A long-term operation method for effectively increasing the feeding amount of molten salt chlorination furnace in the later stage of operation

Abstract

A long-term operation method that effectively increases the amount of material fed into a molten salt chlorination furnace in the later stage of operation. With the operation of the molten salt chlorination system, the inner wall of the chlorine gas pipeline in front of the furnace of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure in the buffer tank gradually increases. When the pressure in the buffer tank affects the stable operation of the molten salt chlorination system, the molten salt chlorination furnace performs a salt return operation; ensure that the molten salt in the molten salt chlorination furnace is completely solidified after returning to the chlorine pipe outside the molten salt chlorination furnace, clean or replace the chlorine gas pipeline in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline in front of the furnace, and restart the furnace production. The advantages are: the process is simple, the chlorine gas pipeline in front of the furnace that is blocked in the later stage of the chlorination furnace operation can be cleared online, and the docking pressure between the chlorination furnace and the oxidation can be reduced, thereby achieving the purpose of increasing the amount of material fed into the chlorination furnace, effectively avoiding the situation where the amount of material fed is reduced due to the increase in docking pressure, greatly increasing the output of crude titanium tetrachloride and titanium dioxide in the chlorination furnace, and ensuring the long-term operation of the molten salt chlorination.

Description

Technical Field

[0001] The invention relates to a long-period operation method for effectively increasing the feeding amount of a molten salt chlorination furnace in the later stage of operation. Background Art

[0002] Molten salt chlorination refers to the process in which high-titanium slag is chlorinated into chlorides by chlorine gas in the presence of reducing agent carbon in a molten salt medium. In the titanium dioxide production process, the source of chlorine gas in the molten salt chlorination production process is mainly the tail gas generated by the oxidation process (the Cl2 content in the oxidation tail gas accounts for about 70%-76%), supplemented by pure chlorine as a production raw material.

[0003] In the molten salt chlorination production process, the molten salt chlorination furnace receives the tail gas from the oxidation process to chlorinate the high-titanium slag with molten salt. In the later period of continuous operation of the molten salt chlorination furnace, the docking pressure often increases, affecting the safe operation of the oxidation furnace. In order to ensure that the oxidation furnace continues to dock with the chlorination furnace and operate stably, the oxidation furnace feed amount needs to be reduced, which will affect the production capacity of the oxidation furnace and the molten salt chlorination furnace, and reduce the output of crude titanium tetrachloride and titanium dioxide. After long-term exploration by technical personnel, the reasons for the increase in docking pressure are analyzed: mainly because the impurities in the tail gas of the oxidation process will inevitably enter the chlorine gas pipeline in front of the furnace of the molten salt chlorination furnace, and gradually adhere and scar on the inner wall of the pipeline. Long-term operation causes the effective cross-sectional area of ​​the chlorine gas pipeline in front of the furnace to decrease, and the pipeline pressure increases; and the blockage state of the chlorine gas pipeline in front of the furnace becomes more and more serious with the extension of the production cycle of the molten salt chlorination furnace. In order to ensure the stable operation of the entire system, the feed amount is reduced, resulting in lower and lower outputs of the oxidation process and the molten salt chlorination process.

[0004] The blockage of the chlorine gas pipeline in front of the furnace is difficult to clean. If the chlorine gas pipeline in front of the furnace is directly disassembled and cleaned in a conventional manner, the high-temperature molten salt in the furnace will be ejected through the barrel needle installed at the chlorine gas inlet of the molten salt chlorination furnace, resulting in serious safety and environmental accidents. Therefore, the molten salt chlorination furnace cannot disassemble and clean the blocked chlorine gas pipeline in front of the furnace during production or shutdown and insulation. It is necessary to ensure that chlorine gas or air with a certain pressure always enters the molten salt chlorination furnace through the chlorine gas pipeline in front of the furnace to prevent the molten salt from returning; and once the chlorine gas or air pressure entering the molten salt chlorination furnace is too low, the high-temperature molten salt in the molten salt chlorination furnace will quickly return to the chlorine gas pipeline in front of the furnace through the barrel needle installed at the chlorine gas inlet of the molten salt chlorination furnace, which will cause the barrel needle to be blocked by solidified molten salt and forced to stop using. After the barrel needle is stopped, chlorine gas cannot enter the molten salt chlorination furnace, and the furnace can only be shut down for maintenance, affecting the operation cycle. Therefore, there is currently no effective solution to the problem of increased docking pressure and reduced production due to blockage of the chlorine gas pipeline in front of the molten salt chlorination furnace in the later stage of operation. The molten salt chlorination furnace can only replace the pure chlorine pipeline, shut down or go offline for maintenance, and the oxidation system is forced to shut down, which seriously affects the production of titanium dioxide. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a long-term operation method for effectively improving the feed amount of a molten salt chlorination furnace in the later stage of operation. The chlorine gas pipeline in front of the furnace that is blocked in the later stage of operation of the chlorination furnace can be cleared online, and the docking pressure between the chlorination furnace and the oxidation furnace can be reduced, thereby achieving the purpose of increasing the feed amount of the chlorination furnace, effectively avoiding the situation where the feed amount is reduced due to the increase in the docking pressure, greatly increasing the output of crude titanium tetrachloride and titanium dioxide in the chlorination furnace, ensuring the long-term operation of the molten salt chlorination, and creating good economic benefits.

[0006] The technical solution of the present invention:

[0007] A chlorine system in front of a molten salt chlorination furnace comprises a chlorine pipe, which is special in that: cooling water nozzles are installed on both sides of the chlorine pipe; the chlorine inlet of the chlorine pipe is connected to a chlorine pipeline in front of the furnace and a barrel needle sealing pipe through a tee, and a barrel needle is slidably installed at the outlet of the barrel needle sealing pipe. When the barrel needle is driven in, the barrel needle passes through the tee and the chlorine pipe in sequence through the barrel needle sealing pipe and extends into the molten salt chlorination furnace. When the barrel needle is pulled out, the insertion end of the barrel needle is located at the connection end of the tee and the barrel needle sealing pipe; the chlorine pipeline in front of the furnace The air inlet end is connected to an air buffer tank and a chlorine buffer tank through an air pipeline and a chlorine pipeline respectively. A pressure transmitter is installed on the chlorine pipeline in front of the furnace, a chlorine pressure regulating valve is installed on the chlorine pipeline, and an air pressure regulating valve is installed on the air pipeline; an air pressure regulating main valve is installed on the air inlet pipe of the air buffer tank, an oxidation-connected chlorine pipeline is connected to the air inlet of the chlorine buffer tank, a chlorine supply valve is provided on the oxidation-connected chlorine pipeline, and a pressure relief valve is installed on the top of the chlorine buffer tank.

[0008] Furthermore, an infrared thermometer is provided at the tee to measure the internal temperature of the tee.

[0009] Furthermore, a first pressure gauge is provided on the pipeline between the air buffer tank and the air pressure regulating main valve, and a second pressure gauge is provided on the pipeline between the chlorine buffer tank and the chlorine supply valve.

[0010] Furthermore, the chlorine buffer tank has a chlorine buffer tank pressure gauge.

[0011] Furthermore, the chlorine gas port of the oxidation-connected chlorine gas pipeline is connected to the tail gas emission pipe of the titanium tetrachloride oxidation furnace.

[0012] A long-term operation method for effectively increasing the feeding amount of a molten salt chlorination furnace in the later stage of operation, the specific steps of which are:

[0013] (1) Operation of molten salt chlorination system

[0014] The chlorine pipe of the chlorine gas system in front of the molten salt chlorination furnace is installed at the chlorine inlet of the molten salt chlorination furnace to form a molten salt chlorination system. The molten salt chlorination system is started and operated, the air pressure regulating valve is closed, the chlorine gas supply valve, the chlorine gas pressure regulating valve and the air pressure regulating main valve are opened, and chlorine is introduced into the molten salt chlorination furnace through the chlorine gas system in front of the molten salt chlorination furnace to carry out the molten salt chlorination reaction; as the molten salt chlorination system is operated, the inner wall of the chlorine gas pipeline in front of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure of the chlorine gas buffer tank gradually increases. When the pressure in the buffer tank affects the stable operation of the molten salt chlorination system, the molten salt chlorination furnace performs the salt return operation; (2) Preparation before the salt return operation

[0015] Adjust the main air pressure regulating valve to maintain the pressure of the air buffer tank at 0.3Mpa-0.5Mpa, close the chlorine pressure regulating valve, and open the air pressure regulating valve at the same time. After the chlorine pressure regulating valve is completely closed, close the chlorine gas supply valve and insert the barrel needle into the chlorine pipe to stop chlorine and cut off the wind for insulation. Adjust the air pressure regulating valve to maintain the air pressure entering the furnace at 0.12Mpa±0.02Mpa, open the cooling water nozzle, cool the chlorine pipe outside the molten salt chlorination furnace for 30 minutes, and then perform the salt return operation;

[0016] (3) Salt return operation

[0017] A first thermocouple is arranged at a position 1 / 10 of the height of the molten salt chlorination furnace body from the bottom of the molten salt chlorination furnace body, and a second thermocouple is arranged at a position 1 / 3 of the height of the molten salt chlorination furnace body from the bottom of the molten salt chlorination furnace body; the temperature of the No. 1 measuring point of the molten salt chlorination furnace measured by the first thermocouple is between 580°C and 650°C to prevent the molten salt from solidifying; the temperature of the No. 2 measuring point of the molten salt chlorination furnace measured by the second thermocouple is between 790°C and 880°C to reduce fluidity, perform salt return operation, and maintain this temperature during the salt return operation;

[0018] By gradually closing the air pressure regulating valve, the air pressure entering the furnace is gradually reduced from 0.10Mpa-0.14Mpa to 0.06MPa-0.07MPa, and the pressure is stabilized for 2 minutes every time the pressure is reduced by 0.01Mpa; when the pressure is reduced to 0.06Mpa-0.07Mpa, the chlorine system in front of the molten salt chlorination furnace and the pressure in the molten salt chlorination furnace tend to be in a balanced state, and the pressure is continued to be reduced. The pressure is stabilized for 4 minutes every time the pressure is reduced by 0.01Mpa, to ensure that the molten salt in the molten salt chlorination furnace is returned to the chlorine pipe outside the molten salt chlorination furnace and is completely solidified until the air pressure regulating valve is completely closed; at this time, the pressure relief valve on the top of the chlorine buffer tank is opened first, and then the chlorine pressure regulating valve is opened to relieve the pressure of the chlorine gas pipeline in front of the furnace, and the pressure of the chlorine gas pipeline in front of the furnace is reduced to 0Mpa, and it is stabilized for 10 minutes to 15 minutes to complete the salt return operation;

[0019] (4) Clean or replace the chlorine gas pipeline in front of the furnace

[0020] Remove the chlorine gas pipeline in front of the furnace, and then blind the tee with a blind plate to seal the chlorine gas pipe; clean or replace the chlorine gas pipeline in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline in front of the furnace; after the chlorine gas pipeline is reinstalled, pull out the barrel needle to start the furnace production; before pulling out the barrel needle, close the pressure relief valve on the top of the chlorine buffer tank, open the chlorine gas supply valve, and send chlorine to the chlorine buffer tank. The pressure of the chlorine buffer tank is maintained at 0.13MPa-0.16Mpa, open the air pressure regulating valve to maintain the furnace air pressure at 0.10Mpa-0.14Mpa, pull the barrel needle out of the chlorine gas pipe to the flange of the tee close to the barrel needle sealing tube, the high-temperature molten salt in the furnace will melt the previously solidified molten salt, after the barrel needle is pulled out, close the air pressure regulating valve, and open the chlorine pressure regulating valve at the same time, and the furnace production will be restarted after the switch is completed.

[0021] Furthermore, when the molten salt chlorination system is started in step (1), the pressure in the chlorine buffer tank is maintained at 0.13MPa-0.16MPa; when the pressure in the chlorine buffer tank reaches 0.26MPa-0.3MPa, the stable operation of the molten salt chlorination system is affected, and the molten salt chlorination furnace needs to perform salt return operation.

[0022] Furthermore, when the molten salt chlorination system is in operation, the height of the molten salt liquid level in the molten salt chlorination furnace from the furnace bottom is maintained at 4.8m-5.2m.

[0023] Furthermore, in step (3), when the air pressure regulating valve is gradually closed or the pressure of the chlorine gas pipeline in front of the tube furnace is relieved and the pressure of the chlorine gas pipeline in front of the furnace is reduced to 0 MPa, the temperature value displayed by the infrared thermometer at the three-way position is observed in real time. If the temperature at the measuring point rises sharply, the air pressure regulating valve is immediately opened to supply air to prevent molten salt from entering the chlorine gas pipeline in front of the furnace.

[0024] Furthermore, the cooling water temperature of the cooling water nozzle is ≤25°C.

[0025] Beneficial effects of the present invention:

[0026] By gradually reducing the air pressure of the furnace inlet pipe, during the process of reducing the air pressure of the chlorine pipe inlet pipe, the designated part of the chlorine pipe device in front of the furnace is cooled by cooling water, so that the molten salt returned from the furnace is cooled and solidified in the chlorine pipe, preventing the molten salt in the furnace from overflowing (the returned molten salt is finally cooled and solidified at the cooling water cooling position, and the high-temperature molten salt in the furnace can be melted again during the production of the barrel needle, which will not cause other effects, and avoid entering the chlorine pipe in front of the furnace and solidifying to disable the barrel needle). When the pressure of the chlorine pipe is reduced to different pressure values, a certain cooling time must be ensured. The molten salt that is quickly solidified by cooling water plays a role in preventing the high-temperature molten salt in the furnace from further returning. After the final molten salt is cooled and solidified for a certain period of time, the conditions for online disassembly and cleaning of the chlorine pipe are met, the upper short-circuit of the chlorine pipe tee is disassembled, and the blind plate is sealed. After the online dredging of the chlorine pipe in front of the furnace, the pressure of the connection with the titanium tetrachloride oxidation furnace returns to normal, and the feeding amount of the molten salt chlorination furnace returns to normal. After cleaning, immediately reinstall and pull out the barrel needle to start the furnace production. After the chlorine gas pipeline in front of the furnace is unblocked, the problem of high docking pressure in the late operation of the molten salt chlorination furnace is completely solved. At this time, the molten salt chlorination furnace can be fully loaded and produced, and the chlorine gas pipeline in front of the furnace can be unblocked and cleaned online, so that the chlorination furnace can be fully loaded and operated within four to eight months in the late production period. The output of crude titanium tetrachloride and titanium dioxide will be greatly improved, ensuring the long-term operation of molten salt chlorination. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the front system of the molten salt chlorination furnace in the technical solution of the present invention;

[0028] Figure 2 yes Figure 1 Enlarged view of part A.

[0029] In the figure: 1-molten salt chlorination furnace, 2-chlorine pipe, 3-tee, 4-barrel needle sealing tube, 5-barrel needle, 6-infrared thermometer, 7-chlorine pipeline in front of the furnace, 8-pressure transmitter, 9-cooling water nozzle, 10-air pressure regulating valve, 11-chlorine pressure regulating valve, 12-air buffer tank, 13-air pressure regulating main valve, 14-chlorine buffer tank, 15-oxidation docking chlorine pipeline, 16-chlorine supply valve, 17-pressure relief valve, 18-first thermocouple, 19-second thermocouple, 20-first pressure gauge, 21-second pressure gauge. DETAILED DESCRIPTION

[0030] Embodiments will be described below with reference to the accompanying drawings.

[0031] A total of 4 sets of chlorine gas pipelines in front of the furnace are installed on the molten salt chlorination furnace of the present invention, and the following figure shows one of the sets.

[0032] Example 1

[0033] (1) Operation of molten salt chlorination system

[0034] like Figure 1-2 As shown, the chlorine system in front of the molten salt chlorination furnace includes a chlorine pipe 2, and cooling water nozzles 9 are installed on both sides of the chlorine pipe 2; the chlorine inlet of the chlorine pipe 2 is connected to the front chlorine pipeline 7 and the barrel needle sealing pipe 4 through a tee 3, respectively, the barrel needle sealing pipe 4 is connected to the tee 3 through a flange, the tee 3 is connected to the front chlorine pipeline 7 through a flange, and a barrel needle 5 is slidably installed at the outlet of the barrel needle sealing pipe 4, the barrel needle 5 and the barrel needle sealing pipe 4 are a packing sealing structure, when the barrel needle 5 is driven in, the barrel needle 5 passes through the tee 3 and the chlorine pipe 2 in sequence through the barrel needle sealing pipe 4 and extends into the molten salt chlorination furnace 1, and when the barrel needle 5 is pulled out, the barrel needle 5 The insertion end is located at the connection flange of the tee 3 and the barrel needle sealing tube 4; an infrared thermometer 6 is arranged at the tee 3 to measure the internal temperature of the tee 3; the air inlet end of the chlorine gas pipeline 7 in front of the furnace is connected to the air buffer tank 12 and the chlorine gas buffer tank 14 through the air pipeline and the chlorine gas pipeline respectively, and the chlorine gas buffer tank 14 has a chlorine gas buffer tank pressure gauge and a pressure relief valve 17 installed on the top; a pressure transmitter 8 is installed on the chlorine gas pipeline 7 in front of the furnace, a chlorine gas pressure regulating valve 11 is installed on the chlorine gas pipeline, and an air pressure regulating valve 10 is installed on the air pipeline; an air pressure regulating valve 12 is installed on the air inlet pipe of the air buffer tank 12 A chlorine gas supply valve 16 is provided on the chlorine gas supply pipe 16; a chlorine gas supply pipe 2 of the chlorine gas supply pipe 11 is installed at the chlorine gas supply pipe 12 of the molten salt chlorination furnace, and the chlorine gas supply pipe 2 is installed at the chlorine gas supply pipe 13 of the molten salt chlorination furnace. The chlorine gas supply pipe 2 of the chlorine gas supply pipe 11 is installed at the chlorine gas supply pipe 14 of the molten salt chlorination furnace, and the chlorine gas supply pipe 2 is installed at the chlorine gas supply pipe 15 of the molten salt chlorination furnace, and the molten salt chlorination system is assembled. When the molten salt chlorination system is started, the air pressure regulating valve 10 is closed, the chlorine gas supply valve 16, the chlorine gas pressure regulating valve 11 and the air pressure regulating main valve 13 are opened, and the chlorine gas supply valve 16, the chlorine gas pressure regulating valve 11 and the air pressure regulating main valve 13 are opened. Chlorine is introduced into the chlorination furnace 1 to carry out the molten salt chlorination reaction. At this time, the pressure in the chlorine buffer tank 14 is maintained at 0.13MPa-0.14MPa. When the molten salt chlorination system is in operation, the height of the molten salt liquid level in the molten salt chlorination furnace 1 from the furnace bottom is maintained at 5m±0.2m; with the operation of the molten salt chlorination system, the inner wall of the chlorine gas pipeline 7 of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure of the chlorine buffer tank 14 gradually increases. After eight months of continuous operation, the pressure of the chlorine buffer tank 14 reaches 0.26MPa, which has had a certain impact on the stable operation of the molten salt chlorination system, and the molten salt chlorination furnace 1 performs salt return operation;

[0035] (2) Preparation before salt return operation

[0036] Regulate the main air pressure regulating valve 13 to maintain the pressure of the air buffer tank 12 at 0.4Mpa±0.1Mpa, close the chlorine pressure regulating valve 11, and open the air pressure regulating valve 10 at the same time. After the chlorine pressure regulating valve 11 is completely closed, close the chlorine gas supply valve 16 and insert the barrel needle 5 into the chlorine pipe 2 to stop chlorine and cut off the wind for insulation. Regulate the air pressure regulating valve 10 to maintain the furnace air pressure (displayed by the pressure transmitter 8) at 0.12Mpa±0.02Mpa, open the cooling water nozzle 9 (the cooling water temperature of the cooling water nozzle 9 is 25°C), cool the chlorine pipe 2 located outside the molten salt chlorination furnace 1 for 30 minutes, and then perform the salt return operation;

[0037] (3) Salt return operation

[0038] A first thermocouple 18 is arranged at a position 1 / 10 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1, and a second thermocouple 19 is arranged at a position 1 / 3 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1; the temperature measuring point No. 1 of the molten salt chlorination furnace 1 measured by the first thermocouple 18 is 580° C.-600° C. to prevent the molten salt from solidifying; the temperature measuring point No. 2 of the molten salt chlorination furnace 1 measured by the second thermocouple 19 is 790° C.-810° C. to reduce the fluidity of the molten salt, perform the salt return operation, and maintain this temperature during the salt return operation;

[0039] By gradually closing the air pressure regulating valve 10, the inlet air pressure (displayed by the pressure transmitter 8) is gradually reduced from 0.1Mpa to 0.06MPa. The height of the molten salt liquid level from the furnace bottom in the molten salt chlorination furnace 1 is monitored to be 4.8m. The pressure is stabilized for 2 minutes for every 0.01Mpa decrease in pressure. When the pressure drops to 0.06Mpa, the pressure in the chlorine system in front of the molten salt chlorination furnace and the pressure in the molten salt chlorination furnace 1 tend to be in a balanced state. The pressure is further reduced. The pressure is stabilized for 4 minutes for every 0.01Mpa decrease in pressure. 1, the molten salt in the chlorine pipe 2 is returned to the outside of the molten salt chlorination furnace 1 and completely solidified until the air pressure regulating valve 10 is completely closed; at this time, the pressure relief valve 17 on the top of the chlorine buffer tank 14 is opened first, and then the chlorine pressure regulating valve 11 is opened to relieve the pressure of the chlorine pipeline 7 in front of the furnace, and the pressure of the chlorine pipeline 7 in front of the furnace (the pressure transmitter 8 shows) is reduced to 0Mpa and stabilized for 10 minutes. At this time, the molten salt returns to the flange of the tee 3 close to one side of the molten salt chlorination furnace 1 (the flange connected to the chlorine pipe 2) and is completely solidified, completing the salt return operation;

[0040] When gradually closing the air pressure regulating valve 10 or relieving the pressure of the chlorine gas pipeline 7 in front of the tube furnace and the pressure relief of the chlorine gas pipeline 7 in front of the furnace drops to 0Mpa, observe the temperature value displayed by the infrared thermometer 6 at the three-way 3 position in real time. If the temperature at the temperature measuring point rises sharply, immediately open the air pressure regulating valve 10 to supply air to prevent molten salt from entering the chlorine gas pipeline 7 in front of the furnace;

[0041] (4) Clean or replace the chlorine gas pipeline in front of the furnace

[0042] Remove the chlorine gas pipeline 7 in front of the furnace, and then blind the tee 3 with a blind plate to seal the chlorine gas pipe 2; clean or replace the chlorine gas pipeline 7 in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline 7 in front of the furnace; after the chlorine gas pipeline is reinstalled, pull out the barrel needle 5 to start the furnace production; before pulling out the barrel needle 5, close the pressure relief valve 17 on the top of the chlorine buffer tank 14, open the chlorine gas supply valve 16, and send chlorine to the chlorine buffer tank 14. The pressure of the chlorine buffer tank 14 is maintained at 0.13MPa; open the air pressure regulating valve 10 to maintain the furnace air pressure at 0.1Mpa, pull out the barrel needle 5 from the chlorine gas pipe 2 to the flange of the tee 3 close to the barrel needle sealing tube 4, and the high-temperature molten salt in the furnace will melt the previously solidified molten salt. After the barrel needle 5 is pulled out, close the air pressure regulating valve 10, and open the chlorine pressure regulating valve 11 at the same time. After the switch is completed, the furnace is restarted and the operation continues for eight months. The continuous operation cycle reaches sixteen months, and the furnace is shut down and taken offline for maintenance.

[0043] Example 2

[0044] (1) Operation of molten salt chlorination system

[0045] like Figure 1-2As shown, the chlorine system in front of the molten salt chlorination furnace includes a chlorine pipe 2, and cooling water nozzles 9 are installed on both sides of the chlorine pipe 2; the chlorine inlet of the chlorine pipe 2 is connected to the front chlorine pipeline 7 and the barrel needle sealing pipe 4 through a tee 3, respectively, the barrel needle sealing pipe 4 is connected to the tee 3 through a flange, the tee 3 is connected to the front chlorine pipeline 7 through a flange, and a barrel needle 5 is slidably installed at the outlet of the barrel needle sealing pipe 4, the barrel needle 5 and the barrel needle sealing pipe 4 are a packing sealing structure, when the barrel needle 5 is driven in, the barrel needle 5 passes through the tee 3 and the chlorine pipe 2 in sequence through the barrel needle sealing pipe 4 and extends into the molten salt chlorination furnace 1, and when the barrel needle 5 is pulled out, the barrel needle 5 The insertion end is located at the connection flange of the tee 3 and the barrel needle sealing tube 4; an infrared thermometer 6 is arranged at the tee 3 to measure the internal temperature of the tee 3; the air inlet end of the chlorine gas pipeline 7 in front of the furnace is connected to the air buffer tank 12 and the chlorine gas buffer tank 14 through the air pipeline and the chlorine gas pipeline respectively, and the chlorine gas buffer tank 14 has a chlorine gas buffer tank pressure gauge and a pressure relief valve 17 installed on the top; a pressure transmitter 8 is installed on the chlorine gas pipeline 7 in front of the furnace, a chlorine gas pressure regulating valve 11 is installed on the chlorine gas pipeline, and an air pressure regulating valve 10 is installed on the air pipeline; an air pressure regulating valve 12 is installed on the air inlet pipe of the air buffer tank 12 A chlorine gas supply valve 16 is provided on the chlorine gas supply pipe 16; a chlorine gas supply pipe 2 of the chlorine gas supply pipe 11 is installed at the chlorine gas supply pipe 12 of the molten salt chlorination furnace, and the chlorine gas supply pipe 2 is installed at the chlorine gas supply pipe 13 of the molten salt chlorination furnace. The chlorine gas supply pipe 2 of the chlorine gas supply pipe 11 is installed at the chlorine gas supply pipe 14 of the molten salt chlorination furnace, and the chlorine gas supply pipe 2 is installed at the chlorine gas supply pipe 15 of the molten salt chlorination furnace, and the molten salt chlorination system is assembled. When the molten salt chlorination system is started, the air pressure regulating valve 10 is closed, the chlorine gas supply valve 16, the chlorine gas pressure regulating valve 11 and the air pressure regulating main valve 13 are opened, and the chlorine gas supply valve 16, the chlorine gas pressure regulating valve 11 and the air pressure regulating main valve 13 are opened. Chlorine is introduced into the chlorination furnace 1 to carry out the molten salt chlorination reaction. At this time, the pressure in the chlorine buffer tank 14 is maintained at 0.14MPa-0.15MPa. When the molten salt chlorination system is in operation, the height of the molten salt liquid level in the molten salt chlorination furnace 1 from the furnace bottom is maintained at 5m±0.2m; with the operation of the molten salt chlorination system, the inner wall of the chlorine pipeline 7 of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure of the chlorine buffer tank 14 gradually increases. After ten months of continuous operation, the pressure of the chlorine buffer tank 14 reaches 0.28MPa, which has had a certain impact on the stable operation of the molten salt chlorination system, and the molten salt chlorination furnace 1 performs salt return operation;

[0046] (2) Preparation before salt return operation

[0047] Regulate the main air pressure regulating valve 13 to maintain the pressure of the air buffer tank 12 at 0.4Mpa±0.1Mpa, close the chlorine pressure regulating valve 11, and open the air pressure regulating valve 10 at the same time. After the chlorine pressure regulating valve 11 is completely closed, close the chlorine gas supply valve 16 and insert the barrel needle 5 into the chlorine pipe 2 to stop chlorine and cut off the wind for insulation. Regulate the air pressure regulating valve 10 to maintain the furnace air pressure (displayed by the pressure transmitter 8) at 0.12Mpa±0.02Mpa, open the cooling water nozzle 9 (the cooling water temperature of the cooling water nozzle 9 is 25°C), cool the chlorine pipe 2 located outside the molten salt chlorination furnace 1 for 30 minutes, and then perform the salt return operation;

[0048] (3) Salt return operation

[0049] A first thermocouple 18 is arranged at a position 1 / 10 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1, and a second thermocouple 19 is arranged at a position 1 / 3 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1; the temperature measuring point No. 1 of the molten salt chlorination furnace 1 measured by the first thermocouple 18 is 600° C.-630° C. to prevent the molten salt from solidifying; the temperature measuring point No. 2 of the molten salt chlorination furnace 1 measured by the second thermocouple 19 is 820° C.-840° C. to reduce the fluidity of the molten salt, perform the salt return operation, and maintain this temperature during the salt return operation;

[0050] By gradually closing the air pressure regulating valve 10, the inlet air pressure (displayed by the pressure transmitter 8) is gradually reduced from 0.11Mpa to 0.06MPa. The height of the molten salt liquid level from the furnace bottom in the molten salt chlorination furnace 1 is monitored to be 4.9m. The pressure is stabilized for 2 minutes for every 0.01Mpa reduction in pressure. When the pressure is reduced to 0.06Mpa, the pressure in the chlorine gas system in front of the molten salt chlorination furnace and the pressure in the molten salt chlorination furnace 1 tend to be in a balanced state. The pressure is further reduced. The pressure is stabilized for 4 minutes for every 0.01Mpa reduction in pressure. Ensure that the molten salt in the molten salt chlorination furnace 1 is completely solidified before returning to the chlorine pipe 2 outside the molten salt chlorination furnace 1, until the air pressure regulating valve 10 is completely closed; at this time, first open the pressure relief valve 17 on the top of the chlorine buffer tank 14, and then open the chlorine pressure regulating valve 11 to relieve the pressure of the chlorine pipeline 7 in front of the furnace, and the pressure of the chlorine pipeline 7 in front of the furnace (pressure transmitter 8 display) is reduced to 0Mpa, and stabilized for 13 minutes. At this time, the molten salt returns to the flange of the tee 3 close to one side of the molten salt chlorination furnace 1 and is completely solidified, completing the salt return operation;

[0051] When gradually closing the air pressure regulating valve 10 or relieving the pressure of the chlorine gas pipeline 7 in front of the tube furnace and the pressure relief of the chlorine gas pipeline 7 in front of the furnace drops to 0Mpa, observe the temperature value displayed by the infrared thermometer 6 at the three-way 3 position in real time. If the temperature at the temperature measuring point rises sharply, immediately open the air pressure regulating valve 10 to supply air to prevent molten salt from entering the chlorine gas pipeline 7 in front of the furnace;

[0052] (4) Clean or replace the chlorine gas pipeline in front of the furnace

[0053] Remove the chlorine gas pipeline 7 in front of the furnace, and then blind the tee 3 with a blind plate to seal the chlorine gas pipe 2; clean or replace the chlorine gas pipeline 7 in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline 7 in front of the furnace; after the chlorine gas pipeline is reinstalled, pull out the barrel needle 5 to start the furnace production; before pulling out the barrel needle 5, close the pressure relief valve 17 on the top of the chlorine buffer tank 14, open the chlorine gas supply valve 16, and send chlorine to the chlorine buffer tank 14. The pressure of the chlorine buffer tank 14 is maintained at 0.15MPa; open the air pressure regulating valve 10 to maintain the furnace air pressure at 0.13Mpa, pull out the barrel needle 5 from the chlorine gas pipe 2 to the flange of the tee 3 close to the barrel needle sealing tube 4, and the high-temperature molten salt in the furnace will melt the previously solidified molten salt. After the barrel needle 5 is pulled out, close the air pressure regulating valve 10, and open the chlorine pressure regulating valve 11 at the same time. After the switch is completed, the furnace is restarted and the operation continues for six months. The continuous operation cycle reaches sixteen months, and the furnace is shut down and taken offline for maintenance.

[0054] Example 3

[0055] (1) Operation of molten salt chlorination system

[0056] like Figure 1-2 As shown, the chlorine system in front of the molten salt chlorination furnace includes a chlorine pipe 2, and cooling water nozzles 9 are installed on both sides of the chlorine pipe 2; the chlorine inlet of the chlorine pipe 2 is connected to the front chlorine pipeline 7 and the barrel needle sealing tube 4 through a tee 3, respectively, the barrel needle sealing tube 4 is connected to the tee 3 through a flange, the tee 3 is connected to the front chlorine pipeline 7 through a flange, and a barrel needle 5 is slidably installed at the outlet of the barrel needle sealing tube 4, the barrel needle 5 and the barrel needle sealing tube 4 are a packing sealing structure, when the barrel needle 5 is driven in, the barrel needle 5 passes through the tee 3 and the chlorine pipe 2 in sequence from the barrel needle sealing tube 4 to extend into the molten salt chlorination furnace 1, and when the barrel needle 5 is pulled out, the insertion end of the barrel needle 5 is located at the connecting flange between the tee 3 and the barrel needle sealing tube 4; it is used to measure the internal temperature of the tee 3; The air inlet end of the chlorine gas pipeline 7 in front of the furnace is connected to an air buffer tank 12 and a chlorine gas buffer tank 14 through an air pipeline and a chlorine gas pipeline respectively. The chlorine gas buffer tank 14 has a chlorine gas buffer tank pressure gauge and a pressure relief valve 17 installed on the top; a pressure transmitter 8 is installed on the chlorine gas pipeline 7 in front of the furnace, a chlorine gas pressure regulating valve 11 is installed on the chlorine gas pipeline, and an air pressure regulating valve 10 is installed on the air pipeline; an air pressure regulating main valve 13 is installed on the air inlet pipe of the air buffer tank 12, and an oxidation docking chlorine gas pipeline 15 is connected to the air inlet of the chlorine gas buffer tank 14, and the chlorine gas port of the oxidation docking chlorine gas pipeline 15 is connected to the tail gas exhaust pipe of the titanium tetrachloride oxidation furnace, and a chlorine gas supply valve 16 is provided on the oxidation docking chlorine gas pipeline 15;

[0057] The chlorine pipe 2 of the chlorine gas system in front of the molten salt chlorination furnace is installed at the chlorine inlet of the molten salt chlorination furnace 1, and is assembled into a molten salt chlorination system. The molten salt chlorination system is started and operated, and the air pressure regulating valve 10 is closed, and the chlorine gas supply valve 16, the chlorine gas pressure regulating valve 11 and the air pressure regulating main valve 13 are opened. Chlorine is introduced into the molten salt chlorination furnace 1 through the chlorine gas system in front of the molten salt chlorination furnace to carry out molten salt chlorination reaction. At this time, the pressure in the chlorine buffer tank 14 is maintained at 0.15MPa-0.16MPa. When the molten salt chlorination system is in operation, the height of the molten salt liquid level in the molten salt chlorination furnace 1 from the furnace bottom is maintained at 5m±0.2m; with the operation of the molten salt chlorination system, the inner wall of the chlorine gas pipeline 7 in front of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure of the chlorine buffer tank 14 gradually increases. After continuous operation for twelve months, the pressure of the chlorine buffer tank 14 reaches 0.3MPa, which affects the stable operation of the molten salt chlorination system, and the molten salt chlorination furnace 1 performs salt return operation;

[0058] (2) Preparation before salt return operation

[0059] Regulate the main air pressure regulating valve 13 to maintain the pressure of the air buffer tank 12 at 0.4Mpa±0.1Mpa, close the chlorine pressure regulating valve 11, and open the air pressure regulating valve 10 at the same time. After the chlorine pressure regulating valve 11 is completely closed, close the chlorine gas supply valve 16 and insert the barrel needle 5 into the chlorine pipe 2 to stop chlorine and cut off the wind for insulation. Regulate the air pressure regulating valve 10 to maintain the furnace air pressure (displayed by the pressure transmitter 8) at 0.12Mpa±0.02Mpa, open the cooling water nozzle 9 (the cooling water temperature of the cooling water nozzle 9 is 25°C), cool the chlorine pipe 2 located outside the molten salt chlorination furnace 1 for 30 minutes, and then perform the salt return operation;

[0060] (3) Salt return operation

[0061] A first thermocouple 18 is arranged at a position 1 / 10 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1, and a second thermocouple 19 is arranged at a position 1 / 3 of the height of the furnace body of the molten salt chlorination furnace 1 from the bottom of the furnace body of the molten salt chlorination furnace 1; the temperature measuring point No. 1 of the molten salt chlorination furnace 1 measured by the first thermocouple 18 is 630° C.-650° C. to prevent the molten salt from solidifying; the temperature measuring point No. 2 of the molten salt chlorination furnace 1 measured by the second thermocouple 19 is 860° C.-880° C. to reduce the fluidity of the molten salt, perform the salt return operation, and maintain this temperature during the salt return operation;

