FR2783817A1 - Process and installation supplying oxygen and ozone to at least one user of each gas - Google Patents

Abstract

At least one source of oxygen (1, 3) feeds at least one ozone supply line (5) including an ozonator (9) and at least one oxygen supply line (7) and at least one residual gas return line (12) transfers oxygen rich gas from the ozone user post (6) to be combined with the oxygen supply at the oxygen user post (8) The return line includes a purifier (13, 14) to remove impurities from the oxygen and opens into the oxygen supply line. The oxygen source is an air separator using pressure swing adsorption. Process using the above installation with the following stages: a flow of oxygen at a first purity is produced; a first fraction of this flow is sent to an ozone supply line which includes an ozonator; a residual gas rich in oxygen is recovered at a second purity lower than the first; the residual gas flow is combined with the second fraction of the oxygen supply to feed at oxygen user post at a third, intermediate purity. The residual gas is at least partly purified. Use of such an installation in paper production.

Description

PROCESS AND PLANT FOR PROVIDING OXYGEN AND

  OF OZONE, AND USE FOR THE PRODUCTION OF PULP.

  The present invention relates to the supply, from at least one source of oxygen, of oxygen and of ozone to at least one user station.

  ozone and at least one oxygen user station.

  Although using a source of oxygen, frequently an air separation device by pressure variation adsorption, ozone supply installations are generally dedicated to this single supply of ozone, and the energy optimizations proposed aim generally to recycle residual oxygen linked to the use of ozone in the ozonization loop, as described for example in documents EP-A 558 201 (BOC) or

EP-A-406 218 (VOEST-ALPINE).

  The object of the present invention is to propose an installation and a combined process for the joint supply of ozone and oxygen to stations.

  different users, using a simple, flexible and energy-efficient process

than optimized.

  To do this, according to a characteristic of the invention, the installation for supplying oxygen and ozone to at least one ozone user station and to at least one oxygen user station comprises at least a source

  of oxygen supplying at least one ozone supply line, including an ozone

  neur, at least one oxygen supply line, and at least one return line

  waste gas rich in oxygen from the ozone user station, to combine

  sound, at the oxygen user station, with the oxygen supplied by the supply line

oxygen.

  According to another characteristic of the invention, the method of furnishing

  supplying ozone to at least one ozone and oxygen user station to at least one oxygen user station, comprises the following steps: producing a flow of oxygen at a first purity; - send a first part of this oxygen flow at a first purity to an ozone supply line, including an ozonator;

  - extract, from the ozone user station, a stream of residual gas

  che oxygen at a second purity lower than the first purity; and, combining this waste gas flow with a second part of the oxygen flow at a first purity for the supply, at least at the user station, of oxygen at a third purity intermediate between the first and second purities. The invention also relates to the use of such an installation for

the production of paper pulp.

  Other characteristics and advantages of the present invention will emerge

  of the following description of an embodiment, given by way of illustration but

  in no way limiting, made in relation to the appended drawing, in which: FIG. 1 schematically represents an example of installation for the

  implementation of a method according to the invention.

  In the embodiment of Figure 1, we recognize a position of pro-

  oxygen production comprising at least one air separation unit by ad-

  pressure variation sorption 1, of the so-called PSA type, supplied with air by a

  presser 2, and a reservoir 3 of liquid or gaseous oxygen, in reserve or for

  complement production peaks.

  This production unit supplies, via a section of circuit 4, at least one line 5 for supplying ozone to at least one ozone user station 6, and at least one line 7 for supplying oxygen to at least a user station

  of oxygen 8, on the same site as station 6, such as in the usi-

  pulp production facilities or effluent treatment facilities,

  or at a neighboring site. Typically, line 5 incorporates at least one ozo-

  neur 9, for example of the silent electric discharge type, supplied with oxy-

  gene overpressurized by a compressor 10 placed in the upstream part of the

line 5.

  Typically, the ozonator 9 requires oxygen of good purity, greater than

  90% less, which makes a PSA 1 production unit ideal.

  Typically also, in practice, the oxygen user stations 8 are

  contain oxygen with an average purity, between 80% and 92%.

  In this spirit, according to one aspect of the invention, a waste gas rich in oxygen and containing small proportions of ozone and, conventionally, of carbon dioxide, is taken from station 6 by a conduit 11 to be addressed, via a return line 12, to the oxygen supply line 7, in the example shown ,. This return line 12 comprises a device 13 for destroying the residual ozone, for example of the adsorption type, advantageously preceded by a device 14 for cleaning C02, for example also of the adsorption type. To ensure a constant flow through the devices 14 and 13, the gas flow in the return line 12 is assisted by a blower 15 associated with a

  vent valve 16. The return line 12 is connected to the supply line

  supply of oxygen 7 to a mixing and drying device 17, for example

  demister type or passing through a fine metal screen.

  Advantageously, as shown in the figure, the conduit 4 comprises

  carries a regulating expansion valve 18 regulating the pressure of oxygen delivered in lines 5 and 7. As a variant, in the case where the oxygen compressor 10 is of the two-stage Roots type, the first stage can be used to compress all the oxygen flow in line 4 and only assign to line 5 the second stage of the compressor. Advantageously also, the return line 12 comprises, downstream, a regulating valve 19 for controlling the flow rate of the purified return gas

  introduced into line 7, the pressure being regulated by the vent valve 16.

  With the diagram thus described, a representative example of the process can

  be as follows: the PSA unit 1 supplies a flow rate Q of oxygen at a purity of 93%.

  This flow Q is divided into a flow Q / 2 in line 5 and Q / 2 in line 7. Downstream of line 12 a reduced flow of oxygen, at a purity of the order of 85% without purification of 90% CO2 with CO2 purification, is mixed with the oxygen flow at

  93% upstream of line 7 to provide, downstream of line 7, a

  bit, much higher than Q / 2 oxygen at a purity of about 88-89% or 91-

  92%, respectively, below the purity of the oxygen supplied by source 1 and

  higher than the purity of recycled oxygen available downstream of the cooling line

round 12.

  Alternatively, instead of mixing the oxygen of different purities in the oxygen supply line 7, the mixing can be carried out, downstream, at the

  user station level 8 o the return flow routed via line 12 is mixed

  swapped with all or part of the good purity flow routed by direct line 7-

up to user station 8.

Claims (8)

  1. Installation for supplying oxygen and ozone to at least one station   ozone user (6) and at least one oxygen user station (8),   nant: at least one oxygen source (1; 3) supplying at least one line of   supply of ozone (5) including an ozonator (9), and at least one line (7) of furnace   oxygen supply, and at least one return line (12) of oxygen-rich waste gas from the ozone user station (6) for combination, to the oxygen user station (8),   with the oxygen supplied by the oxygen supply line (7).   2. Installation according to claim 1, characterized in that the return line (12) comprises at least one station (13; 14) for purifying oxygen impurities. 3. Installation according to claim 1 or claim 2, characterized in that the line (12) of residual gas return opens into the line (7) of supply of oxygen.   4. Installation according to one of claims 1 to 3, characterized in that   that the oxygen source includes a device for the separation of air by adsor- pressure variation (1).   5. A method of supplying ozone to at least one ozone user station (6) and oxygen to at least one oxygen user station (8), comprising the following steps: producing an oxygen flow (4 ) to a first purity; directing a first part of this oxygen flow to an ozone supply line (5), including an ozonator (9); extracting, from the ozone user station (6), a stream of oxygen-rich waste gas at a second purity lower than the first purity; and, combine this waste gas flow with a second part of the oxygen flow at a first purity for the supply, at least to the oxygen user station (8), of oxygen at a third purity intermediate between the first and second purities.   6. Method according to claim 5, characterized in that the gas flow   waste is at least partially purified of oxygen impurities.   7. Method according to claim 5 or claim 6, characterized in that the oxygen flow at a first purity is obtained by separation of the air   by pressure variation adsorption.   8. Use of an installation according to one of claims 1 to 4 for the production of pulp.