JP4832049B2 - Control device and control method for condensate demineralizer - Google Patents

Description

  The present invention relates to a control device and control method for a condensate demineralizer, and more specifically, a control device for a condensate demineralizer that is used in a thermal power plant or the like and processes water supplied from a condenser. And a control method.

  Thermal power plants change the thermal energy of fuels such as coal, oil, and gas into mechanical energy and further into electrical energy.

  As shown in FIG. 1, for example, in a thermal power plant using coal as fuel, coal is combusted in a boiler 15 to change feed water 10 into steam 11 and send it to a high-pressure turbine 17, an intermediate-pressure turbine 18, and a low-pressure turbine 19. Yes. The thermal energy of the steam is converted into mechanical energy by these turbines, rotates the turbine blades, rotates the generators 20 and 21 connected to the respective turbines, and generates electrical energy.

  The steam exhausted from the turbines 17, 18, 19 is sent to the condenser 5. The condenser 5 is a device that cools and condenses the exhaust (steam) of the turbine to create a vacuum and collect it as condensate. That is, steam from the turbine and seawater as cooling water are taken in, non-contact heat exchange is performed, the steam is cooled and recovered as condensate (feed water) 10, and sent again to the boiler 15 by the feed water pump 22.

  A condensate demineralizer (commonly referred to as “demine”) (not shown in FIG. 1) (not shown in FIG. 1) is disposed in the middle of a water supply pipe through which the water supply 10 is sent from the condenser 5 to the boiler 15. Purifies the water supplied to The condensate demineralizer includes an ion exchange resin and increases the purity of the feed water by allowing the feed water to pass through. Therefore, if a certain amount of water is passed through, the ion exchange resin becomes dirty and does not perform the purification action, so it is necessary to regenerate or replace it.

Large-scale thermal power plants also require a large amount of water purification, so in general, multiple condensate demineralizers (also called “condensate demineralizers” and “towers”) are connected in parallel to meet the required amount. It corresponds. In addition, by connecting a plurality of condensate demineralizers in parallel, only a dirty condensate demineralizer is stopped and taken out for regeneration or replacement while operating a thermal power plant.
Japanese Patent Laid-Open No. 6-43289 “Water Supply System for Power Plant” (Publication Date: February 18, 1994) The invention disclosed in Japanese Patent Laid-Open No. 6-43289 is a condensate demineralizer even when the condensate pump is stopped. This is a technique for stopping the low-pressure drain pump when the condensate pump is stopped in order to prevent the resin from deteriorating while maintaining this function, and is not related to the present invention.

  Here, to stop the dirty condensate demineralizer while operating the thermal power plant, balance the amount of condensate water (load) and the amount of water flowable (per condensate demineralizer). It is necessary to stop while monitoring. When a situation occurs where the load exceeds the allowable flow rate, the inlet pressure of the condensate booster pump at the rear stage of the condensate demineralizer decreases, and the condensate booster pump (multiple units connected in parallel with the safety device working) Some units (see 37 in FIG. 2) stop (pump trip), and there is a possibility that a runback accident (forcibly returning the water supply to the condenser) may occur. Therefore, monitoring of the load and the amount of water that can be passed is extremely important.

On the other hand, as means for controlling the operation of a large-scale thermal power plant, lower-order control means are hierarchically constructed from higher-order control means and are responsible for operation control as a whole. For example, in the Misumi thermal power plant owned by the applicant, although not shown, during the power plant start / stop process, CPTR (APS (start / stop program) of the unit computer) is passed through TSQ (turbine sequence controller). The start / stop is output to the local sequencer (SQ for the condensate demineralizer), and the local sequencer that receives the signal actually drives the valve etc. according to the start / stop program of the condensate demineralizer to The tower is moved to the water or stopped state.
When the power plant is in normal operation, the APS program of the unit computer is not controlled, so the CRT (operator control panel) is used when the operator determines that the water flow through each tower of the condensate demineralizer can be confirmed and stopped. When stop / start is output from, a stop / start command is output to the local sequencer via TSQ. In other words, CPTR issues a command to start and stop the condensate demineralizer during the power plant startup / shutdown process, and an operator issues a command to start and stop the power plant when it enters a normal operating state. All start / stop commands output from CPTR or CRT are output to the local sequencer through TSQ (input signal passes through the opposite line).
In addition, when the power plant is in a normal operation state, the start / stop protection interlock for the condensate demineralizer is only the interlock programmed in the local sequencer. The condition for canceling the stop command is “2 towers”. Only the following water flow conditions. This is an interlock that does not actually function because the balance between the condensate flow rate (load) and the condensate demineralizer flow rate cannot be maintained if the power plant becomes less than two towers in normal operation. .

