Solvent recovery phosgene system in production process of 1, 5-pentamethylene diisocyanate
By designing a solvent recovery phosgene system including phosgene absorption tower and intermediate tank, the problems of complex operation and high equipment costs of existing processes are solved, and efficient recycling and industrial application of phosgene are achieved.
Patent Information
- Application Number
- CN202421060962.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-16
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2034-05-16
AI Technical Summary
The existing solvent recovery phosgene process is complicated to operate, resulting in high equipment costs and is not conducive to large-scale industrialization.
A solvent recovery phosgene system including a phosgene absorption tower, an intermediate tank, a machine pump, a condenser and a gas-liquid separation tank is designed. The phosgene concentration of the absorbed liquid is monitored by a concentration meter, and the absorbed liquid is transported to the phosgeneization reaction device through a machine pump for recycling.
It realizes efficient recycling and utilization of phosgene, reduces production costs, is simple in operation, and is suitable for large-scale industrial production.
Smart Images
Figure CN222943213U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of solvent recovery of phosgene, in particular to a solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate. Background Art
[0002] 1,5-Pentamethylene diisocyanate (PDI) is a new type of aliphatic isocyanate with yellowing resistance. It is usually made into PDI biuret or trimer for the manufacture of polyurethane coatings, inks and artificial leather.
[0003] At present, PDI is usually synthesized by gas phase phosgenation. In the synthesis, o-dichlorobenzene is used as the solvent. Phosgene participates in the reaction in excess. A large amount of phosgene needs to be recovered and reused. Most factories usually use a solvent recovery phosgene process. This process includes two stages, absorption and desorption. In actual operation, it will have the following adverse effects: on the one hand, the recovery of these phosgenes requires not only an absorption tower but also a desorption tower, which leads to an increase in the overall equipment cost; on the other hand, the process operation is complicated and is not conducive to large-scale industrialization. Therefore, it is urgent to develop a simple and practical solvent recovery phosgene system. Summary of the invention
[0004] The utility model aims to overcome the defects of the prior art and provide a solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate.
[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the utility model is: a solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate, comprising a phosgene absorption tower, the phosgene absorption tower is filled with fillers, and is characterized in that: the gas phase inlet of the phosgene absorption tower kettle is connected to the first gas phase pipe, the liquid phase outlet of the phosgene absorption tower kettle is connected to the intermediate tank through the first liquid phase pipe, the liquid phase inlet at the top of the intermediate tank is connected to the second liquid phase pipe, the liquid phase outlet at the bottom of the intermediate tank is connected to the machine pump through the third liquid phase pipe, the machine pump outlet is connected to the condenser through the fourth liquid phase pipe, the liquid phase outlet at the top of the condenser is returned to the phosgene absorption tower through the fifth liquid phase pipe, the gas phase outlet at the top of the phosgene absorption tower is connected to the gas-liquid separation tank through the second gas phase pipe, the liquid phase outlet at the bottom of the gas-liquid separation tank is returned to the phosgene absorption tower through the sixth liquid phase pipe, and the gas phase outlet at the top of the gas-liquid separation tank is connected to the tail gas absorption device through the third gas phase pipe.
[0006] The third liquid phase tube is provided with a concentration meter for measuring the phosgene concentration in the absorption liquid.
[0007] The fourth liquid phase tube is connected to a seventh liquid phase tube, and the seventh liquid phase tube is connected to a phosgenation reaction device.
[0008] The condenser is connected with the refrigerated chlorobenzene inlet and outlet pipelines.
[0009] The principle of the utility model is that phosgene participates in the reaction in excess in the synthesis of 1,5-pentanediisocyanate, and a large amount of phosgene needs to be recovered and reused, so the process flow is designed with a phosgene absorption tower. Since the solvent used in the synthesis of 1,5-pentanediisocyanate is o-dichlorobenzene, phosgene is soluble in o-dichlorobenzene, and o-dichlorobenzene has good selectivity for phosgene, o-dichlorobenzene is selected as the absorbent, phosgene is used as the solute, and the absorption process is physical absorption. A countercurrent operation method is adopted, in which the phosgene gas phase flows from bottom to top in the absorption tower, and the o-dichlorobenzene liquid phase flows from the top of the tower to the bottom of the tower, and the formed absorption liquid flows out from the bottom of the tower to the intermediate tank, and the absorption liquid in the intermediate tank is transported to a phosgenation reaction device by a machine pump for recovery and reuse.
[0010] The beneficial effects of the utility model are: the system design is highly practical, the operation process is simple, it can be used to absorb phosgene in the production process of 1,5-pentanediisocyanate, achieve efficient recovery and utilization of phosgene, and greatly reduce production costs; it is suitable for large-scale industrial production and has strong practicality and promotion in the same industry. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a schematic diagram of the utility model.
[0012] In the figure: T-phosgene absorption tower, V-intermediate tank, P-machine pump, E-condenser, S-gas-liquid separation tank, X-filler, D-concentrator, 1-first gas phase tube, 2-first liquid phase tube, 3-second liquid phase tube, 4-third liquid phase tube, 5-fourth liquid phase tube, 6-fifth liquid phase tube, 7-second gas phase tube, 8-sixth liquid phase tube, 9-third gas phase tube, 10-seventh liquid phase tube. DETAILED DESCRIPTION
[0013] The present invention is further described in detail below in conjunction with embodiments. The embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.
[0014] Example 1, see Figure 1A solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate comprises a phosgene absorption tower T, in which a filler X is filled, and characterized in that: the gas phase inlet of the bottom of the phosgene absorption tower T is connected to the first gas phase pipe 1, the liquid phase outlet of the bottom of the phosgene absorption tower T is connected to the intermediate tank V through the first liquid phase pipe 2, the liquid phase inlet at the top of the intermediate tank V is connected to the second liquid phase pipe 3, the liquid phase outlet at the bottom of the intermediate tank V is connected to the pump P through the third liquid phase pipe 4, the pump P outlet is connected to the condenser E through the fourth liquid phase pipe 5, the liquid phase outlet at the top of the condenser E is returned to the phosgene absorption tower T through the fifth liquid phase pipe 6, the gas phase outlet at the top of the phosgene absorption tower T is connected to the gas-liquid separation tank S through the second gas phase pipe 7, the liquid phase outlet at the bottom of the gas-liquid separation tank S is returned to the phosgene absorption tower T through the sixth liquid phase pipe 8, and the gas phase outlet at the top of the gas-liquid separation tank S is connected to the tail gas absorption device through the third gas phase pipe 9.
[0015] The third liquid phase tube 4 is provided with a concentration meter D for measuring the phosgene concentration in the absorption liquid.
[0016] The fourth liquid phase tube 5 is connected to a seventh liquid phase tube 10 , and the seventh liquid phase tube 10 is connected to a phosgenation reaction device.
[0017] The condenser E is connected to the refrigerated chlorobenzene inlet and outlet pipelines.
[0018] Working process: the phosgene tail gas enters from the bottom of the phosgene absorption tower T through the first gas phase pipe 1. From bottom to top in the phosgene absorption tower T, the unabsorbed small amount of phosgene tail gas (with a small amount of o-dichlorobenzene liquid) enters the gas-liquid separation tank S from the top of the phosgene absorption tower T through the second gas phase pipe 7. The o-dichlorobenzene liquid entrained by the phosgene tail gas returns from the bottom of the gas-liquid separation tank S through the sixth liquid phase pipe 8 to enter the phosgene absorption tower T for recycling. The unabsorbed small amount of phosgene tail gas enters the tail gas absorption device from the top of the gas-liquid separation tank S through the third gas phase pipe 9. The o-dichlorobenzene liquid enters the intermediate tank V through the second liquid phase pipe 3, and then enters the inlet of the pump P from the bottom of the intermediate tank V through the third liquid phase pipe 4, and then enters the condenser E from the outlet of the pump P through the fourth liquid phase pipe 5, and finally enters the phosgene absorption tower T from the top of the condenser E through the fifth liquid phase pipe 6. Phosgene releases heat during the process of dissolving in o-dichlorobenzene, causing the temperature in the system to rise, thereby affecting the absorption capacity of o-dichlorobenzene for phosgene. The condenser E is connected with the inlet and outlet pipelines of refrigerated chlorobenzene to remove the heat released during the absorption process in time. The o-dichlorobenzene liquid flows from the top of the tower to the bottom of the tower, and the formed absorption liquid enters the intermediate tank V from the bottom of the phosgene absorption tower T through the first liquid phase pipe 2. The phosgene absorption tower T continues to operate, and the reading of the concentration meter D on the third liquid phase pipe 4 is observed. When the phosgene concentration in the absorption liquid is ≥50%, the absorption liquid in the intermediate tank V is transported to the phosgenation reaction device through the seventh liquid phase pipe 10 by the pump P for recycling and reuse.
[0019] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the above embodiments without departing from the principles and spirit of the present invention, and the present invention and its scope are defined by the equivalents of the appended claims.
Claims
1. A solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate, comprising a phosgene absorption tower (T), the phosgene absorption tower (T) being filled with a filler (X), characterized in that: The gas phase inlet of the bottom of the phosgene absorption tower (T) is connected to the first gas phase pipe (1), the liquid phase outlet of the bottom of the phosgene absorption tower (T) is connected to the intermediate tank (V) through the first liquid phase pipe (2), the liquid phase inlet at the top of the intermediate tank (V) is connected to the second liquid phase pipe (3), the liquid phase outlet at the bottom of the intermediate tank (V) is connected to the pump (P) through the third liquid phase pipe (4), the pump (P) outlet is connected to the condenser (E) through the fourth liquid phase pipe (5), the liquid phase outlet at the top of the condenser (E) is returned to the phosgene absorption tower (T) through the fifth liquid phase pipe (6), the gas phase outlet at the top of the phosgene absorption tower (T) is connected to the gas-liquid separation tank (S) through the second gas phase pipe (7), the liquid phase outlet at the bottom of the gas-liquid separation tank (S) is returned to the phosgene absorption tower (T) through the sixth liquid phase pipe (8), and the gas phase outlet at the top of the gas-liquid separation tank (S) is connected to the tail gas absorption device through the third gas phase pipe (9).
2. The solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate according to claim 1, characterized in that: The third liquid phase tube (4) is provided with a concentration meter (D) for measuring the phosgene concentration in the absorption liquid.
3. The solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate according to claim 1, characterized in that: The fourth liquid phase tube (5) is connected to a seventh liquid phase tube (10), and the seventh liquid phase tube (10) is connected to a phosgenation reaction device.
4. The solvent recovery phosgene system in the production process of 1,5-pentanediisocyanate according to claim 1, characterized in that: The condenser (E) is connected to the refrigerated chlorobenzene inlet and outlet pipelines.