JP4216693B2 - Vacuum degree control method and apparatus for air-cooled steam condensing device - Google Patents

Description

  The present invention relates to a vacuum degree control method and apparatus for an air-cooled steam condensing device provided in a steam turbine plant.

  Conventionally, in an air-cooled steam condensing device that condenses exhaust steam from a turbine or the like, a method as shown in FIG. 10 is known to control the condensate temperature and condensate pressure (for example, Patent Document 1). ).

  In this control method, as shown in the figure, the steam pressure in the condensing device 21 into which steam flows from the boiler through the steam introduction pipe 20 is detected by the pressure detector 22, and the deviation between the gas phase pressure P1 and the pressure set value SVP is detected. The condensate temperature and the condensate pressure are controlled by calculating the PID with the gas phase pressure controller 23 and controlling the pressure control symmetrical device (axial fan) 24.

  Further, the liquid phase pressure of the condensate flowing out from the condenser 21 to the condensate tank through the condensate introduction pipe 25 is detected by the liquid phase pressure detector 26, and the difference between the detected liquid phase pressure P2 and the gas phase pressure P1 is detected. The deviation between the pressure and the water level set value SVL is PID-calculated by the water level controller 27 and the control valve 28 provided in the condensate introduction pipe 25 is controlled to control the water level constant.

  In this air-cooled steam condensing device, usually, a plurality of fans (axial blowers) 24 are operated in parallel, and the number of operating units needs to be increased or decreased according to the load demand (heat load of the steam condensing device).

  For this reason, for example, when a predetermined number of axial fans are in operation and there is a request for additional operation of one or more due to load fluctuations, one or more specific axial fans that match the required number Additional operation. In addition, when there is a request for stopping one or more units, the axial blower that has been previously operated is stopped.

  However, in such a control method, there has been a problem that the operation time becomes longer for a device that starts operation first, and conversely, the operation time becomes shorter for a device that is operated last (additional operation).

As a control method for solving this problem, in a system including an operation counter and a stop counter for storing a number assigned to the axially blower that has been last operated and stopped, a predetermined number of axial flow fans When starting or stopping the operation of the device, the operation is started or stopped from the device numbered by adding 1 to the number stored in the operation counter or the stop counter. There is one in which these devices are operated uniformly (for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-185458 JP 2000-283051 A

  However, since the control as described above is intended to make the operation load of the axial flow fan uniform, depending on the required heat load of the steam condensing device, any axial flow fan is frequently started according to its priority, There is no change that an event occurs in which the stoppage is repeated and the axial blower starts or stops constantly is not stable.

  The present invention has been made in view of the above circumstances, and by applying a relatively simple calculation processing method when performing PID calculation of the difference between the control request value and the detection value, any required steam condensing apparatus is required. It is an object of the present invention to provide a method and an apparatus for controlling the degree of vacuum of an air-cooled condensing device that can prevent repeated operation and stop of the axial flow fan even under a thermal load.

  In order to achieve the above object, the present invention controls the degree of vacuum of the air-cooled condensing device by the following method and apparatus.

  The invention corresponding to claim 1 detects the degree of vacuum of an air-cooled steam condensing device provided in a steam turbine plant, and calculates a cooling air volume control value based on this degree of vacuum and a preset target degree of vacuum. Then, based on the calculation result, the high-priority axial flow fan is started or stopped from among the plurality of axial flow fans, thereby controlling the cooling air flow rate and controlling the vacuum degree of the air-cooled steam condensing device. In the vacuum degree control method, after a predetermined number of axial flow fans are sequentially operated from among a plurality of axial flow fans, the actual vacuum degree detected by the air-cooled steam condensing device is set with respect to the target vacuum degree. When either the upper limit value or the lower limit value is exceeded, the difference between the actual vacuum degree and the upper limit value or the lower limit value is integrated, and the integrated value is compared with the separately set operation set value. Only when exceeds the operating set value To add up or add stop the axial-flow fan of.

  The invention corresponding to claim 2 is the method for controlling an air-cooled steam condensing device of the invention corresponding to claim 1, wherein the change in the actual vacuum degree is performed only when the integral value exceeds the separately set operation set value. And evaluate whether the actual vacuum is approaching or far away from the target vacuum, and the next axial flow fan is additionally operated or added only when it is far away. Stop.

  According to a third aspect of the present invention, in the vacuum degree control method for an air-cooled steam condensate device according to the first or second aspect of the present invention, the integral value is an operation set value for each preset time. If the integral value does not exceed the operation set value, the calculation of the integral value is continued.

  According to a fourth aspect of the present invention, in the vacuum degree control method for an air-cooled steam condensate device according to the first or second aspect of the present invention, the integral value is an operating set value for each preset time. When the integrated value does not exceed the operation set value, the integrated value obtained by the calculation is cleared.

  The invention corresponding to claim 5 is the vacuum control method for the air-cooled steam condensing device of the invention corresponding to claim 1 or claim 2, wherein the upper limit value and the lower limit value set for the target vacuum degree are set. In addition, a direct operation upper limit value and a direct stop lower limit value are further set, and when the actual vacuum exceeds the direct stop upper limit value or the direct operation lower limit value, the axial flow fan having a higher priority is immediately stopped or started.

The invention corresponding to claim 6 detects the degree of vacuum of the air-cooled steam condensing device provided in the steam turbine plant, and calculates the cooling air flow rate control value based on this degree of vacuum and a preset target degree of vacuum. Then, based on the calculation result, the high-priority axial flow fan is started or stopped from among the plurality of axial flow fans, thereby controlling the cooling air flow rate and controlling the vacuum degree of the air-cooled steam condensing device. In the vacuum degree control device, the first degree is determined to determine whether or not the actual vacuum degree detected by the air-cooled steam condensing device is within a range between an upper limit value and a lower limit value set in advance with respect to the target vacuum degree. If the actual vacuum degree is not within the range between the upper limit value and the lower limit value by the determining means, and the first determining means, the calculating means for integrating the difference between the actual vacuum degree and the upper limit value or the lower limit value; was integral value and the axis that is set separately Comparing the blower operation setting value, a second determination means for determining the necessity of additional working or additional stop of axial-flow fan, and requires additional operational or additional stop of the axial flow fan by the second determination means When the determination is made, output means for sending an additional operation or additional stop command to the axial blower having a high priority is provided.

The invention corresponding to claim 7 is the vacuum control device for an air-cooled steam condensing device of the invention corresponding to claim 6, wherein the calculation means has a timer for sending a preset time operation pulse signal, this timer to determine whether the integration value by the integral calculated by the second determination means for each reach time settings from being started exceeds the axial flow fan operation setting value.

  According to the present invention, when a difference between the control required value and the detected value is PID-calculated, a relatively simple calculation processing method is applied, so that this axial blower can be used at any required heat load of any steam condensing device. Can be prevented from being repeatedly operated and stopped.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing an example of the entire air-cooled steam condensing device of the present invention.

  As shown in FIG. 1, the steam sent from the steam generator 1 to the steam turbine 3 through the main steam pipe 2 flows to the upper header 6 through the exhaust communication pipe 5 after completing the work of rotating the generator 4. , Led to a plurality of steam condenser pipe bundles 7.

  These steam condensing device tube bundles 7 are incorporated in a roof-type structure, and air as a cooling medium is directed toward the tube bundle 7 by a plurality of axial flow fans 8 respectively attached to a gantry (not shown) installed below the steam condensing device. It is supposed to be sent.

  The steam flowing through each of the tube bundles 7 is condensed with the latent heat removed by the cooling air sent from the axial blower 8, flows into the lower header 9 as water, and then passes through the collecting pipe 10 to the condensate tank. 11 leads to. The condensate collected in the condensate tank 11 is sent again to the steam generator 1 by the condensate pump 12.

  On the other hand, a vacuum degree detector 13 is provided in the exhaust communication pipe 5, and a vacuum degree detection signal detected by the vacuum degree detector 13 is input to the axial flow fan operation control device 15 via the amplifier 14. This axial flow fan operation control device 15 calculates the cooling air flow rate control value based on the vacuum level detection signal and the output signal of the vacuum level setter 16 that sets the vacuum level to be controlled. Based on the above, by giving a start or stop signal to the axial blower 8 having a high priority, the flow rate of the cooling air is controlled, and the degree of vacuum of the steam condensing device is controlled.

  Here, the vacuum degree setting device 16 sets the target vacuum degree Pst, sets a certain coefficient for the set value, sets the upper limit value PL of the vacuum degree, and the lower limit value PH of the vacuum degree, and further the axial flow The blower operation set value SZ is set. In addition, since the degree of vacuum is a value obtained by subtracting the pressure in the condensing apparatus from 1 atm, when considering the actual pressure in the condensing apparatus, the higher the degree of vacuum, the lower the pressure, and conversely, the lower the degree of vacuum. It shows that the pressure increases. In the following description, the degree of vacuum is simply described unless otherwise specified.

The axial flow fan operation control device 15 determines whether the actual vacuum degree P0 detected by the vacuum degree detector 13 is within the range of the upper limit value PL and the lower limit value PH with respect to the target vacuum degree Pst. And a timer for starting and transmitting an operation pulse signal when the actual vacuum degree P0 is determined not to be within the range of the upper and lower limit values by the first determining means. Computation means for integrating the difference between the actual vacuum degree and the upper limit value or lower limit value for each set time, and the integral value S obtained by this computation means and the axial flow fan operation set value SZ are compared, and the axial flow The second determining means for determining whether or not the additional operation or additional stop of the blower is necessary, and if the second determination means determines that the additional operation or additional stop of the axial flow fan is necessary, the axial flow having a higher priority. Additional operation or additional stop for the blower And an output means for sending a command.

  Next, the operation of the vacuum control device of the air-cooled steam condensing device configured as described above will be described with reference to FIGS.

  FIG. 2 is a graph showing a first embodiment for explaining a vacuum degree control method for an air-cooled steam condensing device according to the present invention. In the graph of FIG. 2, the vertical axis represents pressure, and the upper side indicates a higher pressure state. That is, when considering the degree of vacuum, the lower part represents a higher degree of vacuum.

  When the target vacuum degree Pst is set as shown in FIG. 2, the upper limit value PL of the vacuum degree and the lower limit value PH of the vacuum degree are set by providing a certain coefficient for the set value. Here, as an example, a pressure 1.1 times the pressure corresponding to the target vacuum degree Pst is a lower limit value PH of the vacuum degree, and a pressure 0.9 times the pressure corresponding to the target vacuum degree Pst is an upper limit value PL of the vacuum degree. However, it can be changed depending on the installation area of the air-cooled steam condensing device and the specifications of the applicable axial flow fan. Furthermore, an axial flow fan operation set value SZ (here, set as 1 MPa · s as an example) is provided.

  Further, as described above, in order to avoid an extreme continuous operation, an operation command pulse signal output time (60 seconds as an example here) is set in the timer.

  First, the process at the time of plant load increase is demonstrated, referring the flowchart shown in FIG.

  It is assumed that the actual vacuum level detected by the vacuum level detector 13 is converted to a level required for signal processing by the amplifier 14 and the output signal is input to the axial flow fan operation control device 15. At this time, if the actual vacuum degree P0 is between the lower limit PH and the upper limit PL, the axial flow fans other than the axial flow fan that is in operation at that time will not be additionally operated or stopped.

  In such a state, when the plant load is reduced and the target vacuum degree Pst is to be maintained, when the vacuum degree is lowered due to a reduction in the thermal load of the steam condensing device, the integral value S obtained by the integral calculation means is reset ( After ST1), it is determined by the first determination means that the actual vacuum degree P0 has exceeded the upper limit PL (ST2).

  Simultaneously with this determination, the timer T is started (ST3), and the difference (P0) between the actual vacuum degree P0 and the upper limit set value PL is calculated by the computing means on the condition that the actual vacuum degree P0 exceeds the upper limit value PL (ST4). -PL) is started (ST5).

  Then, every time the set time Tlim of the start command pulse signal interval (in this case, 60 seconds) is reached (ST6) after the timer is started (ST6), the integration value S by the integration calculation is changed to the axis by the second determination means. It is determined whether or not the flow blower operation set value SZ (1 MPa · s) is exceeded (ST7). If S> SZ, one axial flow blower is additionally stopped (ST8).

  On the other hand, if S> SZ is not satisfied, the process returns to ST4 again to determine whether or not the actual vacuum degree P0 exceeds the upper limit value PL. If P0> PL, the integration operation is continued, and P0> PL Otherwise, the process returns to ST1 to reset the integral value S.

That is, if the integral value S obtained by the integral calculation does not reach the axial flow fan operation set value SZ within the start command pulse signal interval (60 seconds), the next axial flow fan is not additionally stopped and the current number of operating units is set. While continuing to integrate the difference between the actual vacuum degree P0 and the upper limit set value PL, the integrated value S is compared with the axial flow fan operating set value SZ every time a subsequent start command pulse signal is received. Then, it is determined whether or not the axial flow fan needs to be additionally stopped.

  In this way, the axial blower continues to stop in descending order of priority until the actual vacuum level falls below the upper limit value PL of the set value Pst, the cooling capacity of the steam condensing device falls below the thermal load, and the actual vacuum level P0 is set to the upper limit. When the value PL falls below the value PL, the integral value S and the timer T are reset, and S = 0 and T = 0.

  The above is the operation when the plant load decreases and the actual vacuum level exceeds the upper limit PL of the set value Pst. On the contrary, the actual vacuum level decreases due to the increase in the thermal load of the steam condensing device. When the actual vacuum degree P0 is below the lower limit PH of the set value Pst, the flowchart shown in FIG. 4 is obtained.

  When the degree of vacuum decreases due to an increase in the heat load of the steam condensing device, the integrated value S obtained by the integral calculating means is reset (ST11), and then the actual degree of vacuum P0 falls below the lower limit PH by the first determining means. (ST12).

  At the same time as this determination, the timer T is started (ST13), and the condition (ST14) is that the actual vacuum degree P0 is below the lower limit PH, and the difference between the actual vacuum degree P0 and the lower limit set value PH (PH -P0) is started (ST15).

  Then, every time the set time Tlim of the start command pulse signal interval (here, 60 seconds) is reached (ST16) after the timer is started (ST16), the integral value S obtained by the integration calculation is converted to the axis by the second determination means. It is determined whether or not the flow blower operation set value SZ (1 MPa · s) is exceeded (ST17). If S> SZ, one axial flow blower is additionally operated (ST18).

  On the other hand, if S> SZ is not satisfied, the process returns to ST14 again to determine whether or not the actual vacuum degree P0 is lower than the lower limit value PH. If P0 <PH, the integration operation is continued, and P0 <PH Otherwise, the process returns to ST11 and the integral value S is reset.

That is, if the integral value S obtained by the integral calculation does not reach the axial blower operation set value SZ within the start command pulse signal interval (60 seconds), the next axial flow fan is not additionally operated and the current number of operating units is set. While continuing to integrate the difference between the actual vacuum degree P0 and the lower limit set value PL, the integrated value S is compared with the axial flow fan operating set value SZ every time a subsequent start command pulse signal is received. The necessity of additional operation of the axial blower is then determined.

When it is determined that the integral value S has exceeded the axial flow fan operation set value SZ within the start command pulse signal interval (60 seconds), the axial flow blower having a high priority is reached when the axial flow fan operation set value SZ is exceeded. Start up. If the integral value does not reach the axial flow fan operation set value SZ within the start command pulse signal interval (60 seconds), the next axial flow fan is not started and the current number of operating units is maintained. The integration means continues to integrate the difference between P0 and the lower limit PH, and the integral value S is compared with the axial flow fan operation set value SZ every time a subsequent start command pulse signal is received. Then, it is determined whether or not it is necessary to start an axial blower having a high start priority.

  Thus, the axial blower continues to start until the actual vacuum degree P0 exceeds the lower limit value PH of the set value Pst, the cooling capacity of the steam condensing device exceeds the heat load, and the actual vacuum degree P0 exceeds the lower limit set value PH. At this time, the integral value S and the timer T are reset, and S = 0 and T = 0.

  According to the present embodiment, as described above, since it is possible to have a control band having a constant width with respect to one vacuum degree control set value, the axial blower is frequently operated and stopped. A stable required degree of vacuum can be obtained without repeatedly applying a load.

In addition, since the integral value S after the timer is started is determined every set time Tlim, the timing to perform additional stop or additional start of the axial fan can be adjusted by the set value of Tlim, and the operating environment ( It can be operated according to the time constant of fluctuations in outside air temperature, plant output, etc.

  FIG. 5 is a graph showing a second embodiment for explaining the vacuum control method of the air-cooled steam condensing device according to the present invention.

  In the second embodiment, the slope of the degree-of-vacuum change curve at the time of calculating the integral value in the first embodiment is calculated. The same components as those in the first embodiment are denoted by the same reference numerals, A duplicate description is omitted.

As an operation of this embodiment, every time an operation command pulse signal is received, the integral value S and the axial flow fan operation set value SZ are compared, the slope of the vacuum degree change curve is calculated, and the actual vacuum degree P0 is the upper limit. When the value PL is exceeded, when the slope of the degree-of-vacuum change curve is positive (when the slope changes to the right in FIG. 5), the next axial blower is additionally stopped. Conversely, when the slope of the vacuum degree change curve is negative (when it rises to the right in FIG. 5), no additional stop is performed.

  FIG. 6 is a flowchart for processing whether or not the plant load is reduced and the actual vacuum level exceeds the upper limit value PL of the set value Pst. The same steps as those in FIG. Here are the differences.

  In FIG. 6, it is determined whether or not the integral value S obtained by the integral calculation exceeds the axial flow fan operation set value SZ (1 MPa · s) (ST7). If S> SZ, the slope dp0 of the vacuum degree change curve is determined. / dt is obtained to determine whether the slope dp0 / dt of the change curve of the degree of vacuum is positive (ST9). When dp0 / dt> 0, one additional axial fan is stopped and dp0 / If dt> 0, the process returns to ST4 to determine whether or not the actual degree of vacuum P0 exceeds the upper limit value PL. Here, if P0> PL, the integration operation is continued. Return to reset the integral value S.

On the other hand, when the actual vacuum level decreases due to an increase in the heat load of the steam condensing device and the actual vacuum level P0 is below the lower limit PH of the set value Pst, the slope of the vacuum level change curve is positive. axis when the start of the next axial blower is not performed in (when the downward-sloping in FIG. 5), and when the slope degree of vacuum change curve is negative (when soaring in Figure 5) of to implement the start-up of the flow blower.

  FIG. 7 is a flowchart in this case. The same steps as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted. Differences will be described here.

  In FIG. 7, it is determined whether or not the integral value S obtained by the integral calculation exceeds the axial flow fan operating set value SZ (1 MPa · s) (ST17). If S> SZ, the slope dp0 of the vacuum degree change curve is determined. / dt is determined to determine whether the slope dp0 / dt of the curve for changing the degree of vacuum is negative (ST19). When dp0 / dt <0, one additional axial fan is operated, and dp0 / dt If <0, return to ST14 to determine whether or not the actual degree of vacuum P0 exceeds the lower limit PH. If P0 <PH, continue the integration operation. If P0 <PH, return to ST11. To reset the integral value S.

  According to the present embodiment, since the actual vacuum degree P0 is constantly monitored as to whether it is approaching or far from the set value Pst, the required vacuum is more stable than that of the first embodiment. You can get the degree faster.

  FIG. 8 is a flowchart showing a third embodiment for explaining the vacuum degree control method of the air-cooled steam condensing device according to the present invention.

  In the first embodiment and the second embodiment described above, it is determined whether or not the integral value S after starting the timer exceeds the axial flow fan operation set value SZ every set time Tlim. However, in the third embodiment, it is determined whether or not the integral value S after starting the timer exceeds the axial blower operation set value SZ every set time Tlim. Sometimes the integral value is reset and the determination is made again.

  FIG. 8 shows such a determination process in response to a decrease in plant load. The difference from FIG. 3 is that T> Tlim is determined in step ST6 ′, and S> Sz is not determined in step ST7. Returning to step ST1, the integration value S is reset and a series of processing is executed.

  By performing such processing, additional stop is not performed even when the steam pressure of the exhaust communication pipe is stable in the vicinity of the threshold, so the number of additional stop of the axial blower is reduced, and the axial flow blower is reduced. The number of operating units can be stabilized.

  The flow chart shown in FIG. 8 is a case where the actual vacuum degree P0 and the upper limit set value PL are compared to determine whether or not the axial blower is additionally stopped. As shown in FIG. Even when it is determined whether or not the axial flow fan is additionally operated by comparing with the set value PH, the same determination processing as in FIG. 8 can be performed. Further, as shown in the flowcharts of FIGS. 6 and 7 shown in the second embodiment, the actual vacuum degree P0 is approaching or far from the set value Pst depending on the slope dp0 / dt of the vacuum degree change curve. Even when it is determined whether or not there is a determination process, the same determination process as in FIG. 8 can be performed.

  FIG. 9 is a graph showing a fourth embodiment for explaining a vacuum control method of the air-cooled steam condensing device according to the present invention.

  In the fourth embodiment, a direct operation lower limit PHH and a direct stop upper limit PLL are further provided in the first embodiment (here, a vacuum corresponding to a pressure 1.5 times the target value Pst as an example) The vacuum degree corresponding to 0.5 times the pressure corresponding to the target operation value Pst and the direct operation lower limit value PHH is directly set as the stop upper limit value PLL. The same reference numerals are given, and duplicate descriptions are omitted.

  By providing the direct operation lower limit PHH and the direct stop upper limit PLL, the vacuum degree control according to the first embodiment is performed in a situation where the thermal load of the steam condensing device suddenly increases, such as turbine bypass operation. Since it is difficult to achieve recovery to a control band having a certain width with respect to the vacuum degree control set value, if the direct operation lower limit PHH and the direct stop upper limit PLL are exceeded, the priority is immediately higher. By starting or stopping the axial blower, early recovery to the target vacuum level can be achieved.

The block diagram which shows an example of the whole air-cooled steam condensate apparatus to which this invention is applied. The graph which shows 1st Embodiment for demonstrating the vacuum control method of the air-cooling type steam condensing apparatus by this invention. The flowchart which shows the process at the time of plant load rise in the same embodiment. In the same embodiment, the flowchart which shows a process in case an actual vacuum degree raises by the reduction | decrease of a thermal load, and the actual vacuum degree exceeds the upper limit of a setting value. The graph which shows 2nd Embodiment for demonstrating the vacuum control method of the air-cooling type steam condensing apparatus by this invention. The flowchart which shows the determination processing whether the actual vacuum degree is less than the lower limit of a target setting value at the time of plant load rise in the same embodiment. The flowchart which shows the determination processing whether the actual vacuum degree is over the upper limit of a target setting value at the time of plant load reduction | decrease in the same embodiment. The flowchart which shows 3rd Embodiment for demonstrating the vacuum degree control method of the air-cooling type steam condensing apparatus by this invention. The graph which shows 4th Embodiment for demonstrating the vacuum control method of the air-cooling type steam condensing apparatus by this invention. The block diagram which shows an example of the whole conventional air-cooling type steam condensing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steam generator, 2 ... Main steam pipe, 3 ... Steam turbine, 4 ... Generator, 5 ... Exhaust communication pipe, 6 ... Upper header, 7 ... Steam condensing apparatus pipe bundle, 8 ... Axial flow fan, 9 ... Lower part Header 10, collecting pipe 11, condensate tank 12, condensate pump 13, vacuum detector 14, amplifier 15, axial blower operation controller, 16 vacuum setting device

Claims (7)

The degree of vacuum of the air-cooled steam condensing device installed in the steam turbine plant is detected, the cooling air volume control value is calculated based on this degree of vacuum and a preset target degree of vacuum, and a plurality of values are calculated based on the calculation result. In the vacuum degree control method for controlling the vacuum degree of the air-cooled steam condensing device by controlling the flow rate of the cooling air by starting or stopping the axial flow fan having a high priority from the axial flow fans of
After sequentially operating a predetermined number of axial fans from among a plurality of axial fans, the actual vacuum detected by the air-cooled steam condensing device is an upper limit value and a lower limit value set for the target vacuum degree. If any of the above is exceeded, the difference between the actual vacuum degree and the upper limit value or the lower limit value is integrated, and the integral value is compared with an operation set value set separately, and the integrated value exceeds the operation set value. A vacuum degree control method for an air-cooled steam condensing device, characterized in that only when the next axial blower is additionally operated or additionally stopped.   In the vacuum degree control method of the air-cooled steam condensate device according to claim 1, the inclination of the change in the actual vacuum degree is evaluated only when the integral value exceeds the separately set operation set value. An air-cooled steam characterized by determining whether the target vacuum degree is approaching or distant, and additionally operating or stopping the next axial blower only when the target vacuum is approaching Vacuum degree control method for condensing device.   3. The method for controlling the degree of vacuum of an air-cooled steam condensing device according to claim 1 or 2, wherein the integrated value is compared with an operating set value every time a preset time elapses, and the integrated value exceeds the operating set value. A vacuum degree control method for an air-cooled steam condensing device, characterized in that the calculation of the integral value is continued when there is not.   3. The method for controlling the degree of vacuum of an air-cooled steam condensing device according to claim 1 or 2, wherein the integrated value is compared with an operating set value every time a preset time elapses, and the integrated value exceeds the operating set value. When there is not, the integrated value calculated | required by the said calculation is cleared, The vacuum degree control method of the air-cooling type steam condensate apparatus characterized by the above-mentioned.   The vacuum control method for an air-cooled steam condensing device according to claim 1 or 2, wherein, in addition to the upper limit and lower limit set for the target vacuum, a direct operation upper limit and a direct stop lower limit When the actual vacuum degree exceeds the direct stop upper limit value or the direct operation lower limit value, the high-priority axial flow blower is immediately stopped or started. Control method. The degree of vacuum of the air-cooled steam condensing device installed in the steam turbine plant is detected, the cooling air volume control value is calculated based on this degree of vacuum and a preset target degree of vacuum, and a plurality of values are calculated based on the calculation result. In the vacuum degree control device for controlling the degree of vacuum of the air-cooled steam condensing device by controlling the flow rate of the cooling air by starting or stopping the axial flow fan having a high priority among the axial flow fans of
First determination means for determining whether the actual vacuum detected by the air-cooled steam condensing device is within a range between an upper limit value and a lower limit value set in advance with respect to the target vacuum degree; If the actual vacuum degree is not within the range of the upper and lower limit values by the determining means, the calculating means for integrating the difference between the actual vacuum degree and the upper limit value or the lower limit value, and the integral value obtained by this calculating means separately Compared with the set axial flow fan operation set value, the second determination means for determining whether additional operation or additional stop of the axial flow fan is necessary, and additional operation of the axial flow fan by the second determination means or Vacuum degree control of an air-cooled steam condensing device, comprising an output means for sending an additional operation or additional stop command to an axial flow fan having a high priority when it is determined that an additional stop is necessary apparatus. 7. The vacuum control apparatus for an air-cooled steam condensing device according to claim 6, wherein the calculating means has a timer for sending a preset time operation pulse signal, and each time the set time is reached after the timer is started. A vacuum degree control device for an air-cooled steam condensing device , wherein the second determination means determines whether or not an integrated value by an integral calculation exceeds an axial flow fan operation set value .

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