JP3347020B2 - Water treatment method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a water treatment method for treating water to be treated containing a silicon compound and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, various types of geothermal power generation have been known in which underground steam or hot water is taken out through a well and a steam turbine is turned to generate power. It contains many inorganic substances such as silicates, aluminosilicates, and calcium carbonate, and grows as scales on the inner peripheral surface of pipes, and the inner diameter of pipes becomes smaller, which hinders removal of steam and hot water. Become like For this reason,
For example, a configuration is known in which a pipe having a double pipe structure in which a flexible tube is coaxially provided in a steel pipe is used to peel scale attached to an inner peripheral surface by expanding and contracting the tube.

[0003]

However, a special pipe having a double-pipe structure is very expensive and the piping work is complicated, so that the workability cannot be improved and the facility cost cannot be reduced.
Further, even if this special piping is used, in the case of the direct system in which the steam turbine is directly turned by the steam, it is not possible to prevent the adhesion and growth of the inorganic substance to the steam turbine. Therefore, there is a problem that power generation cannot be performed efficiently at low cost.

[0004] The present invention has been made in view of the above problems, and an object of the present invention is to provide a water treatment method and an apparatus therefor, in which generation of scale is suppressed and water to be treated is efficiently treated.

[0005]

According to a first aspect of the present invention, there is provided a water treatment method comprising: flowing water to be treated containing a silicon compound into a vessel containing a treatment material containing a fluorine compound; Ultrasonic waves are applied to the material.

[0006] Then, ultrasonic waves are applied to the treatment material containing the fluorine compound contained in the container to elute hydrogen fluoride generated by the decomposition of a very small amount of the fluorine compound into the water to be treated stored in the container, It reacts with the silicon compound in the water to be treated to be solubilized and suppresses generation of scale.

According to a second aspect of the present invention, in the water treatment method according to the first aspect, the fluorine compound is calcium fluoride.

[0008] Then, since the fluorine compound uses a treatment material of calcium fluoride, by applying ultrasonic waves, hydrogen fluoride and calcium hydroxide are generated, calcium hydroxide is dissolved in the water to be treated, and hydrogen fluoride is dissolved. It reacts with the silicon compound to solubilize it, thereby suppressing the generation of scale.

[0009] The water treatment method according to claim 3 is the water treatment method according to claim 1 or 2, wherein the treatment material is fluorite.

Since fluorite which contains calcium fluoride at a high level and is easy to handle is used as a treatment material, the generation of scale is efficiently and easily suppressed.

According to a fourth aspect of the present invention, in the water treatment method according to any one of the first to third aspects, the water to be treated is groundwater for geothermal power generation.

As the water to be treated, groundwater for geothermal power generation containing a high concentration of aluminosilicate, which is a silicon compound whose temperature is lowered by pumping and solidified by contact with air to easily produce scale, is considered. Therefore, generation of scale at the time of power generation is prevented and power is efficiently generated.

According to a fifth aspect of the present invention, in the water treatment method according to any one of the first to fourth aspects, the content of the silicon compound in the water to be treated is detected, and the content of the detected silicon compound is determined. Correspondingly, at least one of the wavelength of the ultrasonic wave and the irradiation time is fixedly set.

Further, since at least one of the wavelength of the ultrasonic wave applied to the treatment material containing the fluorine compound and the time of applying the ultrasonic wave is fixedly set in accordance with the detected content of the silicon compound, the scale is efficiently set. The occurrence is prevented.

According to a sixth aspect of the present invention, there is provided a water treatment apparatus comprising: a container for storing water to be treated containing a silicon compound so as to be able to flow in and out; And an ultrasonic wave generating means for applying an ultrasonic wave to the processing material.

Then, ultrasonic waves are applied to the treatment material containing the fluorine compound contained in the container into which the water containing the silicon compound has flowed by the ultrasonic wave generating means, so that the fluorine contained in the treatment water stored in the container. Hydrogen fluoride generated by the decomposition of a very small amount of the compound is eluted, reacted with the silicon compound in the water to be treated, solubilized, and the generation of scale is suppressed.

According to a seventh aspect of the present invention, in the water treatment apparatus according to the sixth aspect, the fluorine compound is calcium fluoride.

[0018] Since the fluorine compound uses a treatment material of calcium fluoride, the application of ultrasonic waves produces hydrogen fluoride and calcium hydroxide. The calcium hydroxide is dissolved in the water to be treated, and the hydrogen fluoride is dissolved. It reacts with the silicon compound to solubilize it, thereby suppressing the generation of scale.

The water treatment apparatus according to claim 8 is the water treatment apparatus according to claim 6 or 7, wherein the treatment material is fluorite.

Since fluorite, which contains calcium fluoride at a high level and is easy to handle, is used as the treatment material, the generation of scale is efficiently and easily suppressed.

According to a ninth aspect of the present invention, in the water treatment apparatus according to any one of the sixth to eighth aspects, the water to be treated is groundwater for geothermal power generation.

The water to be treated is groundwater for geothermal power generation, which contains a high concentration of aluminosilicate, a silicon compound whose temperature is lowered by pumping and which is solidified by contact with air to easily produce scales. Therefore, generation of scale at the time of power generation is prevented and power is efficiently generated.

According to a tenth aspect of the present invention, there is provided the water treatment apparatus of the sixth aspect.
In the water treatment apparatus according to any one of Items 9 to 9, the ultrasonic wave generating means includes a control means for fixedly setting at least one of the wavelength of the ultrasonic wave and the irradiation time in accordance with the content of the silicon compound in the water to be treated. It is provided.

Further, since at least one of the wavelength of the ultrasonic wave applied to the treatment material containing the fluorine compound and the time of applying the ultrasonic wave is fixedly set in accordance with the detected content of the silicon compound, the scale can be efficiently scaled. The occurrence is prevented.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the water treatment apparatus of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a geothermal power generation facility. This geothermal power generation facility 1 has a discharge valve 4 in a well formed by burying a buried pipe 3 substantially vertically at a predetermined depth in the ground 2. The extraction pipe 5 is connected. A pipe 7 having a valve 6 is branched and connected to the extraction pipe 5, and a back pressure turbine 9 provided with a generator 8 is connected to the pipe 7.
The back pressure turbine 9 is connected to a branch pipe 11 for collecting a part of the processing target, which is groundwater such as discharged steam or hot water, for use as a heat source such as heating.
A discharge pipe 12 is connected, which conveys the discharged water to be buried 3 to the ground 2 again.

Also, the upstream side of the discharge pipe 5 and the discharge pipe
The water treatment apparatus main body 21 is connected to the downstream side of the pipe 12.
As shown in FIG. 1, the water treatment apparatus main body 21 has a bottomed substantially cylindrical container 23 whose upper surface is closed by a lid 22 so as to be openable and closable. The container 23 has an opening (not shown) through which the water to be treated flows in and an outlet (not shown) through which the water to be treated stored in the container 23 flows out. Further, the vessel 23 is connected to an inflow pipe 24 that communicates with the inflow hole and connects the extraction pipe 5 and the discharge pipe 12.
Further, the vessel 23 is connected to an outflow pipe 25 which communicates with the outflow hole and is connected to the extraction pipe 5 and the discharge pipe 12.

At the bottom of the container 23, an ultrasonic generator 27 as ultrasonic generating means is provided. Also,
In the container 23, a fluorite 28, which is a processing material containing calcium fluoride, is placed and stored on the upper surface of the ultrasonic generator 27 which emits ultrasonic waves. In the fluorite 28, for example, the capacity of the container 23 is about 1 liter and the hardness of the water to be treated is 22 degrees.
That is, when the total amount of the aluminosilicate is, for example, 0.5 wt% and other impurities such as silicon dioxide are contained at 0.5 wt%, and the amount to be treated is 50 t / h, the particle size is about 3 to 5 mm and about 20 wt.
0 g is stored.

The ultrasonic generator 27 is connected to a control means (not shown) for controlling the wavelength and time of the ultrasonic wave to be emitted based on the input data.

Next, the operation of the above embodiment will be described.

First, the hardness, temperature and flow rate of the water to be treated spouted from the well are measured. As the measurement of the hardness, temperature and flow rate, in addition to the measurement by the sensor, a silicon compound as an impurity such as aluminosilicate or silicon dioxide which is an inorganic substance in the water to be treated may be directly quantified.

Then, the water to be treated spouted from the well is
The gas is caused to flow into the container 23 from the inflow hole via the extraction pipe 5 and the inflow pipe 24. Then, an ultrasonic wave is generated from the ultrasonic generator 27 at a predetermined wavelength for a predetermined time, that is, in accordance with the amount ratio of the inorganic substance contained in the water to be treated, and is applied to the fluorite 28 stored in the container 23. By applying ultrasonic waves to the fluorite 28, as shown by the reaction formula of CaF ₂ + 2H ₂ O → Ca (OH) ₂ + 2HF, calcium fluoride (CaF ₂ ) in the fluorite 28 Part of the calcium fluoride (CaF ₂ ) eluted into the water is decomposed into calcium ions (Ca ²⁺ ) and fluorine ions (F ⁻ ), and calcium ions (Ca ²⁺ ) and fluorine ions (F ^- ) And calcium hydroxide (Ca (O
H) ₂ ) and hydrogen fluoride (HF) are produced. In addition,
This hydrogen fluoride (HF) is a strong acid and is dissolved in water to form hydrofluoric acid.

The amount of hydrogen fluoride produced is such that, for example, when ultrasonic waves are applied to the fluorite 28 under the above conditions, 115 mg / liter is dissolved in the water to be treated. Further, the wavelength of the ultrasonic wave and the time for applying the ultrasonic wave are set so that the generated hydrogen fluoride (HF) becomes 1 or less in molar ratio with respect to the silicon compound contained in the water to be treated.

Next, the decomposed hydrogen fluoride (HF) is
It reacts with the inorganic substances in the water to be treated, that is, for example, feldspar (K) as a crust component as an aluminosilicate which is a silicon compound.
AlSi ₃ O ₈ ), 4KAlSi ₃ O ₈ + 64HF → 4KF + 4AlF ₃ +
As shown by the reaction formula of 12SiF ₄ + 32H ₂ O, water-soluble potassium fluoride (K
F) produces water-soluble aluminum trifluoride (AlF ₃ ), volatile silicon tetrafluoride (SiF ₄ ) and water (H ₂ O).

By the way, since silicon tetrafluoride (SiF ₄ ) has high reactivity with water, 3SiF ₄ + 4H ₂ O → 2H ₂ SiF ₆ + Si (OH)
_As shown by the reaction formula 4, silicon tetrafluoride (SiF ₄ ) reacts violently with water to form water-soluble hexafluorosilicic acid (H ₂ S).
iF ₆ ) and colloidal silicic acid (Si (OH) ₄ ). Hexafluorosilicic acid (H ₂ SiF ₆ ) is a strong dibasic acid, for example, as shown by a reaction formula of 2KOH + H ₂ SiF ₆ → K ₂ SiF ₆ + 2H ₂ O 2NaOH + H ₂ SiF ₆ → Na ₂ SiF ₆ + 2H ₂ O And water-soluble fluorosilicates such as potassium hexafluorosilicate (K ₂ SiF ₆ ) and sodium hexafluorosilicate (Na ₂ SiF ₆ ) by combining with various impurities in the water to be treated.

It should be noted that toxic potassium fluoride (KF)
Has a very small amount of about 20.87 mg / liter. The water to be treated, such as groundwater, is weakly alkaline in a state in which various mineral substances are dissolved, and is further generated with strong acids such as hydrogen fluoride (HF) and hexafluorosilicic acid (H ₂ S).
Since iF ₆ ) is also very small, potassium fluoride (KF) combines with sodium ions (Na ⁺ ) contained in the water to be treated and is non-toxic, water-soluble potassium hexafluorosilicate (K ₂ SiF ₆ ) Sodium fluorosilicate (N
a ₂ SiF ₆ ) and the like are generated and participate in the decomposition of the silicon compound, so that they do not remain, and there is no toxicity of the water to be treated after the treatment.

Therefore, feldspar (KAlSi ₃ O ₈ ) and feldspar (NaAl) which crystallize due to changes in temperature, pH, etc.
Si ₃ O _8), anorthite _{(CaAl 2 Si 2 O 8)} , square fluoride stone _{(NaAlSi 2 O 6 · H 2} O), Mitsubishi fluoride stone ((C
_{a, Na 2) Al 2 Si} 4 O 12 · 6H 2 O), muscovite _{(KAl 2 (Si 3 Al)} O 10 (OH) 2) aluminosilicates and silicon dioxide is a crustal component such as (SiO ₂₎ Silicon compounds such as potassium hexafluorosilicate (K ₂
SiF ₆ ) and sodium hexafluorosilicate (Na ₂ S)
iF ₆ ), calcium hexafluorosilicate (CaSiF)
₆ ) A scale formed by decomposing and forming into water-soluble compounds such as colloidal silicic acid (Si (OH) ₄ ) and depositing crustal components in the passage of the water to be treated in the geothermal power plant 1 Can be prevented. Even if a scale is generated, the scale is, for example, a calcium-based compound or a magnesium-based compound that can be easily peeled off, and the calcium-based compound or the magnesium-based compound contained in the water to be treated of the geothermal power generation facility 1 and the aluminum silicate By bonding with a salt, a strong compound such as cement, for example, a compound such as zeolite can be prevented from being strongly crystallized.

