JP2004353994A - Reheated steam temperature control device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of the boiler steam temperature capable of always stable reheated steam temperature control, without deviating from a preset prefixed value, when a load changes. <P>SOLUTION: A reheating boiler sends exhaust steam after working by a high pressure turbine as reheated steam, to a medium/low pressure turbine 23 of a rear stage, by reheating the steam by a primary reheater 2 arranged in a combustion gas flow passage for flowing combustion gas generated by combustion of fuel in a furnace of a boiler, and a secondary reheater 3 on the upstream side of an exhaust gas flow of the primary reheater 2; and controls so as to operate dampers 7 and 9 in advance, by capturing the outlet temperature of the primary reheater 2 changing before the outlet temperature of the secondary reheater 3 slower in reaction than a change in the operation end, in a response to a change in opening of the dampers 7 and 9, when controlling the reheated steam temperature for sending a flow rate of boiler combustion gas supplied for heating in the primary reheater 2 and the secondary reheater 3, to the intermediate/low pressure turbine 23, by adjusting the opening of the dampers 7 and 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reheat steam temperature control method and apparatus suitable for performing stable control of reheat steam temperature.
[0002]
[Prior art]
FIG. 2 shows a process equipment configuration and a control circuit unit in the boiler, and FIG. 3 shows a detailed configuration diagram of a typical prior art of the control circuit unit in FIG. A superheater 1 and a secondary reheater 3 are arranged in a boiler furnace 6 and an exhaust gas flow path through which exhaust gas from the furnace 6 flows, and a combustion gas flow in a boiler rear heat transfer section divided into two combustion gas flow paths. A primary reheater 2 is arranged on one side of the path, and a superheater 1 and a flue evaporator 21 are arranged on the other combustion gas flow path. Exhaust steam after working with a high-pressure turbine (not shown) is supplied to a primary reheater 2, and the steam heated by the primary reheater 2 is further heated by a secondary reheater 3 to be subjected to medium / low pressure The turbine 23 is driven. The combustion gas used for heating the steam is sent to a denitration treatment device or a desulfurization device, and after being purified, is released into the atmosphere.
[0003]
A gas distribution damper 7 for distributing and controlling the amount of gas flowing through each of the two flow paths and a driving device 10 for the damper 7 are arranged at the most downstream portions of the two combustion gas flow paths of the rear heat transfer section. By controlling the flow rate of gas flowing in each flow path by controlling the opening and closing of the damper 7, the amount of heat transferred to the superheater 1, the primary reheater 2, and the flue evaporator 21 provided in the flow path is controlled. Controls the temperature of the reheated steam or the temperature of the superheated steam. Further, the combustion gas discharged from the rear heat transfer section passes through the combustion gas recirculation flow path and is circulated and supplied from the bottom of the furnace 6 into the furnace 6 again. A gas recirculation fan (GRF) 8 is disposed in the combustion gas recirculation passage, and a GRF inlet damper (or GRF inlet vane) 9 is provided on the upstream side of the fan 8 so that the damper (or vane) is provided. 9 is controlled by a drive device 11 to control the combustion gas recirculation flow rate.
[0004]
In FIG. 3, the secondary reheater outlet steam temperature set value 54 is obtained by the function generator 52 based on the boiler load signal 51, and the secondary reheater outlet steam temperature set value 54 and the secondary reheater outlet The deviation from the steam temperature signal 53 is determined by a subtractor 55, and a secondary reheater outlet steam temperature deviation signal 57 is obtained. The deviation signal 57 passes through a PID controller 56 and is added by an adder 59 to an advance signal 61 of the opening degree of the gas distribution damper 7 corresponding to the load signal 51 obtained by the function generator 60 based on the load signal 51 and added. The device output signal 62 is obtained.
[0005]
The adder output signal 62 is obtained by differentiating the load signal 51 once by a differentiator 64 and then added by a preceding signal 65 and an adder 63 to obtain a gas distribution damper operation command signal 66 to obtain a driving device for the gas distribution damper 7. 10 is driven. In response to this operation, the boiler combustion combustion gas flow path on the combustion gas flow path where the primary reheater 2 is arranged, the superheater 1 other than the primary reheater 2 and the flue evaporator The ratio of the boiler combustion gas passing through the combustion gas flow path on which the heat transfer surface such as 21 is arranged is increased or decreased, the amount of heat collected by the steam flowing inside the primary reheater 2 is adjusted, and the reheat steam temperature is controlled. .
[0006]
The gas distribution damper 7 has a mechanism in which the gas flow path on the primary reheater 2 side and the gas flow path on the superheater 1 side operate in opposite directions by mechanical linkage or linkage by an electric signal.
[0007]
Similarly, the secondary reheater outlet steam temperature deviation signal 57 is passed through a proportional controller 67 to obtain a proportional controller output signal 68, and a load signal obtained by a function generator 69 based on the signal 68 and the load signal 51. The adder 71 adds the advance signal 70 of the opening degree of the GRF entrance damper (or GRF entrance vane) 9 corresponding to 51 to obtain an adder output signal 72.
[0008]
The adder output signal 72 is obtained by differentiating the load signal 51 once by a differentiator 73 and then added to a preceding signal 74 by an adder 75 to obtain a GRF entrance damper operation command signal 76 to obtain a driving device for the GRF entrance damper 9. 11 is used for driving.
[0009]
In response to this operation, the gas recirculation amount is increased or decreased by the GRF inlet damper (or GRF inlet vane) 9, and the system of the superheater 1 and the reheater 2 arranged in the combustion gas flow path relatively far from the furnace 6. Is adjusted, and the reheat steam temperature is adjusted in the same manner as described above.
[0010]
The boiler reheat steam temperature control according to the prior art shown in FIGS. 2 and 3 uses the outlet steam temperature of the secondary reheater 3 as a feedback signal, and performs proportional (P), integral (I) and derivative (D) control. A feedback control 81 that performs so-called PID control or proportional (P) and integral (I) control, that is, so-called PI control, and an operation end position (opening of the gas distribution damper 7) for reducing a feedback control gain using a plant load signal as an index. ) And a signal component for reducing the control gain of a feedback signal consisting of a boiler acceleration command signal (BIR) obtained by differentiating the plant load signal once, that is, when the load changes. The primary reheater 2 and the speed pre-control 83 for stabilizing the control early in response to the transient heat balance are used together. It is carried out by a method of increasing or decreasing the boiler combustion gas flow rate through the following reheater 3.
[0011]
The control of the reheat steam temperature by increasing or decreasing the flow rate of the boiler combustion gas is performed, specifically, as shown in FIG. 2, a combustion gas flow path, that is, a gas flow path in which a superheater 1 and a flue evaporator 21 are installed on a boiler flue. A method of changing the ratio of the amount of heat absorbed by adjusting the opening / closing degree of the gas distribution damper by changing the ratio of the flow rate of the combustion gas passing through the gas passage and the flow rate of the combustion gas passing through the gas flow path in which the primary reheater 2 is installed, or The flow rate of the circulating combustion gas that returns the combustion gas passing through the heat transfer surface back to the furnace 6 is controlled by opening and closing the GRF inlet damper 9 to control the heat transfer surface of the furnace 6 and the superheater 1 and the reheater 2 disposed after the furnace. Is performed by a method of changing the ratio of the amount of heat absorbed by the above method.
[0012]
In an emergency such as when the reheat steam temperature rises abnormally, part of the water supply to the boiler is branched from the upstream side of the furnace 6 to a reheat steam pipe for reducing the abnormal rise in the reheat steam temperature. In some cases, a control function for reducing the reheat steam temperature by providing the reheat steam temperature reducer 5 for spraying may be used.
[0013]
In FIG. 3, when the reheat steam temperature rises or falls, the feedback control 81 appropriately reduces or increases the boiler combustion gas flow rate by P control and I control of PID control, and reheat steam by D control. This is done by making corrections with signals that decrease or increase the boiler combustion gas flow that heats the primary reheater 2, the secondary reheater 3, and in particular the primary reheater 2, according to the increasing or decreasing tendency of the temperature.
[0014]
When the load on the plant changes, the position preceding control 82 on the primary reheater 2 side determines the position of the operating end (opening degree of the damper 7) for increasing or decreasing the flow rate of the boiler combustion gas for heating the primary reheater 2 in each plant. By moving the load together with the load change to a value determined with respect to the stable state of the load, it is possible to reduce the control gain of the feedback control 81, to prevent an excessive response of the control operation at the time of the load change and thereafter, It is for controlling.
[0015]
When the plant load increases or the load decreases, the reheat steam temperature tends to temporarily increase or decrease due to a transient heat balance imbalance.
The speed leading control 83 adds a signal proportional to a signal obtained by differentiating the plant load signal once to the opening command of the operation terminal (particularly the opening of the damper 7) in order to compensate for the transient heat balance imbalance. By doing so, the flow rate of the boiler combustion gas that overheats the primary reheater 2 is increased during the load increase and decreased during the load decrease. This is to make it possible to reduce the control gain of 81, prevent an excessive response of the control operation, and perform stable control.
[0016]
Further, there is the following known example as the reheat steam temperature control.
[0017]
[Patent Document 1]
JP-A-7-113501
[Patent Document 2]
Japanese Patent Application Laid-Open No. Hei 3-20502
[Patent Document 3]
JP-A-3-20501
[Problems to be solved by the invention]
When the feedback control 81, the position preceding control 82, and the speed preceding control 83 of the related art described above are used together, the process to be controlled when the opening degree of the operation terminals (dampers 7, damper 9) used for the control is changed. If the time until the amount (reheated steam temperature) changes is extremely long, it is difficult to perform stable control.
[0021]
That is, when the reheat steam temperature is controlled by the opening degree of the gas distribution damper 7 and the boiler gas circulation damper 9 to which the present invention is applied, the opening degree of the gas distribution damper 7 and the boiler gas circulation damper 9 is changed, and then the reheating steam temperature is changed. The time until the heat steam temperature changes is very long, and there is an example in which the dead time is about 2 minutes and the time constant is about 10 minutes as shown in FIG.
[0022]
On the other hand, when the load is changed, the reheaters 2 and 3 are immediately affected by the change in the heat balance of the burner and are affected by the change in the heat balance of the entire plant. ), A rapid change in the reheat steam temperature starts to appear relatively early (Tp = 3 minutes) after the load change starts.
[0023]
Therefore, in the related art in which the feedback control 81, the position preceding control 82, and the speed preceding control 83 are only used in combination with the reheat steam temperature control, the adjustment is focused on suppressing the sudden reheat steam temperature change immediately after the start of the load change. Is performed, the response speed of the process amount to the change of the operation end (damper 7, damper 9) is too slow, so that it is necessary to adjust the feedback control component and the speed preceding control component excessively to compensate for the change.
[0024]
As a result, as shown in FIG. 4C, even if the fluctuation of the reheat steam temperature can be suppressed immediately after the start of the load change, the influence of the operation of the component of the feedback control 81 and the operation of the component of the speed preceding control 83 will be shortly after. Acts with a delay, and the temperature violently swings back in the direction opposite to the operation direction immediately after the start of the load change.
[0025]
This is because the speed leading control 83 component has been continuously entered from the start to the end of the load change at a high level for suppressing the temperature fluctuation immediately after the start of the load change, and its action has been delayed and appears as an adverse effect.
[0026]
It is an object of the present invention to solve such a problem and to control a boiler steam temperature capable of always performing a stable reheat steam temperature control without deviating from a preset value set when a load changes.
[0027]
[Means for Solving the Problems]
In order to solve the above-mentioned problem of the present invention, in order to improve that the effect on the process to be controlled is slow due to a change in the operation end, a process amount that changes prior to the slow process to be controlled is captured in advance. A method of controlling the operation terminal to operate is adopted.
