EP0380299A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of improving langelier index of city water and an apparatus therefor
Assignee: Kureha Corp
•
Filing: 1990-01-23
•
Granted: —
•
Expires: 2010-01-23
Abstract
Abstract A method is disclosed for reducing the corrosiveness of a water supply, and preventing the generation of red water caused by iron rust, by modifying the Langelier index of the water, which comprises: (1) determining the amount of carbon dioxide required to increase the concentration of free carbonic acid in the water based on the existing and desired Langelier indices, and the acceptable pH range, of the water supply; (2) dissolving the said amount of carbon dioxide gas in the water to generate free carbonic acid in the water; and (3) adding a substantially saturated aqueous solution of slaked lime to the water supply such that the free carbonic acid is neutralised and the desired Langelier index is achieved. An apparatus for carrying out the method is also disclosed.
Inventors
- 👤 Isao Funahashi
- 👤 Kiwamu Yamamoto
- 👤 Shinichi Kuboki
- 👤 Masahiro Hiruta
- 👤 Hideo Abe
- 👤 Moritoshi Ono
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 00:41
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/66; C23; C23F; C23F15/00; C02F1/68; C02F5/00; C02F5/02; C02F2303/00; C02F2303/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
103 words
A method of treating water to achieve a desired Langelier index in a water supply which comprises: (1) determining the amount of carbon dioxide required to increase the concentration of free carbonic acid in the water based on the existing and desired Langelier indices, and the acceptable pH range, of the water supply; (2) dissolving the said amount of carbon dioxide gas in the water to generate free carbonic acid in the water; and (3) adding a substantially saturated aqueous solution of slaked lime to the water supply such that the free carbonic acid is neutralised and the desired Langelier index is achieved.
Claim 2
Independent Claim
103 words
A method of treating water to achieve a desired Langelier index in a water supply which comprises: (1) determining the amount of carbon dioxide required to increase the concentration of free carbonic acid in the water based on the existing and desired Langelier indices, and the acceptable pH range, of the water supply; (2) dissolving the said amount of carbon dioxide gas in the water to generate free carbonic acid in the water; and (3) adding a substantially saturated aqueous solution of slaked lime to the water supply such that the free carbonic acid is neutralised and the desired Langelier index is achieved.
Claim 3
Dependent Claim
59 words
A method according to claim 1, wherein the pH of the water containing free carbonic acid or of the water after addition of the solution of slaked lime is detected and a corresponding signal produced, said signal being supplied to a device controlling the flow rate of the substantially saturated aqueous solution of slaked lime into the water supply.
Claim 4
Dependent Claim
42 words
A method according to claim 1 or 2, wherein the flow rate of the water containing free carbonic acid produced in step (2) is detected and a corresponding signal produced, said signal being supplied to a carbon dioxide gas flow rate controller.
Claim 5
Dependent Claim
20 words
A method according to claim 1, 2 or 3, wherein the said desired Langelier index is from -1 to +1.
Claim 6
Independent Claim
31 words
A method according to any one of the preceding claims wherein the starting content of free carbonic acid in the water supply to be treated is not higher than 20 ppm.
Claim 7
Independent Claim
29 words
A method according to any one of the preceding claims, wherein the content of slaked lime in the said substantially saturated aqueous solution is from 1,550 to 1,650 ppm.
Claim 8
Independent Claim
14 words
A method according to any one of the preceding claims which is operated continuously.
Claim 9
Independent Claim
77 words
An apparatus for use in treating water to achieve a desired Langelier index of a water supply by addition of gaseous carbon dioxide and a substantially saturated slaked lime solution, which comprises a means for detecting the pH of the water after one or both of these additives has been added and a means for controlling the rate of flow of the substantially saturated slaked lime solution into the water supply in accordance with the detected pH.
Claim 10
Independent Claim
77 words
An apparatus for use in treating water to achieve a desired Langelier index of a water supply by addition of gaseous carbon dioxide and a substantially saturated slaked lime solution, which comprises a means for detecting the pH of the water after one or both of these additives has been added and a means for controlling the rate of flow of the substantially saturated slaked lime solution into the water supply in accordance with the detected pH.
Claim 11
Dependent Claim
54 words
An apparatus according to claim 8 including a means for detecting the flow rate of the water to which the gaseous carbon dioxide has been added and a means for controlling the rate of flow of the gaseous carbon dioxide into the water in accordance with a signal provided thereto by said detecting means.
Claim 12
Dependent Claim
61 words
An apparatus according to claim 8 or 9 comprising a slaked lime dissolving vessel, a carbon dioxide gas dissolving vessel, and a slaked lime addition portion or addition vessel in which a substantially saturated aqueous solution of slaked lime from the slaked lime dissolving vessel is added to water containing free carbonic acid produced in the carbon dioxide gas dissolving vessel.
References Cited (Backward Citations)
FR2376079A1
Cited
FR2616451A1
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.