Method for producing titanium tetrachloride

Abstract

To provide a method for producing titanium tetrachloride that can improve the yield in the production of titanium tetrachloride.SOLUTION: A method for producing titanium tetrachloride involves forming a fluidized bed including titanium ore containing titanium oxide, coke, and chlorine gas on a dispersion board by using a chlorination furnace equipped with the dispersion board. The method includes an estimation step of estimating a height of the fluidized bed, and in the estimation step, the height of the fluidized bed is estimated based on fluidized bed information obtained by measuring internal pressure in two or more fluidized bed formation regions differing in positions in the height direction.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing titanium tetrachloride.

Background Art

[0002] Titanium tetrachloride is widely used not only as a raw material for producing sponge-like solid metallic titanium (hereinafter referred to as "sponge titanium") but also in the fields of catalysts or pharmaceuticals. Titanium tetrachloride is produced by reacting coke, which is a carbon source, titanium oxide contained in titanium ore, and chlorine gas at a high temperature.

[0003] The production of titanium tetrachloride is carried out in a fluidized bed formed by fluidizing ore and coke formed in a chlorination furnace having a refractory structure with chlorine gas. In the production of titanium tetrachloride using a chlorination furnace, unreacted titanium ore and coke may be transferred from the fluidized bed together with chlorine gas to titanium tetrachloride recovery equipment on the downstream side of the production process through a titanium tetrachloride recovery pipe at the upper part of the chlorination furnace. In such a case, the production yield of titanium tetrachloride will decrease. In order to suppress such a decrease in the production yield, for example, the technique described in Patent Document 1 has been reported.

[0004] Patent Document 1 describes "a method for producing titanium tetrachloride using a fluidized chlorination furnace, characterized in that after a first reducing agent is introduced into the fluidized chlorination furnace to form a fluidized bed, a second reducing agent having a calcium concentration higher than that of the first reducing agent is introduced into the fluidized chlorination furnace in order to control the temperature in the fluidized bed within a predetermined temperature range."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, in producing the required amount of titanium tetrachloride in a chlorination furnace, in order to appropriately control the production reaction of titanium tetrachloride in the fluidized bed formation region (hereinafter also referred to as the "fluidized bed"), it is important to accurately grasp the height of the fluidized bed. It is known that the height of the fluidized bed is typically determined according to the bulk density of the raw materials charged into the chlorination furnace, the amount of raw materials charged, and the like.

[0007] However, since the side wall of the chlorination furnace is provided with an inner wall such as refractory bricks that can withstand the high-temperature heat of formation generated by the production of titanium tetrachloride, operators cannot visually observe the height of the fluidized bed from the outside of the chlorination furnace, and it is very difficult to know the height of the fluidized bed. If the height of the fluidized bed cannot be grasped and the height of the fluidized bed cannot be sufficiently ensured with respect to the chlorine gas supply amount per unit time, the reaction between titanium oxide and chlorine gas in the fluidized bed may become insufficient. In such a case, it also leads to a decrease in the production yield of titanium tetrachloride.

[0008] Therefore, in one embodiment of the present invention, an object is to provide a method for producing titanium tetrachloride capable of improving the production yield of titanium tetrachloride.

Means for Solving the Problems

[0009] As described above, the height of the fluidized bed in the chlorination furnace cannot be visually observed from the outside of the chlorination furnace. Therefore, the present inventor has intensively studied a method for knowing the height of the fluidized bed.

[0010] To grasp the height of the fluidized bed, it is conceivable to measure the internal pressure of the chlorination furnace. Here, in the region above the height position of the fluidized bed in the chlorination furnace (freeboard section), not only is it separated from the fluidized bed, but the pressure difference in internal pressure from the fluidized bed is very large, and it is not appropriate to use its internal pressure to grasp the height of the fluidized bed. In order to know the height of the fluidized bed, it is considered appropriate to measure the internal pressure of the fluidized bed formation region rather than the internal pressure of the freeboard section.

[0011] On the one hand, when measuring the internal pressure of the fluidized bed formation region in the chlorination furnace at only one location, it is necessary to convert it to the height of the fluidized bed using some coefficient for the measurement result of the internal pressure of one fluidized bed formation region. In this case, the coefficient depending on the bulk density of the titanium ore or the like is used to calculate the fluidized bed height. However, since the state of the fluidized bed varies depending on the timing of raw material input into the fluidized bed and fluctuations in the bulk density of the raw material itself, it cannot be said that highly accurate results can be obtained by the calculation using the above coefficient.