  Accordingly, it has been desired to develop a control device and a control method for a condensate demineralizer that monitors and controls the load of the condensate demineralizer and the amount of water that can be passed even when a plurality of towers are stopped.

  The developed condensate demineralizer control device and control method should also be a system that can be realized without significant changes to the existing hierarchically constructed thermal power plant control means. It was rare.

  Accordingly, it is an object of the present invention to provide a novel condensate demineralizer control apparatus.

  Furthermore, an object of this invention is to provide the control method of a novel condensate demineralizer.

  Furthermore, an object of the present invention is to provide a novel condensate demineralizer control device that can be realized without significant changes to the control means of existing thermal power plants.

  Furthermore, an object of the present invention is to provide a novel condensate demineralizer control method that can be realized without significant changes to the control means of existing thermal power plants.

  In view of the above object, a condensate demineralizer control device according to the present invention is a condensate demineralizer control device connected in parallel to a plurality of units for purifying the condensate of a power plant. When stopping one of the stands, there is provided means for disabling the stop if the water flow rate of each condensate demineralizer after the stop exceeds a predetermined allowable value.

  Furthermore, the condensate demineralizer control device according to the present invention is a condensate demineralizer control device connected in parallel to a plurality of units N for purifying the condensate of the power plant. Means for calculating the current total condensate flow rate W when stopping one of the units, means for calculating the remaining number N-1 of the total condensate flow rate W when one unit is stopped, Dividing means for dividing the current total condensate flow rate W by the remaining number (N-1), and the remaining condensate desalination which is the quotient W / (N-1) obtained by the dividing means. A condensate flow rate per apparatus is compared with a predetermined allowable value, and when the allowable value is exceeded, means for disabling the stoppage is provided.

  Furthermore, in the control device for the condensate demineralizer, the control device may be a dedicated control device attached to the condensate demineralizer.

  Furthermore, the condensate demineralizer control method according to the present invention is a condensate demineralizer control method connected to a plurality of units for purifying the condensate of a power plant, wherein When stopping one unit, a step of disabling the stop is included if the water flow rate of each condensate demineralizer after stopping exceeds a predetermined allowable value.

Furthermore, the control method of the condensate demineralizer according to the present invention is a control method of the condensate demineralizer connected to a plurality of units N in parallel to purify the condensate of the power plant. A step of calculating the current total condensate flow rate W when stopping one of the units, a step of calculating the remaining number N-1 of the total condensate flow rate W when one unit is stopped, The step of dividing the current total condensate flow rate W by the remaining number (N-1), and the remaining condensate demineralizer, which is the quotient W / (N-1) obtained by the dividing means. The step of comparing the condensate flow rate per unit with a predetermined permissible value, and if the condensate flow rate per remaining condensate demineralizer exceeds the permissible value, discontinuation is prohibited. Including the step of.

  Furthermore, the computer program according to the present invention is a computer program that causes a computer to execute each step of the condensate demineralizer control method.

  Furthermore, a recording medium according to the present invention is a recording medium on which the above computer program is recorded.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of a novel condensate demineralization apparatus can be provided.

  Furthermore, according to this invention, the control method of the novel condensate demineralization apparatus can be provided.

  Furthermore, according to the present invention, it is possible to provide a novel condensate demineralizer control apparatus that can be realized without making significant changes to the control means of existing thermal power plants.

