JPS6275005A - Turbine steam valve warm-up device - Google Patents

Abstract

PURPOSE:To shorten the starting time without exceeding the thermal stress limit by controlling both closing period and closing width of a steam inlet valve in correspondence to both warm-up steam condition and valve condition. CONSTITUTION:In warming up a governor valve 3, a governor valve seat drain valve 5 is opened, and the governor valve 3 is closed. At the same time, a steam stop valve 2 is put under the opening and closing control. In the device for controlling the valve 2, the temperature difference DELTAT between the temperature at the outer surface and that at the inner surface of the governor valve 3 in addition to a main steam temperature TS are detected, and both are input into an inferring device 11, in which a target value 'r' for the governor valve inner surface temperature change rate is calculated. In addition, by using the inferring device 12, variations (DELTAa and DELTAb) in pulse-period 'a' and pulse-width 'b' are calculated, based on deviation 'e' between the target value 'r' and actual temperature changing rate 'y' at the inner surface of the governor valve 3 in addition to the maximum valve of 'y', or 'ym', measured after each pulse is generated by a closing-pulse generator 13. Finally, the valve-closing-pulse generator 13 generates valve opening command 'z', based on both signal 'a' and 'b'.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention aims to warm up the steam valve of a turbine in the shortest possible time while managing the valve metal thermal stress within an allowable value. The present invention relates to a turbine steam valve warm-up control device that controls the amount of inflow steam accordingly.

[Technical background of the invention and its problems] Generally, when warming up a turbine steam valve, the drain in front of the steam valve seat is opened, and the amount of inflow steam is controlled by opening and closing the upstream inflow control valve. This is done while controlling the temperature rise rate of the valve metal and the temperature difference between the inner and outer surfaces of the valve.

FIG. 3 is a turbine steam system diagram for explaining the warming up of the turbine steam valve. This is an example of warming up. 5 is a control valve seat drain valve. When warming up the regulator, the seat drain valve 5 is normally opened, the regulator valve 3 is closed, and the steam stop valve 2 is opened and closed to control the rate of change in temperature inside the regulator.

By the way, if this is done manually, for example, if the valve is started when it is completely cold, it will take a long time and will place a heavy burden on the operator.

Therefore, in recent years, turbine steam valve warm-up control has been performed using computers.

FIG. 4 is a diagram showing the state of control at this time, in which the computer outputs a signal to drive the steam stop valve 2 at a preset period a and pulse width. At this time, the rate of change y of the inner temperature of the regulating valve is not constant, but fluctuates around the target value r of the rate of change of the inner temperature of the regulating valve as shown in the figure.

In this way, in the conventional turbine steam valve warm-up control device,
Since the upstream valve opens and closes according to a predetermined period and pulse width,
No adaptability at all. In other words, because the upstream valve is opened and closed at a constant cycle and pulse width without considering the valve inner temperature difference or steam temperature, there are times when there is a lack of incoming steam and the warm-up time becomes unnecessarily long, and other times when had the problem that excessive thermal stress was applied to the valve metal due to excessive steam inflow.

[Object of the Invention] An object of the present invention is to provide a turbine steam valve warm-up control device that can always perform warm-up at the maximum allowable thermal stress limit and shorten the average startup time without shortening the valve life. With the goal.

[Summary of the Invention] Therefore, the present invention aims to heat up the metal in a short time without applying excessive thermal stress to the metal under those conditions by observing the temperature difference between the inside and outside surfaces of the steam valve and the rate of change in the inside temperature. When controlling the amount of steam inflow, the width and interval of the steam inflow pulses are determined based on predetermined principles so that the steam flow is completed.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example the case where the control valve 3 shown in FIG. 3 is warmed up.

FIG. 1 shows a main part configuration diagram of a turbine steam valve warm-up control system according to an embodiment of the present invention, in which reference numerals 11 and 12 are inference devices, and 13 is a valve opening/closing pulse generator.

The reasoner 11 calculates the input regulating valve inner surface temperature change rate target value r of the valve inner surface temperature change rate. The reasoner 12 calculates changes Δa and Δb in the pulse period a and the pulse width S from the deviation e between r and the actual rate of change of temperature inside the control valve y and the maximum value yII+ of y after each pulse.

The valve opening/closing pulse generator 13 generates a valve opening command Z from a and b.
generate.

That is, in the reasoner 11, "If 6 guns is large, then r is small."

The following control law R+jle says "If 8T is small, r is large"
l-1.

Achieve 1-2.

Ru1el-1: rΔd is large” → “r is small” R
u1el-2: rΔT is small" → "r is large" Similarly, the reasoner 12 realizes Ru1e 2-1-2-6 below.

Ru1e2 1: “re is positive” → “Δa is positive” R
u1e 2-2: "re is zero" → "Δa is zero" Ru1e 2-3: "re is negative" → "Δa is negative" Ru1e 2-4: rym is large" → "Δb is negative" Ru1e 2-5: ry+u is medium” → “Δ
b is zero” △a by the above algorithm of the reasoner 12
, Δb will be explained in detail with reference to FIG.

This means that parameters such as e+ym+Δa, Δb are “positive”
.

Since expressions such as "negative", "large", "medium", "small", and "zero" are abstract and have ambiguity, the measure distribution μij (i =
1 to 6 degrees (j=1 to 4).

In FIG. 2, μm1 corresponds to Ru1e, with the parameters 01 μm2, ym, μm3, Δa, and μ14, Δb (i=1 being Ru1e 2-1.i
=2 is Ru1e2-2, i=3 is Ru1e2-3, i=
4 is Ru1e2-4, i=5 is Ru1e2-5, i=6
is the Ru1e 2-6) measure distribution.

That is, regarding Ru1e2-1 in FIG. 2, in order to calculate the measure μm1° from the deviation e at this time, a measure distribution μm1 of the illustrated pattern is provided so that the deviation e is converted from −1 to +1. The pattern at this time was determined based on the empirical rules of experienced operators, and was further modified to create an optimal pattern. Since ym is irrelevant in this Ru1e, the measure μm2 regardless of yn+
° is 1. Since Δa is the same as in the case of e, in order to obtain the measure μI3° from Δa at that time, a measure distribution μm3 having the same pattern as e is provided. Δb is also irrelevant in this Ru1e, and no pattern is provided.

Hereafter, Ru1. e2-2~Ru1e2-
The measure distribution for erymrΔa and Δb in 6 is also set in advance as shown in the figure.

Now, when the values e 1 and ym I of each parameter are actually input as shown in the figure, the inference unit 12 calculates μ1j (i
-1 to 6. Measure μij' corresponding to the value input from the measure distribution of j= ] ~ 4) (i = = 1 ~ 6. l = 1 ~ 4)
Determine. Also, from the input parameter values, each R
In order to find the certainty of u1e's conclusion, μy I N
(i) is calculated using the following equation as a logical product of each measure μiJ0.

For example, if we look at Ru1e2-6, /jMIN(
6), the measure of Δb is μ62° (
The value μ64° corresponds to 〈μ61°), and the probability μ64°(△b) of the conclusion that “△b is positive” is
This is the shaded portion below μ64° of the measure distribution μ64.

In this way, by cutting the values above μy+N(i) and retaking them as μi3° (△a) and μit° (Δb), the conclusion can be confirmed for each Ru1e corresponding to the given parameters. You can get a sense of belonging.

Finally, μi3° (△”) + p x of each Ru1e
As the logical sum of the measure distribution of 4°(△b), calculate △ao as the center of gravity of this measure distribution.

Find Δb0.

For example, when calculating Δa0, Ru1e2-1~R
μm3°(△a)-p3's in u1e2-3
Collect the shaded parts of the measure distribution μ13 to μ33 as °(△a), and overlap them as shown in the upper right corner of Figure 2. The shaded part obtained is μMAX(△a).
By finding this center of gravity, we can obtain Δa as shown in the figure.
Find 0. The same applies to Δb0.

The above is an explanation of the operation of the inference device 12, but the inference device 11 operates in the same way, and inputs the temperature difference ΔT between the inner and outer surfaces of the control valve and the main steam temperature Ts to calculate the target value r for the rate of change in temperature inside the control valve. becomes.

In this way, the reasoner 11.12 executes calculations for each cycle of the opening/closing operation of the steam stop valve 2, calculates ΔaO1Δb0, and calculates the pulse period a and pulse width of the opening command 2 shown in FIG. update. As a result, the steam stop valve 2 is automatically opened and closed according to the main steam temperature and the temperature difference between the inner and outer surfaces of the regulator valve, and the regulator valve 3 can be warmed up in a short time without exceeding the thermal stress limit. can be completed.

[Effects of the Invention] As described above, according to the present invention, when warming up the steam valve, the period and width of the steam inflow valve are changed depending on the incoming steam state and the valve state, so that the steam Automatic warm-up operation adapted to the state and valve metal condition is now possible, completing warm-up of the steam valve in a short time without exceeding thermal stress limits.
It becomes possible to shorten the average startup time of the turbine.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a warm-up adjustment section of an automatic regulating valve warm-up device that is an embodiment of the present invention, FIG. 2 is a pattern diagram showing the logic and measure distribution of the inference calculation section of FIG. 1, and FIG. 4 is a general turbine steam system diagram for explaining the warming up of the regulating valve, and FIG. 4 is a time chart of various signals for explaining the warming up of the regulating valve in FIG. 11.12... Reasoner, 13... Valve opening/closing pulse generator.

Claims (2)

[Claims] (1) In a turbine steam valve warm-up control device that warms up steam by flowing steam into the steam valve by intermittently controlling the opening and closing of a valve provided upstream of the steam valve, the steam flowing into the steam valve 1. A turbine steam valve warm-up control device comprising: a regulator that adjusts the opening/closing period and width of the valve provided on the upstream side according to the state of the valve metal and the state of the valve metal at that time. (2) In a turbine steam valve warm-up control device that warms up steam by flowing steam into the steam valve by intermittently controlling the opening and closing of a valve provided upstream of the steam valve, the steam temperature and the inner and outer surfaces of the steam valve are determined. a first reasoner that inputs the temperature difference and calculates a steam valve inner surface temperature change rate target value using a measure distribution based on a predetermined control law; and the steam valve inner surface temperature change rate target value. A measure distribution based on a control law that predetermines increment commands for the opening/closing cycle and width of the valve provided on the upstream side by inputting the deviation from the steam valve inner surface temperature change rate and the peak value of the steam valve inner surface temperature change rate. 1. A turbine steam valve warm-up control device comprising: a second inference device that performs calculations using .