[0012] In view of these aspects, as a result of intensive studies, the present inventor has found that by estimating the height of the fluidized bed based on the fluidized bed information obtained by measuring the internal pressures of the fluidized bed formation regions at two or more positions different in the height direction, the production yield of titanium tetrachloride can be improved.

[0013] That is, in one aspect, the present invention is a method for producing titanium tetrachloride using a chlorination furnace equipped with a dispersion plate, forming a fluidized bed containing titanium ore containing titanium oxide, coke and chlorine gas on the dispersion plate, and having an estimation step of estimating the height of the fluidized bed. In the estimation step, the height of the fluidized bed is estimated based on the fluidized bed information obtained by measuring the internal pressures of the fluidized bed formation regions at two or more positions different in the height direction.

[0014] In one embodiment of the method for producing titanium tetrachloride according to the present invention, the fluidized bed information includes the differential pressure in the height direction of the internal pressures of the fluidized bed formation regions at the two or more positions.

[0015] In one embodiment of the method for producing titanium tetrachloride according to the present invention, the fluidized bed information further includes the distance between the measurement points of the internal pressures of the fluidized bed formation regions at the two or more positions in the height direction.

[0016] In one embodiment of the method for producing titanium tetrachloride according to the present invention, on the side wall of the chlorination furnace surrounding the fluidized bed, two or more openings having different positions in the height direction are provided, and in the estimation step, the internal pressures of the formation regions of the two or more fluidized beds are measured through the openings.

[0017] In one embodiment of the method for producing titanium tetrachloride according to the present invention, the estimation step includes supplying gas from the opening toward the fluidized bed.

Advantages of the Invention

[0018] According to one embodiment of the present invention, it is possible to provide a method for producing titanium tetrachloride that can improve the yield in the production of titanium tetrachloride.

Brief Description of the Drawings

[0019]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2A

Figure 2B

Figure 3

Embodiments for Carrying Out the Invention

[0020] The present invention is not limited to the embodiments described below, and components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment. For example, an invention may be formed by deleting some components from all the components shown in the embodiment. Note that in the drawings, there are some members shown schematically to assist in understanding the embodiments included in the invention, and the illustrated sizes, positional relationships, etc. may not necessarily be accurate. Also, in this specification, the "height direction" means a direction parallel to the vertical direction of the chlorination furnace (in the case of the illustration, the vertical direction of the chlorination furnaces 100 and 200 shown in FIGS. 1A and 2A). Also, in this specification, the "height position of the opening" means the height position of the center point of each opening (in the case of the illustration, the center points C1 to C5 of the openings 112, 114, 212, 214, 216) when viewed from the front in the height direction, as shown in FIGS. 1B and 2B. Also, in this specification, the "internal pressure" means the pressure (gauge pressure) expressed based on the atmospheric pressure.

[0021] [Method for producing titanium tetrachloride] One embodiment of the method for producing titanium tetrachloride according to the present invention is a method for producing titanium tetrachloride using a chlorination furnace 100 equipped with a dispersion plate 120 shown in FIG. 1A, the method having an estimation step of estimating the height of a fluidized bed 140 on the dispersion plate 120 based on fluidized bed information. The fluidized bed information is obtained by measuring the internal pressures in the formation regions of the fluidized bed 140 at two or more positions in the height direction of the chlorination furnace 100. The fluidized bed information includes at least the internal pressures at the two or more positions, and may further include other information. In the chlorination furnace 100, usually, the internal pressure is different between the lower side and the upper side of the fluidized bed 140. From the viewpoint of accurately determining the height of the fluidized bed 140, the fluidized bed information preferably includes the differential pressure in the height direction of the internal pressures measured at the two or more positions. From the viewpoint of more accurately determining the height of the fluidized bed 140, it is more preferable that the fluidized bed information further includes the distance L between measurement points (see FIG. 1B), which is the distance along the height direction between the measurement points of the internal pressures in the formation regions of the two or more fluidized beds 140. At this time, from the viewpoint of constantly maintaining the height of the fluidized bed 140 at a desired height, it is more preferable to continuously measure the internal pressure of the fluidized bed 140. If the internal pressure of the fluidized bed 140 is continuously measured, the change in pressure can be quickly grasped, and the necessity of measures for maintaining the height of the fluidized bed 140, such as additional charging of titanium ore and coke, can be quickly determined. Although it may be determined that "the fluidized bed is not formed" due to a sharp decrease in the measured pressure, since the chlorine gas supply amount to be supplied to the chlorination furnace cannot be determined only by the information that there is no fluidized bed, it is important to determine the "height of the fluidized bed" in the present invention. Hereinafter, a preferred embodiment of the estimation step will be described while explaining the chlorination furnace 100.

[0022] (Chlorination Furnace) The chlorination furnace 100 includes a chlorination furnace body 110, a dispersion plate 120, a wind box 130, a chlorine-containing gas pipe 150, a raw material supply pipe 160, and a titanium tetrachloride recovery pipe 170. The shapes or materials of the chlorination furnace body 110, the dispersion plate 120, the wind box 130, the chlorine-containing gas pipe 150, the raw material supply pipe 160, and the titanium tetrachloride recovery pipe 170 can be appropriately selected from known ones. The fluidized bed 140 is formed on the dispersion plate 120 in the chlorination furnace body 110 after the production of titanium tetrachloride is started. The fluidized bed 140 is a component of the chlorination furnace 100 formed during operation.

[0023] (Opening) The openings 112 and 114 are provided in the side wall 111 surrounding the fluidized bed 140 from the viewpoint of ease of measuring the internal pressure of the formation region of the fluidized bed 140. The openings 112 and 114 are provided at different positions in the height direction on the side wall 111 of the formation region of the fluidized bed 140 for measuring the internal pressure of the formation region of the fluidized bed 140 at two or more different positions in the height direction. The cross-sectional shape of the openings 112 and 114 is not particularly limited, and examples include circular and polygonal shapes. When the cross-sectional shape of the openings 112 and 114 is circular, the diameter of the openings 112 and 114 is, for example, 50 to 100 mm. At this time, it is preferable that the diameters of the openings 112 and 114 are substantially the same in consideration of affecting the measurable internal pressure. Sediments containing impurities derived from titanium ore and / or coke may occur at the lower end of the fluidized bed 140, i.e., on the upper surface of the distributor plate 120, and the lower end side of the fluidized bed 140 may not be suitable for measuring the internal pressure due to the influence of the sediments. For this reason, it may not be preferable to provide the opening 112 at the lower end of the fluidized bed 140. The ratio (H1 / H) of the distance (H1) from the center point C2 of the lower opening 112 to the upper surface of the distributor plate 120 to the distance (H) from the assumed upper surface of the fluidized bed 140 to the upper surface of the distributor plate 120 in the height direction is, for example, 0.1 to 0.4. More specifically, when the distance (H) is in the range of 1500 to 2500 mm, the distance H1 is, for example, 300 mm or more, and also for example, 500 mm or more. Thereby, the internal pressure of the fluidized bed 140 can be stably measured at the opening 112 for a long time with almost no influence of the above sediments. Also, regarding the position of the upper opening 114 in the height direction, the distance (L) between the measurement points from the center point C2 of the lower opening 112 to the center point C1 of the upper opening 114 and the distance (H1) from the center point C2 of the lower opening 112 to the upper surface of the distributor plate 120 with respect to the distance (H) from the assumed upper surface of the fluidized bed 140 to the upper surface of the distributor plate 120 in the height direction, the ratio ((L + H1) / H) is, for example, 0.2 to 0.7 from the viewpoint of clarifying the difference from the internal pressure of the lower opening 112. More specifically, when the distance (H) is in the range of 1500 to 2500 mm, the distance L between the measurement points is, for example, 300 mm or more and 500 mm or more. Thereby, the height of the fluidized bed 140 can be grasped more accurately. When measuring the internal pressure at the openings 112 and 114, in view of suppressing deposits derived from titanium ore and / or coke in the vicinity of the openings 112 and 114, gas may be supplied from the openings 112 and 114 toward the fluidized bed 140. For example, as shown in FIG. 1B, one end of each of the clogging prevention air pipes 113 and 115 is connected to the openings 112 and 114, and an air supply source (not shown) is connected to the other end of the clogging prevention air pipes 113 and 115. Further, pressure measurement pipes (not shown) are provided in the clogging prevention air pipes 113 and 115 to measure the internal pressure of the fluidized bed 140. By measuring the internal pressure in the pressure measurement pipe by the pressure detection means, the internal pressure in the formation region of the fluidized bed 140 can be obtained as the fluidized bed information. An example of the specific configuration of the clogging prevention air pipes 113 and 115 will be described later.

[0024] (Exemplification of Method for Obtaining Height of Fluidized Bed) An example of the method for obtaining the height of the fluidized bed 140 will be described below. As shown in FIGS. 1A and 1B, when there are two openings 112 and 114 (the lower opening 112 and the upper opening 114) at different positions in the height direction, the fluidized bed height H can be obtained based on the following formula (1). It is assumed that air is supplied from the openings 112 and 114 at the same flow rate. H={P L1 / (P L1 -P L2 )}×L ··· Formula (1) H: Fluidized bed height (mm) P L1 : The internal pressure (kPa) in the formation region of the fluidized bed measured by the pressure detection means of the pressure measurement pipe of the clogging prevention air pipe 113 connected to the lower opening 112 P L2 : The internal pressure (kPa) in the formation region of the fluidized bed measured by the pressure detection means of the pressure measurement pipe of the clogging prevention air pipe 115 connected to the upper opening 114 L: The distance between the measurement points, which is the distance from the center point C2 of the lower opening 112 to the center point C1 of the upper opening 114 (mm) In the operation of the chlorination furnace 100, the internal pressure measured tends to increase as the height position of the measurement point in the fluidized bed 140 decreases. Also, the above P L1 / (P L1 -P L2 ) can be used to know the tendency of the internal pressure in the formation region of the fluidized bed 140 at a certain measurement point distance. The above P L1 / (P L1 -P L2 ) can be multiplied by the above measurement point distance L to obtain the theoretical fluidized bed height H.

[0025] Also, as shown in FIG. 1D, a plurality of openings 114a to 114d may be provided at the same height position. Specifically, measurement values are obtained from the openings 114a to 114d, and the differential pressure with the opening 112 and the measurement point distance are respectively substituted into the above formula (1) to obtain the height of each fluidized bed 140. The average value of the obtained heights of the fluidized beds 140 can be the height of the fluidized bed 140. In the embodiment shown in FIG. 1D, if an obvious abnormality is confirmed in any of the numerical values of the internal pressure obtained from the pressure measurement pipes of the anti-clogging air pipes respectively connected to the openings 114a to 114d at the same height position, the height of the fluidized bed 140 may be obtained based on the above formula (1) without using the abnormal internal pressure numerical value. Note that anti-clogging air pipes 115a to d are connected to each opening. Furthermore, in the example of FIG. 1D, a plurality of openings 114a to d are provided above the fluidized bed 140, but a plurality of openings may be provided below the fluidized bed 140. For example, when the number of the openings 114a to d above the fluidized bed 140 is the same as the number of the openings below the fluidized bed 140, and the openings 114a to d above and the openings below the fluidized bed 140 are arranged at the same position in the circumferential direction, the differential pressure and the measurement point distance between each of the openings 114a to d above the fluidized bed 140 and each of the openings below the fluidized bed 140 arranged at the same position in the circumferential direction are respectively substituted into the above formula (1) to obtain the height of each fluidized bed 140. The average value of the obtained heights of the fluidized beds 140 can be the height of the fluidized bed 140.

[0026] Next, another embodiment will be described below with reference to FIGS. 2A and 2B. Each configuration of the above-described embodiment can be applied as appropriate, and redundant descriptions will be omitted.

[0027] In another embodiment, the chlorination furnace 200 shown in FIGS. 2A and 2B is provided with three openings 212, 214, and 216 on the side wall 111 at different height positions. One end of each of the clogging prevention air pipes 213, 215, and 217 is connected to the openings 212, 214, and 216, and the other end is connected to an air supply source (not shown). As described above, the clogging prevention air pipes 213, 215, and 217 may be provided with a pressure measurement pipe (not shown), and a pressure detection means may be provided on the pressure measurement pipe. The differential pressure between the internal pressures of the formation region of the fluidized bed 140 and the measurement point distance L1 (the distance from the center point C3 of the opening 212 to the center point C4 of the opening 214) from the opening 212 and the adjacent opening 214 in the height direction are substituted into the above formula (1), and the differential pressure between the internal pressures of the formation region of the fluidized bed 140 and the measurement point distance L2 (the distance from the center point C4 of the opening 214 to the center point C5 of the opening 216) from the opening 214 and the adjacent opening 216 are substituted into the above formula (1) to obtain the height of each fluidized bed 140. The average value of the obtained heights of the fluidized bed 140 can be the height of the fluidized bed 140. Alternatively, the differential pressure between the internal pressures of the formation region of the fluidized bed 140 and the measurement point distance L3 (the distance from the center point C3 of the opening 212 to the center point C5 of the opening 216) from the openings 212 and 216 may be substituted into the above formula (1) to obtain the height of the fluidized bed 140.

[0028] (Dispersion plate) The dispersion plate 120 disperses the chlorine-containing gas supplied from the chlorine-containing gas pipe 150 and flows it into the fluidized bed 140. The dispersion plate 120 may include, for example, a bottom plate 122, a heat insulating layer 124 formed of a filler on the bottom plate 122, and a plurality of gas flow paths 125 as shown in FIG. 1B. 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 appropriately contained in addition to chlorine. In addition, a known shape or material of the chlorine-containing gas pipe 150 can be appropriately adopted.

[0029] (Bottom plate) The bottom plate 122 is located above the wind box 130 in the chlorination furnace body 110, and a plurality of gas flow paths 125 are formed so that the chlorine-containing gas can pass through. The dispersion plate 120 is usually provided with nozzles (not shown), and the chlorine-containing gas may be supplied from the tips of these nozzles to the fluidized bed 140. Also, from the viewpoint of heat resistance, the material of the bottom plate 122 may be, for example, one or more selected from the group consisting of carbon steel, stainless steel, and Ni. Note that the thickness of the bottom plate 122 can be designed as appropriate, but for example, it is 40 to 100 mm. Carbon steel is steel with a carbon content of 2 mass% or less, and includes so-called extra-low carbon steel, low-carbon steel, medium-carbon steel, high-carbon steel, etc. 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 viewpoints 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.

[0030] (Heat insulation layer) The heat insulation layer 124 is usually formed on the upper surface of the bottom plate 122. The heat insulation layer 124 may have a single-layer structure or a multilayer structure. The heat insulation layer 124 may be, for example, a packed layer of heat-resistant ceramics. The thickness of the heat insulation layer 124 can be designed as appropriate, but for example, it is 300 to 600 mm.

[0031] (Wind box) The wind box 130 is provided below the chlorination furnace body 110. The dispersion plate 120 is arranged so as to close the upper opening of the wind box 130. Note that the shape of the wind box 130 or the material of the peripheral wall partitioning the wind box 130 can be appropriately adopted from known ones.

[0032] (Fluidized bed) The fluidized bed 140 is formed on the dispersion plate 120 during the operation of the chlorination furnace 100. The fluidized bed 140 is formed by including titanium ore containing titanium oxide, coke as a carbon source, and a chlorine-containing gas, and maintains a fluid state. Titanium tetrachloride gas is generated by the contact and reaction of titanium ore, coke, and chlorine-containing gas under high-temperature conditions.

[0033] (Raw material supply pipe) The raw material supply pipe 160 is connected to and provided on the side wall 111 of the chlorination furnace main body 110 at a position higher than the fluidized bed 140 in order to supply titanium ore and coke to the fluidized bed 140. The shape or material of the raw material supply pipe 160 can be appropriately selected from known ones.

[0034] (Titanium tetrachloride recovery pipe) The titanium tetrachloride recovery pipe 170 is provided near the top of the chlorination furnace main body 110 in order to recover the titanium tetrachloride gas generated in the chlorination furnace main body 110. At this time, the recovered titanium tetrachloride gas is sent from the titanium tetrachloride recovery pipe 170 to a condenser (not shown) of the titanium tetrachloride recovery facility, and the titanium tetrachloride gas can be cooled to a temperature below the boiling point of titanium tetrachloride, 136 °C, in the condenser to be recovered as liquid titanium tetrachloride. Also, the shape or material of the titanium tetrachloride recovery pipe 170 can be appropriately selected from known ones.

[0035] (Opening device) The configuration of the clogging prevention air pipe described above can be appropriately selected. For example, a three-way pipe can be used as the clogging prevention air pipe. That is, the clogging prevention air pipe 515 included in the opening device 500 shown in FIG. 3 may be connected to the opening 114. The opening device 500 has not only the function of the clogging prevention air pipe described above, that is, the function of suppressing the formation of deposits derived from titanium ore and / or coke on the opening 114, but also the function of removing the deposits formed on the opening 114. The opening device 500 shown in FIG. 3 includes a pulverizing mechanism 510, a clogging prevention air pipe 515, a valve 520, and a storage chamber 530. Note that other openings other than the opening 114 may also be provided with an opening device.

[0036] (Grinding mechanism) The grinding mechanism 510 has a rotating shaft 512, a small motor (not shown) is provided at the proximal end of the rotating shaft 512, and a bit 514 is provided at the distal end of the rotating shaft 512. The bit 514 is stored in the storage room 530 during normal operation in the operation of the chlorination furnace 100. From the viewpoints of heat resistance and wear resistance, the material of the bit 514 is preferably steel.

[0037] (Clogging prevention air pipe) The clogging prevention air pipe 515 uses a so-called three-way pipe, and one of its ends is connected to the opening 114 of the chlorination furnace 100. The other end of the clogging prevention air pipe 515 is connected to the valve 520. Further, an air supply source (not shown) is connected to the other end of the clogging prevention air pipe 515. As described above, a pressure measurement pipe (not shown) may be provided in the clogging prevention air pipe 515, and pressure detection means may be provided in the pressure measurement pipe. Note that the clogging prevention air pipe 515 shown in FIG. 3 is connected to the opening 114 of the chlorination furnace, but it may also be connected to the opening 112 shown in FIGS. 1A and 1B.

[0038] (Valve) In the operation of the chlorination furnace 100, when supplying air from the clogging prevention air pipe 515 from the viewpoint of suppressing the formation of deposits derived from titanium ore and / or coke at the opening 114, the normal valve 520 is closed. On the other hand, in the operation of the chlorination furnace 100, in order to ensure good ventilation of the opening 114 and also to deal with the case where deposits such as those derived from impurities of titanium ore and / or coke are formed at the opening 114, that is, when the pressure measured by the pressure measuring pipe is abnormally high, first the valve 520 is opened. After opening the valve 520, the rotating shaft 512 is moved horizontally by a small motor so that the bit 514 at the tip of the rotating shaft 512 passes through the valve 520, and the bit 514 is rotated in the circumferential direction of the rotating shaft 512 by the small motor to crush the deposits at the opening 114 of the chlorination furnace 100. Then, the rotating shaft 512 is moved by the small motor to return the bit 514 to the storage chamber 530, and the valve 520 may be closed.

[0039] (Storage chamber) The storage chamber 530 is connected to the valve 520. A cooling air pipe 535 is connected to the storage chamber 530. When the bit 514 crushes the deposits at the opening 114 of the chlorination furnace 100, since the fluidized bed 140 is at a high temperature of 1000 to 1100 °C, the bit 514 is exposed to and heated in the fluidized bed 140 and may soften. Therefore, after the bit 514 crushes the deposits at the opening 114 of the chlorination furnace 100, the bit 514 returned to the storage chamber 530 is cooled by cooling air. The storage chamber 530 may be provided with a cooling air exhaust pipe (not shown).

[0040] (Change in height of fluidized bed) In one embodiment, when the height of the fluidized bed obtained in the estimation step is different from the height of the fluidized bed being managed, the input of titanium ore and coke, the amount of chlorine-containing gas, etc. may be appropriately changed to obtain the desired fluidized bed height.

Example

[0041] The present invention will be specifically described based on examples and comparative examples. The following descriptions of the examples and comparative examples are merely test specific examples for facilitating the understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these specific examples.

[0042] [Example 1] First, a chlorination furnace 100 having the configuration shown in FIG. 1A was used. Further, two sets of opening devices 500 having the configuration shown in FIG. 3 were used. The opening 112 of the chlorination furnace 100 was arranged on the side wall 111 of the chlorination furnace 100 such that the separation distance (H1) from the center point C2 of the lower opening 112 to the upper surface of the dispersion plate 120 was 500 mm, and the opening 114 was arranged on the side wall 111 of the chlorination furnace 100 such that the measurement point distance (L) from the center point C2 of the lower opening 112 to the center point C1 of the upper opening 114 was 500 mm. Also, the diameter of each of the openings 112 and 114 was set to 50 mm. The clogging prevention air pipe 515 of the opening device 500 was connected to each of the openings 112 and 114. A known titanium tetrachloride recovery facility was connected to the titanium tetrachloride recovery pipe 170 of the chlorination furnace 100.

[0043] Titanium ore and coke were fed from the raw material supply pipe 160 of the chlorination furnace 100, chlorine gas was supplied from the chlorine-containing gas pipe 150, and air at the same flow rate was supplied from the openings 112 and 114, and the operation test of the chlorination furnace 100 was started. At this time, the target height of the fluidized bed 140 was set to 2000 mm, and the input amounts of titanium ore and coke were adjusted. During the operation test of the chlorination furnace 100, in order to control the target height of the fluidized bed 140, the differential pressure of the internal pressure in the formation region of the fluidized bed 140 was continuously measured through the openings 112 and 114 with different positions in the height direction, and the height of the fluidized bed 140 was calculated based on the above formula (1). During the operation test of the chlorination furnace 100, when the height of the fluidized bed 140 obtained by the above formula (1) was lower than the target height of the fluidized bed 140, the input amounts of titanium ore and coke were increased, while when the obtained height of the fluidized bed 140 was higher than the target height of the fluidized bed 140, the input amounts of titanium ore and coke were decreased. That is, during the operation test of the chlorination furnace 100, the input amounts of titanium ore and coke were appropriately adjusted so as to reach the target height of the fluidized bed 140 described above. Further, in order not to form deposits such as those derived from impurities of titanium ore and / or coke on the openings 112 and 114, the treatment was performed with the bits 514 of the pulverizing mechanism 510 of the opening device 500 every 4 hours from the start of the operation test of the chlorination furnace 100.

[0044] In the operation test of the chlorination furnace 100, the P of the above formula (1) obtained from the start of the operation test to 24 hours later L1 (The average value of the internal pressure in the formation region of the fluidized bed 140 measured by the pressure detection means of the pressure measurement pipe of the clogging prevention air pipe 515 connected to the lower opening 112) was 26.5 kPa, and P L2(The average value of the internal pressure in the formation region of the fluidized bed 140 measured by the pressure detection means of the pressure measurement pipe of the clogging prevention air pipe 515 connected to the upper opening 114) was 19.9 kPa. That is, the differential pressure between the internal pressure in the formation region of the fluidized bed 140 measured from the lower opening 112 and the internal pressure in the formation region of the fluidized bed 140 measured from the upper opening 114 was 6.6 kPa. Based on the fact that L (the distance between the measurement points, which is the distance from the center point C2 of the lower opening 112 to the center point C1 of the upper opening 114) in the above formula (1) was 500 mm, it was confirmed that the average value of the height of the fluidized bed 140 from the start of the operation test to 24 hours later was 2010 mm. In addition, P in the above formula (1) obtained from the start of the operation test to 24 hours later L1 was within the range of 26.5 ± 1.0 kPa, and P in the above formula (1) obtained from the start of the operation test to 24 hours later L2 was within the range of 19.9 ± 1.0 kPa. In addition, during the operation test of the chlorination furnace 100, the chlorine concentration in the titanium tetrachloride recovered by the titanium tetrachloride recovery facility was measured, and no increase exceeding the allowable range of the chlorine concentration was confirmed. Accordingly, it was determined that the yield of titanium tetrachloride production was good.

[0045] Next, 26 hours after the start of the operation test of the chlorination furnace 100, the height of the fluidized bed 140 was intentionally changed by introducing titanium ore with a higher bulk density than the titanium ore introduced since the start of the operation test from the raw material supply pipe 160. As a result of continuously calculating the height of the fluidized bed 140 based on the above formula (1), it was confirmed that the height of the fluidized bed 140 obtained from the above formula (1) after starting the introduction of titanium ore with a higher bulk density became lower than the height of the fluidized bed 140 obtained from the above formula (1) before introducing the titanium ore with a higher bulk density. Therefore, the height of the fluidized bed 140 was restored to the target height of the fluidized bed 140 by adding titanium ore. Although 30 hours had elapsed since the start of the operation test of the chlorination furnace 100, no increase in the chlorine concentration in titanium tetrachloride recovered by the titanium tetrachloride recovery facility exceeding the allowable range was confirmed. It is presumed that this is because, as a result of appropriately maintaining the height of the fluidized bed 140, the amounts of titanium ore, coke, and chlorine gas were appropriately controlled, and almost no unreacted chlorine was recovered. Based on this, it was determined that the yield of titanium tetrachloride production was good.

[0046] [Comparative Example 1] In Comparative Example 1, an operation test of the chlorination furnace 100 was started in the same manner as in Example 1, except that the opening 114 and the opening device 500 connected to the opening 114 were not used, that is, except that pressure was obtained only from the opening 112. Since the pressure measurement of the formation region of the fluidized bed 140 was performed only at the opening 112, the estimation using the above-described formula (1) could not be carried out. Therefore, the internal pressure of the formation region of the fluidized bed 140 was continuously measured via the opening 112 from the start of the operation test of the chlorination furnace 100 until 24 hours had elapsed, and the height of the fluidized bed 140 was calculated based on the following formula (2). H = P1 × α ··· Formula (2) H: Height of the fluidized bed 140 (cm) P1: Internal pressure of the fluidized bed 140 measured by the pressure detection means of the pressure measurement pipe connected to the opening 112 (kPa) α: Coefficient set based on the bulk density of the ore (cm / kPa)

[0047] After 26 hours had elapsed since the start of the operation test of the chlorination furnace 100, the height of the fluidized bed 140 was changed by intentionally introducing titanium ore with a higher bulk density than the titanium ore introduced since the start of the operation test from the raw material supply pipe 160. As a result of continuously calculating the height of the fluidized bed 140 based on the above formula (2), H in the above formula (2) became the same value as the desired fluidized bed height even when titanium ore with a higher bulk density was introduced. However, at the 28-hour mark since the start of the operation test, more unreacted chlorine gas was recovered from the titanium tetrachloride recovery facility downstream of the chlorination furnace 100 than usual. That is, the unreacted chlorine gas passed through the fluidized bed 140 and could not be used for the production of titanium tetrachloride, so the production yield of titanium tetrachloride decreased.

[0048] [Consideration According to the Example] Although the height of the fluidized bed cannot be directly measured, in Example 1, during the operation test of the chlorination furnace, in the estimation step, the height of the fluidized bed was accurately obtained by estimating the height of the fluidized bed based on the fluidized bed information obtained by measuring the internal pressures of two formation regions of the fluidized bed with different positions in the height direction. As a result, it was confirmed that the yield of titanium tetrachloride production was good. Even if the height of the fluidized bed changes depending on the raw material composition (TiO2, C, SiO2) in the chlorination furnace, the ore type, the bulk density of the raw material, etc., the height of the fluidized bed can be calculated from the above formula (1) at any time. Therefore, it is presumed that the yield of titanium tetrachloride production can be improved. Also, it is possible to respond quickly and accurately to changes in the raw materials used and achieve the desired height of the fluidized bed. From this perspective as well, it is presumed that the yield of titanium tetrachloride production can be improved. On the other hand, in Comparative Example 1, it was considered that the height of the fluidized bed became lower than expected due to a change in the bulk density of the ore. The reason for this is thought to be that the height of the fluidized bed could not be appropriately judged because the internal pressure of the fluidized bed formation region was only measured at one location. Also, although formula (2) was a formula considering the bulk density of the ore, the measurement accuracy of the height of the fluidized bed was lower as a result compared to formula (1). The life of the chlorination furnace often extends for several years. For example, as in Example 1, when estimating the height of the fluidized bed based on the fluidized bed information obtained by measuring the internal pressures of the formation regions of two or more fluidized beds with different positions in the height direction, the accuracy is considered high, and the improvement effect on the yield of titanium tetrachloride production is significant.

Explanation of symbols

[0049] 100, 200 Chlorination furnace 110 Chlorination furnace body 111 Side wall 112, 114, 114a~d, 212, 214, 216 Opening 113, 115, 115a~d, 213, 215, 217, 515 Anti-clogging air pipe 120 Dispersion plate 122 Bottom plate 124 Heat insulation layer 125 Gas flow path 130 Wind box 140 Fluidized bed 150 Chlorine-containing gas pipe 160 Raw material supply pipe 170 Titanium tetrachloride recovery pipe 500 Opening device 510 Crushing mechanism 512 Rotating shaft 514 Bit 520 Valve 530 Storage room 535 Cooling air pipe C1~5 Center point

Claims

1. A method for producing titanium tetrachloride using a chlorination furnace equipped with a dispersion plate, comprising forming a fluidized bed containing titanium ore containing titanium oxide, coke, and chlorine gas on the dispersion plate, wherein: the method has an estimation step of estimating the height of the fluidized bed; in the estimation step, the height of the fluidized bed is estimated based on fluidized bed information obtained by measuring the internal pressures of two or more formation regions of the fluidized bed at different positions in the height direction; two or more openings at different positions in the height direction are provided on the side wall of the chlorination furnace surrounding the fluidized bed; the estimation step includes supplying gas from the opening toward the fluidized bed, and measuring the internal pressures of the two or more formation regions of the fluidized bed through the opening, the method for producing titanium tetrachloride.

2. In the estimation step, the height of the fluidized bed is estimated based on the fluidized bed information without using the internal pressure of the freeboard portion above the height position of the fluidized bed, the method for producing titanium tetrachloride according to claim 1.

3. A method for producing titanium tetrachloride using a chlorination furnace equipped with a dispersion plate, comprising forming a fluidized bed containing titanium ore containing titanium oxide, coke, and chlorine gas on the dispersion plate, wherein: the method has an estimation step of estimating the height of the fluidized bed; in the estimation step, the height of the fluidized bed is estimated based on fluidized bed information obtained by measuring the internal pressures of two or more formation regions of the fluidized bed at different positions in the height direction without using the internal pressure of the freeboard portion above the height position of the fluidized bed, the method for producing titanium tetrachloride.

4. two or more openings at different positions in the height direction are provided on the side wall of the chlorination furnace surrounding the fluidized bed; in the estimation step, the internal pressures of the two or more formation regions of the fluidized bed are measured through the opening, the method for producing titanium tetrachloride according to claim 3.

5. An opening device equipped with a pulverizing mechanism and a clogging prevention air pipe is provided at the opening, the method for producing titanium tetrachloride according to any one of claims 1 to 2 and 4.

6. The opening device further includes a valve and a storage chamber, the method for producing titanium tetrachloride according to claim 5.

7. The fluidized bed information includes the differential pressure in the height direction of the internal pressures of the two or more formation regions of the fluidized bed, the method for producing titanium tetrachloride according to any one of claims 1 to 6.

8. The method for producing titanium tetrachloride according to claim 7, wherein the fluidized bed information further includes the distance between measurement points of the internal pressure in the formation regions of the two or more fluidized beds in the height direction.

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