JPH055404A - Steam controlling method for steam using plant and device therefor - Google Patents

Abstract

PURPOSE:To effectively control steam header pressure and introduced steam flow rate without wastefully consuming steam. CONSTITUTION:This method includes a fundamental steam control process for controlling a turbine flow rate adjusting valve 4 so as to have a quantity of steam introduced from a ready-made plant A set to a steam flow rate set value on the basis of the appropriate pressure set value and practical pressure information of a steam header 1, after the set value of the pressure of the steam header 1 is changed in response to flow rate control information based on the actual quantity of steam introduced from the ready-made plant A the set value of steam flow rate. This method includes also a steam pressure lower limit regulating process for controlling the turbine flow rate adjusting valve 4 so that the pressure in the steam header 1 can not drop beyond the allowable lower limit of the pressure set value and a steam pressure upper limit regulating process for exhausting the steam staying inside the steam heaer 1 so that the pressure in the steam heaer 1 can not rise beyond the allowable upper limit of the pressure set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam control method and apparatus for a steam use process having a steam header connected to an existing plant, and more particularly to various steam use equipment including steam from a steam header and a steam turbine. The present invention relates to an improved steam control method and apparatus effective in a steam use process to be supplied to

[0002]

2. Description of the Related Art A conventional steam-using plant B is shown in FIG. 6, for example. This has a steam header 101 connected to an existing plant A via a connecting valve 109.
While the steam turbine 102 and other various steam-using devices 103 are connected to each other, steam introduced from the existing plant A is detected by the flow rate detector 104, and this analog detection signal is sent to the electronic cabana 105, and The opening degree of the cabana valve 106 is controlled based on the valve opening signal from the electronic cabana 105, and the flow rate of the introduced steam from the existing plant A is adjusted to be constant. A generator 108 is connected to the steam turbine 102 via a gear 107.

In this case, the electronic governor 105 described above is used.
Is an A / D converter 111 that converts an analog detection signal from the flow rate detector 104 into an actual flow rate signal that is a digital signal, and an introduced steam flow rate based on a flow rate set value increase / decrease signal from an external operation panel 112. A controller (CT) that sets a valve opening signal of the governor valve 106 based on a deviation between an actual flow signal from the flow detector 104 and a flow set value from the flow setter 113, and a flow setter 113 that sets a set value. 114 and a D / A converter 115 for converting the valve opening signal from the controller 114 into an analog signal.

Further, the pressure of the steam header 101 is usually maintained substantially constant because it is connected to the existing plant A, but depending on the operating condition of the plant B, other steam using the steam header 101 is used. The steam consumption of the device 103 changes, resulting in a steam excess or shortage condition, and as a result, the steam header 101 pressure increases or decreases. Therefore, in the prior art, for example, while connecting the low-pressure steam header 121 having a lower pressure than the steam header 101 and the steam header 101 in communication with each other, the let-down valve 122 is interposed in the communication portion between both headers,
The pressure of the steam header 101 is detected by the pressure detector 123, and based on the deviation between the actual pressure signal from the pressure detector 123 and the pressure set value rising / falling signal (pressure setting signal) from the external operation panel 124. The controller 125 is operated to set the valve opening signal of the letdown valve 122,
It is conceivable that the pressure of the steam header 101 is kept constant.

[0005]

By the way, in such a conventional steam-using plant, the amount of introduced steam is controlled by the cabana valve 106, and the pressure of the steam header 101 is controlled by the let-down valve 122. For example, when the pressure set value of the let-down valve 122 to be sent to the controller 125 is set low, the let-down valve 1
The valve opening degree of 22 has a tendency as shown in FIG. 7A, and the steam is let down even during the normal operation, so that the technical problem of wasting the steam wastefully occurs. Conversely, the controller 125 of the letdown valve 122
When the pressure set value to be sent to is set high, the valve opening of the letdown valve 122 has a tendency as shown in FIG.
Even if the pressure of the steam header 101 is lowered, the letdown valve 122 is already in the fully closed state, and the technical problem that the pressure of the steam header 101 cannot be controlled has been found.

[0006]

The present invention has been made to solve the above technical problems, and efficiently controls the steam header pressure and the introduced steam flow rate without wasting steam. The present invention provides a steam control method and apparatus for a steam-using plant that can be used.

That is, the steam control method for a steam-using plant according to the present invention has a steam header 1 connected to an existing plant A, as shown in FIG. 1, and from this steam header 1 to a steam turbine 2 and other Assuming a steam-using plant B that supplies steam to various devices 3 to be used, the pressure of the steam header 1 pressure corresponding to the actual steam introduction amount from the existing plant A and the flow control information based on the steam flow set value. After changing the set value, for adjusting the steam introduction amount to the steam turbine 1 so that the steam introduction amount from the existing plant A becomes the steam flow rate set value based on the pressure setting value and the actual steam header 1 pressure information. The basic steam control process for controlling the turbine flow rate adjusting valve 4 of the Under the condition that the steam header 1 pressure does not fall below the allowable lower limit value of the pressure set value under the condition that the steam header 1 pressure is lower than the lower limit value, the steam pressure lower limit regulation process and the steam header 1 pressure are set to the pressure set value. The steam pressure upper limit regulating step for discharging the steam in the steam header 1 so that the steam header 1 pressure does not exceed the allowable upper limit of the pressure set value under the condition of exceeding the upper limit of To do.

An apparatus invention embodying such a method invention has a steam header 1 connected to an existing plant A, as shown in FIG.
Assuming that the steam-using plant B is configured to supply steam to the steam turbine 2 and other various equipment 3 to be used, the amount of steam introduced into the steam turbine 2 is adjusted by being interposed between the steam header 1 and the steam turbine 2. A turbine flow rate adjusting valve 4, and a steam discharge adjusting valve 5 for adjusting the amount of steam discharged from the steam header 1.
Steam flow rate detection means 6 for detecting the actual steam introduction amount from the existing plant A, steam flow rate setting means 7 for setting the steam introduction amount from the existing plant A, and steam pressure detection for detecting the actual steam header 1 pressure. Means 8, steam pressure setting means 9 for setting the steam header 1 pressure, steam lower limit pressure setting means 10 for setting the allowable lower limit value of the pressure setting value of the steam header 1 pressure, and pressure setting value of the steam header 1 pressure The steam upper limit pressure setting means 11 for setting the allowable upper limit value and the flow rate control information based on the information from the steam flow rate detecting means 6 and the steam flow rate setting means 7 are converted into pressure control information, and steam is converted according to the pressure control information. Set pressure changing means 12 for changing the pressure set value of the pressure setting means 9, and this set pressure changing means 1
2 and the first turbine valve control means for controlling the opening degree of the turbine flow rate adjusting valve 4 based on the information from the steam pressure detecting means 8 so that the steam introduction amount from the existing plant A becomes the steam flow rate set value. 13, and when the steam header 1 pressure falls below the allowable lower limit of the pressure set value, the opening of the steam turbine flow control valve 4 is controlled so that the steam header pressure 1 does not fall below the lower limit of the pressure set value. The second turbine valve control means 14 and the steam discharge adjusting valve 5 so that the steam header 1 pressure does not exceed the allowable upper limit value of the pressure set value when the steam header 1 pressure exceeds the allowable upper limit value of the pressure set value. And a steam discharge valve control means 15 for controlling the opening degree of the.

In such a technical means, the steam discharge adjusting valve 5 may be appropriately selected as long as it can adjust the steam pressure of the steam header 1, but an atmospheric discharge valve or the like may be appropriately selected, but the discharge steam is effective. From the viewpoint of utilizing the above, it is preferable to use a let-down valve provided in a connecting pipe between the steam header 1 and another steam header having a lower pressure than the steam header 1.

As the set pressure changing means 12, when the flow rate control information (flow rate deviation) based on the information from the steam flow rate detecting means 6 and the steam flow rate setting means 7 indicates a flow rate increase, the steam pressure is lowered, When the flow rate control information (flow rate deviation) indicates a decrease in flow rate, if the steam pressure is to be increased, it may be changed continuously, or a dead zone may be provided in the middle to change the pressure discontinuously. The design can be changed as appropriate.

Further, the first turbine valve control means 1
3, the second turbine valve control means 14 and the steam discharge valve control means 15 are proportional if the opening degree of the control target valve is controlled so as to eliminate the pressure deviation based on the respective pressure deviations. It is possible to appropriately select a combination of integral and differential operations.

[0012]

The operation of the above-described technical means will be described by taking the steam control device as an example. In FIG. 1, when the steam flow rate detecting means 6 detects the actual amount of steam introduced from the existing plant A, the set pressure changing means 12 outputs flow rate control information based on the information from the steam flow rate detecting means 6 and the steam flow rate setting means 7. It is converted into pressure control information, and the pressure set value of the steam pressure setting means 9 is changed according to this pressure control information. Then, the first turbine valve control means 13 uses the information from the set pressure changing means 12 and the steam pressure detecting means 8 so that the amount of steam introduced from the existing plant A becomes the steam flow set value. The opening degree of the adjusting valve 4 is controlled.

