JPH0655006U - Main steam temperature controller for steam superheater for boiler - Google Patents

Abstract

(57) [Summary] [Purpose] Which of the two is correct when the main steam temperature is monitored by two thermometers on the outlet side of the steam superheater and there is a deviation in the temperature values measured by both thermometers? To quickly determine. [Configuration] temperature t _a which is measured by two thermometers 9,10,
When a deviation occurs in t _b and the temperature deviation value Δt exceeds the allowable temperature deviation value Δt _O , the temperature value T _S measured by the inlet thermometer 8 of the steam superheater and the combustion supplied to the superheater Temperature deviation value Δ on the inlet side and outlet side of the superheater found from the gas combustion conditions
And a T _S seek main steam temperature estimate _{t C = T S + ΔT S} . The one whose estimated temperature value t _C is closer to the measured temperatures t _a and t _b is selected as the correct thermometer.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 In the present invention, two thermometers are arranged in the outlet main steam pipe of the steam superheater, one of which serves as the main steam control thermometer and the other of which serves as the backup thermometer to monitor the main steam temperature value. The present invention relates to a temperature control device for a steam superheater for a boiler.

[0002]

[Prior art]

 The steam for driving the steam turbine is usually superheated steam to enhance the turbine effect. If the temperature of the superheated steam is too low, drainage will occur inside the turbine and the turbine will be damaged. Controlling temperature is extremely important.

The steam superheater for obtaining superheated steam is composed of a combustion chamber 14 for obtaining high-temperature combustion gas as shown in FIG. 2 and a saturated superheater for heating saturated steam into superheated steam. It is mainly composed of two steam superheaters 2 and 3, a superheat desuperheater 4 for injecting pure water to obtain a predetermined steam temperature, and a flue 15 for discharging high temperature combustion gas. The two steam superheaters 2 and 3 are connected in series and installed in the flue 15. The saturated steam supplied from the steam drum 1 is supplied to the first steam superheater 2 via the steam pipe 16. After passing through the superheat desuperheater 4, it passes through the second steam superheater 3 to become superheated steam having a desired constant temperature (hereinafter referred to as main steam). Normally, saturated steam first passes through the first steam superheater 2 located downstream of the high temperature combustion gas flowing through the flue 15.

The steam temperature control of the steam superheater is generally a reduction measured using a thermometer 17 arranged in a steam pipe 16 connecting the outlet side of the first steam superheater 2 and the inlet side of the superheat reducer 4. There are two control systems, a steam temperature control system on the inlet side and a main steam temperature control system using a control thermometer 9 arranged on the main steam pipe 13 connected to the outlet side of the second steam superheater 3. Is going on. In addition to the control thermometer 9, the backup thermometer 10 constantly monitors the temperature of the main steam in the main steam pipe 13 to back up whether or not the control thermometer 9 normally measures the temperature. It is like this.

The reducer inlet side steam temperature control system adjusts the air-fuel ratio control system 18 so that the inlet side steam temperature of the overheat reducer 4 becomes a preset temperature according to the saturated steam flow rate. Further, the main steam temperature control system sets the outlet steam temperature of the superheat reducer 4 to the main steam temperature so that the main steam temperature of the final superheated steam on the outlet side of the second steam superheater 3 becomes a desired constant temperature. The amount of pure water supplied to the overheat reducer 4 is controlled using the water injection valve 5 so that the temperature is determined by the temperature deviation.

The superheat reducer 4, which is located between the first steam superheater 2 and the second steam superheater 3, obtains the main steam superheated to a predetermined constant temperature by the superheat of the second steam superheater 3. In addition, the inlet side steam temperature of the second steam superheater 3 is regulated. There are two regulating means, that is, a means for adjusting the air-fuel ratio control system 18 and a means for injecting water into the superheat reducer 4.

Fuel and air are supplied to the combustion chamber 14 through an air-fuel ratio control system 18 to generate combustion heat, and the combustion gas heats steam in the second steam superheater 3 and the first steam superheater 2. After exchanging heat, the air is discharged through the flue 15. The gas in the flue 15 can be partly diverted and recycled through the recycle path 19 by the fan 20. Pure water is injected into the overheat reducer 4, and is controlled by a control system that controls the fuel supply amount while the inlet side thermometer 17 of the overheat reducer 4 measures the inlet steam temperature. That is, the control system for controlling the fuel supply amount outputs the output signal 24 of the reducer inlet side steam temperature controller 23 so that the set temperature signal 21 and the inlet side steam temperature signal 22 of the superheat reducer 4 match. Adjusts the fuel control valve 26 provided in the fuel supply pipe 25 to control the flow rate of the fuel supplied from the fuel pipe 25 to the combustion chamber 14.

At this time, a predetermined ratio of air is supplied from the air supply pipe 27 to the combustion chamber 14 by adjusting the air control valve 28 in proportion to the flow rate of the fuel supplied to the combustion chamber 14 by the air-fuel ratio control system 10. , Burn properly. The function generator 29 is a signal generator that detects the flow rate of the steam sent from the steam drum 1 and flowing through the steam pipe 16 with the flow meter 30, and outputs the setting signal 5 according to the saturated steam flow rate.

The control system for controlling the injection amount of pure water is such that the final outgoing steam signal 31 measured by the control thermometer 9 provided in the main steam pipe 13 of the second steam superheater 3 is a desired set temperature signal. In order to keep 32, the inlet side steam temperature signal 33 of the superheater 3 measured by the inlet side thermometer 8 provided on the inlet side of the second steam superheater 3 is made coincident with the final superheated steam temperature signal 34. In this way, the output signal 36 of the final outlet-side steam temperature controller 35 controls the water injection valve 5 provided in the water supply pipe 37 that sends pure water.

A temperature controller 38 that controls the temperature of the combustion gas that combusts in the combustion chamber 14 and flows through the superheater exits the combustion chamber 14 by recycling a part of the gas in the flue 15 by the recycling path 19 and the fan 20. It is for recirculating in the gas to keep the temperature of the gas passing through the steam superheater constant. As described above, conventionally, the control thermometer 9 and the backup thermometer 10 arranged in the main steam pipe 13 on the downstream side of the second steam superheater 3 are arranged so that the control thermometer 9 overheats the final outlet side. The backup thermometer 10 was used to monitor whether the main steam temperature was accurately measured.

Normally, the temperature measurement values measured by the control thermometer 9 and the backup thermometer 10 arranged close to each other show approximately the same temperature, which allows the control thermometer 9 to be accurately measured. While confirming that it is operating with the backup thermometer 10, the temperature of the superheated main steam is controlled by the procedure described above. However, deviations may occur in the temperature measurement values respectively measured by the control thermometer 9 and the backup thermometer 10, due to a failure or the like.

In this way, when there is a deviation in the temperature measurement values measured by both thermometers 9 and 10, it may not be possible to suddenly determine which is accurate and which is inaccurate. If the deviation value exceeds the allowable value, the operator switches the automatic control to manual for the time being, for example, fixing the water injection valve 5 to a certain opening that seems appropriate and supplying a certain amount of water to the overheat reducer 4. He continued the operation by taking emergency measures. When the operator finds out which thermometer is correct, for example, if the control thermometer 9 is out of order and the backup thermometer 10 is found to be accurate, the main steam thermometer The switching device 11 was switched from the control thermometer 9 side to the backup thermometer 10 side, and automatic operation was restarted to control the superheated main steam temperature.

The steam temperature of the superheater itself is controlled very finely as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-107007. However, as described above, the failure of the two main steam thermometers occurs. No specific measures have been taken against.

[0014]

[Problems to be solved by the device]

 In the above-mentioned conventional technology, if there is a deviation in the main steam temperature measured by the control thermometer and the backup thermometer, the opening of the water injection valve will be fixed, and the operator will have to complete the restoration operation. During this period, the main steam temperature control is stopped and the main steam temperature is left uncontrolled. In particular, when an abnormal deviation of the main steam temperature occurs during load change, the main steam temperature fluctuates greatly, and it becomes impossible to obtain the main steam having the desired temperature.

Further, when one of the main steam thermometers is broken or short-circuited, the correct thermometer can be easily selected, but when the indicated value is incorrect, the correct thermometer can be selected. It will be extremely difficult. It should be noted that if three thermometers are attached, it is possible to select two correct thermometers even if one thermometer is out of order, but there is a problem that construction costs and maintenance costs increase. .

In order to solve the above problems, the present invention solves the above-mentioned problems by instantly switching the correct main steam thermometer when a deviation occurs in the main steam thermometer without stopping the main steam temperature. It is an object of the present invention to provide a main steam control device for a steam superheater for a boiler, which can automatically switch meters.

