Fluidized drying method for vanadium slurry in crude titanium tetrachloride

Abstract

The invention provides a fluidized drying method for vanadium slurry in crude titanium tetrachloride, and relates to the technical field of titanium tetrachloride refining. The method comprises the following steps: filling a fluidized bed medium; purging the fluidized bed and the pipeline to preset conditions; preheating the fluidized bed to a preset temperature; evaluating the influence of the reaction temperature on the evaporation efficiency and the outlet temperature to obtain an optimal parameter combination; dynamically adjusting the nitrogen pressure to maintain the fluidization stability; according to the optimal parameter combination, the flow of the liquefied petroleum gas is dynamically adjusted through a PID algorithm, and the reaction temperature is maintained; a metal filter bag is used for intercepting solid residues, and a negative pressure connector is used for collecting tail gas. Through multi-dimensional technical innovation and process optimization, high efficiency, safety and environmental protection of the fluidized drying process of the crude titanium tetrachloride vanadium slurry are realized. Through dynamic pressure regulation, the energy utilization efficiency is optimized, the operation cost is reduced, meanwhile, the equipment maintenance frequency is reduced, the service life of core components is prolonged, and the production continuity and the resource utilization rate are comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium tetrachloride refining, and particularly to a fluidized drying method for vanadium mud in crude titanium tetrachloride. Background Art

[0002] In the process of titanium tetrachloride refining, vanadium-containing mud is one of the core by-products in titanium dioxide production. It is generated from the solid-liquid separation link after the inactivation of vanadium catalyst in the chlorination process. The mass fraction of titanium tetrachloride in the mud is usually as high as 30% - 50%, and it also contains vanadium oxides, aluminum oxides and a small amount of residual chlorine. Due to the strong corrosiveness and volatility of titanium tetrachloride, directly spraying it into the chlorination process will cause catalyst poisoning, equipment corrosion and chlorine leakage risks, so harmless treatment is required. Currently, the mainstream treatment technologies are divided into dry method and wet method: the wet process converts vanadium into soluble salts through acid leaching or alkali dissolution, but it will produce a large amount of chlorine-containing wastewater and acidic waste gas. When producing on a large scale, the environmental protection treatment cost accounts for more than 40% of the operating cost, and it is difficult to meet the "Discharge Standard of Titanium Dioxide Industry Wastewater"; the dry process takes slurry evaporation as the core, vaporizes and recovers titanium tetrachloride at high temperature (450 - 600 °C), and the vanadium slag is landfilled after rapid cooling and solidification.

[0003] Due to the high content of titanium tetrachloride in the mud, due to environmental protection requirements, the wet process is not suitable for large-scale production. Currently, batch evaporation treatment is mostly carried out using a slurry evaporation furnace. With the increase in production scale, the investment in intermittent evaporation of the mud is high and the efficiency is low. Especially after adopting the vanadium removal process with mineral oil, the dried tail slag generated by electric heating kettle evaporation is prone to spontaneous combustion during the discharging process, posing certain safety hazards, and new processes suitable for this are needed to be developed. Summary of the Invention

[0004] The present invention provides a fluidized drying method for vanadium mud in crude titanium tetrachloride to solve the defects existing in the prior art.

[0005] The present invention provides a fluidized drying method for vanadium mud in crude titanium tetrachloride, including: Testing the escape rate of quartz sand, screening the particle size of quartz sand, and completing the filling of the fluidized bed medium.

[0006] Opening the nitrogen storage tank to purge the fluidized bed and pipelines to the preset conditions and then closing the nitrogen.

[0007] Starting the liquefied petroleum gas burner to preheat the fluidized bed to the preset temperature.

[0008] Evaluating the influence of the reaction temperature on the evaporation efficiency and the outlet temperature to obtain the best parameter combination.

[0009] Starting the nitrogen pressurization system to transport the materials in the crude titanium tetrachloride storage tank, and dynamically adjusting the nitrogen pressure according to the best parameter combination to maintain the fluidization stability.

[0010] According to the optimal parameter combination, the flow rate of liquefied petroleum gas is dynamically adjusted by the PID algorithm to maintain the reaction temperature.

[0011] Use a metal filter bag to intercept solid slag and use a negative pressure interface to collect tail gas.

[0012] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the process of screening the particle size of quartz sand includes: Collect quartz sand samples with different weights and particle sizes.

[0013] Perform screening and vibration tests under the preset temperature of 250 °C and the gas flow rate of 0.5 m / s.

[0014] Calculate the target particles when the escape rate ≤ 5%, and measure the physical parameters of the target particles. The physical parameters include weight and particle size.

[0015] Screen the particle size of quartz sand according to the physical parameters.

[0016] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the air pressure for purging the fluidized bed and pipelines is ≥ 0.3 MPa. The preset condition is that the oxygen content in the fluidized bed and pipelines ≤ 0.5%.

[0017] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the process of preheating the fluidized bed includes: Start the liquefied petroleum gas burner, and mix and burn the liquefied petroleum gas with compressed air in the hot blast stove to generate hot gas.

[0018] The hot gas is transported to the distributor through pipelines, and the distributor is used to evenly distribute the hot gas.

[0019] Use the evenly distributed hot gas to preheat the fluidized bed.

[0020] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the preset temperature is 500 °C.

[0021] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the process of evaluating the influence of the reaction temperature on the evaporation efficiency and the outlet temperature and obtaining the optimal parameter combination includes: Adopt the Taguchi orthogonal experiment method to screen the key parameters. The key parameters include the total feed mass, the feed moisture content, the total discharge mass, and the discharge moisture content.

[0022] Compare the difference in moisture content between the feed and the discharge, and quantify the dehydration efficiency of the drying process. The formula is expressed as:

[0023] In the formula, represents the dehydration efficiency, represents the total mass of the feed, represents the moisture content of the feed, represents the total mass of the discharge, represents the moisture content of the discharge.

[0024] Based on the statistical variance, the stability of the outlet temperature is calculated, and the formula is expressed as:

[0025] In the formula, represents the outlet temperature fluctuation, represents the th sampled outlet temperature, represents the average outlet temperature, and s represents the number of samplings.

[0026] Collect data with a dehydration efficiency ≥ 95% and an outlet temperature fluctuation ≤ ±5°C, establish a response surface model to optimize the parameters. Through second-order polynomial fitting of the non-linear relationship between the reaction temperature, feed rate, and nitrogen pressure, optimize multiple objectives to obtain the optimal parameter combination, and the optimal parameter combination includes nitrogen pressure and reaction temperature.

[0027] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the process of dynamically adjusting the nitrogen pressure to maintain fluidization stability includes: Establish a linear relationship model between the nitrogen pressure and the feed rate, and the formula is expressed as:

[0028] In the formula, represents the feed rate of crude titanium tetrachloride, represents the nitrogen pressure, represents the pressure flow coefficient, represents the basic leakage.

[0029] The pressure drop of the fluidized bed is monitored in real time through a differential pressure sensor, and a fluidized bed pressure drop threshold is set. When the fluidized bed pressure drop reaches the fluidized bed pressure drop threshold, a nitrogen pressure compensation mechanism is triggered, and the formula of the nitrogen pressure compensation mechanism is expressed as:

[0030] In the formula, represents the compensated nitrogen pressure, represents the original nitrogen pressure, represents the pressure compensation coefficient, represents the fluidized bed pressure drop, represents the target pressure drop.

[0031] A fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention. The process of real-time monitoring of the fluidized bed pressure drop by a differential pressure sensor includes: A laser particle size analyzer emits a laser beam, and the particle size distribution of suspended particles is calculated through a scattering model. The formula is expressed as:

[0032] In the formula, represents the light intensity received by the detector at the scattering angle , represents the particle scattering function, represents the phase difference of the i-th particle, represents the original light intensity of the incident laser, r represents the distance from the laser beam to the detector, and n represents the total number of suspended particles.

[0033] Based on the Ergun equation, the fluidized bed pressure drop is correlated with the fluidized bed parameters. The formula is expressed as:

[0034] In the formula, represents the fluidized bed pressure drop, represents the gas viscosity, represents the bed porosity, represents the superficial gas velocity, represents the average particle size of the suspended particles, represents the distributor aperture, represents the mass volume density of the gas in the fluidized bed.

[0035] A fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention. The process of dynamically adjusting the flow rate of liquefied petroleum gas through the PID algorithm according to the optimal parameter combination includes: Initialize the PID controller parameters. The controller parameters include the proportional coefficient, integral coefficient, and differential coefficient.

[0036] Use a temperature sensor to sample the reaction temperature in the fluidized bed at a preset period and compare it with the preset temperature set in advance to calculate the temperature deviation at the current moment.

[0037] Calculate the control output according to the temperature deviation at the current moment, the temperature deviation at the previous moment, and the deviation integral. The formula is expressed as:

[0038] In the formula, represents the control output, represents the proportional coefficient, represents the integral coefficient, represents the differential coefficient, represents the temperature deviation at the current moment, represents the temperature deviation at the previous moment, represents the time interval, represents the integral of deviation.

[0039] Convert the control output into the opening control signal of the liquefied petroleum gas flow regulating valve to adjust the valve opening.

[0040] According to a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention, the solid slag includes a mixture of TiO2, V2O5 and Al2O3. The tail gas includes HCl, TiOCl2 and unreacted TiCl4.

[0041] A fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the present invention realizes the high efficiency, safety and environmental protection of the fluidized drying process of vanadium mud in crude titanium tetrachloride through multi-dimensional technological innovation and process optimization. Through the collaborative application of the Taguchi orthogonal experiment method and the response surface method, a multi-parameter collaborative optimization model of temperature, feeding rate and nitrogen flow rate is constructed, breaking through the limitations of traditional single-parameter control, significantly improving the stability and efficiency of the drying process, and reducing energy consumption and material loss at the same time. By introducing a dynamic pressure compensation mechanism and real-time feedback regulation of fluidized bed parameters, the uniform fluidization state of the bed layer is effectively maintained, abnormal phenomena such as channeling and slugging are suppressed, equipment wear and shutdown risks are reduced, and the service life of the device is extended. The whole process is protected by nitrogen and a hierarchical interlock control strategy is adopted, combined with an intelligent PID algorithm to accurately control the reaction temperature, eliminate potential fire and explosion hazards, avoid coking problems caused by local overheating, and greatly improve operation safety and equipment reliability. Through a multi-stage tail gas purification system, deep removal of harmful substances is realized, pollutant emissions are reduced, meeting the requirements of green manufacturing and circular economy. Through dynamic pressure regulation, the energy utilization efficiency is optimized, the operation cost is reduced, the equipment maintenance frequency is reduced at the same time, the service life of the core components is extended, and the production continuity and resource utilization rate are comprehensively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0043] Figure 1 is a schematic flow chart of a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by an embodiment of the present invention; Figure 2 is a framework diagram of a fluidized drying system for vanadium mud in crude titanium tetrachloride provided by this embodiment; Figure 3It is a schematic diagram of the results of material balance and heat balance provided by the embodiments of the present invention. Detailed implementation manners

[0044] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0045] The following Figures 1 - 3 describes a fluidized drying method for vanadium mud in crude titanium tetrachloride of the present invention.

[0046] Figure 1 It is a schematic flow diagram of a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the embodiments of the present invention.

[0047] As Figure 1 shown, a fluidized drying method for vanadium mud in crude titanium tetrachloride provided by the embodiments of the present invention includes: Testing the escape rate of quartz sand, screening the particle size of quartz sand, and completing the filling of the fluidized bed medium.

[0048] The process of screening the particle size of quartz sand includes: Using the stratified random sampling method, different points are selected from the raw quartz sand pile, samples are taken from each point, and after being combined, quartz sand samples with different weights and particle sizes are formed. The samples are placed in an oven at 105°C for 4 hours to remove adsorbed moisture, and particles larger than 400μm and smaller than 200μm are removed using a standard sieve (sieve mesh accuracy ±50μm), and the samples in the intermediate particle size range are retained.

[0049] Carrying out screening and vibration tests under the conditions of a preset temperature of 250°C and a gas flow rate of 0.5m / s.

[0050] Calculating to screen out target particles when the escape rate ≤ 5%, and measuring the physical parameters of the target particles. The physical parameters include weight and particle size.

[0051] Screening the particle size of quartz sand according to the physical parameters and carrying out the filling of the fluidized bed medium. Using the stratified vibration filling method, it is filled in 3 layers (each layer is 500mm high), and after each layer is filled, a pneumatic vibrator (frequency 20Hz, amplitude 1mm) is used to compact it to eliminate voids. During the filling process, a stainless steel diversion plate (opening rate 30%) is inserted to guide the uniform distribution of quartz sand and avoid local accumulation.

[0052] Verify the bed layer uniformity after loading, and the pressure drop fluctuation range ≤ 10%. Install a differential pressure sensor (range 0 - 10 kPa, accuracy ±0.5% FS) at the bottom and top of the fluidized bed. Introduce nitrogen (flow rate 0.5 m / s), record the bed layer pressure drop for 30 minutes, and calculate the volatility. The required volatility ≤ 10%, otherwise adjust the loading density or replace the distributor.

[0053] Open the nitrogen storage tank to purge the fluidized bed and pipelines until the preset conditions are reached, then close the nitrogen.

[0054] The air pressure for purging the fluidized bed and pipelines is ≥ 0.3 MPa. The preset conditions are that the oxygen content in the fluidized bed and pipelines ≤ 0.5%. The purge gas flow rate is 20 Nm³ / h, corresponding to a linear velocity of 1.2 m / s, ensuring that the replacement efficiency can be achieved. The purge is carried out in three stages, including: the first stage, purge with 0.3 MPa nitrogen for 30 minutes to make the oxygen content ≤ 5%; the second stage, purge with 0.4 MPa nitrogen for 15 minutes to make the oxygen content ≤ 1%; the third stage, maintain the pressure with 0.5 MPa nitrogen for 10 minutes, and the oxygen content ≤ 0.5%.

[0055] The oxygen content monitoring points are located at the top, middle of the fluidized bed and the outlet pipeline. Stop purging when the detected oxygen content ≤ 0.5%.

[0056] Start the liquefied petroleum gas burner to preheat the fluidized bed to the preset temperature. The preset temperature is 500 °C.

[0057] The process of preheating the fluidized bed includes: Start the liquefied petroleum gas burner to mix and burn liquefied petroleum gas with compressed air in the hot blast stove to generate hot gas. The liquefied petroleum gas and compressed air are mixed and burned at a volume ratio of 5:1, and the hot gas temperature ≤ 400 °C.

[0058] The hot gas is transported through the pipeline to the distributor, and the distributor is used to evenly distribute the hot gas. The hot gas enters the fluidized bed evenly through the porous distributor. The porosity of the distributor is 30% - 50%, the average pore diameter is 3 mm, it is made of Hastelloy C - 276, with a honeycomb - like porous structure and a thickness ≥ 5 mm, ensuring uniform diffusion of the hot gas while preventing thermal deformation.

[0059] Use the uniformly distributed hot gas to preheat the fluidized bed. Preheat to the preset temperature at a heating rate of 10 °C / min and keep it warm for 1 hour.

[0060] In this embodiment, an over - temperature protection mechanism is also set. When the bed layer temperature > 510 °C, an emergency shutdown is automatically triggered. At the same time, the gas valve is closed, nitrogen purging is started, and the flow rate is increased to 500 Nm³ / h. And a zirconia sensor is arranged at the outlet of the distributor, with an accuracy of ±0.5% O2. When the oxygen concentration > 5%, an alarm is given and the fuel supply is cut off.

[0061] Evaluate the influence of reaction temperature on evaporation efficiency and outlet temperature to obtain the optimal parameter combination. The process includes: Adopt the Taguchi orthogonal experiment method to screen key parameters, which include the total feed mass, feed moisture content, total discharge mass, and discharge moisture content. For the orthogonal experiment design, the variables are temperature (450 - 550 °C) and feed rate (30 - 70 kg / h).

[0062] Compare the difference in moisture content between the feed and the discharge, and quantify the dehydration efficiency during the drying process. The formula is expressed as:

[0063] In the formula, represents the dehydration efficiency, represents the total feed mass, represents the feed moisture content, represents the total discharge mass, represents the discharge moisture content.

[0064] Calculate the stability of the outlet temperature based on statistical variance. The formula is expressed as:

[0065] In the formula, represents the outlet temperature fluctuation, represents the th sampled outlet temperature, represents the average outlet temperature, and s represents the number of samplings.

[0066] Collect data with a dehydration efficiency ≥ 95% and an outlet temperature fluctuation ≤ ±5 °C, and establish a response surface model to optimize the parameters. Fit the non - linear relationship among reaction temperature, feed rate, and nitrogen pressure through a second - order polynomial, optimize multiple objectives, and obtain the optimal parameter combination, which includes nitrogen pressure and reaction temperature.

[0067] The process of establishing a response surface model to optimize the parameters includes: Establish a quadratic regression equation for dehydration efficiency with respect to reaction temperature and feed rate. The formula is expressed as:

[0068] In the formula, represents the dehydration efficiency, represents the model constant term, represents the linear coefficient of reaction temperature, represents the linear coefficient of feed rate, represents the linear coefficient of nitrogen pressure, A represents the reaction temperature, B represents the feed rate, C represents the nitrogen pressure, represents the quadratic term coefficient of reaction temperature, represents the quadratic coefficient of the feed rate, represents the interaction coefficient between the reaction temperature and the feed rate, represents the model error.

[0069] The linear coefficients are solved using the least squares method, and the multi-objective optimization problem is solved through the genetic algorithm to obtain the optimal parameter combination.

[0070] Start the nitrogen pressurization system to transport the materials in the crude titanium tetrachloride storage tank, and the nitrogen pressure is set in the range of 0.4 - 0.8 MPa. And dynamically adjust the nitrogen pressure according to the optimal parameter combination to maintain the fluidization stability.

[0071] The process of dynamically adjusting the nitrogen pressure to maintain the fluidization stability includes: Establish a linear relationship model between the nitrogen pressure and the feed rate, which is expressed by the formula:

[0072] In the formula, represents the feed rate of the crude titanium tetrachloride, represents the nitrogen pressure, represents the pressure-flow coefficient, represents the basic leakage.

[0073] The pressure drop of the fluidized bed is monitored in real time through a differential pressure sensor, and a fluidized bed pressure drop threshold is set. When the fluidized bed pressure drop reaches the fluidized bed pressure drop threshold, the nitrogen pressure compensation mechanism is triggered. The formula of the nitrogen pressure compensation mechanism is expressed as:

[0074] In the formula, represents the compensated nitrogen pressure, represents the original nitrogen pressure, represents the pressure compensation coefficient, represents the fluidized bed pressure drop, represents the target pressure drop.

[0075] The process of monitoring the fluidized bed pressure drop in real time through a differential pressure sensor includes: A laser particle size analyzer is used to emit a laser beam, and the particle size distribution of the suspended particles is calculated through a scattering model, which is expressed by the formula:

[0076] In the formula, represents the light intensity received by the detector at the scattering angle , represents the particle scattering function, represents the phase difference of the i-th particle, represents the original light intensity of the incident laser, r represents the distance from the laser beam to the detector, and n represents the total number of suspended particles.

[0077] Based on the Ergun equation, the pressure drop of the fluidized bed is correlated with the fluidized bed parameters, which include gas viscosity, bed porosity, superficial gas velocity, average particle size of the suspended particles, distributor aperture, and mass-volume density of the gas in the fluidized bed. The correlation formula is expressed as:

[0078] In the formula, represents the pressure drop of the fluidized bed, represents the gas viscosity, represents the bed porosity, represents the superficial gas velocity, represents the average particle size of the suspended particles, represents the distributor aperture, represents the mass-volume density of the gas in the fluidized bed.

[0079] According to the optimal parameter combination, the flow rate of liquefied petroleum gas is dynamically adjusted through the PID algorithm to maintain the reaction temperature. The process includes: Initialize the parameters of the PID controller, and the controller parameters include proportional coefficient, integral coefficient, and differential coefficient.

[0080] Use the temperature sensor to sample the reaction temperature in the fluidized bed at a preset period, and compare it with the preset temperature, and calculate the temperature deviation at the current moment.

[0081] Calculate the control output according to the temperature deviation at the current moment, the temperature deviation at the previous moment, and the deviation integral. The formula is expressed as:

[0082] In the formula, represents the control output, represents the proportional coefficient, represents the integral coefficient, represents the differential coefficient, represents the temperature deviation at the current moment, represents the temperature deviation at the previous moment, represents the time interval, represents the deviation integral.

[0083] Convert the control output into an opening control signal for the liquefied petroleum gas flow regulating valve to adjust the valve opening.

[0084] Use a metal filter bag to intercept solid slag and use a negative pressure interface to collect the tail gas.

[0085] The solid slag includes a mixture of TiO2, V2O5 and Al2O3 with a particle size D90 ≤ 10 μm. The tail gas includes HCl, TiOCl2 and unreacted TiCl4.

[0086] In this embodiment, the vanadium-containing slurry generated during the purification of titanium tetrachloride has the following composition: Table 1: Composition of the refined vanadium-removing slurry: Combined with the characteristics of the vanadium-containing slurry, a new process of fluidized drying of the vanadium-containing slurry is proposed. Based on the material balance and heat balance calculations, a verification device with a scale of 50 kg / h is designed.

[0087] Figure 2 It is a framework diagram of a fluidized drying system for vanadium slurry in crude titanium tetrachloride provided in this embodiment.

[0088] As Figure 2 shown, the refined slurry fluidized drying device is arranged between the refining system and the rinsing system. The main equipment consists of a fluidized bed dryer (including a preheating device), a titanium tetrachloride storage tank and a filtering device. The required public auxiliary supporting conditions are process compressed air and nitrogen. The generated titanium tetrachloride-containing gas is returned to the main furnace secondary rinsing tower (or tail gas treatment system).

[0089] First, nitrogen is turned on to purge the system, and then the liquefied petroleum gas burner is turned on to preheat the system. When the system temperature reaches about 500 °C, titanium tetrachloride ore slurry is added dropwise to the fluidized bed. Since the ore slurry contains semicoke, the coke powder in the ore slurry reacts with the oxygen in the compressed air.

[0090] If the temperature of the fluidized bed is too high, the input of liquefied gas needs to be gradually reduced until it is closed. At the same time, volatile substances such as titanium tetrachloride in the slurry change from the liquid phase to the gas phase under the action of temperature, so as to achieve separation from other solids, becoming gas and dry particles. At the same time, easily oxidizable substances such as vanadium oxychloride in the vanadium-containing slurry react with the excess oxygen in the flue gas to form stable oxide particles.

[0091] The mixed gas composed of the flue gas, gaseous titanium tetrachloride and particulate matter after the reaction enters the filter equipped with a metal filter. Gaseous substances such as titanium tetrachloride and tail gas enter the recovery and purification device for further recovery and purification treatment. The particulate matter is regularly discharged from the lower part of the filter, so as to achieve the separation of solids and titanium tetrachloride in the refined slurry. The composition of the tail slag is as follows: Table 2: Composition of the refined tail slag: Figure 3 It is a schematic diagram of the results of material balance and heat balance provided in the embodiment of the present invention.

[0092] As Figure 3 shown, according to the ability to evaporate 50 kg / h of titanium tetrachloride, the material balance and heat balance of the system were calculated using ASPEN software. Through calculation, it is known that when the reaction rate of carbon powder in the slurry is 50% without considering heat loss, it is sufficient to maintain the temperatures of the gas phase and solid phase above 250°C after fluidized bed drying, and effective separation of titanium tetrachloride and solids can be achieved.

[0093] In summary, this embodiment provides a fluidized drying method for vanadium slurry in crude titanium tetrachloride. Through multi-dimensional technological innovation and process optimization, the efficiency, safety, and environmental friendliness of the fluidized drying process of crude titanium tetrachloride vanadium slurry are realized. Through the collaborative application of the Taguchi orthogonal experiment method and the response surface method, a multi-parameter collaborative optimization model of temperature, feed rate, and nitrogen gas flow rate is constructed, breaking through the limitations of traditional single-parameter control, significantly improving the stability and efficiency of the drying process, while reducing energy consumption and material loss. By introducing a dynamic pressure compensation mechanism and real-time feedback regulation of fluidized bed parameters, the uniform fluidization state of the bed layer is effectively maintained, abnormal phenomena such as channeling and slugging are suppressed, equipment wear and shutdown risks are reduced, and the service life of the device is extended. The whole process is protected by nitrogen and a hierarchical interlock control strategy is adopted, combined with an intelligent PID algorithm to accurately control the reaction temperature, eliminating potential explosion hazards and avoiding coking problems caused by local overheating, greatly improving operation safety and equipment reliability. Through a multi-stage tail gas purification system, deep removal of harmful substances is achieved, reducing pollutant emissions, meeting the requirements of green manufacturing and circular economy. Through dynamic pressure regulation, the energy utilization efficiency is optimized, the operating cost is reduced, the equipment maintenance frequency is reduced, the life of the core components is extended, and the production continuity and resource utilization rate are comprehensively improved.

[0094] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A fluidized drying method for vanadium mud in crude titanium tetrachloride, characterized in that, Including: Testing the escape rate of quartz sand, screening the particle size of quartz sand, and completing the filling of the fluidized bed medium; Opening the nitrogen storage tank to purge the fluidized bed and pipelines until reaching the preset conditions, and then closing the nitrogen; Starting the liquefied petroleum gas burner to preheat the fluidized bed to the preset temperature; Evaluating the influence of reaction temperature on evaporation efficiency and outlet temperature to obtain the optimal parameter combination; Starting the nitrogen pressurization system to transport the materials in the crude titanium tetrachloride storage tank, and dynamically adjusting the nitrogen pressure according to the optimal parameter combination to maintain the fluidization stability; Dynamically adjusting the liquefied petroleum gas flow rate through the PID algorithm according to the optimal parameter combination to maintain the reaction temperature; Using a metal filter bag to intercept solid slag and using a negative pressure interface to collect the tail gas.

2. The fluidized drying method of vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The process of screening the particle size of quartz sand includes: Collecting quartz sand samples with different weights and particle sizes; Carrying out screening and vibration tests under the conditions of a preset temperature of 250 °C and a gas flow rate of 0.5 m / s; Calculating to screen out the target particles when the escape rate ≤ 5%, and measuring the physical parameters of the target particles, where the physical parameters include weight and particle size; Screening the particle size of quartz sand according to the physical parameters.

3. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The air pressure for purging the fluidized bed and pipelines is ≥ 0.3 MPa; the preset conditions are that the oxygen content in the fluidized bed and pipelines ≤ 0.5%.

4. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The process of preheating the fluidized bed includes: Starting the liquefied petroleum gas burner to mix and burn liquefied petroleum gas with compressed air in the hot blast stove to generate hot gas; The hot gas is transported to the distributor through the pipeline, and the distributor is used to evenly distribute the hot gas; Using the evenly distributed hot gas to preheat the fluidized bed.

5. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The preset temperature is 500 °C.

6. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The process of evaluating the influence of reaction temperature on evaporation efficiency and outlet temperature to obtain the optimal parameter combination includes: Adopting the Taguchi orthogonal experiment method to screen the key parameters, where the key parameters include the total feed mass, feed moisture content, total discharge mass, and discharge moisture content; Comparing the difference in moisture content between the feed and the discharge, and quantifying the dehydration efficiency of the drying process, which is expressed by the formula: ； In the formula, represents the dehydration efficiency, represents the total mass of the feed, represents the moisture content of the feed, represents the total mass of the discharge, represents the moisture content of the discharge; Calculating the stability of the outlet temperature based on statistical variance, which is expressed by the formula: ； In the formula, represents the outlet temperature fluctuation, represents the outlet temperature at the th sampling, and s represents the number of samplings; Collecting data with a dehydration efficiency ≥ 95% and an outlet temperature fluctuation ≤ ±5 °C, establishing a response surface model to optimize the parameters, fitting the non-linear relationship between reaction temperature, feed rate, and nitrogen pressure through a second-order polynomial, optimizing multiple objectives, and obtaining the optimal parameter combination, where the optimal parameter combination includes nitrogen pressure and reaction temperature.

7. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The process of dynamically adjusting the nitrogen pressure to maintain the fluidization stability includes: Establishing a linear relationship model between nitrogen pressure and feed rate, which is expressed by the formula: ； In the formula, represents the feed rate of crude titanium tetrachloride, represents the nitrogen pressure, represents the pressure flow coefficient, represents the base leakage rate; Real-time monitoring the pressure drop of the fluidized bed through a differential pressure sensor, and setting a pressure drop threshold for the fluidized bed. When the pressure drop of the fluidized bed reaches the pressure drop threshold of the fluidized bed, triggering a nitrogen pressure compensation mechanism, and the formula of the nitrogen pressure compensation mechanism is expressed as: ； In the formula, represents the compensated nitrogen pressure, represents the original nitrogen pressure, represents the pressure compensation coefficient, represents the pressure drop of the fluidized bed, represents the target pressure drop.

8. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 6, characterized in that, The process of real-time monitoring the pressure drop of the fluidized bed through a differential pressure sensor includes: Using a laser particle size analyzer to emit a laser beam and calculating the particle size distribution of suspended particles through a scattering model, which is expressed by the formula: ； Wherein, represents the light intensity received by the detector at the scattering angle , represents the particle scattering function, represents the phase difference of the i-th particle, represents the original light intensity of the incident laser, r represents the distance from the laser beam to the detector, and n represents the total number of suspended particles; Relating the pressure drop of the fluidized bed to the fluidized bed parameters based on the Ergun equation, which is expressed by the formula: ； In the formula, represents the pressure drop of the fluidized bed, represents the gas viscosity, represents the bed porosity, represents the superficial gas velocity, represents the average particle size of the suspended particles, represents the distributor aperture, represents the mass volume density of the gas in the fluidized bed.

9. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that The process of dynamically adjusting the liquefied petroleum gas flow rate through the PID algorithm according to the optimal parameter combination includes: Initialize the PID controller parameters, where the controller parameters include the proportional coefficient, integral coefficient, and differential coefficient; Use a temperature sensor to sample the reaction temperature in the fluidized bed at a preset period, compare it with the preset temperature, and calculate the temperature deviation at the current moment; Calculate the control output based on the temperature deviation at the current moment, the temperature deviation at the previous moment, and the deviation integral. The formula is expressed as: ； Wherein, represents the control output, represents the proportional coefficient, represents the integral coefficient, represents the differential coefficient, represents the temperature deviation at the current moment, represents the temperature deviation at the previous moment, represents the time interval, represents the integral of the deviation; Convert the control output into an opening control signal for the liquefied petroleum gas flow regulating valve to adjust the valve opening.

10. A fluidized drying method for vanadium mud in crude titanium tetrachloride according to claim 1, characterized in that, The solid slag includes a mixture of TiO2, V2O5, and Al2O3; the tail gas includes HCl, TiOCl2, and unreacted TiCl4.

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