A tail gas treatment device for methyl carbamate containing phosgene

Abstract

This invention relates to the field of exhaust gas treatment technology, specifically disclosing an exhaust gas treatment device for methyl carbamate containing phosgene, including an alkaline scrubbing tower, an inlet pipe, and an outlet pipe. The alkaline scrubbing tower is equipped with multiple alkaline solution feed pipes. The bottom of the alkaline scrubbing tower is connected to a collection tank, which is connected to a treatment tank. A pusher head assembly is installed in the collection tank, and the pusher head assembly is connected to a pusher power assembly, which drives the pusher head assembly to move. After the pusher power assembly moves a certain distance, it pushes the discharge baffle to rotate upwards. At this time, wastewater accumulates near the discharge baffle under the pusher head assembly's influence. The wastewater then flows out from the gap between the discharge baffle and the inner wall of the collection tank. During this process, the gap must always be smaller than the wastewater level. Finally, the bottom plate of the pusher head assembly presses against the discharge baffle, sealing the drain outlet again. The exhaust gas inside the alkaline scrubbing tower can only be discharged from the drain outlet after mixing with the alkaline solution.

Description

Technical Field

[0001] This invention belongs to the field of exhaust gas treatment technology, and specifically relates to an exhaust gas treatment device containing phosgene in methyl carbamate. Background Technology

[0002] The exhaust gas produced during the production of methyl carbamate contains a variety of harmful substances, such as MDI (toluene diisocyanate), PI (phenyl isocyanate), chlorobenzene, and phosgene, also known as carbonyl chloride (dichlorocarbonyl).

[0003] The Chinese patent CN 203264540 U discloses a device for destroying phosgene-containing exhaust gas, which consists of an exhaust gas buffer tank, a flow distribution station, and several phosgene treatment units. The exhaust gas from the exhaust gas buffer tank is distributed to the phosgene treatment units through the flow distribution station. The phosgene treatment units are composed of a falling film absorption tower, a catalytic decomposition tower, several acid washing towers, and an alkaline washing tower connected in sequence. The phosgene treatment units are also equipped with a water tank, which is connected to the falling film absorption tower, the catalytic decomposition tower, and the acid washing tower respectively.

[0004] However, when the above-mentioned device is used, the exhaust gas enters the alkaline scrubbing tower and mixes with the atomized alkaline solution. The resulting wastewater and some exhaust gas remain inside the alkaline scrubbing tower. The following problems arise during the discharge of this wastewater: First, as the alkaline solution level gradually decreases and the amount of alkaline solution decreases, some space gradually forms inside the discharge pipe. Exhaust gas flows through these spaces, causing the residual exhaust gas inside the alkaline scrubbing tower to be discharged directly without mixing with the alkaline solution, which can harm the health of surrounding personnel. Second, during the discharge process, some solution remains at the drain outlet. This solution is still alkaline, which will cause the drain outlet to corrode more quickly. Therefore, this application proposes a tail gas treatment device for methyl carbamate containing phosgene. Summary of the Invention

[0005] The purpose of this invention is to provide a tail gas treatment device for methyl carbamate containing phosgene, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a tail gas treatment device for methyl carbamate containing phosgene, comprising an alkaline scrubbing tower, an inlet pipe, and an outlet pipe, wherein the alkaline scrubbing tower is provided with multiple alkaline solution feed pipes.

[0007] The bottom of the alkaline washing tower is connected to a collection tank, which is connected to a treatment tank. A pusher head assembly is installed in the collection tank, and the pusher head assembly is connected to a pusher power assembly. The pusher power assembly drives the pusher head assembly to move, pushing the wastewater in the collection tank into the discharge port.

[0008] The collection pool is equipped with a discharge baffle, which is connected to an opening and closing component for opening and closing. When the discharge baffle is opened to the maximum angle, the bottom plate abuts against the outer wall of the discharge baffle.

[0009] The collection tank is equipped with a pusher blade at the location corresponding to the sewage outlet, and the pusher blade is connected to a drive component for rotating it.

[0010] An acidic solution storage tank is provided at the treatment pool. The acidic solution storage tank is connected to a discharge pipe inserted into the bottom of the treatment pool. The discharge pipe is inserted into the side of the separation plate near the collection pool.

[0011] Preferably, the pusher head assembly includes a pusher frame, the two end faces of which are respectively attached to the two inner walls of the collection tank. A base plate is installed at the lower end of the pusher frame, and a plurality of pusher inclined plates inclined toward the sewage outlet are provided at the lower end of the base plate. The pusher frame is connected to a lifting and lowering motor for driving it to lift or fall, and the lifting and lowering motor is installed on the slider.

[0012] Preferably, the slider is connected to the chute in the collection pool, the chute penetrates the outer wall of the collection pool near the treatment pool, and two sliders are provided, with the two sliders located at the two ends of the pusher plate respectively.

[0013] Preferably, the pushing power assembly includes a push-pull plate, which is inserted into the slide groove and connected to the output end of the cylinder.

[0014] Preferably, the bottom of the discharge baffle is provided with a U-shaped groove, and a U-shaped sealing gasket is installed in the U-shaped groove. When the discharge baffle is closed, the U-shaped sealing gasket abuts against the inner wall of the collection pool.

[0015] Preferably, the opening and closing assembly includes a lifting guide block and a pusher plate. The lifting guide block is located on the discharge baffle and is connected to the sealing seat via a rotating shaft. The lifting guide block has an arc-shaped working part on the side near the pusher head assembly. The center of the arc-shaped working part coincides with the center line of the rotating shaft. The pusher plate is mounted on the pusher head assembly, and the lifting guide block is aligned with the pusher plate.

[0016] Preferably, the drive assembly includes a transmission gear and a transmission rack. One end of the transmission rack is connected to a push-pull plate, and the other end is connected to the output end of the cylinder. The transmission rack is connected to the transmission gear through tooth meshing.

[0017] Preferably, a first connecting shaft is inserted at the center of the transmission gear. The first connecting shaft is connected to a second connecting shaft via a first gear and a second gear. The second connecting shaft is mounted on the mounting base via a bearing. The second connecting shaft is connected to the pusher blade via a sprocket and a chain.

[0018] Preferably, an intermediate shaft is inserted at the middle position of the pusher blade and inserted into the power chamber. Both the second connecting shaft and the intermediate shaft are equipped with sprockets, and the two sprockets are connected by a chain located in the power chamber.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. In this invention, the drain outlet is blocked by the feeding baffle. The feeding baffle will only be pushed to rotate upward after the pushing power component moves a certain distance. At this time, wastewater accumulates near the feeding baffle under the push of the pushing head component. Then, the wastewater flows out from the gap between the feeding baffle and the inner wall of the collection tank. During the process, the gap must always be smaller than the liquid level of the wastewater. Then, the bottom plate in the pushing head component presses against the feeding baffle, sealing the drain outlet again. The exhaust gas inside the alkali washing tower can only be discharged from the drain outlet after mixing with the alkali solution, avoiding the direct emission of the tail gas remaining in the alkali washing tower.

[0021] Second, the present invention provides a pusher blade at the sewage outlet. The cylinder pulls the transmission rack to move, which in turn drives the transmission gear to rotate. The transmission gear adjusts the rotation of the second connecting shaft through the first gear and the second gear. Then, the second connecting shaft and the pusher blade are connected by a sprocket and a chain. The rotation of the pusher blade can promote the flow of sewage, prevent it from blocking the sewage outlet, and prevent the sewage outlet from being corroded.

[0022] Third, this invention treats wastewater by introducing an acidic solution to neutralize the alkaline solution, and simultaneously sets up a separation plate to filter the neutralized wastewater, thereby treating and improving the wastewater.

[0023] IV. The pusher head assembly of this invention is equipped with components such as a pusher ramp, which allows it to fit against the lower inner wall of the collection tank. The pusher ramp is tilted towards the side closer to the sewage outlet. The lifting and lowering motor can drive the pusher frame to lift upward and lower downward. When the pusher head assembly moves to the right, the pusher ramp contacts the inner wall of the collection tank, which can push all the sewage in the collection tank into the sewage outlet. However, when the pusher head assembly moves to the left, in order to avoid friction between the pusher ramp and the inner wall of the collection tank, the height of the pusher frame and the pusher ramp is raised, and then it falls when it reaches the left side. In order to push all the wastewater in the collection tank into the sewage outlet, the pusher ramp fits tightly against the inner wall of the collection tank. When it moves to the left, it separates from the inner wall of the collection tank. The force required to move to the left is smaller and easier, and it will not cause excessive pushing force to the collection tank. At the same time, its movement speed is faster, so the discharge baffle falls faster and the exhaust gas is not easily discharged. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the tail gas treatment device for methyl carbamate containing phosgene in this invention.

[0025] Figure 2 In this invention Figure 1 Rear view.

[0026] Figure 3 This is one of the schematic diagrams of the internal structure of the collection pool in this invention.

[0027] Figure 4 This is the second schematic diagram of the internal structure of the collection pool in this invention.

[0028] Figure 5 For the present invention Figure 4 A schematic diagram of the structure at point A in the middle.

[0029] Figure 6 For the present invention Figure 4 A schematic diagram of the structure at point B.

[0030] Figure 7 For the present invention Figure 4 A schematic diagram of the structure at point C.

[0031] Figure 8 In this invention Figure 4 Rear view.

[0032] Figure 9 For the present invention Figure 8 A schematic diagram of the structure at point D.

[0033] In the diagram: 1. Alkali washing tower; 2. Inlet pipe; 3. Outlet pipe; 4. Alkali solution feed pipe; 5. Collection tank; 501. Chute; 6. Treatment tank;

[0034] 7. Pusher head assembly; 701. Pusher frame; 702. Base plate; 703. Pusher inclined plate; 704. Lifting and lowering motor; 705. Slider; 8. Pusher power assembly; 801. Push-pull plate; 802. Cylinder; 9. Discharge baffle; 10. Opening and closing assembly; 1001. Lifting guide block; 1002. Arc-shaped working part; 1003. Sealing seat; 1004. Pusher plate;

[0035] 11. Pusher blades; 12. Drive assembly; 1201. Transmission gear; 1202. Transmission rack; 1203. Second connecting shaft; 1204. Chain; 13. Acidic solution storage tank; 14. Separation plate. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Reference Figures 1-9 A tail gas treatment device for methyl carbamate containing phosgene includes an alkaline scrubbing tower 1, an inlet pipe 2, and an outlet pipe 3. The tail gas generated during the production of methyl carbamate contains various harmful substances, such as MD. The waste gas generated during the production of methyl carbamate, including methyl isocyanate (I), phenyl isocyanate (PI), chlorobenzene, and phosgene (also known as carbonyl chloride (dichlorocarbonyl)), is sent into the alkaline scrubbing tower 1 through the inlet pipe 2 after passing through the water scrubbing tower. The alkaline scrubbing tower 1 is equipped with multiple alkaline solution feed pipes 4, through which atomized alkaline solution is introduced. The alkaline solution enters the alkaline scrubbing tower 1 from top to bottom, while the tail gas enters the alkaline scrubbing tower 1 from the bottom inlet pipe 2 and flows from bottom to top. Its movement direction is opposite to that of the alkaline solution. During the mutual movement, the alkaline solution and tail gas mix and fall into the collection tank 5 at the bottom. The treated tail gas enters the next treatment unit from the top outlet pipe 3. There are two alkaline solution feed pipes 4, which are distributed vertically. The alkaline solution enters the alkaline scrubbing tower 1 through the upper and lower layers. Therefore, the concentration of alkaline solution in the lower part of the alkaline scrubbing tower 1 is relatively high, and the mixing with the tail gas is mainly in this area.

[0038] The bottom of the alkaline washing tower 1 is connected to the collection tank 5, and the collection tank 5 is connected to the treatment tank 6. After the alkaline solution and the tail gas are mixed, they enter the inside of the collection tank 5. A large amount of wastewater that has adsorbed the tail gas accumulates here and needs to be treated. Therefore, a pusher head assembly 7 is installed in the collection tank 5. The pusher head assembly 7 is connected to the pusher power assembly 8. The pusher power assembly 8 drives the pusher head assembly 7 to move and push the wastewater in the collection tank 5 into the treatment tank 6.

[0039] Specifically, the pusher head assembly 7 includes a pusher frame 701, whose two end faces respectively conform to the two inner walls of the collection tank 5. A base plate 702 is installed at the lower end of the pusher frame 701, and several pusher inclined plates 703 inclined towards the discharge port are provided at the lower end of the base plate 702. The pusher frame 701 is connected to an up-and-down motor 704 for driving it to rise or fall. The up-and-down motor 704 is mounted on a slider 705, and the slider 705 is connected to a groove in the collection tank 5. 501 connection, the chute 501 penetrates the outer wall of the collection tank 5 near the treatment tank 6, two sliders 705 are provided, and the two sliders 705 are respectively located at both ends of the pusher plate 703; the pusher head assembly 7 is provided with pusher plate 703 and other components, so that it can fit against the lower inner wall of the collection tank 5, and the pusher plate 703 is inclined towards the side near the sewage outlet, and the lifting and lowering motor 704 can drive the pusher frame 701 to lift upward and lower downward, such as Figure 3 As shown, when the pusher head assembly 7 moves to the right, the pusher inclined plate 703 contacts the inner wall of the collection tank 5, which can push all the sewage inside the collection tank 5 into the drain outlet. However, when the pusher head assembly 7 moves to the left, in order to avoid friction between the pusher inclined plate 703 and the inner wall of the collection tank 5, the height of the pusher frame 701 and the pusher inclined plate 703 is raised, and then lowered when it reaches the left side. In order to push all the wastewater inside the collection tank 5 into the drain outlet, the pusher inclined plate 703 fits tightly against the inner wall of the collection tank 5. When it moves to the left, it is separated from the inner wall of the collection tank 5, and the force required to move to the left is smaller and easier, and it will not cause excessive pushing force to the collection tank 5.

[0040] More specifically, the pusher power assembly 8 includes a push-pull plate 801, which is inserted into the slide groove 501 and connected to the output end of the cylinder 802;

[0041] Furthermore, a discharge baffle 9 is provided in the collection tank 5. The discharge baffle 9 is connected to an opening and closing component 10 for driving its opening and closing. When the discharge baffle 9 is open, the sewage outlet leaks out. At this time, the wastewater in the collection tank 5 can be pushed into the treatment tank 6. When the discharge baffle 9 is closed, the sewage outlet is closed. At this time, the wastewater in the collection tank 5 is sealed inside the collection tank 5, and the collection tank 5 is in a sealed state. This is to prevent the exhaust gas from being discharged directly from the bottom hole and entering the surrounding atmosphere when it is introduced. When the discharge baffle 9 is opened to the maximum angle, the bottom plate 702 abuts against the outer wall of the discharge baffle 9.

[0042] Specifically, the bottom of the discharge baffle 9 is provided with a U-shaped groove, and a U-shaped sealing gasket is installed in the U-shaped groove. When the discharge baffle 9 is closed, the U-shaped sealing gasket abuts against the inner wall of the collection pool 5. The opening and closing assembly 10 includes a lifting guide block 1001 and a pusher plate 1004. The lifting guide block 1001 is located on the discharge baffle 9, and the lifting guide block 1001 is connected to the sealing seat 1003 through a rotating shaft. Figure 3 As shown, the lifting guide block 1001 and the sealing seat 1003 can rotate relative to each other, and the connection between the two is sealed. This is to separate the sewage outlet from the main body of the collection tank 5 and prevent exhaust gas leakage.

