An apparatus for adding a catalyst in an isocyanate-based reaction

Abstract

This utility model relates to an apparatus for adding a catalyst in isocyanate reactions. Its features include: a discharge pipe on a catalyst storage tank connected to a high-level tank via an electric pump; a liquid outlet pipe connected to the bottom of the high-level tank; a first flow meter, a first regulating valve, and a first switching valve sequentially installed on the liquid outlet pipe; the first switching valve connected to a reaction vessel; another inlet on the reaction vessel connected to an amine inlet pipe via a second switching valve; and a second flow meter and a second regulating valve connected to the amine inlet pipe; the reaction vessel also has an insertion pipe for introducing phosgene or phosgene solution. The overall layout is reasonable, the equipment structure is simple and easy to manufacture, the instruments and their control logic are clear and easy to operate, enabling automatic catalyst addition, catalytic reaction rate improvement, and increased effective amine conversion rate and product yield.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, specifically relating to an apparatus for adding a catalyst in the synthesis of isocyanates, particularly an apparatus for synthesizing aliphatic isocyanates. Background Technology

[0002] Currently, the main process technology for synthesizing acyl chloride series products, chloroformate series products, monoisocyanate series products, diisocyanate series products, and polyisocyanate series products is the phosgenation method, with phosgene and amines being among the main raw materials. The byproduct HCl generated during the reaction of these two raw materials readily reacts rapidly with amines to form amino hydrochlorides. Amino hydrochlorides are relatively stable and difficult to phosgenate to form the desired isocyanate groups, resulting in an increase in byproducts throughout the reaction system. This increases the difficulty of product purification, reduces product yield, and increases production costs. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology, design a device for adding catalysts and inhibiting the reaction between hydrogen chloride and amines, and to quickly remove hydrogen chloride, thereby improving reaction efficiency and product yield.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: an apparatus for adding a catalyst in an isocyanate reaction, comprising a reaction vessel, characterized in that: a discharge pipe on a catalyst storage tank is connected to a high-level tank via an electric pump; a liquid discharge pipe is connected to the bottom of the high-level tank; a first flow meter, a first regulating valve, and a first switching valve are sequentially installed on the liquid discharge pipe; the first switching valve is connected to the reaction vessel; another inlet on the reaction vessel is connected to an amine inlet pipe via a second switching valve; a second flow meter and a second regulating valve are connected to the amine inlet pipe; the reaction vessel is also provided with an insertion pipe for introducing phosgene or phosgene solution; The second flow meter is interlocked with the first switching valve and the first regulating valve, and the first flow meter is interlocked with the first regulating valve.

[0005] The top of the high-level tank is equipped with a first exhaust pipe, and the top of the reactor is equipped with a second exhaust pipe. The second exhaust pipe is equipped with a safety valve for protecting the equipment.

[0006] The high-level tank is located 3-4m directly above the reactor to allow the catalyst to flow by gravity; a level gauge is installed on the high-level tank to measure the storage and outflow.

[0007] The reactor is equipped with a stirrer, a thermometer, a pressure gauge, and a level gauge for observing and controlling process parameters.

[0008] The beneficial effects of this utility model are: the overall layout is reasonable, the equipment structure is simple and easy to process, the instruments and their control logic are clear, the hierarchy is distinct, easy to operate and easy to process, and it can realize automatic addition of catalyst and rapid removal of hydrogen chloride. During the cold photochemical reaction of isocyanate, it isolates the by-product hydrogen chloride generated by amine from contact with amine, reduces the formation of amine hydrochloride, promotes the synthesis of aminoformyl chloride, improves the reaction rate and amine conversion rate, and improves the removal speed of hydrogen chloride. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the present invention; In the diagram: 1-Catalyst storage tank, 2-Electric pump, 3-High-level tank, 4-Outlet pipe, 5-First exhaust pipe, 6-Reaction vessel, 7-Amine inlet pipe, 8-Second exhaust pipe, 9-Insertion pipe; B1 - First flow meter, B2 - Second flow meter, D1 - First switching valve, D2 - Second switching valve, F - Safety valve, F1 - First regulating valve, F2 - Second regulating valve. Detailed Implementation

[0010] The following embodiments will further illustrate the solution provided by this utility model, but this utility model is not limited to the listed embodiments.

[0011] Example 1, see Figure 1 An apparatus for adding a catalyst in an isocyanate reaction includes a reaction vessel 6. The apparatus is characterized in that a discharge pipe on a catalyst storage tank 1 is connected to a high-level tank 3 via an electric pump 2; a liquid outlet pipe 4 is connected to the bottom of the high-level tank 3; a first flow meter B1, a first regulating valve F1, and a first switching valve D1 are sequentially installed on the liquid outlet pipe 4; the first switching valve D1 is connected to the reaction vessel 6; another inlet on the reaction vessel 6 is connected to an amine inlet pipe 7 via a second switching valve D2; a second flow meter B2 and a second regulating valve F2 are connected to the amine inlet pipe 7; and the reaction vessel 6 is also provided with an insertion pipe 9 for introducing phosgene or phosgene solution. The second flow meter B2 is interlocked with the first switching valve D1 and the first regulating valve F1, and the first flow meter B1 is interlocked with the first regulating valve F1.

[0012] The top of the high-level tank 3 is provided with a first exhaust pipe 5, and the top of the reactor 6 is provided with a second exhaust pipe 8. The second exhaust pipe 8 is provided with a safety valve F for protecting the equipment.

[0013] The high-level tank 3 is located 3-4m directly above the reactor 6 to enable the catalyst to flow by gravity; a level gauge is installed on the high-level tank 3 to measure the storage and outflow.

[0014] The reactor 6 is equipped with a stirrer, a thermometer, a pressure gauge and a level gauge for observing and controlling process parameters.

[0015] The reactor 6 is a vertical structure with a jacket or double coil, with a length-to-diameter ratio of 1-1.8 and made of 316L material; the high-level tank 3 is vertical and made of 304L material.

[0016] The stirrer in reactor 6 is a frame stirrer with a stirring speed of 250-300 r / min. This structure ensures that phosgene and amine groups are in full contact and can quickly remove hydrogen chloride.

[0017] The first flow meter B1 and the second flow meter B2 are mass flow meters.

[0018] Due to the strong permeability of amines, the second regulating valve F2 is a bellows type regulating valve, and the second switching valve D2 is a plug type.

[0019] Working process: Electric pump 2 transports the catalyst from catalyst storage tank 1 to high-level tank 3. When amine needs to be added, the second switch valve D2 on the amine inlet pipe 7 is opened according to the required amount, and the opening of the second regulating valve F2 is adjusted. When the second flow meter B2 displays the set value, due to the interlocking control of the first regulating valve F1, the first switch valve D1, and the second flow meter B2, the first regulating valve F1 and the first switch valve D1 are automatically opened. At the same time, due to the interlocking control of the first flow meter B1 and the first regulating valve F1, the opening of the first regulating valve F1 is automatically adjusted according to the set catalyst flow rate, so that the catalyst is continuously and automatically added to the reactor 6, thereby protecting the amine catalytic reaction rate. When the amine addition is complete and the second flow meter B2 displays 0, the first regulating valve F1, the first switch valve D1, the second regulating valve F2, and the second switch valve D2 are closed. The entire automatic feeding is realized through the DCS control system.

[0020] During the reaction, the heat or cold energy of the reactor 6 is transferred through the jacket (coil) to the required heat or cold medium, removing the heat required for the reaction or transferring the heat required for the reaction.

[0021] The above description is merely a conventional embodiment of this utility model and does not constitute any limitation on the structure of this utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model shall still fall within the scope of the technical solution of this utility model.

Claims

1. An apparatus for adding a catalyst in an isocyanate reaction, comprising a reaction vessel (6), characterized in that, The discharge pipe on the catalyst storage tank (1) is connected to the high-level tank (3) via an electric pump (2). The bottom of the high-level tank (3) is connected to the liquid outlet pipe (4). The liquid outlet pipe (4) is equipped with a first flow meter (B1), a first regulating valve (F1), and a first switching valve (D1) in sequence. The first switching valve (D1) is connected to the reactor (6). Another feed port on the reactor (6) is connected to the amine inlet pipe (7) via the second switching valve (D2). The amine inlet pipe (7) is connected to the second flow meter (B2) and the second regulating valve (F2). The reactor (6) is also equipped with an insertion pipe (9) for introducing phosgene or phosgene solution. The second flow meter (B2) is interlocked with the first switching valve (D1) and the first regulating valve (F1), and the first flow meter (B1) is interlocked with the first regulating valve (F1).

2. The apparatus for adding a catalyst in an isocyanate reaction as described in claim 1, characterized in that, The top of the high-level tank (3) is provided with a first exhaust pipe (5), and the top of the reactor (6) is provided with a second exhaust pipe (8). The second exhaust pipe (8) is provided with a safety valve (F) for protecting the equipment.

3. The apparatus for adding a catalyst in an isocyanate reaction as described in claim 1 or 2, characterized in that, The high-level tank (3) is located 3-4m above the reactor (6) to enable the catalyst to flow by gravity; a level gauge is installed on the high-level tank (3) to measure the storage and outflow.

4. The apparatus for adding a catalyst in an isocyanate reaction as described in claim 1, characterized in that, The reactor (6) is equipped with a stirrer, a thermometer, a pressure gauge and a level gauge for observing and controlling process parameters.

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