Patent US3708536A successfully refreshed from Google Patents.
US3708536A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recycling melamine synthesis offgas to urea synthesis
Assignee: BASF SE
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Filing: 1969-07-23
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Granted: 1973-01-02
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Expires: 1989-07-23
Abstract
Abstract OFFGAS CONSISTING ESSENTIALLY OF AMMONIA AND CARBON DIOXIDE IS FORMED IN THE SYNTHEIS OF MELAMINE FROM UREA. THIS IS ABSORBED IN TWO STAGES IN WATER OR AN AQUEOUS SOLUTION OF AMMONIUM CARBAMATE OR UREA FOR RETURN TO UREA SYNTHESIS. IN THE FIRST STAGE THE GAS IS TREATED WITH AN AMOUNT OF ABSORBENT SOLUTION WHICH IS NOT SUFFICIENT TO ABSORB THE WHOLE OF THE GAS. THE REMAINING OFFGAS AND THE SOLUTION FORMED ARE THEN COMPRESSED SEPARATELY FROM ONE ANOTHER TO THE PRESSURE WHICH IS SUFFICIENT FOR THE ABSORPITON OF THE REMAINING OFFGAS INTO THE SOLUTION AND THE OFFGAS IS THEN ABSORBED. THE SOLUTION THUS FORMED IS RETURNED TO THE HIGH PRESSURE SECTION OF THE SYNTHESIS PLANT.
Inventors
- 👤 E Hillenbrand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:22
CPC Classifications
C; C07; C07C; C07C273/00; C07C273/02; C07C273/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |