A device and process for continuously preparing titanium oxychloride solution

Abstract

The present invention belongs to the field of chemical industry, and specifically relates to a device and process for continuously preparing titanium oxychloride solution. The device comprises: a titanium tetrachloride flowmeter, a venturi mixer, a pure water flowmeter, a falling film absorber, a hydrochloric acid absorption tower, a U-shaped tube, a heat exchanger, a liquid preparation circulation pump, a liquid preparation circulation tank, an absorption circulation pump, an exhaust fan, a hydrochloric acid circulation tank, and a hydrochloric acid circulation pump. The device and process can continuously produce and prepare titanium oxychloride solution with adjustable concentration and adjustable temperature, and can remove the reaction heat generated by the continuous mixing reaction and avoid boiling caused by a large amount of heat release. Since the whole system of the device operates at a slight negative pressure, there is no safety hazard of gas leakage. The device can continuously suck and transport titanium tetrachloride at a measured negative pressure, which is safe and reliable.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and in particular relates to a device and a process for continuously preparing titanium oxychloride solution. Background Art

[0002] Titanium tetrachloride is an important raw material for titanium sponge and titanium-containing compounds. Most of titanium tetrachloride is used to produce titanium dioxide and pigments. At room temperature, titanium tetrachloride is a colorless liquid. When exposed to air, it reacts with water in the air to produce a large amount of white smoke and a mixture of hydrated titanium dioxide and hydrochloric acid droplets. Titanium tetrachloride hydrolyzes at a certain temperature and water content to produce titanium dichloride. The chemical reaction equation is as follows:

[0003] TiCl 4 + H 2 O = TiOCl 2 + 2HCl.

[0004] Titanium tetrachloride undergoes irreversible hydrolysis reaction at high temperature and in excess water to generate hydrated titanium dioxide. Usually, when preparing titanium dioxide solution, it is undesirable to have excessive hydrolysis to generate titanium dioxide as a side reaction. The chemical reaction equation of excessive hydrolysis is as follows:

[0005] TiCl 4 + 3H 2 O = TiO 2 ·H 2 O + 4HCl.

[0006] In the electronic materials, nano-grade titanium dioxide, pearlescent effect materials and other industries, titanium tetrachloride is often prepared into a certain concentration of titanium tetrachloride solution for use in the next process. The existing titanium tetrachloride solution preparation equipment is mostly composed of a reactor, cooling water, absorption tower, etc. The existing preparation method is generally to first add the measured process water to the reactor, slowly add the measured titanium tetrachloride while stirring, and at the same time pass cooling water into the jacket of the reactor, and the tail gas of the reactor is absorbed by the absorption tower. Since the titanium tetrachloride solution is not just a simple physical mixing and dilution of titanium tetrachloride and water, it involves a complex hydrolysis chemical reaction. Therefore, different solution concentrations and temperature controls during the preparation process will cause different degrees of hydrolysis of titanium tetrachloride. The titanium tetrachloride preparation process releases a large amount of chemical reaction heat, and a large amount of hydrochloric acid mist is generated and escaped. The existing preparation methods are mostly intermittent operations, and the concentration gradient changes greatly, resulting in an increase in temperature during the preparation process, which is easy to form local boiling; moreover, the existing preparation equipment cannot dispose of the escaped gas in time, which is easy to cause gas leakage, thereby polluting the environment and interfering with the preparation process.

[0007] For example, Chinese patent document CN2923668Y discloses a titanium tetrachloride dilution complete set. The device consists of a titanium tetrachloride metering tank, a vacuum unit, a mixing nozzle, a titanium tetrachloride preparation tank, and a falling film absorption system. The device uses a vacuum unit to intermittently suck titanium liquid into a metering tank, and then mixes it with process water that is pre-dosed. The device operates intermittently and cannot achieve continuous operation. Each time the preparation begins, a small amount of concentrated titanium tetrachloride liquid reacts with a large amount of water, and the prepared solution has a low initial concentration, which is prone to irreversible over-hydrolysis reaction, generating titanium dioxide, affecting quality and causing waste. The solution concentration gradient changes greatly during the preparation process of the device, which is not conducive to quality control.

[0008] Another example: Chinese patent document CN206676368U discloses a production device for titanium oxychloride solution, which consists of a liquid storage tank, a reactor, a buffer tank and a vacuum pump. The device uses a vacuum pump to suck titanium tetrachloride into the reactor, and the titanium tetrachloride liquid reacts with the water pre-added in the reactor. The device operates intermittently and cannot produce continuously. Each time the preparation begins, a small amount of pure titanium tetrachloride liquid reacts with a large amount of water. The initial concentration of the prepared solution is low, and irreversible hydrolysis reaction is prone to occur, resulting in a large amount of titanium dioxide, which affects the quality and causes waste. The solution concentration gradient changes greatly during the preparation process of the device, which is not conducive to quality control. If the device is not properly controlled, hydrochloric acid will enter the vacuum pump and easily damage the equipment.