[0017]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention arranges one inlet-side thermometer in the inlet-side steam pipe of the steam superheater, while controlling the thermometer and the backup temperature in the outlet-side main steam pipe of the steam superheater. In the main steam temperature controller of the steam superheater for the boiler, which has two gauges, calculate the deviation of the measured values of the main steam temperature measured by the control thermometer and the backup thermometer, and obtain the obtained temperature. If the deviation value exceeds a predetermined allowable temperature deviation value, the main steam temperature deviation judgment device determines whether the deviation value exceeds the allowable temperature deviation value. If judged, the estimated main steam temperature at the outlet side of the steam superheater is calculated from the measured temperature of the inlet steam temperature measured by the inlet thermometer of the steam superheater and the combustion conditions of the combustion gas supplied to the steam superheater. Calculate the value The main steam temperature estimator and whether the main steam estimated temperature value calculated by this main steam temperature estimator is closer to the temperature measurement value measured by the control thermometer or the backup thermometer, respectively. Main steam control thermometer selector that determines the thermometer to be used for main steam control after judging, and main steam temperature that switches the main steam control thermometer based on the selection command of this main steam control thermometer selector A main steam temperature control device for a steam superheater for a boiler, which is characterized by comprising a meter switching device.

[0018]

[Action]

 In the present invention, a deviation occurs in the temperature measurement values measured by the control thermometer and the backup thermometer arranged on the outlet side of the steam superheater, and the temperature deviation value has a predetermined allowable temperature. When the deviation value is exceeded, of the temperature measurement values measured by the two thermometers, the temperature measurement value of the inlet steam measured by the inlet side thermometer of the superheater and the temperature are supplied to the superheater. The closer to the estimated value of the main steam temperature calculated from the combustion conditions of the combustion gas, the quicker it can be judged as the correct temperature measurement value. As a result, even if one of the thermometers fails, the temperature of the main steam at the outlet of the steam superheater can always be accurately measured.

[0019]

【Example】

 Hereinafter, the configuration of the present invention will be described based on the flowchart shown in 1. In addition, in the present invention, the control thermometer 9 and the backup thermometer 10 (arrangement relationship on the upstream and downstream sides) arranged in the main steam pipe 13 connected to the outlet side of the second steam superheater 3 are provided. On the other hand, the inlet side thermometer 8 is disposed on the inlet side of the steam superheater 3 in the same manner as in the conventional example shown in FIG. The main steam temperature control device of the steam superheater for a boiler of the present invention obtains the deviation of the main steam measurement values respectively measured by the control thermometer 9 and the backup thermometer 10, and the obtained temperature deviation value is predetermined. If the main steam temperature deviation determiner 14 that determines whether the allowable temperature deviation exceeds the allowable temperature deviation and the main steam temperature deviation determiner 14 determines that the temperature deviation exceeds the allowable temperature deviation, Main steam estimated temperature on the outlet side of the steam superheater is calculated by calculation from the measured temperature of the inlet steam measured by the inlet thermometer 8 of the steam superheater 3 and the combustion conditions of the combustion gas supplied to the steam superheater 3. The main steam temperature estimator 12 for calculating the value, and the main steam estimated temperature value calculated by the main steam temperature estimator 12 are measured by the control thermometer 9 and the backup thermometer 10 respectively. Throat The main steam control thermometer selector 15 that determines the temperature gauge to be used for main steam control, and the main steam control thermometer based on the selection command of this main steam control thermometer selector. And a main steam thermometer 11 for switching between.

Next, the operation of the present invention will be described. The main steam temperature control procedure of the steam superheater for the boiler in the steady state is the same as in the case of the conventional example shown in FIG. the invention as shown in FIG. 1, enter the main steam temperature measured value t _a which is measured by the control thermometer 9 and backup temperature meter 10 of the main steam, the t _b in the main steam temperature deviation determiner 14 . In the main steam temperature deviation determinator 14, entered the main steam temperature measured value t _a, and calculates the temperature deviation Delta] t from t _b, allowable obtained temperature deviation value Delta] t is Ru Ah with predetermined temperature deviation value Delta] t _o Judgment is made.

On the other hand, from the measured temperature value T _S measured by the inlet side thermometer 8 arranged on the inlet side of the second steam superheater 3 and the combustion condition of the combustion gas supplied to the steam superheater 3, 2 Obtain the main steam temperature estimated value t _C from the calculated temperature difference ΔT _S between the inlet side and the outlet side of the steam superheater 3. t _C = T _S + ΔT _S The calculated temperature difference ΔT _S between the inlet side and the outlet side of the second steam superheater 3 is the fuel type F used in the heating chamber 14, the fuel consumption W, the air ratio. It is a value calculated from λ as follows.

ΔT _S = f (F · W · λ ...) As described above, the main steam temperature deviation determiner 14 measures the measured temperature value t _a measured by the control thermometer 9 and the backup thermometer 10. and t _b and when the temperature deviation Delta] t is determined to have exceeded the allowable temperature deviation value Delta] t _o is the main steam temperature deviation determiner 14 from the temperature measurement values t _a, the t _b main steam thermometer selector Enter in 15. In the main steam temperature thermometer selector 15 compares the input temperature measurement t _a, and t _b and the main steam temperature estimated value t _C was estimated as described above by a main steam temperature estimator 12, the main steam temperature determines whether the estimated value t _C is a value closer to one measured temperature value t _b measured by the measured temperature value t _a and backup thermometer 9 measured in the control thermometer 9.

[0023] Here, for example, a value close to the measured temperature value t _b of the main steam temperature estimate t _C was measured by the thermometer 10 for backup, a measured temperature value t _b measured by controlling the thermometer 10 If the values are far from each other, it is determined that the control thermometer 9 does not accurately measure the temperature of the main steam due to a failure or the like, and the backup thermometer 10 is selected to be used for control. . Thus, the main steam temperature thermometer selector 15 Shu蒸air temperature switching device issues a switching instruction E _X from 11 (see FIG. 2) is switched from the control thermometer 9 in the thermometer 10 side for backup, thermometer backup Use 10 as the control thermometer. The control thermometer 9 used so far is replaced with a new one or repaired and then set again.

[0024] When the main steam temperature estimate t _C if the reverse of the foregoing is close to the measured temperature value t _a which is measured by the control thermometer 9, that have far from the measured temperature value t measured by the backup thermometer 10 It goes without saying that the control thermometer 9 is continued to be used as it is, and in this case, the defective backup thermometer 10 is replaced.

[0025]

[Effect of device]

 As described above, according to the present invention, the deviation between the control temperature sensor arranged on the outlet side of the steam superheater for the boiler and the measured temperature value measured by the backup thermometer is equal to or more than the allowable temperature deviation value. In case of occurrence of the above, based on the main steam estimated temperature value calculated by calculation from the measured temperature value of steam at the inlet side of the steam superheater and the combustion conditions of the combustion gas supplied to this steam superheater Even if there are two main steam thermometers, the correct main steam thermometer can always be selected quickly.

For this reason, since the main steam thermometer can be automatically switched, even if an abnormality occurs in the main steam thermometer, the main steam temperature can always be continuously controlled without any trouble. The effect that can be achieved is enormous.

[Brief description of drawings]

FIG. 1 is a flowchart showing the configuration of the present invention.

FIG. 2 is a flowchart showing a conventional configuration.

[Explanation of symbols]

 1 Steam Drum 2 1st Steam Superheater 3 2nd Steam Superheater 4 Superheat Reducer 5 Water Injection Valve 6 Inlet Steam Temperature Controller 7 Main Steam Temperature Controller 8 Inlet Thermometer 9 Control Thermometer 10 Backup Thermometer 11 Main steam thermometer switching device 12 Main steam temperature estimator 13 Main steam pipe 14 Combustion chamber 15 Flue 16 Steam pipe 17 Inlet thermometer 18 Air-fuel ratio control system 19 Recycle path 20 Fan 21 Set temperature signal 22 Inlet steam temperature Signal 23 Reducer inlet steam temperature controller 24 Output signal 25 Fuel supply pipe 26 Fuel control valve 27 Air supply pipe 28 Air control valve 29 Function generator 30 Flow meter 31 Final outlet signal 32 Set temperature signal 33 Inlet steam temperature Signal 34 Final superheated steam temperature signal 35 Final outlet steam temperature controller 36 Output signal 37 Water injection pipe 38 Temperature controller

Claims (1)

[Scope of utility model registration request] 1. An inlet-side thermometer is arranged on the inlet-side steam pipe of the steam superheater, while two thermometers for control and backup are arranged on the outlet-side main steam pipe of the steam superheater. In the main steam temperature control device of the steam superheater for the boiler, find the deviation of the main steam temperature measured value measured by the control thermometer and the backup thermometer, and the obtained temperature deviation value is set in advance. The main steam temperature deviation determiner that determines whether or not the allowable temperature deviation value exceeds the allowable temperature deviation value, and the main steam temperature deviation determiner determines that the temperature deviation value exceeds the allowable temperature deviation value. Main steam temperature estimation to calculate the main steam estimated temperature value at the steam superheater outlet side by calculation from the measured temperature of the inlet steam temperature measured by the inlet thermometer and the combustion conditions of the combustion gas supplied to the steam superheater Bowl and this The temperature used for control of the main steam by determining which of the estimated temperature values of the main steam calculated by the main steam temperature estimator is closer to the temperature-side constant values measured by the control thermometer and the backup thermometer. A main steam control thermometer selector for selecting a meter, and a main steam thermometer switching device for switching the main steam control thermometer based on a selection command of the main steam control thermometer selector. Main steam temperature controller for steam superheater for the boiler.