Separation system for high-water-content low-carbon alcohol

Abstract

The utility model belongs to the field of chemical industry, and relates to a high-water-content low-carbon alcohol separation system, which comprises a first coarse separation tower, a second coarse separation tower, a stripping tower, a regeneration tower, a methanol tower, an ethanol tower, an isopropanol tower, an n-propanol tower and an n-butanol tower, each tower is provided with a condenser and a reboiler, and a manner of coarse dehydration and extractive distillation dehydration is adopted for mixed alcohol raw materials. Coarse dehydration, namely dehydration by a coarse separation tower and a stripping tower, can remove about two thirds of water with lower energy consumption; compared with an azeotropic distillation dehydration process, the extractive distillation dehydration process is lower in energy consumption and higher in efficiency, a heat exchange network of the separation process is optimized, and energy consumption is greatly reduced.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry and relates to a separation system for high-water-content low-carbon alcohol. Background Art

[0002] Low-carbon mixed alcohols primarily come from byproducts produced in coal-to-liquids plants, the large amounts of fusel alcohols found in methanol plants, and the presence of fusel alcohols in the brewing industry. These low-carbon mixed alcohols contain relatively high water contents, exceeding 20%. They include water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, and other polyols. These low-carbon alcohols are crucial industrial solvents and raw materials in the chemical and pharmaceutical industries. Separating these low-carbon mixed alcohols to obtain high-purity monoalcohols would benefit the economics of the coal-to-liquids and methanol industries, address environmental concerns, and improve the quality of brewing products. Low-carbon mixed alcohols contain a high water content, and water and various components in the low-carbon mixed alcohols form azeotropes. Failure to remove the water makes subsequent production of high-purity monoalcohols difficult.

[0003] Chinese patent CN105669377A discloses a process for separating mixed alcohols. The method adopts ordinary distillation + azeotropic dehydration. The raw materials are separated by a light removal tower, and the light components and methanol are removed from the top of the tower and sent to a methanol pressure tower. After separation in the methanol pressure tower, the light components are extracted from the top of the tower, and a methanol product is obtained at the bottom of the tower; the bottom material of the light removal tower is sent to an azeotropic tower, azeotropically dehydrated with an entrainer cyclohexane, and an aqueous solution containing the entrainer and alcohol enters a pressurized stripping tower, separated by the pressurized stripping tower, and wastewater is discharged from the bottom of the tower. The top material returns to the azeotropic tower for further distillation; the water-free mixed alcohol at the bottom of the azeotropic tower passes through an ethanol tower, a propanol tower, and a butanol tower in sequence to obtain ethanol, propanol, butanol, and heavy alcohol. In terms of energy saving, the top gas phase of the butanol tower is used as the heat source for the reboiler of the de-light tower, the top gas phase of the propanol tower is used as the heat source for the reboiler of the methanol pressure tower, the pressure stripping tower is used as the heat source for the reboiler of the azeotropic tower, and the top gas phase of the de-light tower and the waste water at the bottom of the pressure stripping tower are used to preheat the raw materials in sequence. This process has the following disadvantages: (1) All water in this process needs to be removed in an azeotropic manner through an entrainer. The entrainer circulation volume is very large. Although the coupled heat exchange method is used to save energy, the energy consumption is still very high, which is particularly obvious when the raw material has a high water content. (2) This process has relatively strict requirements on raw materials. The mixed alcohol after dehydration is obtained by single-tower distillation to obtain the corresponding products. If there are impurities between ethanol and propanol, or between propanol and butanol, the purity of the ethanol, propanol and butanol products will decrease accordingly.

[0004] Therefore, it is necessary to develop a new separation system for mixed alcohols. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings of the existing technology and provide a separation system for high-water-content low-carbon alcohols, which separates mixed alcohols by crude dehydration, extractive distillation dehydration combined with ordinary distillation methods, and saves energy by optimizing the heat exchange network and making full use of waste heat recovery technology.