[0028]
Therefore, in response to the change in the opening degree of the gas distribution damper, the dead time in the exhaust gas flow path from the boiler furnace 6 is smaller than the dead steam temperature of the outlet steam temperature of the secondary reheater 3 disposed in the upstream flow path. Reheat the outlet steam temperature of the primary reheater 2 disposed in the boiler rear heat transfer section, which is a downstream flow path having a time constant of about 1.5 to 1.5 minutes and a time constant of about 1.5 to 3 minutes. It is applied to steam temperature control and mainly adopts the following configuration.
[0029]
In a reheat-type boiler that reheats high-pressure turbine exhaust steam in a primary reheater 2 and a secondary reheater 3 and feeds the reheat steam to a subsequent middle / low-pressure turbine 23, the primary reheater 2 And a device for controlling the temperature of the reheat steam sent to the middle / low pressure turbine 23 by adjusting the flow rate of the boiler combustion gas used for heating in the secondary reheater 3. A feedback proportional signal component of the outlet steam temperature of the primary reheater 2 is added to the temperature feedback proportional / integral control signal to adjust the flow rate adjustment signal of the boiler combustion gas.
[0030]
That is, the present invention has the following configuration.
(1) A primary reheater having a horizontal heat transfer surface disposed in a combustion gas flow path through which a combustion gas generated by combustion of fuel in a furnace of a boiler flows, and an exhaust gas flow upstream of the primary reheater After the exhaust steam after working with the high-pressure turbine is sequentially supplied to the secondary reheater having the suspended-type heat transfer surface on the side and reheated by the combustion gas, it is disposed at the subsequent stage of the high-pressure turbine. -In the reheat steam temperature control method of the reheat type boiler that sends air as reheat steam to the low pressure turbine,
Based on the feedback proportional / integral control signal component based on the difference between the secondary reheater outlet steam temperature and the set temperature corresponding to the load signal, based on the difference between the primary reheater outlet steam temperature and the set temperature corresponding to the load signal A reheat steam temperature control method for adding a feedback proportional control signal component to adjust a flow rate of boiler combustion gas for reheat steam heating in the primary reheater and the secondary reheater.
[0031]
In the reheat steam temperature control method, the adjustment of the flow rate of the boiler combustion gas is performed by disposing the primary reheater disposed on one of the combustion gas flow paths that divides the combustion gas flow path of the boiler and the other on the other combustion gas flow path. The degree of opening of the gas distribution damper for changing the flow rate of the combustion gas to the heat transfer surface and / or the circulation provided in the boiler combustion gas circulation path for returning the combustion gas exiting the boiler combustion gas path to the furnace again A method performed by adjusting the opening degree of the damper may be adopted.
[0032]
(2) A primary reheater having a horizontal heat transfer surface disposed in a combustion gas flow path through which a combustion gas generated by combustion of fuel in a furnace of a boiler flows, and an exhaust gas flow upstream of the primary reheater. After the exhaust steam after working with the high-pressure turbine is sequentially supplied to the secondary reheater having the suspended-type heat transfer surface on the side and reheated by the combustion gas, it is disposed at the subsequent stage of the high-pressure turbine. A flow rate of the boiler combustion gas for adjusting the flow rate of the boiler combustion gas for heating the reheat steam in the primary reheater and the secondary reheater in the reheat type boiler that feeds the reheat steam to the low pressure turbine A reheat steam temperature control device comprising an adjusting means, for controlling a reheat steam temperature to be sent to the medium / low pressure turbine by a flow rate of the boiler combustion gas by the boiler combustion gas flow rate adjusting means,
Feedback proportional / integral control means based on the difference between the secondary reheater outlet steam temperature and the set temperature corresponding to the load signal, and feedback based on the difference between the primary reheater outlet steam temperature and the set temperature corresponding to the load signal Adding means for adding the signal obtained by the feedback proportional control means of the primary reheater outlet steam temperature to the signal obtained by the proportional control means and the feedback proportional / integral control means of the secondary reheater outlet steam temperature; Adjusting the flow rate of the boiler combustion gas by the flow rate adjusting means for the boiler combustion gas for reheating steam in the primary reheater and the secondary reheater based on the added value obtained by the addition means. Hot steam temperature control device.
[0033]
The flow rate adjusting means of the boiler combustion gas of the reheat steam temperature control device is disposed, for example, in a primary reheater disposed in one combustion gas flow path that divides a combustion gas flow path of a boiler into two and in the other combustion gas flow path. Drive means for adjusting the opening degree of the gas distribution damper for changing the flow rate of the combustion gas to the heat transfer surface to be heated and / or the boiler combustion gas circulation flow for returning the boiler combustion gas exiting the boiler combustion gas flow path to the furnace again A boiler gas circulation damper provided on the road and a driving means for adjusting the opening thereof are used.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
A reheat steam temperature control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a reheat steam temperature control circuit of the present embodiment used for the process equipment configuration and the control circuit unit in the boiler shown in FIG. The features of the reheat steam temperature control circuit according to the embodiment of the present invention shown in FIG. 1 are as follows.
[0035]
That is, the secondary reheater outlet steam temperature signal 53 is subtracted by the subtractor 55 between the secondary reheater outlet steam temperature set value 54 obtained by the function generator 52 according to the load signal, The secondary reheater outlet steam temperature deviation 57 is obtained. The deviation signal 57 is added via a PID controller 56 to a gas distribution damper opening advance signal 61 obtained by a function generator 60 in accordance with a load signal 51 and an adder 59 in accordance with a load signal 51. The BIR signal 65 for the gas distribution damper that has been differentiated once by the differentiator 64 is added to the adder 63 to obtain an added value 77.
[0036]
Further, a difference between the primary reheater outlet steam temperature set value 92 obtained by the function generator 91 according to the primary reheater outlet steam temperature signal 110 and the load signal 51 is obtained by the subtractor 93, and is obtained. The primary reheater outlet steam temperature deviation 94 is added to the added value 77 by an adder 97 as an output signal 96 of a P (proportional) controller 95 to obtain a gas distribution damper operation command 66 to drive the gas distribution damper 7. The device 10 is operated.
[0037]
In response to this operation, the degree of opening of the gas distribution damper 7 is adjusted, so that the gas flow path of the heat transfer section at the rear of the boiler in which the primary reheater 2 is arranged and the reheating of the superheater 1 and the flue evaporator 21 are performed. The ratio of the boiler combustion gas passing through the gas flow path on which the heat transfer surfaces other than the heat exchanger is arranged is increased or decreased, the amount of heat collected by the steam flowing inside the primary reheater 2 is adjusted, and the reheat steam temperature is controlled. . The gas distribution damper 7 has a mechanism in which the gas flow path on the primary reheater 2 side and the gas flow path on the superheater 1 side operate in opposite directions by mechanical linkage or linkage by an electric signal.
[0038]
The difference between the reheat steam temperature control circuit of the embodiment of the present invention shown in FIG. 1 and the prior art shown in FIG. 3 is that the reheat steam temperature control circuit of the primary reheater 2 has a quick response to a change in the opening degree of the gas distribution damper 7. This is the point where the proportional controller output signal 96 of the temperature deviation 94 between the outlet steam temperature signal 110 and the set value 92 for the load signal 51 is added by the adder 97. In the related art, since the feedback control 81 based on the outlet steam temperature signal 53 of the secondary reheater 3 having a slow response to the change in the opening degree of the gas distribution damper 7 is performed, the control is not returned until the temperature is inverted. There was a problem.
[0039]
Therefore, in the embodiment of the present invention shown in FIG. 1, by returning the gas distribution damper 7 earlier with a process amount that responds quickly to the change in the opening degree of the gas distribution damper 7, the load deviates from a preset value set in advance when the load changes. In addition, it has become possible to control the boiler steam temperature, which enables stable reheat steam temperature control at all times.
[0040]
Similarly, the secondary reheater outlet steam temperature deviation signal 57 is obtained by obtaining a proportional controller output signal 68 by the proportional controller 67 and obtaining the GRF obtained by the function generator 69 in accordance with the signal 68 and the load signal 51. An inlet damper opening advance signal 70 is added by an adder 71, and a load signal 51 is differentiated by a differentiator 73 once and a GRF inlet damper opening advance signal 74 is added by an adder 75. The sum 78 obtained by the adder 75 is further between the primary reheater outlet steam temperature signal 110 and the primary reheater outlet steam temperature set value 99 obtained by the function generator 98 in response to the load signal 51. The subtractor 100 performs the subtraction. The primary reheater outlet steam temperature deviation 101 obtained by the subtractor 100 is added to the addition value 78 by an adder 104 as an output signal 103 of a P (proportional) controller 102 to obtain a GRF inlet damper operation command 76. The driving device 11 for the GRF entrance damper 9 is operated.
[0041]
In response to this operation, the gas recirculation amount is increased or decreased by the GRF inlet damper (or GRF inlet vane) 9, and the heat absorption amount of the reheater system arranged downstream of the flue relatively far from the furnace 6. Is adjusted, and the reheat steam temperature is adjusted as described above.
[0042]
The control of the amount of gas recirculation by the GRF inlet damper (or GRF inlet vane) 9 also allows the outlet steam temperature signal 110 of the primary reheater 2 to respond quickly to a change in the opening degree of the GRF inlet damper (or GRF inlet vane) 9. The proportional controller output signal 103 of the temperature deviation 101 between the load signal 51 and the set value 99 with respect to the load signal 51 is added by the adder 104 to the addition value 78 obtained by the adder 75, and the GRF inlet damper (or GRF inlet vane) 9 Is quickly returned by the process amount (outlet steam temperature signal 110 of the primary reheater 2) which has a relatively quick response to the change of the opening degree, so that the load does not deviate from the preset value at the time of load change and is always stable. It has become possible to control the boiler steam temperature, which enables the reheat steam temperature control.
[0043]
【The invention's effect】
According to the present invention, there is an effect that the reheat steam temperature can be controlled stably.
Even when the load changes, the control signal according to the prior art for adjusting the flow rate of the boiler combustion gas passing through the reheater includes a control signal from the primary reheater outlet steam temperature deviation that responds quickly to a change in the gas distribution damper opening. By adding the proportional control load signal, stable control can always be performed without the secondary reheater outlet steam temperature largely deviating from the set value.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating details of a reheat steam temperature control circuit unit according to an embodiment of the present invention.
FIG. 2 is a diagram showing a process device configuration and a control circuit unit related to reheat steam temperature control.
FIG. 3 is a diagram illustrating details of a reheat steam temperature control circuit unit according to the related art.
FIG. 4 is a diagram showing a response characteristic of a reheat steam temperature to a gas distribution damper step operation and a load change, and a temperature response characteristic at the time of a load change according to the related art.
[Explanation of symbols]
Reference Signs List 1 superheater 2 primary reheater 3 secondary reheater 5 reheat steam temperature reducer 6 boiler furnace 7 gas distribution damper 8 gas recirculation fan 9 GRF inlet damper (or GRF inlet vane)
Reference Signs List 10 Drive for gas distribution damper 11 Drive for GRF inlet damper 21 Flue gas evaporator 23 Medium / low pressure turbine 51 Load signal 52 Function generator 53 Secondary reheater outlet steam temperature signal 54 Secondary reheater outlet steam temperature Set value 55 Subtractor 56 PID controller 57 Secondary reheater outlet steam temperature deviation signal 59, 63 Adder 60 Function generator 61 Gas distribution damper opening advance signal 62 Adder output signal 64 Differentiator 65 For gas distribution damper BIR signal (speed advance signal)
66 Gas distribution damper operation command signal 67 Proportional controller 68 Proportional controller output signal 69 Function generator 70 GRF inlet damper opening advance signal 71 Adder 72 Adder output signal 73 Differentiator 74 GRF inlet damper opening advance signal 75 Addition 76 GRF entrance damper operation command (signal)
