JP2574972B2 - Transformer operation boiler life monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stress monitoring device for a boiler, and more particularly to a stress monitoring device for a variable-pressure operation boiler suitable for intermediate load thermal power requiring frequent starting and stopping and a large load change.

[0002]

2. Description of the Related Art Thermal equipment is in operation (especially when starting and stopping).
It is known that a thermal stress is generated in a metal part, and the metal part fatigues due to repetition of the thermal stress and eventually destroys it.

For this reason, for example, in a turbine, the rotor first
The stress of the metal part after the step is monitored, or the rate of change in the speed and load of the turbine is determined in accordance with the stress allowed for starting and stopping the turbine at one time by further considering the concept of life management. ing.

[0004] Such monitoring and control of stress has recently been required of a boiler for the first time. For example, in a constant pressure once-through boiler, a secondary superheater outlet pipe header, particularly the inner surface of a nozzle corner for a main steam pipe and a reheater outlet are required. It is known that the most excessive thermal stress is generated on the inner surface of the pipe header nozzle corner.

[0005] By the way, in recent power systems, due to an increase in the ratio of nuclear power generation and a large difference in power demand between day and night, thermal power plants have been switched to intermediate load operation with midnight start / stop and large and rapid load fluctuations. Have been forced.
As such a boiler for intermediate load operation, it is preferable to use a variable-pressure operation boiler with a small loss of fuel or the like at the time of starting and stopping.However, in order to perform starting and stopping on a daily or weekly basis, other boilers are also required. More stringent stress monitoring and control is required.

[0006]

In the case of this variable-pressure operation boiler as well, the above-mentioned nozzle corner must be used as a stress monitoring point, but it has been found that there are other parts where large stress is generated.

This is the pressure-resistant part of the steam separator of the variable-pressure operation boiler. Here, the rate of change and the width of change of the internal fluid temperature are remarkable when the plant is started and stopped. Subject to certain large fluctuations in internal pressure. Therefore, at the time of start-up, thermal stress is generated due to a temperature difference particularly generated between the pressure-resistant part metal and the internal fluid. In particular, thermal stress is large on the inner surface of a steam inlet nozzle corner having a complicated structure, and fatigue damage due to repeated stress is also large. On the other hand, during the rated operation, creep damage occurs on the inner surface of the nozzle corner due to residual stress and internal pressure stress at startup. In addition, during a load change, a repetitive stress acts due to the internal pressure fluctuation, and in the case of frequent and large load fluctuation, fatigue damage cannot be ignored.

[0008]

SUMMARY OF THE INVENTION From the foregoing, it is an object of the present invention to provide a starting bypass operation and a once-through operation of a variable- pressure operation boiler.
Boiler life suitable for monitoring stress of brackish water separator through operation
A monitoring device is provided.

[0009]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In addition, the apparatus for monitoring the life of the boiler for transformer operation of the present invention
Brackish water separator that separates heated heating feedwater into water and steam
Pressure acting on the pressure-resistant part and heat acting on the pressure-resistant part
Fatigue life consumption of the pressure-resistant part showing fatigue caused by stress
First calculating means for calculating the amount, the internal pressure stress and the heat
It shows creep damage caused by stress and heat of the heating water supply.
Second to calculate the creep damage life consumption of the pressure resistant part
Calculation means, the fatigue life consumption and the creep damage
Add the life consumption and determine whether to start the transformer operated boiler.
Life consumption of the pressure-resistant part per cycle from start to stop
A third calculating means for calculating the quantity,
The life consumption from the start of operation to the present is integrated.
A fourth calculation for calculating the cumulative life consumption of the pressure-resistant part.
Means and scheduled start-up of the transformer operated boiler planned in advance
Number of times, from the start of operation of the variable pressure operation boiler to the present
The cumulative number of startups of the variable-pressure operation boiler up to
Based on the lifetime consumption, the current
By the time, the withstand voltage section is permissible per cycle
Fifth calculating means for calculating the allowable life consumption, and the life
Comparing means for comparing the consumption with the permissible life consumption,
The deviation between the life consumption and the allowable life consumption is displayed.
Display means .

[0010]

According to the present invention, there is provided a transformer operation monitoring apparatus for a boiler,
Withstand per cycle from start to stop of operation boiler
Calculate the life consumption of the pressure section, and
Scheduled number of start-ups of the boiler and operation of the transformer boiler
Cumulative start-up of the transformer operated boiler from start to present
The number of times of operation and the
Cumulative life consumption obtained by integrating the above life consumption until
From the present to the scheduled number of starts
And the allowable life of the pressure-resistant part per cycle.
Calculate the consumption, and calculate the life consumption and the allowable life.
The difference is displayed by comparing with the life consumption. This
In addition, the operator of the variable-pressure operation boiler determines the life consumption and the
The deviation from the allowable life consumption can be quantitatively grasped.
In this case, it is possible to easily formulate an operation schedule of the variable-voltage operation boiler in consideration of the life consumption distribution.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention and shows the relationship between a boiler thermal stress monitoring device 100 using a digital computer and related input signals from a plant.

In FIG. 1, a boiler thermal stress monitoring device 100 includes a digital computer 101 and an alarm display 10.
2, a CRT display device 103, a typewriter 104, and a hard copy device 105. The digital computer 101 determines the nozzle based on the steam pressure P, the steam flow rate G, the steam temperature _Tf, and the inner metal temperature T _M1 and outer metal temperature T _M0 of the monitoring point. The thermal stress and life consumption of the inner surface of the corner are calculated at a predetermined cycle, and the thermal stress is displayed on the alarm display 102 at the time of warning and the related information is displayed on the CRT display device 103, while the typewriter 104 is displayed. Print it out. Further, the CRT display device 103 displays a trend graph display and numerical display of the calculated thermal stress value, life consumption data per start / stop and accumulated life consumption data, and the typewriter 104 displays the trend display. Other data are displayed and printed according to the operator's request.
Information such as a trend graph display displayed on the CRT display device 103 can be recorded by the hard copy device 105 on demand.

Next, the plant section in FIG. 1 will be described. The figure shows the relevant parts of the transformer Benson boiler. The operation mode of the plant is the burner 209
Until the rated load is reached after ignition, the operation is divided into the start-up bypass operation and the once-through operation. The startup bypass operation refers to an operation before the start of opening the turbine steam control valve 301 from the burner ignition. In FIG. 1, feed water is preheated by a economizer 201 of a boiler 200 and heated by a water cooling wall 202. Then, the heating fluid is steam separator 203 is separated into vapor S _F and water W _F in the water storage tank 207, the steam flash tank 208 from the bypass valve 1, the condenser 400 via the flash tank vapor dump valve 2 While being dumped to the primary superheater 204, the secondary superheater 205, and the tertiary superheater 206, the temperature is increased.

Next, in the once-through operation, the bypass valve 1 and the flash tank steam dump valve 2 are closed and the steam is
Next, flow through the tertiary superheaters 204, 205, 206,
The speed of the turbine 300 is increased by adjusting the opening of the turbine steam control valve 301 and adjusting the set value of the main steam pressure. When the turbine reaches the rated speed, a generator is inserted and the opening degree of the turbine steam control valve 301 is adjusted to satisfy the load ramping condition, and the main steam pressure is increased to the minimum pressure. Thereafter, the load control is performed by adjusting the opening degree of the turbine steam control valve 301 and the set value of the main steam pressure to the rated pressure in accordance with the load.

As described above, steam flows through the steam separator 203 through the startup bypass operation and the once-through operation.
In particular, at the time of startup, the internal fluid is exposed to a large temperature difference between the internal fluid and the metal temperature, and at the same time, the internal pressure stress greatly changes because the pressure of the internal fluid greatly changes with a load change.

FIG. 2 shows a boiler thermal stress monitoring apparatus 1 according to the present invention.
9 shows a processing procedure at 00.

The calculation units of the thermal stress, the internal pressure stress, the fatigue life consumption, and the creep rupture life consumption in this process are generally performed as follows.

First, in step 101, it is determined whether or not the boiler is in operation based on the presence or absence of the ignition signal of the burner, and if there is the ignition signal, the processing from step 102 is executed.

At step 102, a later-described step 114 is performed.
Reset the creep holding time counter required for calculating the creep damage life of the Next, in step 103, the number of times of operation, that is, the number of times the ignition signal is input is counted, and this value is used for the allowable life calculation in step 118 described later. In step 104, when one cycle from start to stop is defined as one cycle, it is determined whether or not one cycle of operation has been completed. If one cycle has not been completed, the process proceeds to the next inner surface total stress calculation step 105. Step 1
Proceed to step 17 for calculating the total life. This cycle is determined by detecting a change in the rate of temperature change (temperature gradient) in a process in which the temperature rises and stabilizes and then falls and stabilizes, for example, when starting and stopping the boiler. Is done.

In step 105, the total internal stress of the evaluation point pressure member is calculated. Here, the total internal stress refers to the internal fluid temperature Tf, pressure Pf, flow rate G,
This is a combined stress obtained by obtaining the internal pressure stress and the thermal stress in the radial, width, and circumferential directions from the outer metal temperature TMo, and combining these stresses.

In step 106, step 105
It is determined whether or not the total stress on the inner surface calculated in step S1 exceeds the allowable stress. If the stress exceeds the allowable stress, a warning is displayed in step S107 and the process proceeds to step S108. If not, the process directly proceeds to step S108. In step 108, the deviation from the normal stress value is displayed.

As described above, by displaying and outputting information related to stress, there is an effect that the operation of the boiler can be performed elastically. That is, the monitoring of the stress of the boiler is generally performed near the outlet pipe of the superheater or the reheater, but in these portions, the main steam temperature is controlled to be substantially constant when the load changes, so that the degree of fatigue life consumption is small. On the other hand, in the brackish water separator, the fatigue life consumption is large even when the load changes.

Therefore, by displaying and monitoring the information related to the stress of the steam separator, if the stress is too large at the time of start-up, the temperature raising / pressing rate is reduced, and if the stress has a margin, the operation is increased. Can do. In addition, when the load changes, it is possible to reduce the load change rate and the width of change if the stress is too large, and to increase the load if there is enough stress. Can be controlled in advance by stress monitoring.

In step 109, the internal principal stress difference is calculated in step 109A from the total internal stress obtained in step 105, and in step 109B, the fatigue life consumption for improving the design fatigue line corresponding to the stress amplitude is estimated and calculated. .

Here, the internal principal stress difference represents the principal stress in the radial direction, the axial direction, and the same direction. For example, a synthetic stress difference between the circumferential direction and the axial direction, a synthetic stress difference between the axial direction and the radial direction, and a synthetic stress difference between the radial direction and the circumferential direction.

In step 110, the equivalent stress is calculated from the inner principal stress difference calculated in step 109. This equivalent stress is a root mean square value of the above-described principal stress differences, and is used in the creep damage life calculation in step 114.

Step 111 is a part for determining whether the inner circumferential stress in the total inner stress obtained in step 105 is the tensile direction or the compressive direction, and corresponds to a first barrier for proceeding to the creep damage life calculation in step 114. I do. Here, when the inner circumferential stress acts in the compression direction, step 1 is performed to store the corresponding stress at that time as the maximum value.
If it is determined that the metal temperature is in the creep range, the process proceeds to step 113 for determining whether the metal temperature is in the creep range.

In step 112, the maximum value of the equivalent stress calculated in step 110 is determined, the average temperature of the metal at this time is stored, and the process returns to step 104. The maximum value obtained here is used in the creep damage life calculation in step 114.

Step 113 is a second barrier for proceeding to the creep damage life calculation 114, in which it is determined whether or not the average metal temperature has exceeded a set value for creep region determination.
If the average metal temperature exceeds the set value for the first time, the creep holding time counter is started, and the process proceeds to step 114. If not, the process returns to step 104.

In step 115, the maximum stress value obtained in step 112 and the average temperature of the metal at that time are used to evaluate the temperature at the time of entering the creep range based on a stress-strain diagram stored in advance. Calculate the stress at the point (initial stress).

The initial stress is the above-mentioned equivalent stress when there is no residual stress at the evaluation point, and is the sum of the residual stress and the equivalent stress when there is a residual stress.

In step 116, starting from the initial stress obtained in step 115, the stress value at the present time indicated by the creep holding time counter is obtained from a previously stored stress relaxation curve, and based on this stress value, Estimate creep damage life consumption from stored creep rupture curves.

The above steps 115 and 116 are as follows:
If the metal temperature is lower than the predetermined value and creep damage does not pose a problem, it is omitted.

Next, step 117 is a step of calculating the total life consumption, which is executed by the one-cycle end judgment given from step 104. First, step 11
In step 7A, the total life consumption of the current cycle is calculated by adding the fatigue life consumption and the creep life consumption calculated in steps 109 and 114, respectively. Step 117B
Calculates the cumulative life consumption from the start of boiler operation to the present. In step 117C, the total life consumption in the current cycle is compared with the permissible life consumption. If the permissible life consumption is larger than the permissible value, an alarm is displayed in step 117D. Step 1
In 17E, the deviation between the total life consumption and the allowable value is displayed.

Step 118 is a part for updating the permissible life consumption per cycle, and calculates the remaining number of operations and remaining life from the total number of operations obtained in step 103 and the accumulated life consumption obtained in step 117A. Then, the allowable life consumption per cycle is calculated.

That is, the accumulated life consumption already consumed is subtracted from the life determined by the material, structure, etc. of the brackish water separator, and this is obtained by subtracting the number of operations already performed from the number of planned operations. By dividing by the remaining number of operations, the allowable life consumption per one operation cycle is calculated. As a result, there is an effect that the permissible life consumption per cycle of the remaining plant start and stop operations can be grasped, and the operation schedule of the boiler can be easily set in consideration of the life consumption distribution.

[0038]

According to the present invention, a load change cycle can be simply performed.
By evaluating the life of the
Startup and shutdown are possible because the ratio of life consumption can be grasped.
A load such as a plant that frequently changes load even if it is not frequent
Flexible load operation with permissible life consumption per change possible
It works. Also, information on the total internal stress of the brackish water separator, etc.
Information is displayed and monitored during operation of the transformer,
Even when fluctuating, if the total internal stress is too large,
Reduce the rate of change and the width of change, and allow room for total internal stress
Operation such as increasing the size
It is possible to operate a simple power plant and to control the consumption life in advance. Thus, it is possible to safely and rapidly operate the load of the transformer-operated boiler.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of the embodiment shown in FIG.

[Explanation of symbols]

Reference numeral 100: boiler thermal stress monitoring device, 101: digital computer, 102: alarm display device, 103: CRT display device,
104: typewriter, 105: hard copy, 200
... boiler, 201 ... economizer, 202 ... water-cooled wall, 203 ...
Brackish water separator, 204: primary superheater, 205: secondary superheater, 206: tertiary superheater, 207: water storage tank, 208
... flash tank, 209 ... burner, 300 ... turbine, 301 ... turbine steam control valve, 400 ... condenser, 1 ...
Bypass valve, 2 ... Flash tank steam dump valve, P ...
Steam pressure, G: steam flow rate, T _f : steam temperature, MSP: main steam pressure, T _Mi : metal temperature on the inner surface of the steam separator, T _M0 : metal temperature on the outer surface of the steam separator, N _C : nozzle corner, S
_F ... steam, W _F ... water.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-81111 (JP, A) JP 4-42561 (JP, B2) "Mitsubishi Heavy Industries Technical Report" Vol. 19, No. 2 (1982) March 30, Mitsubishi Heavy Industries, Ltd.) 54-63 "Hitachi Hyoron", Vol. 65, No. 6 (published by Hitachi Hyoron, June 25, 1983) 7-12

Claims (2)

(57) [Claims] 1. A water cooling wall for heating water supply, and a water cooling wall
A brackish water separator that separates the heated heating feedwater into water and steam
Operation boiler for monitoring the life of a variable operation boiler equipped with
In the service life monitoring device, the internal pressure stress acting on the pressure resistant part of the brackish water separator and the pressure resistance
The pressure-resistant part showing fatigue caused by thermal stress acting on the part
A first calculating means for calculating the fatigue life consumption of the heat source, the internal pressure stress, the thermal stress and the heat of the heating water supply.
Creep damage life of the pressure-resistant part showing creep damage
Second calculating means for calculating the consumption , the fatigue life consumption and the creep damage life consumption
Add the 1 from the start to the stop of the variable-voltage operation boiler.
Calculating the life consumption of the pressure-resistant part per cycle
Three calculation means , before the operation of the variable pressure operation boiler until the present time
The accumulated life consumption of the pressure-resistant part is calculated by integrating the life consumption
Fourth calculating means for calculating , the planned number of startups of the transformer operating boiler planned in advance,
Before starting the operation of the above-mentioned transformer boiler until the present
The cumulative number of startups of the transformer boiler and the cumulative life consumption
From the present to the scheduled number of starts based on the amount
And the allowable life of the pressure-resistant part per cycle.
Fifth calculating means for calculating the consumption amount, and a comparison comparing the life consumption amount and the allowable life consumption amount
Means for displaying a deviation between the life consumption and the allowable life consumption.
A boiler life monitoring device, comprising: 2. The life monitoring of a boiler for a variable pressure operation according to claim 1.
In the apparatus, when the life consumption exceeds the allowable life consumption.
A variable-voltage operation boiler life monitoring device, comprising: alarm display means for displaying an alarm .