A circulating chlorine gas treatment system and method for a molten salt chlorination furnace

Abstract

The present application relates to the field of chlorination metallurgy, and proposes a circulating chlorine treatment system and method for a molten salt chlorination furnace, which comprises: a chlorine buffer tank, a chlorination furnace body, and a chlorine pipeline connecting the two; wherein the chlorine buffer tank, the chlorine pipeline, and the chlorination furnace body are sequentially connected, an ultrasonic agglomeration device is arranged at the gas inlet of the chlorine buffer tank, and the ultrasonic agglomeration device is used for agglomerating titanium dioxide particles entrained in the circulating chlorine gas entering from the gas inlet; at least one set of horizontal baffles is arranged on the inside of the chlorine buffer tank on the gas flow path, and the horizontal baffles are used for promoting the settlement of the agglomerated particles; the chlorine pipeline is connected to a tangential downward inlet on the side wall of the chlorination furnace body, the included angle between the tangential direction of the tangential downward inlet and the horizontal direction is 5-22°, and the circulating chlorine gas enters the chlorination furnace body in a cyclone manner. The present application guarantees the economy and continuity of the titanium dioxide oxidation and molten salt chlorination process.

Description

Technical Field

[0001] This invention relates to the field of chlorination metallurgy, and more particularly to a circulating chlorine gas treatment system and method for a molten salt chlorination furnace. Background Technology

[0002] High-quality titanium tetrachloride is an important industrial raw material for the production of sponge titanium and titanium dioxide. Molten salt chlorination is widely used due to its good adaptability to low-grade titanium-containing materials. In existing technologies, when the titanium dioxide oxidation process is combined with the molten salt chlorination process, the circulating chlorine gas after collecting titanium dioxide in the oxidation process contains 60-90% Cl2, which can be used as the raw material gas for the molten salt chlorination process. However, the utilization of this circulating chlorine gas faces three key technical problems: First, due to the process control of the upstream oxidation process, the Cl2 concentration in the circulating chlorine gas is low and fluctuates greatly. When the chlorine concentration is below 75%, the efficiency of the molten salt chlorination chemical reaction and the chlorine utilization rate will be significantly reduced, affecting the normal reaction and operation of the chlorination furnace. Second, the circulating chlorine gas carries residual rutile TiO2 particles, which can easily cause blockage of the chlorine gas inlet pipe. Third, rutile TiO2 is difficult to effectively chlorinate in the molten salt chlorination reaction environment, which will interfere with the normal judgment of the chlorination furnace reaction. Although the above problems can be solved by liquefying and then regasifying chlorine, this method will significantly increase production costs.

[0003] Therefore, there is an urgent need for a technical solution that can economically and effectively treat low-concentration, dust-containing circulating chlorine gas. Summary of the Invention

[0004] In view of the lack of a technical solution in the existing technology for economically and effectively treating low-concentration, dust-containing circulating chlorine gas, the present invention provides a circulating chlorine gas treatment system and method for molten salt chlorination furnaces to ensure the stable operation of molten salt chlorination furnaces and achieve effective integration of titanium dioxide oxidation and chlorination processes.

[0005] According to a first aspect of the present invention, the present invention provides a circulating chlorine treatment system for a molten salt chlorination furnace, comprising a chlorine buffer tank, a chlorination furnace body and a chlorine pipeline connecting the two.

[0006] The chlorine buffer tank is equipped with an ultrasonic agglomeration device at the gas inlet, which is used to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas introduced from the gas inlet.

[0007] The chlorine buffer tank has at least one set of horizontal baffles inside the gas flow path, which are used to promote the settling of agglomerated particles.

[0008] The chlorine pipeline is connected to a tangentially lower inlet on the side wall of the chlorination furnace body. The tangential direction of the tangentially lower inlet makes an angle of 5-22° with the horizontal direction, which is used to allow the circulating chlorine gas to enter the chlorination furnace body in a swirling manner.

[0009] In some embodiments, the gas inlet of the chlorine buffer tank is located at a height of 500-1000 mm above the bottom of the tank, and the gas outlet of the chlorine buffer tank is located at the top of the tank and connected to the chlorine pipeline.

[0010] In some embodiments, the number of horizontal baffles is 2-5, and the horizontal baffles are arranged obliquely downwards and form an angle of 1-5° with the horizontal plane.

[0011] In some embodiments, the angle between the tangential direction of the tangentially downward inlet and the horizontal direction is 5-15°.

[0012] In some embodiments, the projection of the axis of the tangentially lower inlet onto the horizontal plane is such that the angle between the projection and the circumferential tangent of the chlorination furnace body at the tangentially lower inlet is 20-40°.

[0013] In some embodiments, the system further includes an online chlorine concentration detection device and a molten salt level control device. The online chlorine concentration detection device is installed on the chlorine pipeline and is used to detect the chlorine concentration in the circulating chlorine in real time. The molten salt level control device is interlocked with the online chlorine concentration detection device and is used to dynamically adjust the molten salt level in the chlorination furnace body according to the detected chlorine concentration.

[0014] In some embodiments, when the online chlorine concentration detection device detects a 1 percentage point decrease in the volume concentration of the circulating chlorine, the molten salt level control device is set to increase the molten salt level by 0.05-0.15m.

[0015] In some embodiments, the chlorination furnace body includes a waste salt discharge port on the side wall and a flue gas outlet at the top. The height of the waste salt discharge port is 5-6.5m, and the height of the molten salt level inside the chlorination furnace body is 5-7.5m.

[0016] In some embodiments, the capacity load of the chlorination furnace body is in the range of 220-320 t / d.

[0017] According to a second aspect of the present invention, the present invention also provides a method for treating circulating chlorine gas using the system described in any of the preceding claims, comprising:

[0018] Step a: Introduce circulating chlorine gas into the chlorine buffer tank through the gas inlet.

[0019] Step b: Turn on the ultrasonic agglomeration device to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas.

[0020] Step c: Pass the circulating chlorine gas carrying agglomerated particles through the horizontal baffle to promote the settling of the agglomerated particles;

[0021] Step d: The purified circulating chlorine gas is introduced into the main body of the chlorination furnace through the tangentially downward inlet in a swirling manner;

[0022] Step e: Control the residence time of the purified circulating chlorine gas in the main body of the chlorination furnace to be 5-20 seconds.

[0023] The aforementioned circulating chlorine treatment system for molten salt chlorination furnaces, through its integrated design, achieves economical and efficient treatment of low-concentration, dust-containing circulating chlorine gas. This avoids the high costs of chlorine liquefaction and regasification purification, ensuring the economic efficiency and continuity of the titanium dioxide oxidation and molten salt chlorination processes. Specifically, by incorporating an ultrasonic agglomeration device, nano- to micron-sized rutile TiO2 particles entrained in the circulating chlorine gas are actively agglomerated, increasing the particle size and laying the foundation for subsequent efficient separation. This effectively solves the problem of tail gas dust clogging the chlorine inlet pipe and interfering with the chlorination furnace reaction judgment. By setting at least one set of horizontal baffles along the gas flow path, working in conjunction with the ultrasonic agglomeration device, the agglomerated titanium dioxide particles are fully settled in the buffer tank due to deceleration and collision, thus deeply purifying the gas. This significantly reduces the dust content entering subsequent pipes with the gas, further ensuring unobstructed pipe flow and preventing ineffective materials from entering the reaction zone. By connecting the chlorine inlet pipe to a tangentially lower inlet on the side wall of the chlorination furnace body, and limiting the angle between its tangential direction and the horizontal direction to 5-22°, the purified circulating chlorine gas enters the molten pool inside the chlorination furnace body in a swirling manner. This gas intake method has multiple advantages: First, it effectively reduces the direct impact of gas on the molten pool surface, reducing energy loss; second, the swirling flow extends the movement path of bubbles in the molten pool, thus significantly increasing the reaction contact time between low-concentration chlorine gas and the solid materials in the molten pool; third, it promotes bubble breakage and uniform distribution, enhancing the mixing efficiency of the gas-liquid-solid three-phase system. This effectively solves the technical problem of reduced molten salt chlorination chemical reaction efficiency and chlorine utilization rate when the chlorine concentration decreases. By optimizing fluid dynamics to compensate for the weakened reaction driving force caused by the reduced concentration, it ensures that even when the circulating chlorine gas concentration fluctuates within the range of 60-90%, the chlorination furnace can still maintain efficient and stable reaction operation.

[0024] In addition, a circulating chlorine gas treatment method for a molten salt chlorination furnace according to this application can also achieve the above-mentioned technical effects, which will not be elaborated here. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of a circulating chlorine gas treatment system for a molten salt chlorination furnace provided in one embodiment of the present invention;

[0027] Figure 2 A cross-sectional schematic diagram of the chlorination furnace body provided in another embodiment of the present invention;

[0028] Figure 3 A flowchart of a circulating chlorine gas treatment method for a molten salt chlorination furnace, provided as another embodiment of the present invention;

[0029] The attached figures are labeled as follows:

[0030] 1. Chlorine buffer tank; 2. Chlorination furnace body; 3. Chlorine pipeline; 11. Gas inlet; 12. Ultrasonic agglomeration device; 13. Horizontal baffle; 14. Gas outlet; 21. Tangentially downward inlet; 22. Waste salt discharge port; 23. Flue gas outlet; 100. Circulating chlorine treatment system for molten salt chlorination furnace. Detailed Implementation

[0031] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0032] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0033] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Terms such as "including" or "contains" mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility of covering other elements as well.

[0034] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0036] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0037] According to the first aspect of the invention, please refer to Figure 1-2 , Figure 1 This invention provides a schematic diagram of a circulating chlorine gas treatment system for a molten salt chlorination furnace. Figure 2 This is a cross-sectional schematic diagram of the main body of a chlorination furnace provided in another embodiment of the present invention, used to process circulating chlorine gas with a chlorine volume concentration of 60-90% from the titanium dioxide oxidation unit, such as... Figure 1 As shown, the circulating chlorine treatment system 100 includes: a chlorine buffer tank 1, a chlorination furnace body 2, and a chlorine pipeline 3 connecting the two; wherein, the chlorine buffer tank 1, the chlorine pipeline 3, and the chlorination furnace body 2 are connected in sequence, and an ultrasonic agglomeration device 12 is provided at the gas inlet 11 of the chlorine buffer tank 1, which is used to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas introduced from the gas inlet 11; at least one set of horizontal baffles 13 are provided inside the chlorine buffer tank 1 in the gas flow path, which is used to promote the settling of agglomerated particles; the chlorine pipeline 3 is connected to a tangentially lower inlet 21 on the side wall of the chlorination furnace body 2, and the tangential direction of the tangentially lower inlet 21 makes an angle of 5-22° with the horizontal direction, which is used to allow the circulating chlorine gas to enter the molten pool in the chlorination furnace body 2 in a swirling manner.

[0038] In some embodiments, the circulating chlorine gas from the titanium dioxide oxidation unit, with a chlorine volume concentration fluctuating between 60% and 90%, and containing rutile TiO2 particles at the nano to micron scale, first enters the chlorine buffer tank 1 for pretreatment to remove most of the dust, and then is guided to the chlorination furnace body 2 via the chlorination pipeline 3 to participate in the chlorination reaction.

