JP2717057B2 - Method and apparatus for measuring specific gravity of liquid in can of crystallizer for salt production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the specific gravity of a liquid in a crystallization apparatus for salt production.

[0002]

2. Description of the Related Art In a crystallizer for salt production, the composition of the liquid in the can is an important control item affecting the purity and consolidation of the product. Based on the composition of the raw material (brine water) to be supplied to the device, the method of setting the Baume specific gravity value of the liquid in the can in each can and controlling the Baume specific gravity has been used to make the liquid composition in the can constant. Was. For the measurement of the Baume specific gravity, the liquid in the can (mother liquor or bitter liquor) is drawn out from a measuring cylinder or the like, collected, allowed to stand still to precipitate crystals, and a Baume specific gravity meter (buoy scale) is inserted into the supernatant liquid. A method of measuring the floating position has been used.

[0003]

However, in this method, the mother liquor or bitter liquor is cooled when the sample is collected or allowed to stand, so that sodium chloride or potassium chloride precipitates. Tends to occur. In addition, since the temperature of the mother liquor or bitter liquor decreases, it is necessary to correct the measured value by the temperature in order to accurately measure the Baume specific gravity. Furthermore, it is inevitable that the standing time of the sample and the reading position of the Baume hydrometer are different depending on the operator, and an error in the measured value caused by the operator occurs.
In addition, since the sampling operation and the reading of the hydrometer are performed by a measurer, that is, a person, in a salt-making process that targets a plurality of devices and has measurement items other than the Baume specific gravity, measurement is performed only once every several hours. Inevitably, it was difficult to quickly obtain a sufficient amount of information.

In addition, a high temperature (60 ° C. to 120 ° C.)
° C) as a sample, the sampling operation involved danger. The present invention is to provide a specific gravity measuring method that eliminates the above-mentioned disadvantages of the conventional liquid specific gravity measuring method using a Baume specific gravity meter, and more specifically,
Provided is a method and apparatus for measuring the specific gravity of a liquid in a crystallizer for salt production, which can obtain a highly accurate measurement value which is as small as possible and which can be obtained continuously and safely by a measurer. It is in.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, the present invention basically provides (a) a method for continuously collecting a liquid in a can of a crystallizer for salt production. (B) a bottom plate, a wall provided on the bottom plate, an outer tube fixed to the bottom plate inside the wall, An inner tube arranged substantially concentrically with the outer tube so as not to contact the bottom plate on the inside, an opening for discharging a sample provided at the bottom between the wall and the outer tube, Baume specific gravity detecting means, comprising: a sample introduction hole provided in the bottom plate at a position substantially at the center of the outer tube on the inside; and a disk provided between the lower end of the inner tube and the sample introduction hole. c) inserted into the inner tube and reflected at the tip (B) a distance detector for non-contactly measuring a moving distance of a tip of the Baume specific gravity detection floating scale with respect to a reference point. An apparatus for measuring the specific gravity of a liquid in a can of a crystallizer for salt production is disclosed.

The present invention further uses the above-mentioned specific gravity measuring device in the can of the crystallizer for salt production as a specific gravity detecting means, and the liquid in the can of the crystallizer for salt producing is supplied to the specific gravity detecting device via a sampling line. Measuring the specific gravity of the liquid in the can by contactlessly measuring the moving distance of the specific gravity detecting means with respect to the reference point in accordance with a change in the specific gravity of the supplied liquid in the can. Also disclosed is a method for measuring the specific gravity of a liquid in a can of a crystallizer for salt production characterized by the following.

In the present invention, it is particularly preferable to use an ultrasonic distance detector as the non-contact type distance detector, and to attach a Teflon disk for ultrasonic reflection to the tip of the Baume specific gravity detection float. This is a preferred mode, and it is possible to obtain a more accurate measurement value that is not influenced by the measurer. As a reflection plate, it is resistant to corrosion and has a high temperature (60 to 12
0 ° C.), and may be a Teflon plate, a titanium plate, a stainless steel plate (duplex stainless steel plate), a glass plate, or the like. A strong material is preferred. Further, the Baume specific gravity detecting means may be further provided with a washing water supply line, whereby the precipitated crystals can be easily dissolved and removed, and the occurrence of measurement errors can be further avoided.

