Gas separation: processes – Solid sorption – Including reduction of pressure
Reexamination Certificate
2000-10-24
2001-11-20
Simmons, David A. (Department: 1724)
Gas separation: processes
Solid sorption
Including reduction of pressure
C095S118000, C095S122000, C095S139000, C096S132000, C423S230000
Reexamination Certificate
active
06319303
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for purifying a gas by adsorption of a first impurity and of a second impurity, of the type in which several adsorbers are used cyclically and selectively in the adsorption phase and in the regeneration phase.
The invention is applicable, for example, to the purification of air for the purpose of distilling it.
BACKGROUND OF THE INVENTION
For such an application, it is known to use a purification system comprising two identical adsorbers, the operation of which alternates, i.e. one is in the adsorption phase while the other is in the regeneration phase.
When the air flow to be treated is large, it is also known to use four identical adsorbers coupled in pairs. The two adsorbers of one and the same pair operate in parallel. The operation of the two pairs of adsorbers alternates, so that one pair of adsorbers is in the adsorption phase while the other is in the regeneration phase. Such a parallel operation makes it possible to treat large flows while limiting the manufacturing constraints on the adsorbers.
SUMMARY OF THE INVENTION
An object of the invention is to provide a process of the aforementioned type which makes it possible, especially, to reduce even more the costs of manufacturing or of operating an air distillation plant in which the process is implemented.
To this end, the subject of the invention is a process of aforementioned type, characterized in that at least two main adsorbers and at least one auxiliary adsorber are used, in that, during at least a first step, the gas is purified by adsorbing the two impurities by passing through at least a first of the main adsorbers without passing through a first auxiliary adsorber, and in that simultaneously the second main adsorber and the or each auxiliary adsorber are regenerated in parallel, then, during a second step, at least some of the gas flow is purified by adsorption of the two impurities by passing in series through the first main adsorber and through the first auxiliary adsorber.
According to particular embodiments, the process may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:
during the second step, the pressure of the gas between the first main adsorber and the first auxiliary adsorber is changed;
during the second step, the gas between the first main adsorber and the first auxiliary adsorber is compressed;
only one auxiliary adsorber is used;
between the first step and the second step, the gas is purified by adsorbing the two impurities by passing through a second main adsorber;
at least two auxiliary adsorbers are used;
the first step is interrupted when the first main adsorber is substantially saturated with the second impurity;
each auxiliary adsorber comprises an adsorption packing comprising a single adsorbent material;
the first impurity is H
2
O and the second impurity CO
2
;
the gas is air.
The subject of the invention is also a system for purifying a gas in order to implement a process as defined hereinabove, characterized in that it comprises a line for supplying the gas to be purified, a line for discharging the purified gas, a line for supplying a regeneration gas, a line for discharging the regeneration gas, at least two main adsorbers and at least one auxiliary adsorber, the main adsorbers comprising a packing for adsorbing the first and second impurities, and each auxiliary adsorber comprising a packing for absorbing at least the second impurity, and in that the system furthermore comprises first connection means, in order to connect the main adsorbers to the line for discharging the purified gas without passing through the auxiliary adsorber or without passing through any of the auxiliary adsorbers, second connection means, in order to connect each main adsorber in series with an auxiliary adsorber, and third connection means, in order to connect the or each auxiliary adsorber and at least one main adsorber in parallel with the line for supplying the regeneration gas.
According to particular embodiments, the system may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:
the said second connection means include means for changing the gas pressure;
the said second connection means include compression means;
the purification system comprises a single auxiliary adsorber;
the purification system comprises at least two auxiliary adsorbers;
each auxiliary adsorber comprises an adsorption packing comprising a single adsorbent material;
the first impurity is H
2
O and the second impurity CO
2
; and
the gas is air.
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Guillard Alain
Le Bot Patrick
L'Air Liquide, Societe Anonyme pour l'Etude et l'
Lawrence Frank M.
Simmons David A.
Young & Thompson
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