[0039] The aforementioned circulating chlorine treatment system 100 for molten salt chlorination furnaces, through its integrated design, achieves economical and effective treatment of low-concentration, dust-containing circulating chlorine gas. This avoids the high costs of chlorine liquefaction and regasification purification, ensuring the economic efficiency and continuity of the titanium dioxide oxidation and molten salt chlorination processes. Specifically, by incorporating an ultrasonic agglomeration device 12, nano- to micron-sized rutile TiO2 particles entrained in the circulating chlorine gas are actively agglomerated, increasing the particle size and laying the foundation for subsequent efficient separation. This effectively solves the problem of tail gas dust causing blockage in the chlorine inlet pipe and interfering with the chlorination furnace reaction judgment. By setting at least one set of horizontal baffles 13 along the gas flow path, working in conjunction with the ultrasonic agglomeration device 12, the agglomerated titanium dioxide particles are fully settled in the buffer tank due to deceleration and collision, thereby deeply purifying the gas. This significantly reduces the dust content entering subsequent pipes with the gas, further ensuring unobstructed pipe flow and preventing ineffective materials from entering the reaction zone. By connecting the chlorine inlet 3 to the tangentially lower inlet 21 on the side wall of the chlorination furnace body 2, and limiting the angle between its tangential direction and the horizontal direction to 5-22°, the purified circulating chlorine gas enters the molten pool inside the chlorination furnace body 2 in a swirling manner. This gas intake method has multiple advantages: First, it effectively reduces the direct impact of gas on the molten pool surface, reducing energy loss; second, the swirling flow can prolong the movement path of bubbles in the molten pool, thereby significantly increasing the reaction contact time between low-concentration chlorine gas and the solid materials in the molten pool; third, it promotes the breakup and uniform distribution of bubbles, enhancing the mixing efficiency of the gas-liquid-solid three phases. This effectively solves the technical problem of reduced molten salt chlorination chemical reaction efficiency and chlorine utilization rate when the chlorine concentration decreases. By optimizing fluid dynamics to compensate for the weakened reaction driving force caused by the reduced concentration, it ensures that even when the circulating chlorine gas concentration fluctuates within the range of 60-90%, the chlorination furnace can still maintain efficient and stable reaction operation.

[0040] According to several embodiments of the present invention, the gas inlet 11 of the chlorine buffer tank 1 is located at a height of 500-1000 mm above the bottom of the tank, and the gas outlet 14 of the chlorine buffer tank 1 is located at the top of the tank and is connected to the chlorine pipeline 3.

[0041] As a feasible embodiment, the core function of the chlorine buffer tank 1 is to purify and stabilize the circulating chlorine gas. Its gas inlet 11 is located at a certain height above the bottom of the tank, for example, 500mm, 800mm, or 1000mm from the bottom. This height setting is intended to provide accumulation space for dust that may settle, preventing it from clogging the inlet pipe. An ultrasonic agglomeration device 12 is integrated at the gas inlet 11. This device generates high-frequency mechanical vibrations, for example, at a frequency of 20-40kHz, acting on the flowing dust-laden gas, causing the suspended fine titanium dioxide particles in the gas to collide and agglomerate, forming larger, more easily settling agglomerates.

[0042] According to several embodiments of the present invention, the number of horizontal baffles 13 is 2-5 sets, and the horizontal baffles 13 are arranged obliquely downwards and form an angle of 1-5° with the horizontal plane. Preferably, the number of baffles is 2, 3, 4 or 5 sets. These baffles are fixed horizontally or nearly horizontally to the inner wall of the tank. More preferably, the horizontal baffles 13 can be arranged slightly obliquely downwards, that is, their plane forms a small angle of 1-5° with the horizontal plane. This tilt angle helps the agglomerated particles deposited on the baffles to slide down to the edge of the baffle under the action of gravity and eventually fall into the bottom of the tank, playing a guiding role and preventing dust from accumulating in the center of the baffle plane. When the airflow carrying agglomerated particles passes through these baffles, the flow cross section changes continuously, and the airflow direction and speed change frequently, causing the agglomerated particles to separate from the gas due to inertial collision and kinetic energy loss, and settle on the surface of the baffles and the bottom of the tank, thereby achieving deep purification of the gas. The purified gas is discharged from the gas outlet 14 located at the top of the buffer tank and enters the chlorination pipeline 3. This process also buffers gas pressure fluctuations from the preceding oxidation process.

[0043] According to several embodiments of the present invention, the angle between the tangential direction of the tangentially lower inlet 21 and the horizontal direction is 5-15°.

[0044] According to several embodiments of the present invention, the projection of the axis of the tangentially lower inlet 21 onto the horizontal plane has an angle of 20-40° with the circumferential tangent of the chlorination furnace body 2 at the tangentially lower inlet 21.

[0045] In one specific embodiment, the chlorination pipe 3 is connected to the side wall of the chlorination furnace body 2, and its end forms a tangentially downward inlet 21 within the furnace body. The spatial orientation of this inlet is defined by two key angles: first, the angle between the tangential direction and the horizontal direction, i.e., the acute angle between the central axis of the inlet pipe and the horizontal plane, which ranges from 5-22°, preferably from 5-15°, for example, 5°, 10°, or 15°. This angle determines the degree to which the gas flow slopes downwards when entering the molten pool. Second, the angle between the projection of the axis onto the horizontal plane and the tangent of the circumference of the chlorination furnace body 2 at the inlet, which ranges from 20-40°, for example, 25°, 35°, etc. This angle determines the degree to which the gas flow deviates from the purely tangential direction within the horizontal plane, affecting the vortex shape. The combination of these two angles ensures that the circulating chlorine gas enters below the molten salt surface in a spiraling, downward-moving vortex form that adheres closely to the furnace wall. This air intake method greatly reduces the direct impact on the molten pool surface, thus reducing energy loss. At the same time, the swirling motion significantly prolongs the residence path and time of bubbles in the molten pool, and promotes the breaking and uniform distribution of large bubbles, thereby enhancing the mass transfer and reaction efficiency between low-concentration chlorine gas and solid components such as titanium-containing materials and petroleum coke in the molten pool.

[0046] According to several embodiments of the present invention, the system further includes an online chlorine concentration detection device and a molten salt level control device. The online chlorine concentration detection device is installed on the chlorine pipeline 3 and is used to detect the chlorine concentration in the circulating chlorine in real time. The molten salt level control device is interlocked with the online chlorine concentration detection device and is used to dynamically adjust the molten salt level in the chlorination furnace body 2 according to the detected chlorine concentration.

[0047] Specifically, in some more sophisticated system embodiments, the system also integrates an automatic control unit. An online chlorine concentration detection device, such as an online analyzer using ultraviolet absorption or laser spectroscopy, is installed on the chlorine pipeline 3 to monitor the Cl2 volume concentration in the circulating chlorine gas in real time. This detection device is signal-interlocked with the molten salt level control device of the chlorination furnace body 2. The molten salt level control device typically includes level detection instruments, such as radar level gauges or differential pressure level gauges, and a salt discharge actuator, such as a salt discharge valve.

[0048] According to several embodiments of the present invention, when the online chlorine concentration detection device detects a 1 percentage point decrease in the volume concentration of circulating chlorine, the molten salt level control device is set to increase the molten salt level by 0.05-0.15 m. This interlocking control logic is configured such that when the online detection device detects a decrease in chlorine concentration, the control system issues a command to correspondingly increase the molten salt level in the chlorination furnace by slowing down or suspending salt discharge. As a precise control strategy, for example, the control system is set such that for every 1 percentage point decrease in chlorine volume concentration, the target value for the molten salt level is increased by 0.05 to 0.15 meters. By increasing the level, the travel distance of bubbles from the inlet to the escaping liquid surface is increased, thereby forcibly extending the residence time of chlorine in the reaction zone to compensate for the weakened driving force of the chemical reaction due to the decrease in concentration, ensuring that the chlorine utilization rate and reaction rate are maintained at an appropriate level.

[0049] According to several embodiments of the present invention, the chlorination furnace body 2 includes a waste salt discharge port 22 located on the side wall and a flue gas outlet 23 located at the top. The height of the waste salt discharge port 22 is 5-6.5m, and the height of the molten salt liquid level inside the chlorination furnace body 2 is 5-7.5m.

[0050] According to several embodiments of the present invention, the production capacity load of the chlorination furnace body 2 is in the range of 220-320 t / d.

[0051] As a more specific embodiment, the chlorination furnace body 2 has a waste salt discharge port 22 on its side wall for periodically discharging the waste salt produced in the reaction. The height of the discharge port, i.e., the distance from its lower edge to the furnace bottom, is designed to be 5 to 6.5 meters, for example, 5.2 meters, 6 meters, or 6.5 meters. Correspondingly, the operating height range of the molten salt level is typically controlled between 5 and 7.5 meters. This design provides sufficient operational flexibility for the system when a higher liquid level is required to cope with low concentrations of chlorine gas. With the support of this system and method, the chlorination furnace body 2 can stably operate within a high-load range (based on titanium tetrachloride production) of 220 to 320 tons per day (t / d).

[0052] This invention also provides a method for treating circulating chlorine gas in a molten salt chlorination furnace; please refer to [reference needed]. Figure 3 , Figure 3 A flowchart of a circulating chlorine gas treatment method for a molten salt chlorination furnace according to another embodiment of the present invention is shown, as follows: Figure 3 As shown, it includes:

[0053] Step a: Introduce circulating chlorine gas into the chlorine buffer tank through the gas inlet.

[0054] Step b: Turn on the ultrasonic agglomeration device to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas.

[0055] Step c: Pass the circulating chlorine gas carrying agglomerated particles through the horizontal baffle to promote the settling of the agglomerated particles;

[0056] Step d: The purified circulating chlorine gas is introduced into the main body of the chlorination furnace through a tangentially downward inlet in a swirling manner;

[0057] Step e: Control the residence time of the purified circulating chlorine gas in the main body of the chlorination furnace to be 5-20 seconds.

[0058] To further understand the circulating chlorine gas treatment system 100 and method for a molten salt chlorination furnace provided by the present invention, in Figure 1-2 Based on this, the following more specific embodiments will be described in further detail.

[0059] Example 1

[0060] The circulating chlorine gas has a Cl2 volume concentration of 75% and an O2 volume concentration of 5%, with a total chlorine mass flow rate of 14 t / h and a chlorination furnace main body 2 capacity load of 300 t / d. When the molten salt chlorination titanium dioxide oxidation unit is connected to the chlorination unit, the ultrasonic agglomeration device 12 is activated. After the circulating chlorine gas passes through the ultrasonic agglomeration device 12, the residual nano- to micron-sized titanium dioxide particles agglomerate and enter the chlorine buffer tank 1 with the gas flow. Three sets of horizontal baffles 13 are installed in the buffer tank from bottom to top, and these horizontal baffles 13 are arranged obliquely downwards at a 3° angle to the horizontal plane. The circulating chlorine gas mixed with agglomerated particles slows down and changes direction within the tank, and the particles gradually deposit at the bottom of the tank due to the decrease in momentum and velocity. The purified gas is distributed to five sets of chlorine pipes 3 and enters the chlorination furnace main body 2. The chlorination pipeline 3 has a tangentially lower inlet 21 on the side wall of the chlorination furnace body 2. The angle between the tangential direction and the horizontal direction is 22°, and the angle between the projection of the inlet axis on the horizontal plane and the circumferential tangent of the chlorination furnace body 2 at that location is 35°. The gas enters the chlorination furnace body 2 in this swirling manner, effectively agitating the molten pool and reacting with the solid materials therein. Under this condition, the waste salt discharge port 22 is 5.2 meters high, and the molten salt level is controlled between 5.5 meters and 6.2 meters; when the level exceeds 6.2 meters, a salt discharge operation is performed to lower the level back to 5.5 meters.

