JPS5918211A - Starting control method of steam turbine - Google Patents

Abstract

PURPOSE:To restrain the thermal stress within the range of specified value and obtain the minimum starting time by a method wherein a starting schedule is calculated, at the starting, according to a generator load when the generator load exceeds the specified value and the turbine rotor thermal stress exceeds the limited value. CONSTITUTION:At the starting of a steam turbine, a starting schedule calculating unit 3 stores a starting control command K from an operator and input signals P1-Pn of the electricity generating process required for the monitor control of the turbine via an input processing device 2 of a turbine starting control device 1. When a generator load exceeds the specified value, and a turbine rotor thermal stress exceeds limited value, also after passage of the specified time, said calculating unit 3 calculates the starting schedule according to the generator load. On the other hand, in case of other than said case, said calculating unit 3 calculates as usual the starting schedule as a function of a main steam temperature, a pressure and a turbine metal temperature, then starts the steam turbine via the starting control unit 4.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a steam turbine startup control method, and particularly to a steam turbine startup control method that obtains an optimal startup schedule for smooth startup of the turbine. Regarding the method.

[Technical background of the invention]

Generally, when starting a turbine, it is necessary to suppress the lifetime consumption that occurs during startup to within the planned value, so the change in turbine metal temperature during operation is estimated, and the rotor thermal stress that occurs due to this is reduced to the planned lifetime consumption. The time required for each startup stage (hereinafter referred to as a startup schedule) is predetermined as the recommended startup time so that it is within the corresponding value.

Normally, the main steam temperature is constant in a relatively high load area, so it is determined from the relationship between the generator load and the first stage Yamaguchi steam temperature. Because the main steam temperature and turbine metal temperature change in a complicated manner depending on the conditions, etc., we assume that the mismatch temperature during ventilation (1st stage Yamaguchi steam temperature and 1st stage case song temperature) is based on the temperature characteristics of standard boilers and turbines. It is determined from the relationship between the first stage inner metal temperature (temperature defined as the difference from the inner metal temperature) and the first stage inner metal temperature.

[Problems with the latest technology]

However, during actual operation, it is extremely unclear to distinguish between low-load areas and high-load areas from the time of ventilation, and especially when starting up after ventilation, such as during a mid-startup after turbine ventilation or restarting after a plant accident. When starting control, it is very ambiguous which startup schedule to use.
For example, the actual situation is that they are differentiated by one large vent in the startup process (for example, turbines in parallel). For this reason, depending on the timing, the system may be operated based on an unreasonable startup schedule, or conversely, it may be operated based on a startup schedule that is more gradual than necessary.

Particularly in recent years, with the increase in the number of nuclear power plants, many thermal power plants are being operated as medium-load power plants, resulting in an extremely large number of startups and shutdowns, resulting in rotor thermal stress. There is a strong desire for turbine start-up control that achieves a start-up schedule that keeps the cost within a value equivalent to the planned lifetime cost and minimizes the plant start-up time.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a steam turbine startup control command that can suppress the thermal stress of the turbine within a planned value and provide an optimal startup time. There is a particular thing.

[Summary of the invention]

In order to achieve the above object, the present invention calculates a startup schedule, which is the time required for each startup stage, as a function of the main steam temperature and pressure from the boiler and the turbine metal temperature just before venting the turbine, and starts the startup based on this. In the start control method for a steam turbine that performs control, if there is a start control command after turbine ventilation, the generator load and turbine rotor thermal stress are detected, and the generator load is greater than a specified value and the turbine rotor thermal stress is a limit value. If the specified time has passed, the startup schedule is calculated according to the generator load. Otherwise, the startup schedule is calculated as a function of the main steam temperature and pressure immediately before turbine ventilation and the turbine metal temperature. The feature is that the steam turbine is activated by

(Embodiments of the invention) An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 is a block diagram showing an example of a system configuration for turbine start-up control according to the present invention. In Fig. 1, reference numeral 1 denotes a turbine start-up control device, which provides input signals (Pl, P, . . . ) for the power generation process necessary for monitoring and controlling the turbine.
・.

Pn) and the startup control command from the operator are read into the input processing device 2. In addition, the startup schedule calculation unit 3 periodically calculates the input signal (p, I p! t
. . , Pn) and the activation control command K via the input processing device 2 to execute the operations described below. Further, when there is a startup control command K (K-1), the startup control section 4 outputs an operation signal S based on the startup schedule calculated by the startup schedule calculation section 3.

FIG. 2 shows the operation of the startup schedule calculation section 3 in a flowchart. In the figure, first, in step 10, it is determined whether this is the first pass after the turbine ventilation timing is established, and if YES, in step 11, the parameters required for calculating the startup schedule, main steam temperature (MST), main steam pressure ( MS P ), first stage inner surface metal temperature (TFSI), etc. are stored, and the process proceeds to step 12.

In step 12, the high pressure rotor thermal stress limit value (HPL) is determined as a condition for determining the startup schedule calculation type.
and intermediate pressure section rotor thermal stress limit value (IPL), first stage inner surface metal temperature [(TF8I) and reheat steam inner surface metal temperature (
TRBI) is calculated as a function.

Figure 3(a) shows this high pressure rotor thermal stress limit value (HP
L) and 1st stage inner surface) 9 Le1M If (TF8I
) is expressed as HPL-fa (TF8I), and in Figure 3 (bl is the intermediate pressure section rotor thermal stress limit value (
It shows the relationship between IPL) and c) thermal steam chamber inner surface metal temperature (TRBI), and is expressed as IPL-fb (TRBI).

