A system and method for chlorinated flue gas cooling and dust collection

Abstract

A system and method for cooling and dust collecting of chlorination flue gas, the system comprising a pre-quenching device, a quenching granulator, a cyclone separator, a granulated material bin, a spray washing dust removal tower, a heat exchanger, a slurry tank, a circulating pump and a slurry delivery pump. The method is: sending high-temperature chlorination flue gas into the pre-quenching device, spraying titanium tetrachloride liquid to cool down, then sending into the quenching granulator and the cyclone separator to realize cooling and dust removal, and then into the spray washing dust removal tower to realize condensation and deep dust removal, and sending the spray washing slurry to the centrifugal granulation separation to realize the removal of titanium tetrachloride solid content. The advantages are: through the pre-quenching of titanium tetrachloride liquid, the problem of quenching device blockage caused by one-step quenching is avoided, and the temperature is effectively reduced to create conditions for subsequent quenching and granulation; through centrifugal granulation, dust in flue gas and spray washing liquid is effectively gathered to realize efficient cooling and dust removal; by spraying alkali into the spray washing dust removal tower to selectively hydrolyze aluminum chloride in the flue gas, the problem of cooling and spray washing caused by aluminum chloride saturation precipitation and scaling blockage is effectively avoided.

Description

Technical Field

[0001] This invention relates to the fields of chemical engineering and metallurgy, and in particular to a system and method for cooling and collecting dust from chlorinated flue gas. Background Technology

[0002] Titanium tetrachloride is an intermediate product in the production of titanium and its compounds, and an important raw material for the development of the titanium industry. It can be used to produce high-end titanium dioxide, sponge titanium, and further titanium and titanium alloys. With the rapid development of the titanium industry in recent years, the demand for titanium raw materials has been increasing. Currently, there are two main utilization pathways for titanium resources: the chlorination process and the sulfuric acid process. The chlorination process includes fluidized bed chlorination and molten salt chlorination. Fluidized bed chlorination refers to the carbon-containing chlorination of titanium-containing materials in a fluidized bed to obtain titanium tetrachloride as an intermediate product. Titanium tetrachloride can be oxidized to produce titanium dioxide or reduced with magnesium to produce sponge titanium. Fluidized bed chlorination is a mainstream advanced titanium resource utilization technology due to its short process flow, low cost, low pollution, and high capacity. However, during the fluidized bed chlorination process, fine powder is generated due to collisions between particles and between particles and the vessel wall. Furthermore, the chlorination reaction itself also leads to particle refinement and the generation of fine powder, resulting in a large amount of fine powder in the flue gas exiting the fluidized bed chlorination furnace. In addition, the chlorinated flue gas also contains high-boiling-point chlorides such as ferric chloride and aluminum trichloride. To prevent dust and high-boiling-point chlorides from condensing and entering subsequent titanium tetrachloride products, titanium dioxide manufacturers have implemented dust collection measures.

[0003] Currently, the main method for treating high-temperature titanium tetrachloride dust-laden gas, both domestically and internationally, involves using crude titanium tetrachloride from the condensation and collection process and vanadium slag slurry from the refining process as spray slurry to rapidly cool the gas to approximately 200-300°C before it enters the dust collection chamber for gas-solid separation. However, severe scaling occurs in the rapid cooling area and the inlet pipe of the cyclone separator, requiring frequent shutdowns for cleaning. To address these issues, the technology developers have optimized the dust removal process.

[0004] CN108793237B discloses a "System and Method for Treating High-Temperature Titanium Tetrachloride Dust-laden Gas". This method eliminates the existing quenching and gas-solid separation processes, and sets up a wet chlorination slag baking process, a condensation and pulping process, and a solid-liquid separation process. Specifically, high-temperature chlorination flue gas is sent into a rotary kiln, and wet solids obtained by centrifugation are sent into the rotary kiln. The high-temperature chlorination flue gas and wet solids are cooled to 400-600°C through countercurrent contact. The titanium tetrachloride in the wet chlorination slag is evaporated and enters the dust-laden gas. The temperature of the wet chlorination slag rises and it is sent to a cooling kiln for further cooling before being sent for treatment. Although this method eliminates the quenching and gas-solid separation processes, the wet chlorination slag obtained by centrifugation has poor fluidity and agglomeration occurs in the rotary kiln. In addition, this method mainly cools the high-temperature chlorination flue gas through the wet solids, rather than removing the dust in the high-temperature flue gas. The wet chlorination slag is dried under the action of high-temperature flue gas, and some fine powder will enter the next process with the cooled flue gas, which will adversely affect the subsequent titanium tetrachloride condensation and tail gas treatment. CN101423246B discloses "A liquid-phase dust collection method for titanium tetrachloride solid dust collector residue." This method returns 2-30% of the titanium tetrachloride slurry from the leaching process to the temperature control and dust removal process. The temperature of the chlorination flue gas is controlled, and the solid dust collector is used to remove dust particles from the returned titanium tetrachloride. However, this method still does not solve the problem of frequent blockage of the injected slurry in the pipeline or cyclone separator inlet. CN101462766B discloses "A cooling process for titanium tetrachloride furnace gas." This method sends high-temperature dust-laden chlorination flue gas into a cyclone dust collector. The collected dust is returned to the chlorination furnace for further chlorination. After exiting the cyclone dust collector, the high-temperature gas enters a cooler with a water-cooled jacket to cool down. The cooled chlorination flue gas then enters a spray condenser tower for further cooling to 171-180°C, causing gaseous impurities such as AlCl3 and FeCl3 to condense. A bag filter is then used to remove the chloride residue, and the relatively clean chlorination flue gas enters subsequent processes for condensation. CN218516289U discloses a "High-Efficiency Gas-Solid Separation and Coke Fine Powder Recovery System for Flue Gas from a Flue-Boiling Chlorination Furnace." The system operates by having the high-temperature flue gas from the chlorination furnace pass through an α-cyclone separator and a circulating cyclone separator to remove dust particles larger than 10μm and 3μm, respectively. The collected dust then enters a pulping tank, where acidic liquid is added. Therefore, existing flue gas dust removal technologies essentially involve first using cyclone separation to separate and recover some dust before proceeding to subsequent processes for further dust removal. However, this method faces two problems: first, the particles entrained in the chlorination flue gas severely scour the cyclone separator, resulting in a short equipment operating cycle and frequent lining replacements; second, the dust removal efficiency is low, and subsequent processes generate high-solids-content slurry, leading to a high return spray load and a vicious cycle. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a system and method for effectively collecting dust in flue gas and washing liquid, separating and recovering it, significantly reducing the amount of dust in flue gas, enabling efficient cooling and dust removal of chlorinated flue gas, and avoiding subsequent cooling and washing sections from being blocked by scale formation due to saturation precipitation of aluminum chloride.

[0006] The technical solution of this invention is as follows:

[0007] A chlorinated flue gas cooling and dust collection system is characterized by comprising a pre-cooler, a cooler granulator, a cyclone separator, a granulated material silo, a scrubbing dust removal tower, a heat exchanger, a slurry storage tank, a circulating pump, and a slurry transfer pump.

[0008] The inlet of the pre-quencher is connected to the high-temperature chlorination flue gas pipeline, the inlet of the pre-quencher is connected to the crude titanium tetrachloride clear liquid pipeline, and the outlet of the pre-quencher is connected to the inlet of the quench granulator. The inlet of the quench granulator is connected to the second outlet of the slurry storage tank via a pipeline. A slurry transfer pump is installed on the pipeline between the quench granulator and the slurry storage tank. The outlet of the quench granulator is connected to the inlet of the cyclone separator, and the outlet of the quench granulator is connected to the inlet of the granulation material silo. The outlet of the cyclone separator is connected to the inlet of the granulation material silo. The air outlet is connected to the air inlet of the scrubbing dust removal tower via a pipeline, and an alkali solution pipeline is connected between the cyclone separator and the scrubbing dust removal tower. The air outlet of the scrubbing dust removal tower is connected to the flue gas scrubbing process pipeline, the feed inlet of the scrubbing dust removal tower is connected to the discharge outlet of the heat exchanger, and the discharge outlet of the scrubbing dust removal tower is connected to the feed inlet of the slurry storage tank. The feed inlet of the scrubbing dust removal tower is connected to the first discharge outlet of the slurry storage tank via a pipeline. A circulating pump and a heat exchanger are installed on the pipeline between the feed inlet of the slurry storage tank and the first discharge outlet of the scrubbing dust removal tower, and the discharge outlet of the circulating pump is connected to the feed inlet of the heat exchanger.

[0009] A method for cooling and collecting dust from chlorinated flue gas using the above-mentioned system includes the following steps:

[0010] High-temperature chlorinated flue gas containing dust is fed into a pre-quench cooler, where crude titanium tetrachloride solution is injected. After quenching, the flue gas is then fed into a quench granulator, where it is centrifugally sprayed into a slurry storage tank containing leaching slurry delivered by a slurry pump. Under centrifugal force, the sprayed slurry is thoroughly mixed with the chlorinated flue gas, achieving both cooling and dust removal of the high-temperature chlorinated flue gas. The centrifugal nozzle speed is 1000–30000 rpm, and the ratio of sprayed leaching slurry to high-temperature chlorinated flue gas containing dust is 5–20 kg / m³. 3The solids in the slurry and the dust in the high-temperature flue gas are granulated into granules by a rapid cooling granulator and enter the granulation material silo. The cooled chlorinated flue gas is sent to a cyclone dust collector, and the dust collected by the cyclone dust collector is also sent to the granulation material silo. The chlorinated flue gas separated by the cyclone dust collector is sent to a scrubbing dust removal tower for condensation and deep dust removal. Alkali solution is sprayed into the air inlet of the scrubbing dust removal tower 5, and the circulating scrubbing slurry is sprayed into the slurry storage tank through the liquid inlet of the scrubbing dust removal tower. The flue gas after scrubbing dust removal is sent to the flue gas scrubbing process, and the scrubbing slurry is sent to the slurry storage tank.

[0011] Furthermore, the volume fraction of gaseous titanium tetrachloride in the chlorinated flue gas is 20%–40%; the dust content is 50–300 g / Nm³. 3 The temperature is 800~1100℃.

[0012] Furthermore, crude titanium tetrachloride is injected into the crude titanium tetrachloride liquid pipe at the top of the pre-cooler to reduce the temperature of the chlorinated flue gas to 400-700°C.

[0013] Furthermore, the quench granulator uses a rotary nozzle, with the top spraying of washing slurry to reduce the temperature of the chlorinated flue gas to 200-400°C.

[0014] Furthermore, the gas outlet temperature of the scrubbing dust removal tower is 80–125°C, and the liquid-to-gas ratio during the circulating scrubbing process is 10–30 kg / m³. 3 The empty tower gas velocity in the scrubbing dust removal tower is 1.5 to 3.0 m / s, the gas residence time is 2 to 6 s, and the amount of alkali added is 100 wt.% to 300 wt.% of the theoretical amount of aluminum chloride hydrolysis.

[0015] Furthermore, the particle size formed by granulation of dust by the quench granulator is 0.1-2mm.

[0016] Furthermore, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution.

[0017] Furthermore, the potassium hydroxide solution has a mass concentration of 10%; the sodium hydroxide solution has a mass concentration of 10%.

[0018] Compared with the prior art, the present invention has the following outstanding advantages:

[0019] (1) By using a pre-quench cooler and a quench granulator, the flue gas temperature is reduced and titanium tetrachloride in the slurry is recovered by spraying and washing the slurry, which helps to improve the yield of titanium tetrachloride. The pre-quenching of the titanium tetrachloride liquid avoids the blockage problem of the quench cooler caused by the first-step quenching, and at the same time effectively reduces the temperature to create conditions for subsequent quench granulation. By using centrifugal spraying to enhance the mixing of the washing slurry and chlorinated flue gas, it helps the solid to aggregate into granules. Through granulation, the dust in the flue gas and washing liquid is effectively collected, separated and recovered, significantly reducing the amount of dust in the flue gas, realizing efficient cooling and dust removal of chlorinated flue gas, and effectively solving the problem of frequent blockage of the quench tube.

