Device for continuously synthesizing dipropylene glycol

Abstract

The utility model relates to a device for continuously synthesizing dipropylene glycol. The device comprises a reactor (R1), a circulating heat exchanger (E1), a circulating pump (P1), a recovery condenser (E2), a feed pump (P2), a falling film separator (E3), a gas-liquid separation tank (V1), a recovery liquid pump (P3), a vacuum condenser (E4) and a vacuum pump (P4). The device disclosed by the utility model can be used for continuously synthesizing dipropylene glycol, and is stable in production process, large in production scale and high in product quality.

Description

Technical Field

[0001] This utility model relates to the field of dipropylene glycol production, and more particularly to an apparatus for the synthesis of dipropylene glycol. Background Technology

[0002] Dipropylene glycol is a multifunctional compound that is widely used in various fields such as polyester resin synthesis, personal care and cosmetics, pharmaceutical and pharmaceutical industries, and food and fragrance industries due to its low toxicity, good solubility and mild chemical properties.

[0003] In traditional dipropylene glycol synthesis units, propylene oxide and 1,2-propanediol are used as raw materials. The reaction, under the action of a catalyst, yields a mixture of 1,2-propanediol, dipropylene glycol, tripropylene glycol, and the catalyst. Part of the 1,2-propanediol, dipropylene glycol, and tripropylene glycol are vaporized by heating. The vaporized material is then condensed in a condenser and transported to the dipropylene glycol refining unit for purification. The reaction is primarily conducted in a reactor, and the entire process is intermittent, resulting in unstable production, large temperature fluctuations, small production scale, and significant quality variations between different batches of product. Summary of the Invention

[0004] To address the shortcomings mentioned above, this invention proposes an apparatus for the continuous synthesis of dipropylene glycol, which enables continuous production, has a high conversion rate, a stable and easily controllable production process, a large production scale, and stable product quality, fully meeting market demands.

[0005] This utility model discloses an apparatus for the continuous synthesis of dipropylene glycol. The technical solution is as follows: An apparatus for the continuous synthesis of dipropylene glycol includes a reactor (R1), a circulating heat exchanger (E1), a circulating pump (P1), a recovery condenser (E2), a feed pump (P2), a falling film separator (E3), a gas-liquid separator (V1), a recovery liquid pump (P3), a vacuum condenser (E4), and a vacuum pump (P4). The top gas phase outlet of the reactor (R1) is connected to the hot-side inlet of the recovery condenser (E2), the hot-side cooled outlet of the recovery condenser (E2) is connected to a propylene oxide recovery pipeline, the lower side outlet of the reactor (R1) is connected to the hot-side inlet of the circulating heat exchanger (E1), the hot-side cooled outlet of the circulating heat exchanger (E1) is connected to the inlet of the circulating pump (P1), the outlet of the circulating pump (P1) is connected to the upper inlet of the reactor (R1), and a propylene oxide feed pipe is provided. The feed line is connected to the lower side inlet of the reactor (R1). The feed line for 1,2-propanediol is connected to the outlet of the circulating pump (P1). The bottom outlet of the reactor (R1) is connected to the inlet of the feed pump (P2). The outlet of the feed pump (P2) is connected to the cold side inlet of the falling film separator (E3). The outlet of the falling film separator (E3) after heat exchange on the bottom cold side is connected to the side inlet of the gas-liquid separator (V1). The top gas phase outlet of the gas-liquid separator (V1) is connected to the hot side inlet of the vacuum condenser (E4). The cold gas phase outlet of the vacuum condenser (E4) on the hot side is connected to the inlet of the vacuum pump (P4). The outlet of the vacuum pump (P4) is connected to the tail gas recovery line. The cold liquid phase outlet of the vacuum condenser (E4) on the hot side is connected to the feed line of the dipropylene glycol refining unit. The bottom outlet of the gas-liquid separator (V1) is connected to the inlet of the recovery liquid pump (P3). The outlet of the recovery liquid pump (P3) is connected to the outlet of the circulating pump (P1).

[0006] Preferably, a pressure gauge (i) is installed at the top of the reactor (R1), and a regulating valve (h) is installed on the gas phase outlet pipeline at the top of the reactor (R1). The pressure gauge (i) and the regulating valve (h) are interlocked for instrument control.

[0007] Preferably, the lower side of the reactor (R1) has three propylene oxide inlets (a), (c), and (e), and the lower side of the reactor (R1) has three circulating liquid outlets (b), (d), and (f), with the propylene oxide inlets and circulating liquid outlets corresponding one-to-one.

[0008] Preferably, the propylene oxide feed inlet on the lower side of the reactor (R1) is equipped with a distribution plate (g) after entering the reactor.

[0009] Preferably, the temperature of the cold-side medium entering the circulating heat exchanger (E1) is 70~150°C.

[0010] The advantages and beneficial effects of this invention are as follows: The reactor adopts continuous feeding, and a circulating heat exchanger continuously removes the heat released by the reaction, resulting in a stable and easily controllable reaction temperature and a high conversion rate. The cold-side medium of the circulating heat exchanger uses a medium at 70~150℃, which can be used to heat the system during initial operation and to remove the heat of reaction during normal production. Different propylene oxide inlets and corresponding circulating liquid outlets are provided, allowing for adjustment of the reaction time according to the production scale to ensure the selectivity and yield of dipropylene glycol. The mixture after the reaction is separated using a negative pressure falling film separation method, resulting in a large separation ratio, reduced polymer formation, and the catalyst-containing circulating liquid can be recycled. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model.

[0012] Figure reference numerals: R1 reactor, E1 circulating heat exchanger, P1 circulating pump, E2 recovery condenser, P2 feed pump, E3 falling film separator, V1 gas-liquid separator, P3 recovery liquid pump, E4 vacuum condenser, P4 vacuum pump, a / c / e propylene oxide inlet, b / d / f circulating liquid outlet, g distribution plate, h regulating valve, i pressure gauge. Detailed Implementation

[0013] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0014] Example 1, refer to Appendix Figure 1This utility model discloses an apparatus for the continuous synthesis of dipropylene glycol, comprising a reactor (R1), a circulating heat exchanger (E1), a circulating pump (P1), a recovery condenser (E2), a feed pump (P2), a falling film separator (E3), a gas-liquid separator (V1), a recovery liquid pump (P3), a vacuum condenser (E4), and a vacuum pump (P4). The top gas phase outlet of the reactor (R1) is connected to the hot-side inlet of the recovery condenser (E2), the cold outlet of the hot-side of the recovery condenser (E2) is connected to a propylene oxide recovery pipeline, the lower side outlet of the reactor (R1) is connected to the hot-side inlet of the circulating heat exchanger (E1), the cold outlet of the hot-side of the circulating heat exchanger (E1) is connected to the inlet of the circulating pump (P1), the outlet of the circulating pump (P1) is connected to the upper inlet of the reactor (R1), and the raw material propylene oxide feed pipeline is connected to the lower side of the reactor (R1). The feed line for 1,2-propanediol is connected to the outlet of the circulating pump (P1). The bottom outlet of the reactor (R1) is connected to the inlet of the feed pump (P2). The outlet of the feed pump (P2) is connected to the cold side inlet of the falling film separator (E3). The outlet of the falling film separator (E3) after heat exchange on the bottom cold side is connected to the side inlet of the gas-liquid separator (V1). The top gas phase outlet of the gas-liquid separator (V1) is connected to the hot side inlet of the vacuum condenser (E4). The gas phase outlet of the vacuum condenser (E4) after cooling on the hot side is connected to the inlet of the vacuum pump (P4). The outlet of the vacuum pump (P4) is connected to the tail gas recovery line. The liquid phase outlet of the vacuum condenser (E4) after cooling on the hot side is connected to the feed line of the dipropylene glycol refining unit. The bottom outlet of the gas-liquid separator (V1) is connected to the inlet of the recovery liquid pump (P3). The outlet of the recovery liquid pump (P3) is connected to the outlet of the circulating pump (P1).

[0015] The reactor (R1) is equipped with a pressure gauge (i) at the top and a regulating valve (h) is installed on the gas phase outlet pipeline at the top of the reactor (R1). The pressure gauge (i) and the regulating valve (h) are interlocked for instrument control.

[0016] The reactor (R1) has three propylene oxide inlets (a), (c), and (e) on its lower side, and three circulating liquid outlets (b), (d), and (f) on its lower side. The propylene oxide inlets and circulating liquid outlets correspond one-to-one.

[0017] The propylene oxide feed inlet on the lower side of the reactor (R1) is equipped with a distribution plate (g) after entering the reactor.

[0018] The cold-side medium of the aforementioned circulating heat exchanger (E1) enters the circulating heat exchanger at a temperature of 100°C.

[0019] In use, the raw material 1,2-propanediol and the catalyst recovery liquid are mixed with the material conveyed by the circulating pump (P1) and continuously fed into the reactor. The raw material propylene oxide continuously enters the reactor (R1) through port (c), and the circulating liquid enters the circulating heat exchanger (E1) through the circulating liquid outlet (d) of the reactor (R1). The heat of reaction is removed through the circulating heat exchanger, and the cold side medium of the circulating heat exchanger uses material from other devices at 100°C for heat exchange to recover heat. The opening of the regulating valve (h) is adjusted according to the pressure displayed on the pressure gauge (i) at the top of the reactor to control the reactor pressure and prevent overpressure. The discharged propylene oxide gas is condensed and recycled after passing through the recovery condenser (E2). Propylene oxide and 1,2-propanediol react in the reactor to produce dipropylene glycol and a small amount of tripropylene glycol. The products and catalyst enter the falling film separator (E3) for negative pressure separation. The separation temperature is low, resulting in less polymer formation. The material evaporated by the falling film separator is condensed by the vacuum condenser (E4), and the liquid phase enters the dipropylene glycol unit for purification. The non-condensable gas is transported to the tail gas treatment unit by the vacuum pump (P4), and the catalyst recovery liquid is transported back to the reactor for recycling by the recovery liquid pump (P3).