On the other hand, if the determination result in step 10 is NO, steps 11 and 12 are bypassed and the process proceeds to step 13.

In step 13, it is determined whether or not there is a starting dividing section command K from the operator, and if No (K=Q), the operation is completed and the system waits until the next starting. If the judgment result in this step is YES (K-1), proceed to step 14, and use the generator load (GEN) and the thermal stress of the high-pressure and intermediate-pressure rotors to calculate the starting schedule. determine the type,
If the calculation type is 1, the process goes to step 15, and if the calculation type is 2, the process goes to step 16.

As a result of the determination in step 14, if calculation type 1 is selected, the process proceeds to step 15, where the main steam temperature during turbine ventilation stored in step 11 is determined.

(MST), main steam pressure (MAT), and first stage internal metal temperature (TF8I) to calculate a start-up schedule to complete the operation.

As a result of the determination in step 14, if calculation type 2 is selected, the process proceeds to step 16, where the startup schedule is calculated using the generator load (GEN) as a function, and the operation is completed.

Note that the items of the startup schedule that are calculated include the turbine speed increase rate, constant speed holding time, rated holding time, load increase rate, initial load holding time, etc.

On the other hand, FIG. 4 is a logic chart diagram showing the determination of calculation types 1 and 2 selected in step 14 above.
In the figure, calculation type 1 is selected as follows (1)
This is when any one of (4) to (4) is satisfied.

(11 When the generator load (GEN) is below the specified value (GL).

(2) High pressure part rotor thermal stress (HPa) limit value (HL)
L) or more.

(3) The intermediate pressure rotor thermal stress (IPa) is the limit value (I
PL) or more.

(4) The generator load (GEN) is above the specified value (GL), and the high pressure rotor thermal stress (HP a ) is the limit value (HP T,
) or less, and when the intermediate pressure section rotor swallow stress (IPm) is less than the limit value (I PL) and within the specified time (1).

Further, calculation type 2 is selected when the following (5) is satisfied.

(5) The generator load (GBN) is above the specified value (GL), the high pressure rotor thermal stress (HPa) is below the limit value (HPL), and the intermediate pressure rotor thermal stress (IPa) is below the limit value (I
PL) or less and the specified time (11 or more).

Next, the specified value (GL), limit value (HPL)/(IPL), and specified time (t) described in (1) to (5) above,
I will explain about it. First, the specified value (GL) is set to the first stage inner metal temperature (TFt8I), the reheat steam chamber inner metal temperature (TRBI), or a load range close to the rated value. The limit value (HPL) (IPL) is calculated in step 12 as a function of the first stage inner metal temperature (TF8I) during turbine ventilation or the reheat steam chamber inner metal temperature (TRBI). Further, the specified time (1) is a time during which thermal stress is stabilized, and is set to a value several times the delay time from a change in main steam temperature to a change in rotor volume temperature.

In addition, in the above embodiment, startup schedule calculation type 1
．． The generator load (GBN) is used as the condition for selecting 2, but instead of this, the main steam temperature (M8T), the 1st stage inner metal temperature (TF8I) t, or the reheat steam chamber inner metal temperature ( TRBI) etc. can also be used.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the steam turbine startup control method of the present invention, when the generator load is not above the specified value and the turbine rotor thermal stress is below the limit value and a specified period of time has elapsed, the generator is switched to the machine load. At other times, the startup schedule is calculated as a function of the main steam temperature and pressure during turbine ventilation and the first stage inner metal temperature, and startup auxiliaries are performed based on this. Therefore, it is possible to suppress the rotor thermal stress of the turbine generated during startup to within a value corresponding to the planned life consumption, and to obtain the shortest startup time most suitable for the condition of the turbine. In addition, the rotor thermal stress limit value used to determine the conditions for distinguishing startup schedule calculation types 1 and 2 is calculated as a function of the first stage inner metal temperature during ventilation or the reheat steam chamber inner metal temperature. Therefore, the optimal limit value can be obtained depending on the startup mode of the turbine.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the turbine start control device of the present invention, Fig. 2 is a flowchart showing the operation of the start schedule calculation section in Fig. 1, and Fig. 3 (8) shows high pressure section rotor heat. Figure 3 (h) is a diagram showing the relationship between the stress limit value and the inner metal temperature of the first stage, and Figure 4 (h) is a diagram showing the relationship between the intermediate pressure section rotor thermal stress limit value and the inner metal temperature of the reheat steam chamber. 2 is a logic chart diagram showing a method for selecting a calculation type of a startup schedule. FIG. DESCRIPTION OF SYMBOLS 1... Turbine start-up control device, 2... Input processing device, 3... Start-up schedule calculation part, 4... Start-up control part. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] (1) Immediately before turbine ventilation, a startup schedule, which is the time required for each startup stage, is determined as a function of the main steam temperature and pressure from the boiler and the turbine metal temperature, and the startup control of the steam turbine is performed based on this. In the start-up control method, when a start-up control command is issued after turbine ventilation, the generator load and turbine rotor thermal stress are detected, and the generator load and turbine rotor thermal stress exceed a specified value for a specified period of time. When the above period has elapsed, the startup schedule is calculated according to the generator load, and at other times, the startup schedule is calculated as a function of the main steam temperature and pressure immediately before turbine ventilation, and the turbine metal temperature, and the steam turbine is started. A method for controlling start-up of a steam turbine, characterized in that: (2) A method for starting a steam turbine according to claim (1), wherein the limit value of the turbine rotor thermal stress is calculated as a function of the turbine metal temperature immediately before turbine ventilation.