Device and method for recovering organic matters in hydrogen chloride gas

Abstract

The invention discloses a device and a method for recovering organic matters in hydrogen chloride gas, and relates to the technical field of chemical environmental protection, the device comprises a falling film absorber and an acid storage tank, the falling film absorber adopts a vertical multi-tube-pass structure, and a tube pass is provided with a film distributor; an organic matter overflow pipe is arranged on the tank wall of the acid storage tank, the acid storage tank is communicated with the falling film absorber through a pipeline system, and a closed cooling jacket is arranged outside the tube pass of the falling film absorber; the film distributor comprises a top cover, a sealing disc and a film distribution cone, and the top cover is fixed to the top of the tube pass to form a closed cavity. The invention aims to solve the problems of hydrochloric acid product pollution, excessive tail gas VOCs (Volatile Organic Compounds), resource waste, environmental violation and the like caused by residual chlorobenzene in byproduct hydrogen chloride in the reaction of benzene and chlorine in the prior art. The device and the method have the advantages that efficient hydrogen chloride absorption and organic matter resource recovery are synchronously realized through the synergistic effect of gas-liquid mass transfer reinforcement, low-temperature stable control and continuous gravity phase splitting.

Description

Technical Field

[0001] This invention relates to the field of chemical environmental protection technology, and in particular to a device and method for recovering organic matter from hydrogen chloride gas. Background Technology

[0002] In existing technologies, the reaction of benzene and chlorine produces organic chlorinated liquid and hydrogen chloride gas as a byproduct. The hydrogen chloride contains organic matter, and even after low-temperature chlorobenzene washing, some chlorobenzene remains in the hydrogen chloride. This results in a high VOC content in the exhaust gas after hydrochloric acid absorption, polluting the environment and causing material waste.

[0003] Specifically, these organic impurities cause two problems in the subsequent hydrochloric acid absorption process: First, residual chlorobenzene dissolves in the hydrochloric acid product, resulting in abnormal color and odor of the by-product hydrochloric acid. Due to excessive organic impurities, it cannot meet industrial-grade standards, severely restricting its commercial value. Second, unabsorbed chlorobenzene escapes with the exhaust gas, causing excessive VOC emissions, violating environmental regulations, and resulting in the unnecessary loss of high-value raw material chlorobenzene, forming a vicious cycle of resource waste and environmental pollution.

[0004] To address the above technical problems, this invention discloses an organic matter recovery device and method in hydrogen chloride gas. This invention has the advantages of simultaneously achieving efficient absorption of hydrogen chloride and resource recovery of organic matter through the synergistic effect of enhanced gas-liquid mass transfer, low-temperature stable control and continuous gravity phase separation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an organic matter recovery device and method in hydrogen chloride gas. This invention addresses the technical problems in the prior art, such as residual chlorobenzene in the by-product hydrogen chloride during the reaction of benzene and chlorine, which leads to hydrochloric acid product pollution and excessive VOCs in the tail gas, resulting in resource waste and environmental violations. This invention has the advantages of simultaneously achieving efficient absorption of hydrogen chloride and resource recovery of organic matter through the synergistic effect of enhanced gas-liquid mass transfer, low-temperature stable control, and continuous gravity phase separation.

[0006] This invention is achieved through the following technical solution: This invention discloses an organic matter recovery device in hydrogen chloride gas, including a falling film absorber and an acid storage tank. The falling film absorber adopts a vertical multi-pass structure, and a film distributor is provided at the pass.

[0007] The acid storage tank is equipped with an organic overflow pipe on its wall. The acid storage tank is connected to the falling film absorber through a pipeline system. The falling film absorber is equipped with a closed cooling jacket on the outside of its tube side.

[0008] Furthermore, the membrane applicator includes a top cover, a sealing disc, and a membrane cone, wherein the top cover is fixed to the top of the tube to form a sealed chamber;

[0009] The sealing disc divides the chamber into an upper compartment and a lower compartment. The membrane cone is a cone-shaped body with a smaller upper part and a larger lower part. Its tip faces upward and fixes the connecting pipe. The large diameter end of the membrane cone is in clearance fit with the inner wall of the inner tube.

