US4696805A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for desulfurizing exhaust gas
Assignee: Mitsubishi Heavy Industries Ltd
•
Filing: 1986-01-23
•
Granted: 1987-09-29
•
Expires: 2006-01-23
Abstract
Abstract Here are disclosed a method for desulfurizing an exhaust gas which is characterized by comprising a gas absorbing section in which an absorbing solution absorbs SO 2 in the exhaust gas in order to become an acid solution containing a sulfite; an oxidizing section in which the sulfite is oxidized; a neutralizing section in which the absorbing solution is neutralized by adding an SO 2 absorbent; and a closed circulating circuit for delivering the solution drawn out from the gas absorbing section to the oxidizing section, delivering the solution drawn out from the oxidizing section to the neutralizing section, and delivering the solution drawn out from the neutralizing section to the gas absorbing section; and a method for simultaneously treating SO 2 and HCl which the abovementioned exhaust gas contains.
Inventors
- 👤 Naoharu Shinoda
- 👤 Atsushi Tatani
- 👤 Masakazu Onizuka
- 👤 Susumu Okino
- 👤 Taku Shimizu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:52
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501; B01D53/68
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
154 words
A method for simultaneously treating SO 2 and HCl comprising passing said gas through a gas absorbing solution which absorbs SO 2 and HCl to produce an acid solution containing a sulfite and a chloride; and oxidizing section in which said sulfite is oxidized by blowing air into said absorbing solution to oxidize said sulfite; neutralizing said absorbing solution by adding a compound selected from the group consisting of CaCO 3 and Ca(OH) 2 ; said gas absorbing solution being passed through a closed circulating circuit for delivering said solution from said gas absorbing section to said oxidizing section, delivering said solution drawn out from said oxidizing section to said neutralizing section, and delivering said solution drawn out from said neutralizing section to said gas absorbing section; and recovering gypsum as a by-product from said absorbing solution in said closed circulating circuit; said chloride being taken out in the form of an aqueous solution.
Claim 2
Independent Claim
154 words
A method for simultaneously treating SO 2 and HCl comprising passing said gas through a gas absorbing solution which absorbs SO 2 and HCl to produce an acid solution containing a sulfite and a chloride; and oxidizing section in which said sulfite is oxidized by blowing air into said absorbing solution to oxidize said sulfite; neutralizing said absorbing solution by adding a compound selected from the group consisting of CaCO 3 and Ca(OH) 2 ; said gas absorbing solution being passed through a closed circulating circuit for delivering said solution from said gas absorbing section to said oxidizing section, delivering said solution drawn out from said oxidizing section to said neutralizing section, and delivering said solution drawn out from said neutralizing section to said gas absorbing section; and recovering gypsum as a by-product from said absorbing solution in said closed circulating circuit; said chloride being taken out in the form of an aqueous solution.
Claim 3
Dependent Claim
71 words
A method according to claim 2 wherein at least one selected from the group consisting of Na + , K + , Mg 2+ and NH 4 + is contained in the absorbing solution in an amount of one equivalent or more of a Cl concentration in said absorbing solution, and said chloride is taken out in the form of an aqueous solution of a different chloride than a calcium compound.
Claim 4
Dependent Claim
25 words
A method according to claim 1 or 2 wherein a manganese compound is added, as an oxidizing accelerator for said sulfite, to said absorbing solution.
Claim 5
Dependent Claim
30 words
A method according to claim 1 or 2 wherein a concentration of CaCO 3 in said absorbing solution in said neutralizing section is adjusted to less than 2% by weight.
Claim 6
Dependent Claim
54 words
A method according to of claim 1 or 2 wherein in order to recover gypsum as a by-product, a part of said absorbing solution is drawn out from said oxidizing step, and an aqueous chloride solution is taken out from a part of said absorbing solution in said oxidizing step or said neutralizing step.
Claim 7
Dependent Claim
26 words
A method according to claim 1 or 2 wherein the chloride is recovered in the form of a solid chloride by concentrating said aqueous chloride solution.
References Cited (Backward Citations)
US3904742A
Cited
DE2532373A1
Cited
DE2541821A1
Cited
US3985860A
Cited
US4328195A
Cited
US4539190A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-09-28 | 1991-03-30 | 1991-09-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-09-28 | 1995-03-30 | 1995-09-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-09-28 | 1999-03-30 | 1999-09-29 | $7700.00 | Window Closed / Lapsed |