The second turbine valve control means 14
Means that the steam header 1 pressure is the steam lower limit pressure setting means 1
When the pressure set value set at 0 becomes less than the allowable lower limit value, the opening degree of the steam turbine flow rate adjusting valve 4 is controlled so that the steam header pressure 1 does not become less than the lower limit value of the pressure set value.

Further, the steam discharge valve control means 15
The steam header 1 pressure is the steam upper limit pressure setting means 1
When the allowable upper limit value of the pressure set value set in 1 is exceeded, the opening degree of the steam discharge adjusting valve 5 is controlled so that the steam header 1 pressure does not exceed the allowable upper limit value of the pressure set value.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. FIG. 2 shows an embodiment of a steam control device of a steam using plant to which the present invention is applied. In the figure, the basic configuration of the steam-using plant B has a steam header 21 connected to the existing plant A via a connecting valve 22, and the steam header 2
1, a steam turbine 23 and various other steam-using equipment 24 are connected in communication with each other, and a cabana valve 25 is interposed between the steam header 21 and the steam turbine 23, while a low-pressure steam having a pressure lower than that of the steam header 21. The header 26 and the steam header 21 are connected for communication, and the let-down valve 2 is provided between the headers 21 and 26.
7 is interposed. A generator 29 is connected to the steam turbine 22 via a gear 28, and the rotation speed of the steam turbine 22 is governed by the synchronous frequency of the generator 29.

In this embodiment, reference numeral 31 is a flow rate detector (for example, orifice flow meter) for detecting the amount of steam introduced from the existing plant A, and 32 is the existing plant A.
External operation panel for setting the amount of steam introduced (flow rate setting value rise / fall signal: flow rate setting signal), 33 corresponds to deviation of actual flow rate signal from flow rate detector 31 and flow rate setting signal from external operation panel 32 Flow control signal (analog signal)
A flow rate controller [displayed by CT in the drawing] (in this embodiment, a PID operation [control operation consisting of proportional + integral + derivative operation] is used), 34 is a steam header 21
It is a pressure detector that detects pressure.

Reference numeral 40 is an electronic governor for controlling the opening degree of the governor valve 25, which uses the flow rate control signal from the flow rate controller 33 and the actual pressure signal from the pressure detector 34 as input signals. In this embodiment, the flow rate control signal from the flow rate controller 33 is adapted to be converted into a digital signal by the A / D converter 41. For example, the flow rate control signal is 4 to 20 mA.
Is converted into the number of pulses of a digital signal per unit time corresponding to the analog signal of. In this case, when it is necessary to supply steam from the plant B to the plant A, the setting of the flow rate controller 33 is changed and the introduction amount is 0 at the middle of the flow rate control signal, for example, the flow rate control signal. 1 when analog signal is 4 to 20 mA
It is also possible to set the steam to be supplied from the plant B to the plant A when 2 mA is 0.12 mA or less, and to supply the steam to the plant B from the plant A when 12 mA or more.

In the electronic governor 40, reference numeral 42 is a variable setting device for converting the digital flow rate control signal into a pressure set value signal with the characteristic shown in FIG. 3, for example, and the digital flow rate control signal has a predetermined level. When the flow control signal is increased (+), the number of pulses of the pressure set value decrease signal (-) of the corresponding level is increased, while when the digital flow control signal is decreased with respect to the predetermined level of the flow control signal ( The number of pulses of the pressure set value increase signal (+) of the corresponding level is increased in (-). Further, in this embodiment, the pressure set value signal of the variable setter 42 is also changed and set based on the pressure set value rising / falling signal from the external operation panel 44. still,
As a characteristic of the variable setting device 42, a dead zone m as shown by a dotted line in FIG. 3 may be set so that it does not respond to a slight change in the flow rate control signal.

Reference numeral 45 is a low value setter for setting an allowable lower limit value (lower limit pressure setting signal) of the pressure set value of the steam header 21 pressure, which can be set to an arbitrary value by the external operation panel 44. Is becoming Reference numeral 46 is a signal selector for selecting the larger one of the pressure setting signal from the variable setting device 42 and the lower limit pressure setting signal from the low value setting device 45.

Further, reference numeral 47 is an A / D converter for converting the actual pressure signal from the pressure detector 34 into a digital signal, and 48.
Is a valve controller that generates a valve opening signal of the governor valve 25 based on the deviation between the actual pressure signal from the pressure detector 34 and the signal from the signal selector 46 with the characteristics shown in FIG. In this embodiment, a PID operation type is used), and 49 is a D / A converter for converting the valve opening signal from the valve controller 48 into an analog signal.

Further, reference numeral 51 is an external operation panel for setting an allowable upper limit value (upper limit pressure setting signal) of the pressure set value of the steam header 21, and 52 is a pressure detector 34 from the pressure detector 34 having the characteristic shown in FIG. 5 (a). Letdown valve 27 based on the deviation between the actual pressure signal and the upper limit pressure setting signal P _max from the external operation panel 51.
Valve controller that generates the valve opening signal of
Is displayed] (in this embodiment, a PID operation type is used). As a result, the let-down valve 27 is opened only when the actual pressure signal from the pressure detector 34 exceeds the upper limit pressure setting signal P _max. (See FIG. 5 (b)). More specifically, as shown in FIG. 5A, if the PID result of the pressure deviation is (+), the let-down valve opening is in the direction of opening, and the PID result of the pressure deviation is (-). For example, if the actual pressure signal exceeds the upper limit pressure setting signal P _max as a result of the let down valve opening progressing in the closing direction, the let down valve 27 opens and continues to open until the PID result of the pressure deviation becomes 0, If the pressure deviation is 0 as it is, this opening is maintained, and the let-down valve 27 starts to close only when the PID result of the pressure deviation becomes (-).

Next, the operation of the steam controller of the steam-using plant according to this embodiment will be described. ◎ When the steam header pressure is stable (within the allowable pressure range) If the flow rate setting signal is set lower than the actual flow rate signal,
The flow rate control signal from the flow rate controller 33 becomes a flow rate decrease signal (-) of a predetermined level, the variable setter 42 increases the number of pulses of the pressure set value increase signal (+), and the current pressure set value becomes the above pressure set value. A pressure setting signal added by the number of pulses of the rising signal (+) is output (see FIG. 3). Therefore, the valve controller 48 shifts the valve opening signal to a direction closer than it is now (see FIG. 4), and the opening of the cabana valve 25 is closed, and the amount of steam introduced from the existing plant A is correspondingly increased. It decreases and converges with the set value corresponding to the flow rate setting signal as the target value.

When the flow rate setting signal is set to be larger than the actual flow rate signal, the flow rate control signal from the flow rate controller 33 becomes a flow rate increase signal (+) of a predetermined level, and the variable setter 42 causes the pressure set value decrease signal (-). Increase the number of pulses of
The pressure setting signal reduced by the number of pulses of the pressure setting value falling signal (-) is output to the current pressure setting value (Fig. 3).
reference). For this reason, the valve controller 48 shifts the valve opening signal in the opening direction more than the present (see FIG. 4), and the opening degree of the cabana valve 25 is opened, and the steam introduction amount from the existing plant A is correspondingly increased. It increases and converges with the set value corresponding to the flow rate setting signal as the target value.

◎ When the steam header pressure decreases (less than the allowable lower limit value), the steam consumption in the plant B using steam increases,
When the pressure of the steam header 21 decreases and falls below the allowable lower limit value, the valve controller 48 causes the pressure detector 34 to operate.
Generates a valve opening signal based on the deviation between the actual pressure signal from the lower limit pressure setting signal of the low value setting device 45 (see FIG. 4),
The opening degree of the cabana valve 25 is adjusted so that the pressure of the steam header 21 does not fall below the lower limit pressure setting value.

◎ When the steam header pressure increases (exceeds the allowable upper limit value), the steam consumption in the plant B using steam decreases.
When the steam header 21 pressure increases and exceeds the allowable upper limit value, the valve controller 52 causes the valve opening signal based on the deviation between the actual pressure signal from the pressure detector 34 and the upper limit pressure setting signal of the external operation panel 51. Is generated (see FIG. 5A), and the opening degree of the let-down valve 27 is adjusted so that the pressure of the steam header 21 does not exceed the upper limit pressure setting value (FIG. 5).
(See (b)).

[0026]

As described above, according to the inventions of claims 1 and 2, it is possible to control the steam header pressure within a certain settable range, and moreover, the allowable upper limit of the pressure set value of the steam header pressure. The steam in the steam header is discharged only when the value exceeds the value, and the amount of steam introduced from the existing plant can be controlled as long as it does not reach the allowable lower limit of the pressure setting value of the steam header pressure. The steam header pressure and the introduced steam flow rate can be efficiently controlled without consumption.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a steam control method for a steam-using plant and its apparatus according to the present invention.