[0020] In implementing the technical solution of this embodiment, during the testing of a batch production unit with an annual output of 1500 tons of dipropylene glycol, the original production unit was modified according to the content of this utility model. The results of the unit's operation test after the modification are shown in the table below, indicating that the quality of the produced dipropylene glycol meets the specified requirements, the propylene oxide conversion rate is high, the production scale is large, the equipment investment is low, and the expected results are achieved.

[0021] project Dipropylene glycol production propylene oxide conversion rate Mass of dipropylene glycol Number of operators Equipment investment Before renovation 135 tons / 30 days 0.972 99.82% 3 people 17 million yuan After renovation 421 tons / 30 days 0.981 99.87% 1 person 9.3 million yuan

[0022] The above embodiments are merely one implementation of the apparatus for the continuous synthesis of dipropylene glycol provided by this utility model. Any other modifications to the scheme provided by this utility model, including adding or removing components, or applying this utility model to other technical fields similar to this utility model, shall all fall within the protection scope of this utility model.

Claims

1. An apparatus for the continuous synthesis of dipropylene glycol, characterized by: The reactor (R1), the circulating heat exchanger (E1), the circulating pump (P1), the recovery condenser (E2), the feed pump (P2), the falling film separator (E3), the gas-liquid separation tank (V1), the recovery liquid pump (P3), the vacuum condenser (E4), and the vacuum pump (P4) are connected, the top gas phase outlet of the reactor (R1) is connected with the hot side inlet of the recovery condenser (E2), the cold outlet of the hot side of the recovery condenser (E2) is connected with the propylene oxide recovery pipeline, the lower side outlet of the reactor (R1) is connected with the hot side inlet of the circulating heat exchanger (E1), the cold outlet of the hot side of the circulating heat exchanger (E1) is connected with the inlet of the circulating pump (P1), the outlet of the circulating pump (P1) is connected with the upper inlet of the reactor (R1), the raw material propylene oxide feed pipeline is connected with the lower side inlet of the reactor (R1), the raw material 1,2-propylene glycol feed pipeline is connected with the outlet of the circulating pump (P1), the bottom outlet of the reactor (R1) is connected with the inlet of the feed pump (P2), the outlet of the feed pump (P2) is connected with the cold side inlet of the falling film separator (E3), the bottom cold side heat exchanged outlet of the falling film separator (E3) is connected with the side inlet of the gas-liquid separation tank (V1), the top gas phase outlet of the gas-liquid separation tank (V1) is connected with the hot side inlet of the vacuum condenser (E4), the cold gas phase outlet of the hot side of the vacuum condenser (E4) is connected with the inlet of the vacuum pump (P4), the outlet of the vacuum pump (P4) is connected with the tail gas recovery pipeline, the cold liquid phase outlet of the hot side of the vacuum condenser (E4) is connected with the monopropylene glycol refining unit feed pipeline, the bottom outlet of the gas-liquid separation tank (V1) is connected with the inlet of the recovery liquid pump (P3), and the outlet of the recovery liquid pump (P3) is connected with the outlet of the circulating pump (P1).

2. A device for the continuous synthesis of dipropylene glycol according to claim 1, characterized in that: The pressure gauge (i) is arranged at the top of the reactor (R1), the adjusting valve (h) is arranged on the gas phase outlet pipeline of the reactor (R1), and the pressure gauge (i) and the adjusting valve (h) are arranged in instrument control interlocking.

3. A device for the continuous synthesis of dipropylene glycol according to claim 1, characterized in that: The lower side of the reactor (R1) is provided with three epoxy propylene feeding ports (a), (c) and (e), and three circulating liquid outlets (b), (d) and (f) are arranged on the lower side of the reactor (R1), and the epoxy propylene feeding port and the circulating liquid outlet are one-to-one corresponding.

4. The apparatus for continuous synthesis of dipropylene glycol according to claim 1, characterized in that: The epoxy propylene feeding port of the lower side of the reactor (R1) is provided with a distribution plate (g) after entering the reactor.

5. The apparatus for the continuous synthesis of dipropylene glycol according to claim 1, characterized in that: The cold side medium of the circulating heat exchanger (E1) has a temperature of 70-150 ℃ after entering the circulating heat exchanger.

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