Separation and recovery device and method of epichlorohydrin phase transfer catalyst

Abstract

The present application relates to the technical field of catalyst separation and recovery, in particular to a device and method for separating and recovering a phase transfer catalyst for epichlorohydrin, which comprises a settling tank, a recovery device connected to the settling tank, a filtered liquid recovery device, a washing liquid recovery device and a filter cake recovery device connected to the liquid discharge port of the recovery device, the liquid discharge ports of the filtered liquid recovery device and the washing liquid recovery device are connected to the liquid inlet of the settling tank to form a circulation loop, and the recovery device is provided with a filtered liquid discharge port, a washing liquid discharge port and a filter cake discharge port, which are respectively connected to the filtered liquid recovery device, the washing liquid recovery device and the filter cake recovery device. The present application effectively reduces the energy consumption of the system, realizes effective recovery of the oil phase, the oil phase recovery rate is greater than or equal to 99.9%, effectively reduces the organic content in the wastewater, reduces the treatment capacity of the wastewater stripping device, and effectively reduces the nitrogen supplement amount through the circulation of the vacuum tail gas, thereby reducing the nitrogen consumption.

Description

Technical Field

[0001] This invention relates to the field of catalyst separation and recovery technology, specifically to a separation and recovery apparatus and method for epichlorohydrin phase transfer catalysts. Background Technology

[0002] The production of epichlorohydrin from hydrogen peroxide by oxidizing chloropropylene requires the use of a catalyst. The catalyst needs to be recovered and reused from the obtained product to reduce production costs. Currently, centrifuges are commonly used to recover the catalyst. However, centrifuge recovery is cumbersome and can cause catalyst emulsification, resulting in significant catalyst loss. Therefore, there is an urgent need for a catalyst separation and recovery device and method that is easy to operate, has a high recovery rate, and effectively reduces system energy consumption. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a separation and recovery device and method for epichlorohydrin phase transfer catalyst, so as to solve the problems of cumbersome operation, large catalyst loss and low recovery rate when using centrifuge to recover catalyst, and the inability to recover a large amount at one time.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a separation and recovery device for epichlorohydrin phase transfer catalyst, comprising a settling tank, a recovery device connected to the settling tank, a filtrate recovery device, a washing liquid recovery device, and a filter cake recovery device connected to the drain port of the recovery device, wherein the drain ports of the filtrate recovery device and the washing liquid recovery device are both connected to the inlet of the settling tank to form a circulation loop;

[0005] The recycling equipment is equipped with a filtrate drain outlet, a washing liquid drain outlet, and a filter cake discharge outlet, which are respectively connected to the filtrate recycling device, the washing liquid recycling device, and the filter cake recycling device.

[0006] Furthermore, the filtrate recovery device includes a filtrate buffer tank connected to the recovery equipment, an oil phase recovery tank and a filtrate catalyst tank connected to the filtrate buffer tank, and the drain ports of the oil phase recovery tank and the filtrate catalyst tank are both connected to a settling tank.

[0007] Furthermore, the filtrate buffer tank is provided with a first oil phase drain port and a first aqueous phase drain port. The first oil phase drain port is connected to the oil phase recovery tank, and the aqueous phase drain port is connected to the filtrate catalyst tank.

[0008] Furthermore, the filtrate catalyst tank is provided with a second aqueous phase drain port and a catalyst-containing aqueous phase drain port. The second aqueous phase drain port is connected to the wastewater stripping device, and the catalyst-containing aqueous phase drain port is connected to the settling tank.

[0009] Furthermore, the washing liquid recovery device includes a washing liquid buffer tank connected to the recovery equipment, and the drain port of the washing liquid buffer tank is connected to the recovery equipment.

[0010] Furthermore, the filter cake recovery device includes a catalyst receiving tank, which is provided with a washing liquid inlet and a catalyst suspension outlet.

[0011] Furthermore, the recycling equipment is equipped with a recycling equipment circulation cooler for condensing the exhaust gas inside the recycling equipment, and the condensed washing liquid is discharged from the recycling equipment circulation cooler.

[0012] The recovery equipment has a low-pressure nitrogen inlet.

[0013] Furthermore, the settling tank is equipped with a raw material inlet, a second oil phase drain outlet, and a catalyst-containing washing liquid drain outlet.

[0014] The method for separating and recovering epichlorohydrin phase transfer catalysts utilizes the separation and recovery equipment described above.

[0015] (1) The material enters the settling tank and is separated into an oil phase and a catalyst-containing aqueous phase. The catalyst-containing aqueous phase enters the recovery equipment.

[0016] (2) The product is separated into an aqueous phase, a catalyst-containing washing liquid, and a filter cake by a recovery device;

[0017] (3) The aqueous phase enters the filtrate recovery device, the catalyst-containing washing liquid enters the washing liquid recovery device, and the filter cake enters the filter cake recovery device; the filtrate recovery device removes most of the aqueous phase, and the oil phase and the remaining aqueous phase containing the catalyst are returned to the settling tank for repeated separation and recovery; the catalyst-containing washing liquid enters the settling tank for repeated separation and recovery after passing through the washing liquid recovery device; the filter cake is discharged after being suspended by the washing liquid.

[0018] (4) The exhaust gas from the recovery equipment is cooled by the circulation cooler of the recovery equipment, and part of it is circulated by the vacuum pump and part of it is discharged to the exhaust gas treatment device.

[0019] Furthermore, (1) the material enters the settling tank for oil-water phase separation, separating it into an oil phase and a catalyst-containing water phase. The upper oil phase overflows to the oil phase recovery system, and the lower catalyst-containing water phase flows into the recovery equipment by gravity.

[0020] (2) The recovery equipment is divided into a filtration zone, a washing zone and a drying zone: In the filtration zone, the material is evenly distributed by the distributor, and most of the aqueous phase is filtered. The aqueous phase flows by gravity to the filtrate buffer tank outside the recovery equipment. The filter cake after filtering most of the aqueous phase enters the washing zone and is washed with allyl chloride oil to wash away liquid impurities in the filter cake and improve the purity of solid components in the filter residue. The washing liquid after washing enters the washing liquid buffer tank. The filter cake after being washed with allyl chloride oil enters the catalyst receiving tank.

[0021] (3) The filtrate buffer tank is used for oil-water phase separation. The oil phase overflows from the upper layer to the oil phase recovery tank for buffering and is then transported to the settling tank for recovery by the oil phase recovery transfer pump. The aqueous phase flows by gravity to the filtrate catalyst tank under level control. The upper aqueous phase is sent to the wastewater stripping process, and the lower aqueous phase containing the catalyst is transported to the settling tank for recovery by the catalyst recovery pump. The washing liquid containing the catalyst is buffered in the washing liquid buffer tank and then transported to the settling tank for recovery by the washing liquid transfer pump. The filter cake entering the catalyst receiving tank is prepared with allyl chloride to a certain concentration and then transported to the catalyst storage tank for reuse by the catalyst suspension transfer pump.

[0022] (4) The exhaust gas from the recovery equipment is cooled by the circulation cooler of the recovery equipment, and part of it is circulated by the vacuum pump and part of it is discharged to the exhaust gas treatment device.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention can achieve a feed solids content of 20% to 30%, which is significantly higher than the 6% to 8% of centrifuges; the recovery rate of the catalyst recovered by the recovery equipment is ≥99%, and the catalyst content after filtration can reach more than 70%, which greatly improves the solid-liquid separation effect of the filtrate and effectively reduces the system energy consumption; it can achieve effective recovery of the oil phase, with an oil phase recovery rate of ≥99.9%, effectively reducing the organic matter content in wastewater and reducing the processing capacity of the wastewater stripping device; the circulation of vacuum tail gas can effectively reduce the amount of nitrogen replenishment and reduce the unit consumption of nitrogen. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device connection according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the internal structure of the recycling equipment according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Example 1:

[0029] Depend on Figure 1 As shown, the component numbers in this embodiment are as follows:

[0030] Settling tank 1, raw material inlet 11, second oil phase drain 12, catalyst-containing washing liquid drain 13

[0031] Recovery device 2, filtrate drain 21, washing liquid drain 22, filter cake discharge 23, low-pressure nitrogen inlet 24.