[0010] The membrane cone has an internal air outlet chamber, which is connected to the upper compartment via a connecting pipe. The membrane cone has a tapered structure that is smaller at the top and larger at the bottom, with the connecting pipe fixed at the tip, and the larger diameter end fitting with the inner pipe wall with a clearance. This design allows the liquid to spread along the cone surface and overflow evenly to the pipe wall, forming a continuous liquid film with controllable thickness.

[0011] Furthermore, a guide impeller is fixed to the outer wall of the connecting pipe, and the top of the connecting pipe is rotatably connected to the sealing disc. The kinetic energy of the acid drives the membrane cone to rotate, and the guide impeller fixed to the outer wall of the connecting pipe generates centrifugal force through rotation, causing the acid to form a spiral turbulent flow within the pipe. This flow mode breaks the traditional laminar boundary layer limitation, improves the radial mixing degree of the fluid, and avoids local concentration dead zones.

[0012] Furthermore, the rotation of the membrane cone reconstructs the liquid film through centrifugal force, and the gas and liquid paths are physically isolated, with the gas being discharged through the outlet chamber and the liquid film flowing downward through the annular channel.

[0013] Furthermore, the cooling water in the cooling jacket flows from bottom to top. This upward flow path extends the residence time of the cooling water in the high-temperature area, allowing it to fully absorb heat and avoid the problem of reduced cooling capacity caused by rapid temperature rise in the high-temperature area in a parallel flow design.

[0014] Furthermore, the piping system includes an inlet pipe, an acid circulation pipe, an acid return pipe, and a purified gas outlet pipe. The inlet pipe is connected to the lower air inlet of the falling film absorber tube for introducing hydrogen chloride gas containing organic matter.

[0015] The acid circulation pipeline is led out from the bottom outlet of the acid storage tank, connected in series with a centrifugal pump, and then connected to the top lower compartment of the falling film absorber; the acid reflux pipeline is connected to the bottom drain port of the falling film absorber tube and below the liquid level in the acid storage tank; the purified gas outlet pipe is connected to the upper compartment and is used to export the separated hydrogen chloride gas.

[0016] A method for recovering organic matter from hydrogen chloride gas using a recovery device includes the following steps:

[0017] Step 1: Pre-cool the pipe walls by introducing cooling water into the cooling jacket of the falling film absorber;

[0018] Step 2: The acid enters the lower compartment, impacting the guide impeller and driving the membrane cone to rotate, forming a uniform liquid film;

[0019] Step 3: Hydrogen chloride gas containing organic matter enters from the bottom of the tube and comes into counter-current contact with the liquid film; the purified gas is then discharged through the outlet chamber.

[0020] Step 4: The organic-rich acid solution is allowed to stand in the acid storage tank for phase separation. The lower layer of hydrochloric acid is circulated, and the upper layer of organic matter overflows and is collected.

[0021] Furthermore, after the gas comes into contact with the liquid film, it is vertically discharged through the gas outlet chamber inside the membrane cone, and the rotating membrane cone forces the acid to cover the entire cone surface through centrifugal force.

[0022] The present invention has the following advantages:

[0023] (1) This invention improves the uniformity of liquid film coverage and the tolerance to airflow disturbance by using the centrifugal force-forced film formation mechanism of the rotating film cone and the physical isolation design of the gas-liquid dual channels, thus solving the problem of liquid film tearing caused by high-speed airflow shearing in traditional static film covering. The built-in gas path structure separates the purified gas flow path from the liquid film flow area, avoiding vertical airflow impact. Combined with the acid liquid kinetic energy-driven rotating system with no additional energy consumption, it achieves full-area dynamic coverage of the film cone.

[0024] (2) This invention achieves the integration of gas-liquid mass transfer, cooling temperature control and phase separation oil discharge through the coordinated design of vertical multi-pass falling film absorber and hydrofluoric acid-lined storage tank; its core is to form a uniform hydrochloric acid liquid film on the inner wall of the tube through the film distributor (conical distributor), which comes into counter-current contact with the hydrogen chloride gas containing organic matter flowing from bottom to top, thereby improving the organic matter dissolution efficiency; the closed cooling jacket is circulated with constant temperature cooling water, which flows from bottom to top to remove the heat of absorption, maintain the low temperature environment, and enhance the absorption stability of hydrogen chloride; the acid storage tank is lined with a fluoroplastic layer to ensure corrosion resistance, and the overflow port in the middle and upper part uses the density difference to achieve gravity phase separation of organic matter and hydrochloric acid; the clean hydrochloric acid in the lower layer is continuously recycled to the falling film absorber through the circulation pipeline to form a closed-loop circulation of acid liquid, while the organic matter enriched in the upper layer is automatically separated and collected through the overflow weir, thereby realizing the continuous recovery of organic matter.

[0025] (3) The present invention uses a falling film absorber as a washing device, which occupies a small area, has a large contact surface, and integrates washing and cooling. At the same time, concentrated hydrochloric acid is used as the absorption medium for chlorobenzene in hydrogen chloride. The concentrated hydrochloric acid is a hydrogen chloride aqueous solution, and no other impurities are generated during the absorption process. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the internal structure of the falling film absorber of the present invention;

[0028] Figure 3 For the present invention Figure 2 A magnified schematic diagram of the structure at point A;

[0029] Figure 4 For the present invention Figure 3 A magnified schematic diagram of the structure at point B.

[0030] In the diagram: 1. Falling film absorber; 2. Acid storage tank; 3. Film distributor; 4. Inlet pipe; 5. Acid circulation pipeline; 6. Acid return pipeline; 7. Lower water inlet; 8. Upper water outlet; 9. Purified gas outlet pipe; 10. Organic matter overflow pipe; 11. Upper compartment; 12. Lower compartment; 13. Gas outlet chamber; 14. Guide impeller; 101. Inner pipe; 102. Cooling jacket; 301. Top cover; 302. Sealing disc; 303. Film distributor cone; 304. Connecting pipe. Detailed Implementation

[0031] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. In the description of the present invention, words such as "front", "rear", "left", and "right" that indicate orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0032] The embodiments disclose an organic matter recovery device in hydrogen chloride gas, such as Figures 1-4 As shown, it includes a falling film absorber 1 and an acid storage tank 2. The falling film absorber 1 adopts a vertical multi-tube structure, and a film distributor 3 (conical distributor) is provided at the tube side to make saturated hydrochloric acid form a uniform liquid film and flow downward along the inner wall of the tube side. The tube side of the falling film absorber 1 is equipped with a closed cooling jacket 102, and constant temperature circulating cooling water is introduced to remove the absorbed heat.

[0033] In addition, the acid storage tank 2 is a flat-bottomed vertical container with a fluoroplastic lining for corrosion resistance. An organic overflow pipe 10 is installed in the upper part of the tank wall to achieve gravity phase separation by utilizing the density difference between organic matter and saturated hydrochloric acid.

[0034] During system operation, hydrogen chloride gas containing organic matter enters from the lower part of the tube side of the falling film absorber 1, contacting the hydrochloric acid liquid film flowing on the inner wall of the tube side in a counter-current manner. After the organic matter is dissolved and captured by the liquid film, the purified gas is discharged from the top of the tube side. The hydrochloric acid carrying organic matter returns to the fluorocarbon-lined storage tank 2 through the bottom return pipe, where it settles and stratifies. The lower layer of clean hydrochloric acid is continuously washed by a pump to the top of the falling film absorber 1, while the upper layer, enriched with organic matter, automatically overflows to the collection tank through the side wall overflow weir. Cooling water flows from bottom to top in the shell side, maintaining a low-temperature absorption environment through heat exchange with the tube wall. This system integrates three functions: gas-liquid mass transfer, cooling and temperature control, and phase separation and oil discharge, forming a synergistic mechanism of closed-loop acid circulation and continuous separation of organic matter.

[0035] Specifically, such as Figures 1-2As shown, the falling film absorber 1 has an inlet pipe 4 at its bottom, allowing hydrogen chloride gas containing organic matter to be connected to the lower inlet of the tube side of the falling film absorber 1 via the inlet pipe 4; the acid circulation pipeline 5 is led out from the bottom outlet of the fluoroacid-lined storage tank 2, connected in series with a flange filter and an acid-resistant centrifugal pump, and then connected to the top inlet of the falling film absorber 1; the acid return pipeline 6 extends from the bottom drain outlet of the tube side of the falling film absorber 1 to below the liquid level inside the acid storage tank 2; the cooling water pipeline's inlet end is connected to the lower inlet 7 of the shell side of the falling film absorber 1, and the return end is led out from the upper outlet 8 of the shell side; the purified gas outlet pipe 9 is connected to the gas outlet at the top of the tube side; the organic matter overflow pipe 10 is led out from the overflow weir on the side wall of the acid storage tank 2, realizing the continuous separation of light phase organic matter.

[0036] To improve the mass transfer efficiency between hydrogen chloride gas containing organic matter and acid solution, a gas-liquid countercurrent contact design is commonly used in industry. Hydrogen chloride gas containing organic matter enters from the bottom of the inner tube 101 of the falling film absorber 1 and flows upwards, while the acid solution is uniformly distributed from the top of the inner tube 101 through the film distributor 3, forming a liquid film that flows downwards along the tube wall under gravity. In this countercurrent operation, the rising gas flows through the edge region of the film distributor 3, and its dynamic behavior interacts strongly with the downward-flowing liquid film. If the gas velocity or local turbulence intensity exceeds a critical threshold, the high-speed gas flow will generate shear disturbances on the liquid film surface, leading to disruption of the liquid film continuity (such as local tearing, splashing, or the formation of dry areas), thereby weakening the uniformity of liquid film coverage, reducing the effective gas-liquid contact area, and ultimately affecting the absorption efficiency of hydrogen chloride and the separation effect of organic matter.

[0037] This embodiment achieves physical isolation of the gas-liquid path by reconstructing the structure of the membrane distributor 3, thus avoiding the impact of the rising hydrogen chloride gas on the liquid film.

[0038] Specifically, such as Figures 2-4 As shown, the membrane distribution device 3 includes a top cover 301, a sealing plate 302, a membrane distribution cone 303, and a connecting pipe 304. The top cover 301 is fixed to the top of the tube side of the falling film absorber 1 by bolts, forming a sealed chamber. The sealing plate 302, which is axially arranged inside the chamber, divides it into upper and lower double compartments. The lower compartment 12 communicates with the cavity of the inner tube 101, while the upper compartment 11 is specially equipped with a purified gas outlet. Each inner tube 101 is equipped with a tapered membrane distribution body (membrane distribution cone 303) that is smaller at the top and larger at the bottom. Its tip faces upward and is fixed to the connecting pipe 304. The top of the connecting pipe 304 is connected to the sealing plate 302. The large-diameter end of the membrane distribution cone 303 faces downward and maintains a gap with the inner wall of the inner tube 101 (for liquid film formation). An exhaust chamber 13 is opened inside the membrane distribution cone 303, which communicates with the upper compartment 11 through the connecting pipe 304 that passes through the sealing plate 302. Acid circulation pipeline 5 is connected to the lower compartment 12, so that acid flows through the annular gap between the outer wall of the connecting pipe 304 and the inner wall of the inner pipe 101 to the inclined surface of the film cone 303, and forms a uniform liquid film by means of the cone surface guidance.

