JP4398608B2 - Compressed air supply system for nuclear power plants - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compressed air supply system for in-house and instrumentation of a nuclear power plant.
[0002]
[Prior art]
An air system for instrumentation (hereinafter abbreviated as IA system) in a nuclear power plant is a system for supplying compressed air that is oilless and dehumidified and dedusted mainly for the operation of air operated valves and instrumentation control devices.
[0003]
In addition, the in-house air system (hereinafter abbreviated as SA system) in nuclear power plants is a system for supplying compressed air necessary mainly for desalination equipment inside and outside of each building, regeneration and backwashing of filtration equipment, and air working tools. It is.
[0004]
First, an IA system configuration will be described with reference to FIG.
As shown in the figure, this system has two air compressor series in parallel, each system comprising an air / water separator 8 to which an air compressor 6 and a rear cooler 7 are connected, and equipment connection piping. Has been. The downstream side from the steam separator 8 joins and is connected to the air storage tank 9. The downstream side of the air storage tank 9 is branched again into two systems and connected to the dehumidifying device 10. It is configured to supply to the load destination. A part of the air in the air storage tank 9 is used as compressor control air 20. And as an IA system equipment specification, one series is 100% capacity, and one series is a spare machine.
[0005]
Next, the operating state of the IA system has the highest load factor during normal plant operation and an average of about 40 to 60%, but the load factor is very low at about 10 to 20% during regular plant inspections. Since it will be in the unload operation state for a period, drain may accumulate in the equipment and may cause malfunction due to rusting.
As a countermeasure against this, an atmospheric discharge line 18 is connected between the air compressor 6 and the rear cooler 7 for the purpose of continuous exhaust.
[0006]
Next, the function of the IA dehumidifier 10 will be described.
The IA-based dehumidifying device 10 causes saturated humid air from the outlet of the air storage tank 9 to flow into the filtration unit 11 at the inlet of the hollow fiber membrane dehumidifying unit. The filtration unit 11 removes the inflow of saturated humid air to such an extent that it does not interfere with the use of the measurement control device that is a process load. The process air dedusted by the filtration unit 11 flows into the dehumidifying unit including the hollow fiber membrane element 13.
[0007]
The dehumidifying part is composed of a hollow fiber membrane element 13 and a hollow fiber membrane outlet air header 15 arranged in parallel with the hollow fiber membrane inlet air header 12 that uniformly distributes air to the hollow fiber membrane element 13. The process air that has flowed into the dehumidifying section is dehumidified by the hollow fiber membrane element 13, flows out as dry air to the hollow fiber membrane outlet air header 15, and is supplied to the plant as instrumentation air. At this time, the outlet dew point satisfies the required dew point of a specific load having the highest dew point requirement of −40 ° C. or higher (low dew point).
[0008]
On the other hand, a part of the air dried through the hollow fiber membrane dehumidifying unit is used as a bleed (atmospheric release) air required to release moisture removed by the hollow fiber membrane outside the system. Branches to section 16. The bleed air amount is required to be about 15 to 20% of the rated dehumidification flow rate.
[0009]
The bleed air control unit 16 includes a bleed air shut-off valve 14 and a bleed air pipe for supplying bleed air to the hollow fiber membrane element, and the bleed air is supplied to the hollow fiber membrane element through the bleed air pipe. It is discharged out of the system from the bleed (atmospheric discharge) line 19 together with the moisture that is supplied and removed by the hollow fiber membrane.
[0010]
Next, the system configuration of the SA system will be described with reference to FIG.
As shown in the figure, this system has two air compressor series in parallel. Each system includes an air / water separator 3 to which an air compressor 1 and a rear cooler 2 are connected, and equipment connection piping. It is configured. The downstream side from the steam separator 3 is joined and supplied to each load destination via the air storage tank 4. A part of the air in the air storage tank 4 is used as compressor control air 5. The SA-system equipment specifications are 50% capacity for 1 line and 100% capacity for 2 lines, and one line is used as a normal standby machine (single line automatic start-up as the load factor increases).
[0011]
In contrast to the IA system, the SA system is operating in a normal plant operation with a low load factor and an average of only about 5 to 10% per unit, and the maximum load factor is 100% during the regular plant inspection. Yes, the second unit rises to about 10-40%. During normal plant operation, long-term unloading operation occurs, so drainage may accumulate in the equipment, possibly causing malfunction due to rusting.
As a countermeasure, an atmospheric discharge line 17 is connected between the air compressor and the rear cooler for the purpose of continuous exhaust as in the IA system.
[0012]
In the IA-based and SA-based air compressors, operation control of pressurization (load operation) / no load (unload operation) is performed by the pressure in the storage tank. Further, the IA system and the SA system are connected to the downstream side of the air storage tanks 4 and 9 via a valve 21 by a backup pipe 22 as backups.
[0013]
[Problems to be solved by the invention]
By the way, since the operating load factor of the SA system is very low during the plant operation, it becomes an unload operation state for a long period of time, so that the drain is accumulated in the equipment, which may cause a malfunction due to rusting. is there. In contrast to the SA system, the IA system has a very low operating load factor during the plant inspection, so it will be unloaded for a long period of time, so drainage will stay in the equipment and cause rusting. It may cause malfunction.
[0014]
In addition, as the influence of rust, the control air of the conventional air compressor uses saturated humid air before drying branched from the air storage tank, and rust etc. from the inner surface of the air storage tank is mixed and the compressor itself malfunctions. There is a possibility of incurring both the IA system and the SA system.
[0015]
The dew point performance of the IA dehumidifier is designed to satisfy the dew point of -40 ° C or higher (low dew point) for the specific load with the highest dew point requirement, but this load is only a few percent of the total load. The dew point requirement is about −10 ° C., which is uneconomical as equipment specifications.
[0016]
In addition, since the IA-based hollow fiber membrane dehumidifier always consumes about 20% of the rated dehumidification flow rate constantly, the bleed air of about 20% of the rated dehumidification flow rate is out of the system even under low load in the current configuration. The amount of bleed is uneconomical.
[0017]
The present invention has been made in view of the above-mentioned circumstances, and the problem is that a nuclear power plant capable of improving the reliability of the IA and SA supply facilities and the equipment specifications and operability of the supply facilities at the same time. It is to provide a compressed air supply system.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, claim 1 includes an air compressor for an instrumentation air system and an in-house air system, and an air / water separator disposed downstream of the air compressor and connected to a rear cooler, Compressed air supply equipment comprising a hollow fiber membrane dehumidifying unit provided on the downstream side of the air / water separator and having a hollow fiber membrane element for removing moisture in the air flowing into the air / water separator in parallel with a plurality of systems The air storage tank and the equipment connection pipe are arranged at the downstream, and the air storage line and the equipment connection pipe are arranged, and the air staying in the compressor at low load is continuously exhausted and removed by the hollow fiber membrane of the hollow fiber membrane dehumidifier unit. In the compressed air supply system of a nuclear power plant provided with a continuous bleed line for releasing the moisture outside the system on the hollow fiber membrane dehumidifying unit side, the air compressor loading and unloading time of the continuous bleed line Calculated load factor of al, and controls the actual bleed amount of the bleed line based on changes in load.
[0019]
According to the first aspect, it is necessary to release the moisture removed by the function of the atmospheric discharge line provided between the compressor and the rear cooler and the hollow fiber membrane of the hollow fiber dehumidifier unit out of the system. The function of the continuous bleed line is integrated on the hollow fiber membrane dehumidifying unit side, so that the equipment configuration can be simplified.
[0021]
In addition, the dew point transition at the dehumidification unit outlet or the function of the continuous bleed line (atmospheric release) required to release the moisture removed by the hollow fiber membrane of the hollow fiber dehumidifier unit to the outside of the system or Efficient bleed amount control is achieved by controlling the bleed amount of the bleed line based on the transition of the actual load amount from the air compressor load / unload time.
[0022]
In addition, by supplying the dry air in accordance with the required dew point of the IA system load destination, the specification of the dehumidifying device is lowered and the efficient use of the dry air is achieved.
[0023]
A second aspect of the present invention provides the compressed air supply system for a nuclear power plant according to the first aspect, wherein a hollow fiber membrane dehumidifying unit is further provided on a connection line branched from the equipment connection pipe to a specific load having a high low dew point requirement. It is characterized by supplying dry air with dew point.
[0024]
According to the second aspect , the air for controlling the air compressor has conventionally used air from the compressed air system air storage tank (saturated humid air). However, since dry air is used, Reliability is improved.
[0025]
3. A compressed air supply system for a nuclear power plant according to claim 1, wherein a pipe connected to the control device of the air compressor is connected to the air storage tank, and dry air is used as control air for the compressor. It is characterized by doing.
According to the third aspect , the SA-based supply air becomes dry air having a low dew point, thereby reducing rusting in the supply pipe.
[0026]
According to a fourth aspect of the present invention, in the compressed air supply system of the nuclear power plant according to the first aspect, the in-house air system supply air is obtained by integrating the instrumentation air system air compressor system and the in-house air system air compressor system into one system. Becomes dry air with a low dew point.
According to the fourth aspect , the IA system air compressor system and the SA system air compressor system can be integrated into one system, and the equipment configuration can be simplified.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Figure 1 is a first configuration diagram of an embodiment form status of the present invention.
[0028]
As shown in the figure, the air pressurized by the air compressor 26 integrated with the IA and SA system is cooled by the rear cooler 27 to generate drain, and the drain is processed by the steam separator 28. The The IA and SA supply air that has become saturated humid air flows into the single-line hollow fiber membrane dehumidifying unit 29. The hollow fiber membrane dehumidifying unit 29 has a built-in filter, and the saturated humid air that has flowed in is removed to the extent that it does not interfere with the use of the measurement control device, which is a process load, in the filter unit.
[0029]
The process air dedusted by the filter part flows into the dehumidifying part provided with the hollow fiber membrane element 30. The dehumidifying part is configured by a hollow fiber membrane element 30 and a hollow fiber membrane outlet air header 32 arranged in parallel with a hollow fiber membrane inlet air header 31 that uniformly distributes air to the hollow fiber membrane element 30. The process air that has flowed into the dehumidifying section is dehumidified by the hollow fiber membrane element 30, flows out as dry air to the hollow fiber membrane outlet air header 32, further joins, and flows into the IA and SA air storage tank 33. On the other hand, a part of the air dried through the hollow fiber membrane dehumidifying unit 29 is branched to the bleed air control unit 39 through the bleed air flow rate adjustment valve 45 as bleed air.
[0030]
The bleed air of this dehumidifier is supplied to the hollow fiber membrane element 30 through the air pipe for bleed, and is released from the bleed line 41 together with moisture removed by the hollow fiber membrane. It also functions as a continuous exhaust between the air compressor for preventing malfunction caused by rusting of the compressor and the rear cooler. The amount of air to be bleed is detected by the dew point meter 46 provided at the outlet of the dehumidifier, and the opening degree of the bleed air flow control valve 45 is detected by the output signal 47a from the calculator 47 based on the detected dew point transition. To control the bleed flow rate to the optimum value.
[0031]
The outlet line of the IA, SA-based air storage tank 33 is divided into an SA supply line 34 and an IA supply line 35, and is further branched from the IA supply line 35 to supply a specific load requiring a low dew point. Is provided with a hollow fiber membrane dehumidifying unit 37 for generating dry air having a low dew point. A part of the air in the IA, SA system air storage tank 33 is used as compressor control air 42.
[0032]
Therefore, high dew point dry air that has been dehumidified to the extent that it does not interfere with the use of measurement and control equipment in the IA system, high dew point dry air in the SA system, and identification of mobile in-core instrumentation purge devices, etc. The load is supplied with dry air having a low dew point that satisfies the required dew point.
[0033]
In addition, since the capacity | capacitance of the conventional IA and SA system air compressor is the same, as a load factor of each supply air,
IA (40-60%) / unit + SA (5-10%) / unit = 45-70% / unit at plant operation IA (10-20%) / unit +
SA [first unit (100%), second unit (10-40%)]
= 1st unit (100%) + 2nd unit (20-60%)
At operation of two compressors, the entire IA and SA system can be covered by a single supply system.
[0034]
Further, the inner surface of the air storage tank 33 is always in an atmosphere of low dew point dry air, rusting on the inner surface of the air storage tank is suppressed, and clean dry air with a low possibility of mixing rust is supplied to the compressor control air. It will be. Furthermore, in the case of operation of each of the air compressors 26 and 26 and the hollow fiber membrane dehumidifying units 29 and 29, by appropriately opening and closing the switching valve 40a and the supply line switching valves 43 and 44 of the dehumidifying device switching line 40, Switching operation can be performed.
[0035]
Figure 2 is a block diagram of the second embodiment forms state of the present invention.
The present embodiment differs from the first embodiment of FIG. 1 in that the amount of air that is bleed is detected in the compressor body by loading time and unloading time, and the actual load factor and load amount are determined from each measurement time. The calculation unit 48 is provided, and the other components are the same. Therefore, the same components are denoted by the same reference numerals, and redundant description is omitted.
[0036]
According to the present embodiment, the opening degree of the bleed air flow rate adjustment valve 45 can be controlled based on the output signal of the load amount transition from the computing unit 48, and the bleed flow rate can be controlled to the optimum value. The formula for calculating the compressor load is as follows. That is,
Compressor load =
Load time / (load time + unload time) × compressor rated flow rate.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a compressed air supply system for a nuclear power plant that can improve the reliability of IA and SA supply facilities, and improve the facility specifications and operating economy of the supply facilities.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of the present invention.
FIG. 2 is a configuration diagram of a second embodiment of the present invention.
FIG. 3 is a configuration diagram of a compressed air supply system in a conventional nuclear power plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... SA system air compressor, 2 ... Rear cooler, 3 ... Air-water separator, 4 ... Air storage tank, 5 ... Compressor control air, 6 ... IA system air compressor, 7 ... Rear cooler, 8 ... Air Water separator, 9 ... Air storage tank, 10 ... IA dehumidifier, 11 ... Filtering unit, 12 ... Hollow fiber membrane inlet air header, 13 ... Hollow fiber membrane element, 14 ... Bleed air shutoff valve, 15 ... Hollow fiber membrane outlet Air header, 16 ... air control unit for bleed, 19 ... bleed (atmospheric discharge) line, 26 ... IA, SA air compressor, 27 ... rear cooler, 28 ... air / water separator, 29 ... hollow membrane dehumidification unit, DESCRIPTION OF SYMBOLS 30 ... Hollow fiber membrane element, 31 ... Hollow fiber membrane inlet air header, 32 ... Hollow fiber membrane outlet air header, 33 ... IA, SA type air storage tank, 34 ... SA supply line, 35 ... IA supply line, 36 ... Dedicated supply line, 37 ... hollow fiber membrane dehumidification unit 39 ... Bleed air control unit, 40 ... Dehumidifier switching line, 41 ... Bleed line, 43, 44 ... Supply line switching valve, 45 ... Bleed air flow control valve, 46 ... Dew point meter, 47 ... Calculator (dew point temperature) Signal-valve opening signal conversion), 48 ... Calculator (compressor load amount signal-valve opening signal conversion).

Claims (4)

An air compressor for an instrumentation air system and an in-house air system, an air / water separator disposed downstream of the air compressor and connected to a rear cooler, and disposed downstream of the air / water separator. Provided in parallel with a plurality of systems of compressed air supply equipment composed of a hollow fiber membrane dehumidification unit having a hollow fiber membrane element that removes moisture in the air flowing into the interior, An atmospheric discharge line for continuously exhausting the drain that stays in the compressor at the time of low load, and a continuous bleed line for releasing moisture removed by the hollow fiber membrane of the hollow fiber membrane dehumidifier unit. In the compressed air supply system of a nuclear power plant provided on the hollow fiber membrane dehumidification unit side ,
The calculated load rate from the air compressor loading and unloading time of a continuous bleed line, the actual compressed air of a nuclear power plant which is characterized in that to control the bleed amount of the bleed line based on changes in load Supply system. Nuclear power before Symbol claim 1 wherein characterized in that to provide a low dew point dry air by providing a further hollow fiber membrane dehumidifier unit to a connection line to the low dew point demanding specific loading branched from device connection pipe Compressed air supply system. Before SL connects the pipe connected to the air reservoir to the control device of the air compressor, the compressor nuclear power plant compressed air supply system according to claim 1, wherein that characterized by the use of dry air to the control air . 2. The nuclear power generation according to claim 1 , wherein the in-house air system supply air becomes dry air having a low dew point by integrating the instrumentation air system air compressor system and the in-house air system air compressor system into one system. Compressed air supply system.

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