[0020] (2) By spraying a small amount of alkaline solution into the scrubbing dust removal tower, selective hydrolysis of aluminum chloride in the chlorinated flue gas is achieved, avoiding scaling and blockage caused by saturated precipitation of aluminum chloride during cooling scrubbing. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0022] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0023] In the diagram: 1-Pre-cooler, 2-Cooler granulator, 3-Cyclone separator, 4-Pelletized material silo, 5-Scrubber dust removal tower, 6-Heat exchanger, 7-Slurry storage tank, 8-Circulating pump, and 9-Slurry transfer pump. Detailed Implementation

[0024] Any feature disclosed in this specification, unless specifically stated otherwise, may be replaced by other equivalent or similar features. Unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features. The descriptions are merely for the purpose of aiding understanding the invention and should not be construed as limiting the invention.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] like Figure 1 As shown, the chlorinated flue gas cooling and dust collection system includes: a pre-cooler 1, a quench granulator 2, a cyclone separator 3, a granulated material silo 4, a scrubbing dust removal tower 5, a heat exchanger 6, a slurry storage tank 7, a circulating pump 8, and a slurry transfer pump 9.

[0028] The inlet of the pre-quench cooler 1 is connected to the high-temperature chlorination flue gas pipeline, the inlet of the pre-quench cooler 1 is connected to the crude titanium tetrachloride clear liquid pipeline, and the outlet of the pre-quench cooler 1 is connected to the inlet of the quench granulator 2. The inlet of the quench granulator 2 is connected to the second outlet of the slurry storage tank 7 via a pipeline. A slurry conveying pump 9 is installed on the pipeline between the quench granulator 2 and the slurry storage tank 7. The outlet of the quench granulator 2 is connected to the inlet of the cyclone separator 3, and the outlet of the quench granulator 2 is connected to the inlet of the granulation material bin 4. The outlet of the cyclone separator 3 is connected to the inlet of the granulation material bin 4. The outlet of the cyclone separator 3 is connected to the inlet of the scrubbing dust removal tower 5 via a pipeline, and an alkaline solution pipeline is connected to the pipeline between the cyclone separator 3 and the scrubbing dust removal tower 5; the outlet of the scrubbing dust removal tower 5 is connected to the flue gas scrubbing process pipeline, and the outlet of the scrubbing dust removal tower 5 is connected to the inlet of the slurry storage tank 7; the inlet of the scrubbing dust removal tower 5 is connected to the first outlet of the slurry storage tank 7 via a pipeline, and a circulating pump 8 and a heat exchanger 6 are installed on the pipeline between the inlet of the slurry storage tank 7 and the first outlet of the scrubbing dust removal tower 5, and the outlet of the circulating pump 8 is connected to the inlet of the heat exchanger 6.

[0029] The method for cooling and collecting dust from chlorinated flue gas using the above system includes the following steps:

[0030] The volume fraction of gaseous titanium tetrachloride in the high-temperature chlorination flue gas is 40%; the dust content is 300 g / Nm³. 3 The chlorinated flue gas, at a temperature of 1100℃, is introduced into the pre-quencher 1. Crude titanium tetrachloride is sprayed into the crude titanium tetrachloride clear liquid pipe at the top of the pre-quencher 1, cooling the chlorinated flue gas to 400℃. The cooled chlorinated flue gas then enters the quencher granulator 2. The leaching slurry in the slurry storage tank 7 is transported by the slurry transfer pump 9 to the spray inlet of the quencher granulator 2 and sprayed through a centrifugal nozzle at the top of the quencher granulator. The centrifugal nozzle rotates at 30,000 rpm, and the ratio of the sprayed leaching slurry to the dust-laden high-temperature chlorinated flue gas is 20 kg / m³. 3 The temperature of the chlorinated flue gas is further cooled to 200℃. After cooling, the chlorinated flue gas is sent to a cyclone dust collector 3 for further dust collection to obtain dust material. The dust generated by the rapid cooling granulator 2 is granulated to obtain 0.1-2mm particles, which are sent together with the dust material from the cyclone dust collector 3 into the granulation material silo 4. The chlorinated flue gas after dust removal by the cyclone dust collector 3 is sent to a scrubbing dust removal tower 5. The empty tower gas velocity in the scrubbing dust removal tower 5 is 3m / s, and the gas residence time is 2s. A 10% sodium hydroxide solution is sprayed into the air inlet of the scrubbing dust removal tower 5, with the amount added being 150wt.% of the theoretical hydrolysis amount of aluminum chloride in the chlorinated flue gas, to neutralize the aluminum chloride in the flue gas. At the same time, circulating scrubbing slurry cooled by the heat exchanger 6 in the slurry storage tank 7 is sprayed into the scrubbing dust removal tower 5. The mass-volume ratio of scrubbing slurry to chlorinated flue gas is 30kg / m³. 3The process further washes away dust from the chlorinated flue gas and reduces its temperature to 80°C. Simultaneously, the resulting washed slurry is fed into slurry storage tank 7, and the generated washed slurry is pumped into the spray liquid inlet of the quench granulator 2 via slurry transfer pump 9. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 80%, the aluminum chloride content in the washed slurry is 0.01%, and the solids content is 3.0%.

[0031] Example 2

[0032] The chlorination flue gas cooling and dust collection system is the same as in Example 1.

[0033] The method for cooling and collecting dust from chlorinated flue gas using the above system includes the following steps:

[0034] High-temperature chlorinated flue gas was introduced into a system containing 25% gaseous titanium tetrachloride with a dust content of 200 g / Nm³. 3 The temperature is 900℃ in the pre-quench cooler 1. Crude titanium tetrachloride is injected into the crude titanium tetrachloride liquid pipe at the top of the pre-quench cooler 1 to cool the chlorinated flue gas to 700℃. The cooled chlorinated flue gas then enters the quench granulator 2. The slurry in the slurry storage tank 7 is transported by the slurry transfer pump 9 to the spray liquid inlet of the quench granulator 2 and sprayed through the centrifugal nozzle at the top of the quench granulator. The centrifugal nozzle rotates at 1000 rpm, and the ratio of the sprayed slurry to the dust-laden high-temperature chlorinated flue gas is 5 kg / m³. 3 The temperature of the chlorinated flue gas is further cooled to 400℃. After cooling, the chlorinated flue gas is sent to a cyclone dust collector 3 for further dust collection to obtain dust material. The dust generated by the rapid cooling granulator 2 is granulated to obtain 0.1-2mm particles, which are sent together with the dust material from the cyclone dust collector 3 into the granulation material silo 4. The chlorinated flue gas after dust removal by the cyclone dust collector 3 is sent to a scrubbing dust removal tower 5. The empty tower gas velocity in the scrubbing dust removal tower 5 is 1.5m / s, and the gas residence time is 6s. A 10% potassium hydroxide solution is sprayed into the inlet of the scrubbing dust removal tower 5, with an addition amount of 300wt.% of the theoretical hydrolysis amount of aluminum chloride in the chlorinated flue gas, to neutralize the aluminum chloride in the flue gas. At the same time, circulating scrubbing slurry cooled by the heat exchanger 6 in the slurry storage tank 7 is sprayed into the scrubbing dust removal tower 5. The mass-volume ratio of scrubbing slurry to chlorinated flue gas is 10kg / m³. 3 The process further washes away dust from the chlorinated flue gas and reduces the flue gas temperature to 125°C. Simultaneously, the resulting washed slurry is fed into the slurry storage tank 7, and the generated washed slurry is pumped into the spray liquid inlet of the quench granulator 2 via the slurry transfer pump 9. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 83%, the aluminum chloride content in the washed slurry is 0.001%, and the solids content is 2.9%.

[0035] Example 3

[0036] The chlorination flue gas cooling and dust collection system is the same as in Example 1.

[0037] The method for cooling and collecting dust from chlorinated flue gas using the above system includes the following steps:

[0038] The volume fraction of gaseous titanium tetrachloride in the high-temperature chlorination flue gas was 32%; the dust content was 190 g / Nm³. 3 The chlorinated flue gas, at a temperature of 950℃, is introduced into the pre-quencher 1. Crude titanium tetrachloride is sprayed into the crude titanium tetrachloride clear liquid pipe at the top of the pre-quencher 1, cooling the chlorinated flue gas to 480℃. The cooled chlorinated flue gas then enters the quencher granulator 2. The slurry in the slurry storage tank 7 is transported by the slurry transfer pump 9 to the spray inlet of the quencher granulator 2 and sprayed through a centrifugal nozzle at the top of the quencher granulator. The centrifugal nozzle rotates at 5000 rpm, and the ratio of the sprayed slurry to the dust-laden high-temperature chlorinated flue gas is 8 kg / m³. 3 The temperature of the chlorinated flue gas is further cooled to 350℃. After cooling, the chlorinated flue gas is sent to a cyclone dust collector 3 for further dust collection to obtain dust material. The dust generated by the rapid cooling granulator 2 is granulated to obtain 0.1-2mm particles, which are sent together with the dust material from the cyclone dust collector 3 into the granulation material silo 4. The chlorinated flue gas after dust removal by the cyclone dust collector 3 is sent to a scrubbing dust removal tower 5. The empty tower gas velocity in the scrubbing dust removal tower 5 is 2.0m / s, and the gas residence time is 4s. A 10% sodium hydroxide solution is sprayed into the air inlet of the scrubbing dust removal tower 5, with the amount added being 100wt.% of the theoretical hydrolysis amount of aluminum chloride in the chlorinated flue gas, to neutralize the aluminum chloride in the flue gas. At the same time, circulating scrubbing slurry cooled by the heat exchanger 6 in the slurry storage tank 7 is sprayed into the scrubbing dust removal tower 5. The mass-volume ratio of scrubbing slurry to chlorinated flue gas is 25kg / m³. 3 The process further washes away dust from the chlorinated flue gas and reduces the flue gas temperature to 100°C. Simultaneously, the resulting washed slurry is fed into the slurry storage tank 7, and the generated washed slurry is pumped into the spray liquid inlet of the quench granulator 2 via the slurry transfer pump 9. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 79%, the aluminum chloride content in the washed slurry is 0.05%, and the solids content is 3.3%.

[0039] Example 4

[0040] The chlorination flue gas cooling and dust collection system is the same as in Example 1.

[0041] The method for cooling and collecting dust from chlorinated flue gas using the above system includes the following steps:

[0042] The volume fraction of gaseous titanium tetrachloride in the high-temperature chlorination flue gas is 30%; the dust content is 150 g / Nm³. 3The chlorinated flue gas, at a temperature of 1000℃, is introduced into the pre-quencher 1. Crude titanium tetrachloride is sprayed into the crude titanium tetrachloride clear liquid pipe at the top of the pre-quencher 1, cooling the chlorinated flue gas to 500℃. The cooled chlorinated flue gas then enters the quencher granulator 2. The slurry in the slurry storage tank 7 is transported by the slurry transfer pump 9 to the spray liquid inlet of the quencher granulator 2 and sprayed through a centrifugal nozzle at the top of the quencher granulator. The centrifugal nozzle rotates at 10000 rpm, and the ratio of the sprayed slurry to the dust-laden high-temperature chlorinated flue gas is 5 kg / m³. 3 The temperature of the chlorinated flue gas is further cooled to 400℃. After cooling, the chlorinated flue gas is sent to a cyclone dust collector 3 for further dust collection to obtain dust material. The dust generated by the rapid cooling granulator 2 is granulated to obtain 0.1-2mm particles, which are sent together with the dust material from the cyclone dust collector 3 into the granulation material silo 4. The chlorinated flue gas after dust removal by the cyclone dust collector 3 is sent to a scrubbing dust removal tower 5. The empty tower gas velocity in the scrubbing dust removal tower 5 is 2.5m / s, and the gas residence time is 3s. Sodium hydroxide with a mass concentration of 10% is sprayed into the air inlet of the scrubbing dust removal tower 5. The amount added is 200wt.% of the theoretical hydrolysis amount of aluminum chloride in the chlorinated flue gas to neutralize the aluminum chloride in the flue gas. At the same time, circulating scrubbing slurry cooled by heat exchanger 6 in the slurry storage tank 7 is sprayed into the scrubbing dust removal tower 5. The mass-volume ratio of scrubbing slurry to chlorinated flue gas is 20kg / m³. 3 The process further washes away dust from the chlorinated flue gas and reduces its temperature to 90°C. Simultaneously, the resulting washed slurry is fed into slurry storage tank 7, and the generated washed slurry is pumped into the spray inlet of the quench granulator 2 via slurry transfer pump 9. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 85%, the aluminum chloride content in the washed slurry is 0.005%, and the solids content is 2.5%.

[0043] Example 5

[0044] The chlorination flue gas cooling and dust collection system is the same as in Example 1.

[0045] The method for cooling and collecting dust from chlorinated flue gas using the above system includes the following steps:

[0046] The volume fraction of gaseous titanium tetrachloride in the high-temperature chlorination flue gas is 40%; the dust content is 50 g / Nm³. 3 The chlorinated flue gas, at a temperature of 800℃, is introduced into the pre-quencher 1. Crude titanium tetrachloride is sprayed into the crude titanium tetrachloride clear liquid pipe at the top of the pre-quencher 1, cooling the chlorinated flue gas to 420℃. The cooled chlorinated flue gas then enters the quencher granulator 2. The slurry in the slurry storage tank 7 is transported by the slurry transfer pump 9 to the spray liquid inlet of the quencher granulator 2 and sprayed through a centrifugal nozzle at the top of the quencher granulator. The centrifugal nozzle rotates at 20,000 rpm, and the ratio of the sprayed slurry to the dust-laden high-temperature chlorinated flue gas is 14 kg / m³. 3The temperature of the chlorinated flue gas is further cooled to 280℃. After cooling, the chlorinated flue gas is sent to a cyclone dust collector 3 for further dust collection to obtain dust material. The dust generated by the rapid cooling granulator 2 is granulated to obtain 0.1-2mm particles, which are sent together with the dust material from the cyclone dust collector 3 into the granulation material silo 4. The chlorinated flue gas after dust removal by the cyclone dust collector 3 is sent to a scrubbing dust removal tower 5. The empty tower gas velocity in the scrubbing dust removal tower 5 is 1.8m / s, and the gas residence time is 5s. A 10% sodium hydroxide solution is sprayed into the air inlet of the scrubbing dust removal tower 5, with the amount added being 120wt.% of the theoretical hydrolysis amount of aluminum chloride in the chlorinated flue gas, to neutralize the aluminum chloride in the flue gas. At the same time, circulating scrubbing slurry cooled by the heat exchanger 6 in the slurry storage tank 7 is sprayed into the scrubbing dust removal tower 5. The mass-volume ratio of scrubbing slurry to chlorinated flue gas is 18kg / m³. 3 The process further washes away dust from the chlorinated flue gas and reduces the flue gas temperature to 105°C. Simultaneously, the resulting washed slurry is fed into the slurry storage tank 7, and the generated washed slurry is pumped into the spray liquid inlet of the quench granulator 2 via the slurry transfer pump 9. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 86%, the aluminum chloride content in the washed slurry is 0.02%, and the solids content is 2.4%.

[0047] Comparative Example 1

[0048] The chlorination flue gas cooling and dust collection system is the same as in Example 1. Using the above system for chlorination flue gas cooling and dust collection, the high-temperature flue gas directly enters the quench granulator 2 without passing through the pre-quench granulator 1. Other operating parameters are completely consistent with Example 5. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 52%, the aluminum chloride content in the washed slurry is 0.04%, and the solids content is 8.6%.

