Method of operation of a cupola
AssigneeGeneral Motors Corporation
InventorIsidore Hodes
Life of this patent
Estimating the term…
Abstract
Conventional cupola apparatus and its operation are modified by suppressing the entrance of external air to the cupola and replacing the nitrogen component of the air injected into the conventional cupola with a recycled fraction of the cupola gas consisting substantially of CO and CO.sub.2 withdrawn from the cupola at a point above the melting zone and replacing the oxygen component of the air with externally supplied substantially pure oxygen. The remaining fraction of the cupola gas is exhausted from the cupola system. When the cupola is thusly operated on a steady state basis, a balance is maintained so that the atomic amount of the oxygen exhausted from the system is equal to the atomic amount of the injected oxygen.
Claims5
A method of operating a cupola system having alternate layers of coke and metal to be melted arranged in a stack and having a combustion zone near the bottom of the stack and progressively upward along the stack a reducing zone, a melting zone and a preheat zone, comprising
- continuously introducing substantially pure oxygen into said combustion zone and continuously recycling a fraction of the cupola gas from said preheat zone to said combustion zone and exhausting from said cupola system the remaining fraction of said cupola gas,
- the rate of oxygen flow into said combustion zone and the fraction of cupola gas exhausted being balanced so that the amount of said pure oxygen introduced into said combustion zone is substantially equal to the amount of the oxygen in said remaining fraction, said pure oxygen being the only gas fed into said cupola system after the system is started in operation.
In a method of operating a cupola system of the type comprising alternate layers of coke and metal to be melted arranged in a stack and having a combustion zone near the bottom of the stack, a reducing zone, a melting zone, a preheat zone and an exhaust conduit for conveying cupola gas from said cupola system comprising
- subjecting the coke in said combustion zone to an air blast to produce CO.sub.2 gas which is subsequently at least partially reduced to CO in accordance with CO.sub.2 + C = 2CO in said reducing zone to constitute said cupola gas and then passed upward in said stack through said melting zone and into said preheat zone,
- then progressively returning an increasing fraction of said cupola gas from said preheat zone to said combustion zone and simultaneously progressively reducing the amount of said air blast to said combustion zone, simultaneously progressively injecting substantially pure oxygen to said combustion zone and progressively expelling the remaining fraction from said system so as to keep the rate of oxygen injected into said combustion zone and the amount of cupola gas expelled from said system balanced so that the amount of said pure oxygen injected into said combustion zone is substantially equal to the amount of the oxygen removed from the system,
- then continuing to inject only substantially pure oxygen into said combustion zone, to return a fraction of said cupola gas from said preheat zone to said combustion zone and to remove cupola gas from said system in accordance with the said balance.
In a method of operating a cupola system of the type comprising alternate layers of coke and metal to be melted arranged in a stack and having a combustion zone near the bottom of the stack, a reducing zone, a melting zone, a preheat zone and an exhaust conduit for conveying cupola gas from said cupola system comprising,
- subjecting the coke in said combustion zone to an air blast to produce CO.sub.2 gas which is subsequently at least partially reduced to CO in accordance with CO.sub.2 + C = 2CO in said reducing zone to constitute said cupola gas and then passing said cupola gas upwardly in said stack through said melting zone and into said preheat zone,
- then progressively returning an increasing fraction of said cupola gas from said preheat zone to said combustion zone and simultaneously progressively reducing the amount of said air blast to said combustion zone, simultaneously progressively injecting substantially pure oxygen to said combustion zone and progressively expelling the remaining fraction from said system so as to keep the rate of oxygen injected into said combustion zone and the amount of cupola gas expelled from said system balanced so that the amount of said pure oxygen injected into said combustion zone is substantially equal to the amount of the oxygen removed from the system,
- then continuing to inject only substantially pure oxygen into said combustion zone, to return a fraction of said cupola gas from said preheat zone to said combustion zone and to remove cupola gas from said system in accordance with said balance to thereby maintain a steady melting rate,
- then selectively varying the rate of oxygen or of recycled gas, or of both, injected into said combustion zone to vary the melting rate and removing cupola gas from said system in accordance with said balance.
In a method of operating a cupola system of the type comprising alternate layers of coke and metal to be melted arranged in a stack and having a combustion zone near the bottom of the stack, a reducing zone, a melting zone, a preheat zone and an exhaust conduit for conveying cupola gas from said cupola system comprising,
- subjecting the coke in said combustion zone to an air blast to produce CO.sub.2 gas which is subsequently at least partially reduced to CO in accordance with CO.sub.2 + C = 2CO in said reducing zone to constitute said cupola gas and then passing said cupola gas upwardly in said stack through said melting zone and into said preheat zone,
- then progressively returning a fraction of the cupola gas from said preheat zone to said combustion zone and simultaneously progressively reducing the amount of said air blast to said combustion zone, simultaneously progressively injecting sustantially pure oxygen to said combustion zone and progressively expelling the remaining fraction from said system so as to keep the rate of oxygen expelled into said combustion zone and the amount of capula gas removed from said system balanced so that the amount of said pure oxygen injected into said combustion zone is substantially equal to the amount of the oxygen removed from the system, p1 then continuing to inject only substantially pure oxygen into said combustion zone, to return a fraction of said cupola gas from said preheat zone to said combustion zone and to remove cupola gas from said system in accordance with said balance to thereby maintain a steady melting rate,
- then continuing to charge only coke to said stack to suppress influx of air into said stack until all the metal has melted and then stopping the injection of the oxygen and then recycling said cupola gas to shut down said cupola.
In a method of operating a cupola system of the type comprising alternate layers of coke and metal to be melted arranged in a stack and having a combustion zone near the bottom of the stack, a reducing zone, a melting zone, a preheat zone and an exhaust conduit for conveying cupola gas from said cupola system comprising
- subjecting the coke in said combustion zone to an air blast at an initial flow rate to produce CO.sub.2 gas which is subsequently at least partially reduced to CO in accordance with CO.sub.2 + C = 2CO in said reducing zone to constitute said cupola gas and then passed upward in said stack through said melting zone and into said preheat zone,
- then progressively reducing the amount of said air blast to said combustion zone from said initial flow rate until the air is completely shut off while sumultaneously synchronously and progressively injecting increasing amounts of substantially pure oxygen to said combustion zone until the rate of injection of said oxygen is substantially equivalent to the rate of flow of oxygen at the initial flow rate of said air blast and recycling cupola gas from said preheat zone to said combustion zone until the rate of recycled cupola gas is substantially equivalent to the rate of flow of nitrogen at the initial flow rate of said air blast, and thereafter
- continuing to inject substantially pure oxygen into said combustion zone and to recycle said cupola gas into said combustion zone at their respective said rates while exhausting cupola gas from said cupola system at a rate such that the amount of oxygen in said exhaust is substantially equivalent to the amount of pure oxygen injected, said oxygen being the only gas fed into said cupola system after said air is shut off.
Dependencies are inferred from the claim text.