An alkaline scrubbing device for treating polymerization tail gas

Abstract

An alkaline scrubbing device for treating polymerization tail gas relates to the field of chemical equipment technology. Through improvements to the alkaline scrubbing tower and subsequent pipelines, it solves the problem of clogging in the packing layer of traditional alkaline scrubbing towers when faced with self-polymerizing packing material, while also facilitating cleaning and maintenance. The device includes an alkaline scrubbing tower, a dryer, and a buffer tank connected sequentially by pipelines. Manholes are provided at the bottom of both the alkaline scrubbing tower and the buffer tank. A circulation pump is installed on the inner or outer side of the alkaline scrubbing tower. The inlet of the circulation pump is connected to a recovery chamber at the bottom of the alkaline scrubbing tower, and its outlet is connected to a spray chamber at the top of the alkaline scrubbing tower. The spray chamber is equipped with a multi-layer spray mechanism, which includes multiple nozzles spaced apart. The nozzles in each layer are staggered or spirally arranged from top to bottom. The lower part of the alkaline scrubbing tower is connected to an inlet pipeline for the waste gas to be treated.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, specifically to an alkaline scrubbing device for treating polymerization tail gas. Background Technology

[0002] Methyl 2,2,3,3-tetrafluoro-3-methoxypropionate (molecular formula C5H6F4O3, molecular weight 190.09) is a crucial high-end fluorochemical raw material and intermediate. It is a key precursor for the synthesis of perfluorocarboxylic acid resin monomers and fluorinated vinyl ethers, and is further used to prepare fluorinated carboxylic acid monomers required for the preparation of perfluorinated ion-exchange membranes, a core component of the chlor-alkali industry. In addition, this substance has wide applications in adhesives, dyes, pharmaceutical intermediates, and specialty fluoropolymers. Since its initial synthesis by DuPont in 1961, its unique molecular structure has ensured its important role in the synthesis of high-end materials.

[0003] In the production process of this substance, tetrafluoroethylene is usually reacted with dimethyl carbonate via an addition reaction, followed by post-processing. However, this production process has a significant technical problem: after the reaction is completed, a considerable portion of the high-value raw materials that did not participate in the reaction (such as tetrafluoroethylene) will dissolve in the waste liquid and enter the tail gas system with subsequent processes.

[0004] In existing technologies, the conventional method for treating this portion of the tail gas is as follows: after preliminary separation in a gas-liquid separator, the tail gas enters an alkaline scrubbing tower for washing and deacidification under the control of an inlet pressure regulating valve; the treated gas phase then enters a dryer for drying, is temporarily stored in a tail gas buffer tank, and is finally sent to a batching tank for reuse under the control of an outlet pressure regulating valve. However, in actual production operation, this tail gas treatment system has revealed many defects, which seriously restrict production efficiency and economic benefits, mainly in the following aspects: Frequent system blockage: The lack of manholes in the alkaline washing tower and tail gas buffer tank prevents the removal of accumulated self-polymers and residues, resulting in a reduced internal flow cross-section, increased system operating pressure, and a risk of overpressure.

[0005] Low efficiency of alkaline washing: The packing layer in the middle of the alkaline washing tower is blocked by the combination of powder entrained in the gas phase and sprayed alkaline solution, resulting in poor gas phase flow; at the same time, the original single-layer spray design has poor absorption efficiency, causing the pH value of the gas phase at the outlet of the alkaline washing tower to remain at an acidic level of around 5 for a long time.

[0006] Downstream equipment corrosion and contamination: The acidic tail gas and severe liquid carryover in the alkali washing tower cause serious corrosion of the subsequent carbon steel batching tanks. The corrosion further exacerbates the self-polymerization reaction in the tanks, requiring frequent and intensive shutdowns for manual cleaning. The dryer also needs to be frequently switched and replaced due to liquid carryover, resulting in monomer waste. The recovery system is incomplete, with incomplete and poorly designed recovery pipelines that are prone to blockage. When the main series needs cleaning, there is a lack of reliable backup recovery paths, affecting the continuity of production.

[0007] In summary, existing technologies not only waste the high-value raw material tetrafluoroethylene, but their exhaust gas treatment systems also suffer from low operating efficiency, high maintenance costs, and safety hazards, ultimately affecting the stable, efficient, and clean production of methyl 2,2,3,3-tetrafluoro-3-methoxypropionate, a high-value product. Therefore, it is urgent to develop an exhaust gas treatment system that can operate efficiently and stably and effectively recover valuable components. Utility Model Content

[0008] I. Technical problems to be solved This invention addresses the shortcomings of existing technologies by proposing an alkaline scrubbing device for treating polymerization tail gas. Through improvements to the alkaline scrubbing tower and subsequent pipelines, it solves the problem of blockage in the packing layer of traditional alkaline scrubbing towers when faced with self-polymerizing packing material, while also facilitating cleaning and maintenance.

[0009] II. Specific Technical Solutions An alkaline scrubbing device for treating polymerization tail gas includes an alkaline scrubbing tower, a dryer, and a buffer tank connected in sequence by pipelines. Manholes are provided at the bottom of both the alkaline scrubbing tower and the buffer tank. A circulation pump is installed on the inner or outer side of the alkaline scrubbing tower. The inlet of the circulation pump is connected to a recovery chamber at the bottom of the alkaline scrubbing tower, and its outlet is connected to a spray chamber at the top of the alkaline scrubbing tower. A multi-layer spray mechanism is installed in the spray chamber, comprising multiple nozzles spaced apart. The nozzles in each layer are either staggered or spirally arranged from top to bottom. An inlet pipeline for the waste gas to be treated is connected to the lower part of the alkaline scrubbing tower.

[0010] Implementation principle and working principle: By setting up a multi-layer spray mechanism and using staggered or spirally arranged nozzles, the radiation surface of each nozzle can completely fill all spaces in the alkali washing tower, greatly increasing the contact area and contact time between the alkali solution and the tail gas. This completely removes the packing layer in the alkali washing tower, eliminates the easily clogged packing layer, and eliminates the system operation difficulties caused by the self-polymerization of powder and alkali solution on the packing. It also forms a nearly full-coverage, dead-zone-free spray network, allowing the gas and liquid phases to carry out mass transfer reactions fully and efficiently. Compared with the complex packing layer, the spray mechanism structure is simpler, and the combination with the manhole design makes cleaning after long-term operation feasible and convenient.

[0011] Preferably, a first multi-channel connector is provided on the side of the circulating pump outlet connected to the spray chamber, and multiple outlets of the first multi-channel connector are respectively connected to each layer of the spray mechanism; an outlet control valve is provided at each outlet of the first multi-channel connector; the beneficial effect of this preferred embodiment is that the alkaline solution is distributed to each layer of the spray mechanism through the first multi-channel connector, and an outlet control valve is provided on each branch to achieve independent and precise flow control of each layer of spray; the spray of a specific number of layers can be flexibly opened or adjusted according to the actual air intake load and pollutant concentration to achieve on-demand distribution, saving energy while ensuring efficiency; when a nozzle of a certain layer needs to be repaired or cleaned, its branch can be closed separately without affecting the normal operation of other layers, realizing partial online maintenance.

[0012] Preferably, a main circulation valve is installed on the pipeline between the inlet end of the circulating pump and the recovery chamber; a main outlet valve is installed at the outlet end of the circulating pump. The beneficial effect of this preferred embodiment is that by installing a main circulation valve and a main outlet valve at the inlet and outlet of the circulating pump respectively, the start-up, shutdown and isolation control of the entire alkali circulation system can be realized. When the equipment needs major repair or long-term shutdown, the main valve can be completely closed to reliably isolate the pump and the tower, providing conditions for safe maintenance and facilitating overall regulation of the flow and pressure of the entire circulation system.

[0013] Preferably, an exhaust port is provided at the top of the spray chamber, and the exhaust port is connected to a cyclone separator via a pipeline. A regulating valve is provided on the pipeline between the cyclone separator and the exhaust port, and the outlet of the cyclone separator is connected to the inlet of the dryer. The beneficial effects of this preferred embodiment are that by adding a cyclone separator at the outlet of the alkali washing tower, the larger liquid droplets entrained in the airflow are separated using the principle of centrifugal force; the amount of air entering the cyclone separator is controlled by the regulating valve to optimize the separation efficiency; the alkali liquid entrained in the tail gas after alkali washing is effectively removed, greatly reducing the workload of the subsequent dryer; and the dryer's switching regeneration frequency is significantly reduced due to the reduced liquid at the inlet, thereby reducing unit waste and improving the stability of continuous system operation.

[0014] Preferably, isolation valves are provided at both the inlet and outlet ends of the cyclone separator; an exhaust manifold is provided at the outlet end of the buffer tank, and an exhaust manifold valve is provided on the exhaust manifold valve, with a second multi-way connector connected to the outlet end of the exhaust manifold valve; the beneficial effect of this preferred embodiment is that by providing isolation valves at both ends of the cyclone separator, it is constructed as an independently detachable functional module. The second multi-way connector is used after the buffer tank to distribute the treated exhaust gas to different users. By closing the isolation valves, the cyclone separator can be isolated from the system for online maintenance or replacement without affecting the main process flow; this solves the pain point of the original system having a single recovery path, realizes the flexible distribution of exhaust gas to multiple batching tanks, and avoids system shutdown due to blockage or maintenance of a single line.

[0015] Preferably, the outlet of the second multi-channel connector is connected to several exhaust branch pipes, and each exhaust branch pipe is equipped with a branch pipe control valve. The advantage of this preferred option is that by setting a branch pipe control valve on each exhaust branch pipe, the pipeline to each specific user can be independently switched on and off, which can accurately control the destination of the exhaust gas recovery, meet the needs of different production lines, and when a branch is blocked or needs maintenance, the branch can be closed separately without affecting the normal recovery of other branches.

[0016] Preferably, an exhaust branch is provided between the cyclone separator and the isolation valve at its outlet end. A branch control valve is installed on the exhaust branch, which is connected to the main exhaust pipe, with the connection point located on the outlet side of the main exhaust valve. The advantage of this preferred embodiment is that by providing an exhaust branch, connecting the outlet pipe of the cyclone separator module to the main pipe after the buffer tank, and equipping it with a branch control valve, this branch control valve can be opened when the isolation valves at both ends of the cyclone separator are closed, allowing the airflow to bypass the cyclone separator and directly enter the subsequent system. When the dryer and buffer tank malfunction and require temporary shutdown for maintenance, this bypass ensures the continued operation of the exhaust gas treatment system, guaranteeing production continuity.

[0017] The beneficial effects of this utility model are as follows: 1. By eliminating the easily clogged packing layer and innovatively adopting a multi-layered, staggered, or spirally arranged spray mechanism, the operational difficulties caused by packing layer adhesion are fundamentally eliminated. This not only simplifies the structure but also creates a dead-zone-free, fully covered spray network, greatly increasing gas-liquid contact efficiency.

[0018] 2. By adding modular cyclone separators and their isolation valves, and combining them with multi-channel connectors and branch valve designs, the system achieves independent maintenance of functional units and flexible distribution of exhaust gas. This allows for the efficient distribution of exhaust gas to different users without shutting down the entire line when a single device or specific pipeline needs maintenance, significantly improving the operational flexibility, availability, and continuous operation capability of the entire production unit.

[0019] 3. When core back-end equipment such as dryers or buffer tanks fail, a bypass can be activated to isolate them, ensuring that the exhaust gas treatment system does not stop. This design transforms a single point of failure that could cause a complete production shutdown into a localized problem that can be handled online, greatly reducing the risk of production interruption and individual waste, and directly improving economic benefits and production efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the working principle of the alkaline scrubbing device for treating polymerization tail gas according to this utility model.

[0021] Explanation of reference numerals in the attached figures: Alkali washing tower 1, dryer 2, buffer tank 3, manhole 4, air inlet pipe 5, exhaust branch 6, circulating pump 101, recovery chamber 102, spray chamber 103, spray mechanism 104, nozzle 105, first multi-way connector 106, circulating main valve 107, liquid outlet main valve 108, exhaust port 109, liquid outlet control valve 110, cyclone separator 201, regulating valve 202, isolation valve 203, exhaust main pipe 301, exhaust main valve 302, second multi-way connector 303, exhaust branch pipe 304, branch pipe control valve 305, branch control valve 601. Detailed Implementation

[0022] The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this utility model can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0023] like Figure 1 As shown: The present invention provides an alkaline scrubbing device for treating polymerization tail gas, comprising an alkaline scrubbing tower 1, a dryer 2 and a buffer tank 3 connected in sequence by pipelines.

