A crude separation device for dipropylene glycol production

Abstract

The utility model relates to a kind of for the crude separation device of one dipropylene glycol production, including flash evaporator (V1), feed pump (P1), crude column (T1), heat pump unit (P2), membrane reboiler (E1), cryogenic unit (E2), reflux tank (V2), reflux pump (P3), column kettle pump (P4).The utility model can reduce the consumption of steam and circulating water in production process, reduce production energy consumption and production cost.

Description

[0001] This utility model relates to the field of dipropylene glycol production, and more particularly to a crude separation device for dipropylene glycol production. Background Technology

[0002] Dipropylene glycol is an important organic synthesis intermediate, widely used in the production of plasticizers, polyester resins, cosmetics and fragrances, polyurethane polyols and alkyd resins.

[0003] In a large-scale dipropylene glycol production unit, propylene oxide and 1,2-propanediol are used as raw materials. Under certain temperature and pressure conditions, a catalytic reaction yields a mixture of dipropylene glycol and tripropylene glycol, along with unreacted propylene oxide and 1,2-propanediol. The reacted material is then fed to a coarse separator for purification. Unreacted propylene oxide and 1,2-propanediol are collected from the top of the separator and returned to the reaction unit for further reaction. The mixture of dipropylene glycol and tripropylene glycol is collected from the bottom of the separator and enters the subsequent dipropylene glycol purification unit. The reboiler in the coarse separator is heated with steam, and the condenser at the top of the separator uses circulating water for condensation. The production process involves a high reflux ratio, high heat load, and consumes large amounts of steam and circulating water, resulting in high energy consumption and costs. Summary of the Invention

[0004] To address the shortcomings mentioned above, this invention proposes a crude separation device for the production of dipropylene glycol, which consumes less steam and circulating water, reduces production energy consumption and costs, and is simple and stable to operate, facilitating continuous and large-scale operation.

[0005] This utility model discloses a crude separation device for the production of dipropylene glycol diasyl chloride. The technical solution is as follows: A crude separation device for the production of dipropylene glycol diasyl chloride includes a flash evaporator V1, a feed pump P1, a crude separation tower T1, a heat pump unit P2, a membrane reboiler E1, a cryotherm E2, a reflux tank V2, a reflux pump P3, and a bottom pump P4. The side inlet of the flash evaporator V1 is connected to the feed pipeline, the top gas outlet of the flash evaporator V1 is connected to the reaction unit, the liquid outlet of the flash evaporator V1 is connected to the inlet of the feed pump P1, the outlet of the feed pump P1 is connected to the inlet of the crude separation tower T1, the outlet of the feed pump P1 is connected to the top inlet of the flash evaporator V1, and the top outlet of the crude separation tower T1 is connected to the inlet of the heat pump unit P2. The outlet of P2 is connected to the hot-side inlet of membrane reboiler E1. The cold-side outlet of membrane reboiler E1 is connected to the hot-side inlet of cryogenic reactor E2. The cold-side outlet of cryogenic reactor E2 is connected to the inlet of reflux tank V2. The gas phase outlet of reflux tank V2 is connected to the tail gas treatment system. The liquid phase outlet of reflux tank V2 is connected to the inlet of reflux pump P3. The outlet of reflux pump P3 is connected to the reflux inlet of coarse separator T1. The outlet of reflux pump P3 is connected to the top product pipeline. The bottom outlet of coarse separator T1 is connected to the inlet of bottom pump P4. The outlet of bottom pump P4 is connected to the cold-side inlet of membrane reboiler E1. The cold-side outlet after heat exchange of membrane reboiler E1 is connected to the bottom of coarse separator T1. The outlet of bottom pump P4 is connected to the feed pipeline of dipropylene glycol refining unit.

[0006] Preferably, a regulating valve b is installed on the gas outlet pipeline at the top of the flash evaporator V1 to control the pressure of the flash evaporator V1.

[0007] Preferably, the flash evaporator V1 is provided with a packing layer a.

[0008] Preferably, the heat pump unit P2 adopts a variable frequency motor c, and a pressure gauge d is installed on the outlet pipeline of the heat pump unit P2. The pressure gauge d and the variable frequency motor c are interlocked for instrument control.

[0009] The advantages and beneficial effects of this invention are as follows: After undergoing a high-temperature and high-pressure reaction in the reactor, the reactants, containing dipropylene glycol, tripropylene glycol, propylene oxide, and 1,2-propanediol, enter a flash evaporator for low-pressure flash evaporation. This flash evaporation converts most of the propylene oxide and some of the 1,2-propanediol into a gaseous phase, which is then separated from the top of the flash evaporator. Simultaneously, a portion of the liquid is returned by the feed pump and subjected to rough distillation through the packing layer within the flash evaporator, preventing excessive entrainment of dipropylene glycol and tripropylene glycol in the flash vapor. The high-temperature and high-pressure reactants are partially separated from propylene oxide and 1,2-propanediol through flash evaporation, reducing steam consumption in subsequent separations. The coarse separation tower uses a heat pump unit to recover heat from the top of the tower to heat the bottom, reducing steam consumption in the reboiler and circulating water consumption in the top condenser, thus lowering energy consumption in the production process. The outlet pressure of the heat pump unit is adjusted by a variable frequency motor to ensure that the material temperature at the heat pump outlet is as low as possible while still meeting heat exchange requirements, guaranteeing product quality and yield. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of this utility model.

[0011] Figure reference numerals: V1 flash evaporator, P1 feed pump, T1 coarse separator, P2 heat pump unit, E1 membrane reboiler, E2 cryocooler, V2 reflux tank, P3 reflux pump, P4 bottom pump, a packing layer, b regulating valve, c variable frequency motor, d pressure gauge. Detailed Implementation

[0012] 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.

[0013] Example 1, refer to Appendix Figure 1This utility model discloses a crude separation device for the production of dipropylene glycol, comprising a flash evaporator V1, a feed pump P1, a crude separation tower T1, a heat pump unit P2, a membrane reboiler E1, a cryotherm E2, a reflux tank V2, a reflux pump P3, and a bottom pump P4. The side inlet of the flash evaporator V1 is connected to the feed pipeline, the top gas outlet of the flash evaporator V1 is connected to the reaction unit, the liquid outlet of the flash evaporator V1 is connected to the inlet of the feed pump P1, the outlet of the feed pump P1 is connected to the inlet of the crude separation tower T1, the outlet of the feed pump P1 is connected to the top inlet of the flash evaporator V1, the top outlet of the crude separation tower T1 is connected to the inlet of the heat pump unit P2, and the outlet of the heat pump unit P2 is connected to the membrane reboiler E1. The membrane reboiler E1 hot-side cold outlet is connected to the cryogenic E2 hot-side inlet. The cryogenic E2 hot-side cold outlet is connected to the reflux tank V2 inlet. The reflux tank V2 gas phase outlet is connected to the tail gas treatment system. The reflux tank V2 liquid phase outlet is connected to the reflux pump P3 inlet. The reflux pump P3 outlet is connected to the coarse separator T1 reflux inlet. The reflux pump P3 outlet is connected to the top product pipeline. The coarse separator T1 bottom outlet is connected to the bottom pump P4 inlet. The bottom pump P4 outlet is connected to the membrane reboiler E1 cold-side inlet. The membrane reboiler E1 cold-side heat exchange outlet is connected to the coarse separator T1 bottom. The bottom pump P4 outlet is connected to the dipropylene glycol refining unit feed pipeline.

[0014] The flash evaporator V1 is equipped with a regulating valve b at the top gas outlet pipeline, which controls the pressure of the flash evaporator V1.

[0015] The flash evaporator V1 described above is equipped with a packing layer a.

[0016] The heat pump unit P2 mentioned above uses a variable frequency motor c. A pressure gauge d is installed on the outlet pipeline of the heat pump unit P2. The pressure gauge d and the variable frequency motor c are interlocked for instrument control.