[0062] By gradually closing the air pressure regulating valve 10, the inlet air pressure (displayed by the pressure transmitter 8) is gradually reduced from 0.14Mpa to 0.07MPa. The height of the molten salt liquid level from the furnace bottom in the molten salt chlorination furnace 1 is monitored to be 5.2m. The pressure is stabilized for 2 minutes for every 0.01Mpa decrease in pressure. When the pressure drops to 0.07Mpa, the pressure in the chlorine gas system in front of the molten salt chlorination furnace and the pressure in the molten salt chlorination furnace 1 tend to be in a balanced state. The pressure is further reduced. The pressure is stabilized for 4 minutes for every 0.01Mpa decrease in pressure. Ensure that the molten salt in the molten salt chlorination furnace 1 is completely solidified before returning to the chlorine pipe 2 outside the molten salt chlorination furnace 1, until the air pressure regulating valve 10 is completely closed; at this time, first open the pressure relief valve 17 on the top of the chlorine buffer tank 14, and then open the chlorine pressure regulating valve 11 to relieve the pressure of the chlorine pipeline 7 in front of the furnace, and the pressure of the chlorine pipeline 7 in front of the furnace (pressure transmitter 8 display) is reduced to 0Mpa, and stabilized for 15 minutes. At this time, the molten salt returns to the flange of the tee 3 close to one side of the molten salt chlorination furnace 1 and is completely solidified, completing the salt return operation;

[0063] When gradually closing the air pressure regulating valve 10 or relieving the pressure of the chlorine gas pipeline 7 in front of the tube furnace and the pressure relief of the chlorine gas pipeline 7 in front of the furnace drops to 0Mpa, observe the temperature value displayed by the infrared thermometer 6 at the three-way 3 position in real time. If the temperature at the temperature measuring point rises sharply, immediately open the air pressure regulating valve 10 to supply air to prevent molten salt from entering the chlorine gas pipeline 7 in front of the furnace;

[0064] (4) Clean or replace the chlorine gas pipeline in front of the furnace

[0065] Remove the chlorine gas pipeline 7 in front of the furnace, and then blind the tee 3 with a blind plate to seal the chlorine gas pipe 2; clean or replace the chlorine gas pipeline 7 in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline 7 in front of the furnace; after the chlorine gas pipeline is reinstalled, pull out the barrel needle 5 to start the furnace production; before pulling out the barrel needle 5, close the pressure relief valve 17 on the top of the chlorine buffer tank 14, open the chlorine gas supply valve 16, and send chlorine to the chlorine buffer tank 14, and the pressure of the chlorine buffer tank 14 is maintained at 0.16Mpa; open the air pressure regulating valve 10 to maintain the furnace air pressure at 0.14Mpa, pull out the barrel needle 5 from the chlorine gas pipe 2 to the flange of the tee 3 close to the barrel needle sealing tube 4, the high-temperature molten salt in the furnace will melt the previously solidified molten salt, and after the barrel needle 5 is pulled out, close the air pressure regulating valve 10, and open the chlorine pressure regulating valve 11 at the same time. After the switch is completed, the furnace is restarted and the operation continues for four months. The continuous operation cycle reaches sixteen months, and the furnace is shut down and taken offline for maintenance.

[0066] Comparative Example 1

[0067] A parallel test was carried out according to step (1) of Example 2. Due to the scarring of the chlorine gas pipeline 7 in front of the furnace, the pressure of the chlorine gas buffer tank 14 reached 0.28 MPa, which had a certain impact on the stable operation of the molten salt chlorination system. According to conventional operation, the online cleaning of the chlorine gas pipeline 7 in front of the furnace could not be achieved. In order to ensure the stable operation of the molten salt chlorination system, the feed amount of the molten salt chlorination furnace needs to be reduced. At this time, as the pressure of the chlorine gas buffer tank 14 increases, the feed amount of the molten salt chlorination furnace 1 is gradually reduced from the previous 4.6 t / h to 4 t / h, and production is reduced.

[0068] After the implementation of this technical scheme, taking a 15,000 tons / year titanium dioxide production line as an example, the feed rate of the molten salt chlorination furnace (calculated as titanium tetrachloride input in the oxidation process) can be increased from the previous 4t / h (Comparative Example 1) to 4.6t / h (Example 2), and the titanium dioxide output can be increased by about 939 tons (0.6t / h*24h*150d÷2.3=939t) in 6 months. Referring to the titanium dioxide price index in July 2022, sales revenue can be increased by 16.43 million yuan (939t*17,500 yuan / ton).

[0069] The above are only specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A chlorine gas system for a molten salt chlorination furnace with a replaceable chlorine gas pipeline, comprising a chlorine pipe, characterized in that: Cooling water nozzles are installed on both sides of the chlorine pipe; the chlorine inlet of the chlorine pipe is connected to the furnace front chlorine pipeline and the barrel needle sealing tube through a tee, the tee is connected to the furnace front chlorine pipeline through a flange, and a barrel needle is slidably installed at the outlet of the barrel needle sealing tube. When the barrel needle is driven in, the barrel needle passes through the tee and the chlorine pipe in sequence through the barrel needle sealing tube and extends into the molten salt chlorination furnace. When the barrel needle is pulled out, the insertion end of the barrel needle is located at the connection between the tee and the barrel needle sealing tube; The air inlet end of the chlorine gas pipeline in front of the furnace is connected with an air buffer tank and a chlorine buffer tank through an air pipeline and a chlorine gas pipeline respectively; a pressure transmitter is installed on the chlorine gas pipeline in front of the furnace, a chlorine pressure regulating valve is installed on the chlorine gas pipeline, and an air pressure regulating valve is installed on the air pipeline; an air pressure regulating main valve is installed on the air inlet pipe of the air buffer tank, an oxidation-connected chlorine gas pipeline is connected to the air inlet of the chlorine gas buffer tank, a chlorine gas supply valve is provided on the oxidation-connected chlorine gas pipeline, and a pressure relief valve is installed on the top of the chlorine gas buffer tank.

2. The molten salt chlorination furnace front chlorine gas system with replaceable front chlorine gas pipeline according to claim 1, characterized in that: An infrared thermometer is provided at the tee to measure the internal temperature of the tee.

3. The molten salt chlorination furnace front chlorine gas system with replaceable front chlorine gas pipeline according to claim 1, characterized in that: A first pressure gauge is arranged on the pipeline between the air buffer tank and the air pressure regulating main valve, and a second pressure gauge is arranged on the pipeline between the chlorine buffer tank and the chlorine supply valve.

4. The molten salt chlorination furnace front chlorine gas system with replaceable front chlorine gas pipeline according to claim 1, characterized in that: The chlorine buffer tank is provided with a chlorine buffer tank pressure gauge.

5. The molten salt chlorination furnace front chlorine gas system with replaceable front chlorine gas pipeline according to claim 1 is characterized in that: The chlorine gas port of the oxidation-connected chlorine gas pipeline is connected to the tail gas emission pipe of the titanium tetrachloride oxidation furnace.

6. A long-term operation method for effectively increasing the feeding amount of a molten salt chlorination furnace in the later stage of operation by using the system of claim 1, characterized in that: The specific steps are as follows: (1) Operation of molten salt chlorination system The chlorine pipe of the chlorine gas system in front of the molten salt chlorination furnace is installed at the chlorine inlet of the molten salt chlorination furnace to assemble into a molten salt chlorination system. When the molten salt chlorination system is started, the air pressure regulating valve is closed, the chlorine gas supply valve, the chlorine gas pressure regulating valve and the air pressure regulating main valve are opened, and chlorine is introduced into the molten salt chlorination furnace through the chlorine gas system in front of the molten salt chlorination furnace to carry out the molten salt chlorination reaction; with the operation of the molten salt chlorination system, the inner wall of the chlorine gas pipeline in front of the chlorine gas system in front of the molten salt chlorination furnace is scarred, and the pressure in the buffer tank gradually increases. When the pressure in the buffer tank affects the stable operation of the molten salt chlorination system, the molten salt chlorination furnace performs salt return operation; (2) Preparation before salt return operation Adjust the main air pressure regulating valve to maintain the pressure of the air buffer tank at 0.3Mpa -0.5Mpa, close the chlorine pressure regulating valve, and open the air pressure regulating valve at the same time. After the chlorine pressure regulating valve is completely closed, close the chlorine gas supply valve and insert the barrel needle into the chlorine pipe to stop chlorine and cut off the wind for insulation. Adjust the air pressure regulating valve to maintain the air pressure entering the furnace at 0.10Mpa-0.14Mpa, open the cooling water nozzle, cool the chlorine pipe outside the molten salt chlorination furnace for 30 minutes, and then perform the salt return operation; (3) Salt return operation A first thermocouple is arranged at a position 1 / 10 of the height of the molten salt chlorination furnace body from the bottom of the molten salt chlorination furnace body, and a second thermocouple is arranged at a position 1 / 3 of the height of the molten salt chlorination furnace body from the bottom of the molten salt chlorination furnace body; the temperature of the No. 1 measuring point of the molten salt chlorination furnace measured by the first thermocouple is between 580°C and 650°C to prevent the molten salt from solidifying; the temperature of the No. 2 measuring point of the molten salt chlorination furnace measured by the second thermocouple is between 790°C and 880°C to reduce fluidity, perform salt return operation, and maintain this temperature during the salt return operation; By gradually closing the air pressure regulating valve, the air pressure entering the furnace is gradually reduced from 0.10Mpa-0.14Mpa to 0.06MPa-0.07MPa, and the pressure is stabilized for 2 minutes every time the pressure is reduced by 0.01Mpa; when the pressure is reduced to 0.06Mpa-0.07Mpa, the chlorine system in front of the molten salt chlorination furnace and the pressure in the molten salt chlorination furnace tend to be in a balanced state, and the pressure is continued to be reduced. The pressure is stabilized for 4 minutes every time the pressure is reduced by 0.01Mpa, to ensure that the molten salt in the molten salt chlorination furnace is returned to the chlorine pipe outside the molten salt chlorination furnace and is completely solidified until the air pressure regulating valve is completely closed; at this time, the pressure relief valve on the top of the chlorine buffer tank is opened first, and then the chlorine pressure regulating valve is opened to relieve the pressure of the chlorine gas pipeline in front of the furnace, and the pressure of the chlorine gas pipeline in front of the furnace is reduced to 0Mpa, and it is stabilized for 10 minutes to 15 minutes to complete the salt return operation; (4) Clean or replace the chlorine gas pipeline in front of the furnace Remove the chlorine gas pipeline in front of the furnace, and then blind the tee with a blind plate to seal the chlorine gas pipe; clean or replace the chlorine gas pipeline in front of the furnace, and after completion, remove the blind plate and reinstall the chlorine gas pipeline in front of the furnace; after the chlorine gas pipeline is reinstalled, pull out the barrel needle to start the furnace production; before pulling out the barrel needle, close the pressure relief valve on the top of the chlorine buffer tank, open the chlorine gas supply valve, and send chlorine to the chlorine buffer tank. The pressure of the chlorine buffer tank is maintained at 0.13 MPa-0.16Mpa, open the air pressure regulating valve to maintain the furnace air pressure at 0.10Mpa-0.14Mpa, pull out the barrel needle from the chlorine gas pipe to the flange of the tee close to the barrel needle sealing tube, the high-temperature molten salt in the furnace will melt the previously solidified molten salt, after the barrel needle is pulled out, close the air pressure regulating valve, and open the chlorine pressure regulating valve at the same time, and the furnace will be restarted after the switch is completed.

7. The long-period operation method for effectively increasing the feeding amount of the molten salt chlorination furnace in the later stage of operation according to claim 6 is characterized in that: Step (1) When the molten salt chlorination system is started, the pressure in the chlorine buffer tank is maintained at 0.13 MPa-0.16 MPa; when the pressure in the chlorine buffer tank reaches 0.26 MPa-0.3 MPa, which affects the stable operation of the molten salt chlorination system, the molten salt chlorination furnace needs to be operated to return salt.

8. The long-period operation method for effectively increasing the feeding amount of the molten salt chlorination furnace in the later stage of operation according to claim 6 is characterized in that: When the molten salt chlorination system is in operation, the height of the molten salt liquid level in the molten salt chlorination furnace from the furnace bottom is maintained at 4.8m-5.2m.

9. The long-period operation method for effectively increasing the feeding amount of the molten salt chlorination furnace in the later stage of operation according to claim 6 is characterized in that: In step (3), when the air pressure regulating valve is gradually closed or the pressure of the chlorine gas pipeline in front of the tube furnace is relieved and the pressure of the chlorine gas pipeline in front of the furnace is reduced to 0 MPa, the temperature value displayed by the infrared thermometer at the three-way position is observed in real time. If the temperature at the measuring point rises sharply, the air pressure regulating valve is immediately opened to supply air to prevent molten salt from entering the chlorine gas pipeline in front of the furnace.

10. The long-period operation method for effectively increasing the feeding amount of the molten salt chlorination furnace in the later stage of operation according to claim 6 is characterized in that: The cooling water temperature of the cooling water nozzle is ≤25℃.

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