[0039] During the purification process, hydrogen chloride gas enters from the bottom of the inner tube 101 and rises, reacting in reverse with the acid liquid film flowing downwards along the tube wall. The purified gas after the reaction no longer directly impacts the liquid film at the gap in the membrane cone 303, but instead flows into the outlet chamber 13 inside the membrane cone 303, and is vertically introduced into the isolation chamber above the sealing disc 302 via the connecting pipe 304, finally being discharged through the purified gas outlet pipe 9. By internalizing the gas path (using the inner cavity of the membrane cone 303 as the gas channel) and externally annulating the liquid path (using the gap between the connecting pipe 304 and the inner tube 101 as the liquid distribution channel), gas-liquid flow separation is achieved, eliminating the shear disturbance of the liquid film on the tube wall caused by the high-speed airflow and ensuring the continuity and absorption stability of the liquid film.

[0040] In this embodiment, a rotational driving mechanism is introduced to address the issues of liquid film deviation, localized dry areas, and uneven coverage caused by the static distribution of the fixed membrane cone 303. When the membrane cone 303 is fixed, the acid flows naturally down the cone surface solely by gravity, making it susceptible to variations in surface tension distribution, resulting in a non-uniform liquid film. For example, some areas may have excessively thick liquid films, leading to dripping flow, while others may have excessively thin or broken liquid films, resulting in dry walls and significantly reducing gas-liquid contact efficiency.

[0041] Therefore, such as Figure 4 As shown, a guide impeller 14 is fixed to the outer wall of the connecting pipe 304, and the top of the connecting pipe 304 and the sealing disc 302 are designed as a rotating connection structure (axial limiting to prevent detachment). At the same time, it is ensured that the impeller is located below the top opening of the inner pipe 101, so that it is completely immersed in the acid inlet channel. When the acid enters from the top of the inner pipe 101, its flow kinetic energy directly impacts the blades of the guide impeller 14, converting the fluid kinetic energy into the impeller's rotational mechanical energy, thereby driving the connecting pipe 304 and the bottom membrane cone 303 to rotate synchronously.

[0042] The rotational motion of the film-forming cone 303 improves film quality through a centrifugal force-dominated liquid film reconstruction mechanism. When the acid flows to the rotating cone surface, it is accelerated and spread tangentially along the cone surface by the centrifugal force generated by the cone's rotation, forming a dynamic liquid film of uniform thickness. The centrifugal force forces the acid to overcome the surface tension gradient and local flow resistance, covering the entire cone surface, effectively suppressing the axial streamline aggregation phenomenon caused by gravity in static film formation. This dynamic film formation process gives the liquid film high uniformity, creating stable interfacial conditions for gas-liquid countercurrent mass transfer.

[0043] An apparatus and method for recovering organic matter from hydrogen chloride gas, comprising the following steps:

[0044] Step 1: Turn on the cooling water system of the shell side of the falling film absorber 1, and control the cooling water to flow from bottom to top to pre-cool the tube wall evenly.

[0045] Step 2: The acid inside the acid storage tank 2 enters the lower compartment 12 through the acid circulation pipeline 5 and also enters through the top opening of the inner pipe 101. It impacts the guide impeller 14 on the outer wall of the connecting pipe 304, converting the fluid's kinetic energy into mechanical energy, which drives the film cone 303 to rotate. The centrifugal acceleration generated by the rotating cone forces the acid to spread tangentially along the cone surface, forming a uniform liquid film that flows along the wall of the inner pipe 101.

[0046] Step 3: Hydrogen chloride gas containing organic matter enters through inlet pipe 4 and reacts in reverse with the rotating liquid film on the pipe wall. The purified gas flows into the outlet chamber 13 inside the membrane cone 303, and is vertically guided through the connecting pipe 304 into the upper compartment 11 of the sealing disc 302 for centralized discharge.

[0047] Step 4: The acid solution enriched with organic matter enters the fluorinated acid storage tank 2 through the return pipe and is allowed to stand to achieve density differential phase separation; the lower layer of clean hydrochloric acid is returned to the falling film absorber 1 by the circulation pump; the upper layer of light phase organic matter overflows and is collected through the organic matter overflow pipe 10.

[0048] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A device for recovering organic matter from hydrogen chloride gas, characterized in that, It includes a falling film absorber (1) and an acid storage tank (2). The falling film absorber (1) adopts a vertical multi-pass structure and a film distributor (3) is provided at the pass. The acid storage tank (2) is provided with an organic overflow pipe (10) on its wall. The acid storage tank (2) is connected to the falling film absorber (1) through a pipeline system. The falling film absorber (1) is provided with a closed cooling jacket (102) on the outside of its tube side.

2. The organic matter recovery device in hydrogen chloride gas as described in claim 1, characterized in that, The membrane applicator (3) includes a top cover (301), a sealing disc (302), and a membrane cone (303). The top cover (301) is fixed to the top of the tube to form a sealed chamber. The sealing disc (302) divides the chamber into an upper compartment (11) and a lower compartment (12). The membrane cone (303) is a cone-shaped body with a smaller upper part and a larger lower part. Its tip faces upward and fixes the connecting pipe (304). The large diameter end of the membrane cone (303) is in clearance fit with the inner wall of the inner tube (101). The membrane cone (303) has an air outlet chamber (13) inside, and the air outlet chamber (13) is connected to the upper compartment (11) via a connecting pipe (304).

3. The organic matter recovery device in hydrogen chloride gas as described in claim 2, characterized in that, The outer wall of the connecting pipe (304) is fixed with a guide impeller (14), and the top of the connecting pipe (304) is rotatably connected to the sealing disc (302). The acid liquid kinetic energy drives the membrane cone (303) to rotate.

4. The organic matter recovery device in hydrogen chloride gas as described in claim 2, characterized in that, The rotation of the membrane cone (303) reconstructs the liquid film through centrifugal force, and the gas-liquid paths are physically isolated. The gas is discharged through the gas outlet chamber (13), and the liquid film flows downward through the annular gap channel.

5. The organic matter recovery device in hydrogen chloride gas as described in claim 1, characterized in that, The cooling water in the cooling jacket (102) flows from bottom to top.

6. The organic matter recovery device in hydrogen chloride gas as described in claim 1, characterized in that, The pipeline system includes an inlet pipe (4), an acid circulation pipeline (5), an acid return pipeline (6), and a purified gas outlet pipe (9). The inlet pipe (4) is connected to the lower air inlet of the falling film absorber (1) for introducing hydrogen chloride gas containing organic matter. The acid circulation pipeline (5) is led out from the bottom outlet of the acid storage tank (2), connected in series with a centrifugal pump, and then connected to the lower compartment (12) at the top of the falling film absorber (1); the acid return pipeline (6) is connected to the bottom drain port of the falling film absorber (1) and below the liquid level in the acid storage tank (2); the purified gas outlet pipe (9) is connected to the upper compartment (11) and is used to export the separated hydrogen chloride gas.

7. A method for recovering organic matter from hydrogen chloride gas based on any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Introduce cooling water into the cooling jacket (102) of the falling film absorber (1) to pre-cool the pipe wall; Step 2: The acid enters the lower compartment (12), impacts the guide impeller (14), and drives the film cone (303) to rotate to form a uniform liquid film; Step 3: Hydrogen chloride gas containing organic matter enters from the bottom of the tube and comes into countercurrent contact with the liquid film. The purified gas is then discharged through the outlet chamber (13). Step 4: The organic-rich acid solution is allowed to stand and separate in the acid storage tank (2). The lower layer of hydrochloric acid is circulated, and the upper layer of organic matter overflows and is collected.

8. The method for recovering organic matter in hydrogen chloride gas as described in claim 7, characterized in that, After the gas comes into contact with the liquid film, it is vertically discharged through the gas outlet chamber (13) inside the membrane cone (303). The rotating membrane cone (303) forces the acid to cover the entire cone surface through centrifugal force.

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