METHOD OF OPERATING A VPSA ADSORPTION DEVICE

Abstract

This method of operating a pressure variation adsorption device (1) having one or more adsorbers (2, 4) intended to adsorb a first component of a fluid to isolate at the outlet a second component of this fluid and a reservoir (6) placed downstream of the adsorber(s) (2, 4) to store the fluid treated by the adsorber(s) (2, 4), comprises a start-up sequence including a step of transferring at least a portion of the fluid stored in the reservoir (6) into the adsorber(s) (2, 4).

Description

nitrogen, initially trapped in the second adsorber 4. This step preferably comprises limiting the regeneration flow rate to a predetermined threshold value, for example of the order of 10% of the flow rate of oxygen delivered, in particular by means of the flow limiter 16a. The saturation stage of the first adsorber 2 ends when the pressure in the first adsorber 2, and more precisely in the inlet pipe 2a, has reached a pressure equal to the pressure in the tank 6. In a second step (figure 6), the production cycle includes a step of delivering the second gas, here dioxygen, by the first adsorber 2. This step begins with the opening of the valve 12a which allows the outlet 2b of the first adsorber 2 to be put into communication with the tank 6, so as to supply the tank 6 with dioxygen via the collection circuit 12. The device 1 advantageously comprises a timer management system intended to control the closing of the valves 18a, 12a and 22b and the opening of the valves 18b, 22a and 14a after a predetermined period of time, for example of the order of 60 to 100s, from the start of the saturation step. Thus, once this period of time has elapsed, the step of delivering the second gas by the first adsorber 2 ceases, and the production cycle comprises a third step (figure 7), called balancing, during which the pressures between the first adsorber 2 and the second adsorber 4 are balanced, via the balancing circuit 14. A portion of the gas flow passing from the second adsorber 4 to the first adsorber 2 also passes, if necessary, through the regeneration flow circuit 16, which makes it possible to shorten the duration of this balancing step. This balancing step stops after a predetermined duration, of the order of 0 to 10s, where the timer management system controls the closing of the balancing valve 14a. The production cycle then includes the repetition of the previous steps applied to the second adsorber 4. The production of the second gas, or oxygen, is therefore cyclical and is carried out alternately using the first and second adsorbers 2, 4. Thus, the production cycle comprises a fourth step (figure 8), during which the saturation of the second adsorber 4 takes place, taking place in a similar manner to the saturation of the first adsorber 2, where only the valves 18b, 22a are open. Simultaneously, the purging and regeneration of the first adsorber 2 takes place, as well as the circulation of a regeneration flow, via the regeneration flow circuit 16, from the second adsorber 4 to the first adsorber 2. The production cycle continues with a fifth stage, corresponding to the delivery of second gas (dioxygen) by the second adsorber 4, which begins as soon as the pressure in the second adsorber has reached a pressure equal to the pressure in the tank 6, and by opening the valve 12b. The timer management system then controls the closing of the valves 18b, 12b and 22a and the opening of the valves 18a, 22b and 14a after the predetermined period of time from the start of the saturation step of the second adsorber4. The step of delivering the second gas by the second adsorber4 ceases, and the step of balancing the pressures between the adsorbers 2, 4 begins. The balancing step ceases after the predetermined period of time, when the timer management system controls the closing of the balancing valve 14a. The operating method may of course comprise several consecutive production cycles, each of which may be a reiteration of the steps illustrated in Figures 5 to 9. Preferably, after each start-up sequence, the operating method comprises at least one production cycle, in order to have a sufficient quantity of the second gas in the tank to accelerate the start-up sequence the next time the device 1 is started. Since, during the start-up sequence, a transfer of the gas contained in the tank 6 takes place into the adsorbers 2, 4, and since this transfer may tend to modify the balance of the booster 20 and the vacuum pump 24, it may advantageously be provided, to ensure a good rate of second gas (dioxygen) from the start of production, to reduce from one cycle to the next the predetermined time interval of the saturation / delivery steps progressively, that is to say the duration including the saturation step and the delivery step, and this during the first production cycles, for example over the first six cycles, after which the predetermined time interval returns to the standard value of the order of 60 to 100s. It will be noted that the stopping of the device 1 preferably always takes place after the end of the delivery step of the first adsorber 2, and that the single step of pressurizing each adsorber 2, 4 during the start-up sequence always begins with the pressurization of this first adsorber 2. Furthermore, during a production cycle, when the oxygen level measured in the tank 6 falls below a predetermined threshold value, for example of the order of 90% by volume, the valve 8 is closed and the valve 10 opens (figure 9). Thus, the tank 6 is connected to the suction of the booster 20 in order to recover the oxygen-enriched gas which is contained in the tank 6. Thanks to this recovery, the phase of restoring an oxygen level equal to or greater than the predetermined threshold value is accelerated, because it is then a gas mixture containing a dioxygen level greater than the content of the ambient air (21%) which is injected into the adsorbers 2, 4. During this restoration, the production cycle by the adsorbers 2, 4 continues to take place normally, the valve 12a being shown here open in figure 9. The present invention also relates to a device 1 having all or part of the aforementioned characteristics, suitable for implementing the operating method described above, in which the device 1 comprises the second outlet conduit 6c connecting the reservoir 6 and the supply circuit 18, and opening or closing means, such as the valve 10, to allow or prevent the recovery of the second gas, or dioxygen, contained in the reservoir 6 into the supply circuit 18. Of course, the invention is in no way limited to the embodiment described above, this embodiment having been given only as an example. Modifications are possible, in particular from the point of view of the constitution of the various elements or by the substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

CLAIMS 1. Method for operating a pressure swing adsorption device (1) of the VPSA type, the device (1) having one or more adsorbers (2, 4) intended to adsorb a first component of a gas mixture to isolate at the outlet a second component of this gas mixture, and a tank (6) placed downstream of the adsorber(s) (2, 4) to store the gas mixture treated by the adsorber(s) (2, 4), characterized in that the operating method comprises a start-up sequence taking place after starting up the device (1) and before one or more production cycles during which the gas mixture treated by the adsorber(s) (2, 4) is sent into the tank (6), said start-up sequence including a step of transferring at least a portion of a gas mixture produced during a previous use of the device (1) and stored in the tank (6) into the adsorber(s) (2, 4),and in which the production cycle(s) comprise, in the event of the level of second component in the gas mixture contained in the tank becoming lower than a predetermined threshold value, a step of injecting this gas mixture contained in the tank (6) into the adsorber(s) (2, 4).

2. Method according to claim 1, in which the start-up sequence comprises, before the transfer step, an initial step of reducing the pressure in the adsorber(s) (2, 4) to a pressure lower than a pressure in the tank (6).

3. Method according to claim 2, in which the initial step of reducing the pressure in the adsorber(s) (2, 4) is a vacuum drawing step.

4. Method according to one of claims 1 to 3, in which, after the transfer step, the or each adsorber (2, 4) undergoes a single pressurization step.

5. Method according to claim 4, in which, after the single pressurization step, each adsorber (2, 4) undergoes a single vacuum drawing step.

6. Method according to one of claims 1 to 5, in which the device (1) comprises two adsorbers (2, 4), and the production cycle comprises a step of balancing the pressures between the two adsorbers (2, 4) by natural convection.

7. Method according to one of claims 1 to 6, in which, after the start-up sequence, the method comprises several production cycles each including a saturation step of the or each adsorber (2, 4) followed by a delivery step, and the duration of the pair of saturation / delivery steps decreases at each cycle from the first production cycle, for a predetermined number of production cycles.

8. VPSA type pressure variation adsorption device (1) suitable for implementing the operating method according to one of claims 1 to 7, the device (1) comprising one or more adsorbers (2, 4) intended to adsorb a first component of a gas mixture to isolate at the outlet a second component of this gas mixture, a reservoir (6) placed downstream of the adsorber(s) (2, 4) to store the gas mixture treated by the adsorber(s) (2, 4), and a supply circuit (18) comprising compression means configured to send the gas mixture to be treated into the adsorber(s) (2, 4) so ​​as to increase the pressure in the adsorber(s) (2, 4) up to a predetermined pressure, characterized in that the reservoir (6) comprises an outlet conduit (6c) connecting the reservoir (6) to the supply circuit (18),and flow opening or closing means configured to allow or prevent the circulation of the gas mixture contained in the tank (6) through the outlet conduit (6c) to the supply circuit (18).,

Images