As described above, according to the above embodiment, since the ultrasonic wave is applied to the fluorite 28 stored in the container 23 into which the water to be treated flows, calcium fluoride (a main component of the fluorite 28) is used. A part of CaF ₂ ) is decomposed in small amounts and hydrogen fluoride (HF) and water-soluble calcium hydroxide (Ca (O
H) ₂ ) is generated, and silicon compounds in the treated water, which is a groundwater for geothermal power generation that is particularly large and greatly affected by the generation of scale, is decomposed and formed into a water-soluble compound by hydrogen fluoride (HF). As a result, the generation of strong scale can be suppressed, and it will adhere to the pipes and blockage, which will hinder the pumping of groundwater, and the generated scale will peel off and blockage or damage each part in the pipes. Even if the well is re-excavated frequently or adheres to the back-pressure turbine 9, which greatly reduces the amount of power generation even if a very small amount adheres, the amount of power generation can be prevented from decreasing, and the efficiency of geothermal power generation can be improved.

Further, in the above embodiment, by providing the water treatment apparatus main body 21 in the water channel to which the scale has once adhered, the adhered scale can be dissolved and removed, thereby suppressing the generation of scale. It also has scale removal performance.

Then, an ultrasonic wave is applied to hydrogen fluoride (H
As a treatment material for producing F), calcium fluoride (Ca)
Since fluorite 28 mainly composed of F ₂ ) is used, a small amount of hydrogen fluoride (HF) can be generated, and hydrogen fluoride (HF) remains to damage each part of the geothermal power generation facility 1 or generate power. Even if the water to be treated used in the process is returned to the ground again, no harm is caused, handling is easy, and a predetermined amount of hydrogen fluoride (HF) that suppresses the generation of scale can be easily generated, and water treatment can be easily performed. it can.

In the above-described embodiment, water to be treated such as steam or hot water for geothermal power generation is treated in the water treatment apparatus main body 21. However, for example, silicon compounds and calcium such as wastewater in waste treatment are used. It can be used for the treatment of any water to be treated which contains a compound or the like and produces scale.

The container 23 is provided with a flow straightening plate or the like in the container so that the inflowing water to be treated stays for a predetermined time.
Any structure can be used.

In the above description, the main body of the water treatment apparatus 21 is connected to the upstream side of the discharge pipe 5 and the downstream side of the discharge pipe 12, respectively. Only one may be provided on the upstream side of the route.

[0044]

According to the water treatment method of the first aspect, ultrasonic waves are applied to the treatment material containing the fluorine compound contained in the container, and a very small amount of the fluorine compound is contained in the water to be treated stored in the container. Hydrogen fluoride generated by decomposition is eluted and reacted with the silicon compound in the water to be treated and solubilized, so that the generation of scale on the downstream side can be suppressed, and the operation and treatment of the water to be treated on the downstream side can be reduced. Efficient and easy.

According to the water treatment method of the second aspect, in addition to the effects of the water treatment method of the first aspect, since the fluorine compound uses a treatment material of calcium fluoride, the fluorine compound is applied by applying ultrasonic waves. Hydrogen and calcium hydroxide are generated, calcium hydroxide is dissolved in the water to be treated, and hydrogen fluoride reacts with the silicon compound to solubilize, so that generation of scale can be easily suppressed.

According to the water treatment method of the third aspect, in addition to the effect of the water treatment method of the first or second aspect, since fluorite which contains calcium fluoride at a high degree and is easy to handle is used as the treatment material. The generation of scale can be efficiently and easily suppressed.

According to the water treatment method of the fourth aspect, in addition to the effect of the water treatment method of any one of the first to third aspects, as the water to be treated, the temperature of the water to be treated is lowered by contact with air or the like. Since groundwater for geothermal power generation containing a high concentration of an aluminosilicate, which is a silicon compound that is likely to be solidified and easily generate scale, is treated, the generation of scale during power generation can be prevented and power can be generated efficiently.