[0049] Comparative Example 2

[0050] The chlorination flue gas cooling and dust collection system is the same as in Example 1. Using the above system for chlorination flue gas cooling and dust collection, the slurry delivery pump 9 is shut down. After pre-quenching in the high-temperature flue gas pre-cooler 1, it bypasses the quench granulator 2 for quenching and granulation, and directly enters the cyclone dust collector 3. Other operating parameters are completely consistent with Example 5. Under these operating conditions, the dust removal efficiency of the quench granulator-cyclone separator is 46%, the aluminum chloride content in the washed slurry is 0.03%, and the solids content is 10.3%.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for cooling and collecting dust from chlorinated flue gas using a chlorinated flue gas cooling and dust collection system, characterized in that, The chlorinated flue gas cooling and dust collection system includes a pre-quench cooler, a quench granulator, a cyclone separator, a granulated material silo, a scrubbing dust removal tower, a heat exchanger, a slurry storage tank, a circulating pump, and a slurry transfer pump. The inlet of the pre-quench cooler is connected to a high-temperature chlorinated flue gas pipeline, the feed inlet of the pre-quench cooler is connected to a crude titanium tetrachloride clear liquid pipeline, and the outlet of the pre-quench cooler is connected to the inlet of the quench granulator. The feed inlet of the quench granulator is connected to the second outlet of the slurry storage tank via a pipeline. A slurry transfer pump is installed on the pipeline between the quench granulator and the slurry storage tank. The outlet of the quench granulator is connected to the inlet of the cyclone separator, and the outlet of the quench granulator is connected to the inlet of the granulated material silo. The discharge port of the cyclone separator is connected to the inlet of the granulation material silo. The air outlet of the cyclone separator is connected to the air inlet of the scrubbing dust removal tower via a pipeline. An alkaline solution pipeline is connected between the cyclone separator and the scrubbing dust removal tower. The air outlet of the scrubbing dust removal tower is connected to the flue gas scrubbing process pipeline. The inlet of the scrubbing dust removal tower is connected to the outlet of the heat exchanger. The outlet of the scrubbing dust removal tower is connected to the inlet of the slurry storage tank. The inlet of the scrubbing dust removal tower is connected to the first outlet of the slurry storage tank via a pipeline. A circulating pump and a heat exchanger are installed on the pipeline between the inlet of the slurry storage tank and the first outlet of the scrubbing dust removal tower. The outlet of the circulating pump is connected to the inlet of the heat exchanger. The process includes the following steps: High-temperature chlorinated flue gas containing dust is fed into a pre-quench cooler, where crude titanium tetrachloride solution is injected. After quenching, the flue gas is then fed into a quench granulator, where it is centrifugally sprayed into a slurry storage tank containing leaching slurry delivered by a slurry pump. Under centrifugal force, the sprayed slurry mixes thoroughly with the chlorinated flue gas, achieving both cooling and dust removal. The centrifugal nozzle speed is 1000 rpm to 30000 rpm, and the ratio of the sprayed leaching slurry to the dust-containing high-temperature chlorinated flue gas is 5 kg / m³. 3 ~20kg / m 3 The solids in the slurry and the dust in the high-temperature flue gas are granulated into granules by a quench granulator. The particle size of the granules formed by the quench granulator is 0.1mm to 2mm, and they enter the granulation material silo. The cooled chlorinated flue gas is sent to a cyclone dust collector, and the dust collected by the cyclone dust collector is also sent to the granulation material silo. The chlorinated flue gas separated by the cyclone dust collector is sent to a scrubbing dust removal tower for condensation and deep dust removal. An alkaline solution is sprayed into the air inlet of the scrubbing dust removal tower. The alkaline solution is a 10% potassium hydroxide solution or a 10% sodium hydroxide solution. The slurry is sprayed into the slurry storage tank through the inlet of the scrubbing dust removal tower and circulated for scrubbing after being cooled by a heat exchanger. The flue gas after scrubbing dust removal is sent to the flue gas scrubbing process. The scrubbing slurry is sent to the slurry storage tank. The gas outlet temperature of the scrubbing dust removal tower is 80℃~125℃, and the liquid-to-gas ratio of the circulating scrubbing process is 10 kg / m³. 3 ~30kg / m 3 The empty tower gas velocity in the scrubbing dust removal tower is 1.5 m / s to 3.0 m / s, the gas residence time is 2 s to 6 s, and the amount of alkali added is 100 wt.% to 300 wt.% of the theoretical amount of aluminum chloride hydrolysis.

2. The method for cooling and collecting dust from chlorinated flue gas using a chlorinated flue gas cooling and dust collection system according to claim 1, characterized in that, The volume fraction of gaseous titanium tetrachloride in the chlorinated flue gas is 20%–40%; the dust content is 50 g / Nm³. 3 ~300g / Nm 3 The temperature ranges from 800℃ to 1100℃.

3. The method for cooling and collecting dust from chlorinated flue gas using a chlorinated flue gas cooling and dust collection system according to claim 1, characterized in that, The crude titanium tetrachloride solution is injected into the crude titanium tetrachloride solution pipe at the top of the pre-cooler to reduce the temperature of the chlorinated flue gas to 400℃~700℃.

4. The method for cooling and collecting dust from chlorinated flue gas using a chlorinated flue gas cooling and dust collection system according to claim 1, characterized in that, The quench granulator uses a rotary nozzle, and the top sprays in washing slurry to reduce the temperature of the chlorinated flue gas to 200℃~400℃.

Images