Patent US4640825A successfully refreshed from Google Patents.
US4640825A
Expired / Lapsed
US
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Process for simultaneous removal of SO2 and NOx from gas streams
Assignee: Battelle Memorial Institute Inc
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Filing: 1985-03-26
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Granted: 1987-02-03
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Expires: 2005-03-26
Abstract
Abstract A process for simultaneous removal of SO 2 and NO x from a gas stream that includes flowing the gas stream to a spray dryer and absorbing a portion of the SO 2 content of the gas stream and a portion of the NO x content of the gas stream with ZnO by contacting the gas stream with a spray of an aqueous ZnO slurry; controlling the gas outlet temperature of the spray dryer to within the range of about a 0° to 125° F. approach to the adiabatic saturation temperature; flowing the gas, unreacted ZnO and absorbed SO 2 and NO x from the spray dryer to a fabric filter and collecting any solids therein and absorbing a portion of the SO 2 remaining in the gas stream and a portion of the NO x remaining in the gas stream with ZnO; and controlling the ZnO content of the aqueous slurry so that sufficient unreacted ZnO is present in the solids collected in the fabric filter to react with SO 2 and NO x as the gas passes through the fabric filter whereby the overall feed ratio of ZnO to SO 2 plus NO x is about 1.0 to 4.0 moles of ZnO per of SO 2 and about 0.5 to 2.0 moles of ZnO per mole of NO x . Particulates may be removed from the gas stream prior to treatment in the spray dryer. The process further allows regeneration of ZnO that has reacted to absorb SO 2 and NO x from the gas stream and acid recovery.
Inventors
- 👤 Harvey S. Rosenberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:16
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/20; C01B21/38; C01B21/40; B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/60; C01B17/00; C01B17/48; C01B17/50; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
227 words
A process for simultaneous removal of SO 2 and NO x from a gas stream comprising: a. flowing the gas stream to a spray dryer and absorbing a portion of the SO 2 content of the gas stream and a portion of the NO x content of the gas stream with ZnO by contacting the gas stream with a spray of an aqueous ZnO slurry; b. controlling the gas outlet temperature of the spray dryer to within the range of a 0° to 125° F. approach to the adiabatic saturation temperature; c. flowing the gas, unreacted ZnO and ZnO with absorbed SO 2 and NO x from the spray dryer to a fabric filter and collecting any solids therein and absorbing a portion of the SO 2 remaining in the gas stream and a portion of the NO x remaining in the gas stream with ZnO; and d. controlling the ZnO content of the aqueous slurry so that sufficient unreacted ZnO is present in the solids collected in the fabric filter to react with SO 2 and NO x as the gas passes through the fabric filter whereby the overall feed ratio of ZnO to SO 2 plus NO x is about 1.0 to 4.0 moles of ZnO per mole of SO 2 and about 0.5 to 2.0 moles of ZnO per mole of NO x .
Claim 2
Dependent Claim
227 words
A process for simultaneous removal of SO 2 and NO x from a gas stream comprising: a. flowing the gas stream to a spray dryer and absorbing a portion of the SO 2 content of the gas stream and a portion of the NO x content of the gas stream with ZnO by contacting the gas stream with a spray of an aqueous ZnO slurry; b. controlling the gas outlet temperature of the spray dryer to within the range of a 0° to 125° F. approach to the adiabatic saturation temperature; c. flowing the gas, unreacted ZnO and ZnO with absorbed SO 2 and NO x from the spray dryer to a fabric filter and collecting any solids therein and absorbing a portion of the SO 2 remaining in the gas stream and a portion of the NO x remaining in the gas stream with ZnO; and d. controlling the ZnO content of the aqueous slurry so that sufficient unreacted ZnO is present in the solids collected in the fabric filter to react with SO 2 and NO x as the gas passes through the fabric filter whereby the overall feed ratio of ZnO to SO 2 plus NO x is about 1.0 to 4.0 moles of ZnO per mole of SO 2 and about 0.5 to 2.0 moles of ZnO per mole of NO x .
Claim 3
Dependent Claim
23 words
The process of claim 1 further comprising removing particulates from the gas stream prior to flowing the gas stream to the spray dryer.