According to the water treatment method of the fifth aspect, in addition to the effect of the water treatment method of any one of the first to fourth aspects, a treatment containing a fluorine compound corresponding to the content of the silicon compound detected. Since at least one of the wavelength of the ultrasonic wave applied to the material and the time of applying the ultrasonic wave is fixedly set, generation of scale can be efficiently prevented.

According to the water treatment apparatus of the sixth aspect, ultrasonic waves are applied to the treatment material containing the fluorine compound contained in the container into which the water to be treated containing the silicon compound has flowed by the ultrasonic wave generating means, Elutes hydrogen fluoride, which is generated by the decomposition of a very small amount of fluorine compound into the water to be treated stored in the container,
Since it is solubilized by reacting with the silicon compound in the water to be treated,
The generation of scale on the downstream side can be suppressed, and the operation and treatment of the water to be treated on the downstream side can be efficiently and easily performed.

According to the water treatment apparatus of the seventh aspect, in addition to the effect of the water treatment apparatus of the sixth aspect, since the fluorine compound uses a treatment material of calcium fluoride, the fluorine compound is applied by applying ultrasonic waves. Hydrogen and calcium hydroxide are generated, calcium hydroxide is dissolved in the water to be treated, and hydrogen fluoride reacts with the silicon compound to solubilize, so that generation of scale can be easily suppressed.

According to the water treatment apparatus of the eighth aspect, in addition to the effects of the water treatment apparatus of the sixth or seventh aspect, since fluorite which contains calcium fluoride at a high degree and is easy to handle is used as the treatment material. The generation of scale can be efficiently and easily suppressed.

According to the water treatment apparatus of the ninth aspect, in addition to the effect of the water treatment apparatus of any one of the sixth to eighth aspects, as the water to be treated, the temperature of the water to be treated is lowered due to pumping or contact with air. Since groundwater for geothermal power generation containing a high concentration of an aluminosilicate, which is a silicon compound that is likely to be solidified and easily generate scale, is treated, the generation of scale during power generation can be prevented and power can be generated efficiently.

According to the water treatment apparatus of the tenth aspect, in addition to the effect of the water treatment apparatus of any one of the sixth to ninth aspects, a treatment containing a fluorine compound corresponding to the detected content of the silicon compound. Since at least one of the wavelength of the ultrasonic wave applied to the material and the time of applying the ultrasonic wave is fixedly set, generation of scale can be efficiently prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a water treatment apparatus of the present invention.

FIG. 2 is a block diagram showing the same geothermal power generation facility.

[Explanation of symbols]

 21 Main body of water treatment unit 23 Container 27 Ultrasonic generator as ultrasonic generator 28 Fluorite as treatment material

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 1/36 C02F 1/60 C02F 5/00-5/14

Claims (10)

(57) [Claims] 1. A water treatment method comprising flowing treated water containing a silicon compound into a container containing a treatment material containing a fluorine compound, and applying ultrasonic waves to the treatment material in the container. . 2. The water treatment method according to claim 1, wherein the fluorine compound is calcium fluoride. 3. The water treatment method according to claim 1, wherein the treatment material is fluorite. 4. The water treatment method according to claim 1, wherein the water to be treated is groundwater for geothermal power generation. 5. The method according to claim 1, wherein the content of the silicon compound in the water to be treated is detected, and at least one of the wavelength of the ultrasonic wave and the irradiation time is fixedly set in accordance with the detected content of the silicon compound. The method for treating water according to any one of claims 1 to 4. 6. A container for storing water to be treated containing a silicon compound so as to be able to flow in and out, a treatment material containing a fluorine compound accommodated in the container so as to be capable of being thrown in and out, and an ultrasonic wave applied to the treatment material. A water treatment apparatus, comprising: an ultrasonic wave generating means. 7. The water treatment apparatus according to claim 6, wherein the fluorine compound is calcium fluoride. 8. The water treatment apparatus according to claim 6, wherein the treatment material is fluorite. 9. The water treatment apparatus according to claim 6, wherein the water to be treated is groundwater for geothermal power generation. 10. The ultrasonic wave generating means includes a control means for fixedly setting at least one of the wavelength of the ultrasonic wave and the irradiation time in accordance with the content of the silicon compound in the water to be treated. A water treatment apparatus according to any one of claims 6 to 9.