阅读说明：本技术 一种氧化反应器的防疤和除疤系统及其方法 (Scar preventing and removing system and method for oxidation reactor ) 是由 冯祥义 侯宝瑞 王景顺 乔仲春 高宏志 王安举 于 2019-10-29 设计创作，主要内容包括：一种氧化反应器的防疤和除疤系统,包括氧化反应器和防疤除疤装置,氧化反应器上设置有防疤除疤装置,防疤除疤装置包括第一冷却段气膜、第二冷却段气膜、第一打疤料入口、第二打疤料入口、第一甲苯枪冷却水管道、第二甲苯枪冷却水管道、炉中冷却水管道、炉尾冷却水管道、进料环、氮气吹扫管10、进料以及打疤管道、热氧气进口管、氯化钾进口管、四氯化钛预热器、氧气预热器、三氯化铝发生器、氯化钾溶液储罐、打疤料储罐、冷却导管、袋滤器、打浆罐、氯气管道、甲苯枪、四氯化钛进口管道阀门。(The utility model provides an oxidation reactor prevent scar and remove scar system, including oxidation reactor and prevent the scar and remove the scar device, be provided with on the oxidation reactor and prevent the scar and remove the scar device, prevent the scar and remove the scar device and include first cooling segment air film, second cooling segment air film, first scar material entry, second scar material entry, first toluene rifle water pipe, second xylene rifle cooling water pipe, stove tail cooling water pipe, the feeding ring, nitrogen gas sweeps pipe 10, feeding and pipeline, hot oxygen gas import pipe, potassium chloride import pipe, titanium tetrachloride preheater, oxygen gas, aluminium trichloride generator, potassium chloride solution storage tank, scar material storage tank, cooling conduit, bag filter, beating jar, chlorine pipeline, toluene rifle, titanium tetrachloride import pipeline valve.)

1. A scar preventing and removing system of an oxidation reactor comprises the oxidation reactor and a scar preventing and removing device, wherein the oxidation reactor is provided with the scar preventing and removing device, and the scar preventing and removing device comprises a first cooling section air film, a second cooling section air film, a first scar material inlet, a second scar material inlet, a first toluene gun water pipeline, a second xylene gun cooling water pipeline, a furnace tail cooling water pipeline, a feeding ring, a nitrogen purging pipe 10, a feeding and scarring pipeline, a hot oxygen inlet pipe, a potassium chloride inlet pipe, a titanium tetrachloride preheater, an oxygen preheater, an aluminum trichloride generator, a potassium chloride solution storage tank, a scar material storage tank, a cooling conduit, a bag filter, a pulping tank, a chlorine pipeline, a toluene gun and a titanium tetrachloride inlet pipeline valve;

the oxidation reactor is divided into a combustion section, a reaction section and a cooling section, a toluene gun is communicated with a hot oxygen inlet pipe at the combustion section, toluene and oxygen are mixed and combusted, oxygen at the hot oxygen inlet pipe is preheated by an oxygen preheater, potassium chloride in a potassium chloride solution storage tank enters the reaction section of the oxidation reactor through the potassium chloride inlet pipe to form a nucleating agent, a temperature measuring port is arranged on the reaction section of the oxidation reactor to monitor the reaction temperature, a feeding ring is arranged at the tail section of the reaction section, titanium tetrachloride passing through a titanium tetrachloride inlet pipeline valve is preheated in the titanium tetrachloride preheater, chlorine in a chlorine pipeline reacts with aluminum powder or aluminum particle aluminum trichloride in a generator to generate aluminum trichloride, the titanium tetrachloride and the aluminum trichloride are mixed and enter the feeding ring through a feeding and scabbing pipeline, a nitrogen purging pipe is attached to the titanium tetrachloride inlet pipeline valve and provides titanium dioxide particles or quartz sand to form scabbing gas by taking nitrogen as carrier gas, the device is used for scarifying the feeding ring, a first cooling section air film, a second cooling section air film and a first scarifying material inlet are arranged on the cooling section, a second scarifying material inlet is arranged on the cooling guide pipe, chlorine or nitrogen is introduced into the cooling section through the first cooling section air film and the second cooling section air film for preventing scarification, rock salt or quartz sand is introduced into the cooling section and the cooling guide pipe through the chlorine as carrier gas for scarifying the cooling section and the cooling guide pipe through the first scarifying material inlet and the second scarifying material inlet, the quartz sand, titanium dioxide particles and the scarified scabs do not enter a scarifying tank, the quartz sand, the titanium dioxide particles and the scarifying agent are separated through a bag filter and then independently enter the scarifying material storage tank, and the scarifying tank is used for collecting titanium dioxide;

first toluene rifle cooling water pipeline, second xylene rifle cooling water pipeline set up on the toluene rifle for control the temperature to the toluene rifle, cooling water pipeline 7, stove tail cooling water pipeline set up respectively on oxidation reactor's cooling zone and cooling conduit 19 in the stove, and oxidation reactor's inner wall adopts the cover of pressing from both sides to keep apart, and the cooling water gets into to press from both sides in the cover, controls oxidation reactor's temperature.

2. An oxidation reactor scar prevention and removal system as set forth in claim 1 wherein: the rock salt is sodium chloride, and the cooling water is desalted water; the axial direction of the feeding and scaring pipeline and the radial direction of the feeding ring form a 75-degree angle, the feeding ring comprises a gas distribution ring and a jet ring, the gas distribution ring is sleeved on the jet ring, and the gas distribution ring is communicated with the feeding and scaring pipeline; the inner diameter of the jet ring is 186mm, the width of the jet ring is 120mm, 24 circular openings are uniformly distributed on the circumference, and the diameter of each circular opening is 12.7 mm; the inner diameter of the gas distribution ring is 306mm, the width of the gas distribution ring is 120mm, 16 slit-shaped openings are uniformly distributed on the circumference, the width of each slit-shaped opening is 10mm, and the length of each slit-shaped opening is 100 mm.

3. A method for preventing and removing scars using the scar prevention and removal system of the oxidation reactor of claim 1, comprising the steps of:

step 1, cooling, namely opening a first cooling section air film and a second cooling section air film, introducing anti-scar chlorine or nitrogen, preheating the anti-scar chlorine or nitrogen to 50-80 ℃, forming an air curtain by the anti-scar chlorine or nitrogen to uniformly cover a reaction section of an oxidation reactor, and introducing 25 ℃ cooling water into a first toluene gun cooling water pipeline, a second xylene gun cooling water pipeline, a furnace cooling water pipeline and a furnace tail cooling water pipeline;

step 2, raising the temperature and feeding materials, wherein the materials in the oxidation reactor are titanium tetrachloride gas and hot oxygen gas which are preheated to 400-500 ℃ by a titanium tetrachloride preheater, the hot oxygen gas is preheated to 800-900 ℃ by an oxygen preheater and is combusted and heated to 1800 ℃ by toluene sprayed by a toluene gun in the oxidation reactor, and the adding ratio of the titanium tetrachloride gas to the hot oxygen gas is 4: 1-6: 1;

reacting aluminum powder or aluminum particles with chlorine in an aluminum trichloride generator to generate a crystal form conversion agent aluminum trichloride, controlling the adding amount of the aluminum powder or the aluminum particles to ensure that the content of aluminum oxide in a titanium dioxide primary product is 0.7-1.2%, wherein the aluminum powder or the aluminum particles are a rutile crystal form conversion agent, preparing a potassium chloride solution with qualified concentration as a nucleating agent, and reacting titanium tetrachloride gas with oxygen in a reaction section of an oxidation reactor to generate titanium dioxide and chlorine;

step 3, continuously adding rock salt into the oxidation reactor in the production operation of the oxidation reactor, wherein the adding amount of the rock salt is determined according to the inlet temperature of the bag filter, so that the inlet temperature of the bag filter is kept at 160-200 ℃, and the rock salt is respectively added into a first scaring material inlet at the tail section of the oxidation reactor and a second scaring material inlet at the inlet of the cooling conduit through chlorine as carrier gas;

step 4, scabbing treatment, wherein when the pressure difference between a furnace head and a furnace tail is above a threshold value in the operation process of an oxidation reactor, the situation that more scabs are formed in the oxidation reactor and the safety production is influenced is shown, the thermal condition state of an oxygen preheater is kept, oxygen is continuously introduced, a potassium chloride inlet pipe is sequentially closed, potassium chloride solution is stopped being introduced, aluminum powder or aluminum particles are stopped being introduced, chlorine is continuously introduced into an aluminum trichloride generator, the thermal condition state is kept, a titanium tetrachloride inlet pipeline valve is closed, the introduction of titanium tetrachloride gas and aluminum trichloride mixed gas is stopped, a nitrogen purging pipe is opened, the titanium tetrachloride and aluminum trichloride mixed gas is switched to nitrogen, the titanium tetrachloride preheater is kept in the thermal condition state, a feeding pipe and a scabbing pipeline are opened, titanium dioxide particles or quartz sand are introduced into a feeding ring, scabbing treatment is carried out, and the scabbing rock salt at a first scabbing inlet and a second scabbing inlet is switched to titanium dioxide particles, removing scars at the tail section of the oxidation reactor and in the cooling guide pipe by utilizing the physical friction of titanium dioxide powder or quartz sand; quartz sand, titanium dioxide particles and the removed scabs do not enter a pulping tank, the mixture is subjected to gas-solid separation through a bag filter and then independently enters a scab material storage tank, and the scab material storage tank is treated through a corresponding recovery process;

and 5, after the pressure difference of the oxidation reactor system is reduced to be below a threshold value, stopping the quartz sand or titanium dioxide particles from entering the oxidation reactor, closing the scab material storage tank, opening the pulping tank, opening a titanium tetrachloride inlet pipeline valve, introducing titanium tetrachloride gas, closing a nitrogen purging pipe, ensuring smooth introduction of chlorine gas by the aluminum trichloride generator, simultaneously introducing aluminum powder or aluminum particles, introducing the generated aluminum trichloride into the oxidation reactor, introducing a potassium chloride solution into the oxidation reactor, opening a first scab material inlet and a second scab material inlet, and introducing rock salt.

4. The method according to claim 3, characterized in that the titanium tetrachloride gas and the hot oxygen gas of the step 2 are added preferably at a ratio of 4:1, 5:1 or 6: 1.

5. A process according to claim 3, characterized in that the alumina content in the titanium dioxide preform of step 2 is preferably 0.7%, 1.0% or 1.2%.

6. The method according to claim 3, characterized in that the bag filter inlet temperature of step 3 is preferably maintained at 170 ℃, 180 ℃ or 190 ℃.

7. The method according to claim 3, characterized in that the threshold value of step 4 is 30-40 kpa.

8. The method according to claim 7, characterized in that the threshold value of step 4 is 30kpa, 35kpa or 40 kpa.

9. The method according to claim 3, wherein in the step 2, the flow rate, the temperature, the density and the mole fraction of the titanium tetrachloride gas and the hot oxygen gas are optimized to obtain the best reaction effect and reduce the probability of scabbing, and the specific steps are as follows:

step 2.1, data are collected, and gas velocities v on different sections of the oxidation reactor are obtained_iTitanium tetrachloride gas relative mole fraction c_iDensity of preheated titanium tetrachloride gas

Step 2.2, establishing an index model,

distribution unevenness M_fExpressing the velocity profile, M, at each cross-section in the oxidation reactor_fThe smaller, the more uniform the gas velocity distribution is indicated,

wherein v is_iGas velocity for the ith cross section;

mixing unevenness M_hThe variance, M, of the relative concentration of titanium tetrachloride gas on the inner cross section of the oxidation reactor is expressed_hThe smaller the value of (A) is, the more uniform the mixing of the gases is indicated,

wherein, c_iIs the relative mole fraction of titanium tetrachloride gas in the ith cross section,

the closer the momentum ratio N is to 1, the more balanced the two streams have on mixing,

wherein the content of the first and second substances,

jet depth L_sWhich indicates the jet penetration capacity, and the mixing distribution of the jet flow and the axial flow, which is mainly related to the jet penetration capacity, L_sA larger jet indicates a larger influence of the jet,

g is the acceleration of gravity; d_pJet particle diameter; μ is the axial gas flow viscosity;

step 2.3, establishing an evaluation model, wherein P is L_s-M_f-M_h- | N-1|, P is an evaluation value, which indicates the condition of the mixed reaction of the two gases in the oxidation reactor, and the larger the value, the better the condition of the mixed reaction;

and 2.4, calculating to obtain the maximum evaluation value by adjusting the gas flow rate, the temperature, the density and the mole fraction, and further obtaining the optimal parameter ratio.

10. The method according to claim 3, characterized in that the recovery process of step 4 comprises the following steps:

step 4.1, quartz sand is separated, the quartz sand is separated by a screening device, solid particles are separated by the separation device, and secondary damage to the quartz sand in the separation process is avoided; the quartz sand after separation and static dehydration is transmitted to a subsequent washing system; the separated titanium dioxide and water form slurry and enter the post-treatment process of titanium dioxide production;

step 4.2, washing the quartz sand, conveying the separated sand to a washer to wash the quartz sand, wherein a small amount of titanium dioxide base material is remained on the surface of the quartz sand separated by the separation equipment,

the washer comprises a sand washing tank, a stirrer, a discharging screw, a flushing device and a discharging controller, wherein sand separated from the separating device is conveyed into the sand washing tank by the conveyor, a screen is installed at the bottom of the sand washing tank and is connected with the flushing device, four flushing ports with adjustable heights are installed at the upper part of the sand washing tank, so that the quartz sand on the surface of the sand washing tank can be fully washed, after the upper part of the sand washing tank is flushed, the flushing device at the bottom of the sand washing tank flushes the quartz sand, the water quantity is automatically controlled through the flow and the actual process condition, and the washed quartz sand is accumulated in the sand washing tank;

the unloading controller controls the material level of the quartz sand in the sand washing tank, when the quartz sand layer reaches the material level, the unloading controller interrupts sand feeding, and simultaneously controls unloading spiral unloading, the sand is not completely unloaded during unloading, and the quartz sand layer with certain thickness is reserved at the bottom of the washing tank; the thickness of the sand layer is determined by the model of the washer, and the washing water of the quartz sand enters the quartz sand separation system as primary washing water and enters the subsequent working procedure for recycling;

step 4.3, drying the quartz sand, and conveying the wet quartz sand from the quartz sand washing system into a dryer through a conveyor, wherein the dryer comprises a rotatable cylinder, and a plurality of layers of heating pipes are arranged in the cylinder;

in the dryer, the wet quartz sand is in indirect contact with a drying medium with a certain temperature conveyed from the outside of a boundary area along with the rotation of the cylinder, the heat of the drying medium is transferred to the wet quartz sand in a convection mode, the moisture in the quartz sand is gasified and transferred to gas to be taken away, and the dried sand is moved to the rear end by the rotation of the dryer;

and 4.4, screening, discharging the quartz sand from a discharge rotary valve at the tail part of the dryer when the water content of the quartz sand is less than 0.3%, feeding the quartz sand into a dry sand bin, separating partial crushed sand from the dry quartz sand through a sand separator, returning the sand with the particle size of 0.9-1.5mm to a quartz sand feeding system, recycling, collecting and post-treating the part with the particle size of less than 0.9mm, and supplementing a part of new qualified sand into the system while separating fine sand to ensure the stability of the sand amount in the system.

Technical Field

The invention belongs to the field of titanium dioxide production, and particularly relates to a scar preventing and removing system and method for an oxidation reactor.

Background

The chlorination process for producing titanium dioxide has the advantages of short flow, high automation degree, small pollution and the like, and is an ideal method for producing rutile titanium dioxide, wherein the gas phase oxidation process is the core of the whole chlorination process for producing titanium dioxide. The oxidation reactor is also an important device in the whole oxidation process, the whole oxidation process work is developed around the oxidation reactor, and the main technical problem which plagues the oxidation reactor at present is the scab of the oxidation reactor, especially the scab of a titanium tetrachloride feeding ring, which causes the pressure of an oxidation reactor system to rise, and further causes the shutdown of the oxidation system, thereby affecting the productivity. The scab material is mainly titanium dioxide bond. The current scar prevention and removal schemes are porous wall air curtain scar prevention, mechanical scraper scar removal, quartz sand scar removal and rock salt single-point scar removal.

Disclosure of Invention

The present invention provides a scar preventing and removing system for an oxidation reactor and a method thereof for solving the above problems, which can prevent and remove the scar of the oxidation system by means of gas introduction and differential pressure scar forming under thermal conditions, optimize gas parameters so as to further prevent the probability of scar forming, and recycle quartz sand so as to realize cyclic utilization.

The technical scheme of the invention is as follows: a scar preventing and removing system of an oxidation reactor comprises the oxidation reactor and a scar preventing and removing device, wherein the oxidation reactor is provided with the scar preventing and removing device, and the scar preventing and removing device comprises a first cooling section air film, a second cooling section air film, a first scar material inlet, a second scar material inlet, a first toluene gun water pipeline, a second xylene gun cooling water pipeline, a furnace tail cooling water pipeline, a feeding ring, a nitrogen purging pipe 10, a feeding and scarring pipeline, a hot oxygen inlet pipe, a potassium chloride inlet pipe, a titanium tetrachloride preheater, an oxygen preheater, an aluminum trichloride generator, a potassium chloride solution storage tank, a scar material storage tank, a cooling conduit, a bag filter, a pulping tank, a chlorine pipeline, a toluene gun and a titanium tetrachloride inlet pipeline valve;

the oxidation reactor is divided into a combustion section, a reaction section and a cooling section, a toluene gun is communicated with a hot oxygen inlet pipe at the combustion section, toluene and oxygen are mixed and combusted, oxygen at the hot oxygen inlet pipe is preheated by an oxygen preheater, potassium chloride in a potassium chloride solution storage tank enters the reaction section of the oxidation reactor through the potassium chloride inlet pipe to form a nucleating agent, a temperature measuring port is arranged on the reaction section of the oxidation reactor to monitor the reaction temperature, a feeding ring is arranged at the tail section of the reaction section, titanium tetrachloride passing through a titanium tetrachloride inlet pipeline valve is preheated in the titanium tetrachloride preheater, chlorine in a chlorine pipeline reacts with aluminum powder or aluminum particle aluminum trichloride in a generator to generate aluminum trichloride, the titanium tetrachloride and the aluminum trichloride are mixed and enter the feeding ring through a feeding and scabbing pipeline, a nitrogen purging pipe is attached to the titanium tetrachloride inlet pipeline valve and provides titanium dioxide particles or quartz sand to form scabbing gas by taking nitrogen as carrier gas, the device is used for scarifying the feeding ring, a first cooling section air film, a second cooling section air film and a first scarifying material inlet are arranged on the cooling section, a second scarifying material inlet is arranged on the cooling guide pipe, chlorine or nitrogen is introduced into the cooling section through the first cooling section air film and the second cooling section air film for preventing scarification, rock salt or quartz sand is introduced into the cooling section and the cooling guide pipe through the chlorine as carrier gas for scarifying the cooling section and the cooling guide pipe through the first scarifying material inlet and the second scarifying material inlet, the quartz sand, titanium dioxide particles and the scarified scabs do not enter a scarifying tank, the quartz sand, the titanium dioxide particles and the scarifying agent are separated through a bag filter and then independently enter the scarifying material storage tank, and the scarifying tank is used for collecting titanium dioxide;

first toluene rifle cooling water pipeline, second xylene rifle cooling water pipeline set up on the toluene rifle for control the temperature to the toluene rifle, cooling water pipeline 7, stove tail cooling water pipeline set up respectively on oxidation reactor's cooling zone and cooling conduit 19 in the stove, and oxidation reactor's inner wall adopts the cover of pressing from both sides to keep apart, and the cooling water gets into to press from both sides in the cover, controls oxidation reactor's temperature.

A scar preventing and removing method for an oxidation reactor comprises the following steps:

step 1, cooling, namely opening a first cooling section air film and a second cooling section air film, introducing anti-scar chlorine or nitrogen, preheating the anti-scar chlorine or nitrogen to 50-80 ℃, forming an air curtain by the anti-scar chlorine or nitrogen to uniformly cover a reaction section of an oxidation reactor, and introducing 25 ℃ cooling water into a first toluene gun cooling water pipeline, a second xylene gun cooling water pipeline, a furnace cooling water pipeline and a furnace tail cooling water pipeline;

step 2, raising the temperature and feeding materials, wherein the materials in the oxidation reactor are titanium tetrachloride gas and hot oxygen gas which are preheated to 400-500 ℃ by a titanium tetrachloride preheater, the hot oxygen gas is preheated to 800-900 ℃ by an oxygen preheater and is combusted and heated to 1800 ℃ by toluene sprayed by a toluene gun in the oxidation reactor, and the adding ratio of the titanium tetrachloride gas to the hot oxygen gas is 4: 1-6: 1;

reacting aluminum powder or aluminum particles with chlorine in an aluminum trichloride generator to generate a crystal form conversion agent aluminum trichloride, controlling the adding amount of the aluminum powder or the aluminum particles to ensure that the content of aluminum oxide in a titanium dioxide primary product is 0.7-1.2%, wherein the aluminum powder or the aluminum particles are a rutile crystal form conversion agent, preparing a potassium chloride solution with qualified concentration as a nucleating agent, and reacting titanium tetrachloride gas with oxygen in a reaction section of an oxidation reactor to generate titanium dioxide and chlorine;

step 3, continuously adding rock salt into the oxidation reactor in the production operation of the oxidation reactor, wherein the adding amount of the rock salt is determined according to the inlet temperature of the bag filter, so that the inlet temperature of the bag filter is kept at 160-200 ℃, and the rock salt is respectively added into a first scaring material inlet at the tail section of the oxidation reactor and a second scaring material inlet at the inlet of the cooling conduit through chlorine as carrier gas;

step 4, scabbing treatment, wherein when the pressure difference between a furnace head and a furnace tail is above a threshold value in the operation process of an oxidation reactor, the situation that more scabs are formed in the oxidation reactor and the safety production is influenced is shown, the thermal condition state of an oxygen preheater is kept, oxygen is continuously introduced, a potassium chloride inlet pipe is sequentially closed, potassium chloride solution is stopped being introduced, aluminum powder or aluminum particles are stopped being introduced, chlorine is continuously introduced into an aluminum trichloride generator, the thermal condition state is kept, a titanium tetrachloride inlet pipeline valve is closed, the introduction of titanium tetrachloride gas and aluminum trichloride mixed gas is stopped, a nitrogen purging pipe is opened, the titanium tetrachloride and aluminum trichloride mixed gas is switched to nitrogen, the titanium tetrachloride preheater is kept in the thermal condition state, a feeding pipe and a scabbing pipeline are opened, titanium dioxide particles or quartz sand are introduced into a feeding ring, scabbing treatment is carried out, and the scabbing rock salt at a first scabbing inlet and a second scabbing inlet is switched to titanium dioxide particles, removing scars at the tail section of the oxidation reactor and in the cooling guide pipe by utilizing the physical friction of titanium dioxide powder or quartz sand; quartz sand, titanium dioxide particles and the removed scabs do not enter a pulping tank, the mixture is subjected to gas-solid separation through a bag filter and then independently enters a scab material storage tank, and the scab material storage tank is treated through a corresponding recovery process;

and 5, after the pressure difference of the oxidation reactor system is reduced to be below a threshold value, stopping the quartz sand or titanium dioxide particles from entering the oxidation reactor, closing the scab material storage tank, opening the pulping tank, opening a titanium tetrachloride inlet pipeline valve, introducing titanium tetrachloride gas, closing a nitrogen purging pipe, ensuring smooth introduction of chlorine gas by the aluminum trichloride generator, simultaneously introducing aluminum powder or aluminum particles, introducing the generated aluminum trichloride into the oxidation reactor, introducing a potassium chloride solution into the oxidation reactor, opening a first scab material inlet and a second scab material inlet, and introducing rock salt.

The invention has the beneficial effects that:

1) the invention prevents and removes the scab of the oxidation system, especially the scab at the feeding ring of the titanium tetrachloride and the cooling conduit of the oxidation furnace, controls the pressure difference of the system in a reasonable range, removes the scab under the condition of thermal conditions, and does not extinguish the preheater and the oxidation reactor during the scab removing. The number of times of stopping due to scabbing of the oxidation system is reduced, the disassembly and inspection of the oxidation reactor due to the scabbing are reduced, and the operation period of the oxidation system is prolonged. The utilization efficiency of the oxidation system is improved.

2) In the production process, chlorine or nitrogen is introduced into the cooling section to form an air curtain so as to prevent scabbing;

3) after the pressure difference reaches a certain degree, judging that the scabbing condition is serious, and adding titanium dioxide particles or quartz sand into the feeding and scabbing pipeline, the first scabbing inlet and the second scabbing inlet to scab, so that the prevention and control integration is realized;

4) the invention provides an effective solution for preventing and removing scars under the conditions of hot working conditions and the operating process of an oxidation reactor, and has the combination of scar prevention and scar removal. The scar removing method is mainly characterized in that rock salt, titanium dioxide powdery particles and quartz sand are used for scar removing at a titanium tetrachloride feeding ring of an oxidation reactor, a tail section of the oxidation reactor and a cooling guide pipe.

5) The arrangement of the feeding ring structure and the arrangement that the axial direction of the feeding pipeline forms 75 degrees with the radial direction of the feeding ring, the angle ensures that a low-speed area is almost not present near the inlet, and fluid can pass through the feeding ring at a higher speed, so that the probability of scabbing can be greatly reduced;

6) the gas flow rate, temperature, density and mole fraction are optimized to obtain the best reaction effect and reduce the probability of scabbing.

Drawings

FIG. 1 is a schematic diagram of the system components of the present invention;

FIG. 2 is a view showing the structure of an oxidation reactor according to the present invention;

FIG. 3 is a flow chart of the scar prevention and removal method of the present invention;

wherein, 1: a first cooling section gas film; 2: a second cooling section gas film; 3 a first scab inlet; 4: a second scaring material inlet; 5: a first toluene gun cooling water conduit; 6: a second xylene gun cooling water conduit; 7: a furnace cooling water conduit; 8: a furnace tail cooling water pipeline; 9: a feeding ring; 10: a nitrogen purge tube; 11: feeding and scarfing piping; 12: a hot oxygen inlet pipe; 13: a potassium chloride inlet pipe; 14: a titanium tetrachloride preheater; 15: an oxygen preheater; 16: an aluminum trichloride generator; 17: a potassium chloride solution storage tank; 18: a scar material storage tank; 19: a cooling conduit; 20: a bag filter; 21: a pulping tank; 22: a chlorine pipeline; 23: a toluene gun; 24: an oxidation reactor; 25: titanium tetrachloride inlet pipe valve.

Detailed Description

The invention is further described with reference to the following figures and examples.

Embodiments of the present invention are illustrated with reference to fig. 1-3.

A scar preventing and removing system of an oxidation reactor comprises an oxidation reactor 24 and a scar preventing and removing device, wherein the oxidation reactor 24 is provided with the scar preventing and removing device, and the scar preventing and removing device comprises a first cooling section air film 1, a second cooling section air film 2, a first scar material inlet 3, a second scar material inlet 4, a first toluene gun cooling water pipeline 5, a second xylene gun cooling water pipeline 6, a furnace cooling water pipeline 7, a furnace tail cooling water pipeline 8, a feeding ring 9, a nitrogen purging pipe 10, a feeding and scar removing pipeline 11, a hot oxygen inlet pipe 12, a potassium chloride inlet pipe 13, a titanium tetrachloride preheater 14, an oxygen preheater 15, an aluminum trichloride generator 16, a potassium chloride solution storage tank 17, a scar material storage tank 18, a cooling conduit 19, a bag filter 20, a pulping tank 21, a chlorine pipeline 22, a toluene gun 23 and a titanium tetrachloride inlet pipeline valve 25;

the oxidation reactor 24 is divided into a combustion section, a reaction section and a cooling section, a toluene gun 23 is communicated with a hot oxygen inlet pipe 12 at the combustion section, toluene and oxygen are mixed and combusted, the oxygen of the hot oxygen inlet pipe 12 is preheated by an oxygen preheater 15, potassium chloride in a potassium chloride solution storage tank 17 enters the reaction section of the oxidation reactor 24 through a potassium chloride inlet pipe 13 to form a nucleating agent, a temperature measuring port is arranged on the reaction section of the oxidation reactor 24 to monitor the reaction temperature, a feed ring 9 is arranged at the tail section of the reaction section, titanium tetrachloride passing through a titanium tetrachloride inlet pipeline valve 25 is preheated in a titanium tetrachloride preheater 14, chlorine in a chlorine pipeline 22 reacts with aluminum powder or aluminum particle aluminum trichloride generator 16 to generate aluminum trichloride, the titanium tetrachloride is mixed with the aluminum trichloride, the mixture enters the feed ring 9 through a feeding and scabbing pipeline 11, a nitrogen purging pipe 10 is attached to the titanium tetrachloride inlet pipeline valve 25, titanium dioxide particles or quartz sand are provided, nitrogen is used as carrier gas to form scabbing gas, the scabbing gas is used for scabbing and cleaning a feeding ring 9, a first cooling section air film 1, a second cooling section air film 2 and a first scabbing material inlet 3 are arranged on a cooling section, a second scabbing material inlet 4 is arranged on a cooling guide pipe 19, chlorine or nitrogen is led into the cooling section through the first cooling section air film 1 and the second cooling section air film 2 and is used for preventing scabbing, rock salt or quartz sand is led into the cooling section and the cooling guide pipe 19 through the chlorine which is used as carrier gas in the first scabbing material inlet 3 and the second scabbing material inlet 4 and is used for scabbing and cleaning the cooling section and the cooling guide pipe 19, the quartz sand, the titanium dioxide particles and the scabs which are removed do not enter a scabbing tank 21, the quartz sand, the titanium dioxide particles and the scabs which are removed are subjected to gas-solid separation through a bag filter 20 and then independently;

the first toluene gun cooling water pipeline 5 and the second toluene gun cooling water pipeline 6 are arranged on the toluene gun 23 and used for controlling the temperature of the toluene gun 23, the furnace cooling water pipeline 7 and the furnace tail cooling water pipeline 8 are respectively arranged on the cooling section of the oxidation reactor 24 and the cooling conduit 19, the inner wall of the oxidation reactor 24 is isolated by a jacket, cooling water enters the jacket to control the temperature of the oxidation reactor 24,

wherein the rock salt is sodium chloride,

wherein the cooling water is desalted water

A scar preventing and removing method for an oxidation reactor comprises the following steps: the method comprises the following steps:

step 1, cooling, namely opening a first cooling section air film 1 and a second cooling section air film 2, introducing anti-scar chlorine or nitrogen, preheating the anti-scar chlorine or nitrogen to 50-80 ℃, forming an air curtain by the anti-scar chlorine or nitrogen to uniformly cover a reaction section of an oxidation reactor 24, and introducing 25 ℃ cooling water into a first toluene gun cooling water pipeline 5, a second xylene gun cooling water pipeline 6, a furnace cooling water pipeline 7 and a furnace tail cooling water pipeline 8;

the scar prevention mode is air film scar prevention and cooling water temperature reduction scar prevention. Two air curtains are used for protection, and the air curtain gas is chlorine or nitrogen, mainly chlorine.

The cooling water is separated from the inner wall of the oxidation furnace by a jacket, and the cooling water plays roles in cooling, preventing overhigh wall temperature and slowing down scab.

Step 2, raising the temperature and feeding materials, wherein the materials in the oxidation reactor 24 are titanium tetrachloride and hot oxygen which are preheated to 400-500 ℃ by a titanium tetrachloride preheater 14, the hot oxygen is preheated to 800-900 ℃ by an oxygen preheater 15, and is heated to 1800 ℃ by burning toluene sprayed by a toluene gun 23 in the oxidation reactor 24, and the adding ratio of the titanium tetrachloride to the hot oxygen is 4: 1-6: 1;

aluminum powder or aluminum particles and chlorine react in an aluminum trichloride generator 16 to generate a crystal form conversion agent aluminum trichloride, the adding amount of the aluminum powder or aluminum particles is controlled to ensure that the content of aluminum oxide in a titanium dioxide primary product is 0.7-1.2%, the aluminum powder or aluminum particles are a rutile crystal form conversion agent, a potassium chloride solution with qualified concentration is prepared to be used as a nucleating agent, and titanium tetrachloride and oxygen react in a reaction section of an oxidation reactor 24 to generate titanium dioxide and chlorine;

in the feeding production and reaction processes, titanium dioxide is easy to adhere to the wall of the oxidation reactor, and a soft scar layer formed on the surface of the wall of the reactor is gradually thickened and hardened without effective scar-removing and preventing measures, so that the scar layer blocks the oxidation reactor, particularly the feeding ring 9, the normal reaction is influenced finally, and the scar of the oxidation reactor is aggravated by adding aluminum.

The materials in the oxidation reactor are mainly titanium tetrachloride preheated to 400-500 ℃ by a titanium tetrachloride preheater 14, preheated to 800-900 ℃ by an oxygen preheater 15, and continuously heated to 1800 ℃ by burning toluene injected by a toluene gun in the oxidation reactor. Aluminum powder or aluminum particles and chlorine react in an aluminum trichloride generator 16 to generate a crystal form conversion agent aluminum trichloride and a prepared nucleating agent potassium chloride solution with qualified concentration. The adding amount of aluminum powder or aluminum particles is strictly controlled. The aluminum can prevent the scab caused by excessive addition. The adding amount of the aluminum powder or the aluminum particles is controlled to be 0.7-1.2 percent of the content of the aluminum oxide in the titanium dioxide primary product. The adding ratio of the titanium tetrachloride to the hot oxygen is 4: 1-6: 1.

Step 3, continuously adding rock salt into the oxidation reactor 24 in the production operation of the oxidation reactor 24, wherein the adding amount of the rock salt is determined according to the inlet temperature of the bag filter 20, the inlet temperature of the bag filter 20 is kept at 160-;

the main component of rock salt is sodium chloride, and rock salt particles can be removed from titanium dioxide by water washing in the subsequent post-treatment process. The quality of the titanium dioxide is not affected. Rock salt is sprayed at the tail section of the oxidation reactor, and rock salt spraying points are added at the inlet of the cooling guide pipe, so that scabs in the cooling guide pipe can be effectively removed. The rock salt is added according to the inlet temperature of the bag filter, so that the inlet temperature of the bag filter is kept at 160-200 ℃.

