Furnace temperature control method for fluidized chlorination reaction

Abstract

The invention provides a furnace temperature control method for fluidization chlorination reaction, which relates to the technical field of chlorination, and is characterized in that a furnace temperature control system is arranged and is connected with a reaction section of a chlorination furnace from the side surface, and chloride fog drops are directly sprayed into different positions of the reaction section to control the temperature of the chlorination reaction. When the temperature in the furnace is over-high, liquid chloride is atomized in the atomizing tower and then is introduced into the furnace from the side surface by taking nitrogen as carrier gas to directly cool the over-temperature reaction area; and when the temperature in the furnace is normal, the atomizing tower and the atomized gas entering the furnace can be closed. According to the method, chloride fog drops are directly sprayed into the reaction area in the furnace from the side surface, on one hand, the temperature of an overtemperature area can be directly adjusted, the fluctuation range of the reaction temperature can be controlled within 10 DEG C, and the situation that fluidization is influenced by melting of chlorides such as calcium and magnesium caused by overtemperature is avoided; the heat transfer is more uniform, and the influence on the chlorination reaction due to over-low local furnace temperature caused by over-concentrated liquid injection during cooling is avoided.

Description

Technical Field

[0001] This invention relates to the field of chlorination experimental equipment technology, specifically a furnace temperature control method for fluidized bed chlorination reactions. Background Technology

[0002] Fluidized bed chlorination is a highly efficient metallurgical and chemical process that uses chlorin or hydrogen chloride as a chlorinating agent in a fluidized bed reactor to react with solid materials (usually metal oxides) at a certain temperature to produce gaseous metal chlorides. However, the chlorination reaction is strongly exothermic. To achieve the required process conditions, it is necessary to uniformly control the furnace temperature. This is to prevent high temperatures from causing alkaline earth metal chlorides such as calcium chloride and magnesium chloride to melt, and also to prevent uneven heat transfer from leading to excessively low temperatures in some areas, resulting in iron-sodium eutectic.

[0003] To control the temperature of the chlorination reaction, patent CN 105271381 A discloses a low-temperature boiling chlorination furnace and a temperature-controllable low-temperature boiling chlorination method. By introducing liquid TiCl4 into the bottom of the reaction section of the low-temperature boiling chlorination furnace, the temperature of the reaction section is controlled within a predetermined temperature range. However, because the gas inlet is at the bottom of the bed, the bed pressure is relatively high, which can lead to blockage of the TiCl4 inlet, hindering the transport of liquid TiCl4. Patent CN 109052459A discloses a chlorination furnace for producing TiCl4 and its furnace temperature control method. This method controls the furnace temperature below 650℃ by using top-spray cooling, which effectively lowers the temperature. However, in fluidized bed chlorination applications, both top-spray and bottom-spray cooling methods are prone to uneven heat transfer, leading to excessively low local temperatures. This affects the fluidization process and the chlorination reaction. Furthermore, because the chlorides of iron, sodium, calcium, and magnesium have low boiling points, they easily form eutectics at low temperatures. To avoid eutectics, the content of iron, sodium, calcium, and magnesium in the raw materials needs to be strictly controlled, which significantly increases the raw material processing costs and limits the application of the chlorination process. Therefore, a method that can uniformly control the temperature of the reaction section is needed to solve these problems. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention proposes a furnace temperature control method for fluidized bed chlorination reactions. The technical solution of this invention is as follows:

[0005] 1. A method for controlling the furnace temperature in a fluidized bed chlorination reaction, wherein the furnace temperature is controlled by spraying liquid chloride droplets from the side into different areas of the reaction section inside the furnace through a furnace temperature control system connected to the chlorination furnace.

[0006] 2. Furthermore, the furnace temperature control system includes an atomizing tower (3), a delivery pump (9), an atomizing nozzle (6), a gas delivery pipeline (1, 5), and a liquid circulation pipeline (4, 10). The atomizing tower is equipped with a pressure sensor and a temperature sensor, and a liquid level sensor is provided at the bottom. The atomizing tower (3) is connected to the chlorination furnace through an atomizing gas delivery pipe (1).

[0007] 3. Furthermore, the gas delivery pipeline system (1, 5) includes a nitrogen inlet pipe (5) and an atomizing gas delivery pipe (1). Nitrogen is continuously introduced into the nitrogen inlet pipe to ensure that the pressure inside the atomizing tower is maintained at a certain level and is higher than the pressure inside the furnace, with a pressure difference of 0.1 ~ 0.15 MPa.

[0008] 4. Furthermore, the bottom of the atomizing tower (3) is connected to the atomizing nozzle inside the tower via a delivery pump (9), a circulation control valve (12), and a liquid circulation pipeline (4, 10). After passing through the atomizing nozzle (6), the chloride at the bottom of the tower forms atomized droplets inside the tower. The nitrogen gas introduced into the nitrogen gas inlet pipe mixes with the atomized droplets and then enters the furnace through the atomizing gas delivery pipe (1) and the control valve (2). The horizontal atomizing nozzle on the side wall of the atomizing tower is at the same height as the atomizing gas delivery pipe.

[0009] 5. Furthermore, the delivery pump (9) is connected to the chiller via the cooling control valve (7) and the cooling circulation pipe (8). The liquid cooled by the chiller enters the atomizing tower (3) through the inlet (11). The temperature of the liquid chloride is adjusted to ≤ 0 ℃ in conjunction with the temperature sensor inside the atomizing tower. The inlet (11) is connected to the storage tank and can be used with the liquid level sensor inside the tower to control the liquid chloride level at the bottom of the atomizing tower. The distance between the liquid level inside the tower and the lowest position atomizing nozzle is ≥ 600 mm.

[0010] 6. Preferably, the diameter of the atomizing gas delivery pipe furnace is 50-100 mm, the outer part of the pipeline is made of stainless steel, and the furnace interior is made of corundum, with the two parts connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed spray holes on the surface, and the nozzle diameter is 5-10 mm. The vertical distance of the atomizing gas delivery pipe is 1-1.5 m, and its position is on the same straight line as the cross-sectional diameter of the chlorination furnace.

[0011] 7. All valves in this invention are pneumatic regulating valves, and all valves, sensors, and delivery pumps within the device are electrically connected to the DCS control system. After the furnace is started, when the temperature exceeds the process requirements, the delivery pump is turned on, and nitrogen gas delivers the atomized chloride into the furnace. Based on the reaction temperature rise in different parts of the furnace, the opening of each inlet valve is adjusted to control the amount of atomized gas entering at different locations within the furnace.

[0012] Compared with existing technologies, the beneficial effects of this invention are that it connects the furnace temperature control system to different areas of the chlorination furnace reaction section from the side, and controls the reaction temperature by spraying a certain amount of liquid chloride droplets into the furnace through an atomizing gas delivery pipe. Compared with direct top or bottom spraying, this method has less thermal shock to the furnace, more uniform heat transfer, and avoids excessively low temperatures at the top or bottom of the furnace, ensuring the stability of the fluidization state and the chlorination reaction. Side air intake can directly cool the overheated areas of the reaction section, avoiding the situation where cooling the core area leads to excessively low temperatures in other parts of the furnace. At the same time, side air intake can also improve the fluidization uniformity in the furnace, avoiding channeling or dead zones caused by excessively large local bubbles. Through the method provided by this invention, the temperature of each part of the furnace can be precisely controlled, and the temperature fluctuation of each part of the reaction section in the furnace can be controlled within 10°C. Furthermore, side air intake improves the fluidization state, and some raw materials with high iron, sodium, calcium, and magnesium content can also be used in the chlorination process, broadening the application range of the chlorination process. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a furnace temperature control method for a fluidized bed chlorination reaction according to this patent.

[0014] The following are marked in the figure: atomizing gas delivery pipe (1), air inlet control valve (2), atomizing tower (3), liquid circulation pipeline (4), nitrogen inlet pipe (5), atomizing nozzle (6), cooling control valve (7), cooling circulation pipe (8), delivery pump (9), liquid circulation pipeline (4, 10), liquid inlet (11), circulation control valve (12).

[0015] Figure 2 This is a diagram showing the distribution of nozzles at the top of the atomizing gas delivery pipe for a furnace temperature control method in a fluidized chlorination reaction according to this patent.

[0016] Figure 3 This is the time-reaction temperature curve of Example 1 of a furnace temperature control method for fluidized bed chlorination reaction according to this patent.

[0017] Figure 4 This is the time-reaction temperature curve of Example 2 of a furnace temperature control method for fluidized bed chlorination reaction according to this patent.

[0018] Figure 5 This is the time-reaction temperature curve of Example 3 of a furnace temperature control method for fluidized bed chlorination reaction according to this patent.

[0019] Figure 6 This is the time-reaction temperature curve of Example 4 of a furnace temperature control method for fluidized bed chlorination reaction according to this patent.

[0020] Figure 7 This is the time-reaction temperature curve of Example 5 of the furnace temperature control method for fluidized bed chlorination reaction of this patent. Detailed Implementation

[0021] The principles and features of this patent will be described below with reference to the accompanying drawings in the embodiments of this patent. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Therefore, all designs, operating conditions, parameters, etc., made on the basis of this patent without departing from the subject of this invention are within the scope of protection of this invention.

[0022] This invention provides a furnace temperature control method for fluidized bed chlorination reactions; please refer to [the relevant documentation]. Figure 1 Before starting the chlorination furnace, replenish the liquid level in the tower through the liquid inlet (11), turn on the delivery pump (9), and open the cooling control valve (8) to cool the liquid in the tower. The liquid temperature in the atomization tower should be ≤ 0 ℃. This way, the temperature of the atomized droplets will be lower, which is beneficial for cooling the furnace. The specific temperature can be adjusted according to the actual situation.

[0023] When the chlorination furnace is started, the pressure difference between the atomizing tower and the furnace is maintained at 0.1 ~ 0.15 MPa through the nitrogen inlet pipe (5). When the furnace needs to be cooled down, the high-pressure atomized gas (composed of high-pressure nitrogen and atomized liquid chloride) in the tower can be quickly injected into the furnace. While playing a cooling role, the high pressure difference can also prevent the atomized gas delivery pipe from being blocked.

[0024] It should be understood that the chlorination reaction is an exothermic reaction. After the reaction starts, the temperature inside the furnace will increase rapidly. Due to the influence of low-temperature raw materials and low-temperature chlorine gas at the bottom of the furnace, the temperature distribution inside the furnace will be uneven, making it impossible to achieve the requirement of precise control of the reaction temperature and affecting the selectivity of chlorination. In this invention, atomizing gas inlet pipes are set at different positions on the side wall of the reaction section. The amount of atomizing gas can be controlled by controlling the opening of the gas inlet control valve, thereby controlling the reaction temperature at different positions inside the furnace. The specific implementation method is as follows: After the reaction starts, the DCS control system detects the temperature at different positions inside the furnace, turns on the delivery pump, and opens the circulation control valve (12). Liquid chloride forms atomized gas through the atomizing nozzle and mixes with nitrogen gas. Nitrogen gas is used as the carrier gas to deliver it into the furnace. Liquid chloride evaporates and absorbs heat in the furnace, reducing the temperature inside the furnace. The opening of the gas inlet control valve is controlled according to the temperature at different positions inside the furnace. This invention can control the chlorination reaction temperature at 10°C. If the reaction temperature at a certain location exceeds this range, the valve opening on the atomizing gas inlet pipe at the corresponding location needs to be increased to increase the atomizing gas intake and reduce the reaction temperature. If the reaction temperature at a certain location is lower than this range, the valve opening on the atomizing gas inlet pipe at the corresponding location needs to be reduced or even closed to reduce the atomizing gas intake at that reaction location.

[0025] Furthermore, in order to ensure that the atomizing nozzles (6) of the atomizing tower (3) are not submerged by the liquid level at the bottom of the tower, a liquid level sensor is installed in the atomizing tower to control the liquid level height in the tower. While meeting the liquid level required for the atomizing tower spray, the distance between the liquid level and the atomizing nozzle below the lowest position is controlled by the liquid inlet (11) connected to the storage tank to be ≥ 600 mm, so as to prevent the liquid level from being too high and affecting the amount of atomizing gas in the tower.

[0026] The atomizing gas delivery pipe has a diameter of 50-100 mm. The outer part of the pipe is made of stainless steel, while the inner part is made of corundum. The two parts are connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles on the surface. The nozzle diameter is 5-10 mm. The vertical distance of the atomizing gas delivery pipe is 1-1.5 m, and its position is on the same straight line as the cross-sectional diameter of the chlorination furnace. By rationally designing the pipe diameter, nozzles, and pipe spacing, it is ensured that the atomizing gas can be uniformly and stably injected into different positions of the reaction section inside the furnace.

[0027] The method for uniformly controlling the temperature of the reaction section according to the present invention will be further described below with reference to specific embodiments. Taking a vanadium-containing iron slag as raw material for low-temperature chlorination reaction as an example, the reaction temperature of this reaction is 550 ~ 650 ℃, and the optimal temperature range is 600 ± 10 ℃.

[0028] Example 1

[0029] This embodiment uses four atomizing gas delivery pipes to control the temperature of different parts of the reaction section. The chlorination furnace used in the experiment has an inner diameter of 1 m, an atomizing tower diameter of 0.5 m, and a reaction section height of 5 m. It has top feeding, and four sets of atomizing gas delivery pipes are installed on the side of the reaction section from top to bottom, named 01, 02, 03, and 04 respectively. Four temperature measuring points are set inside the furnace from top to bottom, namely 001, 002, 003, and 004. The diameter of the atomizing gas delivery pipes is 50 mm, with the outer part made of stainless steel and the inner part made of corundum, connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles of 7.5 mm diameter. The vertical distance between the atomizing gas delivery pipes is 1.5 m, and their positions are aligned with the cross-sectional diameter of the chlorination furnace. DCS data during the reaction process is exported, with one point exported every 5 seconds, and a time-reaction temperature curve is plotted.

[0030] Before starting the furnace, turn on the delivery pump, close the circulation control valve, and open the cooling control valve to lower the temperature of VOCl3 in the atomization tower to 0 ℃. Once the required temperature is reached, turn off the delivery pump and the cooling control valve. During this period, introduce nitrogen gas into the atomization tower to maintain a pressure difference of 0.15 MPa between the atomization tower and the chlorination furnace.

[0031] After the furnace is started, the overall temperature inside the furnace begins to rise, and the temperature in the upper part of the reaction section rises rapidly. The experiment is started about 5 minutes before the temperature of 001 reaches 650 ℃. At this time, the delivery pump and circulation control valve are turned on, and the air inlet control valves on the atomizing gas delivery pipes 01, 02, 03 and 04 are gradually opened. The experimental time and valve opening are compared in Table 1 below. Since the reaction temperature at the top of the reaction section increases rapidly, the air inlet control valve of the atomizing gas delivery pipe 01 is opened at the largest degree, which is 50% when 5 to 12 minutes.

[0032] To reduce the reaction temperature as quickly as possible, after 12 minutes, the openings of the atomizing tubes 01, 02, 03, and 04 were increased to 75%, 55%, 45%, and 35%, respectively.

[0033] At 16 minutes, the furnace bottom temperature first drops to about 600 ℃, and the opening of the air intake control valves of atomizing gas delivery pipes 03 and 04 is reduced to 30% and 20% respectively, and the valve openings of atomizing gas delivery pipes 01 and 02 are reduced to 55% and 45% respectively.

[0034] After 24 minutes, the temperature in the upper part of the reaction section drops to 600~610℃. The valve openings of atomizing gas delivery pipes 01 and 02 are reduced to 40% and 30% respectively, while the openings of 03 and 04 remain unchanged. At this time, the temperature range inside the furnace is stable, and the temperature of each part of the reaction section is controlled between 600~610℃ with fluctuations within 10℃, which meets the optimal control range required by the process.

[0035] After the experiment, the chlorination furnace was fed normally, and the liquid level in the tower decreased. The distance from the lowest atomizing gas delivery pipe was ≥600 mm. Vanadium oxychloride was then added to the tower through the storage tank to restore the liquid level. Simultaneously, the delivery pump was started, and the cooling control valve was opened, maintaining a 20% valve opening. Once the temperature of vanadium oxychloride in the tower was ≤0 ℃, the delivery pump was restarted, and the cooling control valve was closed.

[0036] Table 1 Intake control valve opening

[0037] Experimental period Atomizing gas delivery pipe 01 Atomizing gas delivery pipe 02 Atomizing gas delivery pipe 03 Atomizing gas delivery pipe 04 0~5 min 0% 0% 0% 0% 5~12 min 50% 40% 35% 30% 12~16 min 75% 55% 45% 35% 16~24 min 55% 45% 30% 20% 24~32 min 40% 30% 30% 20%

[0038] Example 2

[0039] This embodiment uses four atomizing gas delivery pipes to control the temperature of different parts of the reaction section. The chlorination furnace used in the experiment has an inner diameter of 1 m, an atomizing tower diameter of 0.5 m, and a reaction section height of 5 m. It has top feeding, and four sets of atomizing gas delivery pipes are installed on the side of the reaction section from top to bottom, named 01, 02, 03, and 04 respectively. Four temperature measuring points are set inside the furnace from top to bottom, namely 001, 002, 003, and 004. The diameter of the atomizing gas delivery pipes is 75 mm, with the outer part made of stainless steel and the inner part made of corundum, connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles of 10 mm diameter. The vertical distance between the atomizing gas delivery pipes is 1 m, and their positions are aligned with the cross-sectional diameter of the chlorination furnace. DCS data during the reaction process is exported, with one point exported every 5 seconds, and a time-reaction temperature curve is plotted.

[0040] Before starting the furnace, turn on the delivery pump, close the circulation control valve, and open the cooling control valve to lower the temperature of VOCl3 in the atomization tower to -10 ℃. Once the required temperature is reached, turn off the delivery pump and the cooling control valve. During this period, introduce nitrogen gas into the atomization tower to maintain a pressure difference of 0.125 MPa between the atomization tower and the chlorination furnace.

[0041] After the furnace is started, the overall temperature inside the furnace begins to rise, and the temperature in the upper part of the reaction section rises rapidly. The experiment is started about 5 minutes before the temperature of 001 reaches 650 ℃. At this time, the delivery pump and circulation control valve are turned on, and the air inlet control valves on the atomizing gas delivery pipes 01, 02, 03 and 04 are gradually opened. The experimental time and valve opening are compared in Table 2 below. Since the reaction temperature at the top of the reaction section increases rapidly, the air inlet control valve of the atomizing gas delivery pipe 01 has the largest opening, which is 45% when 5 to 12 minutes.

[0042] To reduce the reaction temperature as quickly as possible, after 12 minutes, the openings of the atomizing tubes 01, 02, 03, and 04 were increased to 70%, 50%, 40%, and 35%, respectively.

[0043] At 17 minutes, the furnace bottom temperature first drops to about 600 ℃. The opening of the air intake control valves of atomizing gas delivery pipes 03 and 04 is reduced to 25% and 20%, respectively, and the valve openings of atomizing gas delivery pipes 01 and 02 are reduced to 50% and 40%, respectively.

[0044] After 24 minutes, the temperature in the upper part of the reaction section drops to 600~610℃. The valve openings of atomizing gas delivery pipes 01 and 02 are reduced to 40% and 30% respectively, while the openings of 03 and 04 remain unchanged. At this time, the temperature range inside the furnace is stable, and the temperature of each part of the reaction section is controlled between 600~610℃ with fluctuations within 10℃, which meets the optimal control range required by the process.

[0045] After the experiment, the chlorination furnace was fed normally, and the liquid level in the tower decreased. The distance from the lowest atomizing gas delivery pipe was ≥600 mm. Vanadium oxychloride was then added to the tower through the storage tank to restore the liquid level. Simultaneously, the delivery pump was started, and the cooling control valve was opened, maintaining a 20% valve opening. Once the temperature of vanadium oxychloride in the tower was ≤0 ℃, the delivery pump was restarted, and the cooling control valve was closed.

[0046] Table 2 Intake Control Valve Opening

[0047] Experimental period Atomizing gas delivery pipe 01 Atomizing gas delivery pipe 02 Atomizing gas delivery pipe 03 Atomizing gas delivery pipe 04 0~5 min 0% 0% 0% 0% 5~12 min 45% 35% 30% 25% 12~17 min 70% 50% 40% 35% 17~24 min 50% 40% 25% 20% 24~32 min 40% 30% 25% 20%

[0048] Example 3

[0049] This embodiment uses four atomizing gas delivery pipes to control the temperature of different parts of the reaction section. The chlorination furnace used in the experiment has an inner diameter of 1 m, an atomizing tower diameter of 0.5 m, and a reaction section height of 5 m. It has top feeding, and four sets of atomizing gas delivery pipes are installed on the side of the reaction section from top to bottom, named 01, 02, 03, and 04 respectively. Four temperature measuring points are set inside the furnace from top to bottom, namely 001, 002, 003, and 004. The diameter of the atomizing gas delivery pipes is 100 mm, with the outer part made of stainless steel and the inner part made of corundum, connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles of 5 mm diameter. The vertical distance between the atomizing gas delivery pipes is 1.25 m, and their positions are aligned with the cross-sectional diameter of the chlorination furnace. DCS data during the reaction process is exported, with one point exported every 5 seconds, and a time-reaction temperature curve is plotted.

[0050] Before starting the furnace, turn on the delivery pump, close the circulation control valve, and open the cooling control valve to lower the temperature of VOCl3 in the atomization tower to -20 ℃. Once the required temperature is reached, turn off the delivery pump and the cooling control valve. During this period, introduce nitrogen gas into the atomization tower to maintain a pressure difference of 0.1 MPa between the atomization tower and the chlorination furnace.

[0051] After the furnace is started, the overall temperature inside the furnace begins to rise, and the temperature in the upper part of the reaction section rises rapidly. The experiment is started about 5 minutes before the temperature of 001 reaches 650 ℃. At this time, the delivery pump and circulation control valve are turned on, and the air inlet control valves on the atomizing gas delivery pipes 01, 02, 03, and 04 are gradually opened. The experimental time and valve opening are compared in Table 3 below. Because the reaction temperature at the top of the reaction section increases rapidly, the air inlet control valve of the atomizing gas delivery pipe 01 has the largest opening, which is 40% when the temperature is between 5 and 12 minutes.

[0052] To reduce the reaction temperature as quickly as possible, after 12 minutes, the openings of the atomizing tubes 01, 02, 03, and 04 were increased to 65%, 45%, 40%, and 35%, respectively.

[0053] At 19 minutes, the furnace bottom temperature first dropped to about 600 ℃, and the opening of the air intake control valves of atomizing gas delivery pipes 03 and 04 was reduced to 25% and 20%, respectively, and the valve openings of atomizing gas delivery pipes 01 and 02 were reduced to 45% and 35%, respectively.

[0054] After 25 minutes, the temperature in the upper part of the reaction section drops to 600-610℃. The valve openings of atomizing gas delivery pipes 01 and 02 are reduced to 35% and 30% respectively, while the openings of 03 and 04 remain unchanged. At this point, the temperature range inside the furnace is stable, and the temperature of each part of the reaction section is controlled between 600-610℃ with fluctuations within 10℃, which meets the optimal control range required by the process.

[0055] After the experiment, the chlorination furnace was fed normally, and the liquid level in the tower decreased. The distance from the lowest atomizing gas delivery pipe was ≥600 mm. Vanadium oxychloride was then added to the tower through the storage tank to restore the liquid level. Simultaneously, the delivery pump was started, and the cooling control valve was opened, maintaining a 20% valve opening. Once the temperature of vanadium oxychloride in the tower was ≤0 ℃, the delivery pump was restarted, and the cooling control valve was closed.

[0056] Table 3 Intake control valve opening

[0057] Experimental period Atomizing gas delivery pipe 01 Atomizing gas delivery pipe 02 Atomizing gas delivery pipe 03 Atomizing gas delivery pipe 04 0~5 min 0% 0% 0% 0% 5~12 min 40% 30% 30% 25% 12~19 min 65% 45% 40% 35% 19~25 min 45% 35% 25% 20% 25~32 min 35% 30% 25% 20%

[0058] Example 4

[0059] This embodiment uses four atomizing gas delivery pipes to control the temperature of different parts of the reaction section. The chlorination furnace used in the experiment has an inner diameter of 1 m, an atomizing tower diameter of 0.5 m, and a reaction section height of 5 m. It has top feeding, and four sets of atomizing gas delivery pipes are installed on the side of the reaction section from top to bottom, named 01, 02, 03, and 04 respectively. Four temperature measuring points are set inside the furnace from top to bottom, namely 001, 002, 003, and 004. The diameter of the atomizing gas delivery pipes is 50 mm, with the outer part made of stainless steel and the inner part made of corundum, connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles of 7.5 mm diameter. The vertical distance between the atomizing gas delivery pipes is 1.5 m, and their positions are aligned with the cross-sectional diameter of the chlorination furnace. DCS data during the reaction process is exported, with one point exported every 5 seconds, and a time-reaction temperature curve is plotted.

[0060] Before starting the furnace, turn on the delivery pump, close the circulation control valve, and open the cooling control valve to lower the temperature of VOCl3 in the atomization tower to -10 ℃. Once the required temperature is reached, turn off the delivery pump and the cooling control valve. During this period, introduce nitrogen gas into the atomization tower to maintain a pressure difference of 0.15 MPa between the atomization tower and the chlorination furnace.

[0061] After the furnace was started, the overall temperature inside the furnace began to rise, and the temperature in the upper part of the reaction section rose rapidly. The experiment was started about 5 minutes before the temperature of 001 reached 650 ℃. The temperature measurement point 001 showed an overheating situation. At this time, the delivery pump and circulation control valve were opened, and the air inlet control valve on the 01 atomized gas delivery pipe was gradually opened. The opening of the air inlet control valves on the other 02, 03 and 04 atomized gas delivery pipes remained unchanged. The experimental time and valve opening are compared in Table 4 below.

[0062] In order to reduce the reaction temperature as soon as possible, the opening of the atomizing gas pipe 01 was increased to 100% after 12 minutes. After increasing the opening, the temperature in the middle and upper parts was basically stable, but the temperature of the material at the top dropped rapidly. When the reaction proceeded for 30 minutes, the temperature of the material at the top dropped to about 550 ℃. Although the downward trend slowed down, this temperature was close to the lower limit of the process. The temperature difference in the furnace was large and could not meet the requirements of the chlorination process.

[0063] After the experiment, the chlorination furnace was fed normally, and the liquid level in the tower decreased. The distance from the lowest atomizing gas delivery pipe was ≥600 mm. Vanadium oxychloride was then added to the tower through the storage tank to restore the liquid level. Simultaneously, the delivery pump was started, and the cooling control valve was opened, maintaining a 20% valve opening. Once the temperature of vanadium oxychloride in the tower was ≤0 ℃, the delivery pump was restarted, and the cooling control valve was closed.

[0064] Table 4 Intake Control Valve Opening

[0065] Experimental period Atomizing gas delivery pipe 01 Atomizing gas delivery pipe 02 Atomizing gas delivery pipe 03 Atomizing gas delivery pipe 04 0~5 min 0% 0% 0% 0% 5~12 min 75% 0% 0% 0% 13~32 min 100% 0% 0% 0%

[0066] Example 5

[0067] This embodiment uses four atomizing gas delivery pipes to control the temperature of different parts of the reaction section. The chlorination furnace used in the experiment has an inner diameter of 1 m, an atomizing tower diameter of 0.5 m, and a reaction section height of 5 m. It has top feeding, and four sets of atomizing gas delivery pipes are installed on the side of the reaction section from top to bottom, named 01, 02, 03, and 04 respectively. Four temperature measuring points are set inside the furnace from top to bottom, namely 001, 002, 003, and 004. The diameter of the atomizing gas delivery pipes is 50 mm, with the outer part made of stainless steel and the inner part made of corundum, connected by flanges. The top of the inner part of the furnace is hemispherical, with evenly distributed nozzles of 7.5 mm diameter. The vertical distance between the atomizing gas delivery pipes is 1.5 m, and their positions are aligned with the cross-sectional diameter of the chlorination furnace. DCS data during the reaction process is exported, with one point exported every 5 seconds, and a time-reaction temperature curve is plotted.

[0068] Before starting the furnace, turn on the delivery pump, close the circulation control valve, and open the cooling control valve to lower the temperature of VOCl3 in the atomization tower to -10 ℃. Once the required temperature is reached, turn off the delivery pump and the cooling control valve. During this period, introduce nitrogen gas into the atomization tower to maintain a pressure difference of 0.15 MPa between the atomization tower and the chlorination furnace.

[0069] After the furnace is started, the overall temperature inside the furnace begins to rise, and the temperature in the upper part of the reaction section rises rapidly. The experiment is started about 5 minutes before the temperature of 001 reaches 650 ℃. At this time, the delivery pump and circulation control valve are opened, and the air inlet control valve on the 04 atomizing gas delivery pipe is gradually opened to 100%. The air inlet control valves of the other 01, 02 and 03 atomizing gas delivery pipes are in the closed state. The experimental time and valve opening are compared in Table 5 below.

[0070] After about 15 minutes of the experiment, the bottom reaction temperature dropped to about 550 ℃ and showed a downward trend. However, under this opening condition, the temperature in the middle and upper parts was still rising, making it impossible to control the temperature inside the furnace. The temperature distribution inside the furnace was uneven, with large temperature differences, which could not meet the process requirements. Therefore, the experiment was stopped. The opening of the valves of the 01, 02, 03, and 04 atomizing gas delivery pipes was adjusted to regulate the temperature of each part inside the furnace, and the temperature fluctuation of each part of the reaction section was controlled within 10 ℃.

[0071] After the experiment, the chlorination furnace was fed normally, and the liquid level in the tower decreased. The distance from the lowest atomizing gas delivery pipe was ≥600 mm. Vanadium oxychloride was then added to the tower through the storage tank to restore the liquid level. Simultaneously, the delivery pump was started, and the cooling control valve was opened, maintaining a 20% valve opening. Once the temperature of vanadium oxychloride in the tower was ≤0 ℃, the delivery pump was restarted, and the cooling control valve was closed.

[0072] Table 5 Intake Control Valve Opening

[0073] Experimental period Atomizing gas delivery pipe 01 Atomizing gas delivery pipe 02 Atomizing gas delivery pipe 03 Atomizing gas delivery pipe 04 0~5 min 0% 0% 0% 0% 5~15 min 0% 0% 0% 100% 16~32 min 40% 30% 30% 20%

[0074] A comparison of Examples 1 and 2 reveals that top spraying alone cannot effectively cool the lower part of the reaction section, resulting in a large temperature difference within the furnace. Similarly, a comparison of Examples 1 and 3 also shows that during the reaction process, top spraying or bottom spraying alone cannot effectively control the temperature in the middle of the reaction section, leading to a large temperature difference within the furnace, which is detrimental to the control of the chlorination reaction.

[0075] After comparison, it was found that the embodiments provided by the present invention have the following positive effects compared with the prior art:

[0076] This invention connects the furnace temperature control system to different areas of the chlorination furnace reaction section from the side. A certain amount of liquid chloride droplets are sprayed into the furnace through an atomizing gas delivery pipe. This method minimizes thermal shock to the furnace and ensures more uniform heat transfer. Top and bottom spraying can lead to excessively low temperatures at the top or bottom of the furnace, making it impossible to accurately control the reaction temperature of different reaction sections in the chlorination furnace, thus affecting fluidization and the chlorination reaction. Side air intake can directly cool the overheated areas of the reaction section, avoiding the situation where cooling the core area leads to excessively low temperatures in other parts of the furnace. At the same time, side air intake can also improve the fluidization uniformity in the furnace, avoiding channeling or dead zones caused by excessively large local bubbles. Through the method provided by this invention, the temperature of each part of the furnace can be precisely controlled, the fluidization state can be improved, and some raw materials with high iron, calcium, and magnesium content can also be used in the chlorination process, broadening the application range of the chlorination process.

[0077] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling furnace temperature in a fluidized bed chlorination reaction, characterized in that, The furnace temperature is controlled by injecting liquid chloride droplets into different areas of the reaction section from the side through a furnace temperature control system connected to the chlorination furnace.

2. The furnace temperature control method for a fluidized bed chlorination reaction according to claim 1, characterized in that: The furnace temperature control system includes an atomizing tower (3), a delivery pump (9), an atomizing nozzle (6), a gas delivery pipeline (1, 5), and a liquid circulation pipeline (4, 10). The atomizing tower is equipped with a pressure sensor and a temperature sensor, and a liquid level sensor is installed at the bottom. The atomizing tower (3) is connected to the chlorination furnace through an atomizing gas delivery pipe (1).

3. The furnace temperature control method for a fluidized bed chlorination reaction according to claim 2, characterized in that: The gas delivery pipeline system (1, 5) includes a nitrogen inlet pipe (5) and an atomizing gas delivery pipe (1). Nitrogen is continuously introduced into the nitrogen inlet pipe to ensure that the pressure inside the atomizing tower is maintained at a certain level and is higher than the pressure inside the furnace, with a pressure difference of 0.1 ~ 0.15 MPa.

4. The furnace temperature control method for a fluidized bed chlorination reaction according to claim 2, characterized in that: The bottom of the atomizing tower (3) is connected to the atomizing nozzle inside the tower via a delivery pump (9), a circulation control valve (12), and a liquid circulation pipeline (4, 10). After passing through the atomizing nozzle (6), the chloride at the bottom of the tower forms atomized droplets inside the tower. The nitrogen gas introduced into the nitrogen gas inlet pipe mixes with the atomized droplets and then enters the furnace through the atomizing gas delivery pipe (1) and the control valve (2). The horizontal atomizing nozzle on the side wall of the atomizing tower is at the same height as the atomizing gas delivery pipe.

5. The furnace temperature control method for a fluidized bed chlorination reaction according to claim 4, characterized in that: The delivery pump (9) is connected to the chiller through the cooling control valve (7) and the cooling circulation pipe (8). The liquid cooled by the chiller enters the atomizing tower (3) through the liquid inlet (11). The temperature of the liquid chloride is adjusted to ≤ 0 ℃ with the temperature sensor in the atomizing tower. The liquid inlet (11) is connected to the storage tank and can be used with the liquid level sensor in the tower to control the liquid level of the liquid chloride at the bottom of the atomizing tower. The distance between the liquid level in the tower and the lowest position atomizing nozzle is ≥ 600 mm.

6. The furnace temperature control method for a fluidized bed chlorination reaction according to claim 4, characterized in that: The diameter of the atomizing gas delivery pipe furnace is 50 ~ 100 mm. The outer part of the pipeline is made of stainless steel, while the inside of the furnace is made of corundum. The two parts are connected by flanges. The top of the inner part of the furnace is hemispherical, with spray holes evenly distributed on the surface. The diameter of the spray holes is 5 ~ 10 mm. The vertical distance of the atomizing gas delivery pipe is 1 ~ 1.5 m, and its position is on the same straight line as the cross-sectional diameter of the chlorination furnace.

7. A furnace temperature control method for a fluidized bed chlorination reaction according to claims 1-5, characterized in that: All valves in the device are pneumatic regulating valves. All valves, sensors, and delivery pumps in the device are electrically connected to the DCS control system. After the furnace is started, when the temperature exceeds the process requirements, the delivery pump is turned on, and nitrogen gas delivers the atomized chloride into the furnace. According to the reaction temperature rise in different parts of the furnace, the opening of each gas inlet valve is adjusted to control the amount of atomized gas entering the furnace at different locations.

8. A method for controlling furnace temperature in a fluidized bed chlorination reaction, characterized in that, The furnace temperature control method for fluidized bed chlorination reaction as described in any one of claims 1 to 7 is used to control the chlorination reaction temperature. The specific control steps are as follows: Step 1: Before starting the chlorination furnace, replenish the liquid level in the tower through the liquid inlet (11), turn on the transfer pump (9), open the cooling control valve (8) to cool the liquid in the tower, and keep the liquid temperature in the atomization tower ≤ 0 ℃. Step 2: When starting the chlorination furnace, maintain a pressure difference of 0.1 ~ 0.15 MPa between the atomizing tower and the furnace through the nitrogen inlet pipe (5); Step 3: After the reaction begins, turn on the delivery pump and open the circulation control valve (12). The liquid chloride passes through the atomizing nozzle to form atomized gas, which mixes with nitrogen to form high-pressure atomized gas (composed of high-pressure nitrogen and atomized liquid chloride). The DCS control system detects the temperature at different locations in the furnace. When the furnace needs to be cooled, the atomized gas can be quickly injected into the furnace through the atomized gas inlet pipe. The liquid chloride evaporates and absorbs heat in the furnace, reducing the furnace temperature. According to the temperature at different locations in the furnace, control the opening of the gas inlet control valve. If the reaction temperature at a certain location in the reaction section exceeds the optimal control temperature range of the process, the valve opening on the atomized gas inlet pipe at the corresponding location needs to be increased to increase the gas inlet volume and reduce the reaction temperature. If the reaction temperature at a certain location in the reaction section is lower than the optimal control temperature range of the process, the valve opening on the atomized gas inlet pipe at the corresponding location needs to be reduced or even closed to reduce the gas inlet volume at that reaction location.

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