A phosgene recovery device
By designing a phosgene recovery device and utilizing a combination of a buffer tank and a falling film absorption tower, the phosgene in the exhaust gas was cooled, dissolved, and recovered in stages, solving the problem of phosgene waste and realizing the reuse of phosgene and energy conservation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANDONG CHONGSHUN NEW MATERIAL TECH CO LTD
- Filing Date
- 2025-06-12
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, excess phosgene in the phosgenation reaction is not recovered and utilized, resulting in waste and increased post-processing burden, which affects economic efficiency.
A phosgene recovery device was designed, including a spray device and a buffer tank with a gas dispersion plate. By combining the buffer tank, falling film absorption tower and receiving vessel, the phosgene in the tail gas is gradually cooled and dissolved by a low-temperature solvent, and then recovered and reused.
This achieves efficient recovery and reuse of phosgene, thus achieving the goal of energy conservation and consumption reduction, and reducing the burden of catalyst use and post-processing.
Smart Images
Figure CN224270695U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of chemical equipment technology, specifically to a phosgene recovery device. Background Technology
[0002] Phosgenation reactions have wide applications in chemical production processes, such as the synthesis of 1,5-naphthalene diisocyanate (NDI). Currently, phosgenation reactions mainly involve the reaction of the main raw material with phosgene (gaseous) or di(trichloromethyl) carbonate (commonly known as solid phosgene). To improve the conversion rate of the main raw material, it is often necessary to increase the proportion of phosgene or solid phosgene to an excess, resulting in some phosgene still being discharged with the reaction tail gas. The current common method for treating this tail gas is to first decompose it by contact with a catalyst, then wash it with water circulation, and finally neutralize it with alkali. This treatment method not only wastes phosgene but also requires a large amount of catalyst, increasing the burden of post-treatment and seriously affecting economic efficiency. Summary of the Invention
[0003] The technical problem to be solved by this utility model is to provide a phosgene recovery device that overcomes the defects of the prior art and can recover and reuse the excess phosgene used in production, thereby achieving the purpose of energy conservation and emission reduction.
[0004] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:
[0005] A phosgene recovery device includes a buffer tank equipped with a spray device and a gas dispersion plate. The top of the buffer tank has a chlorobenzene inlet and a gas outlet, and the bottom has a liquid outlet. A gas inlet is provided at the connection of the gas dispersion plate on the side wall of the buffer tank. The chlorobenzene inlet of the buffer tank is connected to a solvent replenishment tank through pipes and valves. The gas outlet and liquid outlet of the buffer tank are respectively connected to the feed inlet of a falling film absorber through pipes and valves. The liquid outlet of the falling film absorber is connected to the liquid inlet of a receiving vessel through pipes and valves. The gas outlet of the falling film absorber is connected to the gas inlet of the receiving vessel through pipes and valves. The liquid inlet of the receiving vessel is also connected to a chlorobenzene storage tank through pipes and valves. The liquid outlet of the receiving vessel is connected to the solvent replenishment tank, the falling film absorber, and the reaction vessel (for reuse of the recovered phosgene) through pipes, valves, and a pump.
[0006] Preferably, the spraying device is located in the upper part of the cavity of the buffer tank and is connected to the chlorobenzene inlet of the buffer tank through a pipeline.
[0007] Preferably, the gas dispersion disc is located in the lower part of the buffer tank cavity and is screwed to the side wall of the buffer tank (the dispersion disc is immersed in the solvent, and there is a 2-5cm gap between the outer edge and the buffer tank, so it can be removed for replacement and maintenance; the gas pipe, the outer wall of the buffer tank, and the gas inlet of the gas dispersion disc are connected by screws); the gas inlet of the gas dispersion disc is connected to the exhaust gas input device through a pipe passing through the gas inlet of the side wall of the buffer tank; the gas dispersion disc is a disc-shaped structure composed of spirally arranged pipes, and the upper part of the pipes of the gas dispersion disc is provided with several gas outlet holes, and there are gaps between the spirally arranged pipes (to facilitate liquid dripping to the bottom of the tank).
[0008] Preferably, the falling film absorption tower is equipped with a temperature exchange device; the inlet and outlet of the temperature exchange device are respectively connected to a chilled water supply device and a chilled water collection device.
[0009] Preferably, the falling film absorption tower is model YKCX-30.
[0010] Preferably, the receiving vessel is an enamel-lined vessel equipped with a temperature exchange device; the inlet and outlet of the temperature exchange device are respectively connected to a chilled water supply device and a chilled water collection device.
[0011] Preferably, the receiving vessel is provided with an exhaust gas outlet at the top, and the exhaust gas outlet is connected to the exhaust gas treatment device through a pipeline.
[0012] Preferably, the pump connected to the liquid outlet of the receiving vessel via a pipeline is a circulating pump (fluoropolymer-lined magnetic pump); the model of the circulating pump is CQF50-32-125.
[0013] Due to the adoption of the above technical solution, the beneficial effects of this utility model are:
[0014] This invention utilizes the low boiling point and easy solubility of phosgene in chlorobenzene. First, the gas is cooled and the phosgene in the tail gas is initially dissolved using a gas dispersion plate and spray device (with low-temperature solvent added from the receiving vessel) in a buffer tank. Then, the dissolved liquid and tail gas are transported together to a low-temperature falling film absorption tower for further cooling and absorption. Finally, the tail gas and dissolved liquid are transported together to the receiving vessel. The unabsorbed gas is transported to the tail gas treatment device, and the absorbed phosgene and solvent are transported together to the production workshop for reuse. Part of the solvent is transported to the solvent replenishment tank for initial dissolution of tail gas or to the falling film absorption tower for phosgene dissolution.
[0015] In summary, this invention can effectively recover and reuse excess phosgene in production, achieving the goal of energy conservation and consumption reduction. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the device structure according to an embodiment of the present utility model;
[0017] In the diagram, 1 is a spray device; 2 is a gas dispersion plate; 3 is a buffer tank; 4 is a solvent replenishment tank; 5 is a falling film absorption tower; 6 is a receiving vessel; and 7 is a chlorobenzene storage tank. Detailed Implementation
[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0019] like Figure 1 As shown, a phosgene recovery device includes a buffer tank 3 equipped with a spray device 1 and a gas dispersion plate 2. The top of the buffer tank 3 is provided with a chlorobenzene inlet (not shown) and a gas outlet (not shown), and the bottom is provided with a liquid outlet (not shown). A gas inlet (not shown) is provided at the connection of the gas dispersion plate 2 on the side wall of the buffer tank 3. The chlorobenzene inlet of the buffer tank 3 is connected to a solvent replenishment tank 4 through a pipe (not shown) and a valve (not shown). The gas outlet and liquid outlet of the buffer tank 3 are connected to the feed inlet of a falling film absorption tower 5 through pipes and valves, respectively. The liquid outlet of the falling film absorption tower 5 is connected to the liquid inlet of a receiving vessel 6 through pipes and valves. The gas outlet of the falling film absorption tower 5 is connected to the gas inlet of the receiving vessel 6 through pipes and valves. The liquid inlet of the receiving vessel 6 is also connected to a chlorobenzene storage tank 7 through pipes and valves. The liquid outlet of the receiving vessel 6 is connected to the solvent replenishment tank 4, the falling film absorption tower 5, and the reaction vessel (not shown) through pipes, valves, and a circulation pump (not shown), respectively.
[0020] In actual production, a certain amount of chlorobenzene solvent is first injected into the receiving vessel 6, and the solvent is cooled to about -5 to 5°C by chilled water. The circulation pump is started to transport part of the low-temperature solvent to the buffer tank 3 and the falling film absorption tower 5. The temperature exchange device of the falling film absorption tower 5 is turned on and the chilled water is used for cooling.
[0021] The exhaust gas generated during production enters the buffer tank 3 through a conveying pipeline. After being dispersed by the gas dispersion plate 2, it is diffused in the buffer tank 3. After being cooled and initially dissolved by the solvent sprayed by the spray device 1, the exhaust gas and the dissolved liquid are transported together to the falling film absorption tower 5 for further cooling and dissolution. Then, the dissolved liquid is transported to the receiving vessel 6. The exhaust gas (containing a small amount of phosgene that has not been cooled and dissolved) is transferred in the receiving vessel and then enters the exhaust gas treatment system through a pipeline. In this way, by cooling and dissolving the exhaust gas in stages, the phosgene in the exhaust gas can be effectively recovered into the solvent. The remaining exhaust gas is then treated by the exhaust gas treatment device. The recovered phosgene is then transported to the workshop for continued use. Because phosgene also requires low-temperature solvent absorption and stirring reaction with the main material during normal use, and the key reaction process also includes low-temperature reaction, the recovered phosgene solution can be used directly. The phosgene content can be calculated according to theory and production experience, or a sample can be taken to test its content to determine whether it needs to be added during production and how much to add. If solvent needs to be replenished, the required solvent is added from chlorobenzene storage tank 7 to continue phosgene recovery.
[0022] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
Claims
1. A phosgene recovery device, characterized in that: The system includes a buffer tank equipped with a spray device and a gas dispersion plate. The top of the buffer tank has a chlorobenzene inlet and a gas outlet, and the bottom has a liquid outlet. A gas inlet is located at the connection point of the gas dispersion plate on the side wall of the buffer tank. The chlorobenzene inlet of the buffer tank is connected to a solvent replenishment tank via pipes and valves. The gas outlet and liquid outlet of the buffer tank are connected to the feed inlet of a falling film absorption tower via pipes and valves, respectively. The liquid outlet of the falling film absorption tower is connected to the liquid inlet of a receiving vessel via pipes and valves. The gas outlet of the falling film absorption tower is connected to the gas inlet of the receiving vessel via pipes and valves. The liquid inlet of the receiving vessel is also connected to a chlorobenzene storage tank via pipes and valves. The liquid outlet of the receiving vessel is connected to the solvent replenishment tank, the falling film absorption tower, and the reaction vessel via pipes, valves, and a pump, respectively.
2. The phosgene recovery device as described in claim 1, characterized in that: The spraying device is located in the upper part of the cavity of the buffer tank and is connected to the chlorobenzene inlet of the buffer tank through a pipeline.
3. The phosgene recovery device as described in claim 1, characterized in that: The gas dispersion disc is located in the lower part of the cavity of the buffer tank and is screwed to the side wall of the buffer tank; the gas inlet of the gas dispersion disc is connected to the exhaust gas input device through a pipe passing through the gas inlet of the side wall of the buffer tank; the gas dispersion disc is a disc-shaped structure composed of spirally arranged pipes, and the upper part of the pipes of the gas dispersion disc is provided with several gas outlet holes, and there are gaps between the spirally arranged pipes.
4. The phosgene recovery device as described in claim 1, characterized in that: Both the falling film absorption tower and the receiving vessel are equipped with temperature exchange devices.
5. The phosgene recovery device as described in claim 1, characterized in that: The receiving vessel is an enamel-lined vessel.
6. The phosgene recovery device as described in claim 1, characterized in that: The receiving vessel is equipped with a tail gas outlet at the top, which is connected to the tail gas treatment device via a pipeline.