[0006] The technical solution adopted by the utility model to solve the technical problem is:

[0007] The utility model provides a separation system for high-water-content low-carbon alcohol, comprising a coarse separation tower, a coarse separation tower heat exchange cooler, a coarse separation tower circulating water cooler, a coarse separation tower phase separation tank, a stripping tower, a stripping tower feed preheater, an extraction tower, a regeneration tower, a methanol tower, an ethanol tower, an isopropanol tower, a n-propanol tower and an n-butanol tower, each tower being equipped with a corresponding reboiler and a condenser, the coarse separation tower having a raw material inlet, a raw material preheater being arranged on the inlet pipeline, a side line 1 being provided at the upper part of the coarse separation tower, the side line 1 being connected to the inlet of the extraction tower through a pipeline, the bottom outlet of the extraction tower being connected to the inlet of the regeneration tower through a pipeline, and the gas phase extraction outlet at the top of the regeneration tower being connected to the inlet of the regeneration tower condenser through a pipeline. The outlet of the regeneration tower condenser is divided into two routes, one is connected to the reflux port of the regeneration tower, and the other is connected to the first inlet of the stripping tower; the bottom outlet of the regeneration tower passes through the ethanol tower heat exchange reboiler and the raw material preheater in sequence through the pipeline to enter the extractant inlet of the extraction tower, the top outlet of the extraction tower passes through the extraction tower condenser through the pipeline and is divided into two routes, one is connected to the reflux port of the extraction tower, and the other is connected to the inlet of the methanol tower. The methanol tower is equipped with a methanol tower steam reboiler, a methanol tower heat exchange reboiler 1, and a methanol tower heat exchange reboiler 2. The bottom outlet of the methanol tower is connected to the inlet of the ethanol tower through a pipeline, and the bottom outlet of the ethanol tower is connected to the inlet of the isopropanol tower through a pipeline. The bottom outlet of the tower is connected to the inlet of the n-propanol tower through a pipeline. The bottom of the n-propanol tower is the isobutanol product extraction pipeline. The top gas phase pipeline of the n-propanol tower is divided into two paths after passing through the second heat exchange reboiler of the methanol tower, one path is connected to the reflux port of the n-propanol tower, and the other path is used as the n-propanol product extraction pipeline; the lower part of the coarse fractionation tower is provided with a side line 2, which passes through the coarse fractionation tower heat exchange cooler and the coarse fractionation tower circulating water cooler through a pipeline and enters the coarse fractionation tower phase separation tank. The organic phase outlet of the coarse fractionation tower phase separation tank is connected to the inlet of the coarse fractionation tower through a pipeline through the coarse fractionation tower heat exchange cooler, and the water phase outlet of the coarse fractionation tower phase separation tank is connected to the first phase separation tank of the coarse fractionation tower through a pipeline through the stripping tower feed preheater. Two inlets; the bottom outlet of the stripping tower enters the stripping tower feed preheater through a pipeline and serves as a wastewater discharge pipeline; the top gas phase outlet of the stripping tower is connected to the inlet of the stripping tower condenser through a pipeline, and the outlet pipeline of the stripping tower condenser is divided into two paths, one is connected to the reflux port, and the other is connected to the inlet of the phase separation tank of the coarse separation tower after passing through the circulating water cooler of the coarse separation tower; the bottom outlet of the coarse separation tower is connected to the inlet of the n-butanol tower through a pipeline, and the top gas phase production pipeline of the n-butanol tower is divided into two paths after passing through the methanol tower heat exchange reboiler 1, one is connected to the reflux port of the n-butanol tower through a pipeline, and the other is used as the n-butanol product production pipeline, and the bottom production pipeline of the n-butanol tower is the heavy alcohol production pipeline.

