similar components are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
Drawing 1 is a mimetic diagram showing the composition of power plant 1 of a 1st embodiment.

FIG. 1 shows a power plant 1 according to the present embodiment and an external plant 2 outside the power plant 1. The power plant 1 includes a boiler 11, an extraction steam turbine 12, and a plant control device (plant DCS) 13. The external plant 2 includes an extracted steam utilization mechanism 21 and a plant control device 22. FIG. 1 further shows flow paths L _{1 to} L ₅ that carry water or steam.

  The extraction steam turbine 12 includes a high-pressure turbine 31, an intermediate-pressure turbine 32, a low-pressure turbine 33, a turbine rotor 34, a generator 35, a condenser 36, a main steam stop valve (MSV) 41, and main steam. A control valve (CV) 42, a bleed steam control valve (ECV) 43, a main steam thermometer 44, a high-pressure turbine thermometer 45, an intermediate-pressure turbine thermometer 46, and a turbine controller (D-EHC) 47 It has. The high-pressure turbine 31, the intermediate-pressure turbine 32, and the low-pressure turbine 33 are examples of at least one turbine. The main steam control valve 42 is an example of a first valve, and the extraction steam control valve 43 is an example of a second valve.

Boiler 11 generates a high-pressure steam to heat the water from the flow path L _1, the flow path (main steam flow path) L ₂ for discharging steam (main steam). The main steam flow path L ₂ includes a main steam stop valve 41 that controls supply and stop of the main steam, a main steam control valve 42 that controls the flow rate of the main steam, and a main steam thermometer that measures the temperature of the main steam. 44. The temperature measurement result by the main steam thermometer 44 is output to the turbine controller 47. Main steam is introduced into the high-pressure turbine 31 from the main steam flow path L _2. Main steam flowing through the main steam flow path L ₂ is an example of the first steam.

The steam introduced into the high-pressure turbine 31 works in the high-pressure turbine 31 and then flows into the exhaust part of the high-pressure turbine 31. The exhaust section of the high-pressure turbine 31 includes an extraction steam chamber and an extraction steam system nozzle connected from the extraction exhaust chamber. Vapor in the high pressure turbine 31 is exhausted to the flow path L ₃ as an exhaust steam from the exhaust unit, bled into the flow path L ₅ as the extracted steam through the nozzle from the extraction steam chamber. Exhaust steam flows into the intermediate-pressure turbine 32 from the flow path L _3. The steam in the high-pressure turbine 31 is an example of the second steam. Extracted steam is an example of third steam. Exhaust steam (non-extracted steam) is an example of the fourth steam.

The flow path L ₃ is extraction steam control valve 43 for controlling the flow rate of the extraction steam is provided. When the opening degree of the extraction steam control valve 43 is increased, the flow rate of the extraction steam decreases. On the other hand, if the opening degree of the extraction steam control valve 43 is decreased, the flow rate of the extraction steam increases. During the extraction operation of the extraction steam turbine 12, the opening degree of the extraction steam control valve 43 is controlled so that the pressure of the exhaust steam upstream of the extraction steam control valve 43 becomes constant.

  The high-pressure turbine thermometer 45 is provided in the high-pressure turbine 31 and measures the temperature of the steam at the casing outlet of the high-pressure turbine 31. This temperature corresponds to an example of the temperature of the second steam or the temperature of the fourth steam upstream of the extraction steam control valve 43 (second valve). The temperature measurement result by the high-pressure turbine thermometer 45 is output to the turbine controller 47.

Steam flowing into the intermediate pressure turbine 32, after working at medium within pressure turbine 32 is discharged to the flow path (cross-over pipe) L _4. The vapor flows from the crossover pipe L ₄ to the low pressure turbine 33. The steam that has flowed into the low-pressure turbine 33 works in the low-pressure turbine 33 and is then discharged to the condenser 36 that is kept in vacuum. The condenser 36 returns the steam to water (condensate) by heat exchange between the steam and the cooling water. Condensate accumulates in the hot well of the condenser 36.

  The intermediate pressure turbine thermometer 46 is provided in the intermediate pressure turbine 32 and measures the temperature of the steam at the casing outlet of the intermediate pressure turbine 32. This temperature corresponds to an example of the temperature of the fourth steam downstream of the extraction steam control valve 43 (second valve). The temperature measurement result by the intermediate pressure turbine thermometer 46 is output to the turbine controller 47.

  The extraction steam turbine 12 is driven by steam flowing in the high-pressure turbine 31, the intermediate-pressure turbine 32, and the low-pressure turbine 33, and rotates the turbine rotor 34. The generator 35 generates power by being driven by the rotation of the turbine rotor 34.

On the other hand, the extracted steam flowing through the flow path L ₃ is supplied to the extracted steam utilization mechanism 21 in the external plant 2. An example of the extracted steam utilization mechanism 21 is a facility that uses the extracted steam for production, industrial process, heating, and the like. The external plant 2 may be a power plant or another plant. The plant control device 22 in the external plant 2 controls the operation of the extraction steam utilization mechanism 21 and transmits information about the extraction steam utilization mechanism 21 to the turbine control device 47.

  The turbine controller 47 controls various operations of the extraction steam turbine 12. The turbine control device 47 controls, for example, opening / closing of the main steam stop valve 41, opening of the main steam control valve 42, opening of the extraction steam control valve 43, and the like. On the other hand, the plant control device 13 in the power plant 1 controls various operations of the power plant 1, for example, controls the operation of the boiler 11. The turbine control device 47 can control the operation of the boiler 11 via the plant control device 13. Conversely, the plant control device 13 can control the operation of the extraction steam turbine 12 via the turbine control device 47. Examples of the plant control device 13 and the turbine control device 47 are computers and processors.

  Thus, the extraction steam turbine 12 of this embodiment performs a power generation operation and an extraction operation. However, when the extraction steam turbine 12 is in-service during the low load operation, the temperature of the steam in the high-pressure turbine 31 is reduced by reducing the opening of the main steam control valve 42 as described with reference to FIG. In addition, there is a problem that the temperature of the extracted steam or the exhaust steam from the high-pressure turbine 31 becomes high. In this case, there is a possibility that the extraction operation cannot be performed in-service. Hereinafter, this problem and its solution will be described in detail.

  FIG. 2 is a state diagram for explaining a first example of the operation of the extraction steam turbine 12 of the first embodiment.

In the first example, the above problem is addressed by lowering the main steam temperature as compared with the case of FIG. As a result, the points K _{1 to} K ₄ are replaced with points K ₁ ′ to K ₄ ′, respectively. Point K ₁ ′ (and point K ₃ ′) represents the state of steam at the inlet point of the high-pressure turbine 31, and corresponds to the state of steam flowing upstream of the main steam control valve 42. At the point K ₁ ′, the temperature of the main steam to the high-pressure turbine 31 is decreased compared to the point K ₁ . Point K ₂ ′ (and point K ₄ ′) represents the state of steam at the outlet point of the high-pressure turbine 31, and corresponds to the state of steam flowing upstream of the extraction steam control valve 43.

In this case, when the opening degree of the main steam control valve 42 is reduced to reduce the main steam flow rate, the inlet point of the high-pressure turbine 31 moves from the point K ₁ ′ to the point K ₃ ′, and the main steam pressure decreases. On the other hand, the extracted steam is extracted while the extracted steam pressure is controlled to be constant by the extracted steam control valve 42. Therefore, when the main steam flow rate at the inlet point of the high-pressure turbine 31 decreases, the outlet point of the high-pressure turbine 31 moves on the isobaric line from the point K ₂ ′ to the point K ₄ ′.