[0024] During implementation, both the bottom of the alkali washing tower 1 and the buffer tank 3 are welded or flanged with DN500 manholes 4, which facilitates personnel to enter the interior after long-term system operation to thoroughly clean the accumulated self-polymers and residues, fundamentally solving the problem of internal blockage of the equipment.

[0025] A circulating pump 101 is installed on the outside of the alkaline washing tower 1, or it can be installed inside the tower depending on the space available. The inlet of the circulating pump 101 is connected to the recovery chamber 102 at the bottom of the alkaline washing tower 1 via a pipe, and its outlet is connected to the spray chamber 103 at the top of the alkaline washing tower 1. A circulating master valve 107 is installed on the inlet pipe of the circulating pump 101 to isolate the pump from the tower body; and a discharge master valve 108 is installed at its outlet to control the start and stop of the entire spray system.

[0026] In practice, a three-layer spraying mechanism 104 is fixedly installed inside the spray chamber 103, and can also be configured as a four-layer system depending on the size of the tower. Each layer of the spraying mechanism 104 includes multiple stainless steel vortex nozzles 105 spaced apart by branch pipes. Specifically, the nozzles 105 in the same layer are arranged in a staggered manner, while from top to bottom, the nozzles 105 in different layers are distributed in a spiral shape in space. This arrangement ensures that the alkali solution forms a fully covered, dead-zone-free spraying network on the cross-section of the tower, greatly increasing the gas-liquid contact area and time.

[0027] In practice, to achieve precise control of each spray layer, a first multi-channel connector 106, such as a four-way distributor, is installed on the pipeline connecting the outlet of the circulating pump 101 to the spray chamber 103. The three outlets of the first multi-channel connector 106 are connected to each spray mechanism 104 through independent pipelines, and an outlet control valve 110 is installed on each outlet pipeline. Operators can flexibly open some or all spray layers according to the air intake load to achieve energy saving while ensuring the washing effect.

[0028] The polymerization tail gas to be treated enters tangentially from the bottom of the alkaline washing tower 1 through the inlet pipe 5; the alkaline solution is drawn out from the recovery chamber 102 under the drive of the circulating pump 101, and is transported to the spraying mechanism 104 of each layer through the liquid outlet valve 108 and the first multi-channel connector 106. After being atomized by the nozzle 105, it is sprayed downward to fully contact the acidic tail gas flowing upward in the opposite direction and complete the neutralization reaction.

[0029] Specifically, an exhaust port 109 is provided at the top of the spray chamber 103; the exhaust port 109 is connected to a cyclone separator 201 through a pipe for preliminary gas-liquid separation of the wet tail gas after alkaline washing; a regulating valve 202 is installed on the connecting pipe to optimize the airflow conditions entering the cyclone separator 201; the outlet of the cyclone separator 201 is connected to the inlet of the dryer 2 through a pipe; in order to modularize the separation unit and facilitate maintenance, isolation valves 203 are installed at both the inlet and outlet of the cyclone separator 201.

[0030] During implementation, the qualified exhaust gas after deep drying by dryer 2 enters buffer tank 3 for temporary storage; the outlet of buffer tank 3 is connected to exhaust manifold 301, and exhaust manifold valve 302 is installed on the manifold; the outlet of exhaust manifold valve 302 is connected to a second multi-way connector 303; multiple outlets of the second multi-way connector 303 are respectively connected to exhaust branch pipes 304 leading to different production lines, and each exhaust branch pipe 304 is equipped with a branch pipe control valve 305; this design realizes flexible distribution of treated exhaust gas, solves the problem of single recovery path and easy blockage in the original system, and greatly improves operational flexibility.

