JPH06101420A - Control device for bleeder turbine - Google Patents

Abstract

PURPOSE:To obtain flexible operability and service by arranging a control device which forms a condition that influence of a signal for controlling a main steam control valve on an extraction control valve is suspended, and directly shifting to a bleed operation mode from a main steam pressure control mode of a turbine. CONSTITUTION:A bleeder turbine, being provided with an extraction control valve and a main steam control valve, takes in steam from a steam generator, drives a turbine, generates power, and supplies the steam to a processing system. In this case, a speed deviation signal expection circuit 50 is provided. Increase of an extraction governing valve opening command 43 due to three arms is suppressed by the expection circuit 50, and the extraction governing valve opening command 43 is decreased by an extraction control valve forcibly opening/closing signal 47. Namely, at the time when an extraction control valve opening command 46 is selected by a higher value selector 42 among the extraction control valve forcibly opening/closing signal 47, a stage pressure of the bleed air is increased to the value necessary to shift to bleed operation. Deviation is reduced from the pressure in the processing system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bleeding turbine of a cogeneration plant for the purpose of selling power and supplying steam, and more particularly to control of a bleeding turbine capable of shifting to bleeding motion in any control mode. Regarding the device.

[0002]

2. Description of the Related Art In a conventional industrial extraction turbine, the transition from the normal turbine operation mode to the extraction operation mode is limited to only when the turbine operation mode before the extraction operation transition is the governor control mode. ing. For the control method of this type of turbine, see “Thermal Power Generation” (196
(September and August) "Two-stage extraction condensate turbine electro-hydraulic governor" and "Thermal power generation" by Masaki Shimizu and Makoto Kishigami (19)
70, July) by Koichi Kawatake and Ryosuke Arie in a paper entitled "Application of Electro-Hydraulic Governor to Industrial Turbine".

[0003]

In the prior art, when the process in which the main steam pressure hardly changes when the normal turbine operation mode is changed to the extraction operation mode, the main steam pressure control is performed by the turbine. There is no problem because you do not have to. However, in the case of a plant having a process with unstable main steam pressure (such as a cogeneration plant), main steam pressure control by a turbine is necessary, and from this state of main steam pressure control, the extraction turbine is in its original form. It is necessary to shift to the bleeding motion (bleeding pressure control) mode. However, due to the original characteristics of the extraction turbine (three-arm characteristics), in the case of the main steam pressure control mode, the conditions necessary for shifting to extraction operation cannot be achieved, and therefore it cannot be changed to extraction operation. There was a problem. An object of the present invention is to provide a control device for an extraction turbine that can directly shift to an extraction operation mode in any control mode.

[0004]

The above-mentioned object is to temporarily hold a circuit of a speed deviation signal (a signal for controlling the main steam control valve) which influences the bleed control valve at a certain value, and to further hold the bleed control valve. It does not affect the. Under these conditions, the conditions necessary for shifting to the extraction operation, that is, the conditions for keeping the deviation between the stage pressure of the extraction part and the pressure required by the process system within a predetermined range, are directly It is achieved by performing a transition to extraction operation.

[0005]

The extraction control valve of the extraction turbine is located between the high pressure side and the low pressure side of the turbine, and controls the extraction pressure by controlling the amount of steam flowing to the low pressure side. Since the speed deviation signal influences the control of this bleeding control valve, the circuit of the speed deviation signal is temporarily held. In this hold state, the bleed air control valve forced opening / closing signal allows the opening degree of the bleed air control valve to be lowered to a position at which the bleed air operation can be shifted (the bleed air pressure is increased). In this way, the conditions for the transition to the extraction movement are satisfied, and the transition is possible.

[0006]

Embodiments of the present invention will be described with reference to the drawings. First, the outline of a plant to which the present invention is applied will be described with reference to FIG. In this plant, the gas turbine 1 and the generator 2 driven by the gas turbine 1 are each 3
Stand, steam generator 3 that uses the exhaust gas heat of the gas turbine 1
Is a cogeneration plant including three units (two units are not shown), an extraction turbine 23 (high pressure turbine 4, low pressure turbine 5) and a steam turbine generator 7 each. The main purpose of the extraction turbine 23 is to supply steam having a constant pressure to the process (steel plant, chemical plant, etc.) through the extraction line 8 (the extraction control valve 25 of the extraction turbine controls the pressure of the extraction line 8 to be constant). That is, the steam turbine generator 7 is driven to generate and sell power. The main steam amount input to the extraction turbine 23 is controlled by the main steam stop valve 26 and the main steam control valve 27. The steam generator 3 includes a high-pressure steam generator 9 that generates high-pressure steam and an intermediate-pressure steam generator 10 that generates medium-pressure steam. The steam generated from the high-pressure steam generator 9 is extracted by the extraction turbine 2 connected to the main steam line 11.
3 is supplied. The steam generated from the medium pressure steam generator 10 is supplied to the mixed combustion device 18 of the gas turbine 1 connected to the mixed combustion line 12. In this plant, as described above, there are two other equipment similar to the steam generator 3, and the respective high-pressure steams 13 and 14 are supplied to the extraction turbine 23 via the main steam line 11. Also, medium pressure steam 15, 1
Similarly, 6 is supplied to the co-firing device 18 of the gas turbine 1 via the co-firing line 12. Extraction bypass line 6
Is a line for supplying steam to the process through this line when the extraction turbine is stopped, and the pressure of the extraction line 8 is kept constant by the pressure regulating valve 15. The main steam bypass line 16 is a line that allows the main steam to escape to the condenser when the extraction turbine 23 trips, and is controlled by the main steam bypass valve 24. The steam of the mixed combustion line 12 is supplied to the mixed combustion device 18 of the gas turbine 1 as a steam injection of the gas turbine 1 through a flow control valve 17 (for NOX countermeasures). Further, since there are two other gas turbines 1 as well as the steam generator 3, the steam in the co-firing line 12 flows from the co-firing line 12 to each flow control valve 1.
It is supplied to the mixed burners 21 and 22 of each gas turbine through 9 and 20. The above is the overall configuration of this plant.

Next, a general control algorithm of the extraction turbine will be described with reference to FIG. FIG. 2 shows a control block diagram incorporated within the governor controller.
The extraction turbine must be controlled so that the extraction pressure remains constant even if the load or main steam pressure changes, and conversely, the load or main steam pressure remains constant even when the extraction pressure changes. It must be controlled to maintain it (main steam pressure control mode). In order to realize this, it is necessary to simultaneously control the main steam control valve 27 and the extraction control valve 25 described in FIG. Specifically, when the load is increased, the stage pressure of the turbine in the extraction portion (pressure in the extraction portion) is increased. Therefore, it is necessary to perform control to keep the stage pressure of the extraction portion constant. Actually, how much the extraction control valve 25 is opened with respect to a change in load depends on each individual turbine, and these causal relationships are called three-arm characteristics of the turbine. This three-arm characteristic is the gain K1 (3
6), K2 (37), K3 (38) and the upper and lower limits are determined by the configuration of the mitter 41. In FIG. 2, the speed deviation signal ΔS (35) is a governor position signal (GOV signal) 3 similar to a general turbine control algorithm.
1. The load limiter position signal (LLM signal) 32 and the main steam pressure deviation signal (MSP deviation signal) 33 are input to the low value selector (LVG) 34, and the low value selector (LVG) 3
It is output from 4. The speed deviation signal ΔS (35) is added to the extraction pressure deviation signal ΔP (4
0) is corrected, and the corrected signal becomes the main steam control valve opening command 39. On the other hand, the extraction pressure deviation signal ΔP (4
0) is the speed deviation signal ΔS due to the three-arm characteristic
The correction of (35) is performed, and the corrected signal becomes the extraction air control valve opening command 46 by the three arms. In addition, a PB (4) for forced opening and closing of the extraction control valve installed outside the control device
In 4), when the turbine is started, the bleed air control valve 25 is forcibly set to the fully open position, and the analog memory (AM) 45 provided in the control device is increased or decreased to output the bleed air control valve forced opening / closing signal. On the other hand, when generating 47, the extraction control valve 25 is gradually closed to increase the stage pressure of the extraction portion when shifting to extraction operation. The above is a general extraction turbine control algorithm.

Next, the problem of a general control algorithm of the extraction turbine will be described. In order to shift the normal turbine operation to the extraction operation, the extraction control valve open / close signal 47 is gradually decreased by the extraction control valve open / close PB (44), and the extraction control valve opening command 43 is decreased. As a result, the extraction control valve 25 gradually closes, and the stage pressure in the extraction section rises. When the bleed air control valve forced opening / closing signal 47 is decreased, the high price selector (HVG) 42 selects the bleed air control valve opening command 46 by three arms at a certain point. Therefore, no matter how much the bleed air control valve forced opening / closing signal 47 is decreased, the bleed air control valve 25 does not close any more, and the stage pressure in the bleed air portion does not rise. Here, in order to shift to the extraction operation, the deviation between the stage pressure of the extraction part and the pressure required by the process system must be within a predetermined range at this point.
On the other hand, when the extraction control valve 25 is gradually closed by the extraction control valve forced opening / closing PB (44) in the main steam pressure control mode state, the difference between the pressure in the vicinity of the main steam control valve 27 and the stage pressure in the extraction section is increased. Disappears. For this reason,
During this period, the main steam flow rate becomes difficult to flow, and as a result, the main steam pressure rises. Since the extraction steam turbine is in the main steam pressure control mode, the main steam control valve opening command 39 is increased to suppress the main steam pressure and the main steam control valve 27 is closed. This means that the speed deviation signal ΔS (35) increases. This increase is due to gain K2 (3
It is added to the extraction pressure deviation signal ΔP (40) via 7) and becomes the extraction air control valve opening command 46 by the three arms. That is, gradually closing the extraction control valve 25 means increasing the extraction control valve opening command 46 by the three arms. This indicates that the point at which the extraction control valve opening degree command 46 by the three arms is selected by the high value selector 42 is gradually increased. This means that the point at which the stage pressure of the bleed portion to be raised can be raised is lowered by reducing the bleed air control valve forced opening / closing signal 47. Therefore, the extraction control valve opening command 4
At the time point 6 is selected, the stage pressure of the extraction portion does not reach the pressure required to shift to extraction operation. Therefore, the stage pressure of the extraction portion, which is a condition for shifting to the extraction operation, and the pressure deviation required by the process system cannot be kept within a predetermined range, so that there is a problem that the extraction operation cannot be performed.

An embodiment of the present invention which solves the above problem will be described below with reference to FIG. The present embodiment is characterized in that the speed deviation signal exclusion circuit 50 is provided. The speed deviation signal exclusion circuit 50 sets the value of the speed deviation signal ΔS (35) to the initial value (the value of ΔS (35) before the change to the extraction operation mode) when the main steam pressure control mode is changed to the extraction operation mode. ) Is held and the influence from the speed deviation signal ΔS (35) is excluded until the extraction operation shiftable state is reached.
As a result, it is possible to suppress an increase in the bleed air control valve opening / closing command 46 by the three arms and further reduce the bleed air control valve opening / closing command 43 by the bleed air control valve forced opening / closing signal 47. That is, the stage pressure of the bleeding portion increases, and when the bleeding control valve opening / closing command 46 by the three arm is selected by the high value selector 42 from the bleeding control valve forced opening / closing signal 47, the stage pressure of the bleeding portion is changed to the bleeding operation. Reach the pressure needed to make the transition. In this way, the deviation from the pressure required in the process system falls within the specified range,
It is possible to shift to extraction operation. The speed deviation signal excluding circuit 50 is, as a specific circuit, as shown in FIG. 1, a flip-flop (FF) 51 that catches the timing of starting the extraction operation transition, and a speed deviation signal ΔS (at the time of entering the extraction operation transition operation. 35) for storing the analog switch (ASW) 52 and a monitor relay (MR) 5 for catching that it is possible to shift to the extraction operation.
5 and Bump Restaurant Spha (BMP), which is provided so that the signal switches to bumpless when switching to control with normal three-arm characteristics after shifting to extraction operation.
53, and a knot (NOT) 54 for outputting a timing command for switching to bumpless.

Next, the operation of the speed deviation signal exclusion circuit 50 will be described with reference to FIGS. 1 and 3. In the main steam pressure operation mode before transition to the extraction operation, the extraction adjustment valve forced opening / closing signal 47 is selected as the extraction adjustment valve opening degree command 43, and the output signal 61 of the monitor relay (MR) 55 becomes “0”. ing.
Before the extraction operation transfer operation, the flip-flop (FF) 5
Since the output signal 56 of 1 is “0”, the analog switch (ASW) 52 receives the input NO. 2 signals are selected. The output signal 60 of the NOT 54 is "1".
Then, the bump restaurant spha (BMP) 53 selects the output signal 57, and the speed deviation signal exclusion circuit 50
Indicates a state in which control is performed by the normal three-arm characteristic described in FIG. In order to shift the bleed air control valve opening command 43 in order to shift to the bleed air operation, the Philip flop (FF) 51 is set by controlling the bleed air control valve forced opening / closing PB44 to be closed, and the output signal 5
6 is "1" (time t ₁ in FIG. 3), an analog switch (ASW) 52 is input NO. Select the signal 58 of 1
The speed deviation signal ΔS (35) is held (solid line from time t ₁ to time t _{2 in} FIG. 3). As a result, the influence (increase) of the speed deviation signal ΔS (35) can be excluded, and the stage pressure of the extraction portion can be raised to a pressure at which the extraction operation can be shifted by the extraction control valve open / close signal 47 (FIG. 3). Time t ₂ ). When such a state is illustrated, time t ₁ (63) to time t ₂ (6
4). The speed deviation signal ΔS
The (dotted line) shows the output in the non-hold state.
When the stage pressure of the bleeding portion rises to a pressure capable of bleeding operation, and the bleeding air control valve opening command 46 by the three arm is selected as the bleeding air control valve opening command 43, the output signal 61 of the monitor relay (MR) 55. Becomes "1", the flip-flop (FF) 51 is reset, the output signal 56 of the flip-flop (FF) 51 becomes "0", and the analog switch (ASW) 52 outputs the speed deviation signal 5
Select 7. On the other hand, the output signal 60 of the knot (NOT) 54 becomes "0", and the bump restaurant spreader (BM)
The P) 53 switches from the signal 58 to the signal 57 to bumpless at a certain constant rate so as to prevent the sudden change of the signal 59, and switches to the control by the normal three-arm characteristic. Such a state is represented as a BMP output after time t _{2 in} FIG. As described above, the speed deviation signal exclusion circuit 50 excludes the influence from the speed deviation signal ΔS (35) and requests the stage pressure of the extraction portion and the process system which are conditions for shifting to the extraction operation. In order to keep the deviation from the applied pressure within a predetermined range, the bleeding air control valve opening command 43 can be lowered.

