Filtering device for byproduct hydrochloric acid of phosgenation product

Abstract

The utility model discloses a phosgenation product byproduct hydrochloric acid filtering device, and aims to solve the problems of high cost, high pollution risk, non-ideal treatment effect and the like in the traditional treatment method. The device comprises a first resin column and a second resin column, a specific resin combination technology is adopted, sulfate radicals, ferric ions and organic pollutants in the byproduct hydrochloric acid are synergistically removed through the physical adsorption effect of resin, and the chromaticity and purity of the hydrochloric acid are remarkably improved. A PLC automatic control system is adopted in the device, starting and stopping of a valve and a pump are automatically adjusted according to the liquid level and hydrochloric acid transparency, and the stability and high efficiency of the purification process are guaranteed. Besides, through COD (Chemical Oxygen Demand) on-line monitoring of backwashing water, environmental protection and high efficiency of the backwashing process are ensured, the backwashing water can be recycled after being treated, and zero discharge of wastewater is realized. The device is simple in structure, convenient to operate and high in energy efficiency, and is an effective solution for treating the byproduct hydrochloric acid in the phosgenation reaction process.

Description

Technical Field

[0001] This utility model relates to the chemical industry, specifically to a filtration device for hydrochloric acid, a byproduct of phosgenation. Background Technology

[0002] Phosgeneification is an important synthetic process widely used in the production of polymers and fine chemical products such as polycarbonates and isocyanates. This reaction typically uses phosgene (generated by the reaction of carbon monoxide and chlorine) as a raw material, which reacts with hydroxyl-containing compounds (such as phenols and alcohols) or amino-containing compounds (such as amines) under liquid or gas phase conditions to produce the corresponding target products such as carbonates and isocyanates.

[0003] In this reaction, phosgene, as a reactive intermediate, releases a large amount of hydrogen chloride gas during addition or substitution reactions. To control the pressure in the apparatus and improve reaction safety, the generated hydrogen chloride gas is usually absorbed by water in a tail gas absorption tower, forming hydrochloric acid with a concentration ranging from 10% to 30%. Although this byproduct hydrochloric acid has high acidity and some utilization value, it often contains various impurities due to the complexity of the reaction system, the diversity of raw materials, and the materials used in the equipment.

[0004] The main contaminants include: residual organic matter from the reaction (such as benzene, toluene, aniline, etc.), sulfides carried in the raw materials (forming sulfate impurities), and iron ions (ferrous and ferric ions) introduced by equipment corrosion. The presence of ferric ions often causes hydrochloric acid to have a yellow to yellowish-brown appearance, making it unsuitable for downstream applications such as electronic and pharmaceutical grades, which have strict requirements for acid purity and color. Furthermore, the sulfate content in by-product hydrochloric acid often exceeds industrial-grade standards, further limiting its widespread use as a raw material acid.

[0005] Traditional byproduct hydrochloric acid purification processes, such as filtration, oxidation, adsorption, and sedimentation, can remove particulate matter, iron oxide ions, or some organic impurities to a certain extent, but they often have the following drawbacks: First, a large amount of chemical reagents (such as barium chloride) needs to be added to precipitate sulfate and iron ions, which poses the risk of secondary pollution and high treatment costs; second, colloidal ferric hydroxide in the precipitate is difficult to remove completely by ordinary filtration, resulting in residual iron content that may still exceed the standard; third, the process is complex, energy-intensive, and has a low degree of automation, which is not conducive to continuous industrial operation; finally, color improvement is limited, and the adsorption materials have a weak ability to remove low concentrations of dissolved aromatic organic compounds.

[0006] Therefore, in order to meet the need for deep purification of hydrochloric acid produced as a byproduct during the phosgenation reaction, it is urgent to develop a purification device that is simple in structure, automatically controlled, highly efficient in operation, has a significant purification effect, and avoids the use of chemical agents, so as to achieve the synergistic removal of metal ions, sulfate ions, and organic pollutants in the byproduct hydrochloric acid, while improving its color quality and resource utilization value. Utility Model Content

[0007] To address the aforementioned problems, this utility model provides a filtration device for hydrochloric acid, a byproduct of phosgenation.

[0008] This utility model is achieved through the following technical solution:

[0009] The present invention provides a filtration device for hydrochloric acid byproduct of phosgenation, comprising a first resin column and a second resin column. The first resin column and the second resin column have the same structure, the main body being a container with resin inside, an inlet at the top, and an outlet on the circumferential surface at the bottom.

[0010] The feed inlet of the first resin column is connected to the feed pipe. The feed pipe is equipped with a solenoid valve, a Y-type filter and a hydrochloric acid pump in sequence from the material inlet direction. A solenoid valve is provided at the connection between the feed pipe and the feed inlet of the first resin column.

[0011] The pumping direction of the above-mentioned hydrochloric acid pump is from the incoming material direction to the first resin column;

[0012] The second resin column is connected to the first resin column via a lifting pipe; one end of the lifting pipe is connected to the outlet of the first resin column, and the other end is connected to the inlet of the second resin column; a solenoid valve is provided at the connection point between the lifting pipe and the first resin column and the second resin column respectively.

[0013] The outlet of the second resin column is connected to the discharge pipe, and a solenoid valve is installed on the discharge pipe.

[0014] The first and second resin columns are structurally symmetrical, both using vertically positioned cylindrical containers, which facilitates stable resin layer distribution and uniform liquid flow. This symmetrical design ensures the repeatability and process continuity of operations such as resin loading, replacement, and backwashing. The two resin columns are arranged in series and connected by a lifting pipe to achieve efficient and synergistic removal of ionic and organic contaminants sequentially.

[0015] The ASD-003 resin packed in the first resin column is a strongly acidic cation exchange resin, mainly composed of sulfonated styrene-divinylbenzene copolymer, often existing in sodium form. ASD-003 exhibits excellent ion exchange capacity, showing high selectivity for ferric, ferrous, calcium, and magnesium ions, and can operate stably under strongly acidic conditions, making it suitable for the typical low pH environment of byproduct hydrochloric acid. The resin's pore size and specific surface area are optimized to ensure a synergistic removal effect on sulfate ions through charge shielding and weak complexation mechanisms.

[0016] The ASD-100 resin packed in the second resin column is a macroporous adsorption resin. Its framework material is a styrene-divinylbenzene cross-linked copolymer with a pore size ranging from -nm. Its surface is hydrophobically modified, exhibiting significant adsorption affinity for organic molecules. ASD-100 is particularly suitable for adsorbing low-polarity or neutral organic compounds such as benzene, alkanes, and aromatic amines, including aniline, toluene, and benzene. These impurities are often the root cause of the yellowing color of the byproduct hydrochloric acid. Its macroporous structure allows it to accommodate higher molecular weight organic pollutants while avoiding clogging and possessing good regeneration performance.

[0017] By sequentially configuring two functionally complementary resins, ASD-003 and ASD-100, the simultaneous removal of ionic and organic impurities can be achieved in a one-step process without introducing any chemical agents, forming the core innovative combination of this utility model.

[0018] Furthermore, the aforementioned first resin column comprises:

[0019] Resin containers in the form of cans;

[0020] A resin layer that is fixedly connected inside a resin container, radially filling the container, and having space between the upper and lower ends of the resin container;

[0021] The outlet of the first or second resin column is located at the lower end of the resin layer.

[0022] The resin container is made of pressure-bearing structural materials, such as acid-resistant fiberglass, fluoropolymer-lined steel, or polypropylene, capable of withstanding the chemical and physical loads from continuous acidic liquid operation. The resin bed fills the interior of the container without occupying the top and bottom space, allowing for sufficient liquid distribution and uniform flow throughout the entire resin bed. The height-to-diameter ratio of the resin bed is controlled at 4:1, a result optimized by combining adsorption kinetics, pressure drop stability, and backwashing efficiency, effectively preventing resin compaction and channel effects.

[0023] For ASD-003 resin, maintaining a high aspect ratio of 4:1 ensures that its ion exchange layer has sufficient thickness to handle high concentrations of iron ions and sulfate impurities without saturating too quickly; at the same time, maintaining an appropriate flow rate (10 BV / h) balances contact time and throughput, meeting the needs of continuous industrial operation. Similarly, ASD-100 requires controlling the bed thickness while maintaining a certain degree of fluid distribution uniformity to ensure that organic matter is fully adsorbed and to avoid breakthrough.

[0024] Furthermore, a fixing mesh is provided on the upper and lower end faces of the resin layer respectively; the fixing mesh is fixedly connected to the inner wall of the resin container; the outer edge contour of the fixing mesh is the same as the cross-section of the resin layer.

[0025] The design of the fixed mesh screen prevents the resin layer from floating or migrating during liquid flow impact or backwashing, ensuring that the resin remains stably in its effective adsorption position. The mesh screen material must possess acid resistance and structural stability, and is typically made of polypropylene fiber or fluorinated stainless steel wire mesh. Its pore size is designed to be smaller than the resin particle size (usually 300-500μm), effectively preventing resin particles from being lost with the liquid flow. The mesh screen is secured to the inner wall of the resin container by welding or flange clamping, enhancing structural stability and ensuring no detachment during long-term operation.

[0026] Furthermore, a liquid distributor is fixed inside the resin container; the liquid distributor is located at the upper end of the resin layer and the lower end of the inlet.

[0027] The liquid distributor is located above the resin bed. Through a multi-point outlet or a uniformly distributed circumferential perforation design, it ensures that the byproduct hydrochloric acid entering the resin column is evenly distributed vertically throughout the entire bed, preventing single-point impacts from causing resin disturbance or creating "liquid short-circuit" channels. This design, combined with the microchannel network of the downstream ASD-003 resin particles, maximizes the contact efficiency between the liquid and the adsorption active sites, significantly improving pollutant removal rates.

[0028] Furthermore, a discharge filter plate is fixedly connected inside the resin container; the discharge filter plate is a plate-shaped member with several through holes thereon; the discharge filter plate is located below the resin layer; the edge contour of the discharge filter plate is the same as the cross-sectional shape of the inner wall of the resin container.

[0029] The discharge filter plate is designed as a single plate with several through holes, serving as a final mechanical barrier for the effluent, preventing even trace amounts of resin particles from entering the downstream system or causing pump wear. The plate is made of acid-resistant stainless steel or reinforced polypropylene, and the through-hole size should match the size of the resin particles to maintain unobstructed flow while also providing particle screening. Sealing rings or gaskets are used at the connection points with downstream pipelines to ensure a tight seal and prevent leakage.

[0030] Furthermore, liquid level sensors are respectively installed in the first resin column and the second resin column.

[0031] The liquid level sensor is used to monitor the liquid level inside the resin column in real time, and the PLC system performs data acquisition and action logic judgment. For example, when the by-product hydrochloric acid level exceeds a set height above the resin layer, it indicates that the resin has been completely wetted and is ready for adsorption. At this time, the discharge valve can be automatically opened to enter the next processing stage. The liquid level sensor is an acid-resistant capacitive or ultrasonic level gauge, which features high sensitivity, stable signal, and strong anti-interference ability, making it suitable for use in complex chemical plant conditions.

[0032] Furthermore, the lower ends of the first resin column and the second resin column are respectively provided with backwash inlets, and the upper circumferential surfaces are respectively provided with backwash outlets, which are located at the upper end of the resin layer.

[0033] The backwash outlet and backwash inlet of the first and second resin columns are connected to the backwash system.

[0034] The backwash inlet and outlet are designed to enable online cleaning of the resin column, preventing the accumulation of impurities in the resin after adsorption saturation, which would lead to a decrease in adsorption performance. Backwash water enters from the bottom in reverse direction, flowing upwards through the resin layer, flushing impurities and organic residues carried by the adsorption particles to the top outlet for discharge. The direction of the backwash water flow is opposite to the normal adsorption flow, creating a "fluid disturbance + gravity stratification" effect, maximizing impurity desorption and resin regeneration.

[0035] Furthermore, the aforementioned backwashing system includes:

[0036] A backwash pump connected to the backwash water source; the pumping direction of the backwash pump is opposite to that of the hydrochloric acid pump; a solenoid valve is provided at the inlet of the backwash pump.

[0037] One end is connected to the backwash inlet of the second resin column, and the other end is connected to the backwash water inlet of the backwash pump.

[0038] A backwash lift pipe is connected at one end to the backwash outlet of the second resin column and at the other end to the backwash inlet of the first resin column; a solenoid valve is provided at the connection between the backwash lift pipe and the first and second resin columns respectively.

[0039] A backwash outlet pipe is connected at one end to the backwash outlet of the first resin column; a solenoid valve is installed on the backwash outlet pipe.

[0040] An online COD monitor is installed on the backwash outlet pipe.

[0041] The backwashing system enables automatic backwashing circulation of the resin column after adsorption saturation. The backwash pump, controlled by a PLC system, starts at a set threshold to complete the reverse water circulation. The backwash water inlet pipe, backwash riser pipe, and backwash outlet pipe together form a closed loop, ensuring cleaning efficiency and a clear path for impurity discharge. An online COD monitor is used to monitor the organic matter concentration in the backwash water in real time. When the COD value is below a set threshold (e.g., ≤50mg / L), backwashing is complete, and the system automatically switches back to adsorption mode, improving automation and reducing the risk of human intervention and misoperation.

[0042] Furthermore, the backwash water source for the aforementioned backwash pump is a backwash water tank; the aforementioned backwash pump is connected to the backwash water tank via a pipe, the end of which extends into the bottom of the backwash water tank.

[0043] The backwash water tank, serving as the storage unit for backwash water, is designed to meet the water consumption required for a complete backwash of the system, with a 30% reserve capacity to handle temporary emergencies. This tank is located above ground or underground and connected to the backwash pump's suction port via piping, ensuring a stable water supply when the pump starts. The backwash water can be purchased pure water or recycled water, and it must be ensured that no additional ionic impurities or oil contaminants are introduced to avoid affecting resin performance.

[0044] Furthermore, the end of the backwash outlet pipe that is not connected to the first resin column is connected to the backwash water tank, and the end of the backwash outlet pipe is located at the top of the backwash water tank; a second COD online monitoring instrument is installed inside the backwash water tank.