FIG. 2 is an explanatory view showing an embodiment of a steam control device of a steam using plant to which the present invention is applied.

FIG. 3 is a graph showing the characteristics of the variable setting device 42.

FIG. 4 is a graph showing the characteristics of the valve controller 48.

5A is a graph showing a characteristic of the valve controller 52, and FIG. 5B is a graph showing a let-down valve opening characteristic by the valve controller 52.

FIG. 6 is an explanatory diagram showing an example of a conventional steam control device for a steam-using plant.

FIG. 7 is a graph showing a letdown valve opening degree characteristic by a conventional controller 125.

[Explanation of symbols]

A ... Existing plant, B ... Steam use plant, 1 ... Steam header, 2 ... Steam turbine, 3 ... Other steam use equipment, 4 ... Turbine flow control valve, 5 ... Steam discharge control valve, 6 ... Steam flow detection means, 7 ... Steam flow rate setting means, 8 ... Steam pressure detecting means, 9 ... Steam pressure setting means, 10 ... Steam lower limit pressure setting means,
11 ... Steam upper limit pressure setting means, 12 ... Set pressure changing means, 13 ... First turbine valve control means, 14 ... Second turbine valve control means, 15 ... Steam discharge valve control means

Claims (1)

What is claimed is: 1. A steam header (1) connected to an existing plant (A). From this steam header (1) to a steam turbine (2) and other various used equipment (3). In the steam-using plant (B) that supplies the steam, the pressure of the steam header (1) pressure corresponding to the actual steam introduction amount from the existing plant (A) and the flow rate control information based on the steam flow rate set value. After changing the set value, based on the pressure set value and the actual steam header (1) pressure information, the steam introduction amount from the existing plant (A) is adjusted to the steam flow rate set value to the steam turbine (1). Of the steam basic control process for controlling the turbine flow rate adjustment valve (4) for adjusting the steam introduction amount of the steam header (1) pressure below the allowable lower limit of the pressure set value Under a certain condition, the steam header (1) pressure is controlled so that the steam header (1) pressure does not fall below the allowable lower limit value of the pressure setting value, and the steam pressure lower limit regulation process that controls the turbine flow control valve (4). Under the condition that the allowable upper limit value of the set value is exceeded, the steam pressure upper limit regulating process of discharging the steam in the steam header (1) so that the pressure of the steam header (1) does not exceed the allowable upper limit value of the pressure set value. A steam control method for a steam-using plant, which is characterized by being provided. 2. A steam header (1) connected to an existing plant (A) for supplying steam from the steam header (1) to a steam turbine (2) and various other equipment (3) to be used. In the steam using plant (B), the turbine flow rate adjusting valve (4) is interposed between the steam header (1) and the steam turbine (2) to adjust the amount of steam introduced into the steam turbine (2),
A steam discharge adjusting valve (5) for controlling the steam discharge amount from the steam header (1) and an existing plant (A)
Steam flow detection means (6) for detecting the actual steam introduction amount from the plant, steam flow setting means (7) for setting the steam introduction amount from the existing plant (A), and the actual steam header (1) pressure. Steam pressure detecting means (8) for detecting, steam pressure setting means (9) for setting the steam header (1) pressure, and steam lower limit pressure setting for setting an allowable lower limit value of the pressure setting value of the steam header (1) pressure Means (10) and steam upper limit pressure setting means (1) for setting an allowable upper limit of the pressure set value of the steam header (1) pressure
1) and the flow rate control information based on the information from the steam flow rate detecting means (6) and the steam flow rate setting means (7) are converted into pressure control information, and the steam pressure setting means (9) is converted according to the pressure control information. Setting pressure changing means (12) for changing the pressure setting value of the
2) and based on the information from the steam pressure detecting means (8), the opening of the turbine flow control valve (4) is controlled so that the steam introduction amount from the existing plant (A) becomes the steam flow set value. The first turbine valve control means (13) and the steam header (1) so that the steam header pressure (1) does not fall below the lower limit value of the pressure set value when the pressure falls below the allowable lower limit value of the pressure set value. Second turbine valve control means (14) for controlling the opening of the steam turbine flow rate adjusting valve (4), and when the steam header (1) pressure exceeds the allowable upper limit of the pressure set value, the steam header ( 1) A steam discharge valve control means (15) for controlling the opening of the steam discharge flow rate adjusting valve (5) so that the pressure does not exceed the upper limit of the pressure set value. Steam control system of the over-time use plant.