[0032] Filtrate buffer tank 3, first oil phase drain port 31, first aqueous phase drain port 32.

[0033] Oil phase recovery tank 4, oil phase recovery transfer pump 41,

[0034] Filtrate catalyst tank 5, second aqueous phase drain 51, catalyst-containing aqueous phase drain 52, catalyst recovery pump 53.

[0035] Washing liquid buffer tank 6, washing liquid transfer pump 61,

[0036] Catalyst receiving tank 7, washing liquid inlet 71, catalyst suspension outlet 72, catalyst suspension transfer pump 73.

[0037] Recovery equipment circulating cooler 8, vacuum pump 81.

[0038] A separation and recovery device for epichlorohydrin phase transfer catalyst includes a settling tank 1, which has a raw material inlet 11, a second oil phase outlet 12, and a catalyst-containing washing liquid outlet 13. The epichlorohydrin reaction liquid from the oxidation process enters through the raw material inlet 11. A recovery device 2 is connected to the catalyst-containing washing liquid outlet of the settling tank 1. The upper oil phase overflows into the oil phase recovery system through the second oil phase outlet 12, while the lower catalyst-containing aqueous phase flows by gravity into the recovery device 2. The recovery device 2 has a filtrate recovery device, a washing liquid recovery device, and a filter cake recovery device connected to its outlet. The recovery device 2 has a filtrate outlet 21, a washing liquid outlet 22, and a filter cake outlet 23, which are respectively connected to the filtrate recovery device, the washing liquid recovery device, and the filter cake recovery device. The outlets of the filtrate recovery device and the washing liquid recovery device are both connected to the inlet of the settling tank 1, forming a circulation loop to continuously recover unseparated catalyst and oil phase, minimizing catalyst loss.

[0039] The filtrate recovery device includes a filtrate buffer tank 3 connected to the filtrate drain port 21 of the recovery device 2. The filtrate buffer tank 3 has a first oil phase drain port 31 and a first aqueous phase drain port 32. An oil phase recovery tank 4 is connected to the first oil phase drain port 31 of the filtrate buffer tank 3, and a filtrate catalyst tank 5 is connected to the first aqueous phase drain port 32 of the filtrate buffer tank 3. The filtrate catalyst tank 5 has a second aqueous phase drain port 51 and a catalyst-containing aqueous phase drain port 52. The second aqueous phase drain port 51 is connected to a wastewater stripping device, and the catalyst-containing aqueous phase drain port 52 is connected to a settling tank 1. A catalyst recovery pump 53 is installed on the catalyst-containing aqueous phase drain port 52 to pump out the catalyst-containing aqueous phase. The drain port of the oil phase recovery tank 4 is connected to the settling tank 1, and an oil phase recovery transfer pump 41 is installed on the drain port of the oil phase recovery tank 4 to pump out the oil phase.

[0040] The washing liquid recovery device includes a washing liquid buffer tank 6 connected to the washing liquid drain port 22 of the recovery device 2, and the drain port of the washing liquid buffer tank 6 is connected to the settling tank 1. A washing liquid transfer pump 61 is also provided on the drain port of the washing liquid buffer tank 6 for pumping out the liquid.

[0041] The filter cake recovery device includes a catalyst receiving tank 7 connected to the filter cake discharge port 23 of the recovery equipment 2. The catalyst receiving tank 7 is provided with a washing liquid inlet 71 and a catalyst suspension discharge port 72. The liquid entering through the washing liquid inlet 71 is allyl chloride. The catalyst suspension discharge port 72 is provided with a catalyst suspension transfer pump 73. The catalyst suspension formed after allyl chloride suspends the catalyst is pumped out from the catalyst suspension discharge port 72 through the catalyst suspension transfer pump 73.

[0042] The recovery device 2 is equipped with a low-pressure nitrogen inlet 24 and a recovery device circulation cooler 8. The low-pressure nitrogen inlet 24 introduces low-pressure nitrogen into the recovery device 2. The exhaust gas of the recovery device 2 is cooled by 5-degree water in the recovery device circulation cooler 8. Part of the exhaust gas is circulated by the vacuum pump 81 and part of it is discharged to the exhaust gas treatment device. The recovery device 2 has a fully enclosed design. The slight positive pressure inside the recovery device 2 is controlled by adjusting the exhaust gas discharge rate at the outlet of the vacuum pump 81.

[0043] A method for separating and recovering epichlorohydrin phase transfer catalyst, using the above-mentioned separation and recovery equipment, includes the following recovery methods:

[0044] (1) The material enters the settling tank 1 for oil-water phase separation, separating it into an oil phase and a catalyst-containing water phase. The upper oil phase overflows to the oil phase recovery system, and the lower catalyst-containing water phase flows into the recovery equipment 2 by gravity.

[0045] (2) The recovery equipment 2 is divided into a filtration zone, a washing zone and a drying zone: In the filtration zone 100, the material is evenly distributed by the distributor, filtering most of the water phase. The water phase flows by gravity to the filtrate buffer tank 3 outside the recovery equipment 2; the filter cake after filtering most of the water phase enters the washing zone 200 and is washed with allyl chloride oil to wash away liquid impurities in the filter cake and improve the purity of solid components in the filter residue. The washing liquid after washing enters the washing liquid buffer tank 6; the filter cake after being washed with allyl chloride oil enters the catalyst receiving tank 7.

[0046] (3) The oil phase is separated into oil and water phases in the filtrate buffer tank 3. The oil phase overflows from the upper layer to the oil phase recovery tank 4 for buffering and is then transported to the settling tank 1 for recovery by the oil phase recovery transfer pump 41. The water phase flows by gravity to the filtrate catalyst tank 5 under level control. The upper water phase is sent to the wastewater stripping process, and the lower water phase containing the catalyst is transported to the settling tank 1 for recovery by the catalyst recovery pump 53. The washing liquid containing the catalyst is buffered in the washing liquid buffer tank 6 and then transported to the settling tank 1 for recovery by the washing liquid transfer pump 61. The filter cake entering the catalyst receiving tank 7 is prepared with allyl chloride to a certain concentration and then transported to the catalyst storage tank for reuse by the catalyst suspension transfer pump 73.

[0047] (4) The exhaust gas from the recovery device 2 is cooled by the recovery device circulation cooler 8, and part of it is circulated by the vacuum pump 81 and part of it is discharged to the exhaust gas treatment device.

[0048] Example 2:

[0049] Depend on Figure 2 As shown, the component numbers in this embodiment are as follows:

[0050] Filtration zone 100, washing zone 200, drying zone 300, enclosed hood 1, vacuum tank 2, vacuum disc 3, drive cylinder 4, filter belt 5, vacuum switching valve 6, drive roller 7, transmission roller 8, material trough 9, nozzle 11, catalyst washing nozzle 12, filter belt washing nozzle 13, scraper 14, tensioning cylinder 15, swing bracket 16, tensioning roller 17, pneumatic guide 18, filter belt limit switch 19, filter cake collection mechanism 20.

[0051] The structure of the recycling equipment in Example 1 includes a frame, a closed cover 1 on the outside of the frame, a vacuum chamber on the frame, a filter cloth mechanism on the outer periphery of the vacuum chamber, a cleaning mechanism, a tensioning mechanism, and a correction mechanism on the filter cloth mechanism, and several vacuum tanks 2 connected to the vacuum chamber.

[0052] The vacuum chamber includes a vacuum disc 3 and a grid plate on the vacuum disc. A drive cylinder 4 is provided on one side of the vacuum disc 3 to drive the vacuum disc 3 to reciprocate following the filter belt 5. The vacuum chamber is divided into a filtration zone 100, a washing zone 200, and a drying zone 300. Vacuum tanks 2 are respectively connected to the vacuum discs 3 in the filtration zone 100, washing zone 200, and drying zone 300 for recovering the filtrate and washing liquid, respectively. The vacuum tank 2 is an automatic draining container that separates gas and liquid and drains liquid without losing vacuum. The vacuum tank 2 is equipped with a vacuum switching valve 6, including a vacuum valve and a venting valve, with the two valves operating in opposite directions; used to control the pressure in the vacuum chamber so that the vacuum disc 3 adsorbs the filter belt 5 at intervals.

[0053] The filter cloth mechanism includes a drive roller 7 and several transmission rollers 8 arranged around the vacuum chamber. A filter belt 5 is supported on both the drive roller 7 and the transmission rollers 8. The filter belt 5 is made of materials such as PE, PP, and non-woven fabric with a mesh size of approximately 250 mesh, is anti-static, and can be used normally in a chloropropylene environment. The drive roller 7 is equipped with a motor and a reducer. After deceleration, the drive roller, which is lined with acid and alkali resistant rubber, rotates. The reducer is a variable speed reducer, making the filter belt's operating speed adjustable.

[0054] The filter belt 5 advances due to friction between itself and the drive roller 7 and transmission roller 8. The vacuum chamber is surrounded by the filter belt 5. When the vacuum chamber is under negative pressure, the filter belt 5 is attracted by the upper end of the vacuum chamber, and the liquid on the filter belt 5 is sucked away.

[0055] The enclosed cover 1 is equipped with a feeding mechanism located directly above the filtration zone 100 of the vacuum chamber. The feeding mechanism includes a fishtail-shaped material distribution trough 9, which contains several guide ribs. The outlet of the material distribution trough 9 is located above the filter belt 5. Multiple feeding points can be selected in the material distribution trough 9 to ensure the slurry is evenly distributed on the filter belt 5. This feeding mechanism is a commonly used structure.

[0056] The cleaning mechanism includes a nozzle 11 and nozzles located at the end of the nozzle 11. The nozzles include a catalyst washing nozzle 12 and a filter belt washing nozzle 13. The catalyst washing nozzle 12 is located directly above the filtration zone 100 of the vacuum chamber and is used to wash the catalyst. The filter belt washing nozzle 13 is located below the vacuum chamber and is used to wash the filter belt after the catalyst cake has been removed, ensuring that the filter belt pores remain intact. Allyl chloride is used as the washing solution. Multiple catalyst washing nozzles and filter belt washing nozzles are provided to ensure complete rinsing of the filter belt.

[0057] A filter cake stripping mechanism, consisting of a scraper 14, is provided on one side of the drive roller 7. This mechanism is used to strip the catalyst filter cake from the filter belt 5. When the filter belt 5, dragged by the drive roller 7, carries the dried filter cake to the drive roller 7, the filter cake automatically cracks due to the decrease in the radius of curvature. The thin scraper then peels off the filter cake and discharges it. A filter cake collecting mechanism 20 is located directly below the filter cake stripping mechanism. The filter cake collecting mechanism 20 has a square-to-round structure, through which the filter cake is collected into the collection tank.

[0058] The tensioning mechanism includes a tensioning cylinder 15 fixed to the frame, a swing bracket 16 located at the output end of the tensioning cylinder 15, and a tensioning roller 17 fixed on the swing bracket 16. The tensioning roller 17 is used to tension the filter belt 5.

[0059] The correction device includes pneumatic guides 18 symmetrically arranged on both sides of the filter belt to prevent the filter belt from folding and wrinkling and to correct the filter belt from running off track.

[0060] A filter belt limit switch 19 is provided on one side of the filter cloth mechanism.

[0061] The sealed enclosure is equipped with a micro-positive pressure interface, an oxygen content measurement interface, a nitrogen inlet interface, and a multi-point washing liquid interface; nitrogen is added through the nitrogen inlet interface to adjust the oxygen content inside the sealed enclosure.

[0062] The sealed cover is equipped with a control mechanism and anti-static facilities.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A separation and recovery device for epichlorohydrin phase transfer catalyst, characterized in that: It includes a settling tank, a recycling device connected to the settling tank, and a filtrate recycling device, a washing liquid recycling device, and a filter cake recycling device connected to the drain port of the recycling device. The drain ports of the filtrate recycling device and the washing liquid recycling device are both connected to the inlet of the settling tank to form a circulation loop. The recovery equipment is equipped with a filtrate drain outlet, a washing liquid drain outlet, and a filter cake discharge outlet, which are respectively connected to the filtrate recovery device, the washing liquid recovery device, and the filter cake recovery device. The recycling equipment is equipped with a recycling equipment circulation cooler, which is used to condense the exhaust gas in the recycling equipment, and the condensed washing liquid is discharged from the recycling equipment circulation cooler. The recovery equipment is equipped with a low-pressure nitrogen inlet; The recycling equipment includes a frame with a closed cover on the outside, a vacuum chamber on the frame, and a filter cloth mechanism on the outer periphery of the vacuum chamber. The filter cloth mechanism includes a filter belt made of PE, PP or non-woven fabric. The recycling equipment is divided into a filtration zone, a washing zone and a drying zone. The washing zone is washed with chloropropylene oil.

2. The separation and recovery device for epichlorohydrin phase transfer catalyst according to claim 1, characterized in that: The filtrate recovery device includes a filtrate buffer tank connected to the recovery equipment, an oil phase recovery tank and a filtrate catalyst tank connected to the filtrate buffer tank, and the drain ports of the oil phase recovery tank and the filtrate catalyst tank are both connected to a settling tank.

3. The separation and recovery device for epichlorohydrin phase transfer catalyst according to claim 2, characterized in that: The filtrate buffer tank is provided with a first oil phase drain port and a first aqueous phase drain port. The first oil phase drain port is connected to the oil phase recovery tank, and the first aqueous phase drain port is connected to the filtrate catalyst tank.

4. The separation and recovery device for epichlorohydrin phase transfer catalyst according to claim 2, characterized in that: The filtrate catalyst tank is equipped with a second aqueous phase drain port and a catalyst-containing aqueous phase drain port. The second aqueous phase drain port is connected to the wastewater stripping device, and the catalyst-containing aqueous phase drain port is connected to the settling tank.

5. The separation and recovery device for epichlorohydrin phase transfer catalyst according to claim 1, characterized in that: The washing liquid recovery device includes a washing liquid buffer tank connected to the recovery equipment, and the drain port of the washing liquid buffer tank is connected to a settling tank.

6. The separation and recovery device for epichlorohydrin phase transfer catalyst according to claim 1, characterized in that: The filter cake recovery device includes a catalyst receiving tank, which is equipped with a washing liquid inlet and a catalyst suspension outlet.

7. The separation and recovery device for the epichlorohydrin phase transfer catalyst according to claim 1, characterized in that: The settling tank is equipped with a raw material inlet, a second oil phase drain outlet, and a catalyst-containing washing liquid drain outlet.

8. A method for separating and recovering epichlorohydrin phase transfer catalyst, comprising using the separation and recovery apparatus according to any one of claims 1-7, characterized in that: (1) The material enters the settling tank for oil-water phase separation, separating into an oil phase and a catalyst-containing water phase. The upper oil phase overflows to the oil phase recovery system, and the lower catalyst-containing water phase flows into the recovery equipment by gravity. (2) The recovery equipment is divided into a filtration zone, a washing zone and a drying zone: In the filtration zone, the material is evenly distributed by the distributor, and most of the water phase is filtered. The water phase flows by gravity to the filtrate buffer tank outside the recovery equipment. The filter cake after filtering most of the water phase enters the washing zone and is washed with allyl chloride oil to wash away liquid impurities in the filter cake and improve the purity of solid components in the filter residue. The washing liquid after washing enters the washing liquid buffer tank. The filter cake after being washed with allyl chloride oil enters the catalyst receiving tank. (3) The filtrate buffer tank is used for oil-water phase separation. The oil phase overflows from the upper layer to the oil phase recovery tank for buffering and is then transported to the settling tank for recovery by the oil phase recovery transfer pump. The aqueous phase flows by gravity to the filtrate catalyst tank under level control. The upper aqueous phase is sent to the wastewater stripping process, and the lower aqueous phase containing the catalyst is transported to the settling tank for recovery by the catalyst recovery pump. The washing liquid containing the catalyst is buffered in the washing liquid buffer tank and then transported to the settling tank for recovery by the washing liquid transfer pump. The filter cake entering the catalyst receiving tank is prepared with allyl chloride to a certain concentration and then transported to the catalyst storage tank for reuse by the catalyst suspension transfer pump. (4) The exhaust gas from the recovery equipment is cooled by the circulation cooler of the recovery equipment, and part of it is circulated by the vacuum pump and part of it is discharged to the exhaust gas treatment device.

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