Titanium tetrachloride tail gas recovery and waste gas treatment system and titanium dioxide production line

Abstract

The application discloses a titanium tetrachloride tail gas recovery and waste gas treatment system and a titanium dioxide production line. The titanium tetrachloride has a low boiling point (about 136 DEG C), and the tail gas entering a tail gas channel can be cooled by a condensing device, so that the titanium tetrachloride in the tail gas is captured again by deep cooling, the liquid titanium tetrachloride is condensed and recovered by a crude titanium tank, and a little uncondensed tail gas is cleaned by acid washing by a wet spraying device, so that the uncondensed tail gas is converted into harmless substances or compounds easy to handle, thereby reducing the loss of raw materials, reducing the amount of waste acid generated in the subsequent acid washing process, and reducing the treatment cost.

Description

Technical Field

[0001] This application relates to the field of titanium dioxide production technology, and in particular to a titanium tetrachloride tail gas recovery and waste gas treatment system and a titanium dioxide production line. Background Technology

[0002] Titanium dioxide (TiO2) is an important and widely used white inorganic pigment, renowned for its excellent optical properties, chemical stability, and hiding power. It has a variety of applications in multiple industries, including but not limited to coatings, plastics, paper, and cosmetics.

[0003] The production of titanium dioxide, especially when using the chlorination process, generates exhaust gases containing titanium tetrachloride (TiCl4) and other byproducts. Direct emission of these exhaust gases without proper treatment can cause serious environmental pollution, including air pollution and acid rain. Therefore, an effective exhaust gas treatment system is crucial for environmental protection and compliance with environmental regulations.

[0004] Currently, the tail gas of titanium tetrachloride is mainly absorbed by direct spraying. However, since titanium tetrachloride reacts with water to produce hydrochloric acid and titanium dioxide precipitate, this not only reduces the yield of titanium tetrachloride but also generates waste acid, increasing the cost of subsequent treatment. Utility Model Content

[0005] The purpose of this application is to provide a titanium tetrachloride tail gas recovery and waste gas treatment system and a titanium dioxide production line, which reduces raw material loss and the amount of waste acid generated in the subsequent pickling process, thereby reducing treatment costs.

[0006] The embodiments of this application can be implemented as follows:

[0007] In the first aspect, this utility model provides a titanium tetrachloride tail gas recovery and waste gas treatment system, including a condensation device, a crude titanium tank and a wet spraying device;

[0008] The condensation device has an exhaust gas passage, the inlet of which is used to allow exhaust gas to pass through, so as to reduce the temperature of the exhaust gas and cause some of the exhaust gas to condense.

[0009] The crude titanium tank is used to recover the condensate generated when the exhaust gas passes through the exhaust channel;

[0010] The wet spraying equipment is connected to the outlet of the exhaust gas channel and is used to purify the exhaust gas after it has passed through the condensation equipment before it is discharged.

[0011] In an optional embodiment, a gas-liquid separator is provided at the outlet of the exhaust gas passage. The gas outlet of the gas-liquid separator is connected to the wet spraying equipment, and the liquid outlet of the gas-liquid separator is connected to the crude titanium tank.

[0012] In an optional embodiment, the crude titanium can is made of stainless steel or carbon steel.

[0013] In an optional embodiment, the titanium tetrachloride tail gas recovery and waste gas treatment system further includes a heat-using device, the condensation device including a heat exchanger, the heat exchanger having the tail gas passage and a heat exchange passage;

[0014] The heat-using equipment is connected to both the inlet and outlet of the heat exchange channel.

[0015] In an optional implementation, the heat-using device is capable of cooling driven by heat.

[0016] In an optional embodiment, the heat-using equipment includes a lithium bromide unit.

[0017] In an optional embodiment, the wet scrubbing equipment includes an acid washing scrubbing tower.

[0018] In an optional embodiment, the titanium tetrachloride tail gas recovery and waste gas treatment system further includes a booster device, the negative pressure side of which is connected to the purified gas outlet of the wet spraying device.

[0019] In an optional implementation, the pressurization device includes a fan.

[0020] Secondly, this utility model provides a titanium dioxide production line, including the titanium tetrachloride tail gas recovery and waste gas treatment system described in any of the foregoing embodiments.

[0021] The beneficial effects of the embodiments of this application include, for example:

[0022] Taking advantage of the low boiling point of titanium tetrachloride (approximately 136°C), the exhaust gas entering the exhaust gas channel can be cooled by a condensation device, and the titanium tetrachloride in the exhaust gas can be captured by secondary cryogenic treatment. The titanium tetrachloride is condensed into liquid and recovered through a crude titanium tank. The wet spraying device then uses acid washing to purify the small amount of uncondensed exhaust gas, converting it into harmless substances or easily treatable compounds. This reduces raw material loss and the amount of waste acid generated in the subsequent acid washing process, thereby reducing treatment costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1This is a schematic diagram of the titanium tetrachloride tail gas recovery and waste gas treatment system according to an embodiment of this application.

[0025] Icons: 1-Condensation equipment; 2-Crude titanium tank; 3-Pickling spray tower; 4-Heat equipment; 5-Pressure booster equipment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] refer to Figure 1 This application discloses a titanium dioxide production line, which includes a refining system, a silicon removal system, and a titanium tetrachloride tail gas recovery and waste gas treatment system.

[0034] The titanium tetrachloride tail gas from the refining system and the silicon removal system is treated by the titanium tetrachloride tail gas recovery and waste gas treatment system to meet environmental protection requirements.

[0035] In this embodiment, the titanium tetrachloride tail gas recovery and waste gas treatment system includes a condensation device 1, a crude titanium tank 2, and a wet spraying device.

[0036] The condensation device 1 has an exhaust gas passage. The inlet of the exhaust gas passage is used to allow exhaust gas to pass through, so as to reduce the temperature of the exhaust gas and condense part of the exhaust gas.

[0037] The crude titanium tank 2 is used to recover the condensate generated when passing through the exhaust gas passage;

[0038] The wet spray equipment is connected to the outlet of the exhaust gas channel to purify the exhaust gas after it has passed through the condenser 1 before it is discharged.

[0039] In this way, taking advantage of the low boiling point of titanium tetrachloride (approximately 136°C), the exhaust gas entering the exhaust gas channel can be cooled by the condensation device 1, and the titanium tetrachloride in the exhaust gas can be captured by secondary cryogenic treatment. The titanium tetrachloride is condensed into liquid and recovered through the crude titanium tank 2. The wet spraying device then uses acid washing to purify the small amount of uncondensed exhaust gas, converting it into harmless substances or easily treated compounds, reducing raw material loss and the amount of waste acid generated in the subsequent acid washing process, thus reducing treatment costs.

[0040] The crude titanium tank 2 has good sealing performance to prevent secondary pollution caused by the volatilization of titanium tetrachloride. The material of the crude titanium tank 2 includes stainless steel (especially molybdenum-containing stainless steel) or carbon steel to ensure the durability of the crude titanium tank 2.

[0041] A gas-liquid separator is installed at the outlet of the exhaust gas passage. The gas outlet of the gas-liquid separator is connected to a wet spraying device, and the liquid outlet of the gas-liquid separator is connected to the crude titanium tank 2.

[0042] The gas-liquid separator primarily utilizes gravity to separate condensate from the gas phase. Its working principle is as follows: when the exhaust gas containing condensate droplets enters the separator, the heavier droplets sink under gravity and flow into the coarse titanium tank 2 through the bottom outlet pipe; while the lighter gas phase continues to rise and is guided to the wet spray equipment through the top outlet pipe. Furthermore, the gas-liquid separator has a simple structure, low cost, and is easy to maintain.

[0043] The titanium tetrachloride tail gas recovery and waste gas treatment system also includes a heat-using device 4. The condensing device 1 includes a heat exchanger, which has a tail gas passage (i.e., tube side) and a heat exchange passage (i.e., shell side). The heat-using device 4 is connected to both the inlet and outlet of the heat exchange passage.

[0044] The heat absorbed by the heat exchanger can then be transferred to the heat-using equipment 4 for use, such as preheating boiler water, heating raw materials or media required for chemical reactions, or maintaining the temperature conditions required for certain processes. This reduces the demand for external energy, lowers production costs and environmental impact, thereby improving the system's energy efficiency and reducing overall energy consumption.

[0045] The heat-using device 4 can perform refrigeration driven by heat, which can not only effectively utilize the waste heat in the exhaust gas, but also provide a continuous supply of cold water (e.g., 7°C cold water) to the heat exchanger, ensuring that the heat exchanger is always in a high-efficiency operating state.

[0046] The heat-using equipment 4 includes a lithium bromide unit. The working principle of the lithium bromide unit is as follows: 1. Heat recovery: The lithium bromide unit operates through its internal components such as an evaporator, absorber, generator, and condenser. When the exhaust gas passes through the heat exchanger, the heat it releases is absorbed by the medium within the heat exchanger (usually water or another heat-conducting fluid). This heat-absorbing medium enters the generator of the lithium bromide unit, where the heat drives the lithium bromide solution to concentrate and release water vapor. The water vapor is then cooled into liquid water in the condenser and flows to the evaporator. 2. Cold water supply: In the evaporator, the liquid water absorbs heat from the external circulating water (i.e., the cold water supplied to the heat exchanger) and evaporates, thereby cooling this circulating water. The cooled circulating water (cold water) is pumped back to the heat exchanger to exchange heat with the high-temperature exhaust gas, absorbing heat from the exhaust gas and forming a closed-loop cycle.

[0047] Therefore, lithium bromide absorption chillers (LiBBS chillers for short) can effectively utilize waste heat to generate cooling capacity, making this system ideal for recovering waste heat generated in industrial processes. LiBBS chillers are used to recover heat from heat exchangers and supply chilled water to the heat exchangers to continue absorbing heat from exhaust gases. This not only achieves efficient energy utilization but also brings significant economic and environmental benefits, reducing costs and increasing yield.

[0048] In addition, in some embodiments, absorption chillers or the like can be used to achieve cyclic heat absorption and cooling with the heat exchanger.

[0049] Wet scrubbing equipment includes, but is not limited to, acid pickling spray tower 3. The pump-driven system design of acid pickling spray tower 3 is a common configuration in industrial waste gas treatment. It uses a pump to deliver absorbent liquid (such as an alkaline solution or other chemical absorbent) to nozzles at the top or middle of the spray tower, spraying it down in a mist form to fully contact the rising waste gas, thereby achieving the purpose of purifying the waste gas. Its working principle is as follows: exhaust gas is introduced into the bottom or side of the spray tower through pipelines. The pump draws absorbent liquid from the storage tank and delivers it to the nozzles at the top or middle of the spray tower through high-pressure pipelines. The nozzles spray the absorbent liquid evenly in the form of fine droplets, allowing the droplets to fully contact the waste gas inside the tower, resulting in a chemical reaction that neutralizes the acidic gases. After spray absorption, the waste gas continues to flow upwards, entering the demister section. At this stage, a demister is used to remove droplets carried in the waste gas, preventing them from being directly emitted into the atmosphere and causing secondary pollution. The treated waste gas is then discharged into the atmosphere through the top chimney, meeting emission standards. Some of the spray liquid will be recycled and pumped back into the spray system for reuse, while the waste liquid containing a large amount of reaction products needs to be further treated to meet environmental protection requirements.

[0050] Of course, besides the acid washing spray tower 3, wet scrubbing equipment can also include wet scrubbers, electrostatic precipitators, chemical absorption towers, membrane separation technology, and catalytic converters, which can also effectively remove titanium tetrachloride and other acidic substances from exhaust gases. Depending on the specific operating conditions and treatment requirements, single equipment or a combination of multiple equipment can be selected to achieve efficient, economical, and environmentally friendly exhaust gas treatment goals.

[0051] The titanium tetrachloride tail gas recovery and waste gas treatment system also includes a booster device 5, whose negative pressure side is connected to the purified gas outlet of the wet scrubbing equipment. The booster device 5 is mainly used to increase the pressure of the purified gas discharged from the acid washing scrubbing tower 3, so that the treated clean gas can be transported to where it is needed, such as being discharged into a higher chimney, transported over long distances, or used for further treatment equipment.

[0052] The booster unit 5 includes a fan that provides sufficient pressure boost to meet delivery requirements while maintaining high efficiency. It starts quickly, is easy to operate, and requires no complex preheating or adjustment processes. Its relatively simple structure makes it easy to maintain, resulting in a low failure rate and reduced maintenance costs during long-term operation. Furthermore, the airflow and pressure can be easily adjusted according to different process requirements, making it highly adaptable.

[0053] Of course, in some embodiments, the purified gas outlet of the pickling spray tower 3 is pressurized. In addition to commonly used fans and blowers, there are other types of equipment that can achieve similar functions. For example, compressors, turbochargers, etc.

[0054] In summary, this application discloses a titanium tetrachloride tail gas recovery and waste gas treatment system and a titanium dioxide production line. Utilizing the low boiling point of titanium tetrachloride (approximately 136°C), the tail gas entering the tail gas channel can be cooled by the condensation device 1, and the titanium tetrachloride in the tail gas can be captured by secondary cryogenic treatment. The titanium tetrachloride is condensed into a liquid and recovered through the crude titanium tank 2. The wet spraying device then uses acid washing to purify the small amount of uncondensed tail gas, converting it into harmless substances or easily treatable compounds. The condensate is recovered through the crude titanium tank 2, reducing raw material loss and the amount of waste acid generated in the subsequent acid washing process, thus reducing processing costs.

[0055] Finally, it should be noted that in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0056] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A titanium tetrachloride tail gas recovery and waste gas treatment system, characterized in that, It includes a condensation device (1), a crude titanium tank (2), and a wet spraying device; The condensation device (1) has an exhaust gas passage, the inlet of which is used to allow exhaust gas to pass through, so as to reduce the temperature of the exhaust gas and condense part of the exhaust gas. The crude titanium tank (2) is used to recover the condensate generated when passing through the exhaust gas channel; The wet spraying equipment is connected to the outlet of the exhaust gas channel and is used to purify the exhaust gas that has passed through the condensation equipment (1) before discharging it.

2. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 1, characterized in that, A gas-liquid separator is installed at the outlet of the exhaust gas passage. The gas outlet of the gas-liquid separator is connected to the wet spraying equipment, and the liquid outlet of the gas-liquid separator is connected to the crude titanium tank (2).

3. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 1, characterized in that, The crude titanium can (2) is made of stainless steel or carbon steel.

4. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 1, characterized in that, The titanium tetrachloride tail gas recovery and waste gas treatment system also includes a heat-using device (4), and the condensation device (1) includes a heat exchanger, which has the tail gas passage and a heat exchange passage. The heat-using equipment (4) is connected to both the inlet and outlet of the heat exchange channel.

5. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 4, characterized in that, The heat-using device (4) is capable of cooling through heat.

6. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 5, characterized in that, The heat-using equipment (4) includes a lithium bromide unit.

7. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 1, characterized in that, The wet spraying equipment includes an acid washing spray tower (3).

8. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 1, characterized in that, The titanium tetrachloride tail gas recovery and waste gas treatment system also includes a booster device (5), the negative pressure side of which is connected to the purified gas outlet of the wet spraying equipment.

9. The titanium tetrachloride tail gas recovery and waste gas treatment system according to claim 8, characterized in that, The booster device (5) includes a fan.

10. A titanium dioxide production line, characterized in that, The system includes the titanium tetrachloride tail gas recovery and waste gas treatment system according to any one of claims 1-9.

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