Drying and gas or vapor contact with solids – Apparatus – For diverse operations on treated material
Reexamination Certificate
1999-05-28
2001-04-17
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
For diverse operations on treated material
C034S084000, C266S249000, C266S250000
Reexamination Certificate
active
06216358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas-quenching cell, and more specifically, to the gas stirring system for such a cell.
2. Discussion of the Related Art
Gas-quenching methods have many advantages as compared to liquid-quenching methods, especially the fact that the processed elements remain dry and clean.
The paper entitled “La vitesse de refroidissement, point capital pour le traitement en fours sous vide” by J. Naudot, published in “Traitement thermique” N°133-79, France, discusses the influence of several parameters and of the gas choice on the efficiency of the quenching, mainly on the quenching speed. It is constant that if the quenching speed is to be increased, the gas mass flow, that is, its speed and its static pressure should be increased. The above-mentioned paper mentions that beyond 4 to 5 bars of static nitrogen pressure, the efficiency gain is to be tempered by the cost of the high power engines necessary for the stirring and the high gas consumption.
European patent 0,313,888 discloses using light gases, such as helium or hydrogen, at high static pressures. The power of the stirring engines would then be comparable to that reached for heavier gases at lower pressures. However, light gases are particularly expensive (helium) or dangerous (hydrogen).
The quenching efficiency, such as defined in the above documents, is relative to the quenching speed.
Gas-quenching installations are presently used only for quenching operations, since they are generally optimized to obtain as high a gas mass flow as possible.
Summary of the invention
An object of the present invention is to provide a gas-quenching cell offering a widened range of possibilities.
Another object of the present invention is to provide such a quenching cell offering optimum performance over a wide range of gas mass flows.
To achieve these objects, the present invention provides a cell for gas-quenching a load, including guiding plates and a stirring element driven by an engine to cause a gas flow between the load and an exchanger. The stirring element is an adjustable pitch blade propeller.
According to an embodiment of the present invention, the pitch of the blade propeller is adjusted so that, at a desired gas mass flow, the engine operates with a maximum efficiency of power transmission to the flow.
According to an embodiment of the present invention, the cell is cylindrical or parallelepiped-shaped and the exchanger is arranged axially on either side of the load, the axis of the blade propeller being perpendicular to the plane of the exchanger.
According to an embodiment of the present invention, the cell is separate from a furnace used to heat up the load before cooling.
According to an embodiment of the present invention, the cell includes a duct forming a loop external to the cell, through which is forced the gas flow.
According to an embodiment of the present invention, the exchanger is arranged in the duct.
According to an embodiment of the present invention, the blade propeller is arranged in the duct.
According to an embodiment of the present invention, the exchanger is in the form of a disk arranged so that it is run through by opposite gas flows at its periphery and at its center.
According to an embodiment of the present invention, the exchanger is arranged as a crown around the blade propeller axis.
According to an embodiment of the present invention, the gas is nitrogen or a mixture including at least 50% of nitrogen, at a pressure between 1 and 50 bars.
According to an embodiment of the present invention, the cell includes several stirring blade propellers.
The foregoing objects, features and advantages of the present invention will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings.
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La Vitesse de Refroidissement, Point Capital Pour Le Traitement Thermique en Fours Sous Vide, by J. Naudot, p. 31-35, vol. 133, No. 3, 1979, XP002093519.
Buchanan & Ingersoll PC
Etudes Et Constructions Mecaniques
Plevy Arthur L.
Wilson Pamela
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