Here, the point K ₄ and the point K ₄ ′ are compared. Steam temperature at point _{K 4 (T 2)} is higher than the limit temperature _{T X.} Therefore, when the opening degree of the main steam control valve 42 is reduced as shown in FIG. 9, the bleed operation cannot be in-service. On the other hand, the steam temperature at point K _{4 'is} lower than the limit temperature T _X. Therefore, when the opening degree of the main steam control valve 42 is reduced as shown in FIG. 2, the extraction operation can be in-service.

As described above, in the first example, by lowering the main steam temperature in comparison with the case of FIG. 9, it is adjusted lower than the limit temperature T _X steam temperature at point K _{4 '.} A specific method of determining the steam temperature value at the point K ₄ ′ will be described later.

  FIG. 3 is a state diagram for explaining a second example of the operation of the extraction steam turbine 12 of the first embodiment.

In the second example, when the opening degree of the main steam control valve 42 is reduced and the main steam flow rate is reduced, the amount of decrease in the main steam flow rate is reduced as compared with the case of FIG. . As a result, points K ₁ and K ₂ are maintained, while points K ₃ and K ₄ are replaced by points K _{5 to} K ₆ , respectively.

In this case, reducing the aperture main steam flow rate the degree of opening of the main steam control valve 42, the entry point of the high-pressure turbine 31 is moved from the point K ₁ to the point K _5, the main steam pressure is reduced. On the other hand, the extracted steam is extracted while the extracted steam pressure is controlled to be constant by the extracted steam control valve 42. Therefore, when the main steam flow rate at the entrance point of the high pressure turbine 31 is reduced, the exit point of the high-pressure turbine 31 is moved on the isobar from point K ₂ to the point K _6.

Here, comparing the point _{K 4} and the point _{K 6.} Steam temperature at point _{K 4 (T 2)} is higher than the limit temperature _{T X.} Therefore, when the opening degree of the main steam control valve 42 is reduced as shown in FIG. 9, the bleed operation cannot be in-service. On the other hand, steam temperature _{(T 3)} of the point _{K 6} is lower than the limit temperature _{T X.} Therefore, when the opening degree of the main steam control valve 42 is reduced as shown in FIG. 3, it is possible to in-service the extraction operation.

As described above, in the second embodiment, by reducing the amount of reduction of the main steam flow as compared with the case of FIG. 9, it is adjusted lower than the limit temperature T _X steam temperature at point K _6. It will be described later specific method of determining the value of the steam temperature at point K _6.

  FIG. 4 is a graph for explaining the operation of the extraction steam turbine 12 of the first embodiment.

FIG. 4 shows a coordinate plane for representing the state of steam for the extraction steam turbine 12 by its steam temperature and steam flow rate. FIG. 4 further shows bleed operation limit curves C _{1 to} C ₃ that are held by the turbine control device 47 and used during the bleed operation. This function of the turbine controller 47 is an example of a limiting curve provider. In addition, the bleed operation restriction curves C _{1 to} C ₃ are examples of at least one restriction curve. Hereinafter, the extraction operation restriction curves C _{1 to} C ₃ are simply referred to as “restriction curves C _{1 to} C ₃ ”.

The limiting curves C _{1 to} C ₃ are curves for expressing the steam state using the steam temperature and the steam flow rate as variables and limiting the bleed operation based on the steam state. The turbine control device 47 controls whether or not the extraction operation is restricted during the low load operation of the extraction steam turbine 12 based on the restriction curves C _{1 to} C ₃ . This function of the turbine control device 47 is an example of a control unit.

Steam flow rate limit curve _C 1 -C ₃ takes a constant value below the temperature _{T A,} increases with steam temperature at the temperature _T A through T _B, takes a constant value at higher temperature _{T B.} At the temperature T _A , the steam flow rates of the restriction curves C _{1 to} C ₃ are F _{A1 to} F _A3 , respectively. In the temperature _{T B,} the steam flow rate limit curve _C 1 -C ₃ are each _F B1 _{to F B3.}

Here, limit curve C ₁ is a curve to specify a condition suitable in-service bleed operation. Limit curve C ₂ is a curve for defining the generation of warning. Limit curve C ₃ is a curve to define the stopping of the service. 4, limit curve C ₂ is located in the lower limit curve C _1, limit curve C ₃ is located below the limit curve C _2.

Figure 4 further includes an upper region _{R 0} of the limit curve _{C 1,} a region _{R 1} between the limit curve _C 1, _{C 2,} a region _{R 2} between the limit curve _C 2, _{C 3,} limit curve C ₃ shows a region R ₃ below. Region R ₀ and region R ₁ are examples of the first region. Region _{R 2} is an example of the second region. Region _{R 3} is an example of the third region. As described above, the coordinate plane of FIG. 4 is divided into four regions R _{0 to} R ₄ by the _three limiting curves C _{1 to} C ₃ .

The turbine control device 47 controls the extraction operation based on the state of the main steam at the inlet of the high-pressure turbine 31. For example, the main steam state when located within or in the region R ₁ region R ₀ is performing the bleed operation. Further, the main steam state when positioned within the region R _2, while running the extraction operation, and outputs a warning about the extraction steam turbine 12. Further, when the main steam state is positioned within the region R ₃ limits the bleed operation (e.g., discontinuation). The execution and limitation of the extraction operation are controlled by adjusting the opening degree of the extraction steam control valve 43. Details of these processes will be described later.

(Restriction curves C _{1 to} C ₃ and regions R _{0 to} R ₄ )
With continued reference to FIG. 4, details of the restriction curves C _{1 to} C ₃ and the regions R _{0 to} R ₄ will be described.

The turbine control device 47 controls the operation of the extraction steam turbine 12 according to the limit curves C _{1 to} C ₃ in order to enable in-service of the extraction operation during the low load operation of the extraction steam turbine 12. The restriction curves C _{1 to} C ₃ are used to control the main steam temperature and the main steam flow rate at the inlet of the high-pressure turbine 31 when the extraction steam turbine 12 performs the power generation operation and the extraction operation simultaneously. This main steam temperature can be measured by a main steam thermometer 44. The limit curves C _{1 to} C ₃ are incorporated in the turbine control device 47, and the operation of the extraction steam turbine 12 is performed by the turbine control device 47 while the extraction steam turbine 12 performs the power generation operation and the extraction operation. It is automatically controlled.

The bleed operation at the time of low load operation is limited by the limit curves C _{1 to} C ₃ . For example, when the steam temperature is T _B, when the steam flow rate is reduced to F _B3, extraction operation is limited by the limit curve C _3. On the other hand, when the steam temperature is T _A , even if the steam flow rate decreases to F _B3 , the bleed operation is not limited by the limit curve C ₃ until the steam flow rate reaches F _A3 . Therefore, the turbine controller 47 can relax the restriction on the steam flow rate by reducing the main steam temperature, that is, by controlling from the point K ₁ to the point K ₁ ′ in FIG. 2.

Further, the steam flow rate in the case of F _A1 before the steam temperature rises to T _B, extraction operation is limited by the limit curve C _3. On the other hand, if the steam flow rate is F _B3 are, until the vapor temperature rises to T _B, the extraction operation is not limited by limit curve C _3. Therefore, the turbine controller 47, an increase in the main steam flow rate, i.e., the control of the point K ₃ in FIG. 3 to point K _5, it is possible to relax the restrictions on steam temperature. This can be realized by increasing the opening degree of the main steam control valve 42.

Main steam conditions (i.e., the operating point of the extraction steam turbine 12) If is in or in the region R ₁ region R _0, the extraction steam turbine 12 is capable of continuous operation of both the power operation and bleed operation. On the other hand, if the operating point is within the region R _2, is continued to bleed operation, there is a possibility that the steam temperature at the outlet of the high pressure turbine 31 is increased up to the limit temperature T _X.

Therefore, the turbine controller 47, when the operating point is detected that enters the region R ₂ outputs the alarm to the operator, in response to manual operation of the operator main steam control valve 42 Increase the opening of. By the latter control, the main steam flow rate can be increased and the steam temperature at the outlet of the high-pressure turbine 31 can be lowered. Examples of the former alarm include an alarm by sound using an alarm buzzer, an alarm by light using an alarm lamp, and an alarm by screen display using an alarm display terminal. In this case, the operator may select manual operation of the extraction steam turbine 12.

Further, when the operating point is within the region R _3, the turbine controller 47, thereby fully open the bleed steam control valve 43 to stop the in-service bleed operation. As a result, the pre-pressure of the extraction steam control valve 43 is greatly reduced, and the steam temperature at the outlet of the high-pressure turbine 31 is reduced.

However, stopping the in-service of the bleed operation has a large disturbance to the bleed system. Therefore, the turbine controller 47, when the operating point is within the region R _2, the operating point is to increase the degree of opening of the main steam control valve 42 in order to prevent from reaching the region R _3. This makes it possible to avoid the in-service cancellation of the bleed operation as much as possible.

As described above, the turbine control device 47 of the present embodiment uses the relationship between the steam state and the regions R _{0 to} R ₄ defined by the restriction curves C _{1 to} C ₃ to execute or restrict the extraction operation. To control. Therefore, according to the present embodiment, the temperature of the steam can be appropriately controlled during the extraction operation of the extraction steam turbine 12. Further, according to the present embodiment, it is possible to appropriately determine whether to perform or restrict the in-service of the extraction operation when performing the power generation operation and the extraction operation during the low load operation.

(Second Embodiment)
FIG. 5 is a graph for explaining the operation of the extraction steam turbine 12 of the second embodiment.

When the extraction steam turbine 12 performs the power generation operation and the extraction operation at the same time, the main steam temperature and the main steam flow rate at the inlet of the high-pressure turbine 31 are automatically controlled by the turbine controller 47 according to the limit curves C _{1 to} C _3. The

  However, the extraction steam flow rate may change abruptly during operation of the extraction steam turbine 12. For example, when the extraction steam flow rate decreases, the main steam flow rate is reduced in order to keep the generator output constant.

In this case, the main steam condition (operating point of the extraction steam turbine 12) is changed, it can deviate from the region R ₀ and region R _1. As shown in FIG. 5, when the state of the temperature and flow rate of the main steam enters the region R _2, if left such a change in operating point, to deviate the operating point is further from the region R _2, the region R There is a risk that the air will enter ₃ and the bleed operation may be stopped.

Therefore, as a method for returning the operating point to the region R ₀ without using an operator in order to continue the bleed operation, the turbine control device 47 has the operating points in the regions R ₀ and R ₁ within the region R ₂ . When entering is detected, the main steam temperature or the main steam flow rate is changed so that the operating point returns to the regions R ₀ and R ₁ . Specifically, in this case, the turbine controller 47 automatically increases the opening of the main steam control valve 42 to increase the output of the extraction steam turbine 12. As a result, the main steam flow rate increases, and the operating point returns to the regions R ₀ and R ₁ as indicated by the arrow α ₁ . Or, by reducing the main steam temperature upstream of the extraction steam control valve 43, the operating point returns to the region R _0, R ₁ as indicated by an arrow alpha _2. Thus, it is possible to continue the operation at the upper limit curve C _1.

As described above, according to the present embodiment, the state of the main steam can be returned from the region R ₂ to the regions R ₀ and R ₁ by controlling the opening degree of the main steam control valve 42, and the extraction operation is stopped. It is possible to prevent such restrictions.

(Third embodiment)
FIG. 6 is a graph for explaining the operation of the extraction steam turbine 12 of the third embodiment.