[0061] Example 2

[0062] In another specific embodiment, the Cl2 volume concentration in the circulating chlorine gas is reduced to 65%, the O2 volume concentration is 8%, the total chlorine mass flow rate is 15.5 t / h, and the capacity load of the chlorination furnace body 2 is maintained at 295 t / d. The system startup process is the same as in Example 1. The circulating chlorine gas is treated by the ultrasonic agglomeration device 12 and purified in the chlorine buffer tank 1 equipped with three sets of horizontal baffles 13 (slanted downwards at 3°). After purification, the gas enters the chlorination furnace body 2 through six sets of chlorine pipes 3. The pipe inlet angle configuration is the same as in Example 1 (horizontal included angle 22°, tangential angle 35°). The key difference from Example 1 is that, in order to cope with the reduction in chlorine concentration, the system increases the molten salt level to prolong the reaction residence time. Under this condition, the height of the waste salt discharge port 22 is still 5.2 meters, but the molten salt level is controlled in a higher range of 6.5 meters to 7.2 meters; when the level exceeds 7.2 meters, a salt discharge operation is performed to lower the level back to 6.5 meters. This operation embodies the core method of dynamically adjusting process parameters based on the concentration of chlorine gas entering the furnace to adapt to concentration fluctuations.

[0063] Example 3

[0064] In Example 3, the Cl2 volume concentration in the circulating chlorine gas is 60%. The capacity load of the chlorination furnace body 2 is set to 220 t / d. Under this low concentration condition, the ultrasonic agglomeration device 12 works in conjunction with the chlorine buffer tank 1 to purify the gas. The chlorine buffer tank 1 is equipped with only one set of horizontal baffles 13, which are arranged obliquely downwards at a 1° angle to the horizontal plane. The purified gas enters the chlorination furnace body 2 through the chlorination pipeline 3. The tangentially lower inlet 21 of the chlorination furnace body 2 adopts a gentler angle, with its tangential direction at a 5° angle to the horizontal direction, and its axis projection on the horizontal plane at a 20° angle to the circumferential tangent. Under this configuration, to compensate for the extremely low chlorine concentration, the molten salt level is raised and stabilized at a high level of 7.5 meters through an interlocking control system. The height of the waste salt discharge port 22 is correspondingly set to above 7.5 meters, such as 7.6 meters, to ensure safe operation at high liquid levels. The residence time of chlorine in the molten pool is controlled to approximately 20 seconds to ensure sufficient reaction.

[0065] Example 4

[0066] In Example 4, the Cl2 volume concentration in the circulating chlorine gas is 90%. The chlorination furnace body 2 operates under high load, with a capacity load of 320 t / d. During stable system operation, all five sets of horizontal baffles 13 in the chlorine buffer tank 1 are in use, with the horizontal baffles 13 angled downwards at 5° to efficiently capture and guide dust. The purified gas enters the chlorination furnace body 2 through the chlorine pipe 3, with the tangential direction of its tangentially lower inlet 21 forming an angle of 15° with the horizontal direction. Under this condition, due to the high chlorine concentration and strong reaction driving force, the molten salt level can be set at 5.0 meters through interlocking control to meet the reaction requirements, and the residence time of chlorine in the molten pool is approximately 5 seconds. The waste salt discharge port 22 is set at a height of 5.0 meters to match the low liquid level operation.

[0067] Example 5

[0068] In Example 5, the initial system state was: Cl2 volume concentration in the circulating chlorine gas was 70%, and the molten salt level was 6.0 meters. When the online chlorine concentration detection device detected a rapid drop in concentration to 68%, the molten salt level control device responded immediately. The system raised the target level control value by 0.10 meters, adjusting the molten salt level from 6.0 meters to 6.1 meters. This process was achieved by temporarily delaying salt discharge, demonstrating the system's adaptive control capability to adjust key operating parameters in real time and automatically based on the chlorine concentration entering the furnace to stabilize reaction efficiency.

[0069] As can be seen from Examples 1-5 above, the circulating chlorine treatment system for molten salt chlorination furnaces provided in this application effectively solves the technical problems of rutile TiO2 dust clogging pipes and low reaction efficiency of low-concentration chlorine gas through the process flow of ultrasonic agglomeration-buffer tank baffle settling-tangential vortex inflow into the furnace. Examples 1-5 demonstrate that the circulating chlorine treatment system for molten salt chlorination furnaces provided in this application successfully handles various operating conditions with circulating chlorine concentrations ranging from a lower limit of 60% to an upper limit of 90%, and the chlorination furnace body 2's production capacity ranging from a lower limit of 220t / d to an upper limit of 320t / d, as well as the effectiveness of single-group horizontal baffles 13 to five-group horizontal baffles 13 and different combinations of tangential inlet angles. Furthermore, the circulating chlorine treatment system for molten salt chlorination furnaces provided in this application can operate stably within a wide range of molten salt levels from 5.0 meters to 7.5 meters, achieving chlorine residence times from 5 seconds to 20 seconds.

[0070] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0071] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A circulating chlorine gas treatment system for a molten salt chlorination furnace, characterized in that, Includes a chlorine buffer tank, a chlorination furnace body, and chlorine pipelines connecting the two; The chlorine buffer tank is equipped with an ultrasonic agglomeration device at the gas inlet, which is used to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas introduced from the gas inlet. The chlorine buffer tank has at least one set of horizontal baffles inside the gas flow path, which are used to promote the settling of agglomerated particles. The chlorine pipeline is connected to a tangentially lower inlet on the side wall of the chlorination furnace body. The tangential direction of the tangentially lower inlet makes an angle of 5-22° with the horizontal direction, which is used to allow the circulating chlorine gas to enter the chlorination furnace body in a swirling manner.

2. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The gas inlet of the chlorine buffer tank is located at a height of 500-1000mm above the bottom of the tank, and the gas outlet of the chlorine buffer tank is located at the top of the tank and connected to the chlorine pipeline.

3. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The number of horizontal baffles is 2-5, and the horizontal baffles are set obliquely downward and form an angle of 1-5° with the horizontal plane.

4. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The angle between the tangential direction of the downward tangential inlet and the horizontal direction is 5-15°.

5. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The projection of the axis of the tangentially lower inlet onto the horizontal plane has an angle of 20-40° with the circumferential tangent of the chlorination furnace body at the tangentially lower inlet.

6. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The system also includes an online chlorine concentration detection device and a molten salt level control device. The online chlorine concentration detection device is installed on the chlorine pipeline and is used to detect the chlorine concentration in the circulating chlorine in real time. The molten salt level control device is interlocked with the online chlorine concentration detection device and is used to dynamically adjust the molten salt level in the chlorination furnace body according to the detected chlorine concentration.

7. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 6, characterized in that, When the online chlorine concentration detection device detects a 1 percentage point decrease in the volume concentration of the circulating chlorine, the molten salt level control device is set to increase the molten salt level by 0.05-0.15m.

8. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The main body of the chlorination furnace includes a waste salt discharge port on the side wall and a flue gas outlet at the top. The height of the waste salt discharge port is 5-6.5m, and the height of the molten salt liquid level inside the main body of the chlorination furnace is 5-7.5m.

9. The circulating chlorine gas treatment system for a molten salt chlorination furnace according to claim 1, characterized in that, The main body of the chlorination furnace has a production capacity load in the range of 220-320t / d.

10. A method for treating circulating chlorine gas using the system according to any one of claims 1-9, characterized in that, include: Step a: Introduce circulating chlorine gas into the chlorine buffer tank through the gas inlet; Step b: Turn on the ultrasonic agglomeration device to agglomerate the titanium dioxide particles entrained in the circulating chlorine gas. Step c: Pass the circulating chlorine gas carrying agglomerated particles through the horizontal baffle to promote the settling of the agglomerated particles; Step d: The purified circulating chlorine gas is introduced into the main body of the chlorination furnace through the tangentially downward inlet in a swirling manner; Step e: Control the residence time of the purified circulating chlorine gas in the main body of the chlorination furnace to be 5-20 seconds.

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