  Furthermore, according to the present invention, it is possible to provide a novel condensate demineralizer control method that can be implemented without making significant changes to existing thermal power plant control means.

  Hereinafter, embodiments of a control device and a control method for a condensate demineralizer according to the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same element drawn on drawing, and the overlapping description is abbreviate | omitted.

  In the present invention, a new function is basically added to the control device of the condensate demineralizer used conventionally. Therefore, in order to facilitate understanding of the present invention, a control device and a control method for a condensate demineralizer that have been conventionally used will be briefly described first, and then a control of the condensate demineralizer according to the present embodiment will be described. The embodiment of the apparatus and the control method will be described while clarifying the difference from the conventional one. It should be noted that even the conventional condensate demineralizer control device and control method are technologies that are adopted in the thermal power plant owned by the applicant and are not publicly known technologies. I want to be.

[Control device and control method of conventional condensate demineralizer]
FIG. 2 is a diagram for explaining a part of the condensate system centering on the condensate demineralizer and the related devices in the subsequent stage of the condenser 5 of FIG. 1. This condensate system is in practical use at Misumi Thermal Power Plant.

  As shown in FIG. 2, the condensed water (condensate) that has passed through the condenser 5 is stored in a fixed amount in a hot well (hot water sump) 30, and the ground condenser 34 is pumped by the condensate pumps A and B 31. Sent to. Turbine ground steam is recovered by a ground condenser, heat is recovered to condensate by this heat exchanger, the condensate temperature is increased, and the condensate demineralizer 35 is sent. The condensate demineralizer 35 is a device that removes impurities in the condensate, and four towers A tower, B tower, C tower, and D tower are connected in parallel. The condensate that has passed through the condensate demineralizer 35 is increased in pressure by a condensate booster pump 37 and is sent to the boiler 15 through a deaerator (not shown).

  Although not shown in the figure, there is a condensate demineralizer SQ as a dedicated control device attached to the condensate demineralizer 35 and monitoring and controlling it.

  FIG. 3 is a diagram for explaining the condensate demineralizer control device 50 (condensate demineralizer SQ execution device) 50 for the condensate demineralizer A tower from the viewpoint of the interlock condition. That is, the conditions for permitting the stop of the condensate demineralizer A tower are specified. The other condensate demineralizers B, C, and D towers are provided with the same condensate demineralizer control devices.

  In FIG. 3, the notation ◯ indicates an OR condition, and the notation □ indicates an AND condition. As shown in the figure, the condition for stopping the condensate demineralizer A tower (A tower demineralizer stop permission condition (55)) is the control device for the condensate demineralizer for the condensate demineralizer A tower. 50 requires that the condensate demineralizer BP valve is fully open (53) or that two of the other condensate demineralizers (B to D towers) are underwater (54).

  Furthermore, the water collection system SW of the condensate demineralizer A tower is in the automatic mode (52), and the start command for the condensate demineralizer A tower has already been held (51). It is a necessary condition.

  In the condensate demineralizer control device 50 for the condensate demineralizer A tower of FIG. 3, if two of the other condensate demineralizers (B to D towers) are underwater (54), When other conditions are met, the stop permit condition (55) for the condensate demineralizer A tower is established. The present inventor has found that the control device 50 is not provided with means for monitoring and controlling the balance between the amount of condensate water (load) and the amount of water that can be passed (per condensate demineralizer). discovered. In other words, when the number of water passing through the four towers is reduced by one tower and further by one tower, there is no interlock to protect until the second tower is stopped, and it is possible to stop unconditionally by an erroneous operation.

  For this reason, there is a possibility that the condensate water amount (load) exceeds the water flowable amount (per tower of the condensate demineralizer). When such a situation occurs, the inlet pressure of the condensate booster pump at the rear stage of the condensate demineralizer decreases, and one of the condensate booster pumps may be pump tripped, resulting in a runback accident. I realized that.

[Embodiments of control device and control method for condensate demineralizer according to the present invention]
Therefore, the present inventor has developed a means for monitoring and controlling the balance between the condensate water amount and the water flowable amount. This monitoring / controlling means is preferably a means that can be realized without significant changes to the hierarchically combined control means of existing thermal power plants.

  FIG. 4 is a diagram illustrating a condensate demineralizer control device (condensate demineralizer SQ execution device) 51 for the newly developed condensate demineralizer A tower from the viewpoint of an interlocking state. That is, the conditions for permitting the stop of the condensate demineralizer A tower are specified. The other condensate demineralizers B, C, and D towers are provided with the same condensate demineralizer control devices. The control device 51 can be configured by a normal control computer.

  The condensate demineralizer control device 51 for the condensate demineralizer A tower is a condensate demineralizer control device 50 for the above-described current condensate demineralizer A tower (the portion surrounded by a broken line in the figure). In the preceding stage, a means for monitoring and controlling the balance between the condensate amount and the flowable amount is loaded.

  The control device 51 monitors the balance between the amount of condensate water and the flowable amount of water for the SQ for the condensate demineralizer, which is attached to the condensate demineralizer 35 and monitors and controls it. Therefore, it can be realized without any change to the hierarchical and multiple control means of the existing thermal power plant.

  The flow of the condensate demineralizer A tower 61 (flow rate data measured with a flow meter; the same applies hereinafter) 61, the flow rate of the condensate demineralizer B tower will be described mainly with the thick line route in the figure directly related to the present invention. 62, the flow rate 63 of the condensate demineralizer C tower and the flow rate 64 of the condensate demineralizer D tower are input to the adding means 69, and a simulated condensate flow rate (condensate water amount, that is, load) W is calculated. And then sent to the dividing means 76.

  On the other hand, a condensate demineralizer A start command (that is, water sampling confirmation of tower A. The same applies hereinafter) 65 (same as 51 in FIG. 3), condensate demineralizer B start command 66, condensate demineralizer C The start command 67 and the condensate demineralizer D start command 68 are sent to the adding means 70, the total number N of water sampling towers is calculated and sent to the subtracting means 73, where -1 is subtracted. The data of (the number of sampling towers N-1) is sent to the dividing means 76 through the SW80.

  The dividing means 76 divides the condensate flow rate / (N-1), and calculates the condensate flow rate per tower when one tower is temporarily stopped as a quotient. This “condensate flow rate per tower when one tower is stopped” is sent to the maximum / minimum determination means (H / L) 78 and compared with a reference value (allowable value). “1” is output. The reference value may be an arbitrarily determined value less than or equal to the maximum flow rate for each tower. Since the maximum flow rate is 737 tons / hour at the Misumi power station, the reference value is set to 730 tons / hour with a margin. Yes.

  Even if one column is stopped, if each column does not exceed the maximum flow rate, the output “1” is sent to the AND condition 86. Another input of the AND condition 86 is that the interlock use / non-use software switch is set to “use”, which is a condition indicating that the program is in use. The output of the AND condition 86 is sent to the condensate demineralizer controller 50 for the current condensate demineralizer A tower (portion surrounded by a broken line in the figure).

  The other elements SW72, 80, etc. are routes for ensuring safety, and are not directly related to the present invention, so the description is omitted.

  In the condensate demineralizer control device 51, when the tower A is stopped, the flow rate W / (N− of each tower in the case where the actual condensate flow rate is processed in the other B, C, D towers in advance. 1) is calculated, and it is determined whether or not the flow rate exceeds an allowable value (reference value). And when it exceeds the allowable value, the stop of the tower A is not permitted. Of course, the same control device 51 is attached to the other towers B, C, and D.

  According to the control device 51 of this condensate demineralizer, the flow rate of each tower after stopping is calculated in advance, whether or not the flow rate exceeds an allowable value (reference value), and each column is allowed If the value is exceeded, stop is not allowed. For this reason, there is no possibility that the load will exceed the allowable amount of water flow. Accordingly, there is no possibility that the inlet pressure of the condensate booster pump 31 at the rear stage of the condensate demineralizer decreases or that one of the condensate booster pumps 31 is pump-tripped to cause a runback accident.

  Further, the control device 51 can be realized without any change to the hierarchical and multiple control means of the existing thermal power plant.

[Modifications, etc.]
Although the embodiments of the present invention have been described above, it should be understood that these are examples. The present invention includes various modifications made to these embodiments.

For example, although four condensate demineralizers are connected in parallel in the embodiment, the present invention is not limited to this.

Moreover, although the control method of the condensate demineralizer was demonstrated, the computer program which performs this, and the recording medium which recorded this program are also the object of this invention.
The technical scope of the present invention is defined by the description of the appended claims.

FIG. 1 is a diagram showing an example of a thermal power plant to which the present invention is applied. FIG. 2 is a diagram for explaining a part of the condensate system centering on the condensate demineralizer and related devices in the subsequent stage of the condenser of FIG. 1. FIG. 3 is a diagram for explaining the condensate demineralizer control device (condensate demineralizer SQ execution device) for the condensate demineralizer A tower from the viewpoint of the interlock status. FIG. 4 is a diagram for explaining a condensate demineralizer control device (SQ execution device for condensate demineralizer) for the newly developed condensate demineralizer A tower from the viewpoint of the interlock status.

Explanation of symbols

5: condenser, 10: water supply, 11: steam, 15: boiler, 17: high pressure turbine, 18: medium pressure turbine, 19: low pressure turbine, 20: generator, 21: generator, 30: hot well, 31 : Condensate pump, 34: ground condenser, 35: condensate demineralizer, 37: condensate booster pump, 50: controller of condensate demineralizer, 51: controller of condensate demineralizer, 51, 65 : Condensate demineralizer A “start command” (self-maintained) 52: Condensate demineralizer A sampling system SW “automatic” 53: Condensate demineralizer BP valve “fully open” 54: Other condensate Dewatering equipment (B to D) 2 tower water passage, 55: Tower A desalination equipment stop permission condition, 61: Condensate desalination equipment A flow rate, 62: Condensate desalination equipment B flow rate, 63: Condensate desalination Device C flow rate, 64: Condensate demineralizer D flow rate, 66: Condensate demineralizer B “Start command” (self Lifting), 67: condensate demineralizer C "start command" (self-holding),
68: Condensate demineralizer D “start command” (self-holding), 70: addition means, 73: subtraction means, 76: division means, 78: H / L determination means

Claims (5)

Includes a control function for purifying the condensate of the power plant, stopping one of the condensate demineralizers connected in parallel to the plurality of units N and passing the condensate to other condensate demineralizers A control device,
Means for calculating the current total condensate flow rate W when stopping one of the plurality of vehicles N;
Means for calculating the remaining number N-1 when one is stopped;
Dividing means for dividing the current total condensate flow rate W by the remaining number (N-1);
When the condensate flow rate per remaining condensate demineralizer, which is the quotient W / (N-1) obtained by the dividing means, is compared with a predetermined allowable value and exceeds the allowable value A control device for the condensate demineralizer, comprising means for disabling the stop. The control device according to claim 1 ,
The said control apparatus is a control apparatus of the condensate demineralizer which is an exclusive control apparatus attached to the said condensate demineralizer. Including a control step of purifying the condensate of the power plant, stopping one of the condensate demineralizers connected in parallel to the plurality of units N and passing the condensate to another condensate demineralizer A control method,
A step of calculating the current total condensate flow rate W when stopping one of the plurality N,
A step of calculating the remaining number N-1 when one is stopped;
Dividing the current total condensate flow rate W by the remaining number (N-1);
A step of comparing a condensate flow rate per remaining condensate demineralizer with a predetermined allowable value, which is a quotient W / (N-1) obtained by the dividing means;
A condensate demineralizer control method including a step of disabling the stop when the condensate flow rate per remaining condensate demineralizer exceeds the allowable value. Against the computer,
The computer program which performs each step of the control method of the condensate demineralizer of Claim 3 . The recording medium which recorded the computer program of Claim 4 .

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