A METHOD AND AN APPARATUS FOR SEPARATING CHLORINE GAS FROM A GASEOUS ANODE OUTLET STREAM OF AN ELECTROCHEMICAL REACTOR

Abstract

The invention relates to a method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor. In a first aspect, the method makes use of an absorption step, wherein an anode outlet stream mass flow of the electrochemical cell reactor is exposed to an organic solvent being essentially immiscible with water for achieving an exergy-efficient separation of chlorine and hydrogen chloride. In a further aspect, the method makes use of absorption step, wherein the anode outlet stream mass flow is exposed to an ionic liquid, wherein the hydrogen chloride is dissolved in said ionic liquid, thereby forming a gas flow containing essentially chlorine and a solution mass flow comprising the ionic liquid and the hydrogen chloride. The hydrogen chloride is desorbed from the solution mass flow in a desorption step. In another aspect, the method makes use of a distillation step, wherein the anode outlet stream mass flow is separated at a static pressure of at least 2 bar for an exergy-efficient separation.

Claims

1-15. (canceled)

16. A method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor, said anode outlet stream mass flow essentially comprising chlorine and anhydrous hydrogen chloride, comprising the following steps: a) an absorption step, wherein the anode outlet stream mass flow is exposed to an organic solvent, thereby forming a solution mass flow comprising the organic solvent containing the chlorine and a part of the hydrogen chloride, the chlorine and the part of hydrogen chloride being both dissolved in said organic solvent and a gas flow containing essentially hydrogen chloride, b) an extraction step, wherein the solution mass flow obtained in a) is exposed to a water mass flow, thereby forming an aqueous hydrogen chloride mass flow comprising essentially the water mass flow and hydrogen chloride extracted from said solution and a purified solution mass flow composed of the organic solvent and the chlorine, c) a desorption step, wherein the chlorine is desorbed from the purified solution mass flow obtained in b), whereby said organic solvent is essentially immiscible with water.

17. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16 wherein the organic solvent is a nonpolar organic solvent.

18. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16 whereby the separated hydrogen chloride is at least partly recycled to the inlet of the anode of the electrochemical cell reactor.

19. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16 whereby the separated hydrogen chloride is at least partly converted into a concentrated hydrochloric acid.

20. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16, wherein the desorption step c) is a distillation step.

21. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16 wherein said outlet stream contains chlorine according to a conversion rate of hydrogen chloride to chlorine ranging from 50% to 80%.

22. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 16 wherein the purity of the separated chlorine is at least 98%.

23. A method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor, said anode outlet stream mass flow essentially comprising chlorine and anhydrous hydrogen chloride, comprising the following steps: a) an absorption step wherein the anode outlet stream mass flow is exposed to an ionic liquid, thereby forming a solution mass flow comprising the ionic liquid containing the hydrogen chloride dissolved in said ionic liquid, and a gas flow containing essentially chlorine, and b) a desorption step wherein the hydrogen chloride is desorbed from the solution mass flow obtained by reduction of pressure and/or raising the temperature, thus, obtaining gaseous hydrogen chloride.

24. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 23 whereby the separated hydrogen chloride is at least partly recycled to the inlet of the anode of the electrochemical cell reactor.

25. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 23 whereby the separated hydrogen chloride is at least partly converted into a concentrated hydrochloric acid.

26. (canceled)

27. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 23 wherein the purity of the separated chlorine is at least 98%.

28. A method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor, said anode outlet stream mass flow essentially comprising chlorine and anhydrous hydrogen chloride, said method comprising a distillation step, wherein the anode outlet stream mass flow is separated at a static pressure of at least 2 bar, thereby forming an overhead product mass flow comprising the gaseous hydrogen chloride and a bottom product mass flow comprising the chlorine, whereby the separated hydrogen chloride is at least partially recycled to the inlet of the anode of the electrochemical all reactor and wherein the condenser temperature in the distillation column used in the distillation step is above 195 K, and whereby the separated hydrogen chloride is at least partly converted into a concentrated hydrochloric acid.

29. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 28 wherein the static pressure is at least 4 bar.

30. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 28 wherein said outlet stream contains chlorine according to a conversion rate of hydrogen chloride to chlorine ranges from 50% to 80%.

31. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 28 wherein the purity of the separated chlorine is at least 98%.

32. An apparatus for separating chlorine from a gaseous anode outlet stream mass flow comprising an electrochemical reactor having an anode outlet of a gaseous anode outlet stream comprising chlorine and hydrogen chloride, a cathode outlet stream, an anode inlet and a cathode inlet; a first absorber connected with the outlet of a gaseous anode outlet stream by a gaseous anode outlet stream line allowing absorption of chlorine in a non-polar organic solvent introduced into the absorber by a solvent providing inlet, the absorber has an inlet for introducing the gaseous anode outlet stream into the absorber and a first outlet for a non-polar organic solvent containing essentially chlorine and a part of hydrogen chloride an a second outlet for essentially the gaseous hydrogen chloride; a device for extraction of the non-polar organic solvent containing essentially chlorine and a part of hydrogen chloride into i) an aqueous hydrogen chloride mass flow and ii) a purified, solvent mass flow containing chlorine; a desorption device for separating the chlorine from the non-polar organic solvent present in the purified solvent mass flow; optionally a second absorber connected by a line with the first absorber and/or the device for extraction for absorbing at least part of hydrogen chloride obtaining concentrated aqueous hydrogen chloride; optionally a recycling line for the transport of hydrogen chloride from the first absorber to the anode inlet of the electrochemical reactor, adapted for conducting a method according to claim 1.

33. The apparatus according to claim 32 further comprising a pressure equipment for applying pressure or vacuum in the distillation device or the absorber.

34. An apparatus for separating chlorine from a gaseous anode outlet stream mass flow comprising an electrochemical reactor having an anode outlet of a gaseous anode outlet stream comprising chlorine and hydrogen chloride, a cathode outlet stream, an anode inlet and a cathode inlet; a distillation device connected with the outlet of a gaseous anode outlet stream by a gaseous anode outlet stream line allowing distillation of the gaseous anode outlet stream into an overhead product mass flow essentially comprising gaseous hydrogen chloride and a bottom product mass flow essentially comprising chlorine; an absorber connected by a line with the head of the distillation device for absorbing at least part of hydrogen chloride present in the overhead product mass flow obtaining concentrated aqueous hydrogen chloride; a recycling line for the transport of hydrogen chloride to the anode inlet of the electrochemical reactor, and a pressure equipment for applying pressure or vacuum in the distillation device adapted for conducting a method according to claim 28.

35. The apparatus according to claim 34 further comprising a pressure equipment for applying pressure or vacuum in the distillation device or the absorber.

36. Apparatus for separating chlorine from a gaseous anode outlet stream mass flow comprising an electrochemical reactor having an anode outlet of a gaseous anode outlet stream essentially comprising chlorine and hydrogen chloride, a cathode outlet stream, an anode inlet and a cathode inlet; a first absorber connected with the outlet of a gaseous anode outlet stream by a gaseous anode outlet stream line allowing absorption of hydrogen chloride in an ionic liquid introduced into the absorber by an ionic liquid providing inlet, the absorber has an inlet for introducing the gaseous anode outlet stream into the absorber and a first outlet for the ionic liquid containing hydrogen chloride and a second outlet for essentially the gaseous chlorine; a desorption device for separating the hydrogen chloride from the ionic liquid present in the solvent mass flow; a recycling line for the transport of hydrogen chloride from the desorption device to the anode inlet or the electrochemical reactor, adapted for conducting a method according to claim 2.

37. The apparatus according to claim 36 further comprising a pressure equipment for applying pressure or vacuum in the distillation device or the absorber.

38. The method for separating chlorine from a gaseous anode outlet stream mass flow according to claim 23 wherein said outlet stream contains chlorine according to a conversion rate of hydrogen chloride to chlorine ranging from 50% to 80%.

Description

[0060] In the following, examples of embodiments of the invention are discussed, making reference to the following drawings. The drawings show as follows:

[0061] FIG. 1: FIG. 1 shows a first example of an embodiment according to the invention,

[0062] FIG. 2: FIG. 2 shows a second example of an embodiment according to the invention,

[0063] FIG. 3: FIG. 3 shows a third example of an embodiment according to the invention.

[0064] FIG. 1 shows an apparatus 1 for separating chlorine from a gaseous anode outlet stream mass flow. The apparatus comprises an electrochemical reactor 2. The electrochemical reactor 2 comprises an anode-side half-cell 3 and a cathode-side half-cell 4 being separated by a membrane 5. The membrane 5 is permeable for protons and impermeable for hydrogen chloride and chlorine. Such membranes are known and commercially available, for example under the trade mark NAFION. The membrane 5 carries out the function of an electrolyte for the transport of protons between the half-cells 3, 4.

[0065] The electrochemical cell reactor 2 comprises an anode inlet 6a for introducing a gaseous hydrogen chloride mass flow 7 into the anode-side half-cell 3 and a cathode inlet 6b for introducing a cathode-gas mass flow 8 into the cathode-side half-cell 4. The cathode-gas mass flow 8 may comprise or consist of oxygen. Alternatively, protons are reduced to hydrogen. In the anode-side half-cell 3, the gaseous hydrogen chloride mass flow 7 is oxidized by an electrical power source (not shown), thereby forming chlorine. The chlorine is discharged from the anode-side half-cell 3 together with unconverted fraction of the gaseous hydrogen chloride mass flow and the chlorine forming a gaseous anode outlet stream 9. In the cathode-side half-cell 4 at least a part or all of the oxygen and the protons form water which is discharged in the form of a cathode outlet stream 4a through a cathode outlet stream line 4b. Alternatively, the hydrogen is obtained from reducing the protons at the cathode

[0066] The apparatus 1 further comprises a first absorber 10 in form of an absorption column 10. The absorption column 10 comprises an inlet 11, the gaseous anode outlet stream 9, being directed through an anode outlet stream line 12, is introduced into the absorber 10 through inlet 11. The absorber 10 also comprises a solvent providing inlet 13.

