JP2007132630A - Boiler reheating steam temperature control device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler reheating steam temperature control device having good controllability without deteriorating turbine efficiency. <P>SOLUTION: The boiler reheating steam temperature control device performs the temperature control of a reheater 14 of a boiler by using a reheater outlet damper 15 and an temperature reducer spray water flow rate adjusting valve 17 based on deviation between the outlet temperature of a superheater of the boiler and the outlet temperature of the reheater. The boiler reheating steam temperature control device is equipped with an temperature reducer spray water flow rate control part 20 for adjusting a temperature reducer spray water flow rate by the temperature reducer spray water flow rate adjusting valve 17, and a reheater outlet damper control part 19 for adjusting an opening of the reheater outlet damper so that an opening command of the temperature reducer spray water flow rate adjusting valve 17 is zero and controlling a reheater outlet steam temperature to a set value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boiler using a reheater outlet damper and a desuperheater spray water flow control valve based on the deviation between the outlet temperature of the superheater of the boiler of the thermal power plant and the outlet temperature set value of the reheater. TECHNICAL FIELD The present invention relates to a boiler reheat steam temperature control apparatus and method for controlling the temperature of a reheater.

  Thermal power plants include thermal power plants for business use or IPP (Independent Power Producer). Usually, these thermal power plants have boilers. There is also a thermal power plant having a reheat steam system in which steam generated in a boiler is guided to a high-pressure turbine, and steam that has finished work in the high-pressure turbine is again heated by a reheater and guided to a low-pressure turbine. In such a thermal power plant, the reheat steam temperature is controlled by reheater outlet damper control and desuperheater spray water flow rate control (for example, refer to Patent Document 1).

  FIG. 9 is a block diagram of a boiler reheat steam temperature control device in a conventional thermal power plant. Steam generated in the boiler is temperature-controlled by the superheater 11 and the temperature reducer 12 and supplied to the high-pressure turbine 13. The steam that has finished work in the high-pressure turbine 13 is once heated by the reheater 14 of the boiler, the temperature is adjusted by the reheater outlet damper 15, and is guided to the low-pressure turbine 16. The temperature of the temperature reducer 12 is adjusted by the amount of spray water from the spray water flow rate adjustment valve 17.

  Temperature control of the reheat steam supplied to the low-pressure turbine 16 is performed by the boiler reheat steam temperature control device 18. The boiler reheat steam temperature control device 18 adjusts the opening of the reheater outlet damper 15 to control the reheater outlet steam temperature to a set value, and the desuperheater spray water. The flow control valve 17 is configured to include a temperature reducer spray water flow rate control unit 20 that adjusts the flow rate of the temperature reducer spray water and controls the reheater outlet steam temperature to a set value.

  The reheater outlet damper control unit 19 takes a deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the subtractor 21, performs control calculation by the PID controller 22, and performs a reheater outlet damper. 15 is controlled. The temperature reducer spray water flow rate control unit 20 adds the reheater outlet temperature set value Tr1 and the bias value Tb by the adder 23, and the subtractor 24 adds the deviation between the added signal and the superheater outlet temperature T1. Calculate. Then, the deviation ΔT2 obtained as a result is subjected to a control calculation by the PID controller 25, and the opening degree limiter 26 limits the opening degree of the temperature reducer spray water flow rate adjustment valve 17. That is, the temperature reducer spray water flow rate control unit 20 is configured to operate as a backup when the temperature deviation ΔT1 increases.

Although the control by the desuperheater spray water flow rate control unit 20 has good controllability, there is a decrease in efficiency due to spraying spray water, and the control by the reheater outlet damper control unit 19 has a large time constant and poor controllability. The decrease in efficiency is small. Therefore, emphasizing efficiency, priority is given to reheater outlet damper control, and desuperheater spray water flow control is used as a backup.
JP-A-8-135405

  However, in the conventional boiler reheat steam temperature control device, controllability is poor because priority is given to reheater outlet damper control with a large time constant. In addition, since the controllability of the reheater outlet damper control is poor, if the desuperheater spray water flow rate control is operated, the temperature control is performed by spraying the spray water in the desuperheater spray water flow rate control, so the turbine efficiency is reduced. It will be.

  An object of the present invention is to provide a boiler reheat steam temperature control apparatus and method having good controllability without reducing turbine efficiency.

  The boiler reheat steam temperature control device of the present invention is based on the deviation between the boiler superheater outlet temperature and the reheater outlet temperature set value, and the reheater outlet damper, the desuperheater spray water flow control valve, In the boiler reheat steam temperature control device, which controls the temperature of the boiler reheater using the chiller, the reheater outlet steam temperature is set by adjusting the desuperheater spray water flow rate with the desuperheater spray water flow rate control valve The reheater outlet is controlled by adjusting the opening of the reheater outlet damper so that the opening command of the desuperheater spray water flow rate control valve and the desuperheater spray water flow rate control valve are set to zero. And a reheater outlet damper controller that controls the steam temperature to a set value.

  The boiler reheat steam temperature control method of the present invention is based on a deviation between a boiler superheater outlet temperature and a reheater outlet temperature set value, and a reheater outlet damper, a desuperheater spray water flow control valve, In the boiler reheat steam temperature control method, which controls the temperature of the boiler reheater using the temperature controller, the reheater outlet steam temperature is set by adjusting the desuperheater spray water flow rate with the desuperheater spray water flow rate control valve. The temperature of the desuperheater spray water is controlled to a value, and the reheater outlet steam temperature is adjusted by adjusting the opening of the reheater outlet damper so that the opening command of the desuperheater spray water flow control valve is zero. Is controlled to a reheater outlet damper to a set value.

  According to the present invention, the desuperheater spray water flow control for adjusting the desuperheater spray water flow rate to control the reheater outlet steam temperature to its set value, and the opening degree of the desuperheater spray water flow rate control valve. Since the reheater outlet damper control that adjusts the reheater outlet damper opening so that the command becomes zero is operated in cooperation, the reheater maintains good controllability without reducing turbine efficiency. The outlet steam temperature can be controlled.

(First embodiment)
FIG. 1 is a configuration diagram of a boiler reheat steam temperature control apparatus according to a first embodiment of the present invention. The boiler reheat steam temperature control device 18 adjusts the opening of the reheater outlet damper 15 to control the reheater outlet steam temperature to a set value, and the desuperheater spray water. The flow control valve 17 is configured to include a temperature reducer spray water flow rate control unit 20 that adjusts the flow rate of the temperature reducer spray water and controls the reheater outlet steam temperature to a set value.

  The desuperheater spray water flow rate controller 20 subtracts the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the subtractor 24, and the PID controller 25 controls and calculates the deviation ΔT3 obtained as a result. The opening degree of the desuperheater spray water flow rate adjustment valve 17 is adjusted through the opening degree limiter 26.

  On the other hand, the reheater outlet damper control unit 19 sets the zero opening command value H0 of the temperature reducer spray water flow rate adjustment valve 17 as a set value, and opens the temperature reducer spray water flow rate adjustment valve 17 from the PID controller 25. The deviation ΔH from the degree required value H is calculated by the subtractor 27, and the opening degree of the reheater outlet damper 15 is adjusted by the PID controller 28 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero. Adjust. That is, the reheater outlet damper control unit 19 adjusts the opening degree of the reheater outlet damper 15 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero, and the reheater outlet steam. Control the temperature to the set value.

  In this case, the temperature controller spray water flow rate control and reheater outlet damper control are different from the control method in the conventional boiler reheat steam temperature control device in that control using separate set values and process values is used. Therefore, both control systems do not interfere with each other.

  According to the first embodiment, since the desuperheater spray water flow control and the reheater outlet damper control are operated in cooperation with each other, the desuperheater spray water with good controllability is provided for a rapid temperature change. On the other hand, the flow rate can be controlled, while the reheater outlet damper control can balance slowly at the operating point where the spray water becomes zero. For this reason, the opening degree of the desuperheater spray water flow rate control valve 17 is suppressed, the flow rate of the spray water is reduced, and a decrease in efficiency can be prevented.

(Second Embodiment)
FIG. 2 is a block diagram of a boiler reheat steam temperature control apparatus according to the second embodiment of the present invention. As shown in FIG. 2, the boiler reheat steam temperature control device 18 adjusts the opening of the reheater outlet damper 15 to control the reheater outlet steam temperature to a set value. And a desuperheater spray water flow rate control unit 20 for adjusting the desuperheater spray water flow rate by the desuperheater spray water flow rate regulating valve 17 and controlling the reheater outlet steam temperature to a set value.

  The reheater outlet damper control unit 19 includes a first control system 29 that adjusts the opening degree of the reheater outlet damper so that the superheater outlet temperature becomes the reheater outlet temperature set value, and the desuperheater spray water flow rate. And a second control system 30 that adjusts the opening degree of the reheater outlet damper so that the opening degree command of the control valve 17 becomes zero, and the superheater outlet temperature T1 is set to the reheater outlet temperature set value Tr1. When the comparison result of the comparator 31 is “below” or not, the output of the first control system 29 is selected and not “below” or less. And a switch 32 for selecting the output of the second control system 30.

  On the other hand, the desuperheater spray water flow rate controller 20 adds the reheater outlet temperature set value Tr1 and the bias value Tb by the adder 23, and subtracts the deviation between the added signal and the superheater outlet temperature T1. 24. Then, the deviation ΔT2 obtained as a result is subjected to a control calculation by the PID controller 25, and the opening degree limiter 26 limits the opening degree of the temperature reducer spray water flow rate adjustment valve 17.

  That is, the reheater outlet damper control unit 19 controls and calculates the deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the PID controller 22, and controls the reheater outlet damper 15. The control system by the first control system 29 and the zero opening command value H0 of the desuperheater spray water flow rate adjustment valve 17 are set as set values, and the opening command of the desuperheater spray water flow rate adjustment valve 17 is set by the PID controller 28. And the control system by the second control system that adjusts the opening degree of the reheater outlet damper 15 so as to be zero.

  Then, the subtractor 24 calculates a deviation (Tr1 + Tb−T1) between the added value (Tr1 + Tb) obtained by adding the reheater outlet temperature set value Tr1 and the bias value Tb by the adder 23 and the superheater outlet temperature T1, The resulting deviation ΔT2 is compared by the comparator 31. As a result of the comparison, when the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb), the switcher 32 selects the output of the second control system 30. That is, the reheater outlet damper control unit 19 adjusts the opening degree of the reheater outlet damper 15 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero, and the reheater outlet steam temperature. Is controlled to the set value.

  When the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb), the temperature reducer spray water flow rate control unit 20 is in a state in which the temperature reducer spray water flow rate control is operated. Control is also performed. Thereby, coordinated control of the temperature reducer spray water flow rate control and the reheater outlet damper control is performed. Therefore, the opening degree of the desuperheater spray water flow rate control valve 17 is suppressed, and the flow rate of the spray water is reduced, thereby preventing a reduction in efficiency.

  Further, as a result of the comparison by the comparator 31, when the superheater outlet temperature T1 is smaller than the added value (Tr1 + Tb), the first control system 29 is selected by the switch 32. That is, when the superheater outlet temperature T1 is smaller than the added value (Tr1 + Tb), the temperature controller spray water flow rate control by the temperature reducer spray water flow rate control unit 20 does not operate. Control is performed such that the deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 is eliminated.