[0008]

In the method and apparatus for measuring the specific gravity of the liquid in a crystallizer for salt production according to the present invention, the liquid in the can of the crystallizer is continuously supplied to a Baume specific gravity detecting means via a sampling line. . The supplied sample overflows while being kept at a constant liquid level in the measurement cell, and is sequentially discharged out of the system. In accordance with the change in the specific gravity of the sample in the measurement cell, the floating scale for detecting a Baume specific gravity floats and sinks, and the distance of the tip to the reference position changes. The change in the distance is constantly measured by a non-contact type distance detector such as an ultrasonic range finder.

[0009] The sampling of the sample can be continuously performed by opening and closing an appropriate valve device through a sample collecting line, and there is no danger and precipitation of sodium chloride and potassium chloride due to cooling of the sample can be avoided as much as possible. In particular, by making the measurement cell a multilayer tube structure, it is possible to eliminate the influence of the temperature drop of the sample, and to obtain a value without measurement error without performing any operation such as temperature compensation.

[0010]

The method and apparatus for measuring the specific gravity of liquid in a can of a crystallization apparatus for salt production according to the present invention will be described in more detail with reference to the following examples. FIG. 1 shows a conventionally known injection-mixing type crystallizer as an example of a crystallizer. Basically, a mother liquor is extracted from a crystallizer 1 of a crystallizer by a pump 2 and a heat exchanger. After receiving the heat exchange in step 3, the crystallization can 1 is again supplied from below the crystallization can 1 into the can by a jet flow to mix the crystal suspension. A seed crystal pot 4 supplies sodium chloride crystals into the can when necessary. Also,
Reference numeral 5 denotes a pot for collecting a crystallization slurry from the crystallizer by a batch method. The mother liquor circulation line A from the crystallization can 1 to the heat exchanger 3 is branched from a sample collection line B having a pump P in the middle thereof. A measuring cell 10 of the means is arranged.

FIG. 2 is a sectional view showing an embodiment of the measuring cell 10 of the Baume specific gravity detecting means used in the method for measuring the specific gravity of a liquid in a can according to the present invention.
And an outer tube 20 and an inner tube 30 which are arranged concentrically with respect to the central axis of the bottom plate 12. At the center of the bottom plate 12, a sample introduction hole 13 is formed, to which the tip of a sample collection line B, which is a branch pipe from the mother liquor circulation line A, is connected. An opening 14 for discharging the sample is formed.

The outer tube 20 has a smaller diameter but a higher height than the outer tube 11, and is fixed to the bottom plate 12. As shown in detail in FIG. 3, the inner pipe 30 is attached to the inner side of the outer pipe 11 in a suspended state by a locking piece 31, and an opening 32 is provided in the peripheral wall. Further, a circular flange 33 extending outward is fixed to the bottom of the inner tube 30, and a disk 34 having substantially the same diameter is integrally held by a fitting 35 below the circular flange 33. I have. The inner diameter of the inner tube 30 is set to be somewhat larger than the air chamber portion of the Baume specific gravity detecting buoy 40 described later.

A float 40 for detecting Baume specific gravity is inserted into the inner tube 30. The float scale 40 is preferably made of Teflon or polycarbonate resin, and it is desirable to reduce the diameter and height of the air chamber 41 for the purpose of increasing the measurement accuracy and widening the measurement range. Floating balance 4
A disk 43 preferably made of Teflon resin is attached to the upper end of the zero round bar 42.

A mother liquor, which is a sample, is withdrawn from a mother liquor circulation line A by a pump P, and is introduced into a space in an outer tube 20 through a sample introduction hole 13 formed in a bottom plate 12 of a measurement cell 10 through a sample collection line B. . Pump P and sample introduction hole 1
An opening / closing valve may be provided in the sample collection line B between Step 3 and Step 3 to interrupt the sample introduction. The flowing sample circulates along the disk 34 while abutting against the disk 34 located at the bottom of the inner tube 30 and reducing the flow velocity, ascends between the outer tube 20 and the inner tube 30 and simultaneously forms the circular flange 33 with the circular flange 33. It also enters the inside of the inner tube 30 through the gap with the plate 34. Further, the sample liquid between the outer pipe 11 and the inner pipe 30 and the sample liquid in the inner pipe 30 can move through many openings 32 formed in the side wall of the inner pipe 30.