[0067] The gaseous anode outlet stream 9 is compressed by a pressure equipment 14 in the form of a compressor 14 between the outlet of the anode-side half-cell 3 and the inlet 11 of the absorption column 10, by which compressor the pressure of the gaseous anode outlet stream mass 7 flow is adjusted for the absorption step.

[0068] Due to absorption of chlorine and hydrogen chloride from the anode outlet stream 9 into the solvent being introduced through the solvent providing inlet, inside the column a gas flow 15 of hydrogen chloride and a solution mass flow 16 are formed. The solution mass flow 16 comprises the organic solvent containing, both dissolved, the chlorine and a part of the hydrogen chloride.

[0069] The absorber 10 also comprises a first outlet 17a at the bottom of the column for detaching the solution mass flow 16. At the column's head, the absorber 10 comprises a second outlet 17b for detaching the gas flow 15 containing the hydrogen chloride.

[0070] The apparatus 1 also comprises a device for extraction 18 in the form of a mixer-settler device. The device for extraction 18 comprises a water mass flow inlet 19 for introduction of a water mass flow 19a into the extraction device 18. Furthermore, the device for extraction 18 comprises a solution mass flow inlet 20 being connected to the first outlet 17a of the column 10 for introducing the solution mass flow 16 into the device for extraction 18. Due to an extraction step, the hydrogen chloride from the solution mass flow 16 is extracted into the water mass flow 19a, thereby forming an aqueous hydrogen chloride mass flow 21 and a purified solution mass flow 22. The purified solution mass flow 22 and the aqueous hydrogen chloride mass flow 21 are discharged from the device for extraction 18.

[0071] The detached purified solution mass flow 22 is charged through line 23 to a desorption device 24. Before being introduced into the desorption device 24, a pressure decrease can be applied to the purified solution mass flow 22, e.g. by a throttle. The purified solution mass flow 22 is separated by application of a distillation inside the desorption device 24, thereby forming a liquid organic solvent mass flow 25 and a gaseous chlorine mass flow 26. The organic solvent mass flow 25 is recycled through a recycling line 25a and introduced into the absorption column 10 again through the solvent providing inlet 13.

[0072] The apparatus 1 further comprises a second absorber 27 being connected by line 28 with the device for extraction 18, whereby the aqueous hydrogen chloride mass flow 21 is introduced into the second absorber 27. Furthermore, at least a part of the gas flow 15 of hydrogen chloride, being a hydrogen chloride byproduct mass flow 28a, is introduced into the second absorber 27 by a line 28b, thereby augmenting the concentration of the aqueous hydrogen chloride mass flow 21 by an additional absorption of gaseous hydrogen chloride from the hydrogen chloride byproduct mass flow 28a. By these means, a concentrated hydrochloric acid mass flow 29 is obtained as a byproduct.

[0073] The gas flow 15 of hydrogen chloride, or respectively its part not being introduced into the second absorber 27, is transported through a recycling line 30 as a recycled hydrogen chloride mass flow 30a from the second outlet 17b to the anode inlet 6a of the anode-side half-cell 3 of the electrochemical reactor 2. Formation of the recycled hydrogen chloride mass flow 30a and of the hydrogen chloride byproduct mass flow 28a is performed by splitting up the gas flow 15 by a splitter 30b.

[0074] FIG. 2 shows an apparatus 31 according to the invention. The apparatus 31 comprises an electrochemical reactor 2 according to the apparatus 1 of the first example of an embodiment. As far as the same reference numbers are used, the components referred to in this embodiment are configured in the same way as in the embodiment according to FIG. 1.

[0075] The apparatus 31 further comprises a distillation device 32 in the form of a distillation column. In this embodiment, the distillation column 32 is connected to the gaseous anode outlet stream line 12 for introducing the gaseous anode outlet stream 9 into the distillation column. The distillation step being performed in the distillation column 32 is performed at a pressure of at least 1 bar, like at least 2 bar. A pressure increase between the anode-side half-cell 4 and the distillation column 32 is applied by compressing the anode outlet stream 9 in a compressor 14. Thus, the gaseous anode outlet stream 9 is cooled, wherein the chlorine is liquefied and forms a bottom product mass flow 33 which is detached from the bottom of the distillation column 32 by line 34. The not liquefied gaseous hydrogen chloride is detached at the head of the distillation column 32. The hydrogen chloride not being liquefied forms an overhead product mass flow 35 being detached through a line 36.

[0076] Line 36 is connected with a splitter 37 allowing for transporting a part or all of the hydrogen chloride of the overhead product mass flow 35 to the anode inlet 6a of the electrochemical reactor 2 through a recycling line 38. By means of the splitter 37, a part or all of the hydrogen chloride can be introduced into an absorber 39, into which absorber also water is introduced for formation of a concentrated hydrochloric acid mass flow 40 as a byproduct.

[0077] FIG. 3 shows an apparatus 41 for separating chlorine from a gaseous anode outlet stream mass flow 9. The apparatus 41 comprises an electrochemical reactor 2 according to the apparatuses 1 and 31 of the aforementioned examples of an embodiment. As far as the same reference numbers are used, the components referred to in this embodiment are configured in the same way as in the embodiments according to FIGS. 1 and 2.

[0078] According to a further example of an embodiment, a gaseous anode outlet stream 9 is introduced into an absorber 10 through an inlet 11. In this example of an embodiment, an ionic liquid solvent mass flow 42 is introduced into the absorber 10 for absorbing the hydrogen chloride of the gaseous anode outlet stream 9, thus forming a ionic liquid solution mass flow 43 containing essentially all the hydrogen chloride. The ionic liquid solution mass flow 43 is discharged from the absorber 10 by the first outlet 17a. The gaseous chlorine of the gaseous anode outlet stream 9, being non-soluble in the ionic liquid, is detached from the absorber 10 in the form of a purified gas flow 44 at the head of the absorber 10 by the second outlet 17b.

[0079] The purified gas flow 44 can be used for chemical synthesis steps as mentioned above.

[0080] The ionic liquid solution mass flow 43 comprising the ionic liquid containing the hydrogen chloride is transported to a desorption device 45 for removing the hydrogen chloride from the ionic liquid solution mass flow 43. At least a part of the hydrogen chloride can be recycled by being transported through a recycling line 46 as a recycled hydrogen chloride mass flow 46a and being introduced into the electrochemical cell reactor 2 again.

[0081] The desorption step in the desorption device 45 is performed at a lower static pressure than the pressure in the absorber 10. The pressure decrease may be performed by a throttle or by a vacuum pump 47 between the absorber 10 and the desorption device 45. The pressure decreased ionic liquid solution mass flow 48 is introduced through a line 49 into an inlet 50 of the desorption device 45. The desorption device comprises a first outlet 51a and a second outlet 51b.

[0082] By heating the pressure decreased ionic liquid solution mass flow 43 inside the desorption device, the hydrogen chloride in the ionic liquid solution mass flow 43 is desorbed and can be discharged from the desorption device 45. The purified ionic liquid mass flow 53 being formed during the desorption step is detached from the desorption device 45 by the first outlet 51a and through a line 52. The pressure of the purified ionic liquid mass flow 53 is increased by a pump 54 and the purified ionic liquid mass flow 53 is recycled through a line 55 for getting introduced into the ionic liquid solvent mass flow 42 by a splitter 56. Thus, a circulation of the ionic liquid is achieved in the apparatus 41.

[0083] The hydrogen chloride being desorbed from the pressure decreased ionic liquid solution mass flow 48 is detached from the desorption device 45 through the second outlet 51b and through a line 57 as a gaseous purified hydrogen chloride mass flow 58. The purified hydrogen chloride mass flow 58 is compressed in a compressor 59 and introduced into a splitter 60. From the splitter 60, a part of the purified hydrogen chloride mass flow 58 may be recycled in the form of the recycled hydrogen chloride mass flow 46a through the line 46. Another part of the purified hydrogen chloride mass flow 58 may be transported from the splitter 60 through a line 61, forming a gaseous hydrogen chloride byproduct mass flow 62. The gaseous hydrogen chloride byproduct mass flow 62 is introduced into a second absorber 27 and is exposed to a water mass flow 63. The water mass flow 63 absorbs the gaseous hydrogen chloride byproduct mass flow 62, thereby forming a concentrated hydrochloric acid mass flow 64 as a byproduct.

EXAMPLES OF WORKING CONDITIONS

[0084] Given below, for each of the three embodiments according to the FIGS. 1 to 3 one set of working conditions is presented as sets of exemplary data. These data are based on a MDI production plant similar to the production plant of BASF in Antwerp applying a HCL stream of about 0.362 kmol/s.

The following exemplary data were obtained from flowsheet simulations with the program Aspen Plus V.8.8. In these simulations, the single pass conversion of the electrochemical cell reactor, as well as the overall conversion of hydrogen chloride in the process was set to 80%. Therefore, in these specific examples, no hydrogen chloride recycle towards the electrochemical reactor was employed, but the remaining 20% were dissolved in water forming concentrated hydrochloric acid. The amount of Oxygen fed into the cathode-side half-cell of the electrochemical cell reactor was enough to stoichiometrically convert all the employed hydrogen chloride to chlorine. Since only a hydrogen chloride conversion of 80% is simulated, this means that an oxygen surplus of ca. 10% is employed in these specific examples

[0085] Hydrogen Chloride Mass Flow 7:

TABLE-US-00001 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 0.36 0.00 0.36 0.00 0.00 mass flow [kg/sec] 13.20 0.00 13.20 0.00 0.00 mole fraction [-] 1.0 0.00 1.00 0.00 0.00 mass fraction [-] 1.0 0.00 1.00 0.00 0.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

Cathode Gas Mass Flow 8:

[0086]

