Method and apparatus for detecting concentration of solution, and apparatus for diluting and preparing agents

• US 20010031501A1
• Filed: 03/15/2001
• Published: 10/18/2001
• Est. Priority Date: 03/15/2000
• Status: Active Grant

• Current Assignee: Kanto Kagaku Kabushiki Kaisha
• Original Assignee: Kanto Kagaku Kabushiki Kaisha
• Inventors: Nomura, Akio, Iwao, Tomoaki
• Granted Patent: US 6,706,533 B2
• Time in Patent Office: Days
• US Class Current: 436/149
• CPC Class Codes: G01N 27/06 of a liquid involving electrolysis G01N27/26
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/25625 Dilution

Abstract

A concentration detection method and a concentration detection apparatus, and an agent diluting preparation apparatus capable of accurately estimating the concentration of a solution without the need of strict temperature control, and of estimating the concentration of the solution in real time, and further of cost reduction of diluting and preparing an agent and of simplification of diluting and preparing work are provided herein.

Claims

1. A method for detecting a concentration of a solution comprising a step of measuring an electrical conductivity and a temperature of a solution and a step of calculating a concentration of a desired substance in the solution, wherein the calculation of the concentration is achieved on the basis of the following formula:

C=(D−

aT−

b)/AT+B 

 

(1)

wherein C is the concentration of a desired substance, D is the electrical conductivity of the solution at the temperature T, T is the temperature of the solution, and A, B, a, and b indicate constants.

2. The method for detecting a concentration of

claim 1

, wherein the constants A, B, a, and b in the formula 1 are values which are obtained by measuring the electrical conductivities at a plurality of temperatures for each of solutions containing the same desired substances with a plurality of concentrations and estimating the values with the least squares method.

3. The method for detecting a concentration of

claim 1

or

2

, wherein the constants A, B, a, and b are values estimated by a method including

a first step for measuring an electrical conductivity at a plurality of temperatures for each of solutions each containing the same agents with a plurality of concentrations,

a second step for deriving a linear equation using the least squares method for a relationship between the temperature and the electrical conductivity at each concentration,

a third step for calculating the electrical conductivity at each temperature by substituting the plurality of the temperatures for each of said linear equation,

a fourth step for deriving a linear equation with the least squares method with respect to the electrical conductivity and the concentration at each temperature in the third step, and

a fifth step for deriving linear equations, w=AT+B and z=aT+b, depending upon temperature with respect to each of the inclination w and the intercept z of each linear equation obtained in the fourth step.

4. The method for detecting a concentration of

claim 1

or

2

, wherein the plurality of the temperatures is included in a temperature range of ±

5 degrees of a desired temperature.

5. The method for detecting a concentration of

claim 1

or

2

, wherein the plurality of the temperatures are included in the temperature range of ±

10 degree of a desired temperature.

6. The method for detecting a concentration of

claim 1

,

2

, 3, 4 or 5, wherein the solution is an aqueous solution.

7. The method for detecting a concentration of any of

claims 1

to

6

, wherein the solution contains only one kind of a solute.

8. A method for diluting and preparing an agent to a desired concentration utilizing the method for detecting a concentration of any of

claims 1

to

7

.

9. The method for diluting and preparing an agent of

claim 8

, which comprising

a first step for mixing the agent with water into a aqueous solution thereof,

a second step for detecting a concentration of the agent in the aqueous solution, and

a third step for adding an agent or water into the aqueous solution to adjust the concentration of the agent to a desired concentration based upon the detected concentration of the agent.

10. The method for diluting and preparing an agent of

claim 9

, wherein at least the second step and the third step are controlled with a computer program.

11. A concentration detecting apparatus comprising electric conductivity measuring means and arithmetic operation means, wherein a concentration of a desired substance in a solution is detected by the arithmetic operation means based upon temperature and an electric conductivity and temperature of the solution measured by the electric conductivity measuring means, wherein the arithmetic operation means calculates the following equation:

C=(D−

aT−

b)/(AT+B) 

 

(1)

wherein, C is the concentration of a desired substance, D is the electric conductivity of the solution at temperature T, T is temperature of the solution, and A, B, a, and b denote constants.

