Abstract:
The present invention provides a reactor for the gas-phase reaction of commercially available gases in the presence of an inert carrier gas to form product gas. The reactor has a streamlined, compact configuration and at least one solids collection and removal system downstream of the reactor, where solids are efficiently removed from the product gas stream, leaving high purity product gas. The removal system allows for a simple reactor design, which is easy to clean and operates continuously over longer periods of time.

Description:
[0001]    This application claims a benefit of priority from U.S. Provisional Application No. 60/426,104 the entire disclosure of which is herein incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a process and apparatus for producing an inorganic compound. More particularly, the present invention relates to a gas-phase process and apparatus for producing an inorganic compound, for example, chloramine gas, from commercially available gases.  
           [0004]    2. Description of the Prior Art  
           [0005]    An efficient process for forming chloramine is the reaction of chlorine gas with ammonia, as set forth in the reaction below:  
                         
 
           [0006]    Examples of this basic reaction are disclosed in U.S. Pat. No. 2,837,409 to Sisler et al. and U.S. Pat. No. 3,488,164 to Grushkin et al.  
           [0007]    The chlorine/ammonia reaction is especially effective if it is carried out by introducing gaseous chlorine into a large excess of gaseous ammonia, immediately mixing the reactants and withdrawing them from the reaction zone.  
           [0008]    Although a highly desirable reaction, there are many drawbacks associated with the reaction of gaseous chlorine and gaseous ammonia. One notable drawback is the creation of the by-product ammonium chloride. At temperatures below 350° C., ammonium chloride condenses and solids precipitate from the product gas. The solids may foul the reactor if not properly controlled. To prevent or minimize this formation of solid ammonium chloride, the reaction must take place at a temperature above 350° C.  
           [0009]    U.S. Pat. No. 4,038,372 to Colli discloses a process for manufacturing chloramine. The chloramine is formed from a gaseous reaction of chlorine and ammonia at about 360° C. The resulting product gas discharges to a discharge zone, which is heated to avoid ammonium chloride from precipitating out of the product gas. The product gas stream is then entrained in a high velocity jet of entraining gas. This gas cools the product gas stream and carries the gas stream to a filter system where the ammonium chloride solids are separated from the chloramine gas.  
           [0010]    Great Britain Patent No. 1,149,836 discloses a process for the production of chloramine. The process includes the reaction of chlorine and ammonia in the presence of an inert diluent gas. The reaction takes place at a temperature of at least 250° C. The gaseous reaction products are maintained at a temperature of about 50° C. to about 250° C. until at least a portion of the ammonium chloride is solidified. The ammonium chloride is collected on a glass wool filter, and thereafter, the gaseous chloramine is recovered, preferably in a solvent.  
           [0011]    The present invention overcomes the burdensome problem of the formation of solids by providing a novel reactor with a solids collection and removal system downstream of the reactor. This novel removal system allows for a simple reactor design, which is easy to clean and continuously operates over longer periods of time.  
         SUMMARY OF THE INVENTION  
         [0012]    It is an object of the present invention to provide a reactor for the continuous production of inorganic compounds.  
           [0013]    It is another object of the present invention to provide one or more means for removing solids from the product gas stream to avoid fouling the reactor.  
           [0014]    It is a further object of the present invention to provide such a reactor that has a simple streamlined design.  
           [0015]    It is yet a further object of the present invention to provide such a reactor that is easy to clean.  
           [0016]    It is still a further object of the present invention to provide such a reactor that has an increased continuous operation time.  
           [0017]    These and other objects of the present invention are achieved by a gas-phase reaction of commercially available feed gases in the presence of an inert carrier gas in a novel reactor to form process gas compounds. The term “feed gas” or “feed gases” is meant, for purposes of this application, to include reactive gas(es) used in the processes of the present invention. The reactor has a streamlined, compact configuration and a solids collection and removal system downstream of the reactor, where solids are efficiently removed from the product gas stream, leaving high purity product gas. This novel removal system allows for a simple reactor design, which is easy to clean and operates continuously over longer periods of time. In a preferred embodiment, the novel reactor is used to form chloramine product gas. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a plan view of a reactor according to the present invention;  
         [0019]    [0019]FIG. 2 is a plan view of a solids collection and removal system according to the present invention; and  
         [0020]    [0020]FIG. 3 is a plan view of a reactor with a split discharge line according to an embodiment of the present invention;  
         [0021]    [0021]FIG. 4 is a plan view of a solids collection and removal system with two collection units according to an embodiment of the present invention;  
         [0022]    [0022]FIG. 5 is a plan view of another embodiment of a solids collection system according to the present invention; and  
         [0023]    [0023]FIG. 6 is a graph illustrating the abundance of chloramine with relation to ammonia and chlorine in a product gas formed according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    Referring to FIG. 1, a gas-phase reactor according to the present invention is represented generally by reference numeral  10 . Reactor  10  has an outer shell tube  12  and an inner tube  16 , both of which feed reaction chamber  18 . At least one first commercially available feed gas is fed to outer tube  12  via first inlet  13 . One or more inert gases is fed to outer tube  12  via second inlet  14 . The one or more inert gases act as a diluent and as a carrier for the at least one first commercially available gas. At least one additional or second commercially available feed gas is concentrically fed (i.e., one or more feed tubes positioned within one or more additional feed tubes) to reaction chamber  18  via inner shell tube  16 . By concentrically feeding the feed gas to reaction chamber  18 , the reaction occurs immediately upon discharge of the feed gas to the reaction chamber, thus providing a more efficient reaction. As a result, a greater conversion of feed gas to product gas results, thus avoiding the undesirable formation of solids in reaction chamber  18 .  
         [0025]    Suitable commercially available feed gases for use in the reactor of the present invention include, without limitation, acetylene, ammonia, boron trichloride, boron trifluoride, butadiene, butane, butene, carbon dioxide, carbon monoxide, chlorine, cis-2-butene, deuterium, dimethylamine, dimethyl ether, ethane, ethylene, ethyl chloride, hydrogen, hydrogen bromide, hydrogen chloride, hydrogen sulfide, isobutane, isobutylene, methane, methyl bromide, methyl chloride, methyl mercaptan, methylamine, nitric oxide, nitrogen dioxide, nitrous oxide, oxygen, perfluoropropane, propane, propylene, sulfur dioxide, sulfur hexafluoride, trans-2-butene, trimethylamine, or any combinations thereof.  
         [0026]    Suitable inert gases for use in the present invention include, but are not limited to, nitrogen, argon, helium, neon, or any combinations thereof.  
         [0027]    By way of example, reactions using the novel reactor of the present invention may include, but are not limited to, the following: 
         Cl 2 +2NH 3 →NH 2 Cl+NH 4 Cl 
         NH 3 +BCl 3 →Cl 3 B—NH 3   
         SO 3 +NH 3 →SO 3 NH 3   
         Cl 2 +HBr→HCl+BrCl 
         Cl 2 +NO→NO 2 +ClNO 
         [0028]    In one embodiment of the present invention, chloramine gas is produced using the novel reactor of the present invention.  
         [0029]    Chlorine or chlorine containing gas is fed to the reactor via first inlet  13  and outer tube  12  at a flow rate about 0.001 ft 3 /min to about 0.1 ft 3 /min. Preferably, the chlorine gas is fed to the reactor at a flow rate about 0.01 ft 3 /min to about 0.05 ft 3 /min, and more preferably about 0.0125 ft 3 /min to about 0.015 ft 3 /min.  
         [0030]    The inert gas is fed to the reactor via second inlet  14  and outer tube  12  at a flow rate about 0.1 ft 3 /min to about 1 ft 3 /min. Preferably, the inert gas is fed to the reactor at a flow rate about 0.12 ft 3 /min to about 0.36 ft 3 /min, and more preferably 0.15 ft 3 /min to about 0.18 ft 3 /min.  
         [0031]    Gaseous ammonia is fed to the reactor via inner shell tube  16  at a flow rate of about 0.002 ft 3 /min to about 0.2 ft 3 /min. Preferably, the gaseous ammonia is fed to the reactor at a flow rate about 0.032 ft 3 /min to about 0.096 ft 3 /min, and more preferably about 0.04 ft 3 /min to about 0.048 ft 3 /min.  
         [0032]    A critical aspect of the present invention, when forming chloramine gas, is the pre-mixing of the chlorine gas and inert gas prior to preheating the gases. Chlorine gas by itself is highly corrosive at higher temperatures. It has been found that by mixing the chlorine gas and inert gas prior to heating reduces and/or eliminates the corrosiveness of the chlorine gas. As a result, materials that are less expensive and easier to machine can be used for making reactor  10  of the present invention.  
         [0033]    Suitable materials for constructing reactor  10  of the present invention include, but are not limited to, hastelloy C, stainless steel, brass, borosilicate glass, silicate, sodium silicate, potassium silicate, silica, or any combinations thereof. Preferably, the materials used to construct reactor  10  include hastelloy C, stainless steel, or a combination thereof.  
         [0034]    Another important aspect of the present invention is the preheating of all of the gases prior to their introduction to reaction chamber  18 . As a result of preheating the feed gases, a smaller, more compact reactor can be used without the problem of the reactor fouling with solids, such as ammonium chloride in the case of chloramine. In addition, the higher temperatures provide higher conversion rates and/or selectivity. This provides a key advantage to continuously and efficiently producing product gas.  
         [0035]    The device or element for heating the feed gases include, for example, heat tape, high resistivity wire, steam, furnace, or any combinations thereof. Preferably, heat tape is used to heat outer shell tube  12 , which in turn heats both chlorine gas and inert gas flowing through outer tube  12  and the gaseous ammonia flowing through inner tube  16 .  
         [0036]    In the case of chloramine gas formation, outer shell tube  12  and inner tube  16  discharge into reaction chamber  18 . The chlorine gas reacts with the ammonia gas at reaction zone  20  in reaction chamber  18 . Reaction chamber  18  is heated to a temperature in excess of about 350° C. by one or more heating elements  22  and measured by one or more temperature sensors associated with heating elements  22 . It is critical to the invention that the reaction occur at a temperature in excess of about 350° C. to prevent the condensation and precipitation of ammonium chloride, a by-product of the gas-phase reaction occurring in reaction chamber  18 .  
         [0037]    A device or element for heating reaction zone  20  include, for example, heat tape, high resistivity wire, steam, furnace, and any combinations thereof. Preferably, heat tape is used.  
         [0038]    The product gas stream exits reaction chamber  18  via discharge tube  26  at a temperature still in excess of about 350° C.  
         [0039]    Referring to FIG. 2, the product gas stream, via discharge tube  26 , enters a solids collection system according to the present invention, represented generally by reference numeral  30 . Solids collection system  30  has a trap  32  with one or more baffles  34 ,  36 . Baffles  34 ,  36  help collect solids that may have precipitated out of the product gas. Following trap  32 , solids collection system  30  has one or more filters  38 ,  40 . Filters  38 ,  40  further collect any precipitated solids that may be in the product gas. The product gas discharges from solids collection system  30  via discharge line  42 .  
         [0040]    Any suitable filters, compatible with the desired product gas, may be used with solids collection system  30 . Suitable filters for use in solids collection system  30  of the present invention include, but are not limited to, one or more cartridge filters, bag filters, granular bed filters, or any combinations thereof. Preferably, one or more cartridge filters are used. In a preferred embodiment of the present invention, one or more cartridge filters sold under the tradenames CT-101A® and Micro-Klean III® by CUNO may be used.  
         [0041]    Referring to FIG. 3, another embodiment of a reactor according to the present invention is represented generally by reference numeral  50 . Reactor  50  has the same attributes as those described with respect to reactor  10  set forth above, however, reactor  50  has discharge tube  26  that feeds product gas to at least two solid collection system feed tubes  52 ,  54 .  
         [0042]    Referring to FIG. 4, a solids collection system for use with the reactor depicted in FIG. 3 is represented generally by reference numeral  60 . Solids collection system  60  has the same attributes as those set forth above for solids collection system  30  depicted in FIG. 2, however, system  60  has two collection units  62 ,  64 .  
         [0043]    Collection unit  62  receives product gas via collection system feed tube  52 . Collection unit  64  receives product gas via collection system feed tube  54 . Both collection units  62 ,  64  remove solids from the product gas by the same mechanisms described above for collection system  30  depicted in FIG. 2.  
         [0044]    A benefit of having more than one solids collection system according to the present invention is that it provides an end user of the reactor with various operating configurations to optimize the continuous production of the desired product gas. For example, the reactor with two or more collection system tubes, and corresponding collection systems, can be operated simultaneously on a continuous basis.  
         [0045]    In another embodiment, the reactor with two or more collection system tubes and corresponding solids collection systems can be run in parallel, but not simultaneously. Therefore, when one or more collection systems require maintenance, those collection systems can be taken off-line, while one or more remaining collection systems either remain on-line or are put into service to replace the systems taken off-line. As a result, the continuous process never requires down time due to maintenance of the two or more solids collection systems.  
         [0046]    It should be understood that while FIG. 3 depicts a reactor with two collection system feed tubes and FIG. 4 depicts two associated solid collection systems, one skilled in the art would appreciate that the present invention can be configured with any number of collection system feed tubes and associated solids collection systems to ensure continuous operation and production of product gas.  
         [0047]    Referring to FIG. 5, another embodiment of a solids collection system according to the present invention is represented generally by reference numeral  70 . Solids collection system  70  has cyclone  72 , to which product gas is fed via reactor discharge tube  26 . Cyclone  72  is effective at removing any solids that may have precipitated out of the product gas. Any solids removed by cyclone  72  will collect in collection drum  76 . Product gas exits cyclone  72  via cyclone discharge line  78 , which in turn feeds filter  80 . Filter  80  further collects any remaining solids that may have precipitated out of the product gas. The product gas discharges from filter  80  via filter discharge line  82 .  
         [0048]    It should be understood that while FIG. 5 depicts a reactor with one solids collection system, one skilled in the art would appreciate that the present invention can be configured with any number of collection systems, similar to those set forth above with respect to FIGS. 3 and 4, to ensure continuous operation and production of product gas. In addition, any combination of the solids collection systems depicted in FIGS. 2, 4 and  5  may be configured, as will be appreciated by one skilled in the art.  
         [0049]    The present invention is further illustrated by the following example.  
       EXAMPLE 1  
       [0050]    Cl 2  was diluted in 12 parts of N 2 . Ammonia gas was charged at a stoichiometric amount with a slight excess. The first run flowed 0.125 L/min Cl 2  mixed with 1.5 L/min N 2 , which was reacted with 0.3 L/min NH 3 . The two gases were reacted at temperatures between 350° C. to 400+° C. The total reaction time to convert 10 kilos was 170 hours. The throughput was then increased four times by increasing the flow rates by four times. However, the N 2  ratio was decreased three times to 2 L/min in order to increase the overall throughput while minimizing the increase in the overall flowrate.  
         [0051]    In order to monitor the progress of the reaction, a GC/MS was placed in-line with the reaction. By splitting the stream exiting the second filter, one of the streams was sent directly into the GC/MS. This apparatus was able to quantify the ratio between the amounts of chloramine, ammonia, and chlorine exiting the reactor by comparing the size of the peaks of elements with certain molecular weights. A sample of this data can be seen in FIG. 6.  
         [0052]    It can be seen from FIG. 6 that the stream consists almost entirely of chloramine at a ratio greater than 10:1 with respect to ammonia. Ammonia is expected because there is a slight excess being fed into the reactor. It can also be seen that chlorine does not appear because it is almost entirely consumed in the reaction.  
         [0053]    It is to be understood that what has been described is merely illustrative of the principles of the invention and that numerous arrangements in accordance with this invention may be devised by one skilled in the art without departing from the spirit and scope thereof.