Reactor for a carbochlorination process with a double-wall inlet tube and method

Abstract

A reactor has a double-wall inlet tube for supplying a gas that contains a chlorination agent and also providing a protective gas shrouding at the end of the inlet tube. The reactor includes a reactor vessel with a protective lining on the inside wall. The double-walled inlet tube extends into the reactor vessel through the protective lining. The double-walled chlorine inlet tube has an inner pipe, an outer pipe, and a peripheral space between the inner and outer pipes. The chlorination agent containing gas is injected into the reactor vessel through the inner pipe, and the protective gas is injected simultaneously into the reactor vessel through the outer pipe in the peripheral space between the inner pipe and the outer pipe to form a protective gas shroud around the end of the double-wall inlet tube. The protective gas may be recycled from other portions of the process to reuse various materials produced from carbochlorination process.

Description

REACTOR FOR A CARBOCHLORINATION PROCESS WITH A DOUBLE-WALL INLET TUBE AND METHODFIELD OF THE INVENTION

[0001] The present invention relates generally to a reactor for a carbochlorination process with a double-wall inlet tube, a method of injecting a chlorination agent containing gas into a reactor vessel, such as a fluidized bed reactor, and a plant process configuration including the reactor.BACKGROUND

[0002] Titanium dioxide (TiO2) has many known commercial uses, including use as a pigment for many different materials. TiO2 is manufactured in various multi-step processes from a titanium feedstock. One such process is the chloride process. The chloride process typically begins with the formation of titanium tetrachloride (TiCL4) by mixing raw titanium containing feedstock materials with gaseous chlorine at a temperature of around 900°C - 1000°C in a fluidized bed reactor in the presence of coke or other appropriate carbonaceous material as a reducing agent in an exothermic reaction. The resulting gas stream emitted from the fluidized bed and exhausted from the fluidized bed reactor contains TiCI4 (as well as other by-products), which is subsequently processed into TiO2 particles by other processing steps.

[0003] The current technology for the introduction of the chlorine gas or any other type of chlorination agent(s) into the fluidized bed during the carbochlorination reaction process uses a singlewalled inlet tube that extends through the lining, usually a brick-lining, covering the inner surface of the reactor mantle, including sidewalls, the reactor bottom and sometimes the reactor top. However, the inlet tubes corrode away chemically and erode both mechanically and thermally over time due to their constant contact with the chlorine gas or other chlorination agents and / or abrasives contained in corrosive fluidized bed during the carbochlorination reaction process, as well as due to being exposed to alternating thermal stress during start-ups and / or shut-downs of the operation. Unfortunately, the inlet tubes and / or protective lining adjacent to the inlet tubes need to be replaced and / or repaired relatively frequently because of the erosion and the corrosion processes, which adds expense and downtime for the manufacture of TiO2.

[0004] Therefore, it would be desirable to have a system, apparatus, and / or method that would, while the carbochlorination process is running inside the fluidized bed reactor vessel, lengthen the useful life of the inlet tubes into the fluidized bed reactor and / or the protective lining adjacent to theinlet tubes and thereby reduce maintenance costs and / or downtime of the fluidized bed reactor.SUMMARY OF THE INVENTION

[0005] According to some non-limiting aspects of the invention, the present invention provides a reactor, a method of injecting a chlorination agent containing gas into a reactor vessel that can reduce mechanical erosion, thermal erosion, and / or chemical corrosion of the inlet pipes into the reactor vessel and / or the protective lining adjacent to the inlet, and a plant process configuration including the reactor.

[0006] In one non-limiting aspect of the invention, a reactor for a carbochlorination process is provided. The reactor may include a reactor vessel with an inside wall, a protective lining on the inside wall, and a double-walled inlet tube for the chlorination agent containing gas extending into the reactor vessel through the protective lining. The double-walled inlet tube may include an inner pipe, an outer pipe surrounding the inner pipe, and a peripheral space between the inner pipe and the outer pipe. The chlorination agent containing gas can be introduced into the reactor vessel through an end of the inner pipe. A protective gas can be introduced into the reactor vessel through an end of the outer pipe in the peripheral space between the inner pipe and the outer pipe. In some non-limiting embodiments, the reactor includes two or more of the double-walled inlet tubes extending into the reactor vessel.

[0007] In another non-limiting aspect of the invention, a method of injecting a chlorination agent containing gas into a reactor vessel having a double-walled inlet tube for the carbochlorination process of forming titanium tetrachloride from titanium feedstock using carbonaceous material as a reducing agent is provided. The method may include injecting the chlorination agent containing gas into the reactor vessel through an end of an inner pipe of the double-walled inlet tube. A protective gas may be simultaneously injected into the reactor vessel through a peripheral space between the inner pipe and an end of an outer pipe of the double-walled inlet tube. In some arrangements, the protective gas may form a protective gas envelope (e.g., cloud, cushion, mantle, and / or shroud) around the end of the inner pipe, and preferably also around the end of the outer pipe. The protective cloud can thereby protect the ends of the inner and / or outer pipe from chemical erosion and / or physical erosion from the particles and chloride process reactions occurring inside the reactor vessel.

[0008] In a further non-limiting aspect of the invention, a plant process configuration for forming titanium tetrachloride from titanium feedstock using a carbochlorination process using carbonaceous material as a reducing agent is provided. The plant process configuration includes a reactor as described above.

[0009] The reactor may be any type of reactor configured for containing a carbochlorination reaction and where the doble-walled pipes can be used as an introduction system for chlorination agents. In some non-limiting embodiments, the reactor may be a fluidized bed reactor, a circulating fluidized bed reactor, a bubbling bed reactor, a spouted bed reactor, slugging bed reactor, a riser type reactor, a vertical shaft (furnace type) reactor, a moving bed reactor, a cyclone reactor, or a reactor having various features from more than one of these types of reactors.

[0010] In some optional configurations, the chlorination agent containing gas may carry and / or include chlorine as a chlorination agent for driving the carbochlorination process. In some arrangements, the chlorination agent containing gas may include other chlorination agents for driving the carbochlorination process, such as phosgene (COCI2), carbon tetrachloride (CCI4), thionyl chloride (SOCI2), sulfuryl chloride (SO2CI2), and / or mixtures thereof.

[0011] In some optional configurations, the end of the outer pipe may be flush with an inner surface of the protective lining or extend beyond an inner surface of the protective lining into the reactor vessel. The end of the inner pipe may be flush with the end of the outer pipe, may extend beyond the end of the outer pipe into the reactor vessel, or may be recessed within the end of the outer pipe. The outer pipe can thereby also mechanically protect at least portions of the inner pipe by shielding the inner pipe from being hit by abrasive particles and / or larger objects inside the reactor vessel during the carbochlorination process.

[0012] In some optional configurations, the peripheral space may extend around the entire outer periphery of the end of the inner pipe. This arrangement may ensure or promote the formation of a protective cloud of the protective gas around and / or enveloping the entire periphery of the exposed end of the inner pipe. It may also promote the formation of a protective cloud of the protective gas around the entire periphery of the end of the outer pipe. The peripheral space may be a circumferential or annular shape or have other shapes that extend around the outer peripheral surface of the outer pipe in the space between the inner pipe and the outer pipe, depending on the cross-sectional shapes of the pipes and / or the orientation of the pipes relative to each other. In some optional configurations, the peripheral space may be interrupted by ribs, standoffs, posts, partial end walls, or other types of supports and / or spacers between the outer periphery of the inner pipe and the inner periphery of the outer pipe to maintain the peripheral space between the two pipes.

[0013] In some optional configurations, the reactor may include other features. In some non-limiting examples, a titanium feedstock inlet tube may extend into the reactor vessel for injecting titanium feedstock into the reactor vessel, a carbon feedstock inlet tube may extend into the reactor vessel for injecting a carbon feedstock into the reactor vessel, and / or an exhaust opening may be disposed at atop end of the reactor vessel for exhausting a gas stream containing titanium tetrachloride from inside the reactor. Optionally, the titanium feedstock inlet tube and / or the carbon feedstock inlet tube may be double-walled tubes similar to the double-walled inlet tube for the chlorination agent containing gas. Optionally, one or more additional double-walled inlet tubes as described above may extend into the reactor to provide additional feeds of the chlorination agent containing gas into the reactor. Any one or more of the titanium feedstock inlet tubes, the carbon feedstock inlet tube, and the doublewalled inlet tube(s) may extend into the reactor near a bottom end of the reactor vessel, for example through a conical bottom wall of the reactor vessel, to allow and / or promote upward flow of the chlorination agents and gases that evolve during the carbochlorination reaction to form a in the lower portion of the reactor vessel.

[0014] In some optional configurations, the protective lining may include heat resistant refractory material. The protective lining is selected to protect inner surface of the reactor vessel mantle, or other inner wall surrounding the carbochlorination reaction area inside the reactor, from damaging effects of heat and / or chemical reactions that occur during the carbochlorination process. For example, the protective lining may include and / or may be formed of refractory bricks lining the inside wall of the reactor vessel. However, other types and / or forms of refractory materials, such as a monolithic refractory lining, and / or cast refractory materials, may be used to form the protective lining along the inside surface of the inside wall of the reactor vessel mantle to protect the reactor vessel mantle. The protective lining may include non-refractory materials.

[0015] In some optional configurations, the chlorination agent containing gas is injected into the reactor vessel through the inner pipe at a first velocity, and the protective gas is injected into the reactor vessel at a second velocity through the peripheral space between the inner pipe and the outer pipe, wherein the second velocity is equal to or greater than the first velocity. This may cause the protective gas to create a protective gas envelope around the ends of inlet tubes and / or push the abrasive bed of the fluidized bed away from the pipes of the double-walled inlet pipe, and possibly also the adjacent lining.

[0016] In some optional configurations, the chlorination agent containing gas may be injected at a first temperature and the protective gas may be injected at a second temperature. Preferably, the second temperature is lower than the first temperature, which may help reduce the corrosion rate by lowering the temperature of the inner tube and the outer tube.

[0017] In some optional configurations, the protective gas may include one or more inert gases, such as carbon monoxide (CO), carbon dioxide (CO2), nitrogen gas (N2), and / or another inert gas, and mixtures thereof. The inert gases may provide a protective gas envelope (e.g., cloud, shroud) aroundthe chlorination agent containing gas immediately adjacent the end of the double-walled inlet pipe so that the reaction with the bed material during the carbochlorination process does not take place directly at the mouth of the pipe and at the lining, but rather at a distance from the mouth / outlet of the pipe and in the bulk of the fluidized bed.

[0018] In some optional configurations, the protective gas may include one or more reactive gases, such as titanium tetrachloride (TiCI4), chlorine gas (CI2), carbon tetrachloride (CCI4), and / or other reactive gas (e.g., COCI2, CO, etc.), and mixtures thereof. TiCI4 and / or CI2 may be particularly suitable as protective gases because they can originate from the carbochlorination process and are recirculated within the plant, thereby providing for improved efficiency and / or environmental characteristics of the carbochlorination process. When a reactive gas is used as a protective gas, the temperature of the reactive gas(es) are preferably at least about 100 °C cooler than the chlorination agent containing gas flowing through the inner pipe. Preferably, the temperature of the reactive gas(es) is also above the condensation temperature point of the protective gas and / or the chlorination agent containing gas. This may prevent the gases from condensing and / or liquifying inside the pipe(s), which could cause unwanted chemical erosion and / or undesirable accumulation of liquid, for example, by wetting of the surfaces of the pipes and / or the surface of the protective lining.

[0019] In some optional configurations, the protective gas and / or protective agent for the protective gas may be at least partly recycled from another plant process including the carbochlorination process, may be supplied from a fresh source, and / or may be supplied from a combination of recycled and fresh sources. For example, the protective gas may include recycled off-gas from the carbochlorination process, and the protective agent preferably includes CO2, CO, and / or mixtures thereof. The protective gas may optionally include recycled chlorination agent from the carbochlorination process, and preferably includes CI2, TiCI4, COCI2, and / or mixtures thereof. The plant process configuration may optionally include a supply of recycled protective gases from other processes in the plant process configuration and / or a supply of fresh protective gases for supplying to the double-walled inlet tube. For example, the supply of recycled protective gases optionally may include at least one of recycled off-gas, recycled chlorination agent, and mixtures thereof. Optionally, the recycled protective gases may be supplied from one or more process apparatuses of the carbochlorination process including, for example, an off-gas treatment apparatus, a gas phase transformation apparatus, a solid phase transformation apparatus, and / or combinations thereof.

[0020] In some configurations and / or embodiments, the reactor and / or method and / or plant process configuration of the present invention may provide apparatus and systems that extend the usable life of one or more of the inlet pipes for injecting materials into a fluidized bed reactor, such as for the carbochlorination process of titanium feedstock, and thereby reduce maintenance costs and / orinactive time (e.g., downtime) of the reactor.

[0021] These, and other aspects, configurations, advantages, uses, and / or characteristics of the invention will become apparent upon review of the following detailed description and the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic vertical cross-sectional view of a fluidized bed reactor according to certain non-limiting aspects of the invention;

[0023] FIG. 2 is an enlarged schematic axial cross-sectional view of the end of a double-walled inlet pipe in the circled portion of FIG. 1;

[0024] FIG. 3 is a schematic end view of the double-walled inlet pipe;

[0025] FIG. 4 is a schematic process diagram representing an example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor of FIG. 1;

[0026] FIG. 5 is a schematic process diagram representing another example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor;

[0027] FIG. 6 is a schematic process diagram representing yet another example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor;

[0028] FIG. 7 is a schematic process diagram representing still another example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor;

[0029] FIG. 8 is a schematic process diagram representing a further example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor;

[0030] FIG. 9 is a schematic process diagram representing a still further example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor; and

[0031] FIG. 10 is a schematic process diagram representing yet a further example plant process arrangement for supplying a protective gas to the double-walled inlet pipe and fluidized bed reactor.DETAILED DESCRIPTION OF THE DRAWINGS

[0032] The following description is meant to describe what is shown in the drawings and / or various contemplated embodiments shown and / or related to what is shown in the drawings. Theembodiment(s) shown in the drawings are non-limiting examples and do not themselves define the invention. Any of the features shown and / or described in relation to one embodiment may be combined with any one or more features shown and / or described relative to another embodiment. Any dimensions shown in the drawings are exemplary only and are not intended to limit the scope of the invention. The term "a" is used herein as an open, inclusive term to include one or more than one item described thereby and is not limited to only one such item described thereby.

[0033] Turning nowto FIGS. 1-3, a reactor 10 according to one non-limiting embodiment is configured for running and containing the carbochlorination process of titanium feedstock, in which a chlorination agent containing gas is combined with a titanium feedstock and a carbonaceous material under high heat to form titanium tetrachloride, in a manner well understood in the art. The titanium feedstock may include, for example, rutile, synthetic rutile, high-grade ilmenite, titanium containing slag, or any other titanium containing feedstock material suitable for processing in a fluidized bed during the carbochlorination process to generate TiCI4 and / or other desirable reaction products. As explained in further detail hereinafter, the reactor 10 has one or more double-wall inlet tubes for introducing one or more chlorination agents into the fluidized bed reactor while providing a capability for a protective gas shrouding at the end of the double-walled inlet tube.

[0034] While the drawings relate to the non-limiting example reactor 10 shown in the drawings as used for running a carbochlorination process using a fluidized bed (typically called a "fluidized bed reactor") to obtain TiCI4 from a titanium feedstock, a chlorination agent, a carbonaceous material, in an exothermic reaction, the invention is not necessarily limited only to a fluidized bed reactor. Rather, the invention may be used in other types of reactors where carbochlorination reaction can be conducted and where the double-walled pipes can be used as an introduction system for chlorination agents and / or other materials, such as a circulating fluidized bed reactor, a bubbling bed reactor, a spouted bed reactor, slugging bed reactor, a riser type reactor, a vertical shaft (furnace type) reactor, a moving bed reactor, and / or a cyclone reactor. Further, the invention is not limited to a reactor vessel having the exact geometries of the example reactor in the drawings. Rather, a reactor of the invention can have various different geometries, such as conical, cylindrical, or rectangular, with or without internals, and / or with or without a constant diameter. Additional details of some but not necessarily all types and geometries of reactors that are suitable for containing the carbochlorination process are disclosed in "Spouted and Spout-Fluid Beds Fundamentals and Applications" by Norman Epstein, John R. Grace (Cambridge University Press, 2011), the contents of which are incorporated herein by reference in their entirety.

[0035] The reactor 10 includes a reactor vessel 12 having an outer mantle 14 that forms a sidewall extending between an upper wall and a lower wall and defining an enclosed reaction space therein.In this example, the reactor vessel 12 is a cone-bottom vessel with the sidewall having a generally cylindrical shape, the bottom wall having an inverted cone shape, and the top wall having generally convex upwardly dome shape; however, other shapes and forms of the reactor vessel 12 are possible. The outer mantle 14 may be formed of a suitable material, such as steel, stainless steel, or other suitably strong material. A protective lining 16 is disposed along the radially inner surface of an inside wall 18 of the mantle 14 to protect the inside wall from abrasion and / or corrosion from heat and / or chemicals inside the reactor vessel 12 during the carbochlorination process. The protective lining 16 preferably covers the entire inner surface of the inside sidewall 18 and bottom wall of the outer mantle and may also cover all or portions of the inner surface of the upper wall, depending on the type of protective lining used. The protective lining 16 is preferably made of a heat resistant, and optionally chemically resistant, material, such as a refractory material. In this example, the protective lining 16 is formed of bricks lining the inner wall surface of the outer mantle, however other types of refractory or protective materials, such as monolithic and / or cast materials may be used. During use, a fluidized bed 20 is formed in the lower end of the reactor vessel 12, where titanium feedstock, carbonaceous material (e.g., coke particles), and a chlorination agent are mixed by one or more streams of chlorination agent containing gases, protective gases, process supporting gases (e.g., air), and gases evolved by the carbochlorination reaction with the titanium containing materials and carbonaceous materials flowing upwardly and thermally expanding from the bottom of the reactor participating in the carbochlorination reaction under exothermic conditions that forms the TiCI4 and other byproducts. The chlorination agent may include one or more of chlorine, phosgene (COCI2), carbon tetrachloride (CCI4), thionyl chloride (SOCI2), sulfuryl chloride (SO2CI2), and / or mixtures thereof. Other chlorination agents suitable for driving the carbochlorination reaction may be used. The solids and gases may be introduced (e.g., injected) into the reactor vessel in any suitable spatial relationship to each other capable of forming and / or maintaining a functioning fluidized bed, for example with the gases entering from the bottom and solids from above and / or with at least a fraction of solids introduced though separate piping from the bottom.

[0036] A double-walled inlet tube 22 extends into the reactor vessel 12, for example through the outer mantle 14 and the protective lining 16, for supplying a flow of a chlorination agent containing gas into the interior of the reactor vessel to help drive the carbochlorination reaction in the fluidized bed 20. The end of the double-walled inlet tube 22 preferably is disposed in the lower portion of the reactor vessel 12, such as in or near the bottom cone of the vessel as shown in FIGS. 2 and 3, to introduce the chlorination agent directly into the fluidized bed 20, for example by injecting the chlorination agent containing gas. The double-walled inlet tube 22 has an inner pipe 24 and an outer pipe 26 surrounding the inner pipe, wherein the inner pipe 24 is disposed inside the interior bore ofthe outer pipe and extends axially along the length (longitudinal axis) of the outer pipe. Preferably, the inner pipe 24 is approximately or substantially coaxial with the outer pipe 26. A peripheral space 28 (e.g., a circumferential or annular space) is defined between the outer surface of the inner pipe 24 and the inner surface of the outer pipe 26. Preferably, the inner pipe 24 and outer pipe 26 are coaxially aligned such that the peripheral space 28 preferably has a constant distance S between the inner pipe and the outer pipe around the entire periphery of the two pipes and along the length of the doublewalled inlet tube. In use, a gas that contains a chlorination agent is supplied into the reactor vessel 12 through the inner pipe 24, and at the same time a protective gas is supplied into the reactor vessel through the peripheral space 28 between the inner pipe and the outer pipe. Thus, the chlorination agent containing gas is injected through the end 30 of the inner pipe directly into the fluidized bed area 20, and the protective gas is injected through the end 32 of the outer pipe in the peripheral space 28 surrounding the inner pipe. Although it is typical for the each of the inner and outer pipes 24 and 26 to have a generally circular cross-sectional shape, the inner and / or outer pipes may have other cross-sectional shapes, such as oval, polygonal, rectangular, etc., and the term "peripheral" is not limited to only a circular peripheral shape, but may include any shape that extends around the outer periphery of the inner pipe between the outer periphery of the inner pipe and the inner periphery of the outer pipe.

[0037] As shown in the drawings, the end 32 of the outer pipe 26 is flush with an inner surface of the protective lining 16. In this arrangement, the protective lining 16 can protect the outer surface of the outer pipe 26 from mechanical and / or chemical wear. In some arrangements, the end 32 of the outer pipe 26 may extend beyond the inner surface of the protective lining 16 into the reactor vessel 12. The end 30 of the inner pipe 24 may be disposed flush with the end 32 of the outer pipe 26, as shown in the drawings. However, in other arrangements, the end 30 of the inner pipe 24 may extend into the reaction space slightly beyond the end 32 of the outer pipe, or the end 30 of the inner pipe 24 may be recessed back from the end 32 of the outer pipe into the outer pipe. In any of the configurations, the peripheral space 28 preferably extends around the entire outer periphery of the inner pipe near its end 30 to ensure that the protective gas envelops the entire periphery of at least the end 30 of the inner pipe 24, and preferably ends 30 and 32 of both the inner piper 24 and the outer pipe 26. However, some breaks in the peripheral space 28 may be formed, for example, by one or more ribs, posts, end wall portions, standoffs, or other types of spacers, to maintain the inner and outer pipes apart to form the peripheral space 28. In any event, such spacers do not completely close off the peripheral space 28 at the end 32 of the outer pipe 26 so that the protective gas can flow through the end around the end 32 of the inner pipe 26.

[0038] Preferably, the velocity Vo of the protective gas flowing through the end 32 of the outer pipe26 is at least equal to, and more preferably greater than, the velocity Vi of the chlorination agent containing gas flowing through the end 30 of the inner pipe 24. By conveying (e.g., by pumping) the protective gas at higher velocity Vo than the velocity Vi of the chlorination agent containing gas, the protective gas can form a protective gas envelope around the end of the double-walled tube 22 that pushes the abrasive fluidized bed materials away from the inner and outer pipes 24 and 26 and areas of the protective lining 16 immediately adjacent to the end of the double-walled inlet tube. In this way, the protective gas also prevents the chlorination agent containing gas from locally wetting the piping 24 and 25 and adjacent surfaces of the protective lining 16, thereby preventing the chlorination agent from chemically corroding the end 30 of at least the inner pipe 24 and also typically at least partially protecting the end 32 of the outer pipe 26. As used herein, the term wetting means a surface phenomenon where chlorination agent containing gas does not form a bubble that leaves the pipe directly into the fluidized bed, but instead spreads around the pipe outlet onto the surface of the lining (and of the pipe) forming an intimate contact with it (or them), and then being so close to the surface that it causes unwanted corrosion by reaction when appropriate temperature is reached by the exothermic process. The outer pipe 26 is also protected from mechanical abrasions by the surrounding protective lining 16. Thus, both the flow of protective gas and the reactor lining act to protect the outer pipe 26 from mechanical and chemical wear.

[0039] The reactor 10 may include additional features for carrying out the carbochlorination process. For example, a titanium feedstock inlet tube 34 may be provided for supplying titanium containing feedstock into the reactor vessel 12. A carbonaceous material inlet tube 36 may be provided for supplying a carbonaceous material, such as coke particles, into the reactor vessel 12. Typically, the main fraction of solid materials (e.g., carbonaceous material and titanium feedstock) is introduced into the reactor interior though one or more openings disposed above the level of the fluidized bed 20. In the non-limiting example shown in FIG. 1, the inlet pipes 34 and 36 extend into the interior of the reactor vessel 12 through the sidewall to introduce the titanium feedstock and carbonaceous material above the level of the fluidized bed 20. However, in other configurations, the inlet pipes may be located in other areas of the reactor vessel, such as through the top wall of the vessel and / or below the operating level of the fluidized bed 20 disposed through the side wall of the outer mantel and / or through the bottom wall of the outer mantel. In this example, each of the titanium feedstock inlet tube 34 and the carbonaceous material inlet tube 36 are shown as being single walled tubes. However, in some configurations, one or more of the titanium feedstock inlet tube 34 and the carbonaceous material inlet tube 36 may also be double-walled inlet pipes similar to the double-walled inlet tube 22 so that a protective gas may be conveyed through the outer pipe in the peripheral space to also protect the ends of each of these inlet tubes 34 and 36. An exhaust opening 38 may be provided toallow hot gases carrying TiCI4, particulate matter, and / or other materials from the fluidized bed area 20 to exhaust out of the reactor vessel 12 for capture and / or further processing. The exhaust opening is preferably disposed spaced above the top level of the fluidized bed 20. In this example, the exhaust opening 38 is disposed in the top wall of the outer mantle, however, it could be located in other areas of the reactor vessel.

[0040] In use during a carbochlorination process, the chlorination agent containing gas is injected into the reactor vessel 12 through the inner end 30 of the inner pipe 24, and at the same time a protective gas is injected into the reactor vessel through the peripheral space 28 between the inner pipe 24 and the inner end 32 of the outer pipe 26. The protective gas is preferably conveyed (e.g., pumped) at a higher velocity Vo than the velocity Vi of the chlorination agent containing gas, so that the protective gas creates a protective gas envelope around the ends 30 and 32 of inlet tubes 24 and 26 and pushes the abrasive material in the fluidized bed away from the pipes and adjacent lining. The flow of protective gas also prevents the chlorination agent containing gas from locally wetting the piping and adjacent lining surfaces, thereby preventing the chlorination agent from chemically corroding the end of one or both of the inner pipe 24 and outer pipe 26 or the adjacent area of the protective lining 16. The protective gas preferably is conveyed along the peripheral space 28 at a lower temperature than the chlorination agent containing gas inside the inner pipe 24 in order to lower the temperature of the inner pipe 24 and reduce the corrosion rate. Although the method of injecting the chlorination agent containing gas is described herein with reference to the reactor 10 illustrated in the drawings, the method could be used with fluidized bed reactors having different arrangements and / or features and is not limited to use with only the reactor 10 illustrated in the drawings.

[0041] The protective gases may be any inert gas or mixture of gases that will not impede the carbochlorination reaction and help protect the pipes 24 and 26. The term inert as used herein refers to material and / or gases do not participate in the primary carbochlorination reaction in the reactor 10. For example, the protective gas may be or include any one or more of carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), and mixtures thereof. The inert gases provide a protective gas envelope around the chlorination agent containing gas so that the reaction with the material in the fluidized bed does not take place directly at the mouth of the double-walled pipe 22 and at the lining, but rather at a distance into the fluidized bed. This can thereby prevent wetting of the protective lining 16 with chlorine. CO and CO2 are particularly suitable as inert gases because they can be recirculated from various processes within the manufacturing plant. In times of operation when recirculation is not available, N2 may be used instead. While such inert protective gases may be introduced at any desired suitable temperature, it is preferred that they are injected at a cooler temperature than the chlorination agent containing gas.

[0042] In some arrangements, the protective gas(es) may be or include one or more reactive gases. For example, the protective gas may include reactive gasses such as of titanium tetrachloride (TiCI4), chlorine gas (CI2), carbon tetrachloride (CCI4), carbon monoxide (CO), phosgene (COCI2), and / or mixtures thereof. Pure TiCI4 and CI2 may be particularly suitable as protective gases because they originate from the chloride process for forming TiO2 and may be recirculated from various processes within the manufacturing plant. The temperature of the reactive gases when used as the protective gases are preferably at least 100 °C cooler than the chlorination agent containing gas flowing through the inner pipe 24. However, the temperature of the reactive gases when used as the protective gases is preferably also above their own condensation point(s). For example, if pure TiCI4 is used, it is preferably in gaseous form and has a temperature of at least 140 °C before entering the outer pipe 26. In another example, if CI2 is used, it is preferably gaseous, particle-free, and has a temperature of at least -30 °C before entering the outer tube. If phosgene is used as the protective gas, its temperature is preferably at least +9°C or greater before entering the outer tube.

[0043] The following section provides some nonlimiting example dimensions, volumetric ratios, velocities, and other data that may be used for the reactor 10; however, it is understood that these data are by way of example only for some preferred configurations and are not meant as limitations. The inner pipe 24 may have an inner diameter (di) between about 20 mm and about 200 mm, preferably between about 60 mm and about 160 mm, and more preferably between about 100 mm and about 140 mm, and a wall thickness (tj) between about 4 mm and about 12 mm, preferably between about 6 mm and about 8 mm. The distance between the inner pipe 24 and the outer pipe 26 corresponding to the width (S) of the peripheral space 28 may be between about 1 mm and about 6 mm, preferably between about 2 mm and about 3 mm. The wall thickness (t0) of the outer pipe 26 may be between about 6 mm and about 15 mm, preferably between about 8 mm and about 12 mm. The relative height (proud distance) of the inner pipe 24 to the protective lining 16 may be between about 0 mm (i.e., flush with the lining) and about 50 mm extending proud of the protective lining, and the end of the outer pipe 26 is about flush with the end of the inner pipe 24. The injection velocity (Vi) of the gases in the inner pipe 24 may be between about 1 m / s and about 50 m / s, preferably between about 5 m / s and about 25 m / s, and may depend on the position of the single-discharge tube and its hydrostatic height. The injection velocity (Vo) of the gases in the outer pipe 26 (in the peripheral space 28) is preferably but not necessarily at least the same as, and more preferably faster than the velocity (Vi). For example, the ratio of Vi to Vo(Vi:V0) may be between about 2:1 and about 1:2, preferably between about 1:1 and about 1:2, and more preferably between about 1:1.1 to about 1:1.6. The ratios of the volumetric flows between the inner pipe and the outer pipe (Vi:V0) may be between about 100:50 and about 100:1, preferably between about 100:20 and about 100:5. The ratio of thevolumetric flows may depend on the geometry of the pipe system. The reactive refrigerant and conductive gases introduced through the outer pipe 26 (in the peripheral space 28) may include one or more of at least TiCI4, 02, CCI4, and mixtures thereof. The inert cooling and conductive gases in the outer pipe 26 may include one or more of at least C02, CO, N2 , and mixtures thereof. The temperature for reactive gases flowing through the outer pipe 26 may be above their condensation point and may be at least about 100 °C cooler than the temperature of the gases flowing through the inner pipe 24. The temperature for inert gases flowing through the outer pipe 26 may be below the temperature of the reverse chlorine, and otherwise may be freely selectable within the appropriate ranges. The inclination of the double-walled tube 22 may be between about vertical and about horizontal, and preferably within about 30° of horizontal, more preferably within about 15° of horizontal, and even more preferably about horizontal. The bevel of the ends of the inner and outer pipes 24 and 26 may be perpendicular to the axis of the respective pipes, but can be other angles, for example adapted to any slope of the outer surface of the protective lining 16 if appropriate. Other dimensions, velocities, temperatures, ratios, angles, etc., may be used if desired in other configurations and embodiments of the reactor 10.

[0044] FIGS. 4-10 show several nonlimiting examples of plant process configurations that are adapted to supply one or more protective gases to the double-walled inlet pipe 22 for injecting a chlorination agent and a protective cloud of the protective gases as described previously. As mentioned previously herein, the protective gas(es) may include one or more inert gases and / or reactive gases. These protective gases may be provided from fresh sources and / or may be provided from recycled gases from the carbochlorination process. Similarly, the chlorination agent may be supplied from a fresh source and / or recycled from the carbochlorination process.

[0045] FIG. 4 schematically illustrates a nonlimiting example of a plant process configuration 100 in which an inert protective gas is provided from a fresh source to the double-walled inlet pipe(s) 22. A fresh / makeup supply of a protective agent is supplied to a protective agent tank 102. A protective gas including the protective agent is supplied from the protective agent tank 102 to the outer pipe 26 of the double-walled inlet pipe 22, from which the protective gas is injected into the reactor 10 as described previously. The protective agent in the fresh / make up supply is preferably carbon dioxide (CO2) and / or carbon monoxide (CO), although other protective agents are possible. Chlorination agent is provided to a chlorination agent tank 104, for example from a fresh / make up supply source of the chlorination agent. The chlorination agent containing gas is supplied from the chlorination agent tank 104 to the inner pipe 24 from which the chlorination agent containing gas is injected into the reactor 10 as described previously. One or more various post-reactor processes may optionally be provided as part of downstream processing of TiCI4 and / or other gases, product(s), and / or by-products of thecarbochlorination process that occurs inside the reactor 10. For example, solids and gases exhausted from the fluidized bed reactor 10 may be separated at a reactor discharge separation apparatus 106. Solid phase matter from the reactor discharge separation apparatus 106 may be treated at a solid phase treatment apparatus 108. Solid matter from the solid phase treatment apparatus 108 may be transformed at a solid phase transformation apparatus 110, from which by-products may be discharged for collection and / or further processing. Gaseous phase material from the reactor discharge separation apparatus 106 may be separated at a phase separation apparatus 112. Product containing portions from the gas phase separation apparatus 112 may be processed at a gas phase transformation apparatus 114, from which one or more final products may be obtained. Other offgases from the gas phase separation apparatus 112 may be treated at an off-gas treatment apparatus 116, from which one or more off-gases are exhausted.

[0046] FIG. 5 schematically illustrates a nonlimiting example of a plant process configuration 200 in which an inert protective gas is provided from both a fresh source and from a recycled source from the plant to the double-walled inlet pipe(s) 22. In this example, recycled off-gas is recycled for supplying as a protective gas to the double-walled inlet tube 22. Off-gas from the off-gas treatment apparatus 116 is directed back to the protective agent tank 102 for re-use as the protective agent. The protective agent in the recycled off-gas supply is preferably carbon dioxide (CO2) and / or carbon monoxide (CO), although other protective agents are possible. Fresh protective agent may also be provided to the protective agent tank as described previously. In some arrangements, the off-gas(es) may be obtained from other points in the processing after discharge from the reactor 10. The protective gas(es) and chlorination agent containing gas(es) are then supplied to the double-walled inlet tube 22 for injection into the reactor 10 as described previously. Remaining post-reactor processing may optionally be performed substantially as described previously at 106-116.

[0047] FIG. 6 schematically illustrates a nonlimiting example of a plant process configuration 300 in which a cooled reactive gas is provided to the double-walled inlet pipe(s) 22 for use as the protective gas as described previously rather than using a separate protective agent for the protective gas. In this nonlimiting example, a second flow of chlorination agent containing gas is directed from the chlorination agent tank 104 to a chlorination agent cooling apparatus 118 where the second stream of chlorination agent containing gas is cooled and then supplied for injection through the outer pipe 26 of the double-walled inlet tube(s) 22 as described previously. A primary stream of the chlorination agent containing gas is supplied from the chlorination agent tank to the inner pipe 24 as described previously herein. The protective gas(es) and chlorination agent containing gas(es) are then supplied to the double-walled inlet tube 22 for injection into the reactor 10 as described previously. Remaining post-reactor processing may optionally be performed substantially as described previously at 106-116.In this arrangement, a separate supply of protective gas(es) and protective agent tank 102 are not required.

[0048] FIG. 7 schematically illustrates another nonlimiting example of a plant process configuration 400 in which a cooled reactive gas is provided to the double-walled inlet pipe(s) 22 for use as the protective gas as described previously in which at least a portion of the protective gas is recycled gas(es) from the process for re-use as the protective gas. In this nonlimiting example, in addition to the fresh / make up supply of chlorination agent to the chlorination agent tank 104, a recycled supply of chlorination agent is conducted from the gas phase transformation apparatus 114 back to the chlorination agent tank 104 for recycling through the carbochlorination process. In this example, the recycled chlorination agent may include CI2, and / or TiCI4 and / or COCI2 and / or other matter emitted from the gas phase transformation apparatus 114. Remaining portions of process 104-118 are preferably performed substantially as described previously. In this arrangement, a separate supply of protective gas(es) and protective agent tank 102 are not required.

[0049] FIG. 8 schematically illustrates another nonlimiting example of a plant process configuration 500 in which a cooled reactive gas is provided to the double-walled inlet pipe(s) 22 for use as the protective gas as described previously in which at least a portion of the protective gas is recycled gas(es) from the process for re-use as the protective gas. In this nonlimiting example, in addition to the fresh supply of chlorination agent to the chlorination agent tank 104, a recycled supply of chlorination agent is conducted from the solid phase transformation apparatus 110 back to the chlorination agent tank 104 for recycling through the carbochlorination process. In this example, the recycled chlorination agent may include CI2, and / or TiCI4 and / or COCI2 and / or other matter emitted from the solid phase transformation apparatus 110. Remaining portions of process 104-118 are preferably performed substantially as described previously. In this arrangement, a separate supply of protective gas(es) and protective agent tank 102 are not required.

[0050] FIG. 9 schematically illustrates yet another nonlimiting example of a plant process configuration 600 in which a cooled reactive gas is provided to the double-walled inlet pipe(s) 22 for use as the protective gas as described previously in which at least a portion of the protective gas is recycled gas(es) from the process for re-use as the protective gas. In this nonlimiting example, in addition to the fresh / make up supply of chlorination agent to the chlorination agent tank 104, a recycled supply of chlorination agent is conducted from both the solid phase transformation apparatus 110 and the gas phase transformation apparatus 114 back to the chlorination agent tank 104 for recycling through the carbochlorination process. In this example, the recycled chlorination agent may include CI2, and / or TiCI4 and / or COCI2. Remaining portions of process 104-118 are preferably performed substantially as described previously. In this arrangement, a separate supply ofprotective gas(es) and protective agent tank 102 are not required.

[0051] FIG. 10 schematically illustrates a nonlimiting example of a plant process configuration 700 in which both an inert protective gas and a cooled reactive gas are provided to the double-walled inlet pipe(s) 22 for use as the protective gas as described previously in which at least a portion of the protective gas is recycled gases from the process for re-use as the protective gas. In this nonlimiting example, inert protective gas(es) is provided from the protective agent tank 102 to the outer pipe 26 of the double-walled inlet tube 22, and cooled chlorination agent containing gas(es) is also provided from the chlorination agent cooling apparatus 118 to the outer pipe 26 of the double-walled inlet tube 22, thereby supplying a mixture of inert and reactive protective gases for forming the protective envelope around the inner end of the double-walled inlet tube(es) 22 as described previously, in addition to the fresh supplies of protective gas and chlorination agent to the respective protective agent tank 102 and chlorination agent tank 104, a recycled supply of protective agent is conducted from the off-gas-treatment apparatus 116 to the protective agent tank 102, and a recycled supply of chlorination agent is conducted from both the solid phase transformation apparatus 110 and the gas phase transformation apparatus 114 back to the chlorination agent tank 104 for recycling through the carbochlorination process. In this example, the recycled chlorination agent may include CI2, and / or TiCI4 and / or COCI2, and the recycled protective agent may include CO and / or CO2. Remaining portions of process 104-118 are preferably performed substantially as described previously.

[0052] The plant process configurations in FIGS. 4-10 are provided to show a few nonlimiting examples of different possible ways of supplying fresh and / or recycled protective gas(es) to any one or more of the double-walled inlet tube(es) 22. It is understood however, that the invention is not necessarily limited to any one of the plant configurations, but rather may include any number of other configurations that allow for fresh and / or recycled inert and / or or reactive protective gases to the double-walled inlet tube(s) 22 for providing a protective shroud of gases at the inner end of the double-walled inlet tube(s) 22 inside the reactor 10 during operation of the carbochlorination process.

[0053] From these examples, it can be seen that a reactor, such as a fluidized bed reactor, and a method of injecting a chlorination agent containing gas into a reactor vessel of in accordance with one or more of the features described herein may provide an improved system, apparatus, and / or method for supplying a chlorination agent containing gas into the fluidized bed reactor that reduces mechanical and / or chemical wear and lengthens usable life if the inlet tube(s).

Claims

CLAIMS1. A reactor (10) for a carbochlorination process, the reactor comprising: a reactor vessel (12) with an inside wall (18); a protective lining (16) on the inside wall; a double-walled inlet tube (22) for the chlorination agent containing gas extending into the reactor vessel through the protective lining, the double-walled inlet tube comprising: an inner pipe (24); an outer pipe (26) surrounding the inner pipe; and a peripheral space (28) between the inner pipe and the outer pipe; wherein the chlorination agent containing gas can be introduced into the reactor vessel through an end (30) of the inner pipe, and wherein a protective gas can be introduced into the reactor vessel through an end (32) of the outer pipe in the peripheral space between the inner pipe and the outer pipe.

2. The reactor of claim 1, wherein the reactor is at least one of a fluidized bed reactor, a circulating fluidized bed reactor, a bubbling bed reactor, a spouted bed reactor, slugging bed reactor, a riser type reactor, a vertical shaft (furnace type) reactor, a moving bed reactor, and a cyclone reactor.

3. The reactor of any one of claims 1 to 2, wherein the end (32) of the outer pipe (26) is flush with an inner surface of the protective lining (16) or extends beyond an inner surface of the protective lining into the reactor vessel (12).

4. The reactor of any one of claims 1 to 3, wherein the end (30) of the inner pipe (24) is flush with the end (32) of the outer pipe (26).

5. The reactor of any one of claims 1 to 3, wherein the end (30) of the inner pipe (24) extends beyond the end (32) of the outer pipe (24) into the reactor vessel (12) or the end of the inner pipe is recessed within the end of the outer pipe.

6. The reactor of any one of the previous claims, wherein the peripheral space (28) extends around the entire outer periphery of the end of the inner pipe (24).

7. The reactor of any one of the previous claims, further comprising: at least one of a second inlet tube (34) extending into the reactor vessel for injecting titanium feedstock into the reactor vessel, a third inlet tube (36) extending into the reactor vessel for injecting a carbon feedstock into the reactor vessel, and an exhaust opening (38) at a top end of the reactor vessel for exhausting a gas stream containing titanium tetrachloride from inside the reactor, and optionally a second said double-walled inlet tube (22) for the chlorination agent containing gas extending into the reactor vessel through the protective lining, and optionally wherein the first said and optionally second said double-walled inlet tubes extend into the reactor near a bottom end of the reactor vessel, and optionally wherein the protective lining (16) comprises heat resistant refractory material, wherein optionally the refractory material comprises refractory bricks lining the inside wall of the reactor vessel.

8. A method of injecting a chlorination agent containing gas into a reactor vessel (12) of a reactor (10) having a double-walled inlet tube (22) for the carbochlorination process of forming titanium tetrachloride from titanium feedstock using carbonaceous material as a reducing agent, the method comprising: injecting the chlorination agent containing gas into the reactor vessel through an end (30) of an inner pipe (24) of the double-walled inlet tube; and simultaneously injecting a protective gas into the reactor vessel through a peripheral space (28) between the inner pipe and an end (32) of an outer pipe (26) of the double-walled inlet tube.

9. The method of claim 8, wherein the protective gas forms a protective gas envelope around the end (30) of the inner pipe and the end (32) of the outer pipe, and optionally wherein the chlorination agent containing gas comprises a chlorination agent comprising one or more of chlorine, phosgene (COCI2), carbon tetrachloride (CCI4), thionyl chloride (SOCI2), and / or sulfuryl chloride (SO2CI2).

10. The method of any one of claims 8 to 9, wherein the chlorination agent containing gas is injected into the reactor vessel at a first velocity (Vi), and the protective gas is injected into the reactor vessel at a second velocity (Vo), wherein the second velocity is equal to or greater than the first velocity.

11. The method of any one of claims 8 to 10, wherein the chlorination agent containing gas is injected at a first temperature and the protective gas is injected at a second temperature, wherein the second temperature is lower than the first temperature.

12. The method of any one of claims 8 to 11, wherein the protective gas comprises an inert gas, preferably comprising at least one of carbon monoxide (CO), carbon dioxide (CO2), and nitrogen gas (N2).

13. The method of any one of claims 8 to 12, wherein the protective gas comprises a reactive gas, preferably comprising at least one of titanium tetrachloride (TiCI4), chlorine gas (CI2), and carbon tetrachloride (CCI4).

14. The method of claim 13, wherein the second temperature of the protective gas is at least about 100 °C or more cooler than the first temperature of the chlorination agent containing gas and above the condensation temperatures of each of the chlorination agent containing gas and the protective gas.

15. The method of any one of claims 8 to 14, wherein the reactor comprises the reactor (10) of any one of claims 1 to 7.

16. The method of any one of claims 8 to 15, wherein the protective gas is at least partly recycled from another plant process (110, 114, 116) including the carbochlorination process and / or the protective gas is supplied from a fresh source.

17. The method of any one of claims 8 to 16, wherein at least some of the protective gas comprises recycled off-gas from the carbochlorination process, wherein the recycled off-gas preferably comprises at least one of CO2, CO, and mixtures thereof.

18. The method of any one of claims 8 to 17, wherein at least some of the protective gas comprises recycled chlorination agent from the carbochlorination process, wherein the recycled chlorination agent comprises at least one of CI2, TiCI4, COCI2, and mixtures thereof.

19. A plant process configuration (100, 200, 300, 400, 500, 600, 700) for forming titanium tetrachloride from titanium feedstock using a carbochlorination process using carbonaceous material as a reducing agent, wherein the plant process configuration comprises a reactor as recited in any one of claims 1-7.

20. The plant process configuration of claim 19, wherein the plant process configuration comprises a supply of recycled protective gases from other processes in the plant process configuration and / or a supply of fresh protective gases for supplying to the double-walled inlet tube, wherein preferably the supply of recycled protective gases comprises at least one of recycled off-gas, recycled chlorination agent, and mixtures thereof.

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