JPS63141696A - Production of mineralized water - Google Patents

Abstract

PURPOSE:To attain a prescribed saturation index by measuring the temp. pH value, Ca concn. and dissolved carbon dioxide concn. of mineralized water, calculating the saturation index and/or stability index thereof and subjecting an aq. alkaline soln. to injection control. CONSTITUTION:Gaseous CO2 is injected to pure water in a 1st stage. The water is brought into contact with a Ca-contg. material to form the water contg. Ca<2+> ion and HCO3<-> ion in a 2nd stage. The aq. alkaline water is injected to the water in a 3rd stage. The pH value of the water obtd. in the 2nd stage is measured and the injection rate of the gaseous CO2 is adjusted at this time. The temp., pH value, Ca concn. and dissolved carbon dioxide concn. of the water obtd. in the 3rd stage are measured and the saturation index and/or stability index are computed. The injection rate of the aq. alkaline soln. is thereby controlled so as to have the saturation index and/or stability index within the prescribed range. Ca<2+> and HCO3<-> are dissolved in the pure water to about the extent considered to be saturation or slightly supersaturation to maintain the less corrosive condition in this method.

Description

Detailed Description of the Invention Field of Industrial Application: The present invention involves dissolving Ps in pure water by dissolving calcium, magnesium, alkali metals, etc. in the form of carbonates, acidic carbonates, etc.
The present invention relates to a method for producing mineral water.

Here, pure water refers to water purified by a distillation method (including normal distillation method and flash distillation method), reverse osmosis method, etc., and mineral water refers to water containing inorganic components.

・R-scape technology: Pure water is tasteless and undesirable as a beverage. In addition, steel pipes
When transporting in steel containers, iron tends to become m4, so the rate of thinning is fast, and water tends to turn red. Even when it is used as a material for metal, U, or containers such as concrete or asbestos, soluble components tend to leach out and the durability deteriorates.

In order to prevent this drawback, conventionally, after injecting 002 gas into pure water, it is brought into contact with granular solids (curing agent) such as limestone, dolphite, etc. containing 7I fulsium carbonate and magnesium carbonate, and the Ca is extracted as a main body of gold. , then further,
Aqueous solutions (alkaline agents) such as NaOH, Ca(OH)2, etc.
A method was known for adjusting the pH of treated water by adding (described in Japanese Patent Publications No. 61-572j2, No. 61-57293, No. 61-97098, etc.).

Also, Larson La (Journal-Amer
ican Waterworks As5ociati
on, Vol -84+ 1667 + 1944
), f(20ヰHゝ+Od−・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・(1) KW = (
)f"X0f(-), Kw' = (:)I")
(OH-)CO, +H20=M, Co8=H” 10H
co; --------old・-・-(2)HCO,;
= H" + CO knee Shouting, group, old... old old old old... (3) However, [] represents activity, and [] represents concentration θ. Debye is used to estimate the activity coefficient.
- Huckel J) % Using the a law, the pH of a state saturated with calcium carbonate (!
1og(alk) +9.80+(2,5 car)/(1
+5.8σ+5.5μ) ・・・・・・・・・(4)
However, μ indicates ionic strength, and alk is alkalinity (total alkalinity, M alkalinity) defined by equation (5), which is a value that can be measured using methyl orange as an indicator.

(a l k) + (H”) = 2(CO knee
, l + (HCOa) + (OH-]・” (5
) However, (Ca) is a ppm value expressed as Ca, and (alk, ] is a ppm value expressed as CtCOa.

Table 1 shows the values of 1, KW, and K8 in 4 above.

Table 1 Saturation index (Langellier index) L-1, is (p
Ha-pds), safety index (dyzner index) S
, 1. (2P.

-pHa) and is considered to be useful from the perspective of scale formation and equipment corrosion (gyzner: Jour
nal-American water works
As5ocation, Vo135.

P, 472-486, 1944).

Now, the above-mentioned 9 mineralized water is desirable.■.

In order to maintain the value, S, and I value, there is a method of injecting COz gas into pure water, measuring the dissolved CO2, and controlling this measured value and the desired reference value by 11tlI. 57
No. 292 and No. 61-57298, and a method of measuring the conductivity of produced mineralized water and controlling it to a desired value is known (Japanese Patent Laid-Open No. 61-46298).
.

Problem to be solved: However, when injected into pure water, the solution of CO2 in the bath ((2
)2K Necessary'k CO2 (!: Excess gJIJCO2t t tro ) (D The tau constant value has the disadvantage of being unstable, and the method of measuring the rinsing conductivity of mineralized water has the disadvantage that the temperature dependence of the conductivity is The dog must be used to compensate for the temperature.

