JPH10277534A - Degassing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a degassing apparatus capable of measuring a corrosion speed itself continuously for a long time and safely and certainly suppressing the corrosion of piping and mechanically tough and reduced in maintenance/ inspection frequency. SOLUTION: Since a degassing apparatus is equipped with a degassing device reducing pressure by a vacuum pump 10 to degass water, a polarizing resistance type corrosion speedometer 11 detecting the corrosion speed of the degassed water and a controller 12 controlling the degassing quantity of the degassing device 9 by controlling the operation of the vacuum pump 10 on the basis of the detection signal of the corrosion speedometer 11, a corrosion speed itself is continuously measured for a long time to make it possible not only to safely and certainly suppress the corrosion of piping but also to impart mechanical toughness to reduce maintenance/inspection frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deaerator using a polarization resistance type corrosion rate meter.

[0002]

2. Description of the Related Art In recent years, boiler water, tap water, middle tap water,
Corrosion of piping such as cooling water has become a problem, and a deaerator has been installed in a water supply source to prevent the corrosion of such piping in order to degas dissolved oxygen in water that causes corrosion. FIG.
FIG. 1 is a block diagram showing a conventional deaerator disclosed in JP-A-8-10749. In the figure, reference numeral 21 denotes a water tank to which a raw water supply line 22 is connected, and reference numeral 23 denotes a replenishment provided in the raw water supply line 22. Device, 24 is a vacuum generator 25
26, a circulating pump, 27, a water supply pipe for supplying water from the water tank 21 to the membrane degassing module 24, 28, a water supply pipe for supplying deaerated water from the membrane degassing module 24 to a water use location, 29 Is the water supply pipe 28 and the water tank 2
Reference numeral 30 denotes a dissolved oxygen concentration meter for detecting the dissolved oxygen concentration in water. This dissolved oxygen concentration meter 3
Numeral 0 indicates the use of a galvanic cell type oxygen sensor utilizing an electrochemical oxidation-reduction reaction of oxygen. The oxygen permeable film is made of Teflon or polyethylene having good oxygen gas permeability. 31 is interval timer 3
The operation control device includes a circulation pump 26, a vacuum generator 25, a water level detector 33, and a dissolved oxygen concentration meter 30.
Are connected by signal lines.

Next, the operation will be described. The operation control device 31 performs the deaeration operation at the time of replenishing raw water or at predetermined intervals. If the dissolved oxygen concentration in the water detected by the dissolved oxygen concentration meter 30 is lower than a predetermined value, the deaeration operation is stopped. By continuing the pneumatic operation, useless deaeration operation is prevented while preventing corrosion of the water supply pipe 28.

[0004]

Since the conventional deaerator is constructed as described above, a thin film having extremely low mechanical strength such as Teflon or polyethylene is used as the oxygen permeable membrane of the dissolved oxygen concentration meter 30. Foreign matter in the water to be measured (for example, thread shavings at the joint of a metal pipe in plumbing work) is accelerated by the water flow and collides with the oxygen permeable membrane to break it, making accurate measurement impossible. In addition, the electrolyte inside the dissolved oxygen concentration meter 30 leaks out and contaminates water. In addition, there is a problem that maintenance and inspection must be performed frequently in order to prevent such adverse effects. Further, the life of the dissolved oxygen concentration meter 30 of the conventional deaerator is determined by the oxidative consumption of the anode electrode. Therefore, intermittent sampling measurement (sampling at a very short time interval by a digital measurement method is not included in the measurement). There was a problem in that it was necessary to extend the life, and it was not possible to perform long-term continuous measurement, which is indispensable for effectively preventing pipe corrosion.
Further, the conventional deaerator monitors the corrosion rate indirectly by measuring the oxygen concentration, which is an alternative value of the corrosion rate, with the dissolved oxygen concentration meter 30. In addition to oxygen, the type of pipe metal, its surface condition, flow velocity, water temperature, water quality, etc. have a significant effect, and monitoring and managing only the amount of dissolved oxygen is not sufficient for effective corrosion control. There were also issues.

[0005] The present invention has been made to solve the above-mentioned problems, and does not intermittently sample and measure the oxygen concentration which is an alternative value of the corrosion rate (however,
The term "intermittent sampling" refers to sampling at extremely short time intervals by a digital measurement method.
The purpose of the present invention is to obtain a deaerator that is mechanically strong and requires less maintenance and inspection, while the corrosion rate itself can be continuously measured for a long period of time to suppress pipe corrosion safely and reliably.

Another object of the present invention is to provide a deaerator capable of reliably measuring the corrosion rate according to the amount of water used.

[0007]

According to a first aspect of the present invention, there is provided a degassing apparatus for degassing water by depressurizing with a vacuum pump and detecting a corrosion rate of the degassed water. It is provided with a polarization resistance type corrosion rate meter and a control device for controlling the operation of the vacuum pump based on a detection signal of the corrosion rate meter to control the amount of deaeration of the deaerator.

According to a second aspect of the present invention, there is provided a degassing apparatus comprising a bypass means for guiding a part of the degassed water to a downstream side of the corrosion rate meter without flowing into the corrosion rate meter.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a deaerator according to Embodiment 1 of the present invention, FIG. 2 is a sectional view showing a deaerator,
3 is a sectional view showing a corrosion rate meter, FIG. 4 is an equivalent circuit diagram showing an example of the corrosion rate meter, and FIG. 5 is a graph showing an example of operation control of a vacuum pump. First, the configuration of the entire system will be described. In FIG. 1, 1 is a pump for introducing and supplying raw water to be degassed, 2 is a filter for removing foreign substances such as dust in the supplied water, 3 is a filter for detecting non-water-running operation (water cutoff, etc.) and a filter. 2, a differential pressure gauge for detecting the replacement time, etc., 4 a pressure reducing valve for setting a deaerator 9 described below to a specified pressure,
5 is a valve for opening and closing a water supply pipe to a deaerator 9 described later,
Reference numeral 6 denotes a bypass pipe that bypasses an upstream pipe and a downstream pipe of a deaerator 9 to be described later, 7 denotes a valve that opens and closes the bypass pipe 6, and 8 denotes a portion between the deaerator 9 and a corrosion rate meter 11 described below. A valve for opening and closing a pipe, 9 is a deaerator for removing dissolved oxygen from water by depressurizing with a vacuum pump 10 and deaeration, 11 is a polarization resistance type corrosion rate meter, and 12 is a corrosion rate meter 11 detection. This is a controller (control device) that controls the operation of the vacuum pump 10 based on the signal.

Next, details of the deaerator 9 will be described with reference to FIG. In FIG. 2, 9a is a main body formed in a cylindrical shape as a whole, 9b is a vacuum chamber partitioned by a partition wall 9c, and is connected to the above-described vacuum pump 10 by a vacuum pump connecting portion 9d so as to be capable of reducing pressure. . Reference numeral 9e denotes a water pipe for introducing water to be degassed into the main body 9a and leading out the degassed water. The water pipe has a central portion partitioned by a partition wall 9f and has through holes 9g and 9h. Reference numeral 9i denotes a hollow degassing tube for depressurizing the inside by inserting both open ends into the partition 9c and communicating with the vacuum chamber 9b, and is formed of an oxygen-permeable hollow degassing film. In addition,-in a figure has shown the course of water in the deaeration process.

Next, the details of the corrosion rate meter 11 will be described with reference to FIGS.
It will be described based on. This corrosion rate meter 11 utilizes a two-electrode polarization resistance method.
This uses a corrosion rate meter disclosed in JP-A-8-5598. In FIG. 3, 11a is a main body made of brass provided with an opening through which water to be measured flows, 11b is a first electrode made of iron, which is a sample electrode of a pipe through which water flows, and an inner periphery is formed by exposing an iron portion. The outer periphery is formed by applying gold plating (the material of the first electrode is the same as the material of the pipe). Reference numerals 11c and 11c denote first electrode holders made of polyacetal for accommodating and fixing the first electrode 11b.
The first electrode 11b is formed so as to be able to be taken out by dividing. Reference numeral 11d denotes a second electrode, which is a counter electrode disposed in the center of the first electrode 11b, and is formed by applying gold plating to a stainless steel round bar. 11e is a polyacetal second electrode holder for supporting and fixing the second electrode 11d.
The second electrode is cantilevered. 11f is the first electrode 11
b is a first electrode lead wire connected to a contact 11g and supplies a predetermined drive signal, and 11h is a second electrode lead wire connected to the second electrode 11d and supplies a predetermined drive signal.
Reference numeral 11i denotes a sealing portion sealed with an epoxy resin. Also,
In FIG. 4, reference numeral 11j denotes a first electrode 11b and a second electrode 1b.
A drive signal source for supplying a drive signal of a predetermined frequency to 1d, 1
Numeral 1k denotes an arithmetic unit for calculating a polarization resistance from a difference between respective measurement resistances obtained by time-divisionally supplying a low frequency drive signal and a high frequency drive signal between the first electrode 11b and the second electrode 11d.

Next, the operation will be described. As shown in FIG. 1, raw water to be degassed is introduced by a pump 1 and foreign matter such as dust is removed by a filter 2.
Flows into the deaerator 9 through a water pipe 9e shown in FIG. And
Water is supplied from the through hole 9g of the water pipe 9e to the partition walls 9c, 9 of the main body 9a.
Entering the portion surrounded by c (arrow in the figure), fills the periphery of the hollow deaeration tube 9i. At this time, since the vacuum chamber 9b of the deaerator 9 is depressurized by the vacuum pump 10, the inside of the hollow deaeration tube 9i communicating therewith is also depressurized, and the dissolved oxygen of water passes through the hollow deaeration tube 9i. It is sucked to the 9b side and degassed by this. Then, the water flows inside the main body 9a while being degassed (arrow in the figure), flows again into the water pipe 9e from the through hole 9h (arrow in the figure), and further flows into the corrosion rate meter 11.

In FIG. 3, the water flowing into the corrosion rate meter 11 comes into contact with the first electrode 11b and the second electrode 11d and flows out. At this time, the driving signal source 11j shown in FIG.
Accordingly, a low-frequency drive signal and a high-frequency drive signal are supplied in a time-sharing manner between the first electrode 11b and the second electrode 11d, and the polarization resistance is calculated by the arithmetic unit 11k from the difference between the measured resistances obtained thereby. Desired. When the polarization resistance is determined, for example, the corrosion rate can be determined by calculation using a predetermined calculation formula or the like shown in “Industrial Water Corrosion Test Method (K0100)” of JIS.

The first electrode 11b and the second electrode 11d
By constantly generating a drive signal in the meantime, it is possible to continuously monitor the corrosion rate for a long time without needing to intermittently sample the water to be measured unlike the related art. Note that the controller 12 does not necessarily need to constantly monitor in an analog manner, but may digitally sample a signal value at a constant period.

The controller 12 controls the operation of the vacuum pump 10 and controls the amount of deaeration in the deaerator 9 in accordance with the value of the corrosion rate obtained by the corrosion rate meter 11 as described above. That is, as shown in FIG. 5, when the corrosion rate reaches a predetermined value, the controller 12 is programmed in advance to operate or stop the vacuum pump 10, and the amount of deaeration in the deaerator 9 can be optimally controlled. It has become.

As described above, according to the first embodiment, since the polarization resistance type corrosion rate meter 11 is used, the oxygen concentration, which is an alternative value of the corrosion rate, is not intermittently sampled and measured. Since the corrosion rate itself is continuously measured for a long time, and the amount of deaeration in the deaerator 9 can be optimally controlled according to the value, the effect of effectively suppressing the corrosion of the piping can be obtained. Further, a corrosion rate meter 11 which is mechanically strong and has no chemicals such as an electrolyte is used without using a dissolved oxygen concentration meter having a thin film having extremely low mechanical strength and a chemical material such as an electrolyte. Since used, there is no risk of water contamination. Further, it is possible to obtain a safe deaerator which is mechanically strong, has a long service life, and has a low frequency of maintenance and inspection.

In the first embodiment, the corrosion rate meter 11 is described as using the two-electrode polarization resistance method. However, the present invention is not limited to this, and the reference electrode is parallel to the second electrode 11d. It is also possible to use a three-electrode polarization resistance method provided. In this case, further improvement in measurement accuracy can be expected. Further, the vacuum pump 10 may be constituted by an inverter type motor, and this may be proportionally controlled.
Also, the description has been made assuming that the polarization resistance is obtained by calculation from the difference between the measured resistances obtained by time-divisionally supplying a low-frequency drive signal and a high-frequency drive signal between the first electrode 11b and the second electrode 11d. , But not limited to this, for example,
It is obtained from the ratio of the average value of the response voltage immediately before and immediately after the polarity of the drive current supplied between the first electrode 11b and the second electrode 11d is inverted and the drive current, or supplied between the electrodes 11b and 11d. A section where the drive signal is open may be provided at an intermediate point where the polarity of the drive current is inverted, and the drive signal may be obtained from the ratio between the voltage value immediately after this section and the current value immediately before the open. Further, the applicant of the present application has filed Japanese Patent Application No. 8-1204.
Japanese Patent Application Laid-open No.
A corrosion rate meter and the like disclosed in JP-A-209237 and JP-A-7-318529 can also be used.

Embodiment 2 FIG. FIG. 6 is a block diagram showing a deaerator according to Embodiment 2 of the present invention. In the drawing, reference numeral 13 denotes a bypass pipe (bypass means) which bypasses the upstream pipe and the downstream pipe of the corrosion rate meter 11. ,
When the amount of water is large, a part of the water is passed through the bypass pipe 13 so as not to pass through the corrosion rate meter 11. Reference numeral 14 denotes a valve (bypass means) for opening and closing the bypass pipe 13. The other components are the same as those in the first embodiment, and thus are denoted by the same reference numerals and description thereof will be omitted.

Next, the operation will be described. Since the basic operation is the same as that of the first embodiment, different points will be described. That is, when the amount of water is large, the valve 14
(For example, an electric valve may be used as the valve 14 to open and close the valve 14 in accordance with the rotation speed of the water supply pump 1. Further, a flow system is provided, and the valve is controlled in accordance with the detected value. 14 may be opened and closed.) So that part of the water passes through the bypass pipe 13 and does not pass through the corrosion rate meter 11. This prevents an excessive load from being applied to the corrosion rate meter 11 and reliably measures the corrosion rate according to the amount of water used.

As described above, according to the second embodiment, the bypass pipe 13 and the valve 14 are provided, so that the same effects as those of the first embodiment can be obtained. Can be prevented from being applied with an excessive load, so that the effect of reliably measuring the corrosion rate according to the amount of water used can be obtained.

[0021]

As described above, according to the first aspect of the present invention, a deaerator for deaerated water by depressurizing with a vacuum pump and a polarization resistance type for detecting a corrosion rate of deaerated water are provided. And a control device for controlling the amount of deaeration of the deaerator by controlling the operation of the vacuum pump based on the detection signal of the corrosion rate meter, as in the prior art. Rather than intermittently sampling and measuring the oxygen concentration, which is a substitute value for the corrosion rate, the corrosion rate itself is continuously measured for a long time, and the amount of deaeration in the deaerator is optimally controlled according to the value. Therefore, there is an effect that the corrosion of the pipe can be effectively suppressed. Also, instead of using a dissolved oxygen concentration meter equipped with a thin film with extremely low mechanical strength, a mechanically durable corrosion rate meter without chemicals such as electrolyte was used. There is an effect that a long life and a safe deaerator can be obtained, and the frequency of maintenance and inspection is reduced.

According to the second aspect of the present invention, the apparatus is provided with the bypass means for guiding a part of the degassed water to the downstream side of the corrosion rate meter without flowing into the corrosion rate meter. In addition, it is possible to prevent an excessive load from being applied to the corrosion rate meter, so that the corrosion rate can be reliably measured in accordance with the amount of water used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a deaerator according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a deaerator.

FIG. 3 is a sectional view showing a corrosion rate meter.

FIG. 4 is an equivalent circuit diagram showing an example of a corrosion rate meter.

FIG. 5 is a graph showing an operation control example of a vacuum pump.

FIG. 6 is a block diagram showing a deaerator according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a conventional deaerator disclosed in Japanese Patent Application Laid-Open No. 8-10749.

[Explanation of symbols]

 Reference Signs List 9 deaerator 10 vacuum pump 11 corrosion rate meter 12 controller (control device) 13 bypass pipe (bypass means) 14 valve (bypass means)

Claims (2)

[Claims] 1. A deaerator for deaerated water by depressurizing with a vacuum pump, a polarization resistance type corrosion rate meter for detecting a corrosion rate of water deaerated by the deaerator, and the corrosion rate A controller for controlling the operation of the vacuum pump based on a detection signal of a meter to control the amount of deaeration of the deaerator. 2. The degassing apparatus according to claim 1, further comprising a bypass means for guiding a part of the water degassed by the degasser to a downstream side of the corrosion rate meter without flowing into the corrosion rate meter. Qi device.