[0031] To further improve the continuity of the entire system under fault conditions, the present invention provides an exhaust branch 6; the exhaust branch 6 is connected to the pipeline between the outlet end of the cyclone separator 201 and its adjacent isolation valve 203, and the other end is connected to the exhaust main pipe 301, with the connection point located on the outlet side of the exhaust main valve 302; a branch control valve 601 is installed on the exhaust branch 6.

[0032] Example of maintenance workflow: When dryer 2 or buffer tank 3 malfunctions and requires maintenance, the following operations can be performed to achieve non-stop maintenance: Close the isolation valve 203 at the outlet of cyclone separator 201 and the inlet and outlet valves of dryer 2 (not shown in the figure) to isolate the faulty unit from the system; open the branch control valve 601 on exhaust branch 6; at this time, the tail gas from alkaline washing tower 103, after preliminary liquid removal by cyclone separator 201, no longer passes through dryer 2 and buffer tank 3, but directly enters exhaust main pipe 301 through exhaust branch 6, and is then distributed to available batching tanks through the second multi-way connector 303. Thus, the system can maintain continuous operation when core back-end equipment fails, ensuring production safety and efficiency.

[0033] Although embodiments of the present 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 present invention, the scope of which is defined by the appended claims.

Claims

1. An alkaline scrubbing device for treating polymerization tail gas, comprising an alkaline scrubbing tower (1), a dryer (2), and a buffer tank (3) connected in sequence by pipelines, wherein a manhole (4) is provided at the bottom of both the alkaline scrubbing tower (1) and the buffer tank (3), characterized in that: A circulation pump (101) is provided on the inner or outer side of the alkaline washing tower (1). The inlet end of the circulation pump (101) is connected to the recovery chamber (102) at the bottom of the alkaline washing tower (1), and its outlet end is connected to the spray chamber (103) at the top of the alkaline washing tower (1). A multi-layer spray mechanism (104) is provided in the spray chamber (103). The spray mechanism (104) includes multiple nozzles (105) arranged at intervals. The nozzles (105) of each layer are arranged alternately or spirally from top to bottom. The lower part of the alkaline washing tower (1) is connected to the air inlet pipe (5) for the waste gas to be treated.

2. The alkaline scrubbing device for treating polymerization tail gas according to claim 1, characterized in that: A first multi-channel connector (106) is provided on the side where the outlet end of the circulating pump (101) is connected to the spray chamber (103). Multiple outlet ends of the first multi-channel connector (106) are respectively connected to each layer of spray mechanism (104). An outlet control valve (110) is provided at each outlet end of the first multi-channel connector (106).

3. The alkaline scrubbing device for treating polymerization tail gas according to claim 1, characterized in that: A circulation master valve (107) is provided on the pipeline between the inlet end of the circulation pump (101) and the recovery chamber (102); a discharge master valve (108) is provided on the outlet end of the circulation pump (101).

4. The alkaline scrubbing device for treating polymerization tail gas according to claim 1, characterized in that: The top of the spray chamber (103) is provided with an exhaust port (109), and the exhaust port (109) is connected to a cyclone separator (201) through a pipeline. A regulating valve (202) is provided on the pipeline between the cyclone separator (201) and the exhaust port (109). The air outlet of the cyclone separator (201) is connected to the air inlet of the dryer (2).

5. The alkaline scrubbing device for treating polymerization tail gas according to claim 4, characterized in that: Isolation valves (203) are provided at both the inlet and outlet ends of the cyclone separator (201); an exhaust manifold (301) is provided at the outlet end of the buffer tank (3), an exhaust valve (302) is provided on the exhaust manifold (301), and a second multi-channel connector (303) is connected to the outlet end of the exhaust valve (302).

6. The alkaline scrubbing device for treating polymerization tail gas according to claim 5, characterized in that: The outlet of the second multi-channel connector (303) is connected to several exhaust branch pipes (304), and each of the exhaust branch pipes (304) is provided with a branch pipe control valve (305).

7. The alkaline scrubbing device for treating polymerization tail gas according to claim 5, characterized in that: An exhaust branch (6) is provided between the cyclone separator (201) and the isolation valve (203) at its outlet end. A branch control valve (601) is provided on the exhaust branch (6). The exhaust branch (6) is connected to the exhaust main pipe (301), and the connection point is located on the outlet end side of the exhaust main valve (302).

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