Claim 4
Dependent Claim
246 words
A process for simultaneous removal of SO 2 and NO x from a gas stream comprising: a. removing particulates from the gas stream; b. flowing the gas stream to a spray dryer and absorbing a portion of the SO 2 content of the gas stream and a portion of the NO x content of the gas stream with ZnO by contacting the gas stream with a spray of an aqueous ZnO slurry; c. controlling the gas outlet temperature of the spray dryer to within the range of a 0° to 125° F. approach to the adiabatic saturation temperature; d. flowing the gas, unreacted ZnO and ZnO with absorbed SO 2 and NO x from the spray dryer to a fabric filter and collecting any solids therein and absorbing a portion of the SO 2 remaining in the gas stream and a portion of the NO x remaining in the gas stream with ZnO; e. controlling the ZnO content of the aqueous slurry so that sufficient unreacted ZnO is present in the solids collected in the fabric filter to react with SO 2 and NO x as the gas passes through the fabric filter whereby the overall feed ratio of ZnO to SO 2 plus NO x is about 1.0 to 4.0 moles of ZnO per mole of SO 2 and about 0.5 to 2.0 moles of ZnO per mole of NO x ; and f. regenerating the ZnO having absorbed SO 2 and NO x .
Claim 5
Dependent Claim
246 words
A process for simultaneous removal of SO 2 and NO x from a gas stream comprising: a. removing particulates from the gas stream; b. flowing the gas stream to a spray dryer and absorbing a portion of the SO 2 content of the gas stream and a portion of the NO x content of the gas stream with ZnO by contacting the gas stream with a spray of an aqueous ZnO slurry; c. controlling the gas outlet temperature of the spray dryer to within the range of a 0° to 125° F. approach to the adiabatic saturation temperature; d. flowing the gas, unreacted ZnO and ZnO with absorbed SO 2 and NO x from the spray dryer to a fabric filter and collecting any solids therein and absorbing a portion of the SO 2 remaining in the gas stream and a portion of the NO x remaining in the gas stream with ZnO; e. controlling the ZnO content of the aqueous slurry so that sufficient unreacted ZnO is present in the solids collected in the fabric filter to react with SO 2 and NO x as the gas passes through the fabric filter whereby the overall feed ratio of ZnO to SO 2 plus NO x is about 1.0 to 4.0 moles of ZnO per mole of SO 2 and about 0.5 to 2.0 moles of ZnO per mole of NO x ; and f. regenerating the ZnO having absorbed SO 2 and NO x .
Claim 6
Dependent Claim
92 words
The process of claim 3 whereby the regeneration of ZnO having absorbed SO 2 and NO x further comprises: a. collecting the reacted ZnO having absorbed SO 2 and NO x from the fabric filter; b. calcining the reacted ZnO from step a to decompose the reacted ZnO to ZnO, SO 2 , NO, and NO 2 ; c. cooling, classifying and grinding the ZnO obtained from step b; and d. mixing the ZnO from step c with water to produce an aqueous ZnO slurry suitable for use in the spray dryer.
Claim 7
Dependent Claim
27 words
The process of claim 4 further comprising: feeding the SO 2 , NO, and NO 2 to an acid plant for conversion to sulphuric and nitric acid.
Claim 8
Dependent Claim
24 words
The process of claim 3 further comprising: injecting saturated steam into the gas stream prior to flowing the gas stream to the spray dryer.
Claim 9
Dependent Claim
23 words
The process of claim 3 further comprising: extracting heat from the gas stream prior to flowing the gas stream to the spray dryer.
Claim 10
Dependent Claim
29 words
The process of claim 3 further comprising: operating the spray dryer at a 0° F. approach to saturation and reheating the flowing gas stream prior to the fabric filter.
Claim 11
Dependent Claim
23 words
The process of claim 3 further comprising: injecting steam into the gas stream prior to flowing the gas stream to the fabric filter.
Claim 12
Dependent Claim
30 words
The process of claim 3 further comprising adding silica gel to the aqueous ZnO slurry within a weight ratio range of silica gel to ZnO of about 1:10 to 1:1.
Claim 13
Dependent Claim
16 words
The process of claim 3 further comprising oxidizing NO to NO 2 in an oxidation chamber.
Claim 14
Dependent Claim
33 words
The process of claim 3 further comprising controlling SO 2 removal in the spray dryer so that the SO 2 can have a synergistic effect no NO x removal in the fabric filter.
Claim 15
Dependent Claim
39 words
The process of claim 4 further comprising adding one-half mole carbon per mole of zinc sulfate after step a and prior to calcining to lower the decomposition temperature of zinc sulfate and operating the calciner at the lower temperature.
Claim 16
Dependent Claim
37 words
The process of claim 4 further comprising extracting the zinc sulfate with water after step a and prior to the calcination step and performing the calcination step (b) at a temperature between about 450° to 550° F.
Claim 17
Dependent Claim
37 words
The process of claim 4 further comprising performing the calcination step (b) at a temperature between about 450° to 55° F. whereby the zinc sulfate is allowed to reach a steady state concentration in the recycled solids.
Claim 18
Dependent Claim
17 words
The process of claim 4 further comprising operation step (b) at a calcination temperature of 1400° F.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |