JP4011571B2 - Method for preventing adhesion of high-boiling substances in distillation systems - Google Patents

Description

The present invention, malfunction due to the distillation system to distill the crude titanium tetrachloride solution containing high boilers, high boilers crude titanium tetrachloride solution crude titanium tetrachloride solution before distillation penetrate adheres The present invention relates to a method for preventing the adhesion of high-boiling substances in a distillation system for preventing water.

  Titanium metal is usually produced through steps such as production of crude titanium tetrachloride by a chlorination method, distillation purification of the produced crude titanium tetrachloride, and production of sponge titanium using purified titanium tetrachloride.

  In the production process of crude titanium tetrachloride by a chlorination method, crude titanium tetrachloride is produced in a gaseous state by bringing titanium ore containing titanium, oxygen and iron into contact with chlorine gas in the presence of carbon. Gaseous crude titanium tetrachloride produced in the reactor is liquefied by a condenser and temporarily stored in a tank.

  The produced crude titanium tetrachloride liquid contains various chloride impurities such as zirconium chloride and niobium chloride, and is sent to a distillation column or the like for removal to remove them. This is the distillation purification process of crude titanium tetrachloride.

  In a titanium tetrachloride manufacturing process including such a crude titanium tetrachloride distillation purification system, malfunctions due to adhesion of sticky substances occur in various places of the crude titanium tetrachloride liquid transfer path. One of the malfunctioning locations is a level gauge of a storage tank that temporarily stores the crude titanium tetrachloride liquid produced in the production process of crude titanium tetrachloride. As this liquid level gauge, a differential pressure type that detects the liquid level from the pressure difference between the liquid level and the liquid level is often used because of its simple structure. Malfunctions due to frequent occurrences.

  Another occurrence of malfunction is a shaft seal portion of a transfer pump in a transfer line that transfers crude titanium tetrachloride liquid to the distillation purification process. Due to adhesion and deposition of the sticking material on the shaft seal portion of the transfer pump, malfunction of the transfer pump frequently occurs.

  In order to prevent these malfunctions, the liquid level gauge and the transfer pump have been frequently disassembled and cleaned. However, such a malfunction prevention measure not only requires time and effort for disassembly and maintenance, but also requires the equipment to be shut down during the maintenance period. For this reason, economic loss is large.

  In order to prevent malfunction of the liquid level gauge due to adhesion of sticky material, a high-temperature, low-viscosity melt is introduced into the pipe connecting the liquid level gauge to melt the deposit, or a high-temperature inert gas is introduced. Although measures such as removing the deposits mechanically are described in Patent Document 1, none of the measures prevent the deposit itself, but are measures for removing the deposit when the deposit has progressed to some extent. It is difficult to completely prevent malfunction. In addition, it is necessary to stop the operation of the facility for implementation, and it cannot be said that there is no problem in terms of implementation effect and implementation cost.

JP 7-268353 A

  On the other hand, adhesion deposits on the shaft seal portion of the crude titanium tetrachloride liquid transfer pump has occurred through the following process. Originally, the shaft seal in the crude titanium tetrachloride liquid transfer pump was performed with pressurized circulating oil. However, in shaft seals with pressurized circulating oil, the oil is mixed into the crude titanium tetrachloride liquid, which is the transfer medium, and the quality deteriorates, or the titanium tetrachloride liquid is mixed into the oil and the equipment is corroded. It becomes a problem. In order to solve such a problem of mixing, a composite shaft seal structure in which natural circulation of oil and a pressurized gas are combined is described in Patent Document 2.

No. 6-14152

  Due to the complex shaft seal structure described in Patent Document 2, the problem of contamination was solved once. However, in recent years when high purity titanium is required to have a particularly high purity, it is no longer acceptable to mix a very small amount of oil, and a very small amount of oil mixed into crude titanium tetrachloride liquid through a complex shaft seal structure cannot be ignored. It has been found that

  Under these circumstances, the applicant has planned to use crude titanium tetrachloride liquid for the shaft seal in the transfer pump of crude titanium tetrachloride liquid, and the crude titanium tetrachloride liquid filtered by the filter is used for the shaft seal portion. It started to be supplied as a sealing liquid. This completely eliminated the problem of crude titanium tetrachloride liquid contamination. The reason why the crude titanium tetrachloride liquid is filtered is to remove the fine solid component present in the liquid in advance and prevent it from adhering to the shaft seal portion. However, in spite of such a contrivance, it has been found that it is unavoidable that the transfer pump frequently malfunctions due to adhesion and adhesion of the sticky substance on the shaft seal portion.