77 Addition value 78 Addition value 81 Feedback control 82 Position leading control 83 Speed leading control 91 Function generator 92 Primary reheater outlet steam temperature set value 93 Subtractor 94 Primary reheater outlet steam temperature deviation 95 P (proportional) controller 96 Proportional controller output signal 97 Adder 98 Function generator 99 Primary reheater outlet steam temperature set value 100 Subtractor 101 Primary reheater outlet steam temperature deviation 102 P (proportional) controller 103 Proportional controller output signal 104 Addition Vessel 110 Primary reheater outlet steam temperature signal

Claims (4)

A primary reheater having a horizontal heat transfer surface disposed in a combustion gas flow path through which combustion gas generated by combustion of fuel in a furnace of a boiler flows, and a suspension on an upstream side of an exhaust gas flow from the primary reheater; After the exhaust steam after working with the high-pressure turbine is sequentially supplied to the secondary reheater having the lower heat transfer surface and reheated by the combustion gas, the medium- and low-pressure turbines are disposed at the subsequent stage of the high-pressure turbine. In the reheat steam temperature control method of a reheat type boiler that sends air as reheat steam to
Based on the feedback proportional / integral control signal component based on the difference between the secondary reheater outlet steam temperature and the set temperature corresponding to the load signal, based on the difference between the primary reheater outlet steam temperature and the set temperature corresponding to the load signal A reheat steam temperature control method, comprising adding a feedback proportional control signal component and adjusting a flow rate of a boiler combustion gas for heating reheat steam in the primary reheater and the secondary reheater. Adjustment of the flow rate of the boiler combustion gas is performed by dividing the combustion gas flow path of the boiler into two in the primary reheater disposed in one combustion gas flow path and the combustion gas flowing to the heat transfer surface disposed in the other combustion gas flow path. By adjusting the opening of the gas distribution damper for changing the flow rate ratio and / or the opening of the circulation damper provided in the boiler combustion gas circulation channel for returning the combustion gas exiting the boiler combustion gas channel to the furnace again. The reheat steam temperature control method according to claim 1, wherein the method is performed. A primary reheater having a horizontal heat transfer surface disposed in a combustion gas flow path through which combustion gas generated by combustion of fuel in a furnace of a boiler flows, and a suspension on an upstream side of an exhaust gas flow from the primary reheater; After the exhaust steam after working with the high-pressure turbine is sequentially supplied to the secondary reheater having the lower heat transfer surface and reheated by the combustion gas, the medium- and low-pressure turbines are disposed at the subsequent stage of the high-pressure turbine. Boiler combustion gas flow rate adjusting means for adjusting the flow rate of boiler combustion gas for heating the reheat steam in the primary reheater and the secondary reheater in the reheat type boiler which sends air as reheat steam to A reheat steam temperature control device for controlling a reheat steam temperature to be sent to the medium / low pressure turbine according to a flow rate of the boiler combustion gas by the flow rate adjustment means for the boiler combustion gas; Its load signal A feedback proportional-integral controller based on the deviation of the corresponding set temperature,
Feedback proportional control means based on the deviation of the set temperature corresponding to the primary reheater outlet steam temperature and its load signal,
Adding means for adding the signal obtained by the feedback proportional control means of the primary reheater outlet steam temperature to the signal obtained by the feedback proportional / integral control means of the secondary reheater outlet steam temperature,
The flow rate of the boiler combustion gas is adjusted by the flow rate adjustment means for the boiler combustion gas for heating the reheat steam in the primary reheater and the secondary reheater based on the addition value obtained by the addition means. Reheat steam temperature control device. The boiler combustion gas flow rate adjusting means includes a primary reheater disposed in one combustion gas flow path that bisects the combustion gas flow path of the boiler, and a combustion gas flow to a heat transfer surface disposed in the other combustion gas flow path. A drive means for adjusting the opening of the gas distribution damper for changing the flow rate ratio and / or a boiler gas circulation damper provided in the boiler combustion gas circulation path for returning the boiler combustion gas exiting the boiler combustion gas path to the furnace again. 4. The reheat steam temperature control device according to claim 3, wherein the drive means is a driving means for adjusting the opening degree.

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