TABLE-US-00002 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 9 .Math. 10.sup.2 0.00 0.00 0.00 9 .Math. 10.sup.2 mass flow [kg/sec] 2.88 0.00 0.00 0.00 2.88 mole fraction [-] 1.0 0.00 0.00 0.00 1.00 mass fraction [-] 1.0 0.00 0.00 0.00 1.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

Gaseous Anode Outlet Stream 9:

[0087]

TABLE-US-00003 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 0.22 0.15 0.07 0.00 0.00 mass flow [kg/sec] 12.91 10.27 2.64 0.00 0.00 mole fraction [] 1.00 0.67 0.33 0.00 0.00 mass fraction [] 1.00 10.27 2.64 0.00 0.00 temperature [K] 313.15 Pressure [Pa] 1.01 .Math. 10.sup.5

Cathode Outlet Stream 4a

[0088]

TABLE-US-00004 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 0.16 0.00 0.00 0.14 0.02 mass flow [kg/sec] 3.17 0.00 0.00 2.61 0.56 mole fraction [] 1.00 0.00 0.00 0.89 0.11 mass fraction [] 1.00 0.00 0.00 0.82 0.18 temperature [K] 313.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0089] In the following examples, the hydrogen chloride mass flow 7, the cathode gas mass flow 8, the gaseous anode outlet stream 9 and the cathode outlet stream 4a have the same properties.

[0090] The exergy consumption of the electrochemical reactor in each example is about 25.04 MW.

EXAMPLE 1

[0091] For the present example of the process involving an absorption step with an organic solvent, n-octane was chosen as organic solvent. The example relates to a setup according to FIG. 1. The streams according to the process flow chart in FIG. 1 are as follows using 02 as cathode inlet gas:

Gas Flow 15:

[0092]

TABLE-US-00005 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 3.46 .Math. 10.sup.2 4.54 .Math. 10.sup.6 3.45 .Math. 10.sup.2 2.36 .Math. 10.sup.6 0.00 9.04 .Math. 10.sup.5 mass flow [kg/sec] 1.27 3.22 .Math. 10.sup.2 1.26 4.25 .Math. 10.sup.5 0.00 1.03 .Math. 10.sup.2 mole fraction [] 1.00 1.31 .Math. 10.sup.4 0.10 6.82 .Math. 10.sup.5 0.00 2.61 .Math. 10.sup.3 mass fraction [] 1.00 2.54 .Math. 10.sup.4 0.99 3.35 .Math. 10.sup.5 0.00 8.14 .Math. 10.sup.3 temperature [K] 298.2938 Pressure [Pa] 8.11 .Math. 10.sup.5

Solution Mass Flow 16:

[0093]

TABLE-US-00006 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.45 0.14 3.79 .Math. 10.sup.2 1.08 .Math. 10.sup.4 0.00 0.27 mass flow [kg/sec] 42.48 10.27 1.38 1.94 .Math. 10.sup.3 0.00 30.83 mole fraction [] 1.00 0.32 8.37 .Math. 10.sup.2 2.38 .Math. 10.sup.4 0.00 0.60 mass fraction [] 1.00 0.24 3.25 .Math. 10.sup.2 4.57 .Math. 10.sup.5 0.00 0.73 temperature [K] 331.54 Pressure [Pa] 8.11 .Math. 10.sup.5

[0094] Water Mass Flow 19a:

TABLE-US-00007 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.25 0.00 0.00 0.25 0.00 0.00 mass flow [kg/sec] 4.50 0.00 0.00 4.50 0.00 0.00 mole fraction [] 1.00 0.00 0.00 1.00 0.00 0.00 mass fraction [] 1.00 0.00 0.00 1.00 0.00 0.00 temperature [K] 298.34 Pressure [Pa] 8.11 .Math. 10.sup.5

Aqueous Hydrogen Chloride Mass Flow 21:

[0095]

TABLE-US-00008 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.288 8.73 .Math. 10.sup.4 3.79 .Math. 10.sup.2 0.25 0.00 2.48 .Math. 10.sup.8 mass flow [kg/sec] 5.83 mole fraction [] 1.00 mass fraction [] 1.00 temperature [K] 308.15 Pressure [Pa] 8.11 .Math. 10.sup.5

[0096] Purified Solution Mass Flow 22:

TABLE-US-00009 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.41 0.14 0.00 1.35 .Math. 10.sup.4 0.00 0.27 mass flow [kg/sec] 41.05 10.21 0.00 2.43 .Math. 10.sup.3 0.00 30.84 mole fraction [] 1.00 0.35 0.00 3.26 .Math. 10.sup.4 0.00 0.65 mass fraction [] 1.00 0.25 0.00 5.93 .Math. 10.sup.5 0.00 0.75 temperature [K] 300.00 Pressure [Pa] 8.11 .Math. 10.sup.5

[0097] Chlorine Mass Flow 26:

TABLE-US-00010 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.14 0.14 0.00 2.48 .Math. 10.sup.5 0.00 7.72 .Math. 10.sup.7 mass flow [kg/sec] 10.21 10.21 0.00 4.46 .Math. 10.sup.4 0.00 8.81 .Math. 10.sup.5 mole fraction [] 1.00 0.10 0.00 1.72 .Math. 10.sup.4 0.00 5.36 .Math. 10.sup.6 mass fraction [] 1.00 0.10 0.00 4.37 .Math. 10.sup.5 0.00 8.64 .Math. 10.sup.6 temperature [K] 244.09 Pressure [Pa] 1.01 .Math. 10.sup.5

[0098] Organic Solvent Mass Flow 25:

TABLE-US-00011 in total Cl.sub.2 HCl H.sub.2O O.sub.2 n-octane mole flow [kmol/sec] 0.27 3.79 .Math. 10.sup.5 0.00 1.10 .Math. 10.sup.4 0.00 0.27 mass flow [kg/sec] 30.85 2.69 .Math. 10.sup.3 0.00 1.99 .Math. 10.sup.3 0.00 30.84 mole fraction [] 1.00 1.40 .Math. 10.sup.4 0.00 4.08 .Math. 10.sup.4 0.00 0.10 mass fraction [] 1.00 8.72 .Math. 10.sup.5 0.00 6.44 .Math. 10.sup.5 0.00 0.10 temperature [K] 395.03 Pressure [Pa] 1.01 .Math. 10.sup.5

[0099] Concentrated Aqueous Hydrogen Chloride Mass Flow 29:

TABLE-US-00012 in total Cl.sub.2 HCl H.sub.2O H.sub.3O.sup.+ Cl.sup. mole flow [kmol/sec] 0.32 4.64 .Math. 10.sup.5 .sup.5.35 .Math. 10.sup.10 0.18 7.24 .Math. 10.sup.2 7.24 .Math. 10.sup.2 mass flow [kg/sec] 7.14 3.29 .Math. 10.sup.3 1.95 .Math. 10.sup.8 3.19 1.38 2.57 mole fraction [] 1.00 1.44 .Math. 10.sup.4 1.66 .Math. 10.sup.9 0.55 0.22 0.22 mass fraction [] 1.00 4.60 .Math. 10.sup.4 2.73 .Math. 10.sup.9 0.45 0.19 0.36 temperature [K] 307.10 Pressure [Pa] 1.01 .Math. 10.sup.5

[0100] In this example, the absorber 10 is an absorption column with 16 stages (or an equivalent height in the case of a packing column). The absorption step is carried out at 8.10 bar and with a top stage temperature of 298.3 K and a bottom stage temperature of 331.50 K.

[0101] The extraction step in the extraction device 18 is carried out with a temperature of the water and hydrogen chloride phase of 308.15 K and a temperature of the octane phase of 300 K.

[0102] The desorption step is carried out in the desorption device 24 with a condenser temperature of 244 K and a sump temperature of 395 K.

[0103] Absorption of hydrogen chloride in the second absorber 27 is carried out with a temperature of 308.15 K.

[0104] In this embodiment, the exergy consumption of the method for separating the chlorine and the production of the hydrochloric acid is about 2 MW.

[0105] The exergy consumption of the overall process is about 27.04 MW which is about 36% lower than the exergy consumption of about 42.27 MW of the Bayer UHDENORA process as described in U.S. Pat. No. 8,153,938 B2 and based on the public data sheets by Thyssen, e.g. as published in Hydrochloric acid electrolysis sustainable chlorine production, ThyssenKrupp Uhde GmbH, 2012.

EXAMPLE 2

[0106] For the present example of the process involving an absorption step with an ionic liquid, diethyl-methylsulfonium methanesulfonate ([S221][MeSO3]) was chosen as ionic liquid. The example relates to a setup according to FIG. 3. The most important streams according to the process flow chart in FIG. 3 are as follows:

[0107] Ionic Liquid Solvent Mass Flow 42:

TABLE-US-00013 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] .sup.5.79 .Math. 10.sup.3 5.75 .Math. 10.sup.9 7.87 .Math. 10.sup.4 5.01 .Math. 10.sup.3 mass flow [kg/sec] 1.04 9.93 .Math. 10.sup.7 0.14 0.86 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0108] Ionic Liquid Solution Mass Flow 43:

TABLE-US-00014 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] .sup.7.92 .Math. 10.sup.2 1.63 .Math. 10.sup.3 7.25 .Math. 10.sup.2 5.01 .Math. 10.sup.3 mass flow [kg/sec] 3.77 mole fraction [] 1.00 2.06 .Math. 10.sup.2 0.92 6.32 .Math. 10.sup.2 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0109] Purified Gas Flow 44:

TABLE-US-00015 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] 0.14 0.14 6.53 .Math. 10.sup.4 0.00 mass flow [kg/sec] 10.18 mole fraction [] 1.00 1.00 4.54 .Math. 10.sup.3 0.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0110] Pressure Decreased Ionic Liquid Solution Mass Flow 48:

TABLE-US-00016 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] 7.92 .Math. 10.sup.2 1.63 .Math. 10.sup.3 7.25 .Math. 10.sup.2 5.01 .Math. 10.sup.3 mass flow [kg/sec] 3.77 mole fraction [] 1.00 2.06 .Math. 10.sup.2 0.92 6.32 .Math. 10.sup.2 temperature [K] 298.15 Pressure [Pa] 5066.25

[0111] Purified Ionic Liquid Mass Flow 53:

TABLE-US-00017 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] 5.79 .Math. 10.sup.3 5.76 .Math. 10.sup.3 7.87 .Math. 10.sup.4 5.01 .Math. 10.sup.3 mass flow [kg/sec] 1.04 mole fraction [] 1.00 9.93 .Math. 10.sup.7 0.14 0.86 temperature [K] 483.15 Pressure [Pa] 5066.25

[0112] Purified Hydrogen Chloride Mass Flow 58:

TABLE-US-00018 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] 7.34 .Math. 10.sup.2 1.63 .Math. 10.sup.3 7.17 .Math. 10.sup.2 2.38 .Math. 10.sup.22 mass flow [kg/sec] 2.73 mole fraction [] 1.00 2.23 .Math. 10.sup.2 0.98 3.24 .Math. 10.sup.21 temperature [K] 483.15 Pressure [Pa] 5066.25

[0113] Gaseous Hydrogen Chloride Byproduct Mass Flow 62:

TABLE-US-00019 Ionic in total Cl.sub.2 HCl liquid mole flow [kmol/sec] .sup.7.34 .Math. 10.sup.2 1.63 .Math. 10.sup.3 7.17 .Math. 10.sup.2 2.38 .Math. 10.sup.22 mass flow [kg/sec] 2.73 mole fraction [] 1.00 2.23 .Math. 10.sup.22 0.98 3.24 .Math. 10.sup.21 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0114] Since no recycled hydrogen chloride mass flow 46a is provided, the composition of the gaseous hydrogen chloride byproduct mass flow 62 corresponds to the composition of the purified hydrogen chloride mass flow 58 but may have a higher temperature and a higher pressure due to compression by the compressor 59 and eventually additional heating by a heat exchanger 65.

[0115] Water Mass Flow 63:

TABLE-US-00020 in total Cl.sub.2 HCl Ionic liquid H.sub.2O mole flow [kmol/sec] 0.25 0.00 0.00 0.00 0.25 mass flow [kg/sec] 4.44 0.00 0.00 0.00 4.44 mole fraction [] 1.00 0.00 0.00 0.00 1.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

Hydrogen Chloride Mass Flow 64:

[0116]

TABLE-US-00021 in total Cl.sub.2 HCl H.sub.2O H.sub.3O.sup.+ Cl.sup. mole flow [kmol/sec] 0.32 0.00 .sup.5.38 .Math. 10.sup.10 0.17 7.17 .Math. 10.sup.2 7.17 .Math. 10.sup.2 mass flow [kg/sec] 7.05 0.00 .sup.1.96 .Math. 10.sup.8 3.14 1.36 2.54 mole fraction [] 1.00 0.00 1.69 .Math. 10.sup.9 0.55 0.23 0.23 mass fraction [] 1.00 0.00 2.78 .Math. 10.sup.9 0.45 0.19 0.36 temperature [K] 308.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0117] In this example, the absorption step is carried out at a temperature of 298.15 K in a single stage absorber. The vacuum pump 47 and/or a throttle valve in combination with the compressor 59 does provide a vacuum with a pressure of 0.05 bar at its outlet.

[0118] The compressor 54 provides a pressure of 1.013 bar for recycling the ionic liquid through line 55 and into the splitter 56.

[0119] The compressor 59 provides a four-stage compression of the purified hydrogen chloride mass flow 58, i.e. from 0.05 bar to 0.1 bar by the first compression stage, from 0.1 to 0.2 bar by the second compression stage, from 0.2 to 0.4 bar by the third compression stage and from 0.4 to 1.013 bar by the fourth compression stage. After being compressed to a pressure of 1.013 bar or 1 atm, the compressed purified hydrogen chloride mass flow 58 is cooled by the heat exchanger 65 before being introduced into the second absorber 27.

[0120] In the second absorber 27, absorption of hydrogen chloride is carried out at a temperature of 308.15 K and at a pressure of 1.013 bar.

[0121] In this embodiment, the exergy consumption of the method for separating the chlorine and the production of the hydrochloric acid is about 1.96 MW.

[0122] The exergy consumption of the overall process is about 27.00 MW which is about 36% lower than the exergy consumption of about 42.25 MW of the Bayer UHDENORA process.

EXAMPLE 3

[0123] The example relates to a setup according to FIG. 2. For the process involving a distillation step, the distillation was carried out at 1 atmospheric pressure. The most important streams according to the process flow chart in FIG. 2 are as follows:

[0124] Bottom product mass flow 33 being discharged from distillation column 32:

TABLE-US-00022 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 0.14 0.14 5.04 .Math. 10.sup.5 0.00 0.00 mass flow [kg/sec] 10.27 10.26 1.84 .Math. 10.sup.3 0.00 0.00 mole fraction [] 1.00 0.10 3.48 .Math. 10.sup.4 0.00 0.00 mass fraction [] 1.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0125] Overhead Product Mass Flow 35 being Discharged from Distillation Column 32:

TABLE-US-00023 in total Cl.sub.2 HCl H.sub.2O O.sub.2 mole flow [kmol/sec] 7.24 .Math. 10.sup.2 4.31 .Math. 10.sup.5 7.24 .Math. 10.sup.2 0.00 0.00 mass flow [kg/sec] 2.64 3.06 .Math. 10.sup.3 2.64 0.00 0.00 mole fraction [] 1.00 5.96 .Math. 10.sup.4 0.10 0.00 0.00 mass fraction [] 1.00 1.16 .Math. 10.sup.3 0.10 0.00 0.00 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0126] Concentrated Aqueous Hydrogen Chloride Mass Flow 40 being Discharged from Distillation Column 32:

TABLE-US-00024 in total Cl.sub.2 HCl H.sub.2O H.sub.3O.sup.+ Cl.sup. mole flow [kmol/sec] 0.32 4.31 .Math. 10.sup.5 7.05 .Math. 10.sup.10 0.18 7.24 .Math. 10.sup.2 7.24 .Math. 10.sup.2 mass flow [kg/sec] 7.11 3.06 .Math. 10.sup.3 2.57 .Math. 10.sup.8 3.17 1.38 2.57 mole fraction [] 1.00 1.35 .Math. 10.sup.4 2.20 .Math. 10.sup.9 0.55 0.23 0.23 mass fraction [] 1.00 4.30 .Math. 10.sup.4 3.62 .Math. 10.sup.9 0.45 0.19 0.36 temperature [K] 298.15 Pressure [Pa] 1.01 .Math. 10.sup.5

[0127] In this example, the distillation device 32 is a distillation column with 16 stages (or in the case of a packed column with a height being equivalent to 16 stages). The distillation column 32 is operated with a condenser temperature of 187.3 K at the column's head and with a sump temperature of 239.4 K at the bottom of the column.

[0128] In this embodiment, the exergy consumption of the method for separating the chlorine and the production of the hydrochloric acid is about 1.22 MW.

[0129] The exergy consumption of the overall process is about 26.26 MW which is about 38% lower than the exergy consumption of about 42.25 MW of the Bayer UHDENORA process

REFERENCES

[0130] 1 apparatus [0131] 2 electrochemical reactor [0132] 3 anode-side half-cell [0133] 4 cathode-side half-cell [0134] 4a cathode outlet stream [0135] 4b cathode outlet stream line [0136] 5 membrane [0137] 6a anode inlet [0138] 6b cathode inlet [0139] 7 gaseous hydrogen chloride mass flow [0140] 8 cathode gas mass flow [0141] 9 gaseous anode outlet stream [0142] 10 absorber [0143] 11 inlet [0144] 12 anode outlet stream line [0145] 13 solvent providing inlet [0146] 14 compressor [0147] 15 gas flow [0148] 16 solution mass flow [0149] 17a first outlet [0150] 17b second outlet [0151] 18 device for extraction [0152] 19 water mass flow inlet [0153] 20 solution mass flow inlet [0154] 21 aqueous hydrogen chloride mass flow [0155] 22 purified solution mass flow [0156] 23 line [0157] 24 desorption device [0158] 25 organic solvent mass flow [0159] 25a recycling line [0160] 26 chlorine mass flow [0161] 27 second absorber [0162] 28 line [0163] 28a hydrogen chloride byproduct mass flow [0164] 28b line [0165] 29 concentrated aqueous hydrogen chloride mass flow [0166] 30 recycling line [0167] 30a recycled hydrogen chloride mass flow [0168] 30b splitter [0169] 31 apparatus [0170] 32 distillation device [0171] 33 bottom product mass flow [0172] 34 line [0173] 35 overhead product mass flow [0174] 36 line [0175] 37 splitter [0176] 38 recycling line [0177] 39 absorber [0178] 40 concentrated aqueous hydrogen chloride mass flow [0179] 41 apparatus [0180] 42 ionic liquid solvent mass flow [0181] 43 ionic liquid solution mass flow [0182] 44 gas flow [0183] 45 desorption device [0184] 46 recycling line [0185] 46a recycled hydrogen chloride mass flow [0186] 47 vacuum pump [0187] 48 pressure decreased ionic liquid solution mass flow [0188] 49 line [0189] 50 inlet [0190] 51a first outlet [0191] 51b second outlet [0192] 52 line [0193] 53 purified ionic liquid mass flow [0194] 54 pump [0195] 55 line [0196] 56 splitter [0197] 57 line [0198] 58 purified hydrogen chloride mass flow [0199] 59 compressor [0200] 60 splitter [0201] 61 line [0202] 62 hydrogen chloride byproduct mass flow [0203] 63 water mass flow [0204] 64 concentrated hydrochloric acid mass flow [0205] 65 heat exchanger