An object of the present invention is to provide a method for preventing the adhesion of high-boiling substances in a distillation system that can effectively and economically prevent malfunction due to adhesion and deposition of sticky substances in a distillation purification system of crude titanium tetrachloride.

  In order to achieve the above object, the present inventor first investigated in detail the composition of the deposits that cause the malfunction. As a result, it was found that the deposit was a high boiling point substance that was included in the crude liquid and should be removed in the distillation system. Specifically, in the case of a distillation purification system of crude titanium tetrachloride, zirconium chloride, niobium chloride, aluminum chloride, iron chloride, and the like removed by the distillation.

  Next, the present inventor planned not to remove the deposits but to prevent the deposits of these high-boiling substances, and intensively studied specific measures. When removing the deposits, the operation of the equipment is forced to stop, but if the adhesion is prevented, the operation is not stopped. The result of the study is that a liquid with a reduced high-boiling point product after distillation is supplied to the place where the adhesion occurs, and if this is the case, the adhesion that causes the malfunction is self-reliant in the system. It was found that it can be prevented completely economically.

Adhesion preventing method of high boilers in the distillation system of the present invention has been completed based on these findings, in a distillation system to distill the crude titanium tetrachloride solution containing high boilers, prior to the distillation crude titanium tetrachloride A liquid in which high boiling point substances are reduced by distillation is continuously or intermittently supplied to a portion where the liquid enters and adheres to prevent the adhering in that portion.

Specifically, as a part to prevent adhesion, a differential pressure level gauge equipped in a storage tank for crude titanium tetrachloride liquid before distillation containing high-boiling substances, or crude four- distillation liquid containing high-boiling substances before distillation. The shaft seal part in the transfer pump of a titanium chloride liquid etc. can be mentioned.

  The adhesion preventing method of the present invention is effective for a crude titanium tetrachloride liquid distillation system, particularly a crude titanium tetrachloride liquid distillation purification system in a titanium tetrachloride production process using a chlorination method.

In the adhesion preventing method of the present invention, a small amount of liquid in which high boilers are reduced by distillation is continuously or intermittently supplied to a portion where adhesion due to the penetration of crude titanium tetrachloride liquid occurs. If it does so, the part which adhesion generate | occur | produces will be sealed with the liquid in which the high boiling point substance decreased, and since supply of the high boiling point substance which is the cause of adhesion is cut off substantially by this liquid sealing, adhesion is prevented. Further, the high-boiling substances which have started to adhere are sequentially dissolved and removed by the sealing liquid in which the high-boiling substances are reduced. By these, the high boiling point substance itself is prevented. Therefore, the operation failure due to the adhesion does not occur, and the facility stop and the maintenance work for preventing the operation failure are unnecessary.

The liquid with reduced high-boiling substances used for adhesion prevention is generated in the distillation system, so it is very economical compared to the case of introducing sealing liquid, cleaning liquid, pressurized fluid for removal, etc. from outside the system. , and the addition crude four does not occur with high purity of titanium chloride solution liquid quality issues refined products for use in penetration portion of the lower crude titanium tetrachloride solution having purity.

The liquid in which the high-boiling substances used for adhesion prevention are reduced, as long as the high-boiling substances are reduced from the crude titanium tetrachloride liquid. In this case, a product (purified liquid) taken out from the distillation tower may be used, but it is economical and preferable to use a part of the circulating liquid circulating at the top of the distillation tower. The circulating fluid circulated at the top of the column is lower in purity than the purified product, but the high-boiling substances that cause adhesion have been removed in the same way as the product, and its ability as a seal solution to prevent adhesion has changed. Absent. The liquid supply amount is appropriately determined according to the object so as to obtain a desired sealing function and adhesion preventing effect.

In the distillation system according to the present invention, the method for preventing the attachment of high boiling point substances is to supply a liquid in which high boiling point substances are reduced by distillation to a part where adhesion occurs in a distillation system for distilling crude titanium tetrachloride liquid containing high boiling point substances. Then, by performing liquid sealing with this liquid, the occurrence of adhesion is prevented. Since the adhesion itself is prevented, it is possible to prevent the occurrence of the adhered material, and it is very economical because no operation stop or maintenance work is required to remove the adhered material. Since the liquid generated in the system for preventing adhesion is used as the sealing liquid, the cost required for preventing adhesion can be reduced. Since the sealing liquid used is a liquid having a higher degree of purification than the crude titanium tetrachloride liquid, it is possible to avoid quality problems due to its use.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a titanium tetrachloride production facility showing an embodiment of the present invention, and FIG. 2 is a configuration diagram of a shaft seal portion which is a main portion of a transfer pump.

  The method for preventing adhesion of high-boiling substances in the distillation system of this embodiment is used for the production of titanium tetrachloride. The production process of titanium tetrachloride includes a production system for crude titanium tetrachloride by a chlorination method and a distillation purification system for purifying the produced crude titanium tetrachloride by distillation.

  In the production system of crude titanium tetrachloride by the chlorination method, the fluidized reactor 1 is used. In the flow reaction furnace 1, in a state where granular titanium ore and granular coke are charged into the furnace, chlorine gas is blown into the furnace from the lower part of the furnace to form a fluidized bed within a temperature range of 800 to 1200 ° C. To produce gaseous crude titanium tetrachloride.

  The generated crude titanium tetrachloride gas is sequentially extracted from the top of the furnace to the outside of the furnace, sent to the cyclone 2, and after solids are removed, it is sent to the capacitor 3 and liquefied. The crude titanium tetrachloride solution generated by the capacitor 3 is once introduced into the storage tank 4. In the storage tank 4, the liquid level is measured by a differential pressure type liquid level gauge 5. The differential pressure type level gauge 5 detects the pressure difference between the liquid level in the tank and the liquid level using the liquid side conduit 6 and the space side conduit 7, and detects the liquid level from the detected value. .

  The crude titanium tetrachloride liquid in the storage tank 4 contains high-boiling substances such as zirconium chloride, niobium chloride, and aluminum chloride as described above. This crude liquid is sent by a transfer pump 8 to an evaporator 9 which is a pre-distiller. In the evaporator 9, the introduced crude titanium tetrachloride liquid is heated and gasified. The gas is extracted from the evaporator 9, liquefied by the condenser 10, and then sent to the distillation column 11. The crude titanium tetrachloride liquid in which the high boilers are concentrated in the evaporator 9 is returned to the upstream side of the cyclone 2 by the transfer pump 12.

  In the distillation column 11, the crude titanium tetrachloride liquid preliminarily distilled in the evaporator 9 is introduced into the boiler 13 at the bottom of the column to heat and evaporate. The crude titanium tetrachloride gas rises while lowering the temperature in the tower, and is finally extracted from the top of the tower. Thereby, the high boiling point substance in crude titanium tetrachloride is removed.

  The titanium tetrachloride gas extracted from the top of the distillation column 11 is returned to the liquid by the condenser 14 and circulated to the top of the column. On the other hand, pure titanium tetrachloride, which is a product, is successively taken out from the tower in a gaseous state by a so-called side cut from between the tower bottom and the tower top. The pure titanium tetrachloride gas taken out of the tower is liquefied by the condenser 22 and stored in a product tank (not shown). Thus, distillation purification in the distillation column 11 is continued, and pure titanium tetrachloride is continuously generated.

  The reason why the product is taken out by side cut from between the tower bottom and the tower top is to eliminate some of the chlorinated impurities in the low-boiling system having a boiling point lower than that of titanium tetrachloride. That is, some chlorinated impurities in the low boiling point system whose boiling point is lower than that of titanium tetrachloride are concentrated in the overhead circulating liquid. According to the side cut, some of the chlorinated impurities in the low boiling point system can be removed.

  In such a production process of titanium tetrachloride, particularly in the distillation system of crude titanium tetrachloride, high boiling point substances in the crude titanium tetrachloride become deposits, resulting in frequent malfunctions. Specifically, with a differential pressure type level gauge 5 equipped in the storage tank 4 for temporarily storing the generated crude titanium tetrachloride liquid, and transfer pumps 8 and 12 for transferring the crude titanium tetrachloride liquid, This malfunction occurs frequently. As described above.

  Therefore, in the method for preventing adhesion of high-boiling substances in the distillation system of the present embodiment, a small amount of the circulating liquid at the top of the column that is circulated through the top of the distillation column 11 is taken out through the flow distributor 15 and the transfer pump 16 and The liquid side conduit 6 and the shaft seals of the transfer pumps 8 and 12 are pressurized and supplied. In addition, since the transfer pump 16 transfers the titanium tetrachloride liquid which does not contain the high boiling point substance after distillation, the malfunctioning by adhesion of a high boiling point substance does not arise.

