JP3511565B2 - Compressed air dehumidifier for instrumentation - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a compressed air system dehumidifier for instrumentation of a nuclear power plant.

[0002]

2. Description of the Related Art Compressed air for instrumentation (hereinafter abbreviated as "IA") system in a nuclear power plant is oilless mainly for the operation of air operated valves and instrumentation control equipment, and dehumidification,
This system is intended to supply decompressed compressed air.

A conventional IA system configuration will be described with reference to FIG. The conventional IA system has two systems of air compressors connected in parallel, and each system has an air compressor 2 having a silencer 1 also serving as an intake filter,
It is composed of a steam separator 4 to which the rear cooler 3 is connected and a device connection pipe. The downstream side of the steam separator 4 is joined by an air storage tank 5, and compressed air is supplied to each load destination such as an air operated valve through the air storage tank 5 and the dehumidifying device 6 connected in parallel.

As shown in FIG. 3, the dehumidifying device 6 has a pre-filter 7, a dehumidifying side dehumidifying tower 8 and a regenerating side dehumidifying tower 9, which are connected to each other through pipes and serve as a suction filter. It has a blower 11 having a container 10 and an electric heater 12. Treated air flows into the dehumidification towers 8 and 9 through the dry air inlet, and the dehumidified dry air flows out through the aqua filter 13 from the outlet.

The flow of compressed air from the air intake to each load destination will be described with reference to FIG. During normal operation of the plant, compressed air is supplied in one series of operations. That is, the air sucked from the silencer 1 which also functions as an intake filter is pressurized by the air compressor 2. The temperature of the pressurized air rises simultaneously with the pressurization, and the temperature of the discharge portion of the air compressor 2 becomes considerably high.

Therefore, the rear cooler 3 cools and the condensed water generated by the cooling is separated by the steam separator 4. Downstream from the steam separator 4, the compressed air is dehumidified by a dehumidifier 6 via an air storage tank 5. The compressed air dehumidified and dedusted in the dehumidifier 6 is supplied to each load destination.

Next, the flow of compressed air in the dehumidifier 6 will be described with reference to FIG. In the dehumidifying device 6, two dehumidifying side dehumidifying towers 8 and one regenerating side dehumidifying tower 9 each filled with an adsorbent are provided. The dehumidifying side dehumidifying tower 8 dehumidifies moist air. During this period, the regeneration-side dehumidifying tower 9 finishes dehumidification and regenerates the adsorbent containing water (removing the water and drying).

Regarding the flow of air at the time of dehumidification, the air that has flowed in from the inlet of the air to be dried flows from the lower part of the dehumidification side dehumidification tower 8 through the air actuated valve and becomes dry air due to the adsorbent and from the upper part of the dehumidification tower. It flows out and is supplied to each load destination.

Next, the heating regeneration operation state will be described with reference to FIG. Regarding the flow at the time of regeneration, the air sucked from the blower 11 having the silencer 10 also serving as the suction filter is heated by the electric heater 12 and flows in from the upper part of the dehumidifying tower 9 on the regeneration side to remove the adsorbent containing water. Desorb water.

Further, conventionally, a dryer using a hollow fiber membrane is known. This dryer is composed of a hollow fiber membrane that employs a polymer material having a property that it is difficult for nitrogen and oxygen to come in and out and water vapor to easily come in and out.

When moist compressed air is supplied into the hollow fiber membrane, the partial pressure difference of water vapor between the inside and outside of the hollow fiber membrane serves as power for dehumidification, and the moist air supplied from the inlet becomes dry air and exit side. Flow out to.

By flowing a part of the outlet dry air as purge air to the outside of the hollow fiber membrane, the water vapor moving to the outside is promptly discharged into the atmosphere, and the outside of the hollow fiber membrane is always kept in a low water vapor concentration. It is maintained and continuously dehumidified.

[0013]

In the above-mentioned conventional IA-based dehumidifying device 6, a total of eight dehumidifying towers of a normal machine and a standby machine are installed, and the switching control method of these dehumidifying towers is complicated. In addition, the regeneration control method of the adsorbent using the blower 11 and the electric heater 12 in the regeneration process is complicated, and the equipment configuration is also complicated.

Further, in the adsorbent itself in the dehumidifying towers 8 and 9, a considerable amount of heat must flow into the inside of the tower in order to raise the temperature to reach the ultimate temperature for completion of heating regeneration. This is because the heated air in the dehumidifying tower does not contact the entire adsorbent uniformly, so in reality the regeneration is performed with more heat than necessary. There is a problem that balance efficiency is very poor.

Further, even in the adsorption step, the water sorption of the adsorbent is partially biased because the air flow in the dehumidifying tower is not uniform. As a result, the adsorbent is partially over-adsorbed, and the frequency of exchanging the adsorbent increases.

On the other hand, the conventional dryer using the hollow fiber membrane has the following problems. (1) There is no purge air control function. Conventional hollow fiber membrane dryers require a constant dew point performance by purging dry air, so continuous purging of dry air is required during operation. There is no control function because it is adjusted by an orifice or a manual valve.

As the IA system, two 100% capacity dehumidifiers are used.
Since one stand is installed and one stand-by is used as a stand-by, when the stand-by is used as a stand-by machine, when the stand-alone machine is isolated, the inside of the apparatus is depressurized by purging the hollow fiber membrane. For this reason, the pressure of the process drops when the device is switched at the time of failure.

When the spare machine is continuously ventilated, 2
The process flow rate will be
40% of the air is consumed and the capacity of the air compressor increases.

(2) The arrival time from the start of ventilation to the rated dew point is long. In the hollow fiber membrane, the difference in water vapor partial pressure between the inside and outside of the membrane serves as power for dehumidification, so the water vapor partial pressure of the purging air is the same as that of the inlet air in the initial stage of ventilation, so the outlet dew point is poor and gradually stabilizes over time. It takes a long time to reach the rated dew point from the start of ventilation. Therefore, it is necessary to ventilate beforehand to stabilize the dew point when switching to the standby machine.

(3) The performance is significantly reduced due to the inflow of condensed water. Since the hollow fiber membrane uses the property of gas permeability of the membrane, if condensed water flows in, gas permeation becomes difficult and the performance is significantly reduced. Therefore, it is necessary to sufficiently remove the mist at the inlet of the hollow fiber membrane.

The present invention has been made to solve the above problems, and is an IA system having a simplified equipment structure, a simplified control method, and an enhanced adsorption effect in a compressed air system dehumidifying device for instrumentation of a nuclear power plant. It is to provide a dehumidifying device.

[0022]

According to a first aspect of the present invention, a dehumidifying section in which a plurality of hollow fiber membrane elements corresponding to the amount of treated air are connected in parallel by an inlet air header and an outlet air header, and the hollow fiber membrane element is air purged. A purging air control unit, and a pressurized standby air supply unit connected to the downstream side of the inlet air header and the outlet air header,
And an air filter connected to the upstream side of the inlet air header.

[0023] The invention according to claim 2, characterized in that is provided with the device shut-off valve before KiKa圧 standby air supply unit formed by providing a device shut-off valve on the upstream side of the air filtration unit. The invention of claim 3 is characterized in that a dew point meter is provided on the downstream side of the outlet air header and on the downstream side of the pressurized standby air supply portion.

According to a fourth aspect of the present invention, the purge air control unit includes a purge air flow rate control valve, a standby minimum purge line having an orifice that bypasses the flow rate control valve, and the hollow fiber membrane element for purging. A purge air air header for supplying air.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a compressed air system dehumidifying device for instrumentation according to the present invention will be described with reference to FIG. In this embodiment, the hollow fiber membrane element 14 is connected in parallel with the hollow fiber membrane element 14 according to the amount of treated air by the hollow fiber membrane inlet and outlet air headers 15 and 16, and the hollow fiber membrane element 14 is connected. Process of the purging air control unit 18 for purging 14, the pressurized standby air supply unit 19 as a standby machine connected to the hollow fiber membrane inlet and outlet air headers 15 and 16, and the hollow fiber membrane inlet air header 15 Air filter unit 20 for removing water drops and dust etc.
And a standby device shutoff valve 21 connected to the upstream side of the air filtering section 20 and the downstream side of the hollow fiber membrane outlet air header 16 as a standby machine, the air filtering section 20, the dehumidifying section 17, and the purging air control section.
It is composed of a pipe, a valve, and a control device that connect the air supply unit 19 and the pressurization standby air supply unit 19.

