A molten salt chlorination temperature precision control method and a spraying device

Abstract

The present application relates to titanium tetrachloride production technical field, specifically to a kind of molten salt chlorination temperature precision control method and spraying device.The method includes: in molten salt chlorination furnace, setting two groups of spraying device of upper spraying pipe and lower spraying pipe, upper spraying pipe is located 6~10m above molten salt liquid level, lower spraying pipe is located 1~6m above molten salt liquid level;Upper spraying pipe fixed spraying, spraying amount is according to the required condensation flow rate of 60%~90% continuous spraying cold titanium tetrachloride of heat balance calculation;Lower spraying pipe is connected with frequency conversion circulating pump, and with chlorination furnace temperature is interlocked, and precise spraying is implemented.The method can be used to control the temperature of molten salt chlorination furnace within ±5℃.The present application has the advantages of simple operation, high temperature control precision, strong stability, etc., and can be widely applied in titanium tetrachloride manufacturing enterprises, with good application prospect.

Description

Technical Field

[0001] This invention relates to the field of titanium tetrachloride production technology, specifically to a method for precise control of molten salt chlorination temperature and a spraying device. Background Technology

[0002] Molten salt chlorination is one of the mainstream technologies for the industrial production of titanium tetrachloride, offering advantages such as strong raw material adaptability and a stable reaction system. The Panxi region of my country possesses extremely rich titanium resources, but the titanium raw materials have high calcium and magnesium impurity content (CaO+MgO>5%), making them unsuitable for the stringent requirements of the fluidized bed chlorination process. Molten salt chlorination can effectively process titanium slag raw materials with slightly lower TiO2 grade and higher calcium and magnesium impurity content, thus becoming the most effective method for the efficient development and utilization of high-calcium and magnesium titanium resources in the Panxi region of my country. Currently, most existing technologies employ molten salt chlorination for the industrial production of titanium tetrachloride.

[0003] Molten salt chlorination is a complex reaction process involving a mixture of gas, liquid, and solid phases. The reaction temperature is a core parameter affecting the yield, product quality, and system operational safety of titanium tetrachloride. Related studies indicate that the suitable temperature range for molten salt chlorination is typically 700–900℃. Excessive temperature fluctuations can lead to a series of problems: excessively high temperatures can cause a surge in molten salt volatilization, exacerbating equipment corrosion and raw material loss. It also promotes the volatilization of impurities such as Fe and Al, increasing the impurity content in crude titanium tetrachloride and increasing the burden on subsequent refining processes. Conversely, excessively low temperatures reduce the chlorination reaction rate, leading to a decrease in titanium slag conversion. Unreacted raw material accumulation can cause molten salt agglomeration, pipeline blockage, and other malfunctions. In severe cases, system shutdown for cleaning is necessary, resulting in decreased titanium recovery rate, increased energy consumption, and increased costs. Furthermore, the proper control of molten salt temperature and dust collection chamber temperature directly affects the content of solid impurities in crude titanium tetrachloride. When the molten salt temperature is controlled between 740 and 780°C, high-boiling-point chloride impurities such as FeCl2, MnCl2, MgCl2, CaC2, and CrCl3 are solidified inside the molten salt and carried out through waste salt discharge. Meanwhile, low-boiling-point impurities such as VOCl3, SiCl4, AlCl3, and FeCl3 enter the dust collection system with TiCl4 and require refining removal. Therefore, precise control of the molten salt temperature has a decisive impact on product quality and system operational stability.

[0004] Currently, various methods for controlling the temperature of molten salt chlorination have been developed in the industry. CN116040678A discloses a method for large-scale molten salt chlorination to produce titanium tetrachloride, which uses slurry washing for spray temperature control. The spray positions are located at the top and middle of the chlorination furnace, and the spray volume is adjusted in real time by a DCS system based on the top and middle temperatures. The temperature in the middle of the chlorination furnace can be controlled at 750±5℃. However, this scheme has significant shortcomings: the spray medium is coarse titanium tetrachloride slurry containing solid impurities, which are prone to deposit in the furnace. Long-term operation can lead to blockage of system pipelines and a decrease in heat transfer efficiency. Furthermore, the use of a DCS system for overall linkage regulation of multiple spray points lacks independent control capability between each spray point, resulting in a lag in temperature response and making it difficult to achieve precise independent control of the furnace temperature. CN121020643A discloses a method for dynamic control of molten salt temperature in a molten salt chlorination furnace. Based on the deviation between the real-time molten salt temperature and the preset reference temperature, it dynamically adjusts the return flow rate of liquid titanium tetrachloride slurry and the discharge flow rate of waste molten salt. However, it only involves the flow rate adjustment of a single spray channel and does not involve setting multiple spray devices at different heights above the molten salt surface to achieve layered independent control. CN107963653B discloses a gradient control method for the temperature of a molten salt chlorination system. It achieves system-level temperature gradient control by controlling the temperature at multiple points such as the chlorination furnace outlet and the dust collector. However, its core lies in the temperature gradient management of the entire chlorination system, rather than focusing on the precise temperature control of the molten salt chlorination furnace itself, and it does not involve a layered control scheme for multiple spray devices in the furnace. The academic paper "Research on Thermal Balance Control in the Preparation of Crude TiCl4 by Molten Salt Chlorination" reports that the molten salt temperature is controlled at 740-770℃ by adjusting the amount of return slurry. However, this study only involves the overall adjustment of the total amount of return slurry and does not disclose a technical scheme for layered independent control of multiple spray points. Other studies have shown that the heat flux density and temperature gradient of the molten salt chlorination furnace indicate that the heat transfer from the furnace wall has a relatively small impact on the steady-state temperature field, while the spraying of titanium tetrachloride slurry is the biggest factor affecting the steady-state temperature field of the chlorination furnace. This further illustrates that optimizing the spraying control strategy is crucial for precise temperature control.

[0005] Existing methods generally suffer from the following core technical bottlenecks: ① Low temperature control accuracy and slow response. External temperature control methods have low heat transfer efficiency and cannot quickly respond to drastic changes in the heat of reaction within the furnace. Production practice data shows that the temperature fluctuation range of molten salt chlorination in existing processes is mostly between 50 and 100°C, which is insufficient to meet the precise temperature control requirements of high-end titanium tetrachloride production. ② Single control methods easily disrupt the equilibrium of the reaction system. Adjusting only a single variable such as chlorine flow rate or feed rate often leads to unintended consequences, resulting in increased temperature fluctuations and affecting the chemical equilibrium of the reaction. ③ Lack of a precise control mechanism linked to the reaction process. Existing solutions are mostly open-loop or semi-closed-loop controls, which cannot achieve dynamic and stable temperature control and are difficult to adapt to production disturbances such as fluctuations in raw material grade and changes in chlorine concentration. ④ High solids content in the spray medium, easily causing system failures. When using rinsing slurry (coarse titanium tetrachloride slurry) as the spray medium, solid impurities accumulate in the furnace and pipelines, leading to dust collector blockage, unstable system pressure, and in severe cases, requiring system shutdown for cleaning. Although molten salt chlorination can process materials that boiling chlorination cannot handle, it is difficult to control, and existing technologies have not yet been able to solve the problem of precise and stable temperature control in molten salt chlorination furnaces.

[0006] To address the aforementioned issues, the industry urgently needs a temperature control method that offers rapid response, precise temperature control, and seamless integration with the reaction system. Based on this, this invention proposes a technical solution employing a dual-set recooled titanium tetrachloride spray device for coordinated control. This solution utilizes the sensible and latent heat exchange of cold titanium tetrachloride to achieve rapid temperature control, while a chain-link control mechanism ensures precise temperature control. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical shortcomings of existing molten salt chlorination temperature control methods, such as low temperature control accuracy, slow response, and easy disruption of reaction equilibrium, and to provide a precise temperature control method for molten salt chlorination. By setting up two sets of high- and low-temperature recirculating titanium tetrachloride spray devices, combined with a coordinated mode of fixed spraying and interlocking precise spraying, stable temperature control of the molten salt chlorination furnace within ±5℃ is achieved, ensuring reaction efficiency and product quality, and improving system operational stability. To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for controlling the chlorination temperature of molten salt includes the following steps: An upper spray pipe and a lower spray pipe at different heights are installed inside the molten salt chlorination furnace. The lower spray pipe is located above the molten salt surface and below the upper spray pipe. The upper spray pipe is controlled to operate in a fixed spray volume mode to continuously spray cold titanium tetrachloride into the furnace. The real-time temperature inside the molten salt chlorination furnace is obtained, and the lower spray pipe is controlled to operate in a variable spray volume mode according to the real-time temperature. The temperature of the molten salt chlorination furnace is controlled by adjusting the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe.

[0008] Furthermore, when the lower spray pipe is operated in a variable spray volume mode according to the real-time temperature, if the real-time temperature is higher than the set upper temperature limit, the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe is increased; if the real-time temperature is lower than the set lower temperature limit, the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe is decreased or the spraying of the lower spray pipe is stopped.

[0009] Furthermore, the fixed spray volume of the upper spray pipe is set to 60% to 90% of the condensate reflux flow rate required for the heat balance calculation of the molten salt chlorination furnace. This setting can utilize the heat exchange between cold titanium tetrachloride and the high-temperature flue gas in the furnace to achieve basic control of the reaction temperature. At the same time, the sprayed cold titanium tetrachloride can capture some of the molten salt droplets and fine particulate impurities in the flue gas, thus also having an auxiliary impurity removal function.

[0010] Furthermore, the temperature of the cold titanium tetrachloride is 40~60℃.

[0011] Furthermore, the lower spray pipe is located 1-6m above the molten salt surface, and the upper spray pipe is located 6-10m above the molten salt surface.

[0012] A molten salt chlorination temperature control spray device for implementing the above-mentioned molten salt chlorination temperature control method includes: Molten salt chlorination furnace; The upper spray pipe is installed inside the molten salt chlorination furnace and located above the molten salt surface, for continuously spraying cold titanium tetrachloride in a fixed spray volume mode; The lower spray pipe is installed inside the molten salt chlorination furnace, located above the molten salt surface and below the upper spray pipe, and is used to spray cold titanium tetrachloride in a variable spray volume mode. A variable frequency circulating pump, connected to the lower spray pipe, is used to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe; The temperature control unit is connected to the variable frequency circulating pump via a signal connection. A temperature detection device is installed inside the molten salt chlorination furnace and is signal-connected to the temperature control unit. It is used to acquire the real-time temperature inside the molten salt chlorination furnace and transmit it to the temperature control unit. The temperature control unit, the variable frequency circulating pump, and the temperature detection device form an interlocked control loop. The temperature control unit controls the operating frequency of the variable frequency circulating pump through the interlocked control loop according to the real-time temperature, so as to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe or stop the spraying of the lower spray pipe.

[0013] Furthermore, the lower spray pipe is located 1-6m above the molten salt surface, and the upper spray pipe is located 6-10m above the molten salt surface.

[0014] Furthermore, both the upper and lower spray pipes are annular spray pipes, arranged circumferentially along the molten salt chlorination furnace.

[0015] Furthermore, the diameter of the upper and lower spray pipes is 2-3m.

[0016] Furthermore, the upper spray pipe and the lower spray pipe are each provided with a plurality of spray holes, which are evenly distributed along the length of the spray pipe.

[0017] Furthermore, the diameter of the spray holes is 4~10mm, and the distance between adjacent spray holes is 100~500mm.

[0018] Furthermore, the temperature detection device includes multiple K-type thermocouples, which are evenly distributed along the circumference of the molten salt chlorination furnace and are used to detect the temperature at different locations within the molten salt chlorination furnace. The temperature control unit controls the operating frequency of the variable frequency circulating pump based on the weighted average or median value of the multiple K-type thermocouple readings.

[0019] Furthermore, an electromagnetic flow meter is installed on the upper spray pipe and / or the lower spray pipe to accurately measure the spray volume of cold titanium tetrachloride sprayed by the spray pipe.

[0020] By adopting the above technical solution, the present invention has at least the following advantages and beneficial effects: (1) High temperature control accuracy and fast response: The present invention adopts a dual-set spray device for coordinated control. The upper spray achieves basic temperature control, and the lower spray achieves dynamic and precise return through a chain mechanism. It utilizes cold titanium tetrachloride to directly exchange heat with the high-temperature system in the furnace. The heat exchange efficiency is significantly improved compared with the external temperature control method. The molten salt chlorination temperature can be stably controlled within ±5℃, which is far superior to the temperature control accuracy of the existing process, effectively ensuring the reaction stability and product quality.

[0021] (2) Simple operation and strong adaptability: The spraying device of the present invention can be directly modified and installed on the basis of the existing molten salt chlorination furnace without the need to reconstruct the reaction system; the spraying medium uses cold titanium tetrachloride recovered in the production process to realize resource recycling and no additional impurities are introduced; the method can be adapted to molten salt chlorination furnaces with different production capacities, and titanium slag of different grades also has good adaptability, which is convenient for existing enterprises to quickly promote and apply.

[0022] (3) Improve system stability and reduce production costs: Precise temperature control can avoid molten salt volatilization, raw material loss and equipment corrosion caused by temperature fluctuations, and reduce raw material consumption and equipment maintenance costs; at the same time, it can improve the titanium slag conversion rate, reduce the failure shutdown caused by unreacted raw material accumulation, and extend the continuous operation cycle of the equipment; in addition, the recycling of the spraying medium can reduce titanium tetrachloride loss, which has significant economic benefits.

[0023] (4) It also has the function of auxiliary impurity removal: the cold titanium tetrachloride continuously sprayed by the upper spray device can fully contact the high temperature flue gas in the furnace, capture the molten salt droplets and solid fine particles entrained in the flue gas, further reduce the content of crude titanium tetrachloride solid phase, and has the additional advantage of improving product quality.

[0024] Overall, through the coordinated control of the upper and lower spray devices, the reaction temperature in the molten salt chlorination furnace is stably controlled within ±5℃ of the set target value. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0026] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0028] In this embodiment of the invention: A molten salt chlorination temperature control spray device for implementing a molten salt chlorination temperature control method includes the following structure: Molten salt chlorination furnace; The upper spray pipe is installed inside the molten salt chlorination furnace and located above the molten salt surface, for continuously spraying cold titanium tetrachloride in a fixed spray volume mode; The lower spray pipe is installed inside the molten salt chlorination furnace, located above the molten salt surface and below the upper spray pipe, and is used to spray cold titanium tetrachloride in a variable spray volume mode. A variable frequency circulating pump, connected to the lower spray pipe, is used to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe; The temperature control unit is connected to the variable frequency circulating pump via a signal connection. A temperature detection device is installed inside the molten salt chlorination furnace and is signal-connected to the temperature control unit. It is used to acquire the real-time temperature inside the molten salt chlorination furnace and transmit it to the temperature control unit. The temperature control unit, the variable frequency circulating pump, and the temperature detection device form an interlocked control loop. The temperature control unit controls the operating frequency of the variable frequency circulating pump through the interlocked control loop according to the real-time temperature, so as to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe or stop the spraying of the lower spray pipe.

[0029] Furthermore, the lower spray pipe is located 1-6m above the molten salt surface, and the upper spray pipe is located 6-10m above the molten salt surface.

[0030] Furthermore, both the upper and lower spray pipes are annular spray pipes, arranged circumferentially along the molten salt chlorination furnace.

[0031] Furthermore, the diameter of the upper and lower spray pipes is 2-3m.

[0032] Furthermore, the upper spray pipe and the lower spray pipe are each provided with a plurality of spray holes, which are evenly distributed along the length of the spray pipe.

[0033] Furthermore, the diameter of the spray holes is 4~10mm, and the distance between adjacent spray holes is 100~500mm.

[0034] Furthermore, the temperature detection device includes multiple K-type thermocouples, which are evenly distributed along the circumference of the molten salt chlorination furnace and are used to detect the temperature at different locations within the molten salt chlorination furnace. The temperature control unit controls the operating frequency of the variable frequency circulating pump based on the weighted average or median value of the multiple K-type thermocouple readings.

[0035] Furthermore, an electromagnetic flow meter is installed on the upper spray pipe and / or the lower spray pipe to accurately measure the spray volume of cold titanium tetrachloride sprayed by the spray pipe.

[0036] The fixed spray volume of the upper spray pipe is set to 60% to 90% of the condensation return flow required by the heat balance calculation of the molten salt chlorination furnace.

[0037] The titanium slag uses high-calcium magnesium titanium slag with a TiO2 grade of approximately 74% produced by Panzhihua Iron and Steel Group Titanium Smelting Plant as the main raw material. The content of each component is as follows (%): TiO2 74.60, Al2O3 1.63, CaO 1.69, MgO 4.67, MnO 1.20, V2O5 0.15, FeO 7.20, SiO2 4.50, with the balance being unavoidable impurities.

[0038] The petroleum coke is calcined petroleum coke (fixed carbon 98.45%, ash 0.36%, volatile matter 0.40%, moisture 0.07%).

[0039] The sodium chloride content is approximately 98%. Chlorine content ≥99.5%.

[0040] Example 1: (1) Equipment and raw material preparation: Two sets of recooled titanium tetrachloride spraying devices are set up in the molten salt chlorination furnace, with the upper spray pipe 6m away from the molten salt level and the lower spray pipe 1m away from the molten salt level; both sets of spraying devices are annular pipes (2m in diameter), with spray holes of 5mm in diameter evenly opened on the pipe body (hole spacing 150mm); the lower spray pipe is connected to a variable frequency circulating pump, and three evenly distributed K-type thermocouples are installed in the furnace to form an interlocked control loop with the temperature control unit and the variable frequency circulating pump. Titanium slag, petroleum coke and sodium chloride are thoroughly mixed, and the spraying medium is cold titanium tetrachloride cooled to 50℃.

[0041] (2) Basic parameter settings: The target reaction temperature for molten salt chlorination is 750℃. The required condensation return flow rate for heat balance under this capacity is obtained through heat balance calculation. The spray rate of the upper spray device is set to 60% of the required condensation return flow rate for heat balance, and continuous fixed spraying is maintained. The temperature trigger threshold is set to ±3℃, that is, when the temperature is ≥753℃ or ≤747℃, the lower spray device is triggered for interlocking control.

[0042] (3) Chlorination reaction and temperature control: The mixed raw materials are added to the chlorination furnace and chlorine gas is introduced to carry out the chlorination reaction; the upper spray device continuously sprays 50°C cold titanium tetrachloride; when the thermocouple detects that the temperature inside the furnace rises to 754°C, the control system triggers the start of the variable frequency circulating pump, and the lower spray device sprays cold titanium tetrachloride. After 3 minutes, the temperature returns to 750°C, and the variable frequency circulating pump stops spraying; the temperature fluctuation range during the reaction is stable within 748~752°C, that is, within ±2°C.

[0043] Example 2: (1) Equipment and raw material preparation: Two sets of recooled titanium tetrachloride spraying devices are set up in the molten salt chlorination furnace, one high and one low. The upper spraying pipe is 8m away from the molten salt level, and the lower spraying pipe is 4m away from the molten salt level. Both sets of spraying devices are annular pipes (diameter 2.5m), with spray holes of 6mm diameter evenly opened on the pipe body (hole spacing 300mm). The lower spraying pipe is connected to a variable frequency circulating pump. Four evenly distributed K-type thermocouples are installed in the furnace to form an interlocking control loop with the temperature control unit and the variable frequency circulating pump. Titanium slag, petroleum coke and sodium chloride are thoroughly mixed, and the spraying medium is cold titanium tetrachloride cooled to 45℃.

[0044] (2) Basic parameter setting: The target reaction temperature of molten salt chlorination is 780℃. The required condensation return flow rate for heat balance under this capacity is obtained through heat balance calculation. The spraying volume of the upper spray device is set to 80% of the required condensation return flow rate for heat balance, and continuous fixed spraying is maintained. The temperature trigger threshold is set to ±3℃, that is, when the temperature is ≥783℃ or ≤777℃, the lower spray device is triggered for interlocking control.

[0045] (3) Chlorination reaction and temperature control: The mixed raw materials are added to the chlorination furnace through the feeding port, and chlorine gas is introduced to carry out the chlorination reaction; the upper spray device continuously sprays 45°C cold titanium tetrachloride; when the thermocouple detects that the temperature inside the furnace drops to 776°C, the control system triggers the start of the variable frequency circulating pump, and the lower spray device sprays cold titanium tetrachloride. After 2 minutes, the temperature rises back to 780°C, and the variable frequency circulating pump stops spraying; the temperature fluctuation range during the reaction is stable within 777~783°C, that is, within ±3°C.

[0046] Example 3: (1) Equipment and raw material preparation: Two sets of recooled titanium tetrachloride spraying devices are set up in the molten salt chlorination furnace, with the upper spray pipe 10m away from the molten salt level and the lower spray pipe 6m away from the molten salt level; both sets of spraying devices are annular pipes (3m in diameter), with spray holes of 8mm in diameter evenly opened on the pipe body (hole spacing 500mm); the lower spray pipe is connected to a dual variable frequency circulating pump (one for use and one for standby), and 6 evenly distributed K-type thermocouples are installed in the furnace to form a redundant interlocking control loop with the temperature control unit and the variable frequency circulating pump. Titanium slag, petroleum coke and sodium chloride are thoroughly mixed, and the spraying medium is cold titanium tetrachloride cooled to 55℃.

[0047] (2) Basic parameter setting: The target reaction temperature of molten salt chlorination is 820℃. The required condensation return flow rate for heat balance under this production capacity is obtained through heat balance calculation. The spraying volume of the upper spray device is set to 90% of the required condensation return flow rate, and continuous fixed spraying is maintained. The temperature trigger threshold is set to ±3℃, that is, when the temperature is ≥823℃ or ≤817℃, the lower spray device is triggered for interlocking control.