[0043] More specifically, the lifting guide block 1001 has an arc-shaped working part 1002 on the side near the pusher head assembly 7. The center of the arc-shaped working part 1002 coincides with the center line of the rotating shaft. The pusher plate 1004 is set on the pusher head assembly 7, and the lifting guide block 1001 is aligned with the pusher plate 1004. When the pusher plate 1004 moves to the position of the lifting guide block 1001, it continues to move to the right, which will squeeze the lifting guide block 1001 and make it rotate upward around the rotating shaft. At this time, a gap is created between the discharge baffle 9 and the inner wall of the collection tank 5. Wastewater enters the drain outlet through the gap and is finally discharged from the drain outlet. A torsion spring can be installed at the discharge baffle 9. The torsion spring provides the force to make the discharge baffle 9 fit against the inner wall of the collection tank 5.

[0044] Furthermore, a pusher blade 11 is provided at the location of the sewage outlet in the collection tank 5. The pusher blade 11 is connected to a drive assembly 12 for rotating it. When the pusher blade 11 rotates, it can push the sewage to flow and prevent the sewage from staying at the sewage outlet.

[0045] It should be noted that the drive assembly 12 includes a transmission gear 1201 and a transmission rack 1202. One end of the transmission rack 1202 is connected to the push-pull plate 801, and the other end is connected to the output end of the cylinder 802. The transmission rack 1202 is connected to the transmission gear 1201 through gear meshing. A first connecting shaft is inserted at the center of the transmission gear 1201. The first connecting shaft is connected to a second connecting shaft 1203 through a first gear and a second gear. The second connecting shaft 1203 is mounted on the mounting base through bearings. The second connecting shaft 1203 is connected to the pusher blade 11 through a sprocket and a chain 1204. Specifically, the pusher blade 11... An intermediate shaft is inserted into the power chamber at the middle position. Both the second connecting shaft 1203 and the intermediate shaft are equipped with sprockets. The two sprockets are connected by a chain 1204, which is located in the power chamber. The cylinder 802 pulls the transmission rack 1202 to move, which in turn drives the transmission gear 1201 to rotate. The transmission gear 1201 adjusts the rotation of the second connecting shaft 1203 through the first gear and the second gear. Then, the second connecting shaft 1203 is connected to the pusher blade 11 through the sprocket and the chain 1204. The rotation of the pusher blade 11 can push the sewage to flow and prevent it from blocking the sewage outlet.

[0046] It should be noted that an acidic solution storage tank 13 is provided at the treatment tank 6. The acidic solution storage tank 13 is connected to a discharge pipe inserted into the bottom of the treatment tank 6. The discharge pipe is inserted into the side of the separation plate 14 near the collection tank 5. The acidic solution and the alkaline solution are mixed. After the wastewater is neutralized, the solid waste in it is separated by the separation plate 14. The filtered wastewater is located in the right side area of ​​the treatment tank 6.

[0047] Working principle:

[0048] The exhaust gas discharged from the water washing tower enters the alkaline washing tower 1 through the air inlet pipe 2. At the same time, the atomized alkaline solution is introduced into the alkaline washing tower 1 through the alkaline solution feed pipe 4. After the exhaust gas and alkaline solution are mixed, they enter the collection tank 5. The remaining exhaust gas is discharged from the air outlet pipe 3.

[0049] When it is necessary to discharge the sewage in the collection tank 5, the pusher head assembly 7 is moved by the pusher power assembly 8, so that the sewage moves towards the side closer to the sewage outlet. When the pusher plate 1004 reaches the position of the lifting guide block 1001, it continues to move to the right, which will squeeze the lifting guide block 1001 and make it rotate upward around the rotation axis. At this time, a gap is created between the discharge baffle 9 and the inner wall of the collection tank 5. The wastewater enters the sewage outlet through the gap and is finally discharged from the sewage outlet. After the sewage enters the treatment tank 6, it mixes with the acidic solution to neutralize the alkaline substances in the wastewater.

[0050] 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 tail gas treatment device for methyl carbamate containing phosgene, comprising an alkaline scrubbing tower (1), an inlet pipe (2), and an outlet pipe (3), characterized in that, Multiple alkaline solution feed pipes (4) are installed on the alkaline washing tower (1); The bottom of the alkaline washing tower (1) is connected to the collection tank (5), the collection tank (5) is connected to the treatment tank (6), a pusher head assembly (7) is installed in the collection tank (5), the pusher head assembly (7) is connected to the pusher power assembly (8), the pusher power assembly (8) drives the pusher head assembly (7) to move, and pushes the wastewater in the collection tank (5) into the sewage outlet; The collection pool (5) is provided with a discharge baffle (9), which is connected to an opening and closing assembly (10) for driving it to open and close. When the discharge baffle (9) is opened to the maximum angle, the bottom plate (702) abuts against the outer wall of the discharge baffle (9). The collection tank (5) is provided with a pusher blade (11) at the position corresponding to the sewage outlet. The pusher blade (11) is connected to a drive assembly (12) for driving it to rotate. An acidic solution storage tank (13) is provided at the treatment tank (6). The acidic solution storage tank (13) is connected to a discharge pipe inserted into the bottom of the treatment tank (6). The discharge pipe is inserted into the side of the separation plate (14) near the collection tank (5). The pushing power assembly (8) includes a push-pull plate (801), which is inserted into the slide groove (501) and connected to the output end of the cylinder (802); The opening and closing assembly (10) includes a lifting guide block (1001) and a pusher plate (1004). The lifting guide block (1001) is located on the discharge baffle (9). The lifting guide block (1001) is connected to the sealing seat (1003) through a rotating shaft. The lifting guide block (1001) has an arc-shaped working part (1002) on the side near the pusher head assembly (7). The center of the arc-shaped working part (1002) coincides with the center line of the rotation axis. The pusher plate (1004) is set on the pusher head assembly (7), and the lifting guide block (1001) is aligned with the pusher plate (1004).

2. The tail gas treatment device for methyl carbamate containing phosgene according to claim 1, characterized in that, The pusher head assembly (7) includes a pusher frame (701). The two end faces of the pusher frame (701) are respectively attached to the two inner walls of the collection tank (5). A base plate (702) is installed at the lower end of the pusher frame (701). Several pusher inclined plates (703) inclined towards the sewage outlet are provided at the lower end of the base plate (702). The pusher frame (701) is connected to an up-and-down motor (704) for driving it to rise or fall. The up-and-down motor (704) is installed on the slider (705).

3. The tail gas treatment device for methyl carbamate containing phosgene according to claim 2, characterized in that, The slider (705) is connected to the chute (501) in the collection pool (5). The chute (501) penetrates the outer wall of the collection pool (5) on the side near the treatment pool (6). There are two sliders (705), and the two sliders (705) are located at the two ends of the pusher plate (703).

4. The tail gas treatment device for methyl carbamate containing phosgene according to claim 1, characterized in that, The bottom of the discharge baffle (9) is provided with a U-shaped groove, and a U-shaped sealing gasket is installed in the U-shaped groove. When the discharge baffle (9) is closed, the U-shaped sealing gasket abuts against the inner wall of the collection pool (5).

5. The tail gas treatment device for methyl carbamate containing phosgene according to claim 1, characterized in that, The drive assembly (12) includes a transmission gear (1201) and a transmission rack (1202). One end of the transmission rack (1202) is connected to the push-pull plate (801), and the other end is connected to the output end of the cylinder (802). The transmission rack (1202) is connected to the transmission gear (1201) through tooth meshing.

6. The tail gas treatment device for methyl carbamate containing phosgene according to claim 5, characterized in that, A first connecting shaft is inserted at the center of the transmission gear (1201). The first connecting shaft is connected to the second connecting shaft (1203) through the first gear and the second gear. The second connecting shaft (1203) is mounted on the mounting base through the bearing. The second connecting shaft (1203) is connected to the pusher blade (11) through the sprocket and the chain (1204).

7. The tail gas treatment device for methyl carbamate containing phosgene according to claim 6, characterized in that, An intermediate shaft is inserted at the middle position of the pusher blade (11), and the intermediate shaft is inserted into the power chamber. Both the second connecting shaft (1203) and the intermediate shaft are equipped with sprockets, and the two sprockets are connected by a chain (1204), which is located in the power chamber.

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