  Although the tower top circulating liquid in the distiller 8 is not a product as described above, it contains almost no high-boiling substances that cause adhesion, and becomes an effective cleaning liquid for the attached high-boiling substances. A small amount of this is continuously or intermittently supplied to the liquid-side conduit 6 of the liquid level gauge 5, and the inside of the conduit 6 is always filled with a circulating liquid at the top of the column containing no high-boiling substances. By doing so, the liquid intrusion portion of the liquid level gauge 5 is sealed with a circulating liquid at the top of the tower that does not contain high-boiling substances, and malfunction due to the occurrence of deposits on the liquid level gauge 5 is prevented. When surplus of the circulating liquid at the top of the pipe 6 is produced, it flows backward to the storage tank 4, but as described above, it does not cause a quality problem.

  Further, in the transfer pumps 8 and 12, as shown in FIG. 2, the crude titanium tetrachloride liquid is sucked from the introduction pipe 18 below the central portion by the rotation of the horizontal rotary blade 17, and is discharged to the side by the discharge pipe 19. The A vertical rotary shaft 20 for driving the rotary blade 17 is driven by a motor (not shown) and is sealed with a metal seal 21 immediately above the rotary blade 17. As a seal liquid for the shaft seal portion, conventionally, a crude titanium tetrachloride liquid filtered by a filter has been supplied under pressure above the metal seal 21. The reason why the crude titanium tetrachloride liquid is used as the seal liquid is that no problem occurs even if the seal liquid is mixed into the crude titanium tetrachloride liquid as a transfer medium. Moreover, the reason why the crude titanium tetrachloride solution is subjected to filtration is to remove the solid matter in the solution and prevent malfunction. However, the result is that, as described above, it is inevitable that malfunctions frequently occur due to the intrusion of crude titanium tetrachloride liquid into the shaft seal and the deposition of high-boiling substances in the liquid. .

  Therefore, in this embodiment, in order to prevent this malfunction, the circulating liquid is continuously or intermittently used as the sealing liquid so that the tower top circulating liquid not containing the high boiling point material is always filled above the metal seal 21. A small amount is supplied. The supply pressure is a pressure at which the crude titanium tetrachloride liquid as a transfer medium does not flow into the seal portion. Thereby, the supplied circulating liquid at the top of the tower enters a slight gap between the rotary shaft 20 and the metal seal 21. As a result, adhesion and deposition of high-boiling substances in the seal portion are prevented, and malfunction due to adhesion and deposition of high-boiling substances is prevented. A part of the supplied circulating liquid at the top of the tower passes between the rotary shaft 20 and the metal seal 21 and is mixed into the crude titanium tetrachloride liquid which is a transfer medium by the rotary blades 17. As described above, there is no problem.

  Thus, in this embodiment, the differential pressure type level gauge 5 provided in the storage tank 4 for temporarily storing the generated crude titanium tetrachloride liquid, and the transfer pumps 8 and 12 for transferring the crude titanium tetrachloride liquid. In this case, malfunction due to adhesion of sticky substances is economically prevented by using the circulating liquid at the top of the system. This also eliminates the need for disassembly and maintenance, and the work and operation stop associated with the disassembly and maintenance are eliminated, improving the economic efficiency.

  The economic effect of the present invention will be clarified by comparison with a comparative example.

In the first comparison, in the differential pressure type level gauge equipped in the storage tank that temporarily stores the generated crude titanium tetrachloride liquid, it occurs due to the adhesion of high boiling point substances in the crude titanium tetrachloride liquid. Prevent malfunction. In order to prevent this, as Example 1 of the present invention, the circulating liquid at the top of the tower was supplied to the liquid-side conduit, and the inside of the conduit was always filled with the circulating fluid. As Inventive Example 2, a pure titanium tetrachloride liquid as a product was supplied. The supply amount was 1 liter / min. No malfunction occurred, and the level gauge was not required to be disassembled.

  On the other hand, as Comparative Example 1, the sealing liquid was not supplied into the liquid-side conduit, and the crude titanium tetrachloride liquid in the tank was kept flowing. In order to prevent malfunction, the inflow of the crude liquid was temporarily interrupted once every hour, and gas was blown from the liquid side conduit to the liquid level gauge. Adhesion could not be completely prevented, and it was necessary to disassemble and maintain the liquid level gauge every 30 days. As Comparative Example 2, crude titanium tetrachloride liquid filtered with a filter was supplied to the liquid side conduit, and the liquid level gauge was sealed with this liquid. In order to prevent malfunction, it was necessary to disassemble and maintain the level gauge every 30 days.

  Conventionally, the crude titanium tetrachloride liquid in the tank is allowed to flow into the liquid-side conduit (conventional example). It was necessary to disassemble and maintain the liquid level gauge every 7 days to prevent malfunction.

  In either case, the malfunction of the liquid level gauge could be prevented, and the measurement error could be suppressed within 2%. However, the cost required for preventing the malfunction is considerably higher in the comparative example than in the inventive example. The cost in each example is shown in Table 1 as 100 in the case of Comparative Example 1 by gas blow.

  In the case of the conventional example in which measures for preventing malfunction are not particularly taken, in order to prevent malfunction, disassembly and maintenance are required once every seven days, and the prevention cost increases. Even if preventive measures are taken, when gas blow or filtrate is used, disassembly and maintenance are required once every 30 days, and the prevention cost is still high. On the other hand, if the level gauge is sealed with a liquid in which high-boiling substances have been reduced by distillation, malfunctions can be prevented without disassembly and the prevention cost is greatly reduced. From the viewpoint of the liquid cost, the circulating liquid at the top is more advantageous than the product liquid.

  As the next contrast test, malfunction due to adhesion of sticky material on the shaft seal of the transfer pump is prevented. In order to prevent this, a tower top circulating liquid was used as the shaft seal liquid as Example 3 of the present invention. A product solution was used as Invention Example 4. The supply amount of the shaft seal liquid was 1 liter / min. No malfunction occurred, and the level gauge was not required to be disassembled.

  On the other hand, as Comparative Example 3, a crude titanium tetrachloride solution that was filtered into the shaft seal solution was used. This is the method originally considered by the present applicant for the purpose of preventing contamination and malfunction. The supply amount of the shaft seal liquid was set to 1 liter / minute as in the present invention examples 3 and 4. Although contamination prevention was achieved, it was necessary to disassemble and maintain the shaft seal every 30 days to prevent malfunction. The cost in each example is shown in Table 2 with the case of Comparative Example 3 being 100.

  In either case, malfunction of the transfer pump could be prevented. However, in order to prevent this, in Comparative Example 3, it is necessary to disassemble and maintain once every 30 days, which increases the prevention cost. On the other hand, in the inventive examples 3 and 4, it is possible to prevent malfunction without disassembly and maintenance, and the prevention cost is greatly reduced. From the viewpoint of the liquid cost, the circulating liquid at the top is more advantageous than the product liquid. By the way, when crude titanium tetrachloride liquid that is not filtered is used for the shaft seal, disassembly and maintenance are required once every 15 days, and the cost jumps to 200.

It is a block diagram of the titanium tetrachloride manufacturing equipment which shows one Embodiment of this invention. It is a block diagram of the shaft seal part which is the principal part of a transfer pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow reaction furnace 2 Cyclone 3, 10, 14, 22 Capacitor 4 Storage tank 5 Level gauge 6 Liquid side conduit 7 Space side conduit 8, 12, 16 Transfer pump 9 Evaporator 11 Distillation tower 13 Boiler 15 Current divider 16 Transfer pump 17 Rotating blade 18 Introduction pipe 19 Discharge pipe 20 Rotating shaft 21 Metal seal

Claims (4)

In a distillation system that distills crude titanium tetrachloride liquid containing high-boiling substances, the liquid in which high-boiling substances are reduced by distillation is continuously or intermittently applied to the part where the pre-distillation crude titanium tetrachloride liquid enters and adheres. The method for preventing the adhesion of high-boiling substances in a distillation system, characterized in that the adhesion to the portion is prevented. 2. The method for preventing adhesion of high-boiling substances in a distillation system according to claim 1, wherein the part for preventing adhesion is a differential pressure level gauge equipped in a storage tank for crude titanium tetrachloride liquid before distillation containing high-boiling substances. . The method for preventing adhesion of high-boiling substances in a distillation system according to claim 1, wherein the part for preventing adhesion is a shaft seal part in a transfer pump of crude titanium tetrachloride liquid before distillation containing high-boiling substances. The method for preventing adhesion of high-boiling substances in a distillation system according to claim 1 , wherein the distillation system is a distillation purification system of crude titanium tetrachloride liquid produced by chlorinating titanium oxide.

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