[0045] The backwash outlet pipe is connected to the top of the backwash water tank, forming a return path for the backwash water. During the recycling of the backwash water, the water quality is continuously monitored by a second online COD monitor. Once the COD value exceeds the standard, the system will automatically discharge some of the high-concentration backwash wastewater and replenish it with fresh water to maintain stable circulating water quality and ensure the backwashing and regeneration effect on the resin. This closed-loop system design not only reduces wastewater discharge but also significantly reduces water costs for production operations, aligning with current energy conservation, emission reduction, and green production policies.

[0046] The beneficial effects of this invention are as follows: Its reasonable structural design, combined with resin adsorption, automated control, and cyclic backwashing technologies, achieves efficient removal of ferric ions, sulfate ions, and organic impurities from by-product hydrochloric acid, significantly improving the color and purity of the hydrochloric acid and enhancing its reuse value. The device, through the installation of two-stage resin columns and the intelligent control of valves and pumps using a PLC system, can automatically switch the adsorption process and determine resin saturation based on liquid level and solution clarity, avoiding manual intervention and improving system stability and continuous operation. Simultaneously, the online COD detection device for backwash water enables automatic judgment and control of the backwashing effect, ensuring thorough backwashing and water conservation. Compared to traditional methods relying on chemical precipitation, this device avoids the problems of reagent addition and secondary pollution, simplifies the operation process, and reduces operating costs. It is particularly suitable for the green treatment and resource recovery of by-product hydrochloric acid in phosgenation reactors, possessing significant industrial application value and promising prospects for promotion. Attached Figure Description

[0047] Figure 1 : A three-dimensional structural schematic diagram of Example 1;

[0048] Figure 2 Cross-sectional view of Example 1;

[0049] Figure 3 Schematic diagram of liquid flow direction in Example 1;

[0050] Figure 4 : A three-dimensional sectional view of the first resin column of this utility model;

[0051] Figure 5 : A three-dimensional structural schematic diagram of Example 2;

[0052] Figure 6 Cross-sectional view of Example 2;

[0053] Figure 7 Schematic diagram of liquid flow direction in Example 2;

[0054] Figure 8 : A three-dimensional structural schematic diagram of Example 3;

[0055] Figure 9 Cross-sectional view of Example 3;

[0056] Figure 10 Schematic diagram of liquid flow direction in Example 4;

[0057] In the diagram: 1-First resin column, 2-Second resin column, 3-Infeed pipe, 4-Lifting pipe, 5-Discharge pipe, 6-Hydrochloric acid pump, 7-Y-type filter, 8-Backwashing system, 11-Resin container, 12-Resin layer, 13-Fixing mesh, 14-Liquid distributor, 15-Discharge filter plate, 16-Level sensor, 81-Backwash pump, 82-Backwash water inlet pipe, 83-Backwash lifting pipe, 84-Backwash water outlet pipe, 85-COD online monitor, 86-Backwash water tank, 87-Second COD online monitor. Detailed Implementation

[0058] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0059] Example 1: As Figure 1-4 As shown, a filtration device for hydrochloric acid byproduct of phosgenation includes a first resin column 1 and a second resin column 2. The first resin column 1 and the second resin column 2 have the same structure. The main body is a container with resin inside, with an inlet at the top and an outlet on the circumferential surface at the bottom.

[0060] The feed inlet of the first resin column 1 is connected to the feed pipe 3. The feed pipe 3 is equipped with a solenoid valve, a Y-type filter 7 and a hydrochloric acid pump 6 in sequence from the material inlet direction. A solenoid valve is provided at the connection between the feed pipe 3 and the feed inlet of the first resin column 1.

[0061] The pumping direction of the hydrochloric acid pump 6 is from the incoming material direction to the first resin column 1;

[0062] The second resin column 2 is connected to the first resin column 1 via a lifting pipe 4; one end of the lifting pipe 4 is connected to the outlet of the first resin column 1, and the other end is connected to the inlet of the second resin column 2; the lifting pipe 4 is equipped with solenoid valves at the connection points with the first resin column 1 and the second resin column 2 respectively.

[0063] The outlet of the second resin column 2 is connected to the discharge pipe 5, and a solenoid valve is installed on the discharge pipe 5.

[0064] The first resin column 1 and the second resin column 2 are structurally symmetrical, both using vertically arranged cylindrical containers, which facilitates stable resin layer distribution and uniform liquid flow. This symmetrical design ensures the repeatability and process continuity of operations such as resin filling, replacement, and backwashing. The two resin columns are arranged in series and connected by a lift pipe 4, thereby achieving efficient and synergistic removal of ionic and organic pollutants sequentially.

[0065] The ASD-003 resin filled in the first resin column 1 is a strongly acidic cation exchange resin, mainly composed of sulfonated styrene-divinylbenzene copolymer, often existing in sodium form. ASD-003 exhibits excellent ion exchange capacity, showing high selectivity for ferric ions, ferrous ions, calcium ions, magnesium ions, and other metal ions, and can operate stably under strongly acidic conditions, making it suitable for the typical low pH environment of byproduct hydrochloric acid. The pore size and specific surface area of ​​this resin are optimized to ensure a synergistic removal effect on sulfate ions through charge shielding and weak complexation mechanisms.