As described above, in this embodiment, it is possible to directly shift from the main steam pressure mode to the extraction pressure control mode. Specifically, as in the control mode transition procedure 65 to 67 shown in FIG. 5, when transitioning to extraction operation while the turbine is operating in the main steam pressure control mode, it has been temporarily switched to the governor control mode until now. The control mode is shifted (step 65), and the extraction operation is shifted in the governor control state (step 66). Next, by switching the governor control to the main steam pressure control (procedure 67), a complicated operation of shifting to the main steam pressure control and the extraction pressure control mode was required. However, in the present embodiment, it is possible to directly shift from the main steam pressure mode to the extraction pressure control mode (shown in mode transition (procedure 69) in FIG. 5). Incidentally, when shifting to the main steam pressure control mode while the turbine is operating in the extraction operation mode, the procedure reverse to the above procedure is followed.

[0012]

According to the present invention, since it is possible to directly shift from an arbitrary control mode to the extraction operation, it is possible to achieve considerable flexibility in terms of operability and operation of the entire plant. Also, in a plant that frequently uses the main steam pressure control mode, it is possible to easily and quickly switch to the extraction pressure control mode, which can reduce operator's erroneous operation and burden, and In terms of aspects, it will provide a very user-friendly system.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and is a control block diagram of an extraction turbine provided with a speed deviation signal exclusion circuit for eliminating an influence from a speed deviation signal when switching extraction modes.

FIG. 2 shows a control block diagram of a general extraction turbine.

FIG. 3 is a time chart that temporally shows the relationship between the speed deviation signal and the extraction pressure in the extraction operation transition operation.

FIG. 4 shows the overall configuration of a cogeneration plant.

FIG. 5 shows a control mode transition procedure of the extraction turbine.

[Explanation of symbols]

23 Extraction Turbine 25 Extraction Control Valve 27 Main Steam Control Valve 50 Speed Deviation Signal Exclusion Circuit 51 Phillip Flop (FF) 52 Analog Switch (ASW) 52 and Can Be Moved to Extraction Operation 53 Bump Restaurant Spha (BMP) 54 Knot (NOT) 55 Monitor Relay (MR)

Claims (3)

[Claims] 1. A steam control valve comprising a bleeding control valve and a main steam control valve, and a steam generator for generating high-pressure steam and the steam from the steam generator are taken in to drive a turbine to generate electricity and generate steam. In the extraction turbine that supplies the process system (steel plant, chemical plant, etc.) via turby, the extraction control valve is not temporarily affected by the signal for controlling the main steam control valve (speed deviation signal) A control device for an extraction turbine, characterized in that it has a control means for forming the above, and directly shifts from a main steam pressure control mode of the turbine to an extraction operation mode. 2. The control means according to claim 1, wherein the control means detects the timing of the extraction operation transition, the means for storing the speed deviation signal at the time of entering the transition operation, and the fact that the transition is possible. A bleed turbine control device comprising: means, a means for switching the speed deviation signal to bumpless after the transition, and a means for outputting a timing of switching to bumpless. 3. The control means according to claim 1 or 2, wherein the control means comprises a circuit for temporarily holding the speed deviation signal when the turbine main steam pressure control mode is changed to the extraction operation mode. Control device for the extraction turbine.