US4669530A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat exchanger method and apparatus
Assignee: POWER EQUIPMENT SYSTEMS Inc dba CONDENSING HEAT EXCHANGER
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Filing: 1985-12-19
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Granted: 1987-06-02
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Expires: 2005-12-19
Abstract
Abstract An exhaust gas containing sulfur trioxide is passed through a first heat exchanger which cools the gas to a temperature which is above the sulfur trioxide dewpoint, so that condensation of sulfur trioxide does not occur in the first heat exchanger, but below a material limit operating temperature of a second heat exchanger, which further cools the gas below the sulfur trioxide dewpoint, whereby the first heat exchanger is protected against corrosion and the second heat exchanger is protected against thermal damage.
Inventors
- 👤 Donald F. Warner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:54
CPC Classifications
F; F28; F28D; F28D21/00; F28D21/0001; F28D21/0003; F28D21/001; B; B01; B01D; B01D53/00; B01D53/002; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/507; F23; F23J; F23J15/00; F23J15/06; F28D7/00; F28D7/08; F28D7/082; F28D7/085; F28D7/16; F28D7/1615; F28D7/1623; F28F; F28F19/00; F28F19/02; F28F19/04; F28F9/00; F28F9/007; F28F9/013; F28F9/0131; Y; Y02; Y02E; Y02E20/00; Y02E20/30; Y10; Y10S; Y10S165/00; Y10S165/909
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
203 words
The method of recovering heat energy from an exhaust gas containing a corrosive constituent which is condensable at and below a corrosive condensation temperature by passing said gas successively through first and second heat exchangers each connected to transfer heat to a fluid, said second heat exchanger containing corrosion-protection exterior tube-coverings having a material limit operating temperature exceeding said corrosive condensation temperature, the flow rates and temperatures of said exhaust gas and the fluid being heated by each heat exchanger being arranged so that passage of said exhaust gas through said first heat exchanger cools said exhaust gas from a first temperature exceeding said material limit operating temperature to a second temperature which is below said material limit operating temperature but above said corrosive condensation temperature, and passage of said exhaust gas through said second heat exchanger cools at least a portion of said exhaust gas from a temperature above said corrosive condensation temperature to a temperature below said corrosive condensation temperature whereby said corrosive constituent does not condense in said first heat exchanger, said corrosive constituent does condense in said second heat exchanger, and the cooling of said gas in said first heat exchanger prevents thermal damage to said second heat exchanger.
Claim 2
Independent Claim
203 words
The method of recovering heat energy from an exhaust gas containing a corrosive constituent which is condensable at and below a corrosive condensation temperature by passing said gas successively through first and second heat exchangers each connected to transfer heat to a fluid, said second heat exchanger containing corrosion-protection exterior tube-coverings having a material limit operating temperature exceeding said corrosive condensation temperature, the flow rates and temperatures of said exhaust gas and the fluid being heated by each heat exchanger being arranged so that passage of said exhaust gas through said first heat exchanger cools said exhaust gas from a first temperature exceeding said material limit operating temperature to a second temperature which is below said material limit operating temperature but above said corrosive condensation temperature, and passage of said exhaust gas through said second heat exchanger cools at least a portion of said exhaust gas from a temperature above said corrosive condensation temperature to a temperature below said corrosive condensation temperature whereby said corrosive constituent does not condense in said first heat exchanger, said corrosive constituent does condense in said second heat exchanger, and the cooling of said gas in said first heat exchanger prevents thermal damage to said second heat exchanger.
Claim 3
Dependent Claim
36 words
The method of claim 1 wherein said exhaust gas comprises flue gas containing water vapor and said corrosive constituent comprises sulfur trioxide, whereby passage of said exhaust gas through said second heat exchanger produces sulfuric acid.
Claim 4
Dependent Claim
40 words
The method of claim 1 wherein the step of passing said exhaust gas through said second heat exchanger comprises passing said exhaust gas in heat exchange relationship generally perpendicularly to and between generally horizontally extending tubes of a tube nest.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein said corrosion-protection material comprises a fluoroplastic.
Claim 6
Dependent Claim
34 words
The method of claim 1 which includes the step of passing the fluid to be heated by said second heat exchanger through metal tubes in said second heat exchanger having said exterior tube coverings.
References Cited (Backward Citations)
US2801830A
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Cited
GB1042386A
Cited
GB1042387A
Cited
US3556207A
Cited
FR2286359A1
Cited
FR2331763A1
Cited
US4193180A
Cited
US4296804A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-01 | 1990-12-01 | 1991-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-01 | 1994-12-01 | 1995-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-01 | 1998-12-01 | 1999-06-02 | $7700.00 | Window Closed / Lapsed |