12. The concentration detecting apparatus of

claim 11

, wherein the constants A, B, a, and b in the formula 1 are values which are obtained by measuring the electrical conductivities at a plurality of temperatures for each of solutions containing the same desired substances with a plurality of concentrations and estimating the values with the least squares method.

13. The concentration detecting apparatus of

claim 11

or

12

, wherein the constants A, B, a, and b are values estimated by a method including

a first step for measuring an electrical conductivity at a plurality of temperatures for each of solutions each containing the same agents with a plurality of concentrations,

a second step for deriving a linear equation using the least squares method for a relationship between the temperature and the electrical conductivity at each concentration,

a third step for calculating the electrical conductivity at each temperature by substituting the plurality of the temperatures for each of said linear equation,

a fourth step for deriving a linear equation with the least squares method with respect to the electrical conductivity and the concentration at each temperature in the third step, and

a fifth step for deriving linear equations, w=AT+B and z=aT+b, depending upon temperature with respect to each of the inclination w and the intercept z of each linear equation obtained in the fourth step.

14. The concentration detection apparatus of

claim 11

or

12

, wherein the plurality of the temperatures is included in a temperature range of ±

5 degrees of a desired temperature.

15. The concentration detection apparatus of

claim 11

or

12

, wherein the plurality of the temperatures is included in a temperature range of ±

10 degrees of a desired temperature.

16. The concentration detection apparatus of

claim 11

,

12

, 13, 14 or 15, wherein the solution is an aqueous solution.

17. The concentration detection apparatus of any of

claims 11

to

16

, wherein the solution contains only one kind of a solute.

18. The concentration detection apparatus of any of

claims 11

to

17

, wherein the electric conductivity measuring means includes a measuring chamber equipped with an inlet for aqueous solution and an outlet at a head thereof, and a horizontal cross section of the measuring chamber is continuously reduced toward the outlet for aqueous solution.

19. The concentration detection apparatus of

claim 18

, wherein the measuring chamber has a measuring rod and further another inlet for aqueous solution, wherein the measuring rod is disposed in the measuring chamber and has a through-hole therein, the further another inlet for aqueous solution is in the vicinity of an intersection between an extension line of the through-hole and a wall surface of the measuring chamber.

20. An agent diluting preparation apparatus, including the concentration detection apparatus according to any one of

claims 11

to

19

, wherein an agent is mixed with water and is prepared to a desired concentration.

21. The agent diluting preparation apparatus of

claim 20

, comprising a diluting preparation tank, mixing means for mixing an agent with water into an aqueous solution, and concentration adjusting means for adding an agent or water to the aqueous solution based upon the detected concentration and adjusting the concentration of the agent to a desired concentration.

22. The agent diluting preparation apparatus of

claim 21

, wherein at least the concentration detection apparatus and the concentration adjusting apparatus are controlled with a computer program.

23. The agent diluting preparation apparatus of

claim 21

or

22

, wherein a part of the aqueous solution is tentatively sent from the diluting preparation tank to the electric conductivity measuring means of the concentration detection apparatus when the electric conductivity and temperature are measured, wherein the electric conductivity measuring means includes a measuring chamber having an inlet for aqueous solution and an outlet for aqueous solution at the head thereof, and a horizontal cross section of the measuring chamber is continuously reduced toward the outlet for aqueous solution.

24. The agent diluting preparation apparatus of

claim 23

, wherein the measuring chamber has a measuring rod and further another inlet for aqueous solution, wherein the measuring rod is disposed in the measuring chamber and has a through-hole therein, the further another inlet for aqueous solution is in the vicinity of an intersection between an extension line of the through-hole and a wall surface of the measuring chamber.