[0009] Another example: Chinese patent document CN102764601A discloses a titanium tetrachloride aqueous solution preparation device and process. The device consists of a jet vacuum pump, a graphite heat exchanger, a titanium tetrachloride mixing tank, an acid mist absorption tower, etc. The device and process are intermittent operations and cannot achieve continuous production. There is no gas escape channel between the jet vacuum pump and the heat exchanger of the device, and the hydrogen chloride gas escaped during the preparation process is brought into the heat exchanger, which affects the heat exchange effect.

[0010] In summary, the existing preparation devices and methods of titanium oxychloride solution have the following problems: first, continuous production cannot be achieved; second, there are risks of excessive hydrolysis side reactions, uneven concentrations and local boiling; third, it is difficult to measure and transfer titanium tetrachloride liquid; and fourth, there is a risk of gas leakage and environmental pollution. Summary of the invention

[0011] The first technical problem to be solved by the present invention is the problem that titanium oxychloride solution cannot be prepared in continuous production.

[0012] The second technical problem to be solved by the present invention is to reduce the side reaction of excessive hydrolysis, the problem of uneven concentration of titanium dichloride solution and the problem of violent boiling caused by the inability to remove a large amount of heat in time during the preparation process.

[0013] The third technical problem to be solved by the present invention is the difficulty in metering and transferring titanium tetrachloride liquid.

[0014] The fourth technical problem to be solved by the present invention is the problem of environmental pollution caused by gas leakage during the preparation of titanium oxychloride solution.

[0015] The object of the present invention is to provide a device and process for continuously preparing a titanium dichloride solution, which can not only continuously generate a titanium dichloride solution with a stable concentration and a stable temperature, but also continuously carry out a mixing reaction and remove the reaction heat, continuously recover the hydrochloric acid escaped from the reaction, and continuously extract titanium tetrachloride under negative pressure according to measurement.

[0016] The present invention is achieved through the following technical solutions:

[0017] In a first aspect, the present invention provides a device for continuously preparing titanium oxychloride solution, comprising: a titanium tetrachloride flowmeter, a venturi mixer, a pure water flowmeter, a falling film absorber, a hydrochloric acid absorption tower, a heat exchanger, a liquid preparation circulation pump, a liquid preparation circulation tank, and an absorption circulation pump;

[0018] Wherein, the titanium tetrachloride flowmeter is connected to the first suction port of the venturi mixer; the circulating liquid inlet of the venturi mixer is connected to the outlet pipe of the liquid distribution circulation pump, and the mixed liquid outlet of the venturi mixer is connected to the upper tube side inlet of the heat exchanger; the pure water flowmeter is connected to the second suction port of the venturi mixer; the upper liquid inlet of the falling film absorber is connected to the outlet of the absorption circulation pump through a pipeline, the lower tube side outlet of the falling film absorber is connected to the inlet of the liquid distribution circulation tank, and the upper tube side outlet of the falling film absorber is connected to the lower air inlet pipe of the hydrochloric acid absorber; the lower gas inlet of the hydrochloric acid absorber is connected to the gas outlet of the falling film absorber through a pipeline; the upper gas outlet of the heat exchanger is connected to the lower tube side inlet of the falling film absorber, and the lower tube side outlet of the heat exchanger is connected to the inlet of the liquid distribution circulation tank; the inlet pipe of the liquid distribution circulation pump is connected to the outlet of the liquid distribution circulation tank; the inlet pipe of the absorption circulation pump is connected to the outlet of the liquid distribution circulation tank. The use of a Venturi mixer to simultaneously and continuously extract titanium tetrachloride and pure water can achieve continuous production; the use of a Venturi mixer to mix a large amount of circulating mother liquor with a small amount of titanium tetrachloride and a small amount of pure water reduces the reaction temperature rise and the concentration gradient.

[0019] The titanium tetrachloride flowmeter is preferably a mass flowmeter, and the pure water flowmeter is preferably a vortex flowmeter.

[0020] The flow rates of titanium tetrachloride and pure water extracted by the venturi mixer are set according to the concentration of the titanium dichloride solution to be prepared. The flow rate of the suction pipe is adjusted by the valve opening and monitored by a flow meter.

[0021] The falling film absorber absorbs the hydrogen chloride generated by the reaction and returns it to the circulating mother liquid in the form of hydrochloric acid. Hydrochloric acid can maintain the acidity of the prepared titanium dichloride solution and inhibit the further occurrence of excessive hydrolysis side reactions. The heat absorbed by the hydrochloric acid in the falling film absorber is taken away by the refrigerant, and the heat exchange function of the falling film absorber can also reduce the temperature of the circulating liquid.

[0022] The liquid circulation pump is used to pump the circulating mother liquid into the Venturi mixer and provide power for the two suction port pipes of the Venturi mixer to generate vacuum.

[0023] The liquid circulation tank is used to buffer and store the prepared titanium oxychloride solution and provide a volume space for solution circulation and mixing.

[0024] The absorption circulation pump is used to pump the circulating mother liquor to the falling film absorber; it is also used to transport the prepared titanium oxychloride solution to the required process.

[0025] Preferably, in the above device, the Venturi mixer includes a circulating liquid inlet, a nozzle, a contraction section, a diffusion section, a mixing chamber, a first suction port, a second suction port and a mixed liquid outlet; the first suction port enters the mixing chamber from the tangent direction of the outer circle of the mixing chamber; the second suction port enters the mixing chamber from the tangent direction of the outer circle of the mixing chamber; the center lines of the first suction port and the second suction port are parallel to each other in space, and the first suction port and the second suction port are located at any axial position of the outer circle surface of the mixing chamber. Preferably, the first suction port and the second suction port are located in the same cross-section of the mixing chamber; the center line of the first suction port and the center line of the circulating liquid inlet are perpendicular and do not intersect in space; the center line of the second suction port and the center line of the circulating liquid inlet are perpendicular and do not intersect in space.

[0026] When the circulating mother liquid is ejected through the nozzle (smaller than the circulating liquid inlet diameter), the flow rate increases and the pressure decreases, thereby forming a certain vacuum in the mixing chamber. Titanium tetrachloride and pure water enter the Venturi mixer from two suction pipes respectively with the help of vacuum. The two suction pipes arranged tangentially can reduce the mutual influence when the pressure of the two suction pipes is unbalanced, and are more conducive to uniform mixing.

[0027] Preferably, in the above device, a gas-liquid separation space is provided on the upper part of the tube side of the heat exchanger. The gas-liquid separation space can prevent gas from entering the tube side of the heat exchanger and affecting heat exchange.

[0028] Preferably, in the above device, the device further comprises a U-shaped tube; the U-shaped tube is arranged between the outlet of the lower tube side of the heat exchanger and the inlet of the liquid distribution circulation tank; preferably, a drain pipe and a valve are arranged at the bottom of the U-shaped tube. The drain pipe and valve are arranged at the bottom of the U-shaped tube to facilitate draining during maintenance.

[0029] Preferably, in the above device, the refrigerant is in the shell side of the heat exchanger, and the reaction heat is taken away by the refrigerant. The temperature of the titanium oxychloride solution can be adjusted by adjusting the flow rate and temperature of the refrigerant.

[0030] Preferably, in the above device, the height of the U-shaped tube is 50% to 90%, preferably 80%, of the tube height of the heat exchanger. The U-shaped tube within the above height range can ensure that the liquid in the tube of the heat exchanger fills the pipe.

[0031] Preferably, in the above-mentioned device, the device also includes: an exhaust gas fan, a hydrochloric acid circulation tank, and a hydrochloric acid circulation pump; wherein the upper gas outlet of the hydrochloric acid absorption tower is connected to the inlet of the exhaust gas fan through a pipeline, the upper liquid inlet of the hydrochloric acid absorption tower is connected to the outlet pipe of the hydrochloric acid circulation pump through a pipeline, and the lower liquid outlet of the hydrochloric acid absorption tower is connected to the inlet of the hydrochloric acid circulation tank through a pipeline; the outlet of the exhaust gas fan is connected to the exhaust gas treatment system; the outlet of the hydrochloric acid circulation tank is connected to the inlet of the hydrochloric acid circulation pump; and a pure water addition inlet is provided on the hydrochloric acid circulation tank.

[0032] The hydrochloric acid absorption tower is used to absorb the hydrogen chloride gas that is not completely absorbed by the falling film absorber, produce by-product hydrochloric acid, and improve economic benefits.

[0033] A small amount of tail gas enters the tail gas treatment system through the tail gas fan and is discharged after being treated as qualified. The tail gas fan is set at the very end of the gas phase pipeline of the entire device, so that the entire device can maintain a slight negative pressure and reduce the risk of environmental pollution caused by hydrogen chloride gas leakage at each sealing point in the device.

[0034] The hydrochloric acid circulation tank is used to buffer and store byproduct hydrochloric acid and provide a volume space for the circulation and mixing of hydrochloric acid. The hydrochloric acid circulation tank is provided with a pure water inlet, and the addition of pure water can adjust the hydrochloric acid concentration and maintain the ability of the hydrochloric acid circulating fluid to absorb hydrogen chloride.

[0035] The hydrochloric acid circulation pump is used to pump the hydrochloric acid circulating liquid; it is also used to transport the by-product hydrochloric acid to the required process.

[0036] In a second aspect, the present invention provides a process for continuously preparing titanium dichloride solution, comprising the following steps: titanium tetrachloride is extracted from a first suction port into a venturi mixer through a titanium tetrachloride flowmeter, pure water is extracted from a second suction port into the venturi mixer through a pure water flowmeter, and circulating mother liquor is transported into the venturi mixer by a liquid preparation circulation pump, the extracted titanium tetrachloride and pure water are fully mixed with a large amount of circulating mother liquor, the produced titanium dichloride solution is transported into a liquid preparation circulation tank, the heat generated by the mixing reaction is taken away by the refrigerant in the heat exchanger, the hydrogen chloride gas generated by the reaction is first transported into a falling film absorber by an absorption circulation pump for absorption, and then returned to the circulating mother liquor in the liquid preparation circulation tank in the form of hydrochloric acid, and the remaining hydrogen chloride gas is washed and absorbed by a hydrochloric acid absorption tower to obtain a by-product hydrochloric acid.

[0037] The hydrogen chloride absorbed by the falling film absorber is returned to the circulating mother liquor in the form of hydrochloric acid, which can inhibit the excessive hydrolysis of the titanium dichloride solution.

[0038] Preferably, in the above process, titanium tetrachloride is drawn from the outer tangent direction of the mixing chamber through the first suction port through the titanium tetrachloride flowmeter to the venturi mixer, and pure water is drawn from the outer tangent direction of the mixing chamber through the second suction port through the pure water flowmeter to the venturi mixer, and the flow direction of the titanium tetrachloride and the flow direction of the circulating mother liquor form a spiral mixture, and the flow direction of the pure water and the flow direction of the circulating mother liquor form a spiral mixture. The tangential direction of entry is to reduce the mutual interference when the pressure of the two suction port pipes is unbalanced, and the spiral mixing is more uniform.

[0039] The flow rate of the circulating liquid inlet pipe of the venturi mixer is several to dozens of times the flow rate of the extracted titanium tetrachloride and pure water. A large amount of circulating mother liquid can reduce the concentration gradient change of the prepared titanium dichloride solution. At the same time, a large amount of circulating mother liquid can be used as a heat carrier to reduce the temperature rise of the reaction system, thereby bringing heat into the heat exchanger.

[0040] Preferably, in the above process, the hydrogen chloride gas generated by the reaction is separated from the liquid through the gas-liquid separation space at the upper part of the heat exchanger tube side, and after separation, the hydrogen chloride gas enters the falling film absorber through the gas phase pipeline, and the liquid enters the tube side of the heat exchanger.

[0041] Preferably, in the above process, the refrigerant is one or more of circulating cooling water, chilled brine, and ethylene glycol mixed water solution.

[0042] When the concentration of the prepared titanium dichloride solution is greater than or equal to 4 mol / L, the refrigerant is preferably circulating cooling water; when the concentration of the prepared titanium dichloride solution is lower than 4 mol / L, the refrigerant is preferably a low-temperature ethylene glycol mixed aqueous solution at -10°C to -30°C.

[0043] Preferably, when the concentration of the prepared titanium oxychloride solution is greater than or equal to 4 mol / L, the temperature of the prepared titanium oxychloride solution is controlled to be lower than 50°C; preferably, when the concentration of the prepared titanium oxychloride solution is equal to 2 mol / L, the temperature of the prepared titanium oxychloride solution is controlled to be lower than 18°C.

[0044] Preferably, in the above process, the by-product hydrochloric acid is transported into the hydrochloric acid circulation tank by the hydrochloric acid circulation pump, and a small amount of tail gas enters the tail gas treatment system through the tail gas fan for treatment.

[0045] The technical solution of the present invention has the following advantages:

[0046] The device and process for preparing titanium dichloride solution of the present invention can continuously produce titanium dichloride solution with adjustable concentration and temperature, and can remove the reaction heat generated by continuous mixing reaction, avoid boiling caused by large amount of heat release, and inhibit the occurrence of excessive hydrolysis side reaction. Since the whole system operates under slight negative pressure, there is no potential safety hazard of gas leakage. The device and process of the present invention can continuously suck and transport titanium tetrachloride under negative pressure according to metering, which is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0048] Figure 1 It is a schematic diagram of the structure of the device for continuously preparing titanium oxychloride solution in Example 1 of the present invention; wherein, 1—titanium tetrachloride flowmeter, 2—Venturi mixer, 3—pure water flowmeter, 4—falling film absorber, 5—hydrochloric acid absorption tower, 6—exhaust fan, 7—heat exchanger, 8—U-shaped tube, 9—liquid preparation circulation pump, 10—liquid preparation circulation tank, 11—absorption circulation pump, 12—hydrochloric acid circulation tank, 13—hydrochloric acid circulation pump;

[0049] Figure 2 It is a schematic diagram of the structure of the Venturi mixer in Example 1 of the present invention; wherein, 14 is a circulating liquid inlet, 15 is a mixing chamber, 16 is a nozzle, 17 is a contraction section, 18 is a diffusion section, 19 is a mixed liquid outlet, 20 is a first suction port, and 21 is a second suction port. DETAILED DESCRIPTION Example 1

[0050] like Figure 1 As shown, the device for continuously preparing titanium oxychloride solution in this embodiment includes: a titanium tetrachloride flowmeter 1, a Venturi mixer 2, a pure water flowmeter 3, a falling film absorber 4, a hydrochloric acid absorption tower 5, an exhaust fan 6, a heat exchanger 7, a U-shaped tube 8, a liquid preparation circulation pump 9, a liquid preparation circulation tank 10, an absorption circulation pump 11, a hydrochloric acid circulation tank 12, and a hydrochloric acid circulation pump 13.

[0051] Wherein, the titanium tetrachloride flowmeter 1 is connected to the first suction port 20 of the venturi mixer 2; the circulating liquid inlet 14 of the venturi mixer 2 is connected to the outlet pipe of the liquid distribution circulation pump 9, and the mixed liquid outlet 19 of the venturi mixer 2 is connected to the upper pipe side inlet of the heat exchanger 7; the pure water flowmeter 3 is connected to the second suction port 21 of the venturi mixer 2; the upper liquid inlet of the falling film absorber 4 is connected to the outlet of the absorption circulation pump 11 through a pipeline, the lower pipe side outlet of the falling film absorber 4 is connected to the inlet of the liquid distribution circulation tank 10, and the upper pipe side outlet of the falling film absorber 4 is connected to the lower air inlet pipe of the hydrochloric acid absorption tower 5; the lower gas inlet of the hydrochloric acid absorption tower 5 is connected to the gas outlet of the falling film absorber 4 through a pipeline, the upper gas outlet of the hydrochloric acid absorption tower 5 is connected to the inlet of the exhaust fan 6 through a pipeline, the upper liquid inlet of the hydrochloric acid absorption tower 5 is connected to the outlet pipe of the hydrochloric acid circulation pump 13 through a pipeline, and the lower gas outlet of the hydrochloric acid absorption tower 5 is connected to the lower gas outlet of the hydrochloric acid absorption tower 5. The liquid outlet is connected to the inlet of the hydrochloric acid circulation tank 12 through a pipeline; the outlet of the exhaust fan 6 is connected to the exhaust gas treatment system; the upper gas outlet of the heat exchanger 7 is connected to the lower tube side inlet of the falling film absorber 4, the lower tube side outlet of the heat exchanger 7 is connected to the inlet of the liquid circulation tank 10, and a gas-liquid separation space is provided on the upper part of the tube side of the heat exchanger 7; the heat exchanger 7 is a YKch-30 round block hole type graphite dilution cooler with a heat exchange area of ​​30 square meters; the U-shaped tube 8 is arranged between the outlet of the lower tube side of the heat exchanger 7 and the inlet of the liquid preparation circulation tank 10, the height of the U-shaped tube 8 is 80% of the height of the tube side of the heat exchanger 7, and the diameter of the U-shaped tube 8 is 200mm; the inlet pipe of the liquid preparation circulation pump 9 is connected to the outlet of the liquid preparation circulation tank 10; the inlet pipe of the absorption circulation pump 11 is connected to the outlet of the liquid preparation circulation tank 10; the outlet of the hydrochloric acid circulation tank 12 is connected to the inlet of the hydrochloric acid circulation pump 13, and the hydrochloric acid circulation tank 12 is provided with a pure water addition inlet.

[0052] like Figure 2As shown, in this embodiment, the venturi mixer 2 includes a circulating liquid inlet 14, a mixing chamber 15, a nozzle 16, a contraction section 17, a diffusion section 18, a mixed liquid outlet 19, a first suction port 20 and a second suction port 21. The first suction port 20 enters the mixing chamber 15 from the tangent direction of the outer circle of the mixing chamber 15; the second suction port 21 enters the mixing chamber 15 from the tangent direction of the outer circle of the mixing chamber 15; the center lines of the first suction port 20 and the second suction port 21 are parallel to each other in space, the first suction port 20 and the second suction port 21 are located at any position of the axial direction of the outer circle surface of the mixing chamber, and the first suction port 20 and the second suction port 21 are located in the same cross section of the mixing chamber 15; the center line of the first suction port 20 and the center line of the circulating liquid inlet 14 are vertical and do not intersect in space; the center line of the second suction port 21 and the center line of the circulating liquid inlet 14 are vertical and do not intersect in space. The relationship between the structural parameters is as follows: the relationship between the diameter d1 of the circulating liquid inlet 14 and the diameter d2 of the nozzle 16 is d1≈2×d2; the relationship between the diameter d2 of the nozzle 16 and the diameter d3 of the contraction section 17 is d2≈d3; the relationship between the length h of the contraction section 17 and the diameter d3 of the contraction section 17 is h≈d3; the distance h1 between the end of the nozzle 16 and the contraction section 17 is d2≈d2; the relationship between the diameter d5 of the first suction port 20 and the diameter d2 of the nozzle 16 is d5=(0.2~0.3)×d2; the relationship between the diameter d4 of the mixed liquid outlet 19 and the diameter d1 of the circulating liquid inlet 14 is d4≈1.5×d1; the angle of the diffusion section 18 is about 7°; the angle of the contraction section is about 25°. The specific structural parameters are: d1=65mm, d2=30mm, d3=30mm, d4=100mm, d5=15mm, d5=15mm, h=30mm, h1=30mm, the angle of the diffuser 18 is 7°, and the angle of the contraction section is 25°. The material of the Venturi mixer 2 is titanium alloy TA2 or polytetrafluoroethylene.

[0053] The start-up sequence of the device for continuously preparing titanium oxychloride solution in this embodiment is as follows:

[0054] 1) Close the valve of the first suction port 20;

[0055] 2) closing the valve of the second suction port 21;

[0056] 3) close the valve of the hydrochloric acid outlet pipe on the outlet branch of the hydrochloric acid circulation pump 13;

[0057] 4) closing the valve of the titanium dichloride outlet pipe on the outlet branch of the absorption circulation pump 11;

[0058] 5) Open the valve of the refrigerant inlet of the falling film absorber 4, and the refrigerant enters the shell side of the falling film absorber;

[0059] 6) Open the valve of the refrigerant outlet of the falling film absorber 4, and the refrigerant takes away the reaction heat from the shell side;

[0060] 7) Open the refrigerant inlet valve of heat exchanger 7, and the refrigerant enters the shell side of the heat exchanger;

[0061] 8) Open the refrigerant outlet valve of heat exchanger 7, and the refrigerant takes away the reaction heat from the shell side;

[0062] 9) Adding a titanium oxychloride solution of the concentration to be prepared into the liquid circulation tank 10 as a circulating mother liquid, the circulating mother liquid can reduce the concentration gradient of the preparation process, and can also serve as a heat carrier to reduce the temperature rise of the preparation process and bring heat into the heat exchanger;

[0063] 10) Adding pure water into the hydrochloric acid circulation tank 12, the pure water acts as an absorbent to absorb the hydrogen chloride gas;

[0064] 11) The tail gas treatment system should be prepared for tail gas treatment;

[0065] 12) Start the exhaust fan 6 to provide a slight negative pressure for the entire system and provide power for gas phase flow;

[0066] 13) starting the hydrochloric acid circulation pump 13 to pump the hydrochloric acid circulation liquid;

[0067] 14) Start the absorption circulation pump 11 to pump the circulating absorption liquid;

[0068] 15) Start the liquid preparation circulation pump 9 to pump the prepared circulating liquid, and the circulating liquid provides power for generating negative pressure at the suction port of the Venturi mixer;

[0069] 16) Open the valve of the pure water inlet of the second suction port 21, observe the pure water flow meter 3, and adjust the valve opening to the set flow rate;

[0070] 17) Open the valve of the titanium tetrachloride inlet of the first suction port 20, observe the titanium tetrachloride flowmeter 1, and adjust the valve opening to the set flow rate;

[0071] 18) Depending on the temperature of the prepared titanium oxychloride solution, adjust the opening of the refrigerant inlet valve of the heat exchanger 7, or adjust the temperature of the refrigerant and adjust the opening of the refrigerant inlet valve of the falling film absorber 4;

[0072] 19) Sampling and testing the concentration of the titanium oxychloride solution, and fine-tuning the flow rate of titanium tetrachloride or pure water into the venturi mixer 2 according to the concentration change;

[0073] 20) Sampling and testing the concentration of by-product hydrochloric acid, and adjusting the flow rate of pure water into the hydrochloric acid circulation tank 12 according to the concentration change;

[0074] 21) After the system is stable, the valve on the outlet branch of the absorption circulation pump 11 can be opened to continuously produce qualified titanium dichloride solution according to the required amount;

[0075] 22) After the system is stable, the valve on the outlet branch of the hydrochloric acid circulation pump 13 can be opened to continuously produce by-product hydrochloric acid according to the required amount;

[0076] 23) Driving completed.

[0077] The parking order is as follows:

[0078] 1) Close the valve of the hydrochloric acid outlet pipe on the outlet branch of the hydrochloric acid circulation pump 13;

[0079] 2) closing the valve of the titanium dichloride outlet pipe on the outlet branch of the absorption circulation pump 11;

[0080] 3) closing the valve of the first suction port 20 to stop the supply of titanium tetrachloride;

[0081] 4) Close the valve of the second suction port 21 to stop the pure water supply;

[0082] 5) Close the pure water inlet valve on the hydrochloric acid circulation tank 12;

[0083] 6) After the cycle runs for a period of time;

[0084] 7) Close the valve of the refrigerant inlet of the falling film absorber 4;

[0085] 8) Close the valve of the refrigerant outlet of the falling film absorber 4;

[0086] 9) Close the refrigerant inlet valve of heat exchanger 7;

[0087] 10) Close the refrigerant outlet valve of heat exchanger 7;

[0088] 11) Stop the liquid distribution circulation pump 9;

[0089] 12) Stop the absorption circulation pump 11;

[0090] 13) Stop the hydrochloric acid circulation pump 13;

[0091] 14) Stop the exhaust fan 6;

[0092] 15) Parking is completed.

[0093] The process of continuously preparing a titanium dichloride solution with a concentration of 4 mol / L in this embodiment comprises the following steps: titanium tetrachloride is drawn from the outer tangential direction of the mixing chamber 15 to the venturi mixer 2 through the titanium tetrachloride flowmeter 1 from the first suction port 20, and pure water is drawn from the outer tangential direction of the mixing chamber 15 to the venturi mixer 2 through the pure water flowmeter 3 from the second suction port 21, the flow direction of the titanium tetrachloride and the flow direction of the circulating mother liquid form a spiral mixing, and the flow direction of the pure water and the flow direction of the circulating mother liquid form a spiral mixing, and the circulating mother liquid is mixed with the titanium tetrachloride. The circulating pump 9 delivers the gas into the venturi mixer 2, where the extracted titanium tetrachloride and pure water are fully mixed with a large amount of circulating mother liquor. The heat generated by the mixing reaction is taken away by the refrigerant circulating cooling water in the heat exchanger 7, where the inlet temperature of the refrigerant circulating cooling water is 32°C and the outlet temperature is 37°C. The hydrogen chloride gas generated by the reaction is first delivered by the absorption circulating pump 11 into the falling film absorber 4 for absorption, and then returned to the circulating mother liquor in the liquid preparation circulation tank 10 in the form of hydrochloric acid. The remaining hydrogen chloride gas is washed and absorbed by the hydrochloric acid absorption tower 5 to obtain by-product hydrochloric acid.

[0094] The hydrogen chloride gas generated by the reaction is separated from the liquid through the gas-liquid separation space at the upper part of the tube side of the heat exchanger 7. After separation, the hydrogen chloride gas enters the falling film absorber 4 through the gas phase pipeline, and the liquid enters the tube side of the heat exchanger 7. The byproduct hydrochloric acid is transported into the hydrochloric acid circulation tank 12 by the hydrochloric acid circulation pump 13, and a small amount of tail gas enters the tail gas treatment system through the tail gas fan 6 for treatment.

[0095] The flow rate of titanium tetrachloride introduced into the first suction port 20 of the venturi mixer 2 is 750 L / h, and the flow rate of pure water introduced into the second suction port 21 is 1000 L / h. The flow rate Q of the liquid circulation pump 9 is 50 m 3 / h, head H = 30m; flow rate Q = 50m 3 / h, head H = 30m; flow rate Q = 50m of hydrochloric acid circulation pump 13 3 / h, lift H=30m.

[0096] The device and process for continuously preparing titanium oxychloride solution in this embodiment can realize the production of titanium oxychloride solution with a concentration of 4 mol / L and a temperature of ≤50° C. at a continuous production capacity of 1250 L / h. Comparative Example 1

[0097] The operation is carried out using a titanium tetrachloride dilution complete set as disclosed in CN2923668Y, which consists of a titanium tetrachloride metering tank, a glass sight glass, a mixing nozzle, a vacuum unit, a titanium tetrachloride preparation tank, a primary falling film absorption tower, an absorption circulation tank, a secondary falling film absorption tower, a voltage regulator tube, and a No. 2 circulation pump.

[0098] Since the device uses a vacuum unit to pump titanium tetrachloride into the metering tank, this method of transferring titanium tetrachloride will cause hydrochloric acid mist to enter the vacuum unit, which can easily cause corrosion damage to the vacuum unit.

[0099] The device adopts intermittent operation mode, and intermittent operation cannot avoid that the ratio of water to titanium tetrachloride is much greater than the chemical equilibrium of titanium dichloride in the initial preparation, causing the side reaction of excessive hydrolysis. Comparative Example 2

[0100] The titanium tetrachloride aqueous solution preparation device disclosed in CN102764601 is used for operation, which is composed of a jet vacuum pump, an anti-corrosion centrifugal pump, a graphite heat exchanger, a titanium tetrachloride mixing tank, an absorption tower, a centrifugal fan, etc.

[0101] The device uses a jet vacuum pump to suck titanium tetrachloride and mix it with the circulating liquid, which has the problem of unbalanced suction. In addition, the device adopts intermittent operation. When pure water is added, the concentration of the system solution will decrease, and when titanium tetrachloride is added, the concentration of the system solution will increase. The entire process operation is a process of fluctuation in the concentration of the system solution.

[0102] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A device for continuously preparing titanium oxychloride solution, characterized in that: include: Titanium tetrachloride flowmeter (1), Venturi mixer (2), pure water flowmeter (3), falling film absorber (4), hydrochloric acid absorption tower (5), heat exchanger (7), liquid distribution circulation pump (9), liquid distribution circulation tank (10), absorption circulation pump (11); The titanium tetrachloride flowmeter (1) is connected to the first suction port (20) of the venturi mixer (2); the circulating liquid inlet (14) of the venturi mixer (2) is connected to the outlet pipe of the liquid distribution circulation pump (9); the mixed liquid outlet (19) of the venturi mixer (2) is connected to the upper pipe side inlet of the heat exchanger (7); the pure water flowmeter (3) is connected to the second suction port (21) of the venturi mixer (2); the upper liquid inlet of the falling film absorber (4) is connected to the outlet of the absorption circulation pump (11) through a pipeline, and the lower pipe side outlet of the falling film absorber (4) is connected to the liquid distribution circulation tank. The inlet of the falling film absorber (10) is connected, the upper tube side outlet of the falling film absorber (4) is connected to the lower air inlet pipe of the hydrochloric acid absorption tower (5); the lower gas inlet of the hydrochloric acid absorption tower (5) is connected to the gas outlet of the falling film absorber (4) through a pipeline; the upper gas outlet of the heat exchanger (7) is connected to the lower tube side inlet of the falling film absorber (4), and the lower tube side outlet of the heat exchanger (7) is connected to the inlet of the liquid distribution circulation tank (10); the inlet pipe of the liquid distribution circulation pump (9) is connected to the outlet of the liquid distribution circulation tank (10); the inlet pipe of the absorption circulation pump (11) is connected to the outlet of the liquid distribution circulation tank (10); The venturi mixer (2) comprises a circulating liquid inlet (14), a contraction section (17), a nozzle (16), a diffusion section (18), a mixing chamber (15), a first suction port (20), a second suction port (21) and a mixed liquid outlet (19); the first suction port (20) enters the mixing chamber (15) from the direction of the outer tangent of the mixing chamber (15); the second suction port (21) enters the mixing chamber (15) from the direction of the outer tangent of the mixing chamber (15); the center lines of the first suction port (20) and the second suction port (21) are parallel to each other in space, and the first suction port (20) and the second suction port (21) are located at any axial position on the outer circumferential surface of the mixing chamber. The device further comprises: an exhaust gas fan (6), a hydrochloric acid circulation tank (12), and a hydrochloric acid circulation pump (13); wherein the upper gas outlet of the hydrochloric acid absorption tower (5) is connected to the inlet of the exhaust gas fan (6) via a pipeline, the upper liquid inlet of the hydrochloric acid absorption tower (5) is connected to the outlet pipe of the hydrochloric acid circulation pump (13) via a pipeline, the lower liquid outlet of the hydrochloric acid absorption tower (5) is connected to the inlet of the hydrochloric acid circulation tank (12) via a pipeline, the outlet of the exhaust gas fan (6) is connected to the exhaust gas treatment system, the outlet of the hydrochloric acid circulation tank (12) is connected to the inlet of the hydrochloric acid circulation pump (13), and the hydrochloric acid circulation tank (12) is provided with a pure water inlet. The device further comprises a U-shaped tube (8), wherein the U-shaped tube (8) is arranged between the outlet of the lower tube side of the heat exchanger (7) and the inlet of the liquid distribution circulation tank (10).

2. The device according to claim 1, characterized in that The first suction port (20) and the second suction port (21) are located in the same cross section of the mixing chamber (15); the center line of the first suction port (20) and the center line of the circulating liquid inlet (14) do not intersect each other vertically in space; and the center line of the second suction port (21) and the center line of the circulating liquid inlet (14) do not intersect each other vertically in space.

3. The device according to claim 1, characterized in that A gas-liquid separation space is provided at the upper part of the tube side of the heat exchanger (7).

4. The device according to any one of claims 1 to 3, characterized in that A drain pipe and a valve are provided at the bottom of the U-shaped tube (8).

5. The device according to claim 4, characterized in that The height of the U-shaped tube (8) is 50% to 90% of the tube height of the heat exchanger (7).

6. The device according to claim 5, characterized in that The height of the U-shaped tube (8) is 80% of the tube height of the heat exchanger (7).

7. A process for continuously preparing titanium oxychloride solution, characterized in that: The device for continuously preparing titanium dichloride solution according to any one of claims 1 to 6 comprises the following steps: titanium tetrachloride is extracted from a first suction port (20) into a venturi mixer (2) through a titanium tetrachloride flowmeter (1), and pure water is extracted from a second suction port (21) into the venturi mixer (2) through a pure water flowmeter (3), and a circulating mother liquor is transported into the venturi mixer (2) by a liquid preparation circulation pump (9), the extracted titanium tetrachloride and pure water are fully mixed with a large amount of circulating mother liquor, and the produced titanium dichloride solution is transported into a liquid preparation circulation tank (10), and the heat generated by the mixing reaction is taken away by the refrigerant in the heat exchanger (7), and the hydrogen chloride gas generated by the reaction is first transported into a falling film absorber (4) by an absorption circulation pump (11) for absorption, and then returned to the circulating mother liquor in the liquid preparation circulation tank (10) in the form of hydrochloric acid, and the remaining hydrogen chloride gas is washed and absorbed by a hydrochloric acid absorption tower (5) to obtain a by-product hydrochloric acid.

8. The process according to claim 7, characterized in that Titanium tetrachloride is drawn from the outer tangent direction of the mixing chamber (15) into the Venturi mixer (2) through the titanium tetrachloride flowmeter (1) from the first suction port (20), and pure water is drawn from the outer tangent direction of the mixing chamber (15) into the Venturi mixer (2) through the pure water flowmeter (3) from the second suction port (21), the flow direction of the titanium tetrachloride and the flow direction of the circulating mother liquor form a spiral mixing, and the flow direction of the pure water and the flow direction of the circulating mother liquor form a spiral mixing.

9. The process according to claim 7 or 8, characterized in that The hydrogen chloride gas generated by the reaction is separated from the liquid through the gas-liquid separation space at the top of the tube side of the heat exchanger (7). After the separation, the hydrogen chloride gas enters the falling film absorber (4) through the gas phase pipeline, and the liquid enters the tube side of the heat exchanger (7).

10. The process according to claim 7, characterized in that The refrigerant is one or more of circulating cooling water, chilled brine, and ethylene glycol mixed water solution; and / or The by-product hydrochloric acid is transported by the hydrochloric acid circulation pump (13) into the hydrochloric acid circulation tank (12), and a small amount of tail gas is sent to the tail gas treatment system through the tail gas fan (6) for treatment.

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