With the above-described configuration, the sample continuously flows into the sample cell 1 by keeping the valve of the sample collection line B open. As shown in FIG. 2, the inflowing sample finally overflows from the upper portion of the outer tube 20, flows down along the outer wall surface thereof, and is then discharged out of the system through a sample discharging opening 14 formed in the bottom plate 12. Due to the overflow, the liquid level of the sample in the inner tube 30 becomes constant at the overflow height, and the floating scale 40 for detecting the specific gravity of the Baume occupies the floating position according to the specific gravity of the sample. At this time, by providing the disk 34 below the inner tube 30, the fluctuation of the liquid surface caused by the inflow of the sample is prevented, and as a result, the unnecessary movement of the Baume specific gravity detection float 40 is prevented as much as possible.

As shown in FIG. 2, in the apparatus according to the present invention, a non-contact type distance detector, preferably an ultrasonic distance detector 50 is arranged at a predetermined position on the axis of the float scale 40 for detecting Baume specific gravity. . The ultrasonic waves emitted by the ultrasonic distance detecting device 50 are reflected on a disk 43 made of Teflon resin formed at the tip of the float 40 for detecting the Baume specific gravity, and the reflected waves are measured. Reference numeral 51 denotes a display unit. Thereby,
The position of the Baume specific gravity detection float 40 with respect to the reference position is measured. If necessary, the valve of the sample supply line B may be closed for the purpose of stabilizing the position of the float 40 during reading.

The method and apparatus for measuring the specific gravity of the liquid in the can of the crystallization apparatus for salt production according to the present invention have the above-described configuration, and provide the following advantages. The sample cell 1 has a multilayer tube structure, and a sample is continuously supplied thereto. Then, the floating scale 40 for detecting Baume specific gravity is used.
The sample (mother liquor or bitter) is inserted into the inner tube 30 and is kept warm by the sample flowing in the outer tube 20.
There is no error in the measured value of the Baume specific gravity due to precipitation of sodium chloride or potassium chloride due to cooling of the powder.

Further, since the inner tube 30 into which the float scale 40 is inserted as described above is kept warm by the sample itself, the measurement can be performed without lowering the temperature of the measurement sample, and an operation such as temperature compensation is not required. . Since the sample is continuously supplied to the sample cell, the influence of the standing time and the like as in the conventional method can be eliminated.
In addition, by using a non-contact type (ultrasonic type in the above-described embodiment) distance detector, it is possible to avoid a movement error of equipment due to crystal precipitation inevitably occurring in the salt production process. Further, continuous measurement is possible, and a change in the liquid composition in the can can be strictly detected.

Since the sample can be collected and measured only by an appropriate valve operation, the danger associated with taking out the sample can be avoided. In addition, by automating the valve operation by appropriate sequence control,
Avoidance of danger and automation of measurement can be easily achieved. By using, for example, a Teflon disk as the ultrasonic reflecting portion at the tip of the float scale 40, the surface state and weight change due to corrosion may occur even though the sample is in an environment where the temperature is high and corrosion is likely to occur. Measurement errors are prevented. Further, in the measurement environment, the disk must be disposed in a place where vapor or water droplets generated from the sample tend to adhere, but the inconvenience can be considerably avoided by the water repellency of Teflon.

FIG. 4 shows another embodiment of the Baume specific gravity detecting means according to the present invention. In this example, two valves V1 and V2 are arranged in the sample supply line B,
Further, a washing water introduction line D and a washing liquid discharge line E are connected to a pipeline between the valves V1 and V2, and a valve V3 and a valve V4 are provided, respectively. A cleaning liquid supply source such as tap water is connected to the cleaning liquid introduction line D. Further, the inner pipe 30 extends upwardly from the extension 30a.
The ultrasonic distance detector 50 is disposed at the closed upper end of the extension 30a.

In this example, when the specific gravity of the sample liquid is measured, the measurement is performed with the valves V3 and V4 closed and the valves V1 and V2 opened, but when the measurement is not performed, the valve V3 is not measured.
1. By closing the valve V4 and opening the valve V3 provided on the washing water introduction line D, washing water such as tap water can be supplied into the measuring cell 10. This makes it possible to dissolve and remove the crystals precipitated in the overflow area or the like due to the cooling of the sample, and it is possible to continuously obtain highly accurate measured values. After the cleaning operation is completed, the valve V
By closing the valve 3 and opening the valve V4, the washing water and the crystals are discharged out of the apparatus through the washing liquid discharge line E.