[0066] The ASD-100 resin filled in the second resin column 2 is a macroporous adsorption resin. Its framework material is a styrene-divinylbenzene crosslinked copolymer with a pore size ranging from 100 to 1000 nm. Its surface is hydrophobically modified, exhibiting significant adsorption affinity for organic molecules. ASD-100 is particularly suitable for adsorbing low-polarity or neutral organic compounds such as benzene, alkanes, and aromatic amines, including aniline, toluene, and benzene. These impurities are often the root cause of the yellowing color of the byproduct hydrochloric acid. Its macroporous structure allows it to accommodate higher molecular weight organic pollutants while avoiding clogging and possessing good regeneration performance.

[0067] By sequentially configuring two functionally complementary resins, ASD-003 and ASD-100, the simultaneous removal of ionic and organic impurities can be achieved in a one-step process without introducing any chemical agents, forming the core innovative combination of this utility model.

[0068] Furthermore, the aforementioned first resin column 1 includes:

[0069] A resin container 11 in the form of a can;

[0070] A resin layer 12 is fixedly connected inside the resin container 11, radially filling the container, and having space between the upper and lower ends of the resin container 11 respectively.

[0071] The outlet of the first resin column 1 or the second resin column 2 is located at the lower end of the resin layer 12.

[0072] The resin container 11 is made of pressure-bearing structural material, such as acid-resistant fiberglass, fluoropolymer-lined steel, or polypropylene, capable of withstanding the chemical and physical loads from continuous acidic liquid operation. The resin layer 12 fills the interior of the container without occupying the top and bottom space, allowing for sufficient liquid distribution and uniform flow throughout the entire resin bed. The height-to-diameter ratio of the resin bed is controlled at 4:1, a result optimized by combining adsorption kinetics, pressure drop stability, and backwashing efficiency, effectively preventing resin compaction and channel effects.

[0073] For ASD-003 resin, maintaining a high aspect ratio of 4:1 ensures that its ion exchange layer has sufficient thickness to handle high concentrations of iron ions and sulfate impurities without saturating too quickly. Simultaneously, maintaining an appropriate flow rate (10 BV / h) balances contact time and throughput, meeting the needs of continuous industrial operation. Similarly, ASD-100 requires controlling bed thickness while maintaining a certain degree of fluid distribution uniformity to ensure sufficient adsorption of organic matter and prevent breakthrough.

[0074] Furthermore, a fixing mesh 13 is respectively provided on the upper and lower end faces of the resin layer 12; the fixing mesh 13 is fixedly connected to the inner wall of the resin container 11; the outer edge contour of the fixing mesh 13 is the same as the cross-section of the resin layer 12.

[0075] The design of the fixed mesh 13 is to prevent the resin layer 12 from floating or migrating during liquid flow impact or backwashing, ensuring that the resin remains stably in its effective adsorption position. The mesh material must possess acid resistance and structural stability, and is made of polypropylene fiber or fluorinated stainless steel wire mesh. Its pore size is designed to be smaller than the resin particle size (typically 300-500μm), thereby effectively preventing resin particles from being lost with the liquid flow. The mesh is secured to the inner wall of the resin container 11 by welding or flange clamping to enhance structural stability and ensure no detachment during long-term operation.

[0076] Furthermore, a liquid distributor 14 is fixed inside the resin container 11; the liquid distributor 14 is located at the upper end of the resin layer 12 and the lower end of the inlet.

[0077] The liquid distributor 14 is located above the resin layer 12. Through a multi-point outlet or a uniformly distributed circumferential perforation design, it ensures that the byproduct hydrochloric acid entering the resin column is evenly distributed vertically throughout the entire bed, preventing single-point impacts from causing resin disturbance or forming "liquid short-circuit" channels. This design, combined with the micro-channel network of the downstream ASD-003 resin particles, maximizes the contact efficiency between the liquid and the adsorption active sites, significantly improving the pollutant removal rate.

[0078] Furthermore, a discharge filter plate 15 is fixedly connected inside the resin container 11; the discharge filter plate 15 is a plate-shaped member with several through holes thereon; the discharge filter plate 15 is located below the resin layer 12; the edge contour of the discharge filter plate 15 is the same as the cross-sectional shape of the inner wall of the resin container 11.

[0079] The discharge filter plate 15 is designed as a plate-like component with several through holes, used for final mechanical blocking of the effluent to prevent even a small amount of resin particles from entering the downstream system or causing pump wear. The plate is made of acid-resistant stainless steel or reinforced polypropylene, and the through hole size should match the size of the resin particles to maintain unobstructed liquid flow while providing particle screening functionality. Sealing rings or gaskets are used at the connection points with downstream pipelines to ensure a tight seal and prevent leakage.

