Process for treating a sulfide-containing waste lye

Abstract

The invention relates to a process for treating a sulfide-containing waste lye from a lye scrub in which the waste lye and oxygen or an oxygen-containing gas mixture is fed to an oxidation reactor (10) and in the latter is subjected to a wet oxidation, steam being fed into the oxidation reactor (10). It is provided that an oxidation reactor (10) with a number of chambers (11-19), of which a first chamber (11) has a greater volume than a second chamber (12), is used, the waste lye and the oxygen or the oxygen-containing gas mixture being fed to the first chamber (11), fluid flowing out of the first chamber (11) being transferred into the second chamber (12), the steam quantity and/or steam temperature of the steam fed into the oxidation reactor (10) being controlled by a control device (TIC), and the steam fed into the oxidation reactor (10) being at least partially fed into the first chamber (11) and into the second chamber (12). A corresponding installation (100) and also a corresponding oxidation reactor (10) are likewise the subject of the invention.

Claims

1. A process for treating a sulfide-containing waste lye from a lye scrub in which the waste lye and oxygen or an oxygen-containing gas mixture is fed to an oxidation reactor (10) and in the latter is subjected to a wet oxidation, steam being fed into the oxidation reactor (10), characterized in that an oxidation reactor (10) with a number of chambers (11-19), of which a first chamber (11) has a greater volume than a second chamber (12), is used, the waste lye and the oxygen or the oxygen-containing gas mixture being fed to the first chamber (11), fluid flowing out of the first chamber (11) being transferred into the second chamber (12), the steam quantity and/or steam temperature of the steam fed into the oxidation reactor (10) being controlled by a control device (TIC), and the steam fed into the oxidation reactor (10) being at least partially fed into the first chamber (11) and into the second chamber (12).

2. The process according to claim 1, in which steam is fed into the oxidation reactor (10) as saturated steam or steam superheated by at most 5 to 10 C., the steam temperature of the steam fed into the oxidation reactor (10) being set by mixing in water in superheated steam.

3. The process according to claim 2, in which the quantity of the saturated steam and/or of the superheated steam and/or the water is set by means of the control device (TIC).

4. The process according to claim 1, in which the steam quantity and/or steam temperature of the steam fed into the oxidation reactor (10) is controlled on the basis of a temperature detected in the first chamber (11) and/or the second chamber (12) and on the basis of a detected temperature of a fluid flowing out of the reactor (10).

5. The process according to claim 4, in which the control comprises stipulating a temperature setpoint value and a maximum temperature in the first chamber (11) and/or the second chamber (12).

6. The process according to claim 5, in which the temperature setpoint value is stipulated on the basis of the temperature of the fluid flowing out of the reactor (10).

7. The process according to claim 1, in which volume of first chamber (11) is greater than an average volume of all the chambers (11-19) of the oxidation reactor (10) and/or comprises at least one third and at most two thirds of an overall volume of all the chambers (11-19).

8. The process according to claim 1, in which steam quantity of the steam fed into the oxidation reactor (10) is controlled in a range of 5 to 100%.

9. The process according to claim 1, in which the steam is at least partially introduced into the oxidation reactor (10) by means of a steam feeding device (21, 22), which has a cylindrical section (211) with a centre axis (212) and a wall (213), the centre axis (212) being aligned perpendicularly, a number of groups of openings (214) being formed in the wall, each of the groups comprising a number of the openings (214), and the number of openings (214) of each of the groups being arranged in one or more planes (215) that is or are in each case aligned perpendicularly to the centre axis (212).

10. The process according to claim 1, in which the waste lye and the oxygen or the oxygen-containing gas mixture are premixed before they are fed to the oxidation reactor (10), and in which the waste lye and the oxygen or the oxygen-containing gas mixture are fed to the oxidation reactor (10) at ambient temperature.

11. The process according to claim 1, in which the oxidation reactor (10) is operated at a pressure level of 20 to 50 bar and at a temperature level of 150 to 220 C.

12. Installation (100) for treating a sulfide-containing waste lye from a lye scrub, with means which are set up for feeding the waste lye and oxygen or an oxygen-containing gas mixture to an oxidation reactor (10) and in the latter subjecting it to a wet oxidation, means which are set up for feeding steam into the oxidation reactor (10) being provided, characterized in that the oxidation reactor (10) has a number of chambers (11-19), of which a first chamber (11) has a greater volume than a second chamber (12), means being provided for feeding the waste lye and the oxygen or the oxygen-containing gas mixture to the first chamber (11), transferring fluid flowing out of the first chamber (11) into the second chamber (12), controlling a steam quantity and/or steam temperature of the steam fed into the oxidation reactor (10) by a control device (TIC), and at least partially feeding the steam fed into the oxidation reactor (10) into the first chamber (11) and into the second chamber (12).

13. Oxidation reactor (10) for use in an installation (100) for treating a sulfide-containing waste lye from a lye scrub, the installation (100) having means which are set up for feeding the waste lye and oxygen or an oxygen-containing gas mixture to the oxidation reactor (10) and in the latter subjecting it to a wet oxidation, the oxygen reactor (10) having means which are set up for feeding steam into the oxidation reactor (10), characterized in that the oxidation reactor (10) has a number of chambers (11-19), of which a first chamber (11) has a greater volume than a second chamber (12), means being provided for feeding the waste lye and the oxygen or the oxygen-containing gas mixture to the first chamber (11), transferring fluid flowing out of the first chamber (11) into the second chamber (12), controlling a steam quantity and/or steam temperature of the steam fed into the oxidation reactor (10) by a control device (TIC), and at least partially feeding the steam fed into the oxidation reactor (10) into the first chamber (11) and into the second chamber (12).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 shows in a simplified representation a process for treating a waste lye according to an embodiment of the invention.

[0057] FIG. 2 illustrates in a schematic partial representation an oxidation reactor for use in an installation according to an embodiment of the invention.

[0058] FIG. 3A illustrates a steam feeding device for use in an installation according to an embodiment of the invention in a first configuration.

[0059] FIG. 3B illustrates a steam feeding device for use in an installation according to an embodiment of the invention in a second configuration.

DETAILED DESCRIPTION OF THE DRAWINGS

[0060] In the figures, elements that functionally or structurally correspond to one another are respectively indicated by identical designations. For the sake of clarity, these elements are not explained repeatedly.

[0061] In FIG. 1, an installation for treating a waste lye according to a particularly preferred embodiment of the invention is schematically illustrated and is denoted overall by 100.

[0062] A central component of the installation 100 illustrated in FIG. 1 is an oxidation reactor 10. In the example represented, this oxidation reactor has altogether nine reactor chambers 11 to 19, at least however four reactor chambers.

[0063] A chamber 11 arranged lowest down in the example represented, near the inlet, and optionally the chamber 12 following thereafter are respectively provided with a steam feeder 21 and 22, for example a steam lance or a steam chamber protruding into the respective chamber 11, 12. The chamber 11 near the inlet is increased in size in comparison with the other chambers 12 to 19, with the aim of achieving relatively high conversions in this chamber, and in this way preventing the occurrence of high reactant concentrations near the inlet. The chamber 11 of increased size is larger than the average chamber volume and typically comprises more than one third of the overall reactor volume and typically less than two thirds thereof. The smaller chambers 12 to 19 above it have the task of reducing the residence time distribution in order to optimize the conversion.

[0064] The steam feeders 21, 22 are part of a steam system 20, which is based on a temperature indicator control TIC, to which a number of temperature indicators TI that are arranged at the chambers 11 and 12 and also at the outlet of the oxidation reactor 10 are connected. The temperature indicator control TIC controls two valves 23, 24, which are arranged upstream of a deheater or desuperheater 25, and by means of which an inflow of superheated steam 1 or boiler feed water 2 to the desuperheater 25 is set. Fluid 3 flowing out of the desuperheater 25 is mixed in a mixer 26 and subsequently distributed via valves 27 and 28 to the chambers 11, 12 or the steam feeders 21, 22.

[0065] The large chamber 21 near the inlet leads to a lower concentration of the sulfide. The lower sulfide concentration in this chamber 21 in comparison with the high inlet concentration has the advantage that the corrosive attack on the reactor material, together with an operating temperature controlled by means of the steam system 20, is less.

[0066] The temperature control by means of the steam system 20 takes place by the temperature measurement of the chambers 11, 12 respectively provided with steam feeders 21, 22 and controls the quantity (quantities) of fed steam. At the same time, an outlet temperature is set. For this reason, a control cascade is used. The temperature at the top of the oxidation reactor 10 is in this case compared with the temperatures in the chambers 11, 12 with the steam feeders 21, 22, and the measured temperature in the chambers 11, 12 with the steam feeders 21, 22 limits the fed quantity of steam. By means of the temperature indicator control, the temperature of the lowermost chamber 11 is set to a setpoint value, while a maximum temperature must not be exceeded. The setpoint value is in turn set by a second controller, which controls the outlet temperature at the top of the oxidation reactor 10.

[0067] The oxidation reactor 10 is fed a feed 4, which is typically two-phase and is formed by waste lye 5 removed from a tank 30 and air 6. In the example represented, the feed 4 is fed to the oxidation reactor 10 at ambient temperature and at 20 to 40 bar. A typically three-phase component mixture 4 is removed from the oxidation reactor 10. A flow of this component mixture from the oxidation reactor 10 is set by means of a valve 40, which is likewise operated in a temperature-controlled manner.

[0068] In FIG. 2, a section of an oxidation reactor for use in an installation according to a configuration of the present invention is schematically illustrated in a greatly simplified form and, as in FIG. 1, is denoted overall by 10. The oxidation reactor 10 has a wall 210, which encloses an interior space 220 of the oxidation reactor 10. A waste lye or a mixture of waste lye and air may be received in the interior space 220 and conducted for example substantially in the direction of the arrows respectively indicated by 230.

[0069] As mentioned, in particular the oxidation air and the waste lye may be heated up before being fed into the oxidation reactor 10. Additional heating may take place by means of a stream of steam 240, which is introduced into the oxidation reactor 100 or into the waste lye received in the latter, as illustrated here by means of a steam feeding device 21. The steam feeding device 22 that is represented in FIG. 1 may be formed identically.

[0070] The steam feeding device 10 in this case comprises a cylindrical section 211, which has a centre axis 212, which may in particular correspond overall to a centre axis of the oxidation reactor 10. The cylindrical section 211 comprises a wall 213. The centre axis 212 is aligned perpendicularly. Arranged in the wall 213 are a number of openings 214, which are only partially provided with designations. The openings 214 are arranged in numbers of groups, each of the groups comprising numbers of openings 214 and the numbers of openings of each of the groups being arranged in one or more planes, which have been illustrated here by dashed lines and are denoted by 215.

[0071] The planes 215 are in each case aligned perpendicularly to the centre axis 212. In other words, the centre axis 212 intersects the planes 215 perpendicularly. In this way, numbers of rows of openings 214 or rows of holes are formed within the context of the present invention, allowing condensate to build up in the cylindrical section 211, and steam only being introduced into the interior space 220 of the oxidation reactor 10, or into the waste lye present there, through the openings 14 that remain free. In this way, a corresponding oxidation reactor 10 can be operated in an optimized manner, as repeatedly explained above.

[0072] As explained, the openings 214 in the various planes 215 are provided in the same or different numbers, in a plane 215 represented here at the top in particular it only being possible for a relatively small number of openings to be provided, in order to make a minimum load possible. For the distances 10 and 11 of the individual planes 214 from one another and with respect to the cylindrical section 211, reference should be made expressly to the above explanations.

[0073] At a lower end or first end, the cylindrical section 211 is closed by a terminating area 216, in which at least one further opening 217 is arranged. At an opposite second end of the cylindrical section 211, the latter is connected to a steam supply line 218, which may have a diameter that is the same as or different from the cylindrical section. The row of openings 214 lying nearest the steam supply line 218 advantageously has in this case the smallest number of openings 214. The formation and alignment of the respective openings 214 have been explained in detail above. The steam supply line 218 is closed at one end by a closure, or it has one or more further openings 220.

[0074] In FIG. 3A, the steam feed device 21, which is already illustrated in FIG. 2 as part of the oxidation reactor 100, is represented in a different perspective, here a plan view along the axis 212 according to FIG. 2 being illustrated from below. As represented here, the openings 214 are in this case arranged in the cylindrical section 211 in such a way that an outflow direction for steam that is defined by them deviates from a centre axis of the steam supply line 218.

[0075] If in this case, as shown in the example represented in FIG. 3A, three openings are illustrated in a plane, an intermediate angle between them is 120, and they are inclined at the angle represented of 60 with respect to a perpendicular to the centre axis of the supply line 218.

[0076] In FIG. 3B, the corresponding conditions already represented in FIG. 3A are represented for the case where four openings 214 are provided in a plane 215 of a corresponding cylindrical section 211.