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Patent US4022639A successfully refreshed from Google Patents.
US4022639A
Expired / Lapsed
US
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Method for removing carbon scale
Assignee: Kurita Water Industries Ltd
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Filing: 1975-07-10
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Granted: 1977-05-10
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Expires: 1995-07-10
Abstract
Abstract A method for removing carbon scale, comprising permeating carbonate or bicarbonate into the carbon scale formed on a metal surface of a heating furnace, reactor or the like in a chemical plant by bringing the former into contact with the latter and decomposing the thus treated scale through oxidation by applying heat.
Inventors
- 👤 Hiroshi Ueki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:14
CPC Classifications
C; C23; C23G; C23G5/00; B; B08; B08B; B08B3/00; B08B3/04; B08B3/08; B08B3/10; B08B7/00; B08B7/0064; B08B7/0071; B08B7/04; F; F23; F23J; F23J3/00; F23J3/02
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
136 words
A method for removing adherent carbon-containing scale from an object, which consists essentially of the steps of: contacting said scale with a 0.1 to 20 weight percent aqueous solution of a substance selected from the group consisting of ammonium carbamate and sodium, potassium, silver, ammonium and amine carbonates and bicarbonates, for a first period of time effective to permeate said solution into said scale; then removing the remaining solution from contact with said scale; then heating the scale to a temperature in the range of from 200° to 500° C and simultaneously circulating past said scale and in contact therewith a stream of air or gaseous oxygen, for a second period of time effective to oxidize the carbon in said scale and to transform it to a gas so that it is removed from said object.
Claim 2
Independent Claim
136 words
A method for removing adherent carbon-containing scale from an object, which consists essentially of the steps of: contacting said scale with a 0.1 to 20 weight percent aqueous solution of a substance selected from the group consisting of ammonium carbamate and sodium, potassium, silver, ammonium and amine carbonates and bicarbonates, for a first period of time effective to permeate said solution into said scale; then removing the remaining solution from contact with said scale; then heating the scale to a temperature in the range of from 200° to 500° C and simultaneously circulating past said scale and in contact therewith a stream of air or gaseous oxygen, for a second period of time effective to oxidize the carbon in said scale and to transform it to a gas so that it is removed from said object.
Claim 3
Dependent Claim
18 words
A method according to claim 1, wherein said first period of time is from 1 to 48 hours.
Claim 4
Dependent Claim
18 words
A method according to claim 1, wherein said first period of time is from 6 to 48 hours.
Claim 5
Dependent Claim
14 words
A method according to claim 1, wherein said solution contains a surface active agent.
Claim 6
Dependent Claim
29 words
A method according to claim 1 including the step of circulating superheated steam into contact with said scale simultaneously with the circulation of the stream of air or oxygen.
Claim 7
Dependent Claim
17 words
A method according to claim 1, wherein said substance is sodium, potassium, silver, ammonium or amine carbonate.
Claim 8
Dependent Claim
15 words
A method according to claim 1, wherein said substance is sodium, potassium or ammonium carbonate.
Claim 9
Dependent Claim
18 words
A method according to claim 1, wherein said second period of time is from 1 to 24 hours.
Claim 10
Dependent Claim
18 words
A method according to claim 1, wherein said second period of time is from 5 to 24 hours.
Claim 11
Dependent Claim
23 words
A method according to claim 1, wherein said scale is heated at a temperature in the range of from 250° to 450° C.
Claim 12
Dependent Claim
25 words
A method according to claim 1, wherein the scale is a carbon scale formed in the reactor and/or the furnace of a naptha cracking system.
Claim 13
Dependent Claim
83 words
A method according to claim 1 wherein said scale is heated at about 50° to 80° C when it is contacted by said solution, said solution contains from 5 to 10 weight percent of said substance, said substance is selected from the group consisting of sodium carbonate, potassium carbonate and ammonium carbonate, said first period of time is from 6 to 48 hours, said second period of time is from 5 to 24 hours, and said temperature is from 250° to 450° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-09 | 1980-11-08 | 1981-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-09 | 1984-11-08 | 1985-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-09 | 1988-11-08 | 1989-05-10 | $7700.00 | Window Closed / Lapsed |