In the dehumidifying device having the above structure, the process air compressed by the air compressor (not shown) first flows into the air filtering section 20 from the upstream side device shutoff valve 21 at the device inlet. The air filtration unit 20 removes rust and dust generated upstream and water droplets of condensed water generated in the pipe.

The air filtering section 20 comprises a mist separator 22 for removing water droplets, a pre-filter 23 for removing rust and dust, and a trap 24 connected to the mist separator 22. The mist captured by the mist separator 22 is discharged as a drain to the outside of the system by the trap 24 or the like. The air filtering unit 20 removes dust to the extent that it does not hinder the use of the measurement control device, which is the load of the process.

The process air dedusted by the air filtering section 20 flows into the dehumidifying section 17 having a plurality of hollow fiber membrane elements 14 connected in parallel through the hollow fiber membrane inlet air header 15 via a flow rate adjusting valve. The dehumidifying section 17 is a hollow fiber membrane element.
A hollow fiber membrane inlet air header 15 for uniformly distributing air to the hollow fiber membrane 14 and a hollow fiber membrane outlet air header 16 arranged in parallel.

The process air flowing into the dehumidifying section 17 is dehumidified by the hollow fiber membrane element 14 and flows out as dry air to the hollow fiber membrane outlet air header 16 to be supplied as IA into the plant. On the other hand, part of the air that has dried through the hollow fiber membrane element 14 is used as purge air, and the purge air control unit is used.
It is divided into 18 and stored in the purge air air header 28.

The purge air control unit 18 includes a purge air flow rate control 25 and an orifice for bypassing the flow rate control valve 25.
Standby minimum purge line 27 with throttle parts such as 26,
And a purge air air header 28 for supplying purge air to each hollow fiber membrane element 14.

Purging air is supplied from the purging air air header 28 to each hollow fiber membrane element 14 through a purging air supply pipe 29. The purge air supply pipe 29 is provided with a throttle valve 30 for adjusting the flow rate so that the purge air flow rate can be adjusted.

The device shutoff valve 21 in the standby state is the air filtering unit 20.
Installed on the upstream side of and the downstream side of the outlet air header 16,
While the dehumidifier is in standby as a standby machine, the shutoff valve 21 is closed to isolate it from the process. The two device shutoff valves 21 are automatic valves and are automatically operated by interlocking via the remote control switch 35.

Further, as a standby machine, a pressurization standby air supply section 19 for pressurizing and holding the inside of the dehumidifying device during standby is branched from the pipe of the hollow fiber membrane outlet air header 16, and a pressurization standby air cutoff valve 31 is provided. It is connected to the hollow fiber inlet air header portion 15 via. The pressurizing standby air shutoff valve 31 is for shutting off the pressurized air when a failure occurs.

Next, an operation example of the dehumidifying device according to this embodiment will be described. (1) During normal operation of the dehumidifying device, the device shutoff valves 21 installed at the inlet and the outlet of the dehumidifying device are open during the dehumidifying operation. Mist and dust are removed from the process air by the air filtering unit 20, dehumidified by the hollow fiber membrane element 14 of the dehumidifying unit 17, and supplied to the plant as dry air. The purge air flow rate control valve 25 of the purge air supply unit 18 is in the open state and supplies the purge air amount to each hollow fiber membrane element 14.

The pressurizing standby air shutoff valve 31 of the pressurizing standby air supply unit 19 is closed to shut off the inlet and outlet of the dehumidifier. Hollow fiber membrane element 14 during dehumidification
The air distribution to the hollow fiber inlet air header 15 is performed, but the adjustment of the air flow rate to each hollow fiber membrane element 14 is not necessary for the following reasons.

The hollow fiber membrane element 14 is dominant in the pressure loss of the flow path from the hollow fiber membrane inlet air header 15 to the dehumidifier outlet, and the pressure loss of the inlet and outlet air headers 15 and 16 and the distribution pipe is very small. . Therefore, a uniform flow rate flows through each hollow fiber membrane element 14.

The following monitoring instruments are installed in order to monitor the soundness of the device during dehumidification operation, and when an abnormality is detected, an alarm is issued and the device is switched to the spare device, and the device shutoff valve is installed.
21 and the pressurization standby air shutoff valve 31 are closed, and an interlock is provided to isolate the device.

1) Dew point meter 32 provided on the outlet side of the device The dew point meter 32 is provided to continuously monitor the dew point of the air properties of the dehumidifying section 17 after flowing out of the hollow fiber membrane element 14, and the hollow fiber membrane is properly dehumidified. It is confirmed that the required dew point is continuously maintained, and a signal is issued to the purge air flow rate control valve 25.

2) Differential pressure gauge 33 provided on the inlet side of the equipment 33 A differential pressure gauge 33 is installed at the inlet and outlet of the equipment to detect damage to the equipment in the equipment during dehumidification, abnormal large-scale leakage, and clogging of the filter and the hollow fiber membrane element 14. Is provided to monitor the differential pressure in the device.

(2) While the standby device is in standby as a standby device, the device shutoff valve 21 is closed at both the inlet and outlet, and the purge air flow rate control valve 25 is also closed, while the pressurization standby air supply valve 31 is closed. Open By supplying pressurized standby air, the internal pressure of the equipment is maintained during standby, and the purge air flow rate control valve is also active during standby.
Since 25 is closed, unnecessary purging can be prevented.

The air flow in the stand-by apparatus as the standby machine is also dehumidified by the process in the dehumidifying section 17 of the standby machine by supplying the dehumidified air of the process to the pressurizing standby air supply section 19. Air is supplied and the dehumidification section of the standby machine
The compressed air that has been further dehumidified by 17 is supplied to each hollow fiber membrane element 14 as a slight amount of purge air by a minimum purge line 27 that bypasses the flow rate control valve 25 of the purge air control unit 18. This enables the hollow fiber membrane element
The standby state can be maintained without reducing the dryness of 14.

In order to confirm the soundness of the device on standby, the following monitoring is performed, and when an abnormality occurs, an alarm is issued and the pressurizing standby air supply shutoff valve 30 is closed to completely isolate the device from the process. . That is, a pressure gauge 34 is provided in the hollow fiber membrane inlet air header 15 in the device to monitor the pressure inside the device, and to detect a pressure drop due to breakage of a device in the device on standby or a large amount of leakage.

As a countermeasure against the problems in the conventional hollow fiber membrane dryer, by providing a purge air control unit 18 and a pressurized standby air supply line 19, by shutting off the purge air during standby as a standby machine. Unnecessary purging can be prevented.

In the conventional hollow fiber membrane dryer, the purge air is adjusted for each hollow fiber membrane element.
In the present invention, by providing the purge air air header 27 and branching from the air header to each hollow fiber membrane element, it is possible to use only one purge air flow rate control valve 25, and the control is simplified.

2) Holding the pressure in the standby machine during standby By keeping the pressure by pressurizing during standby, the process is not depressurized even when switching to the standby machine.

(2) Countermeasures to follow the dew point at the start of ventilation The following measures are taken in the present invention for the followability of the dew point at the start of ventilation of the conventional hollow fiber membrane dryer.

1) Process for maintaining dryness of the hollow fiber membrane element in the standby state By installing the pressurization standby line 19 with dehumidified air and the minimum purge line 26, the hollow fiber membrane element in the standby state
It is possible to maintain the dry state of 14 with a slight amount of purge air, and it is possible to prevent fluctuation of the dew point when switching the device.

(3) Performance Deterioration When Condensed Water Inflows In the present invention, the mist separator 21 is used to prevent the inflow of condensed water.
Countermeasures can be taken by installing.

[0049]

According to the first aspect of the present invention, the dehumidifying part in which the pretreatment device and the hollow fiber membrane are combined, the purge air control part for purging the hollow fiber membrane, and the pressure holding function for pressurizing standby are systematized. As a result, the device control and device configuration are simplified, and it is possible to supply dry air that maintains the necessary dew point by a slight self-consumption.

According to the second aspect of the present invention, since the pressure is maintained by pressurizing the standby machine as a standby machine, it is possible to switch between the regular machine and the standby machine by the device shutoff valve without releasing the pressure. it can.

According to the third aspect of the invention, the dryness of the hollow fiber membrane is maintained by a slight amount of purging air during standby of the standby machine, so that the outlet air dew point when switching to the standby machine is stabilized early. Can be made. According to the invention of claim 4, since the dew point of the apparatus outlet air is continuously monitored and the purge air flow rate is automatically controlled, the necessary dew point can be maintained.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a compressed air system dehumidifying device for instrumentation according to the present invention.

FIG. 2 is a block diagram for explaining a conventional compressed air system for instrumentation.

FIG. 3 is a system diagram showing a compressed air system dehumidifier for instrumentation in FIG.

[Explanation of Codes] 1 ... Intake filter / silencer, 2 ... Air compressor, 3 ... Rear cooler, 4 ... Steam separator, 5 ... Air storage tank, 6 ... Dehumidifier, 7 ... Prefilter, 8 ... Dehumidifier Tower (dehumidification side), 9 ... Dehumidification tower (regeneration side), 10 ... Suction filter and silencer, 11 ... Blower, 12 ... Electric heater, 13 ... Aqua filter, 14 ... Hollow fiber membrane element, 15 ... Hollow fiber membrane inlet Air header, 16 ... Hollow fiber membrane outlet air header, 17 ... Dehumidifying section, 18 ... Purging air control section, 19 ... Pressurized standby air supply section, 20 ... Air filtering section, 21
... Device shutoff valve, 22 ... Mist separator, 23 ... Prefilter, 24 ... Trap, 25 ... Purge air flow control valve, 26 ...
Orifice, 27 ... Minimum purge line, 28 ... Purge air air header, 29 ... Purge air supply pipe, 30 ... Purge air flow control valve, 31 ... Pressurization standby air shutoff valve, 32 ... Dew point meter, 33 ... Difference Pressure gauge, 34 ... Pressure gauge, 35 ... Remote control switch.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-63-229397 (JP, A) JP-A-7-232024 (JP, A) JP-A-8-71354 (JP, A) JP-A-8- 5789 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G21D 1/00 F17D 3/14 B01D 53/26 B01D 63/02

Claims (4)

(57) [Claims] 1. A dehumidifying unit in which a plurality of hollow fiber membrane elements corresponding to the amount of treated air are connected in parallel by an inlet air header and an outlet air header, a purging air control unit for air purging the hollow fiber membrane elements, and A compressed air system dehumidifying device for instrumentation, comprising: a pressurized standby air supply unit connected to the downstream side of an inlet air header and an outlet air header; and an air filtering unit connected to an upstream side of the inlet air header. Wherein instrumentation compressed air according to claim 1, characterized by being provided with a device shut-off valve on the upstream side of the air filtration unit provided with the device shut-off valve before KiKa圧 standby air supply unit System dehumidifier. 3. The compressed air system dehumidifier for instrumentation according to claim 1, wherein a dew point meter is provided on the downstream side of the outlet air header and on the downstream side of the pressurized standby air supply section. 4. The purge air control unit, a purge air flow rate control valve, a standby minimum purge line having an orifice that bypasses the flow rate control valve, and a purge air supply unit for supplying purge air to the hollow fiber membrane element. The compressed air system dehumidifying device for instrumentation according to claim 1, comprising an air air header for use.