In the above-described embodiment, an ultrasonic wave-based distance detector is used as a means for non-contactly measuring the moving distance of the tip of the floating scale for detecting the Baume specific gravity with respect to the reference point. However, it will be easily understood that the distance measuring means by light may be used. Further, the jet mixed type crystallizer shown in FIG. 1 is merely an example as a crystallizer, and is effectively used for other crystallizers such as a perfect mixed type crystallizer 100 as shown in FIG. It will also be understood that. In that case, the sampling line B for continuously collecting the liquid in the can is branched from the circulation line 110.

[0023]

As described above, the method and apparatus for measuring the specific gravity of the liquid in the can of the crystallizer for salt production according to the present invention have the above-mentioned structure, and therefore the specific gravity of the liquid in the tube can be continuously measured without measurement error. can do.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a method for measuring a specific gravity of a liquid in a can according to the present invention is applied to a jet mixing type crystallization apparatus.

FIG. 2 is a diagram showing details of a liquid specific gravity measuring device in a can.

FIG. 3 is an enlarged partial cross-sectional view of a sample cell.

FIG. 4 is a view showing another embodiment of a liquid specific gravity measuring device in a can.

FIG. 5 is a view showing a state in which the method for measuring the specific gravity of a liquid in a can according to the present invention is applied to a complete mixing type crystallization apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Crystallization can of injection mixing type crystallizer, 3 ... Heat exchanger, 4 ...
Seed crystal pot, 5: Pot for collecting crystallization slurry, 10: Cell for measuring the specific gravity of liquid in the can, 40: Floating balance, 50: Ultrasonic distance detector, B: Sample collection line

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Shimizu 4-13-20 Sakami, Odawara-shi, Kanagawa Japan Tobacco Inc. Seawater Research Institute (56) References JP-A-4-48255 (JP, A) JP-A-52-68453 (JP, A) JP-A-4-95821 (JP, A) JP-A-1-66056 (JP, U) JP-A-61-50266 (JP, U) JP-B-59-53088 (JP, B2) “Chemical Dictionary 8” (Showa 54-11-10), Kyoritsu Shuppan Co., Ltd. 771

Claims (5)

(57) [Claims] 1. A sample collection line for continuously collecting the liquid in a can of a crystallizer for salt production, (b) a bottom plate disposed at a tip of the sample collection line, and a bottom plate provided on the bottom plate. A wall portion, an outer tube fixed to the bottom plate inside the wall portion, an inner tube arranged substantially concentrically with the outer tube so as not to contact the bottom plate inside the outer tube, An opening for sample discharge provided at the bottom between the wall and the outer tube; a sample introduction hole provided in the bottom plate at a position substantially at the center of the outer tube inside the outer tube; A disk provided between the lower end and the sample introduction hole; and a Baume specific gravity detecting means, (c) for detecting a Baume specific gravity inserted in the inner tube and having a reflector mounted at the tip. (D) Floating balance for detecting Baume specific gravity Distance detector for contactless measuring the distance traveled to the reference point of the end, the can in the specific gravity measuring apparatus salt manufacturing a crystallizer, characterized in that it comprises a city. 2. The salt detector according to claim 1, wherein the distance detector is an ultrasonic distance detector, and the reflection plate provided at the tip of the floating scale for detecting Baume specific gravity is a Teflon disk. A device for measuring the specific gravity of liquid in a crystallizer. 3. The apparatus according to claim 2, wherein said Baume specific gravity detecting means is further provided with a washing water supply line. 4. A method for measuring the specific gravity of a liquid in a can of a crystallizer for salt production according to any one of claims 1 to 3 as a specific gravity detecting means, and the liquid in the can of the crystallizer for salt production is sampled through a sampling line. The specific gravity of the liquid in the can is measured by continuously supplying the specific gravity to the specific gravity detecting means, and non-contactly measuring a moving distance of the tip of the float scale with respect to a reference point according to a change in the specific gravity of the supplied liquid in the can. A method for measuring the specific gravity of a liquid in a can of a crystallizer for salt production, characterized by measuring the following. 5. The method according to claim 4, wherein the non-contact measurement is performed by ultrasonic waves.