Abstract:
A method includes injecting a feed stream including a hydrogen halide and water into a vapor liquid separator. The feed stream has a liquid phase and a vapor phase. The method further includes separating the liquid phase and the vapor phase in the vapor liquid separator to form condensate and vapor, and discharging the condensate from the vapor liquid separator in a liquid stream. The method also includes discharging the vapor from the vapor liquid separator in a vapor stream.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Application No. 61/828,826, filed May 30, 2013 entitled “HBr Recovery by Partial Condensation,” the entire disclosure of which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to the recovery of halogens from streams that include water. 
       BACKGROUND 
       [0003]    Halogenated compounds are used in a variety of industrial processes. In certain of these processes, hydrogen halides are formed. In some instances, dilute hydrogen halide may be concentrated in a distillation system and recovered to avoid discharging the dilute hydrogen halide from the industrial process. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The present disclosure is best understood from the detailed description when read with the accompanying figures. In accordance with the standard practice in the industry, various features are not drawn to scale. 
           [0005]      FIG. 1  is a process flow diagram consistent with at least one embodiment of the present disclosure. 
           [0006]      FIG. 2  is a VLE diagram of hydrogen bromide at 12 bar. 
           [0007]      FIG. 3  is a VLE diagram of hydrogen chloride at 12 bar. 
           [0008]      FIG. 4  is a VLE diagram of hydrogen iodide at 12 bar. 
           [0009]      FIG. 5  is a process flow diagram consistent with at least one embodiment of the present disclosure. 
           [0010]      FIG. 6  is a process flow diagram consistent with at least one embodiment of the present disclosure. 
           [0011]      FIG. 7  is a process flow diagram consistent with at least one embodiment of the present disclosure. 
           [0012]      FIG. 8  is a process flow diagram consistent with at least one embodiment of the present disclosure. 
       
    
    
     SUMMARY 
       [0013]    In an embodiment, a method is disclosed. The method includes injecting a feed stream including a hydrogen halide and water into a vapor liquid separator. The feed stream has a liquid phase and a vapor phase. The method further includes separating the liquid phase and the vapor phase in the vapor liquid separator to form condensate and vapor, and discharging the condensate from the vapor liquid separator in a liquid stream. The method also includes discharging the vapor from the vapor liquid separator in a vapor stream. 
         [0014]    In another embodiment, a method is disclosed. The method includes feeding an HBr feed stream to a first HBr oxidation reactor and combining air with the HBr feed stream in the first HBr oxidation reactor to form a first oxidation reactor discharge stream. The method also includes feeding the first oxidation reactor discharge stream to a quench cooling unit and cooling the first reactor discharge stream in the quench cooling unit by injecting water into the first reactor discharge stream to form a second HBr feed stream. In addition, the method includes feeding the second HBr feed stream to a second HBr oxidation reactor and combining air with the second HBr feed stream in the second HBr oxidation reactor to form an elevated temperature heat exchanger feed. The elevated temperature heat exchanger feed includes water, HBr, bromine, oxygen, and nitrogen. The method also includes cooling the elevated temperature heat exchanger feed in a heat exchanger to form an elevated temperature mixer feed and mixing the elevated temperature mixer feed in a mixer with water to form a vapor liquid separator feed stream. The method further includes feeding the vapor liquid separator feed stream to a vapor liquid separator and separating the vapor liquid feed stream in the vapor liquid separator into a vapor liquid separator liquid stream and a vapor liquid separator vapor stream, wherein the vapor liquid separator liquid stream includes HBr. In addition, the method includes feeding the vapor liquid separator vapor stream to a cooling condensation unit and forming a cooling condensation unit discharge stream in the cooling condensation unit. The method also includes feeding the cooling condensation unit discharge stream to a separator to form a recycle water stream, a bromine stream and a light gas stream. 
       DETAILED DESCRIPTION 
       [0015]    The following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
         [0016]      FIG. 1  is a process flow diagram depicting partial condensation system  10  consistent with certain embodiments of the present disclosure. Partial condensation system  10  includes vapor liquid separator  20 , VLS feed  30 , VLS vapor stream  40 , and VLS liquid stream  50 . 
         [0017]    VLS feed  30  may include a hydrogen halide, including hydrogen chloride, hydrogen bromide and hydrogen iodide, and water. In addition to the hydrogen halide and water, VLS feed  30  may include a halogen, oxygen, nitrogen, argon, carbon dioxide, and other gases. VLS vapor stream  40  may include the hydrogen halide, the halogen, water, oxygen, nitrogen, argon, carbon dioxide, and other gases. VLS liquid stream  50  may include the hydrogen halide, water, and the halogen. In certain embodiments, greater than 70%, greater than 80%, or greater than 90% of the halogen present in VLS feed  30  is in VLS vapor stream  40 . 
         [0018]    In certain embodiments of the present disclosure, the hydrogen halide content of VLS feed  30  may be substantially less than the water content of VLS feed  30 . For instance, the water content of VLS feed  30  may be between 500 and 4000 times the hydrogen halide content of VLS feed  30 , between 1000 and 3000 times the hydrogen halide content of VLS feed  30 , or between 1500 and 2500 times the hydrogen halide content of VLS feed  30  (all by weight). 
         [0019]    VLS feed  30  may be a combination of liquid and vapor. As VLS feed  30  enters vapor liquid separator  20 , the vapor portion of VLS feed  30  separates from the liquid in VLS feed  30 . The liquid, termed “condensate” in this disclosure, settles to the bottom of vapor liquid separator  20  and exits via VLS liquid stream  50 . Vapor in vapor liquid separator  20  exits via VLS vapor stream  40 . In some embodiments, a portion of the liquid in VLS feed  30  may flash and become vapor. 
         [0020]    Vapor liquid separator  20  may be a flash drum, flash pot, knock-out drum, knock-out pot, piping, distillation column, absorption column or any other vessel or equipment designed to allow a portion of a liquid in the VLS feed  30  to vaporize and exit vapor liquid separator  20  via VLS vapor stream  40 . Vapor liquid separator  20  may include a de-entrainment mesh pad (not shown) to assist in separation of liquid droplets entrained in the vapor or an inlet diffuser (not shown) to assist in distributing VLS feed  30  in vapor liquid separator  20 . 
         [0021]    One of ordinary skill in the art will recognize that the temperature, pressure and vapor/liquid distribution of VLS feed  30  may be set depending on such non-limiting factors as the type of halogen, the desired concentration of the hydrogen halide in VLS vapor stream  40 , and desired materials of construction of vapor liquid separator  20 . In certain non-limiting embodiments, the pressure in vapor liquid separator  20  may be from 1 to 20 bar, or from 1 to 15 bar, or about 12 bar. 
         [0022]    By selecting the temperature of VLS feed  30  and thereby vapor liquid separator  20 , the concentration of the hydrogen halide in VLS vapor stream  40  and in VLS liquid stream  50  may be adjusted to a desired value. In accordance with  FIGS. 2 ,  3 , and  4 , which are the vapor liquid equilibrium diagrams for hydrogen bromide, hydrogen chloride, and hydrogen iodide, respectively, by selecting the temperature of vapor liquid separator  20 , the hydrogen halide in VLS feed  30  may be concentrated in the condensate in VLS feed  30 , which exits vapor liquid separator  20  in VLS liquid stream  50 . In certain embodiments, more than 90% or more than 95% or more than 99% of the hydrogen halide present in VLS feed  30  exits vapor liquid separator  20  in VLS liquid stream  50 . In other embodiments, between 99.7% and 99.9% of the hydrogen halide present in VLS feed  30  exits vapor liquid separator  20  in VLS liquid stream  50 . 
         [0023]    In certain embodiments of the present disclosure, the amount of water in VLS feed  30  that exits vapor liquid separator  20  in VLS liquid stream  50  is less than 20%, less than 10% or less than 8% of the water in VLS feed  30 . In other embodiments, the amount of water in VLS feed  30  that exits vapor liquid separator  20  in VLS liquid stream  50  is between  6  and 8%. The concentration of water in VLS liquid stream  50  may be greater than 80%, greater than 90% or between 90 and 100% (by weight). 
         [0024]    In certain embodiments of the present disclosure, the VLS liquid stream  50  is used in a hydrogen halide oxidation process. 
         [0025]    In some embodiments of the present disclosure, it may be desirable to cool a water/hydrogen halide mixture prior to entry to vapor liquid separator  20 . For instance, as shown in  FIG. 5 , mixer  100  may be located upstream of vapor liquid separator  20 . Elevated temperature mixer feed  120  may be mixed with liquid cooling feed  110  in mixer  100  to cool the water/hydrogen halide mixture. In some such embodiments, liquid cooling feed  110  includes water. In certain embodiments, liquid cooling feed  110  may include a hydrogen halide. Liquid cooling feed  110  may be less than 100° C., less than 80° C. or less than 50° C. 
         [0026]    In other embodiments of the present disclosure, excess heat of the water/hydrogen halide mixture may be recovered through the use of a heat exchanger, such as a steam boiler. As shown in  FIG. 6 , elevated temperature heat exchanger feed  210  is sent to heat exchanger  200 , wherein the excess heat of elevated temperature heat exchanger feed  210  may be used to heat a cooling fluid, such as water. In certain such embodiments, steam formed by elevated temperature heat exchanger feed  210  may be used elsewhere in the industrial process that forms elevated temperature heat exchanger feed  210 . Heat exchanger  200  may be operated in conjunction with mixer  100  to control the amount of condensate formed in vapor liquid separator  20 . 
         [0027]      FIG. 7  depicts yet another embodiment of partial condensation system  10 , wherein mixer  100  is not used. In the embodiment shown in  FIG. 7 , heat exchanger  200  may be operated to control the amount of condensate in vapor liquid separator  20 . 
         [0028]    In certain embodiments of the present disclosure, the elevated temperature heat exchanger feed  210  is generated in an oxidation reactor. In certain other embodiments of the present disclosure, the elevated temperature mixer feed  120  is generated in an oxidation reactor. In still other embodiments of the present disclosure, VLS feed  30  is generated in an oxidation reactor. 
         [0029]      FIG. 8  depicts an embodiment of the present disclosure wherein partial condensation system  10  is a part of hydrogen bromide oxidation process  1000 . In the non-limiting embodiment depicted in  FIG. 8 , HBr feed stream  510  is sent to first HBr oxidation reactor  500  where it is combined with air  870 . The resulting first HBr oxidation discharge stream  520  may contain HBr, water, oxygen, nitrogen, CO 2  and other gases that may be found in air. First HBr oxidation discharge stream  520  is cooled in quench cooling unit  600  by direct injection of water from VLS liquid stream  50 . Second HBr feed stream  530  exits quench cooling unit  600  and is fed to second HBr oxidation reactor  550 , where it is combined with air  870 . VLS feed  30  is discharged from second HBr oxidation reactor  550  and fed to partial condensation system  10 . In alternative embodiments (not shown), elevated temperature mixer feed  120  or elevated temperature heat exchanger feed  210  may be discharged from second HBr oxidation reactor  550  in place of VLS feed  30 . As described above, VLS liquid stream  50  is discharged from vapor liquid separator  20  of partial condensation system  10  and is recycled to quench cooling unit  600 , where it is directly injected into first HBr oxidation discharge stream  520 . VLS vapor stream  40  is fed to cooling condensation unit  700 , which cools and condenses condensable compounds in VLS vapor stream  40 . Cooling condensation unit discharge stream  710  exits cooling condensation unit  700  and is separated into recycle water stream  810 , bromine stream  820  and light gas stream  830  in separator  800 . Light gas stream  830  is sent to scavenging unit  900 . In scavenging unit  900 , remaining bromine compounds are recycled through scavenging unit recycle  910  to cooling condensation unit  700 . Remaining light gases are vented from hydrogen bromide oxidation process  1000  through vent gas discharge  920 . 
         [0030]    Hydrogen bromide oxidation process  1000  generates more water than is used by hydrogen bromide oxidation process  1000 . Therefore, a portion of recycle water stream  810  is discharged through stripper feed line  840  to stripper  850 . In stripper  850 , bromine is stripped from recycle water stream  810 . Water from which bromine is stripped is discharged from stripper  850  through waste water stream  860 . 
         [0031]    A portion of recycle water stream  810  may be sent to partial condensation system  10  through liquid cooling feed  110 . In an alternative embodiment, where partial condensation system  10  does not contain mixer  100  (not shown), liquid cooling feed  110  is omitted. 
         [0032]    Embodiments of the present disclosure may be used in hydrogen halide oxidation processes including those using HBr, HCl, and HI. For instance, embodiments may be used in the oxidation of hydrogen bromine as part of a process of converting natural gas to liquid hydrocarbons as shown and described, for instance, in U.S. Pat. No. 7,579,510. U.S. Pat. No. 7,579,510 is hereby incorporated fully by reference. Embodiments of the present disclosure may be used in the oxidation of hydrogen bromine as part of a process of converting propane to propylene as shown and described in, for instance, U.S. Patent Publication No. 2012-0302808. U.S. Patent Publication No. 2012-0302808 is hereby incorporated fully by reference. 
         [0033]    Embodiments of the present disclosure may also be used in the oxidation of hydrogen chloride, such as in the process of manufacturing vinyl chloride monomer, chlorofluorocarbons, and isocyanates. Embodiments of the present disclosure may further be used in the oxidation of hydrogen iodide, such as in the process of manufacturing p-di-iodo benzene and other iodinated aromatic compounds. 
         [0034]    The above example demonstrates possible embodiments of the present disclosure. While the foregoing is directed to embodiments, versions and examples, which are included to enable a person of ordinary skill in the art to make and use the embodiments when the information in this patent is combined with available information and technology, the disclosure is not limited to only these particular embodiments, versions and examples. Other and further embodiments, versions and examples may be devised without departing from the basic scope thereof and the scope thereof is determined by the claims that follow.