[0017] In use, the high-temperature, high-pressure mixture of dipropylene glycol, tripropylene glycol, propylene oxide, and 1,2-propanediol obtained from the synthesis reaction enters flash evaporator V1 for flash vaporization. The resulting propylene oxide and 1,2-propanediol mixture is returned to the reaction unit for reuse. The flash evaporator pressure is adjusted via the top gas phase regulating valve b to control the flash ratio. A portion of the liquid returned from the outlet of feed pump P1 enters the flash evaporator, where, in conjunction with the packing layer a, the flashed gas undergoes rough distillation to prevent excessive entrainment of dipropylene glycol and tripropylene glycol in the flash vapor. The liquid phase in the flash evaporator is pumped to the coarse fractionation column T1 for distillation, and the remaining propylene oxide and 1,2-propanediol in the reactants are collected from the top of the coarse fractionation column and recycled to the reaction unit. The coarse fractionation column uses a heat pump unit P2 to recover heat from the top of the column for heating the reboiler. The gas from the top of the coarse separator is pressurized and heated by a heat pump unit before entering the membrane reboiler E1 for heat exchange. The heat pump unit adjusts the outlet pressure d via a variable frequency motor c to ensure that the temperature and pressure of the compressed material meet the heat exchange requirements of the membrane reboiler. The gas from the heat pump unit outlet is condensed by the membrane reboiler and the cryocooler E2 before entering the reflux tank V2. The material in the reflux tank is partially transported to the coarse separator as reflux by the reflux pump P3, and partially collected and recycled to the reaction unit. The non-condensable gas from the top of the column is transported to the tail gas treatment system. The material in the bottom of the coarse separator is partially transported to the membrane reboiler E1 for heat exchange by the bottom pump P4, then vaporized and returned to the coarse separator, and partially collected and sent to the subsequent dipropylene glycol refining unit.

[0018] In implementing the technical solution of this embodiment, during the testing of a 50,000-ton-per-year dipropylene glycol production unit, the original production unit was modified according to the content of this utility model. The results of the unit's operational test after the modification are shown in the table below. This indicates that there was no significant difference in the composition and flow rate of the crude fractionation tower's reboiler before and after the modification; the system's steam and circulating water consumption decreased; the standard oil consumption per ton of product decreased by 83.8%; and production energy consumption and production costs were significantly reduced, achieving the expected results.

[0019] The above embodiments are merely one implementation of the crude separation device for the production of dipropylene glycol provided by this utility model. Any other modifications to the solution 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. A crude separation device for the production of dipropylene glycol, characterized in that: The system includes a flash evaporator (V1), a feed pump (P1), a coarse separator (T1), a heat pump unit (P2), a membrane reboiler (E1), a cryotherm (E2), a reflux tank (V2), a reflux pump (P3), and a bottom pump (P4). The flash evaporator (V1) has its side inlet connected to the feed line, its top gas outlet connected to the reaction unit, its liquid outlet connected to the inlet of the feed pump (P1), its outlet connected to the inlet of the coarse separator (T1), its outlet connected to the top inlet of the flash evaporator (V1), its top outlet connected to the inlet of the heat pump unit (P2), and its outlet connected to the hot-side inlet of the membrane reboiler (E1). The outlet of the hot side of the cryogenic unit (E1) after cooling is connected to the inlet of the hot side of the cryogenic unit (E2). The outlet of the hot side of the cryogenic unit (E2) after cooling is connected to the inlet of the reflux tank (V2). The gas phase outlet of the reflux tank (V2) is connected to the tail gas treatment system. The liquid phase outlet of the reflux tank (V2) is connected to the inlet of the reflux pump (P3). The outlet of the reflux pump (P3) is connected to the reflux inlet of the coarse separator (T1). The outlet of the reflux pump (P3) is connected to the top product pipeline. The bottom outlet of the coarse separator (T1) is connected to the inlet of the bottom pump (P4). The outlet of the bottom pump (P4) is connected to the cold side inlet of the membrane reboiler (E1). The outlet of the membrane reboiler (E1) after heat exchange on the cold side is connected to the bottom of the coarse separator (T1). The outlet of the bottom pump (P4) is connected to the feed pipeline of the dipropylene glycol refining unit.

2. The crude separation device for the production of dipropylene glycol according to claim 1, characterized in that: A regulating valve (b) is installed on the gas outlet pipeline at the top of the flash evaporator (V1) to control the pressure of the flash evaporator (V1).

3. A crude separation device for the production of dipropylene glycol according to claim 1, characterized in that: The flash evaporator (V1) is provided with a packing layer (a).

4. A crude separation device for the production of dipropylene glycol according to claim 1, characterized in that: The heat pump unit (P2) uses a variable frequency motor (c), and a pressure gauge (d) is installed on the outlet pipeline of the heat pump unit (P2). The pressure gauge (d) and the variable frequency motor (c) are interlocked for instrument control.

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