JP2780890B2 - Moisture meter and moisture measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture analyzer and a method for measuring moisture, and more particularly to a method for continuously and accurately measuring the amount of moisture in a flowing sample having a high moisture content such as dehydrated sludge. The present invention relates to a suitable moisture meter and a method for measuring moisture using the same.

[0002]

2. Description of the Related Art Conventionally, the Karl Fischer method is known as an electrochemical method for measuring water content, but this method is not suitable for efficiently measuring the water content of a large amount of water, such as dehydrated sludge. Because of this method, a batch-type dry weight method was used for measuring the moisture content. Recently, a method of continuously measuring the amount of water by an infrared absorption method or the like has been proposed, but it is impossible to measure the amount of water in a sample having a large amount of water of 50 to 100% by weight with high accuracy. In addition, there is a disadvantage that the sample is easily affected by the color of the sample.

[0003] The present applicant discloses in Japanese Patent Application Laid-Open No. 3-180747 that at least one pair of a cathode and a cathode capable of continuously and highly accurately measuring the amount of water in a sample having a large amount of water. A moisture meter having an electrode surface in which anodes are arranged at intervals of 1 mm or less and exposed at the tip of a resin insulating portion was proposed. However, since the surface of the resin insulating portion having the exposed electrode surface of the moisture measuring device is planar, when moisture is measured in a flowing sample using this measuring device, solid matter (dust, (E.g., hair) stagnates on the electrode surface or the electrode support portion (resin insulation portion) to generate noise. Particularly when the obtained electrolytic current value is 30 μA or less, the effect is large, and a stable moisture measurement cannot be performed. was there. In addition, when the solid matter in the sample stagnates on the electrode surface, the contact between the electrode surface and water becomes uneven, and there has been a problem that a stable measurement of the amount of water cannot be performed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to reduce the influence of solids and the like contained in a flowing sample to reduce the amount of water in the sample continuously. Another object of the present invention is to provide a moisture meter capable of measuring with high accuracy and a method of measuring moisture using the same.

[0005]

SUMMARY OF THE INVENTION The present invention provides at least one pair of a cathode and an anode connected to a power supply and a measuring unit, respectively, and a resin insulating portion fixing the cathode and the anode and exposing only a tip portion. Having an electrode width of 0.2 mm or less for the cathode and / or the anode, a gap of 0.5 mm or less for the cathode and the anode, and a shape of the resin insulating portion having a spherical shape, and A moisture meter characterized in that the electrode surface having the exposed cathode and anode has a cylindrical or spherical curved surface, and the moisture meter according to claim 1 is installed in a flowing sample, and the electrode is mounted on the electrode. The present invention relates to a method for measuring water, characterized in that, when a DC voltage of 2.5 V or more is applied to measure the water content of a specimen, the exposed electrode surface of the moisture measuring instrument is placed perpendicular to the flow direction of the specimen.

The materials constituting the cathode and anode used in the present invention include Ru (ruthenium), Rh (rhodium), Os (osmium), Ir (iridium), Pt
Platinum group elements such as (platinum), particularly Pt, are preferably used, but metals such as Tc (technetium), Ag (silver), Cd (cadmium), Re (rhenium), Hg (moisture), and Ti (titanium) A plate coated with Pt, Ru / Pt, or the like can be used.

In the present invention, the distance between the cathode and the anode is
In order to reduce the influence of the change in the conductivity of the sample, the thickness is set to 0.5 mm or less, preferably 0.1 to 0.3 mm. The electrode width of the cathode and / or the anode is 0.2 mm or less, preferably 0.05 mm, in order to prevent oxygen gas and hydrogen gas generated during electrolysis from stagnating on the electrode surface and generating noise.
０．１0.1 mm. At least one cathode and one anode
A pair may be used, but a cathode and an anode may be alternately arranged and used as a comb-shaped electrode. The length of the exposed electrode is not particularly limited. However, as the length of the electrode is longer, a larger electrolytic current value is obtained, and the influence of noise can be reduced. In the case of a comb-shaped electrode, the same effect can be obtained by increasing the number of electrodes.

FIG. 1 is an explanatory view of a moisture measuring device showing one embodiment of the present invention. FIG.
(b) is a front view thereof, and (c) is a sectional view taken along the line II of (b). In the figure, a plurality of anodes 1 and cathodes 2 are alternately arranged and connected to a power supply and a measuring unit (not shown) via lead wires 4. Except for the tip 11 of the anode 1 and the cathode 2 (the part for detecting the amount of water by contacting the sample), the anode 1 and the cathode 2 are covered with an epoxy resin or the like and fixed with the resin insulating part 3. The tip 11, that is, the electrode surface has a cylindrical curved surface (curved surface A in FIG. 1C), and the resin insulating portion 3 for fixing the electrode surface 11 has a spherical shape. By adopting such a shape, the solids in the flowing sample and the gas generated by the electrolysis can be applied to the curved surface A of the electrode surface and the spherical surface B of the resin insulating portion 3 which are arranged to face the flow direction of the sample. These are not swept away along the back of the electrode surface and remain on the electrode surface 11, so that the electrode surface can always come into contact with new moisture in the sample, and stable, high-accuracy continuous moisture measurement becomes possible.

FIG. 2 is an explanatory diagram of a method for measuring moisture in dehydrated sludge using the moisture meter of the present invention. In the figure, a dewatered sludge cake 7 containing sludge particles 8 and solid matter such as hair 9 moves in a pipe 10 at a constant speed. The moisture meter 12 of the present invention is supported by the support 6 such that the electrode surface 11 of the detection unit is opposed to the flow direction of the dewatered sludge cake 7 and installed in the flow of the dewatered sludge cake 7 in the pipe 10. Is done. With this arrangement, even if the sludge particles 8 and the hair 9 of the dewatered sludge cake 7 come into contact with the electrode surface 11 which is the detection unit of the moisture measuring device 12, the sludge particles 8 are immediately flushed to the wake of the detection unit along the flow. Therefore, the sludge can always be brought into contact with the electrode surface. In addition, since the electrode surface can always contact the dewatered sludge at a constant pressure, the amount of water in the dewatered sludge can be continuously measured with high accuracy.

The sample used in the measurement of the present invention is not limited to dehydrated sludge, and can be suitably applied to, for example, a highly water-containing slurry such as food and construction agents. Further, the moisture meter of the present invention can measure not only moisture in a flowing sample (including a sample placed and moved on a belt conveyor or the like),
It goes without saying that the present invention can also be applied to moisture measurement of a stationary sample.

[0011]

The present invention will be described below in more detail with reference to examples. Example 1 20 disk-shaped Pt plates having a thickness of 0.1 mm and a diameter of 17 mm (10
Pair), a lead wire 4 connected to a power source and a measuring unit is connected to form an anode 1 and a cathode 2 alternately.
Were arranged so that the distance between them was 0.2 mm, and a gap between the electrodes was filled with an epoxy resin to form a columnar electrode. Next, only a part of the curved surface of the columnar electrode was exposed to form a spherical resin insulating portion 3 with epoxy resin to form a moisture measuring device 12, and the moisture measuring device 12 was set on the support 6. The support 6 is mounted in a pipe 10 in which a dehydrated sludge cake 7 having a water content of 80.1% by weight moves at a constant speed so that the electrode surface 11 of the moisture measuring device faces the flow of the dehydrated sludge cake. The water content of the sludge cake 7 was measured. The relative standard deviation obtained by measuring the water content ten times was 2%. For comparison, moisture was measured in the same manner as described above using a moisture meter having a flat electrode surface described in JP-A-3-180747, and the relative standard deviation was determined. there were.

The moisture meter 12 of the present invention is provided with
The dewatered sludge cake 7 having a moisture content in the range of 85% by weight was installed in a pipe 10 through which the cake flows, and the water content of the cake was measured. At this time, the correlation coefficient of the quantitative property was 1.05.
In addition, the correlation coefficient of the quantitative property obtained in the same manner using a conventional moisture meter having a flat electrode surface was 0.80. From the above results, it was found that the moisture meter according to the present invention can measure the moisture content in the dewatered sludge cake having a high moisture content with high accuracy.

[0013]

According to the moisture meter of the present invention, since the electrode interval and the electrode width are set to a certain value or less, the influence on the change in the conductivity of the specimen can be reduced, and oxygen and hydrogen gas generated during electrolysis can be reduced. Are less likely to stagnate on the electrodes, thereby preventing the generation of noise. In addition, since the electrode surface is curved, the electrode length can be increased,
A large electrolytic current value can be obtained, and the influence of noise can be reduced. In addition, since the shape of the electrode surface and the resin insulating portion holding the electrode surface are curved, it is possible to prevent solid matter in the sample from stagnating on these surfaces, and thus to reduce the generation of noise and achieve high precision. Can measure moisture. Further, according to the method for measuring moisture of the present invention, since the electrode surface is installed perpendicular to the flow of the sample, the electrode surface can come into contact with the moisture of the sample at a constant pressure, so that stable moisture measurement can be performed. Becomes possible.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a moisture measuring device showing one embodiment of the present invention. FIG. 1 (a) is a structural explanatory diagram of the moisture measuring device, FIG. 1 (b) is a front view thereof, and FIG. A sectional view taken along the line I is shown.

FIG. 2 is an explanatory diagram of a method for measuring moisture in dewatered sludge using the moisture meter of the present invention.

[Explanation of symbols]

1 ... Anode, 2 ... Cathode, 3 ... Resin insulation, 4 ... Lead wire,
6 ... Support, 7 ... Dewatered sludge cake, 8 ... Sludge particles, 9 ...
Hair: 10: piping, 11: tip (electrode surface), 12:
Moisture measuring device, A: cylindrical curved surface, B: spherical surface.

Claims (2)

(57) [Claims] 1. A cathode and an anode connected to a power supply and a measuring unit, respectively, and a resin insulating unit fixing the cathode and the anode and exposing only a tip end thereof, / Or 0.2 mm anode electrode width
Hereinafter, the distance between the cathode and the anode is 0.5 mm or less, and the shape of the resin insulation portion is spherical, and the electrode surface having the cathode and anode exposed on the surface thereof has a cylindrical or spherical curved surface. Moisture meter characterized by having. 2. The method according to claim 1, wherein the moisture measuring device according to claim 1 is installed in a flowing sample, and a DC voltage of 2.5 V or more is applied to the electrode to measure the moisture of the sample. A method for measuring moisture, characterized in that the surface is set perpendicular to the flow direction of the sample.