US3898124A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic control of a continuous digester, including level, concentration, and flow meters
Assignee: ABB Norden Holding AB
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Filing: 1974-05-07
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Granted: 1975-08-05
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Expires: 1994-05-07
Abstract
Abstract In a continuous digester which has a boiler with a rotatable bottom scraper and a chip and lye inflow at the top as well as a wash inflow into and a pulp outflow from the boiler, the concentration at the pulp outflow is measured and is used to control the rotation of the scraper so as to maintain a constant concentration of the outgoing pulp. A flow meter at the pulp outflow controls a throttle valve to regulate the outflow. The liquid in the top of the digester is measured and is used to control the devices which feed chips to the digester. Measurement of the pressure in the digester is used to control the flow of black liquor at the chip and lye inflow. The chips are fed in by a chip screw which in turn is fed by a segmental wheel, and the speeds of the chip screw and segmental wheel are maintained proportional to each other.
Inventors
- 👤 Torbjorn Olson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:44
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/228
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
170 words
A CONTINUOUS DIGESTER COMPRISING A BOILER WITH A ROTATABLE BOTTOM SCRAPER WITH A DRIVE MOTOR CHIPS AND LYE INFLOW AT THE TOP OF THE BOILER WASH LIQUOR INFLOW MEANS TO THE BOTTOM OF THE BOILER AND THE PULP OUTFLOW MEANS FROM THE BOTTOM OF THE BOILER SAID DIEGESTER COMPRISING: A. A LEVEL METER FOR MEASURING THE LIQUID LEVEL IN THE TOP OF THE DIGESTER CHIP FEEDING MEANS CONNECTED TO THE CHIP INFLOW MEANS AND MEANS RESPONSIVE TO THE OUTPUT SIGNAL OF SAID LEVEL METER TO CONTROL THE CHIP FEEDING MEANS, B. A CONCENTRATION METER IN THE PULP OUTFLOW MEANS MEANS FOR CONTROLLING THE DRIVE MOTOR SAID MOTOR CONTROLLING MEANS INCLUDING MEANS RESPONSIVE TO A SIGNAL FROM THE CONCENTRATION METER TO REGULATE THE SPEED OF THE SCRAPER TO MAINTAIN A PREDETERMINED CONCENTRATION OF THE OUTGOING PULP AND C. A FLOW METER AND A THROTTLE VALVE IN THE PULP OUTFLOW MEANS AND MEANS RESPONSIVE TO THE FLOW METER FOR CONTROLLING THE THROTTLE VALVE TO OBTAIN A PREDETERMINED OUTFLOW FOR THE OUTGOING PULP.
Claim 2
Dependent Claim
170 words
A CONTINUOUS DIGESTER COMPRISING A BOILER WITH A ROTATABLE BOTTOM SCRAPER WITH A DRIVE MOTOR CHIPS AND LYE INFLOW AT THE TOP OF THE BOILER WASH LIQUOR INFLOW MEANS TO THE BOTTOM OF THE BOILER AND THE PULP OUTFLOW MEANS FROM THE BOTTOM OF THE BOILER SAID DIEGESTER COMPRISING: A. A LEVEL METER FOR MEASURING THE LIQUID LEVEL IN THE TOP OF THE DIGESTER CHIP FEEDING MEANS CONNECTED TO THE CHIP INFLOW MEANS AND MEANS RESPONSIVE TO THE OUTPUT SIGNAL OF SAID LEVEL METER TO CONTROL THE CHIP FEEDING MEANS, B. A CONCENTRATION METER IN THE PULP OUTFLOW MEANS MEANS FOR CONTROLLING THE DRIVE MOTOR SAID MOTOR CONTROLLING MEANS INCLUDING MEANS RESPONSIVE TO A SIGNAL FROM THE CONCENTRATION METER TO REGULATE THE SPEED OF THE SCRAPER TO MAINTAIN A PREDETERMINED CONCENTRATION OF THE OUTGOING PULP AND C. A FLOW METER AND A THROTTLE VALVE IN THE PULP OUTFLOW MEANS AND MEANS RESPONSIVE TO THE FLOW METER FOR CONTROLLING THE THROTTLE VALVE TO OBTAIN A PREDETERMINED OUTFLOW FOR THE OUTGOING PULP.
Claim 3
Dependent Claim
21 words
A continuous digester according to claim 1, having the concentration and flow meters arranged in series in the pulp outflow means.
Claim 4
Dependent Claim
46 words
A continuous digester according to claim 1, having a pressure measuring device associated with the digester for measuring its pressure, and means responsive to the output signal of said pressure measuring device for controlling the flow of black liquor at the chip and lye inflow means.
Claim 5
Dependent Claim
27 words
A continuous digester according to claim 1, in which said means for controlling the throttle valve includes means to maintain a constant outflow for the outgoing pulp.
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) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |