Patent US3638622A successfully refreshed from Google Patents.
US3638622A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Return flow boiler
Assignee: Goetaverken Angteknik AB
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Filing: 1970-04-06
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Granted: 1972-02-01
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Expires: 1990-04-06
Abstract
Abstract In return flow boilers the gases flowing along the wall of the flue tube will be cooled, whereby the combustion in the marginal portions of the flame will be considerably less complete than in the core thereof, which will have undesirable consequences when the flame emerges into the return chamber. In order to bring about a complete combustion also of the marginal portions of the flame the outlet of the flue tube is considerably restricted as compared to the main part of the tube, whereby the portions of the flame having flown along the wall of the flue tube will be forced into the core of the flame, when this emerges into the return chamber.
Inventors
- 👤 Nils Axel Ambjorn Ostbo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:11
CPC Classifications
F; F24; F24H; F24H1/00; F24H1/22; F24H1/24; F24H1/26; F24H1/28; F24H1/285; F22; F22B; F22B9/00; F22B9/02; F22B9/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
174 words
A return flow boiler having a flue tube connected centrally to one sidewall of a return chamber and being surrounded by a number of fire tubes running backwards therefrom and parallel to the flue tube, a fuel burner being fitted at the end of the flue tube remote from the return chamber and being arranged to direct flame axially into said fire tube, in which the main part of the flue tube is cylindrical and presents a smooth, water-cooled, wall towards the flame, and the outlet of the flue tube is cylindrical over a short distance and noticeably smaller than the cross section of the main part of the flue tube, the transient part between said cylindrical portions being shaped as a truncated cone having its apex just outside the outlet from the flue tube and likewise presenting a smooth, water-cooled wall towards the flame, whereby the marginal portions of the flame within the flue tube will be forced into the core of the flame, when the latter passes out into the return chamber.
Claim 2
Dependent Claim
174 words
A return flow boiler having a flue tube connected centrally to one sidewall of a return chamber and being surrounded by a number of fire tubes running backwards therefrom and parallel to the flue tube, a fuel burner being fitted at the end of the flue tube remote from the return chamber and being arranged to direct flame axially into said fire tube, in which the main part of the flue tube is cylindrical and presents a smooth, water-cooled, wall towards the flame, and the outlet of the flue tube is cylindrical over a short distance and noticeably smaller than the cross section of the main part of the flue tube, the transient part between said cylindrical portions being shaped as a truncated cone having its apex just outside the outlet from the flue tube and likewise presenting a smooth, water-cooled wall towards the flame, whereby the marginal portions of the flame within the flue tube will be forced into the core of the flame, when the latter passes out into the return chamber.
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) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |