JP7428592B2 - Titanium tetrachloride manufacturing method and chlorination furnace - Google Patents

Description

The present invention relates to a method for producing titanium tetrachloride and a chlorination furnace.

Titanium tetrachloride is widely used not only as a raw material for producing spongy solid metal titanium (hereinafter referred to as "sponge titanium") but also in the fields of catalysts and medicine. Titanium tetrachloride is produced by reacting coke, which is a carbon source, titanium ore, and chlorine gas at high temperatures.

Titanium tetrachloride is produced in a fluidized bed in which ore and coke are fluidized with chlorine gas, which is formed in a chlorination furnace with a refractory structure. Titanium tetrachloride is produced under harsh conditions, and various techniques have been reported to suppress the decline in production efficiency.

For example, in Patent Document 1, "a chlorine gas dispersion plate in which a raw material containing a metal oxide and coke are placed on the upper part, and in which chlorine gas supplied from the lower part is brought into contact with the raw material, a bottom plate, A heat insulating layer made of a monolithic refractory disposed on the upper surface of the bottom plate, and a dispersion layer made of inert particles having chlorine resistance disposed above the heat insulating layer, the bottom plate and the heat insulating layer having is a dispersion board characterized by being provided with a plurality of gas channels through which chlorine gas passes."

Japanese Patent Application Publication No. 2014-210689

In the invention disclosed in Patent Document 1, corrosion of the dispersion disk due to chlorine gas can be reduced during the production of titanium tetrachloride.
By the way, in a dispersion disk provided in a chlorination furnace and having a plurality of gas passages through which chlorine gas passes, one of the gas passages may become clogged with impurities or the like derived from the chlorination reaction. In this case, chlorine gas cannot be sent into the fluidized bed through the gas flow path. As a result, it is thought that the production efficiency of titanium tetrachloride decreases because the amount of chlorine gas supplied to the fluidized bed is reduced or the balance of chlorine gas supplied from the distribution disk is lost. As described above, there is still room for improvement regarding the technology described in Patent Document 1.

Therefore, an object of an embodiment of the present invention is to provide a method for producing titanium tetrachloride that can quickly eliminate clogging of the gas flow path of a chlorination furnace.

That is, one aspect of the present invention is a method for producing titanium tetrachloride using a chlorination furnace equipped with a distribution disk in which a plurality of gas flow channels are formed, the titanium tetrachloride being produced through a gas supply pipe connected to each gas flow channel. a chlorination step in which a chlorine-containing gas is supplied into the chlorination furnace, and titanium ore, carbon, and chlorine gas are brought into contact with each other on the distribution disk to produce titanium tetrachloride; This is a method for producing titanium tetrachloride, in which the pressure in the gas flow path is measured by a pressure measurement unit, and the flow rate of gas sent from the gas supply pipe to the gas flow path is changed depending on the pressure.

In one embodiment of the method for producing titanium tetrachloride according to the present invention, the gas supply pipe includes a pipe for normal operation gas, a pipe for unclog gas, and a pipe for normal operation gas and a pipe for unclog gas. and a confluence section.

In one embodiment of the method for producing titanium tetrachloride according to the present invention, a gas containing one or more selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide is supplied from the clogging gas pipe.

In one embodiment of the method for producing titanium tetrachloride according to the present invention, part or all of the gas supply pipes connected to each gas flow path are connected to a main pipe, and the gas supply pipe connected to the main pipe is The flow rate of the chlorine-containing gas in each gas flow path is calculated by the following formula I based on the pressure difference between the pressure in the path and the pressure in the main pipe. The flow rate of the gas sent from the gas supply pipe to the gas flow path is changed when the flow rate is lower than the average flow rate of the chlorine-containing gas per unit.

In another aspect, the present invention provides a distribution plate in which a plurality of gas flow paths are formed, a gas supply pipe connected to each gas flow path, and a pressure measurement device capable of measuring the pressure in the gas flow path. It is a chlorination furnace comprising:

In one embodiment of the chlorination furnace according to the present invention, the gas supply pipe includes a pipe for normal operation gas, a pipe for declogging gas, and a confluence of the pipe for normal operation gas and the pipe for declogging gas. Equipped with.

In one embodiment of the chlorination furnace according to the present invention, a valve is provided upstream of the merging section of the normal operation gas piping, and the pressure measurement part is provided in the clogging gas piping.

In one embodiment of the chlorination furnace according to the present invention, one or more supply sources selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide are connected to the clogging gas piping.

According to one embodiment of the present invention, clogging of the gas flow path of the chlorination furnace can be promptly eliminated.

1 is a schematic diagram showing the internal structure of a chlorination furnace used in a method for producing titanium tetrachloride according to an embodiment of the present invention. FIG. 1B is a partially enlarged sectional view showing a distribution disk in the chlorination furnace of FIG. 1A. FIG. 1B is a partially enlarged sectional view showing another example of the distribution disk of FIG. 1B. FIG. 1B is a partially enlarged sectional view showing another example of the distribution disk of FIG. 1B. 1A is a schematic cross-sectional view taken along section line AA in FIG. 1A. FIG. It is a schematic diagram showing another example of the internal structure of the chlorination furnace used for the manufacturing method of titanium tetrachloride concerning one embodiment of the present invention. 2 is a schematic diagram showing the internal structure of a chlorination furnace in Comparative Example 1. FIG.

Hereinafter, specific embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and various changes can be made without departing from the gist of the present invention.

[Production method of titanium tetrachloride]
One embodiment of the method for producing titanium tetrachloride according to the present invention uses a chlorination furnace 100 shown in FIG. 1A, and includes a chlorination step for producing titanium tetrachloride. In this chlorination furnace 100, a plurality of gas passages 125 are provided in the distribution plate 120, and chlorine containing Gas is supplied. The chlorine-containing gas supplied into the chlorination furnace 100 forms a fluidized bed 150 containing titanium ore and carbon on the distribution plate 120. A chlorination reaction occurs within the fluidized bed 150, thereby producing titanium tetrachloride. While the chlorine-containing gas is being supplied, the pressure inside the gas flow path 125 is measured by the pressure measuring section, and the flow rate of the gas sent from the gas supply pipe 130 to the gas flow path 125 is changed in accordance with the pressure. For example, when a blockage occurs in the gas flow path 125, the pressure in the gas flow path 125 where the blockage occurs increases. When a relatively large amount of gas is supplied to the gas passage 125 that is determined to be clogged in a short period of time, the pressure inside the gas passage 125 increases, and the substance clogging the gas passage 125 is discharged. , the clogging of the gas flow path 125 is quickly cleared. In one embodiment, the time required for maintenance can also be reduced because the blockage is cleared without dismantling the chlorination furnace 100. Further, since the pressure in the gas flow path 125 becomes low after the clogging is cleared, the same amount of chlorine-containing gas as that during normal operation before the gas flow path 125 is cleared from clogging may be supplied thereafter. As a result, in one embodiment, it is possible to produce titanium tetrachloride stably over a long period of time.

For example, a chlorination furnace for manufacturing titanium tetrachloride shown in Patent Document 1 (see FIG. 2(a) of Patent Document 1) supplies chlorine gas to a fluidized bed via a wind box. In the chlorination furnace, chlorine gas is sent from one chlorine gas pipe to the fluidized bed via a number of gas channels in a distribution disk. Therefore, if any of the many gas channels in the distribution disk becomes clogged with impurities such as metal chlorides, it is difficult to identify which gas channel is clogged. If you try to clear the blockage by increasing the flow rate of chlorine gas from the wind box's chlorine gas piping, you would have to increase the overall flow rate of chlorine gas to clear the blockages in some of the many gas flow paths. It must be made larger than necessary. Such a method of eliminating clogging in a chlorination furnace is not practical from the standpoint of operational safety, considering the maximum permissible flow rate of chlorine gas, which depends on the durability of the wind box. In this chlorination furnace, when unblocking the gas flow path, rather than increasing the flow rate of chlorine gas from the chlorine gas piping, the chlorination furnace must be dismantled and the distribution plate taken out, and then the gas flow path must be cleared. It is thought that it will be necessary to carry out work to clear the blockages. Since such clogging work involves dismantling the chlorination furnace, there is a problem in that the work period is prolonged.

If clogging of the gas flow path itself can be suppressed, titanium tetrachloride can be efficiently produced in a chlorination furnace. However, it is unclear what mechanism causes gas flow path clogging in the production of titanium tetrachloride in a chlorination furnace. Therefore, during the production of titanium tetrachloride, clogging of the gas flow path itself cannot be avoided. Assuming that impurities contained in titanium ore are responsible for clogging the gas flow path, if the amount of chlorine gas supplied is reduced to suppress the production of substances that cause gas flow clogging, the amount of titanium tetrachloride produced would decrease. will also decrease. Therefore, such measures are undesirable.

Furthermore, the substances that cause the blockage of the gas flow path during the production of titanium tetrachloride in a chlorination furnace may include not only chlorides produced in the chlorination reaction but also oxides. For example, chloride is soluble in water, so it may be possible to remove it by supplying water. However, it is not desirable to supply water to the chlorination furnace because hydrogen chloride gas is generated when chlorides are decomposed by supplying water, which induces corrosion of piping and the like. Note that, unlike chlorides, the oxides cannot be removed by supplying water, and supplying water is not a fundamental solution to the problem of clogging the gas flow path, and there is room for improvement.

Therefore, the inventors of the present invention have diligently investigated means for eliminating the clogging of the gas flow path for supplying chlorine-containing gas to the fluidized bed, obtained the following knowledge, and have completed the present invention after further investigation. That is, in one embodiment, instead of uniformly supplying chlorine-containing gas to a plurality of gas flow paths through a wind box, a gas supply pipe for supplying chlorine-containing gas to the gas flow paths is directly connected. Furthermore, a pressure measuring section is provided in the gas supply pipe. If the gas flow path becomes clogged, pressure increases from the clogged portion to the inside of the gas supply pipe. Therefore, by checking the pressure, it is possible to determine at an early stage whether or not clogging has occurred in a particular gas flow path. If a blockage occurs in a certain gas flow path, the substance causing the blockage can be removed by changing (usually increasing) the flow rate of gas sent from the gas supply pipe to the gas flow path in accordance with the pressure change in the gas supply pipe. This makes it possible to quickly eliminate clogging in the gas flow path. During such an operation, there is no need to make any particular change in the gas flow rate in the gas passages that are not clogged, so the amount of chlorine-containing gas supplied to the fluidized bed does not change significantly. As a result, it is possible to eliminate clogging of the gas flow path without dismantling the chlorination furnace, making it possible to produce titanium tetrachloride continuously and stably over a long period of time, and also extending the life of the chlorination furnace. It can be said that it is connected.

<Chlorination furnace>
The chlorination furnace 100 includes a chlorination furnace main body 110, a distribution disk 120, a gas supply pipe 130, a wind box 140, a fluidized bed 150, a raw material supply pipe 160, and a titanium tetrachloride gas recovery pipe 170. As for the shape or material of the chlorination furnace main body 110, the distribution disk 120, the wind box 140, the raw material supply pipe 160, and the titanium tetrachloride gas recovery pipe 170, any publicly known shape or material can be adopted as appropriate. The material, shape, welding method, etc. of the gas supply pipe 130 can be appropriately determined in consideration of the properties of the gas to be supplied. The fluidized bed 150 is formed in the chlorination furnace body 110 after the production of titanium tetrachloride is started. Therefore, the fluidized bed 150 is not an essential component of the chlorination furnace 100, but rather a configuration of the chlorination furnace 100 that is formed during operation.

(Dispersion board)
The distribution disk 120 disperses the chlorine-containing gas supplied from the gas supply pipe 130 and causes it to flow into the fluidized bed 150 . The distribution plate 120 may include, for example, as shown in FIG. 1B, a bottom plate 122, a heat insulating layer 124 formed of a filler on the bottom plate 122, and a plurality of gas channels 125. Note that the chlorine concentration of the chlorine-containing gas may be appropriately determined in view of the operating state of the chlorination furnace 100, and other gases such as oxygen and nitrogen may be included as appropriate in addition to chlorine.

(Bottom plate)
The bottom plate 122 is located above the wind box 140 in the chlorination furnace main body 110, and has a plurality of gas channels 125 formed therein so that chlorine-containing gas passes therethrough. The distribution plate 120 is provided with a nozzle 126, and the upper end of the nozzle 126 extends to the fluidized bed 150 side above the heat insulating layer 124. A chlorine-containing gas is supplied to the upper side of the heat insulating layer 124 and further to the fluidized bed 150 via the gas flow path 125 in the nozzle 126 . A gas outlet 128 a formed in a side wall of a protective tube 128 surrounding the outer periphery of the nozzle 126 is provided above the heat insulating layer 124 . From the viewpoint of smooth gas blowing, it is preferable that the gas blowing ports 128a are arranged so as not to face each other. The shapes of the nozzle 126 and the protection tube 128 can be changed as appropriate. For example, in the distribution plate 120 shown in FIG. 1C, the upper end of the nozzle 126 is located within the heat insulating layer 124, and the gas outlet 128b is provided on the side wall of the protection tube 128. Further, as shown in FIG. 1D, the upper end of the nozzle 126 may be arranged near the boundary between the heat insulating layer 124 and the fluidized bed 150, and the gas outlet 128c may be provided at the upper end of the protection tube 128.
Further, from the viewpoint of heat resistance, the material of the bottom plate 122 may be one or more selected from the group consisting of carbon steel, stainless steel, and Ni, for example. Note that the thickness of the bottom plate 122 can be designed as appropriate, and is, for example, 40 to 100 mm. Carbon steel is steel with a carbon content of 2% by mass or less, and includes so-called ultra-low carbon steel, low carbon steel, medium carbon steel, high carbon steel, and the like. Specific examples of carbon steel include SS400 and the like. Stainless steel is steel to which chromium (Cr), nickel (Ni), etc. are added from the viewpoint of heat resistance and strength. Specific examples of stainless steel include ferritic stainless steel, austenitic stainless steel, martensitic stainless steel, duplex stainless steel, and the like.

(orifice)
An orifice 123 is provided on the wind box 140 side of the bottom plate 122. The diameter of the orifice 123 can be appropriately determined, for example, based on the gas flow rate and pressure loss required to disperse the chlorine-containing gas.

(insulation layer)
The heat insulating layer 124 is typically formed on the top surface of the bottom plate 122 . The heat insulating layer 124 may have a single layer structure or a multilayer structure. Furthermore, when the heat insulating layer 124 is formed by filling it with a filler made of heat-resistant ceramics, it is possible to appropriately reduce the weight of the distribution plate 120 and reduce the influence of corrosion caused by chlorine-containing gas. Examples of the filler made of heat-resistant ceramics include fillers made of silicon nitride, fused silica, or alumina. The shape of the heat-resistant ceramic filler is not particularly limited, but examples include spherical and flat shapes. Among these, the shape of the filler is preferably a flat plate from the viewpoint of durability of the dispersion disk 120. Further, it is preferable that the packing material has a size such that it does not get caught up in the fluidized bed 150. Note that the thickness of the heat insulating layer 124 can be designed as appropriate, and is, for example, 300 to 600 mm.
Further, as shown in the example shown in FIG. 1E, the arrangement of the gas passages 125 in the heat insulating layer 124 is as follows when the inside of the heat insulating layer 124 is viewed from above, from the viewpoint of uniformly supplying the chlorine-containing gas to the fluidized bed 150. It can be divided into a central region T1 and four peripheral regions T2 to T5 divided at equal intervals in the circumferential direction between the central region T1 and the side wall 111 of the chlorination furnace main body 110. Although not shown, a plurality of gas channels 125 may be arranged at equal intervals in the central region T1 and each of the peripheral regions T2 to T5 of the heat insulating layer 124. In addition, in a top view of the heat insulating layer 124, the plurality of gas channels 125 may be arranged in a point-symmetrical relationship with respect to the central axis of the chlorination furnace main body 110, or in the height direction of the chlorination furnace 100. They may be arranged in a line-symmetrical relationship with respect to a center line that is perpendicular to the center line.
Further, the plurality of gas channels 125 in the heat insulating layer 124 are arranged in a plurality of rows from the central axis toward the side wall 111 of the chlorination furnace main body 110, and each row has a circular or polygonal shape (for example, a hexagonal, They may be arranged in an octagonal shape, etc.). Further, the number of gas channels 125 in the distribution plate 120 can be designed as appropriate, but is, for example, 60 to 120 in total.

(protection tube)
A protective tube 128 provided within the heat insulating layer 124 and extending upward surrounds the outer periphery of the nozzle 126 to protect the nozzle 126. From the viewpoint of heat resistance and wear resistance, the protection tube 128 may be made of one or more materials selected from the group consisting of silicon nitride, silicon carbide, and alumina. A gas outlet (such as 128a) is formed at the upper end of the protective tube 128 in order to supply the chlorine-containing gas from the nozzle 126 to the fluidized bed 150.
However, from the viewpoint of efficiently supplying chlorine-containing gas, the gas outlets 128a, 128b, and 128c of the protection tube 128 are arranged so as not to face the gas outlets 128a, 128b, and 128c of the adjacent protection tubes 128. It is preferable.

(Gas supply pipe)
In one embodiment shown in FIG. 1A, the gas supply pipe 130 includes a normal operation gas pipe 132, a unclog gas pipe 134, and a junction J between the normal operation gas pipe 132 and the unclog gas pipe 134. Equipped with.

(Normal operation gas piping)
The normal operation gas pipe 132 passes through the wind box 140, and its end is connected to the nozzle 126, and the other end is connected to the main pipe 136, which is a chlorine-containing gas supply source. The normal operation gas pipe 132 is provided with a valve V1 on the upstream side (gas supply source) side of the confluence section J. Further, a check valve may be installed between the confluence J of the normal operation gas pipe 132 and the valve V1, or a check valve may be installed upstream of the valve V1. By doing so, it is possible to more reliably prevent gas from flowing from the clogging gas pipe 134 to the main pipe 136.

(Clog-resolving gas piping)
In one embodiment shown in FIG. 1A, the unclog gas line 134 is capable of delivering gas at a higher pressure than the pressure within the normal operating gas line 132 to unclog the gas flow path 125. be. The clogging gas pipe 134 is connected to the normal operation gas pipe 132 at the confluence J, and a valve V2, a valve V3, and a pressure measuring part PG1 are provided between the valves V2 and V3. The clogging gas piping 134 may be connected to a gas supply source (not shown) in order to supply gas at a pressure higher than the pressure of the chlorine-containing gas supplied from the normal operation gas piping 132. Moreover, it is preferable that the clogging gas piping 134 is provided with a supply source of a gas containing one or more selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide. Air is preferable as the gas from the viewpoint of cost and safety in the work of removing blockages. Air mainly contains nitrogen and oxygen, and is included in the above gases. Further, when it is assumed that the clogging-causing substance contains an oxide, by supplying a gas containing carbon monoxide, it is expected that the clogging will be eliminated based on the reduction of the oxide.

(Pressure measurement part)
The pressure measurement unit PG1 can measure the pressure inside the clogging gas pipe 134, and can determine whether the gas flow path 125 (or nozzle 126) is clogged based on the measured pressure value. When supplying chlorine-containing gas to the fluidized bed 150, valves V1 and V3 are open, and valve V2 is closed. When the gas flow path 125 is clogged, the gas flow path 125 becomes narrow at the clogged location, making it difficult for the chlorine-containing gas to flow. The pressure inside increases. In the operation of the chlorination furnace 100, while the chlorine-containing gas is being supplied from the main pipe 136, the pressure inside the clogging gas pipe 134 is continuously or intermittently measured by the pressure measurement part PG1. By doing so, the presence or absence of clogging in the gas flow path 125 is monitored. During the clog clearing operation, valve V1 is closed and valves V2 and V3 are open. Immediately after starting gas supply from the clogging-removal gas piping 134, the measured value of the pressure measurement unit PG1 increases, but once the clogging is removed, the pressure decreases. By checking the decrease in pressure within the clogging gas pipe 134, it is possible to detect whether or not the gas flow path 125 is unclogged. Note that since the flow of gas toward the main pipe 136 is blocked by the valve V1, the pressure in the clogging gas pipe 134 measured by the pressure measurement part PG1 is approximately the same as the pressure in the gas flow path 125. It can be.
When maintenance of the clogging gas piping 134 and its upstream equipment or maintenance of the pressure measurement part PG1 becomes necessary, leakage of chlorine-containing gas can be appropriately prevented by closing the valve V3.
In one embodiment shown in FIG. 1A, the clogged gas flow path 125 is targeted for clogging removal work, and the other gas flow paths 125 maintain the flow rate of the chlorine-containing gas, thereby reducing the effect on the fluidized bed 150. It is. From this viewpoint, in the chlorination furnace 100, the ratio (B/A) of the number of valves V1 (B) to the number of gas flow paths 125 (A) is, for example, 0.9 or more.

(former pipe)
In one embodiment shown in FIG. 1A, source tube 136 is a source of chlorine-containing gas. The main pipe 136 is provided with a pressure measurement part PG2 and is connected to the normal operation gas pipe 132. Although not shown, a part of the normal operation gas pipe 132 connected to each gas flow path 125 is connected to the main pipe 136, and the remaining normal operation gas pipe 132 is connected to another main pipe. You can. That is, the number of supply sources for the chlorine-containing gas may be one or two or more.

(wind box)
The wind box 140 is provided below the chlorination furnace main body 110. The wind box 140 has a dispersion plate 120 arranged so as to close the upper opening thereof. In one embodiment shown in FIG. 1A, a plurality of normal operation gas pipes 132 are inserted into the wind box 140, respectively. In one embodiment, the merging section J, the clogging gas piping 134, the pressure measuring section PG1, etc. are arranged outside the wind box 140. Note that one or more of these may be arranged within the wind box 140. Since the chlorine-containing gas is supplied to the fluidized bed 150 without coming into contact with the wind box 140, the wind box 140 is not an essential component of the chlorination furnace 100. However, it is preferable that the chlorination furnace 100 includes a wind box 140, since this is a useful configuration as a countermeasure against leakage of chlorine-containing gas in the unlikely event of a leak. As for the shape of the wind box 140 or the material of the surrounding wall that partitions the wind box 140, publicly known shapes can be adopted as appropriate.

(Fluidized bed)
A fluidized bed 150 is formed on the dispersion plate 120 during operation of the chlorination furnace 100. The fluidized bed 150 is formed containing a metal oxide raw material, coke as a carbon source, and chlorine-containing gas, and maintains a fluidized state. Titanium tetrachloride gas is produced by the metal oxide raw material, coke, and chlorine-containing gas coming into contact and reacting under high-temperature conditions. The metal oxide raw material may be a titanium ore containing titanium oxide.

(raw material supply pipe)
The raw material supply pipe 160 is provided on the side wall 111 of the chlorination furnace main body 110 at a position higher than the distribution plate 120 in the thickness direction of the distribution plate 120 in order to supply titanium ore and coke to the fluidized bed 150. The shape or material of the raw material supply pipe 160 can be appropriately selected from known ones. In addition, in the facility of the chlorination furnace main body 110, the raw material supply pipe 160 may be inserted between the bricks of the side wall 111.

(Titanium tetrachloride gas recovery pipe)
The titanium tetrachloride gas recovery pipe 170 is provided near the top of the chlorination furnace body 110 in order to recover titanium tetrachloride gas generated within the chlorination furnace body 110. At this time, the recovered titanium tetrachloride gas is sent from the titanium tetrachloride gas recovery pipe 170 to a condenser (not shown), and in the condenser, the titanium tetrachloride gas is cooled to below the boiling point of titanium tetrachloride, 136°C. , it can be recovered as liquid titanium tetrachloride. Further, the shape or material of the titanium tetrachloride gas recovery pipe 170 can be appropriately selected from known ones.

(Other examples of chlorination furnace)
Further, in a chlorination furnace 200 shown in FIG. 2 as another embodiment, unlike the chlorination furnace 100 described above, the gas supply pipe 230 is connected to the downstream side via the branch part B from the viewpoint of reducing the load on equipment maintenance. It is equipped with a normal operation gas pipe 232 branching toward the normal operation gas pipe 232, a clogging-removal gas pipe 234 connected to the normal operation gas pipe 232, and a main pipe 236 to which each normal operation gas pipe 232 is connected. Equipped with. The branched normal operation gas pipe 232 is inserted into the wind box 140 and connected to each gas flow path 125 of the distribution board 120. Note that a plurality of branch points may be provided between the main pipe 236 on the upstream side and the gas flow path 125 on the downstream side. Branch B may be provided downstream of valve V1. Thereby, the amount of chlorine-containing gas can be controlled by grouping the plurality of gas channels 125 together. Further, the branching portion B may be provided on the downstream side of the merging portion J. Thereby, it is possible to switch between normal operation and clogging removal work for each of the plurality of gas flow paths 125 as a group, that is, for each fixed area. Further, a part of the normal operation gas pipe 232 may be connected to the main pipe 236, and the remaining normal operation gas pipe 232 may be connected to another main pipe. In another embodiment shown in FIG. 2, a plurality of gas channels 125 located in the central region T1 and a plurality of gas channels 125 located in each of the peripheral regions T2 to T5 each have a branch portion B. The gas supply pipe 230 is used to collectively control the supply of chlorine-containing gas, etc.
As shown in the chlorination furnace 200 as an example, when the gas supply pipe 230 is used to control the supply of chlorine-containing gas using a plurality of gas flow paths 125 as one unit, from the viewpoint of reducing the maintenance load, the gas flow path The ratio (B/A) of the number of valves V1 (B) to the number of valves V1 (A) is, for example, less than 0.9.

(Manufacturing example)
In one embodiment, an example of manufacturing titanium tetrachloride using the chlorination furnaces 100 and 200 will be described.
In the production of titanium tetrachloride, during normal operation (gas flow path 125 is not clogged), valve V2 provided upstream of pressure measurement section PG1 is closed, and valve V3 provided downstream of pressure measurement section PG1 is closed. In the open state, chlorine-containing gas is supplied to the fluidized bed 150 containing titanium ore and coke through the gas flow path 125 directly connected to the normal operation gas pipes 132 and 232. At this time, the chlorine-containing gas is supplied from the normal operation gas pipes 132, 232 to the gas flow path 125, and the pressure inside the clog-resolving gas pipes 134, 234 is measured by the pressure measurement unit PG1. If the gas flow path 125 is not clogged, its pressure value will be stable at a low pressure. On the other hand, if clogging occurs in the gas flow path 125 during the supply of chlorine-containing gas, the pressure value in the clogging gas piping 134, 234 measured by the pressure measurement unit PG1 increases. For example, if the pressure value exceeds a predetermined reference value, it is determined that the gas flow path 125 is clogged. When the gas flow path 125 becomes clogged, the valve V1 of the normal operation gas piping 132, 232 connected to the clogging gas piping 134, 234 whose pressure value has increased is closed to stop the supply of chlorine-containing gas, and the clogging is removed. The valve V2 of the clogging gas piping 134, 234 is opened, and gas is supplied from the gas supply source so that the pressure in the clogging gas piping 134, 234 is higher than the pressure in the clogging gas piping 134, 234 during normal operation. Until the gas flow path 125 is unclogged, the pressure value in the clogging gas piping 134, 234 at the pressure measurement unit PG1 will be high; The pressure value inside the clogging gas pipes 134, 234 decreases and becomes stable. When the gas flow path 125 is cleared of clogging, the valve V2 of the unclogging gas pipes 134 and 234 is closed, and the valve V1 of the normal operation gas pipe 132 and 232 is opened, and the supply source of the chlorine-containing gas is opened. The chlorine-containing gas is again supplied from the main pipes 136 and 236 to the fluidized bed 150 via the gas flow path 125.

Here, gas may be continued to be supplied from the clog-removal gas pipes 134 and 234 until the gas flow path 125 is completely unblocked. Further, the clogging gas piping reaches a point where it can be confirmed from the pressure value in the clogging gas piping 134, 234 at the pressure measurement unit PG1 that the clogging in the gas flow path 125 has been partially cleared. Gas may continue to be supplied from 134 and 234. Thereafter, the valve V2 of the clogging gas piping 134, 234 is closed, and the valve V1 of the normal operation gas piping 132, 232 is opened, and the chlorine-containing gas is again supplied from the main pipe 136, 236, which is the supply source of the chlorine-containing gas. The gas may be supplied to the fluidized bed 150 via the gas flow path 125.

Note that if a check valve is installed between the confluence J of the normal operation gas pipes 132, 232 and the valve V1, or if the check valve is installed upstream of the valve V1, the unblocked gas pipes 134, 234 The gas supplied from the main pipe 136 is blocked by the check valve and is not supplied to the main pipe 136. As a result, it is possible to more reliably recognize the pressure inside the clog-removal gas pipes 134, 234.

When unblocking the gas flow path 125 as described above, the gas flow path 125 that is not clogged among the plurality of gas flow paths 125 may continue to use the normally operating gas pipes 132 and 232. On the other hand, by changing the flow rate of gas from the clogging gas piping 134, 234 connected to the clogged gas passage 125 via the confluence J, the clogging of the gas passage 125 can be eliminated. Therefore, not only can the clogging of the gas passage 125 be detected accurately, but also the clogging of the gas passage 125 can be eliminated without dismantling the chlorination furnaces 100 and 200. Furthermore, since the gas passage 125 can be unclogged at an early stage, it is possible to reliably produce titanium tetrachloride continuously and stably over a long period of time.

In the above, when determining that the gas flow path 125 is clogged, for example, if the pressure within the gas flow path 125 satisfies the following relational expression (1), chlorine-containing gas is discharged from the normal operation gas piping 132, 232. What is necessary is to temporarily stop the supply and increase the flow rate of the gas sent from the clogging gas piping 134, 234 to the gas flow path 125.
Moreover, it is preferable to supply a gas containing one or more selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide from the clogging gas pipes 134 and 234. Among them, air can be preferably used from the viewpoint of cost and safety in the work of removing blockages. Note that air mainly contains nitrogen and oxygen, and is included in the above gases. Further, when it is assumed that the clogging-causing substance contains an oxide, by supplying a gas containing carbon monoxide, it is expected that the clogging will be eliminated based on the reduction of the oxide.
1.2≦C/D...Relational expression (1)
C: Pressure value in the clogging gas piping that is higher than the pressure value in the clogging gas piping during normal operation (MPa)
D: Pressure value in the clogging gas piping during normal operation (MPa)

The pressure within the normal operation gas piping 132, 232 of the chlorine-containing gas supplied during normal operation (that is, the pressure measured by the pressure measuring part PG1) is within the range of 20 to 200 kPa in gauge pressure. preferable. Furthermore, the pressure inside the clog-resolving gas pipes 134 and 234 when the gas flow path 125 is unclogged (that is, the pressure measured by the pressure measuring part PG1) must be within the range of 60 kPa to 500 kPa in gauge pressure. is preferred. Note that the pressure in the clogging gas pipes 134, 234 when the gas flow path 125 is unclogged is higher than the pressure in the clogging gas pipes 134, 234 during normal operation.

Further, part or all of the normal operation gas pipes 132, 232 connected to each gas flow path 125 are connected to the main pipes 136, 236, respectively, and the gas pipes 132, 232 in the gas flow path 125 communicating with the main pipes 136, 236 are connected to the main pipes 136, 236, respectively. The flow rate of the chlorine-containing gas in the gas flow path 125, which is calculated by the following formula I based on the differential pressure between the pressure and the pressure inside the main pipes 136, 236, is the gas flow calculated from the flow rate of the main pipes 136, 236. The flow rate of the gas sent from the gas supply pipes 130, 230 to the gas passage 125 may be changed when the flow rate of the chlorine-containing gas per passage (also referred to as the average flow rate) is lower. By doing so, the clogging of the gas flow path 125 can be more reliably eliminated, so that titanium tetrachloride can be reliably produced continuously and stably over a long period of time. The average flow rate may be determined by dividing the flow rate of the main pipe by the number of gas flow paths 125. The pressure in the gas flow path 125 is the pressure in the clog-removal gas pipes 134 and 234 measured by the pressure measurement unit PG1. Further, the pressure within the main pipes 136, 236 is the pressure within the main pipes 136, 236 measured by the pressure measurement unit PG2.
In addition, in one embodiment, the flow path length in the following number I means the length in the longitudinal direction of the normal operation gas pipes 132, 232, and the flow path diameter is the inner diameter of the normal operation gas pipes 132, 232. means.
Further, the viscosity μ of the chlorine-containing gas in the following number I means the viscosity of the chlorine-containing gas per temperature. Regarding the viscosity μ of the chlorine-containing gas, for example, if the chlorine-containing gas at 20°C is 95% by volume of chlorine gas and 5% by volume of oxygen gas, the weighted average is calculated from the viscosity of each gas and the proportion of each gas. (0.0132 (viscosity of chlorine gas at 20°C) mPa·s×95+0.0203 (viscosity of oxygen gas at 20°C)×5)÷100=0.135. The viscosity of each gas is available in chemical handbooks or commercial databases.

The above number I is established by combining the following number II which is a pressure loss formula, the following number III which indicates the Reynolds number Re, and the following number IV which indicates the pipe loss coefficient λ. By doing so, the flow rate u of the chlorine-containing gas flowing into the normal operation gas pipes 132 and 232 can be calculated from the pressure values measured by the pressure measurement units PG1 and PG2.

Note that if the pressure inside the unclogged gas pipes 134, 234 does not decrease even after performing the operation to unclog the gas flow path 125, it is also possible to stop the operation of the chlorination furnaces 100, 200. After stopping the operation of the chlorination furnaces 100 and 200, the distribution disk 120 is removed from the chlorination furnace 100 and 200, and if the distribution disk 120 is worn out, it is replaced with an unused distribution disk, and the gas flow path 125 is removed. What is necessary is just to connect the normal operation gas pipes 132 and 232 for each case. By doing so, production of titanium tetrachloride can be restarted. Furthermore, since it is possible to know the number and position of gas passages 125 that are not clogged and the number and position of gas passages 125 that are clogged, chlorine is supplied to the chlorination furnaces 100 and 200 based on these information. It is also possible to continue producing titanium tetrachloride while changing the amount of supplied gas as appropriate.

EXAMPLES Hereinafter, the content of the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way. Note that "pressure" means the pressure measured by the pressure measurement unit.

[Example 1]
In Example 1, a chlorination furnace was assembled that included a chlorination furnace main body, a distribution disk consisting of a bottom plate and a heat insulating layer, a wind box, a fluidized bed, a raw material supply pipe, and a titanium tetrachloride gas recovery pipe. The distribution disk has a total of 60 units (arranged in multiple rows from the central axis of the chlorination reactor body toward the side wall of the chlorination reactor main body, and each row is arranged approximately concentrically) to feed chlorine gas into the fluidized bed. ) gas flow paths were provided at equal intervals. Each gas flow path and each normal operation gas pipe were connected via a wind box. Each normal operation gas pipe was connected to the main pipe. That is, as shown in FIG. 1B, one normal operation gas pipe 132 was connected to one gas flow path 125, and 60 normal operation gas pipes were connected to the main pipe. A clogging gas pipe was connected to each normal operation gas pipe. The valve provided in each normal operation gas pipe was provided upstream of the confluence of the normal operation gas pipe and the clog-removal gas pipe. As shown in FIG. 1A, each clogging gas pipe was provided with two valves V2 and V3, and further provided with a pressure measurement part PG1 installed between the valves V2 and V3. Note that, as shown in FIG. 1A, a nozzle 126 is arranged on the distribution plate 120, and the nozzle 126 is covered with a protection tube 128, and the gas outlet 128a of the protection tube 128 is connected to the inside of the fluidized bed 150 (that is, from the heat insulating layer 124). above).

The operation of the chlorination furnace was started to produce titanium tetrachloride. Titanium ore and coke, which is a carbon source, are appropriately supplied from the raw material supply pipe, and chlorine-containing gas is introduced through a nozzle connected to each normal operation gas pipe to maintain the titanium ore and coke in a fluid state. Meanwhile, the temperature of the fluidized bed was maintained at about 1000°C to carry out the chlorination reaction continuously.

While chlorine gas is being supplied from the main pipe, the pressure in the main pipe and the pressure in each gas flow path are obtained by measuring the pressure in the pressure measuring section, and the flow rate in each gas flow path is calculated using the above formula I. It was implemented while maintaining the same. Six months after starting the operation of the chlorination furnace to produce titanium tetrachloride, the flow rate of one of the 60 gas channels decreased by 10% compared to the average of each gas channel. It was inferred that the reason for this decrease in flow rate was that the gas flow path was clogged with impurities derived from the chlorination reaction. Therefore, while continuing to supply chlorine gas from the main pipe, the valve of the normal operation gas pipe connected to the gas flow path whose flow rate has decreased by 10% was closed, and the valve connected to the normal operation gas pipe was closed. Air was supplied from the clogging gas pipe. At this time, the flow rate of air supplied from the clogging gas piping to the gas flow path is set to 1.5 times the flow rate when chlorine-containing gas is flowed through the normal operation gas piping. was resolved. Note that the pressure when air was supplied from the unclogging gas pipe was about twice that when air was supplied from the normal operation gas pipe. After that, if it was determined that the gas flow path was clogged, the same operation was performed to clear the gas flow path.

As a result, the chlorination furnace could be operated continuously for about four years without dismantling the distribution disk inside the chlorination furnace.

[Comparative example 1]
In Comparative Example 1, as shown in FIG. 3, a chlorination furnace main body 310, a distribution plate 320 consisting of a bottom plate 322 and a heat insulating layer 324, a wind box 340 provided with chlorine gas piping 332, and a fluidized bed 350. A chlorination furnace 300 including a raw material supply pipe 360 and a titanium tetrachloride gas recovery pipe 370 was assembled. Note that a nozzle 326 was arranged in the gas flow path 325 of the dispersion plate 320, and the nozzle 326 was covered with a protection tube 328, and a gas outlet was provided in the protection tube 328 so as to be located in the fluidized bed 350.

The operation of the chlorination furnace 300 was started in order to produce titanium tetrachloride in the chlorination furnace 300. Titanium ore and coke are appropriately supplied from the raw material supply pipe 360, and chlorine gas is introduced from the chlorine gas pipe 332 through the nozzle 326 to maintain the titanium ore and coke in a fluidized state while controlling the temperature of the fluidized bed 350. was maintained at about 1000°C to carry out the chlorination reaction continuously.

In the second year since the chlorination furnace 300 started operating to produce titanium tetrachloride, the amount of titanium tetrachloride gas produced per hour had decreased. The reason for the decrease in the production amount of titanium tetrachloride gas was presumed to be that the gas flow path 325 was clogged with impurities derived from the chlorination reaction. Therefore, the operation of the chlorination furnace 300 was stopped in order to disassemble the chlorination furnace 300 and replace the distribution disk 320 with another distribution disk. That is, the chlorination furnace 300 could be operated for two consecutive years.

(Consideration based on examples)
In the operation of the chlorination furnace of Example 1, titanium tetrachloride could be produced continuously and stably over a long period of time compared to the operation of the chlorination furnace of Comparative Example 1. It was also confirmed that during the operation of the chlorination furnace of Example 1, the time required for maintenance was shortened because the chlorination furnace was not dismantled. Therefore, in Example 1, during the supply of chlorine-containing gas, the pressure in the gas flow path is measured by the pressure measuring section, and the flow rate of the gas sent from the gas supply pipe to the gas flow path is changed according to the pressure. It can be said that it is useful to do so.

On the other hand, in the operation of the chlorination furnace 300 of Comparative Example 1, chlorine gas is supplied from the chlorine gas piping 332 to the nozzle 326 via the wind box 340, so it is difficult to identify the nozzle 326 that is clogged. It can be said that it was difficult. Furthermore, in the operation of the chlorination furnace 300 of Comparative Example 1, in order to open the wind box 340, it is necessary to stop the supply of chlorine gas and stop the production of titanium tetrachloride.

100, 200, 300 Chlorination furnace 110, 310 Chlorination furnace main body 111 Side wall 120, 320 Distribution plate 122, 322 Bottom plate 123 Orifice 124, 324 Heat insulation layer 125, 325 Gas flow path 126, 326 Nozzle 128, 328 Protection tube 128a, 128b, 128c Gas outlet 130, 230 Gas supply pipe 132, 232 Normal operation gas pipe 134, 234 Clogging-removal gas pipe 136, 236 Main pipe 140, 340 Wind box 150, 350 Fluidized bed 160, 360 Raw material supply pipe 170, 370 Titanium tetrachloride gas recovery pipe 332 Chlorine gas pipe B Branch section J Confluence section PG1, PG2 Pressure measurement section T1 Central region T2 to T5 Surrounding region V1, V2, V3 Valve

Claims (8)

A method for producing titanium tetrachloride using a chlorination furnace equipped with a distribution plate in which a plurality of gas channels are formed, the method comprising:
Chlorination in which a chlorine-containing gas is supplied into the chlorination furnace through a gas supply pipe connected to each gas flow path, and titanium ore, carbon, and chlorine gas are brought into contact with each other on the distribution disk to produce titanium tetrachloride. including the process,
During the supply of the chlorine-containing gas, the pressure in the gas flow path is measured by a pressure measurement unit, and the flow rate of the gas sent from the gas supply pipe to the gas flow path is increased in response to an increase in the pressure. Method for producing titanium tetrachloride. The titanium tetrachloride gas supply pipe according to claim 1, wherein the gas supply pipe includes a pipe for normal operation gas, a pipe for clogging removal gas, and a confluence part of the pipe for normal operation gas and the pipe for clogging removal gas. Production method. The method for producing titanium tetrachloride according to claim 2, wherein a gas containing one or more selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide is supplied from the clogging gas pipe. A part or all of the gas supply pipe connected to each gas flow path is connected to the main pipe,
The flow rate of the chlorine-containing gas in each gas flow path, which is calculated by the following formula I, is the flow rate of the main pipe based on the pressure difference between the pressure in the gas flow path connected to the main pipe and the pressure in the main pipe. Any one of claims 1 to 3, wherein the flow rate of the gas sent from the gas supply pipe to the gas flow path is increased when the flow rate of the chlorine-containing gas per gas flow path is lower than the average flow rate of the chlorine-containing gas per gas flow path calculated from the above. The method for producing titanium tetrachloride according to item 1.
A distribution plate in which multiple gas flow paths are formed,
A gas supply pipe connected to each gas flow path,
and a pressure measurement unit capable of measuring the pressure in the gas flow path,
The gas supply pipe has a means for increasing the flow rate of gas in the gas supply pipe when the pressure measuring section detects an increase in pressure . The chlorination furnace according to claim 5, wherein the gas supply pipe includes a pipe for normal operation gas, a pipe for clogging removal gas, and a confluence part of the pipe for normal operation gas and the pipe for clogging removal gas. A valve is provided upstream of the confluence part of the normal operation gas piping,
The chlorination furnace according to claim 6, wherein the pressure measuring section is provided in the clogging gas piping. The chlorination furnace according to claim 6 or 7, wherein one or more supply sources selected from chlorine, oxygen, nitrogen, carbon monoxide, and carbon dioxide are connected to the clogging gas piping.