Step 4, scabbing treatment, wherein when the pressure difference between the furnace head and the furnace tail in the operation process of the oxidation reactor 24 is above a threshold value, the situation that more scabs are formed in the oxidation reactor 24 and the safe production is influenced is shown, the thermal condition state of the oxygen preheater 15 is kept, oxygen is continuously introduced, the potassium chloride inlet pipe 13 is sequentially closed, the introduction of potassium chloride solution is stopped, the introduction of aluminum powder or aluminum particles is stopped, the introduction of chlorine is continuously performed by the aluminum trichloride generator 16, the thermal condition state is kept, the titanium tetrachloride inlet pipeline valve 25 is closed, the introduction of the titanium tetrachloride and aluminum trichloride mixed gas is stopped, the nitrogen purging pipe 10 is opened, the titanium tetrachloride and aluminum trichloride mixed gas is switched to nitrogen, the titanium tetrachloride 14 is continuously kept in the thermal condition state, the feeding and scabbing pipelines 11 are simultaneously opened, titanium dioxide particles or quartz sand are introduced into the feeding ring 9 for scabbing cleaning, and the scabbing material salts at the first scabbing material inlet 3 and the second scabbing material inlet 4 are switched Removing scabs in the tail section of the oxidation reactor and the cooling guide pipe by utilizing the physical friction action of titanium dioxide powder or quartz sand; quartz sand, titanium dioxide particles and the removed scabs do not enter the pulping tank 21, the mixture is subjected to gas-solid separation through the bag filter 20 and then independently enters the scab material storage tank 18, and the scab material storage tank 18 is treated through a corresponding recovery process;

the powder particles are used as an optional mode for removing scars, and when the pressure difference of the system is large due to scars, the high value of the pressure difference is 30-40 kpa. The differential pressure tail oxidizes the pressure difference between the furnace head and the furnace tail of the furnace. Can remove scars under the conditions of no stopping and hot working. And mainly scabs at the feeding ring of the titanium tetrachloride.

The quartz sand or titanium dioxide particles are added after the titanium tetrachloride feed is stopped in the oxidation reactor but the system is maintained under thermal conditions. And a storage tank for collecting quartz sand, titanium dioxide particles and scab materials which are knocked off by a separate collecting device. Does not affect the product quality

And 5, after the system pressure difference of the oxidation reactor 24 is reduced to be below a threshold value, stopping the quartz sand or titanium dioxide particles from entering the oxidation reactor 24, closing the scab material storage tank 18, opening the pulping tank 21, opening the titanium tetrachloride inlet pipeline valve 23 to introduce titanium tetrachloride, closing the nitrogen purging pipe 10, ensuring that chlorine gas is introduced smoothly by the aluminum trichloride generator 16, simultaneously introducing aluminum powder or aluminum particles, introducing the generated aluminum trichloride into the oxidation reactor 24, introducing a potassium chloride solution into the oxidation reactor 24, opening the first scab material inlet 3 and the second scab material inlet 4, and introducing rock salt.

Wherein the addition ratio of the titanium tetrachloride and the hot oxygen in the step 2 is preferably 4:1, 5:1 or 6: 1;

wherein, the content of alumina in the titanium dioxide primary product in the step 2 is preferably 0.7%, 1.0% or 1.2%;

wherein the inlet temperature of the bag filter 20 of step 3 is preferably maintained at 170 ℃, 180 ℃ or 190 ℃;

wherein the threshold value of the step 4 is 30-40 kpa;

wherein the threshold value of the step 4 is 30kpa, 35kpa or 40 kpa.

The system and the method are characterized in that chlorine or nitrogen is introduced into a cooling section in the production process to form an air curtain so as to prevent the scab problem, after the pressure difference reaches a certain degree, the scab condition is judged to be serious, and titanium dioxide particles or quartz sand are added into a feeding and scab pipeline 11, a first scab inlet 3 and a second scab inlet 4 for scab, so that the prevention and control are integrated. The scar removing method is mainly characterized in that rock salt, titanium dioxide powdery particles and quartz sand are used for scar removing at a titanium tetrachloride feeding ring of an oxidation reactor, a tail section of the oxidation reactor and a cooling guide pipe.

Wherein the axial direction of the feeding and scarfing duct 11 is at 75 degrees to the radial direction of the feeding ring 8,

experiments show that when the mixed gas entering from the feeding and scabbing pipeline 11 at the feeding ring 8 in the tangential direction is mixed with the oxygen gas entering from the feeding ring 8 in the axial direction, when the mixed gas flow and the oxygen flow form jet flows at different angles, the flow of the flow field inside the oxidation reactor is influenced, and further, the scabbing in the oxidation reactor, the improvement of the yield and the quality of the titanium dioxide are greatly influenced, for example,

when the angle is 30 degrees, a large low-speed area of 1.28-2.56m/s exists near the inlet, so that the titanium dioxide stays for too long time to generate the scab phenomenon;

when the angle is 45 degrees, a large low-speed area of 1.06-2.11m/s exists near the inlet, and the area of the low-speed area is larger than that of 30 degrees, so that the phenomenon of scabbing caused by overlong retention time of titanium dioxide is more easily caused;

when the angle is 60 degrees, a low-speed area of 1.36-2.71ra/s exists near the inlet, but the area of the low-speed area is obviously reduced;

when the angle is 75 degrees, a low-speed area is almost not present near the inlet, and fluid can pass through at a higher speed, so that the scabbing probability can be greatly reduced, and therefore when the intersection angle of the airflow of the oxidation reactor is 75 degrees, the flow of a flow field is facilitated, and the scabbing probability is also facilitated to be reduced.

Wherein the feeding ring 9 comprises a gas distribution ring and a jet ring, the gas distribution ring is sleeved on the jet ring and is communicated with the feeding and scabbing pipeline 11,

the inner diameter of the jet ring is 186mm, the width is 120mm, 24 circular openings are uniformly distributed on the circumference, the diameter of each circular opening is 12.7mm,

the inner diameter of the gas distribution ring is 306mm, the width of the gas distribution ring is 120mm, 16 slit-shaped openings are uniformly distributed on the circumference, the width of each slit-shaped opening is 10mm, and the length of each slit-shaped opening is 100 mm;

the shape and the number of the openings of the jet ring and the body distribution ring structure determine the shape, the number of the jet strands and the jet speed of the jet, influence the gas mixing condition and finally determine the product quality.

In step 2, the gas flow rate, temperature, density and mole fraction are optimized to obtain the best reaction effect and reduce the probability of scabbing, and the method specifically comprises the following steps:

step 2.1, data are collected, and gas velocities v on different sections of the oxidation reactor are obtained_iTitanium tetrachloride gas relative mole fraction c_iDensity of preheated titanium tetrachloride gas

Density of oxygen after combustion heating and

velocity v of preheated titanium tetrachloride gas passing through circular opening of jet ring_sVelocity v of the heated oxygen through the jet ring_a；

Step 2.2, establishing an index model,

distribution unevenness M_fExpressing the velocity distribution on each section in the oxidation reactor,

wherein v is_iGas velocity for the ith cross section;is the average value of the overall speed of the oxidation reactor; n is the number of sections;

M_fsmaller indicates more uniform gas velocity distribution;

mixing unevenness M_hThe variance of the relative concentration of titanium tetrachloride gas on the cross section in the oxidation reactor is expressed,

wherein, c_iIs the relative mole fraction of titanium tetrachloride gas in the ith cross section,

is the average of the relative mole fractions of titanium tetrachloride gas, M, at all measurement points on the cross section_hThe smaller the value of (A) is, the more uniform the mixing of the gases is.

When the effect of mixing of gases was evaluated, it was considered that M was present_hWhen the gas content is less than or equal to 0.05, the gas is micro-uniformly mixed.

The closer the momentum ratio N is to 1, the more balanced the two streams have on mixing,

andthe density of the preheated titanium tetrachloride gas and the density of oxygen after combustion heating, d_sThe diameter of the circular opening of the jet ring,d_ais the inner diameter of the jet ring, v_sThe velocity v of the preheated titanium tetrachloride gas passing through the circular opening of the jet ring_aVelocity of oxygen through jet ring after heating for combustion

Jet depth L_sWhich indicates the jet penetration capacity, and the mixing distribution of the jet flow and the axial flow, which is mainly related to the jet penetration capacity, L_sA larger jet indicates a larger influence of the jet,

g is the acceleration of gravity; d_pJet particle diameter; mu is the viscosity of the axial gas flow,

step 2.3, establishing an evaluation model, wherein P is L_s-M_f-M_h- | N-1|, P is an evaluation value, which indicates the condition of the mixed reaction of the two gases in the oxidation reactor, and the larger the value, the better the condition of the mixed reaction;

and 2.4, calculating to obtain the maximum evaluation value by adjusting the gas flow rate, the temperature, the density and the mole fraction, and further obtaining the optimal parameter ratio.

The recovery process of step 4 comprises the following steps:

step 4.1, quartz sand is separated, the quartz sand is separated by a screening device, solid particles are separated by the separation device, and secondary damage to the quartz sand in the separation process is avoided; the quartz sand after separation and static dehydration is transmitted to a subsequent washing system; the separated titanium dioxide and water form slurry and enter the post-treatment process of titanium dioxide production;

step 4.2, washing the quartz sand, conveying the separated sand to a washer to wash the quartz sand, wherein a small amount of titanium dioxide base material is remained on the surface of the quartz sand separated by the separation equipment,

the washer comprises a sand washing tank, a stirrer, a discharging screw, a flushing device and a discharging controller, wherein sand separated from the separating device is conveyed into the sand washing tank by the conveyor, a screen is installed at the bottom of the sand washing tank and is connected with the flushing device, four flushing ports with adjustable heights are installed at the upper part of the sand washing tank, so that the quartz sand on the surface of the sand washing tank can be fully washed, after the upper part of the sand washing tank is flushed, the flushing device at the bottom of the sand washing tank flushes the quartz sand, the water quantity is automatically controlled through the flow and the actual process condition, and the washed quartz sand is accumulated in the sand washing tank;

the unloading controller controls the material level of the quartz sand in the sand washing tank, when the quartz sand layer reaches the material level, the unloading controller interrupts sand feeding, and simultaneously controls unloading spiral unloading, the sand is not completely unloaded during unloading, and the quartz sand layer with certain thickness is reserved at the bottom of the washing tank; the thickness of the sand layer is determined by the model of the washer, and the washing water of the quartz sand enters the quartz sand separation system as primary washing water and enters the subsequent working procedure for recycling;

step 4.3, drying the quartz sand, and conveying the wet quartz sand from the quartz sand washing system into a dryer through a conveyor, wherein the dryer comprises a rotatable cylinder, and a plurality of layers of heating pipes are arranged in the cylinder;

in the dryer, the wet quartz sand is in indirect contact with a drying medium with a certain temperature conveyed from the outside of a boundary area along with the rotation of the cylinder, the heat of the drying medium is transferred to the wet quartz sand in a convection mode, the moisture in the quartz sand is gasified and transferred to gas to be taken away, and the dried sand is moved to the rear end by the rotation of the dryer;

and 4.4, screening, discharging the quartz sand from a discharge rotary valve at the tail part of the dryer when the water content of the quartz sand is less than 0.3%, feeding the quartz sand into a dry sand bin, separating partial crushed sand from the dry quartz sand through a sand separator, returning the sand with the particle size of 0.9-1.5mm to a quartz sand feeding system, recycling, collecting and post-treating the part with the particle size of less than 0.9mm, and supplementing a part of new qualified sand into the system while separating fine sand to ensure the stability of the sand amount in the system.

The above-described embodiment merely represents one embodiment of the present invention, but is not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.