  According to the second embodiment, switching between reheater outlet damper control by the first control system 29 and cooperative control between the desuperheater spray water flow rate control and the reheater outlet damper control by the second control system is performed. Because it has a function, it can be controlled so that the flow rate of the spray water is minimized, and a decrease in efficiency can be prevented.

(Third embodiment)
FIG. 3 is a block diagram of a boiler reheat steam temperature control apparatus according to the third embodiment of the present invention. In the third embodiment, a gate circuit 33 is added to the second embodiment shown in FIG. 2, and the gate circuit 33 is opened by a switching command signal S from the operator. is there. Since the other configuration is the same as that of the second embodiment shown in FIG.

  As shown in FIG. 3, the switching command signal S by the operator is input to the gate circuit 33. The output of the comparator 31 is also input to the gate circuit 33, and the comparator 31 outputs a logical value “1” when the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb). Therefore, the gate circuit 33 permits the output signal of the comparator 31 to be output to the switch 32 when the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb).

  Thereby, in the normal state, the reheater outlet damper 15 is controlled by the output signal of the first control system 29, and the comparator 31 determines that the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb). When there is a switching command signal S from the operator, switching from the output signal of the first control system 29 to the output signal of the second control system 30 is performed, and the output signal of the second control system 30 is restarted. The heater outlet damper 15 is controlled.

  According to the third embodiment, the switching condition of the switching device 32 is the AND condition between the satisfaction of the condition of the comparator 31 and the switching command signal S of the operator, so the first control system 29 is determined by the operator. It is possible to switch between the reheater outlet damper control by the above and the reheater outlet damper control by the second control system. That is, the cooperative control of the desuperheater spray water flow rate control and the reheater outlet damper control by the second control system can be selected by the operator's judgment.

(Fourth embodiment)
FIG. 4 is a block diagram of a boiler reheat steam temperature control apparatus according to the fourth embodiment of the present invention. In the fourth embodiment, a function generator 34 is provided with respect to the first embodiment shown in FIG. 1, and the regenerator outlet temperature set value Tr1 and the superheater outlet temperature are provided by the function generator 34. Based on the deviation ΔT3 from T1, the gain of the PID controller 28 of the reheater outlet damper controller 19 is made variable. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 4, the subtractor 24 obtains the cooperative control of the desuperheater spray water flow rate control by the desuperheater spray water flow rate control unit 29 and the reheater outlet damper control by the reheater outlet damper control unit 19. A deviation ΔT3 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 is input to the function generator 34, and the function generator 34 calculates the gain of the PID controller 28 based on the deviation ΔT3.

  When the deviation ΔT3 is negative, the gain calculated by the function generator 34 is calculated so as to increase as the absolute value increases. As a result, the temperature reducing operation of the reheater outlet damper 15 is increased, and the spray water flow rate due to the opening operation of the temperature reducer spray water flow rate adjusting valve 17 is decreased.

  According to the fourth embodiment, the gain of the PID controller 28 of the reheater outlet damper control unit 19 is variable based on the deviation ΔT3 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1. Since the gain is increased as the deviation ΔT3 becomes negative, the temperature reducing operation of the reheater outlet damper 15 is increased and the spray water flow rate by the opening operation of the temperature reducing device spray water flow rate adjusting valve 17 is minimized. This can prevent the boiler efficiency from being lowered.

(Fifth embodiment)
FIG. 5 is a block diagram of a boiler reheat steam temperature control apparatus according to the fifth embodiment of the present invention. This fifth embodiment is different from the second embodiment shown in FIG. 2 in that a function generator 34 is provided in the second control system 30 of the reheater outlet damper control unit 19, and this function generator 34 Thus, based on the difference ΔT2 between the added value (Tr1 + Tb) obtained by adding the bias value Tb to the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1, the PID controller 28 of the reheater outlet damper control unit 19 The gain is variable. The same elements as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  The boiler reheat steam temperature control device 18 shown in FIG. 5 includes a reheater outlet damper control by the first control system 29 of the reheater outlet damper control unit 19 and a second control system of the reheater outlet damper control unit 19. It has a function of switching between 30 reheater outlet damper control and cooperative control of the desuperheater spray water flow rate control.