  The horizontal axis and the vertical axis in FIG. 6 represent the temperature measurement time and the measurement temperature by the high-pressure turbine thermometer 45, respectively. The high-pressure turbine thermometer 45 is provided in the vicinity of the casing outlet of the high-pressure turbine 31, and can measure the steam temperature in the extraction steam chamber of the high-pressure turbine 31, for example.

Figure 6 illustrates a measurement temperature _{Y 1} at time _{X 1,} and the measurement temperature _{Y 2} at time _{X 2,} and the expected temperature _{Y 3} at time _{X 3.} Figure 6 further shows the maximum temperature Y _L of extraction steam chamber of the steam of the high pressure turbine 31. Upper limit temperature Y _L indicates the temperature of the limit curve C ₂ in FIG. Therefore, when the steam temperature rises above the upper limit temperature _{Y L,} the vapor state enters the region _R 0, _{R 1} in the region _{R 2.}

The turbine control device 47 can detect the rate of change of the steam temperature in the extraction steam chamber based on the measured temperatures Y ₁ and Y ₂ at times X ₁ and X ₂ . Specifically, since the steam temperature is increased by 50 ° C. in 30 seconds, the current rate of change of the steam temperature is 100 ° C./min. This function of the turbine control device 47 is an example of a detection unit.

Next, the turbine controller 47 calculates the estimated temperature _{Y 3} time _{X 3} of 60 seconds after the time _{X 2.} The rate of change of the current steam temperature, the expected temperature Y ₃ is expected to be higher 100 ° C. than the measurement temperature Y _2. Therefore, beyond the upper limit temperature Y _L steam temperature within 60 seconds, the state of vapor is expected to enter the region R _2.

Therefore, the turbine controller 47, when the state of the extraction steam chamber of the steam within a predetermined time (in this case the 60 seconds) is expected to enter the region R _2, the state of the vapor from the region R ₂ The steam temperature or flow rate is varied away from it. Specifically, in this case, the turbine controller 47 automatically increases the opening of the main steam control valve 42 to increase the output of the extraction steam turbine 12. As a result, the main steam flow rate is increased, the state of the extraction steam chamber of the steam away from the area R ₂ without entering the region R _2. Furthermore, it is possible to avoid an increase in steam temperature in the extraction steam chamber or upstream of the extraction steam control valve 43.

As described above, according to this embodiment, the opening control of the main steam control valve 42, the state of the extraction steam chamber of a steam becomes possible to prevent from entering the region R _2, the extraction operation It is possible to prevent restrictions such as canceling the program.

  Although the third embodiment is applied to the control of steam in the extraction steam chamber, it may instead be applied to the control of main steam as in the second embodiment. In this case, the temperature on the vertical axis in FIG. 6 is replaced with the temperature measured by the main steam thermometer 44. Similarly, the second embodiment is applied to the control of the main steam, but instead, may be applied to the control of the steam in the extraction steam chamber as in the third embodiment. In this case, the temperature on the horizontal axis in FIG. 5 is replaced with the temperature measured by the high-pressure turbine thermometer 45. The same applies to the fifth embodiment described later.

(Fourth embodiment)
FIG. 7 is a schematic diagram for explaining the operation of the power plant 1 of the fourth embodiment.

  When the main steam flow rate is decreased by reducing the opening degree of the main steam control valve 42, the steam temperature upstream of the extraction steam control valve 43 may be higher than the design upper limit value. Further, when a large amount of extracted steam is supplied to the outside by the extracted steam control valve 43, the temperature of the non-extracted steam after the extraction stage of the extracted steam turbine 12 rises, and the consumption rate of the creep life of the extracted steam turbine 12 increases. Will speed up.

  Therefore, the turbine controller 47 monitors the temperature change of the steam in the intermediate pressure turbine 32 based on the temperature measurement result by the intermediate pressure turbine thermometer 46. The turbine controller 47 outputs an alarm for the extraction steam turbine 12 when the temperature of the steam exceeds the limit temperature of the intermediate pressure turbine 32 (FIG. 7). Examples of alarms are alarms by sound using the alarm buzzer 51, alarms by light using the alarm lamp 52, alarms by screen display using the alarm display terminal 53, and the like, for example, occur in the central control room. The turbine control device 47 controls alarm output via the plant control device 13. Note that the alarm of this embodiment can also be applied to the alarm of the first embodiment.