Means for solving the problem: In the non-invention, the first step is to inject CO2 gas into pure water,
The water containing CO2 obtained in the first step is brought into contact with a calcium-containing substance, and Ca! “Ions and aCO: A method for producing mineralized water consisting of a second step of making water containing ions, and a third step of injecting an alkaline aqueous solution into the water obtained in the second step. The pH of the water obtained in
The step of adjusting the injection amount of CO and gas by measuring The method is characterized in that the injection amount of the alkaline aqueous solution is controlled to be in the range of a predetermined saturation index 2 and/or stability I\Ia by calculating a stability index. temperature of mineralized water,
Measure the pH value, calcium concentration, and dissolved carbon dioxide concentration, and first calculate nco8@degree by automatic calculation, pHs=log(Ks/Kg)−1og(Ca)−
1og(f(CO; J+ 9.80 + 2.5σ/(
1+5.3σ-5,5μ)・・・・・・(6)((6)
In the formula, KSl is 2, [Ca2+], and μ are as shown in formula (4): (HCO;) is expressed as ppm CaCO3, where 2 ion moles of UCO; are 1 mole of CaCOB.
CO; concentration), pf(s) was calculated, and the measured pH value (expressed in pHa).

) The relationship is the saturation index (pHa - p) is ) =
Q-0,5 power tuna constant index (2pH5-pHa)
The amount of the alkaline aqueous solution added is adjusted so that the ratio is 6 to 7.

Effect: The structure of the present invention is as described in the above-mentioned JP-A-61-57292 and JP-A-61-57292.
The CO2 detection position is different from that described in Japanese Patent No. 1-57298. That is, in the method described in the same publication, CO2 is measured at a position upstream from the calcium dissolution tank, whereas in the present invention, pH is measured at a position downstream from the calcium dissolution tank.

An example of the results of examining the correlation between the amount of carbon dioxide gas injected and the pi value in mineralized water using a test device is shown in Table 2.

Table 2, namely CO! Adjustment is possible because there is an inverse relationship between injection temperature and pH value.

Next, we will discuss the reason for changing equation (4) to equation (6), that is, [
The reason for changing alk) to (HCO;) is p)I
= 7 to 8.5 (therefore, when the alkalinity using phenolphthalene as an indicator, that is, the P alkalinity is zero), the alkalinity referred to in this specification J (alkalinity using methylnadi as an indicator, M alkalinity) ) is the same as f(Co; (expressed as ppm CaCO3). Table 3 shows P alkalinity, M alkalinity, (oH-), (Coney, l, (t
Indicates the relationship between [X)-.

isa table In the present invention, the pH is valid in the range of 7 to 8.5, so the P alkalinity in the above table = O, that is, the alkalinity is all HC
L).

Further, (f(CO;) can be obtained by measuring CO2# degree and calculating rζ from equation (2).

-Also, the CO2 concentration in water can be easily determined using the 1IA electrode method, and commercially available products are sufficient for use. C
a The measurement is carried out using an ion AMLC, and a commercially available one is sufficient.

Example: In the example shown in FIG. 1, pure water is first injected with CO2 gas supplied from a CO2 gas source, and then reaches the calcium dissolution tower to form H2O+ CO2+ CaCOB = Ca '' +
Bile; ...""..."" Dissolves by the reaction represented by (7) (referred to as hardening reaction).

The reactions that take place in the calcium dissolution tank (7) generally do not terminate and the CO2 remains in dissolved form in the water and the pH
Since it lowers the alkaline rostral Na0) I, C
a(OH) 2 fl Which water? Add Il'[ to raise the PH to the desired value. In the figure, (1) is the alkaline aqueous solution inlet, (2) is the mineralized water pi (measuring unit, and at the ninth stage when the measured pH is set to a predetermined value, for example 8, the f14 control valve (3) is automatically operated. The amount of alkaline aqueous solution fed at position ffi (1) is adjusted to 1. Ca in the water that has been treated in the calcium dissolution tower (5) is sampled at position (4), and the pH is measured and brought close to the desired value. For this purpose, the automatic control valve (5) is automatically operated.In addition, the total amount of carbon dioxide in the water sampled at position (4) is automatically measured separately, and L, 1.
,S,1. It is used in the calculation of 1. , S・engineering is used to determine the control objective value.

A convenient calcium dissolution tower is one with a packed tower structure using calcium-containing particles such as limestone or dolomite as a filler.
The flow of water may be from above to below or from below to above.

Effects of the invention: In the method for producing mineralized water of the present invention, pure water contains Ca'' and HCOH to an extent that is considered to be saturated or slightly supersaturated (
L, I.=θ~0.5), and can be operated so as to maintain a less corrosive state d(S, 1.=6~8). Therefore, there is an advantage that [Ca] and (Heo;) can be easily and continuously measured. Therefore, it is suitable for wide general use and has great industrial applicability.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the invention shown as a flowchart, with instrumentation automation applied. A... Calcium dissolution tank

Claims (1)

[Claims] 1. A first step of injecting CO_2 gas into pure water, and bringing the water containing CO_2 obtained in the first step into contact with a calcium-containing substance to form Ca^2^+ ions and HCO^-. _3 A method for producing mineralized water comprising a second step of making water containing ions and a third step of injecting an alkaline aqueous solution into the water obtained in the second step, Measuring the pH value of water and CO_2
adjusting the amount of gas to be injected, and calculating the saturation index and/or stability index by measuring the temperature, pH value, calcium concentration, and dissolved carbon dioxide concentration of the water obtained in the third step. A method for producing mineralized water, comprising controlling the injection amount of the alkaline aqueous solution so that it falls within a predetermined saturation index and/or stability index range.