  In the boiler reheat steam temperature control device 18, the gain of the PID controller 28 of the second control system that performs coordinated control of the desuperheater spray water flow rate control and the reheater outlet damper control is variable by the function generator 34. To do. The function generator 34 calculates the gain based on the difference ΔT2 between the addition value (Tr1 + Tb) obtained by adding the bias value Tb to the reheater outlet temperature set value Tr1 obtained by the subtractor 24 and the superheater outlet temperature T1. The variable gain calculated by the function generator 34 is increased as the deviation ΔT2 becomes negative.

  According to the fifth embodiment, the reheater outlet damper control unit is based on the deviation ΔT2 between the added value (Tr1 + Tb) obtained by adding the bias value Tb to the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1. 19, the gain of the PID controller 28 is made variable, and the gain is increased as the deviation ΔT3 becomes negative. Therefore, the temperature reducing operation of the reheater outlet damper 15 is increased, and the temperature reducing device spray water flow rate adjusting valve 17 is opened. It becomes the control which makes the spray water flow rate by minimum become possible, and the fall of the efficiency of a boiler can be prevented.

(Sixth embodiment)
FIG. 6 is a block diagram of a boiler reheat steam temperature control apparatus according to the sixth embodiment of the present invention. The sixth embodiment is different from the second embodiment shown in FIG. 2 in that a comparison selector 35 is provided in place of the comparator 31 and the switch 32, and the comparison selector 35 provides a first control system. The larger one of the output of 29 and the output of the second control system 30 is selected and output to the reheater outlet damper. The same elements as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  The first control system 29 of the reheater outlet damper control unit 19 obtains a deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the subtractor 21, and performs control calculation by the PID controller 22. Thus, the reheater outlet damper 15 is controlled. Further, the second control system 30 of the reheater outlet damper controller 19 calculates a deviation ΔH from the required opening degree H of the desuperheater spray water flow rate control valve 17 from the PID controller 25 by the subtractor 27. The opening degree of the reheater outlet damper 15 is adjusted by the PID controller 28 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero.

  The comparison selector 35 receives the output signal of the first control system 29 and the output signal of the second control system 30 and compares the output signal of the first control system 29 and the output signal of the second control system 30. . Then, the comparison selector 35 selects the larger one of the output of the first control system 29 and the output of the second control system 30 and outputs it to the reheater outlet damper 15.

  According to the sixth embodiment, when the output signal of the second control system 30 is large, the temperature reducer spray water flow rate control is operated, and the reheater outlet damper control and the reheater outlet damper control are performed. Since cooperative control is selected by the comparison selector 35, the temperature reduction effect by the reheater outlet damper 15 can be operated more quickly. Thereby, the opening degree of the desuperheater spray water flow rate adjustment valve 17 is suppressed, the flow rate of the spray water is reduced, and a decrease in boiler efficiency can be prevented.

(Seventh embodiment)
FIG. 7 is a configuration diagram of a boiler reheat steam temperature control device according to the seventh embodiment of the present invention. The seventh embodiment selects a larger one of the output of the first control system 29 and the output of the second control system 30 from the second embodiment shown in FIG. A comparison selector 35 that outputs to the outlet damper is provided, and the switching unit 32 is configured so that the superheater outlet temperature T1 is equal to or less than the value obtained by adding the bias value Tb to the reheater outlet temperature setting value Tr1 based on the comparison result of the comparator 31. When the output of the first control system 29 is selected, when the superheater outlet temperature T1 is not less than or equal to the reheater outlet temperature set value Tr1 plus the bias value Tb, the output of the comparison selector 35 is selected and restarted. This is output to the heater outlet damper 35. The same elements as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 7, the first control system 29 of the reheater outlet damper control unit 19 obtains a deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the subtractor 21, and sends it to the PID controller 22. The reheater outlet damper 15 is controlled by performing control calculation. Further, the second control system 30 of the reheater outlet damper controller 19 calculates a deviation ΔH from the required opening degree H of the desuperheater spray water flow rate control valve 17 from the PID controller 25 by the subtractor 27. The opening degree of the reheater outlet damper 15 is adjusted by the PID controller 28 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero.

  A subtractor 24 calculates a deviation (Tr1 + Tb−T1) between the value (Tr1 + Tb) obtained by adding the reheater outlet temperature set value Tr1 and the bias value Tb by the adder 23 and the superheater outlet temperature T1, and the deviation ΔT2 is calculated. Comparison is made by the comparator 31. When the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb), the output signal of the comparison selector 35 is selected.

  When the superheater outlet temperature T1 is larger than the added value (Tr1 + Tb), the temperature reducer spray water flow rate control is operated. For this reason, it becomes cooperative control with reheater exit damper control and desuperheater spray water flow rate control, and the required value of reheater exit damper control in that case is the output of the 1st control system 29, and the 2nd control system 30 Whichever is greater. On the other hand, when the superheater outlet temperature T1 is smaller than the added value (Tr1 + Tb), the temperature reducer spray water flow rate control does not operate. For this reason, the reheater outlet damper control by the first control system 29 is selected by the switch 32.

  According to the seventh embodiment, when the superheater outlet temperature T1 is smaller than the addition value (Tr1 + Tb), the reheater outlet damper control is performed by the first control system 29, and the superheater outlet temperature T1 is the addition value (Tr1 + Tb). ), The output signal of the reheater outlet damper control by the second control system 30 or the output signal of the reheater outlet damper control of the first control system 29 is selected by the comparison selector 35, whichever is larger. Therefore, since it is coordinated control with the desuperheater spray water flow rate control, it is possible to control the spray water flow rate to be minimum, and to prevent a decrease in boiler efficiency.

(Eighth embodiment)
FIG. 8 is a configuration diagram of a boiler reheat steam temperature control device according to the eighth embodiment of the present invention. The eighth embodiment is different from the second embodiment shown in FIG. 2 in that a switching determination unit 36 is provided instead of the comparator 31, and the switching unit 32 is based on the output of the switching determination unit 36. The output of the first control system 29 or the output of the second control system 30 is switched. The switching determination unit 36 calculates an increase in steam temperature from a temperature at which the superheater outlet temperature T1 is lower than a value obtained by adding the bias value Tb to the reheater outlet temperature set value Tr1, and based on the steam temperature increase change, The switching from the first control system 29 to the second control system 30 is determined. The same elements as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 8, the first control system 29 of the reheater outlet damper control unit 19 obtains a deviation ΔT1 between the reheater outlet temperature set value Tr1 and the superheater outlet temperature T1 by the subtractor 21, and sends it to the PID controller 22. The reheater outlet damper 15 is controlled by performing control calculation. Further, the second control system 30 of the reheater outlet damper controller 19 calculates a deviation ΔH from the required opening degree H of the desuperheater spray water flow rate control valve 17 from the PID controller 25 by the subtractor 27. The opening degree of the reheater outlet damper 15 is adjusted by the PID controller 28 so that the opening degree command of the desuperheater spray water flow rate adjustment valve 17 becomes zero.

  The switching determination unit 36 determines whether to switch from the first control system 29 to the second control system 30, and is a value obtained by adding the reheater outlet temperature set value Tr1 and the bias value Tb by the adder 23 (Tr1 + Tb ) And the superheater outlet temperature T1 (Tr1 + Tb−T1) is calculated by the subtractor 24, and the difference ΔT2 obtained as a result is differentiated by the differentiators 37 and 38. The comparator 39 compares the superheater outlet temperature T1 with a predetermined set temperature, and outputs a logical value “1” when the superheater outlet temperature T1 reaches a predetermined set temperature. The range-equipped comparators 40 and 41 permit the operation of the integrators 42 and 43 when the superheater outlet temperature T1 is within a predetermined temperature range.

  It is assumed that the superheater outlet temperature T1 is lower than the temperature set by the comparator 39. In this state, the output of the comparator 39 is a logical value “0”. In this state, if the superheater outlet temperature T1 rises rapidly and the raised superheater outlet temperature T1 is within the temperature range set by the comparator 40 with a range, the output value of the differentiator 37 is integrated by the integrator 42. And input to the comparator 44. The comparator 44 compares the integral value with a predetermined set value, and outputs a logical value “1” when the predetermined set value is exceeded.

  On the other hand, when the superheater outlet temperature T1 is lower than the temperature set by the comparator 39 and continues to rise rapidly from the low temperature to the temperature set by the comparator 39, the temperature range set by the comparator 41 with range is set. If so, the output value of the differentiator 38 is integrated by the integrator 43, and the comparator 45 compares the integrated value with a predetermined set value. When the predetermined set value is exceeded, the logical value “ 1 "is output.

  The selector 46 selects the comparator 44 when the superheater outlet temperature T1 rapidly increases, and selects the comparator 45 when the rapid increase continues to the temperature set by the comparator 39. The comparator 39 is selected when there is no rapid temperature rise up to the temperature set in.

  When the superheater outlet temperature T1 rises, the desuperheater spray water flow rate control is operated, so that the second control system 30 is selected by the selector 46 and the desuperheater spray water flow rate control unit 20 performs the desuperheater spray water flow rate control. Coordinated control between control and reheater outlet damper control is performed. Thereby, the opening degree of the desuperheater spray water flow rate control valve 17 is suppressed, the flow rate of the spray water is reduced, and a decrease in boiler efficiency can be prevented.

  In addition, when the superheater outlet temperature T1 is lower than the temperature set by the comparator 39 and there is no rapid temperature rise to the set temperature, the depressurizer spray water flow rate control does not operate, and therefore the selector 46 performs the first operation. The reheater outlet damper control by the control system 29 is selected, so that it is possible to prevent a decrease in boiler efficiency.

  According to the eighth embodiment, a function of switching cooperative control between reheater outlet damper control by the first control system 29, reheater outlet damper control by the second control system, and desuperheater spray water flow control. Therefore, it is possible to control the flow rate of the spray water to be minimum, and it is possible to prevent a decrease in boiler efficiency.

The block diagram of the boiler reheat steam temperature control apparatus concerning the 1st Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 2nd Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 3rd Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 4th Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 5th Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 6th Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 7th Embodiment of this invention. The block diagram of the boiler reheat steam temperature control apparatus concerning the 8th Embodiment of this invention. The block diagram of the reheat steam temperature control apparatus by a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Superheater, 12 ... Temperature reducer, 13 ... High pressure turbine, 14 ... Reheater, 15 ... Reheater exit damper, 16 ... Low pressure turbine, 17 ... Spray water flow control valve, 18 ... Boiler reheat steam temperature Control unit, 19 ... reheater outlet damper control unit, 20 ... desuperheater spray water flow rate control unit, 21 ... subtractor, 22 ... PID controller, 23 ... adder, 24 ... subtractor, 25 ... PID controller , 26 ... Opening limiter, 27 ... Subtractor, 28 ... PID controller, 29 ... First control system, 30 ... Second control system, 31 ... Comparator, 32 ... Switch, 33 ... Gate circuit, 34 ... Function generator, 35... Comparison selector, 36.

Claims (9)

  Based on the deviation between the boiler superheater outlet temperature and the reheater outlet temperature setpoint, the reheater outlet damper and desuperheater spray water flow control valve are used to control the temperature of the boiler reheater. In the boiler reheat steam temperature control device to be performed, a desuperheater spray water flow rate control unit that controls the reheater outlet steam temperature to a set value by adjusting the desuperheater spray water flow rate by the desuperheater spray water flow rate control valve And a reheater outlet that controls the reheater outlet steam temperature to a set value by adjusting the opening of the reheater outlet damper so that the opening command of the desuperheater spray water flow control valve becomes zero A boiler reheat steam temperature control device comprising a damper control unit.   Based on the deviation between the boiler superheater outlet temperature and the reheater outlet temperature setpoint, the reheater outlet damper and desuperheater spray water flow control valve are used to control the temperature of the boiler reheater. In the boiler reheat steam temperature control device to be performed, a desuperheater spray water flow rate control unit that controls the reheater outlet steam temperature to a set value by adjusting the desuperheater spray water flow rate by the desuperheater spray water flow rate control valve And a reheater outlet damper control unit that controls the reheater outlet steam temperature to a set value by adjusting the opening of the reheater outlet damper, and the reheater outlet damper control unit includes a superheater. The first control system for adjusting the opening degree of the reheater outlet damper so that the outlet temperature becomes the reheater outlet temperature set value, and the opening degree command of the desuperheater spray water flow rate control valve to be zero A second control system for adjusting the opening degree of the reheater outlet damper, and a superheater outlet; A comparator for determining whether the degree is equal to or less than a value obtained by adding a bias value to the reheater outlet temperature set value, and if the comparison result of the comparator is as follows, the output of the first control system is selected and is not less than A boiler reheat steam temperature control device comprising a switch for selecting the output of the second control system.   3. The boiler reheat steam temperature control device according to claim 2, wherein switching between the first control system and the second control system can be manually selected.   The boiler reheat steam temperature control device according to claim 1, wherein the gain of the reheater outlet damper control unit is variable depending on a deviation between a reheater outlet temperature set value and a superheater outlet temperature.   The gain of the second control system of the reheater outlet damper control unit is variable depending on a deviation between an addition value obtained by adding a bias value to a reheater outlet temperature setting value and a superheater outlet temperature. The boiler reheat steam temperature control device according to 2.   In place of the comparator and the switch, a comparison selector that selects the larger one of the output of the first control system and the output of the second control system and outputs it to the reheater outlet damper is provided. The boiler reheat steam temperature control device according to claim 2. A comparison selector is provided for selecting a larger one of the output of the first control system and the output of the second control system and outputting the selected one to the reheater outlet damper. Therefore, when the superheater outlet temperature is equal to or less than the value obtained by adding the bias value to the reheater outlet temperature set value, the output of the first control system is selected, and the superheater outlet temperature is set to the reheater outlet temperature set value 3. The boiler reheat steam temperature control device according to claim 2, wherein the output of the comparison selector is selected and output to the reheater outlet damper when the value is not equal to or less than the value obtained by adding the value of 1.   The reheater outlet damper control unit calculates, in place of the comparator, a rise in steam temperature from a temperature at which the superheater outlet temperature is lower than a value obtained by adding a bias value to the reheater outlet temperature set value, A switching determination unit configured to determine switching from the first control system to the second control system based on a change in steam temperature, and the switching unit outputs or outputs the first control system based on the output of the switching determination unit; The boiler reheat steam temperature control device according to claim 2, wherein the output of the two control system is switched.   Based on the deviation between the boiler superheater outlet temperature and the reheater outlet temperature setpoint, the reheater outlet damper and desuperheater spray water flow control valve are used to control the temperature of the boiler reheater. In the boiler reheat steam temperature control method to be performed, the desuperheater spray water flow rate is adjusted by the desuperheater spray water flow rate control valve, and the reheater outlet steam temperature is controlled to the set value, and the desuperheater spray water flow rate is controlled. Reheater outlet damper temperature is controlled to a set value by adjusting the opening degree of the reheater outlet damper so that the opening degree command of the desuperheater spray water flow control valve is zero. The boiler reheat steam temperature control method characterized by this.

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