  The operator may select manual operation of the extraction steam turbine 12 in response to the alarm, and may manually decrease the extraction steam flow rate, or may manually increase the main steam flow rate. In order to prompt the operator to decrease the extraction steam flow rate or increase the main steam flow rate, an alarm indicating that the extraction steam temperature is high may be output to the operator. In this case, the operator may increase the opening degree of the extraction steam control valve 43 or may increase the opening degree of the main steam control valve 42.

Further, the turbine controller 47, when the state of the steam enters the region R ₃ may output different alarm and alarm region R _2. In this case, for example, an alarm indicating that the extraction operation is to be stopped is output from the alarm buzzer 51, the alarm lamp 52, or the alarm display terminal 53. In this case, the operator stops the extraction operation with a protective device for manually stopping the extraction operation of the extraction steam turbine 12.

(Fifth embodiment)
FIG. 8 is a graph for explaining the operation of the extraction steam turbine 12 of the fifth embodiment.

  The turbine control device 47 of the present embodiment monitors the temperature change of the steam in the extraction steam chamber of the high-pressure turbine 31 based on the temperature measurement result by the high-pressure turbine thermometer 45. Further, the turbine controller 47 detects the difference between the previous measured temperature and the current measured temperature as the amount of change in the steam temperature in the extraction steam chamber. This function of the turbine control device 47 is an example of a detection unit.

  Next, the turbine control device 47 predicts the next temperature measured by the high-pressure turbine thermometer 45. The next measured temperature is expected to change from the current measured temperature by the amount of change described above.

Therefore, the turbine controller 47, when the state of the extraction steam chamber of the steam is expected to enter the region R ₂ at the next temperature measurement, as the state of the vapor away from the region R _2, the steam Change the temperature or flow rate. Specifically, in this case, the turbine controller 47 automatically decreases the output of the boiler 11 to decrease the main steam temperature, and further increases the opening of the main steam control valve 42 to increase the main steam flow rate. Increase. As a result, while away the state of the extraction steam chamber of a steam from the area R _2, it is possible to reduce the main steam temperature, thereby enabling continuous operation of both the power operation and bleed operation. The turbine control device 47 controls the output of the boiler 11 via the plant control device 13.

Further, the turbine controller 47, the area that the state of the extraction steam chamber of the steam entering the region R ₂ at the next temperature measurement instead be predicted from the amount of change, when the temperature measurement state of this extraction steam chamber of a steam that it has entered the R ₂ may be detected from the current measured temperature. In this case, when the turbine controller 47 detects that the state of the steam in the extraction steam chamber has entered the region R ₂ at the time of the current temperature measurement, the steam control unit 47 returns the steam state to the regions R ₀ and R ₁ . The temperature or flow rate is changed (see symbols β ₁ and β ₂ in FIG. 8). In the present embodiment, as described above, the main steam temperature is decreased or the main steam flow rate is increased, so that the steam temperature in the extraction steam chamber is decreased, and the state of the steam is returned to the regions R ₀ and R ₁ . it can.

The control of the state of the steam is performed when the state of the extraction steam chamber of the steam is expected to enter the region R ₂ is also the same as the control in Fig. In this case, the state of the steam is changed away from the area R ₂ a decrease of the steam temperature.

As described above, according to this embodiment, by controlling the operation of the boiler 11, and to return the state of the extraction steam chamber of a steam from the region R ₂ in the region R _0, R _1, be kept away from the region R ₂ It becomes possible, and it becomes possible to prevent restrictions, such as cancellation of bleed operation.