[0048] (3) Chlorination reaction and temperature control: The mixed raw materials are added to the chlorination furnace through the feeding port, and chlorine gas is introduced to carry out the chlorination reaction; the upper spray device continuously sprays 55°C cold titanium tetrachloride; when the thermocouple detects that the temperature inside the furnace rises to 824°C, the control system triggers the start of the variable frequency circulating pump, and the lower spray device sprays cold titanium tetrachloride. After 4 minutes, the temperature returns to 820°C, and the variable frequency circulating pump stops spraying; during the reaction, there are multiple temperature fluctuation trends, which are all quickly restored by precise control of the lower spray device. The overall temperature fluctuation range is stable within 817~823°C, that is, within ±3°C.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for controlling the chlorination temperature of molten salt, characterized in that, Includes the following steps: An upper spray pipe and a lower spray pipe at different heights are installed inside the molten salt chlorination furnace. The lower spray pipe is located above the molten salt surface and below the upper spray pipe. The upper spray pipe is controlled to operate in a fixed spray volume mode to continuously spray cold titanium tetrachloride into the furnace. The real-time temperature inside the molten salt chlorination furnace is obtained, and the lower spray pipe is controlled to operate in a variable spray volume mode according to the real-time temperature. The temperature of the molten salt chlorination furnace is controlled by adjusting the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe.

2. The method for controlling the molten salt chlorination temperature according to claim 1, characterized in that, When the lower spray pipe is controlled to operate in a variable spray volume mode according to the real-time temperature, when the real-time temperature is higher than the set upper temperature limit, the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe is increased; when the real-time temperature is lower than the set lower temperature limit, the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe is decreased or the spraying of the lower spray pipe is stopped.

3. The method for controlling the chlorination temperature of molten salt according to claim 1, characterized in that, The fixed spray volume of the upper spray pipe is set to 60% to 90% of the condensation return flow required by the heat balance calculation of the molten salt chlorination furnace.

4. The method for controlling the molten salt chlorination temperature according to claim 1, characterized in that, The temperature of the cold titanium tetrachloride is 40~60℃.

5. The method for controlling the chlorination temperature of molten salt according to claim 1, characterized in that, The lower spray pipe is located 1-6m above the molten salt surface, and the upper spray pipe is located 6-10m above the molten salt surface.

6. A molten salt chlorination temperature-controlled spraying device for implementing the method according to any one of claims 1-5, characterized in that, include: Molten salt chlorination furnace; The upper spray pipe is installed inside the molten salt chlorination furnace and located above the molten salt surface, for continuously spraying cold titanium tetrachloride in a fixed spray volume mode; The lower spray pipe is installed inside the molten salt chlorination furnace, located above the molten salt surface and below the upper spray pipe, and is used to spray cold titanium tetrachloride in a variable spray volume mode. A variable frequency circulating pump, connected to the lower spray pipe, is used to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe; The temperature control unit is connected to the variable frequency circulating pump via a signal connection. A temperature detection device is installed inside the molten salt chlorination furnace and is signal-connected to the temperature control unit. It is used to acquire the real-time temperature inside the molten salt chlorination furnace and transmit it to the temperature control unit. The temperature control unit, the variable frequency circulating pump, and the temperature detection device form an interlocked control loop. The temperature control unit controls the operating frequency of the variable frequency circulating pump through the interlocked control loop according to the real-time temperature, so as to adjust the spray volume of cold titanium tetrachloride sprayed by the lower spray pipe or stop the spraying of the lower spray pipe.

7. The molten salt chlorination temperature-controlled spraying device according to claim 6, characterized in that, Both the upper and lower spray pipes are annular spray pipes, arranged circumferentially along the molten salt chlorination furnace.

8. The molten salt chlorination temperature-controlled spraying device according to claim 6, characterized in that, The upper and lower spray pipes are each provided with a plurality of spray holes, which are evenly distributed along the length of the spray pipes.

9. The molten salt chlorination temperature-controlled spraying device according to claim 6, characterized in that, The temperature detection device includes multiple K-type thermocouples, which are evenly distributed around the circumference of the molten salt chlorination furnace and are used to detect the temperature at different locations within the molten salt chlorination furnace. The temperature control unit controls the operating frequency of the variable frequency circulating pump based on the weighted average or median value of the multiple K-type thermocouple readings.

10. The molten salt chlorination temperature-controlled spraying device according to claim 6, characterized in that, Electromagnetic flow meters are installed on the upper spray pipe and / or the lower spray pipe to accurately measure the spray volume of cold titanium tetrachloride.