[0080] This embodiment relates to a resin purification system for by-product hydrochloric acid, including a first resin column 1 and a second resin column 2. The first resin column 1 is filled with ASD-003 strong acid cation exchange resin to remove metal ions, calcium and magnesium hardness, and some impurities from the by-product hydrochloric acid; the second resin column 2 is filled with ASD-100 macroporous adsorption resin to further adsorb organic impurities, color, and trace metal impurities from the by-product hydrochloric acid, thereby improving the purity and appearance of the acid solution.

[0081] The by-product hydrochloric acid is first pumped to the top of the first resin column 1, and then evenly distributed into the resin bed via a distributor. When the level sensor detects that the liquid level in the first resin column 1 has overflowed the top of the resin layer, the PLC control system automatically performs the following operations:

[0082] Open the hydrochloric acid outlet valve of the first resin column 1;

[0083] At the same time, open the hydrochloric acid inlet valve of the second resin column 2.

[0084] The byproduct hydrochloric acid enters the second resin column 2 from the first resin column 1 for further purification. When the level sensor 16 detects that the liquid level in the second resin column 2 has overflowed the resin layer, the PLC control system automatically:

[0085] Open the hydrochloric acid outlet valve of the second resin column 2;

[0086] The purified byproduct hydrochloric acid flows into the finished acid storage tank for subsequent use.

[0087] This system achieves series multi-layer purification treatment of by-product hydrochloric acid. It has a simple structure, good purification effect, and a high degree of automation.

[0088] Example 2: Figure 5-7 As shown, based on Example 1, a liquid level sensor 16 is further provided in the first resin column 1 and the second resin column 2 respectively.

[0089] The level sensor 16 is used to monitor the liquid level inside the resin column in real time, and the PLC system performs data acquisition and action logic judgment. For example, when the by-product hydrochloric acid level exceeds the set height above the resin layer 12, it indicates that the resin has been completely wetted and is ready for adsorption. At this time, the discharge valve can be automatically opened to enter the next processing stage. The level sensor is an acid-resistant capacitive or ultrasonic level gauge, which features high sensitivity, stable signal, and strong anti-interference ability, making it suitable for use in complex chemical plant conditions.

[0090] Furthermore, the lower ends of the first resin column 1 and the second resin column 2 are respectively provided with backwash inlets, and the upper circumferential surfaces are respectively provided with backwash outlets, which are located at the upper end of the resin layer 12.

[0091] The backwash outlet and backwash inlet of the first resin column 1 and the second resin column 2 are connected to the backwash system 8.

[0092] The backwash inlet and outlet are designed to enable online cleaning of the resin column, preventing the accumulation of impurities in the resin after adsorption saturation, which would lead to a decrease in adsorption performance. Backwash water enters from the bottom in reverse direction, flowing upwards through resin layer 12, flushing impurities and organic residues carried by the adsorption particles to the top outlet for discharge. The direction of the backwash water flow is opposite to the normal adsorption flow, creating a "fluid disturbance + gravity stratification" effect, maximizing impurity desorption and resin regeneration.

[0093] Furthermore, the aforementioned backwashing system 8 includes:

[0094] A backwash pump 81 is connected to the backwash water source; the pumping direction of the backwash pump 81 is opposite to that of the hydrochloric acid pump 6; a solenoid valve is provided at the water inlet of the backwash pump 81.

[0095] One end of the backwash water inlet is connected to the backwash water inlet of the second resin column 2, and the other end is connected to the water outlet of the backwash pump 81.

[0096] A backwash lift pipe 83 is connected at one end to the backwash outlet of the second resin column 2 and at the other end to the backwash inlet of the first resin column 1; a solenoid valve is provided at the connection between the backwash lift pipe 83 and the first resin column 1 and the second resin column 2 respectively.

[0097] A backwash outlet pipe 84 is connected at one end to the backwash outlet of the first resin column 1; a solenoid valve is provided on the backwash outlet pipe 84.

[0098] A COD online monitoring instrument 85 is installed on the backwash outlet pipe 84.

[0099] The backwashing system 8 enables automatic backwashing circulation of the resin column after adsorption saturation. The backwash pump 81, controlled by the PLC system, starts according to a set threshold to complete the reverse water circulation. The backwash water inlet pipe 82, backwash riser pipe 83, and backwash outlet pipe 84 together form a closed loop, ensuring cleaning efficiency and a clear path for impurity discharge. The online COD monitor 85 monitors the concentration of organic matter in the backwash water in real time. When the COD value is lower than a set threshold (e.g., ≤50mg / L), backwashing is complete, and the system automatically switches back to adsorption mode, improving automation and reducing the risk of human intervention and misoperation.

[0100] Based on Example 1, this example further introduces intelligent control and automatic backwashing functions for the by-product hydrochloric acid purification system.

[0101] In this embodiment, the inlet and outlet valves of the first resin column 1 and the second resin column 2 are both controlled by a PLC system. The by-product hydrochloric acid purification process is the same as in Example 1.

[0102] After the system has been running for a period of time, if the liquid effluent from the second resin column 2 is no longer clear and transparent, it indicates that the resin adsorption has reached saturation. The PLC system determines that it needs to switch to backwashing mode. At this time, the PLC system automatically executes the following control logic:

[0103] Stop hydrochloric acid pump 6;

[0104] Close all hydrochloric acid inlet and outlet valves of the first resin column 1 and the second resin column 2;

[0105] Start backwash pump 81;

[0106] Open the backwash water inlet valve and the backwash water outlet valve.

[0107] The backwash water is delivered to the bottom of the resin column by the backwash pump 81, passes through the resin layer from bottom to top, carries out the adsorbed impurities, and is discharged from the backwash outlet pipe 84.

[0108] The system is equipped with an online COD concentration monitoring device 85 to monitor the pollution level of the backwash effluent in real time. When the COD value remains higher than the set threshold, the system continues backwashing; once the COD concentration drops to the set value (e.g., below 50 mg / L), indicating that the resin has been cleaned, the PLC system automatically executes:

[0109] Close the backwash pump and backwash valve;

[0110] Start hydrochloric acid pump 6;

[0111] Open the hydrochloric acid inlet and outlet valves of the first and second resin columns;

[0112] The system has resumed its normal purification process.

[0113] Through the above-described electrical control logic, this embodiment realizes intelligent control and automatic backwashing of the entire process of the by-product hydrochloric acid purification system, effectively improving the system's operating efficiency and stability.

[0114] Example 3: As Figure 8-10 As shown, based on Example 2, the backwash water source of the backwash pump 81 is the backwash water tank 86; the backwash pump 81 is connected to the backwash water tank 86 through a pipe, the end of which extends into the bottom of the backwash water tank 86.

[0115] The backwash water tank 86 serves as the storage unit for backwash water. Its volume is designed to meet the water consumption required for a complete backwash of the system, with a 30% reserve capacity to handle temporary emergencies. This tank is located above ground or underground and is connected to the suction port of the backwash pump 81 via piping, ensuring a stable water supply when the pump starts. The backwash water can be purchased pure water or recycled water, and it must be ensured that no additional ionic impurities or oil contaminants are introduced to avoid affecting the resin performance.

[0116] Furthermore, the end of the backwash outlet pipe 84 that is not connected to the first resin column 1 is connected to the backwash water tank 86, and the end of the backwash outlet pipe 84 is located at the top of the backwash water tank 86; a second COD online monitoring instrument 87 is installed inside the backwash water tank 86.

[0117] The backwash outlet pipe 84 is connected to the top of the backwash water tank 86, forming a return path for the backwash water. During the recycling of the backwash water, the water quality is continuously monitored by a second online COD monitor 87. Once the COD value exceeds the standard, the system will automatically discharge some of the high-concentration backwash wastewater and replenish it with fresh water to maintain stable circulating water quality and ensure the backwashing and regeneration effect on the resin. This closed-loop system design not only reduces wastewater discharge but also significantly reduces water costs for production and operation, aligning with current energy conservation, emission reduction, and green production policies.

[0118] Based on Example 2, this example introduces a backwash water recycling system.

[0119] The system is equipped with a backwash water tank 86. The backwash pump 81 draws water from the backwash water tank 86 and delivers it to the bottom of the resin column through the backwash water inlet pipe 82 to complete the backwash process. The backwash water is discharged through the backwash water outlet pipe 84 and monitored by a second online COD analyzer 87.

[0120] When the COD value of the backwash effluent is lower than the set reuse threshold (e.g., 60 mg / L), the backwash effluent is allowed to flow back to the backwash water tank 86 through the three-way valve.

[0121] When the COD value is higher than the set emission threshold (e.g., 80 mg / L), the backwash effluent is discharged into the sewage treatment system.

[0122] The system is also equipped with an external water replenishment device, which automatically replenishes fresh water when the water level in the backwash tank 86 falls below the lower limit, ensuring the continuity of backwashing.

[0123] Similarly, when a decrease in the transparency of the liquid exiting the second resin column 2 is detected, the PLC system will automatically:

[0124] Stop hydrochloric acid pump 6;

[0125] Close the hydrochloric acid inlet and outlet valves of the resin column;

[0126] Start backwash pump 81 to perform backwashing;

[0127] Determine whether to reuse backwash effluent based on COD value;

[0128] Once the COD level stabilizes and meets the requirements, the backwashing device will automatically shut down and the hydrochloric acid treatment process will resume.

[0129] This embodiment has good water resource recycling capabilities, effectively reduces operating costs, and improves environmental performance.

[0130] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A filtration device for hydrochloric acid, a byproduct of phosgenation, comprising a first resin column (1) and a second resin column (2), characterized in that: The first resin column (1) and the second resin column (2) have the same structure. The main body is a container with resin inside, with an inlet at the top and an outlet on the circumferential surface at the bottom. The feed inlet of the first resin column (1) is connected to the feed pipe (3). The feed pipe (3) is equipped with a solenoid valve, a Y-type filter (7) and a hydrochloric acid pump (6) in sequence from the material inlet direction. A solenoid valve is provided at the connection between the feed pipe (3) and the feed inlet of the first resin column (1). The hydrochloric acid pump (6) pumps material from the incoming material direction to the first resin column (1). The second resin column (2) is connected to the first resin column (1) through a lifting pipe (4); one end of the lifting pipe (4) is connected to the outlet of the first resin column (1), and the other end is connected to the inlet of the second resin column (2); the lifting pipe (4) is equipped with solenoid valves at the connection points with the first resin column (1) and the second resin column (2). The outlet of the second resin column (2) is connected to the discharge pipe (5), and a solenoid valve is installed on the discharge pipe (5).

2. The filtration device for hydrochloric acid byproduct of phosgenation according to claim 1, characterized in that: The first resin column (1) comprises: A resin container in the form of a can (11); A resin layer (12) is fixedly connected inside the resin container (11), radially filling the container, and has space between the upper and lower ends of the resin container (11). The outlet of the first resin column (1) or the second resin column (2) is located at the lower end of the resin layer (12).

3. The filtration device for hydrochloric acid byproduct of phosgenation according to claim 2, characterized in that: Fixed mesh (13) is provided on the upper and lower end faces of the resin layer (12); the fixed mesh (13) is fixedly connected to the inner wall of the resin container (11); the outer edge contour of the fixed mesh (13) is the same as the cross-section of the resin layer (12).

4. A filtration device for hydrochloric acid, a byproduct of phosgenation, according to claim 2, characterized in that: A liquid distributor (14) is fixed inside the resin container (11); the liquid distributor (14) is located at the upper end of the resin layer (12) and the lower end of the feed inlet.

5. A filtration device for hydrochloric acid, a byproduct of phosgenation, according to claim 2, characterized in that: The resin container (11) is fixedly connected to a discharge filter plate (15); the discharge filter plate (15) is a plate-shaped piece with several through holes thereon; the discharge filter plate (15) is located below the resin layer (12); the edge contour of the discharge filter plate (15) is the same as the cross-sectional shape of the inner wall of the resin container (11).

6. A filtration device for hydrochloric acid byproduct of phosgenation according to any one of claims 2-5, characterized in that: Liquid level sensors (16) are respectively installed in the first resin column (1) and the second resin column (2).

7. A filtration device for hydrochloric acid, a byproduct of phosgenation, according to claim 6, characterized in that: The first resin column (1) and the second resin column (2) are respectively provided with backwash inlets at their lower ends and backwash outlets on their upper circumferential surfaces. The backwash outlets are located at the upper end of the resin layer (12). The backwash outlet and backwash inlet of the first resin column (1) and the second resin column (2) are connected to the backwash system (8).

8. A filtration device for hydrochloric acid byproduct of phosgenation according to claim 7, characterized in that: The backwashing system (8) includes: A backwash pump (81) is connected to the backwash water source; the pumping direction of the backwash pump (81) is opposite to that of the hydrochloric acid pump (6); a solenoid valve is provided at the water inlet of the backwash pump (81). One end is connected to the backwash inlet of the second resin column (2), and the other end is connected to the backwash water inlet pipe (82) of the backwash pump (81). A backwashing lift pipe (83) is connected at one end to the backwash outlet of the second resin column (2) and at the other end to the backwash inlet of the first resin column (1); a solenoid valve is provided at the connection between the backwashing lift pipe (83) and the first resin column (1) and the second resin column (2). A backwash outlet pipe (84) is connected at one end to the backwash outlet of the first resin column (1); a solenoid valve is provided on the backwash outlet pipe (84); A COD online monitoring instrument (85) is installed on the backwash outlet pipe (84).

9. A filtration device for hydrochloric acid, a byproduct of phosgenation, according to claim 8, characterized in that: The backwash water source of the backwash pump (81) is the backwash water tank (86); the backwash pump (81) is connected to the backwash water tank (86) through a pipe, the end of which extends into the bottom of the backwash water tank (86).

10. A filtration device for hydrochloric acid, a byproduct of phosgenation, according to claim 9, characterized in that: The end of the backwash outlet pipe (84) that is not connected to the first resin column (1) is connected to the backwash water tank (86), and the end of the backwash outlet pipe (84) is located at the top of the backwash water tank (86); a second COD online monitoring instrument (87) is installed inside the backwash water tank (86).

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