1: power plant, 2: external plant,
11: Boiler, 12: Extraction steam turbine, 13: Plant control device,
21: Extracted steam utilization mechanism, 22: Plant control device,
31: High-pressure turbine, 32: Medium-pressure turbine, 33: Low-pressure turbine,
34: Turbine rotor, 35: Generator, 36: Condenser,
41: Main steam stop valve, 42: Main steam control valve, 43: Extraction steam control valve,
44: main steam thermometer, 45: high-pressure turbine thermometer,
46: Medium pressure turbine thermometer, 47: Turbine controller,
51: Alarm buzzer, 52: Alarm lamp, 53: Alarm display terminal

Claims (9)

At least one turbine driven by steam;
A generator driven by the turbine;
A first valve for controlling the first steam before being introduced into the turbine;
A second valve for extracting a part of the second steam introduced into the turbine as a third steam and further using another part of the second steam as a fourth steam in the turbine;
A turbine control device for controlling an extraction steam turbine comprising:
The state of the first steam is expressed using the temperature and flow rate of the first steam as variables, and at least one restriction for restricting the extraction operation of the extraction steam turbine based on the state of the first steam A curve, a limiting curve providing unit that provides a curve,
A controller that controls the second valve so as to execute the extraction operation when the state of the first steam is located in a first region defined by the limit curve;
A turbine control device comprising:   The control unit controls the second valve so as to execute the extraction operation when the state of the first steam is located in a second region defined by the limit curve, and the extraction steam is controlled. The turbine control device according to claim 1 which outputs an alarm about a turbine.   The control unit controls the second valve so as to limit the extraction operation when the state of the first steam is located in a third region defined by the limit curve. The turbine control device according to 2.   The restriction curve providing unit restricts the extraction operation during the low load operation of the extraction steam turbine in which the extraction steam turbine is operated by reducing the flow rate of the first steam based on the state of the steam. The turbine control device according to claim 1, wherein the turbine control device provides a limiting curve.   The controller may reduce the temperature of the first steam so that the state of the first steam returns to the first area when the state of the first steam enters the second area. The turbine control device according to claim 2, wherein the flow rate of the first steam is increased. A detector that detects a change rate or a change amount of the temperature of the first steam;
The control unit may return the state of the first steam to the first region when the rate of change or the amount of change is predicted to enter the state of the first steam within the second region. The turbine control device according to claim 2, wherein the temperature of the first steam is decreased or the flow rate of the first steam is increased.   The said control part outputs the warning about the said extraction steam turbine, when the temperature of the said 4th steam downstream of the said 2nd valve exceeds the limit temperature of one of the said turbines. Turbine control device. At least one turbine driven by steam;
A generator driven by the turbine;
A first valve for controlling the first steam before being introduced into the turbine;
A second valve for extracting a part of the second steam introduced into the turbine as a third steam and further using another part of the second steam as a fourth steam in the turbine;
A turbine control method for controlling a bleed steam turbine comprising:
The state of the first steam is expressed using the temperature and flow rate of the first steam as variables, and at least one restriction for restricting the extraction operation of the extraction steam turbine based on the state of the first steam Curve, provided by the limit curve provider,
When the state of the first steam is located in the first region defined by the limit curve, the second valve is controlled by the control unit so as to execute the extraction operation.
A turbine control method. At least one turbine driven by steam;
A generator driven by the turbine;
A first valve for controlling the first steam before being introduced into the turbine;
A second valve for extracting a part of the second steam introduced into the turbine as a third steam and further using another part of the second steam as a fourth steam in the turbine;
An extraction steam turbine comprising:
The state of the first steam is expressed using the temperature and flow rate of the first steam as variables, and at least one restriction for restricting the extraction operation of the extraction steam turbine based on the state of the first steam A curve, a limiting curve providing unit that provides a curve,
A controller that controls the second valve so as to execute the extraction operation when the state of the first steam is located in a first region defined by the limit curve;
A bleed steam turbine further comprising:

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