[0008] Furthermore, it also includes a coarse separation tower, a coarse separation tower steam reboiler, a coarse separation tower condenser, and a coarse separation tower reflux phase separation tank. The coarse separation tower is equipped with a coarse separation tower heat exchange reboiler and a coarse separation tower steam reboiler. The coarse separation tower phase separation tank is installed at the bottom of the coarse separation tower. The bottom extraction pipeline of the coarse separation tower is divided into two routes, one of which is directly connected to the inlet of the coarse separation tower, and the other is connected to the inlet of the coarse separation tower after passing through the coarse separation tower phase separation tank and the coarse separation tower phase exchange cooler; the bottom extraction outlet of the coarse separation tower is connected to the inlet of the n-butanol tower through a pipeline, and the gas phase extraction pipeline at the top of the coarse separation tower passes through the coarse separation tower in sequence. The heat exchange reboiler of the first crude separation tower and the condenser of the second crude separation tower are connected to the inlet of the reflux phase-separation tank of the second crude separation tower. The organic phase outlet of the reflux phase-separation tank of the second crude separation tower is connected to the reflux port of the top of the second crude separation tower through a pipeline. The water phase outlets of the phase-separation tank of the first crude separation tower and the reflux phase-separation tank of the second crude separation tower are both connected to the first inlet of the stripping tower through a pipeline after passing through the stripping tower feed preheater. The top outlet of the stripping tower is connected to the inlet of the stripping tower condenser through a pipeline. The outlet pipeline of the stripping tower condenser is divided into two routes, one route is connected to the reflux port of the stripping tower, and the other route is connected to the inlet of the reflux phase-separation tank of the second crude separation tower after passing through the condenser of the second crude separation tower.

[0009] Furthermore, the top extraction pipeline of the crude fraction tower is connected to the condenser of the crude fraction tower, the gas phase outlet of the condenser of the crude fraction tower is used to discharge non-condensable gas, and the liquid phase outlet pipeline of the condenser of the crude fraction tower is divided into two routes, one route is connected to the reflux inlet of the crude fraction tower, and the other route is used as the methanol product extraction pipeline.

[0010] Furthermore, the outlet pipelines of the methanol tower condenser, ethanol tower condenser and isopropanol tower condenser respectively equipped on the top of the methanol tower, ethanol tower and isopropanol tower are divided into two routes, one route is connected to the reflux port of the methanol tower, ethanol tower and isopropanol tower respectively, and the other route is used as the methanol product production pipeline, ethanol product production pipeline and isopropanol product production pipeline respectively.

[0011] Furthermore, the process method of the separation system of the high-water-content low-carbon alcohol is as follows: the coarse fractionation tower only includes a coarse fractionation tower 1, the mixed alcohol raw material is preheated in a raw material preheater and then fed into the coarse fractionation tower 1, the overhead gas phase of the coarse fractionation tower 1 enters the coarse fractionation tower 1 condenser for condensation, the non-condensable gas is discharged, a portion of the condensed liquid is returned to the coarse fractionation tower 1 as reflux, and a portion is extracted as a methanol product;

[0012] The crude fractionation tower is a normal pressure tower with a top pressure of -10-50kpa, a top temperature of 40-90℃, and a bottom temperature of 110-150℃. The mixed solution of methanol, ethanol, propanol, a small amount of butanol and water extracted from the side line of the upper part of the crude fractionation tower is sent to the middle of the extraction tower, and the extractant is added from the upper middle part of the extraction tower; the extractant and water at the bottom of the extraction tower are sent to the regeneration tower, and the gas phase at the top of the regeneration tower enters the regeneration tower condenser for condensation. Part of the condensed liquid is returned to the regeneration tower as reflux, and part is extracted to the stripping tower for stripping as wastewater; the extractant at the bottom of the regeneration tower passes through the ethanol tower heat exchange reboiler and the crude fractionation tower raw material preheater in turn and returns to the extraction tower for recycling. The gas phase at the top of the extraction tower enters the extraction tower condenser for condensation. Part of the condensed liquid is returned to the extraction tower as reflux, and part is extracted to the methanol tower. The gas phase at the top of the methanol tower enters The methanol tower condenser is condensed, and a part of the condensed liquid is returned to the methanol tower as reflux, and a part is extracted as the methanol product. The ethanol, n-propanol and a small amount of isopropanol and butanol mixed solution at the bottom of the methanol tower are sent to the ethanol tower. The gas phase at the top of the ethanol tower enters the ethanol tower condenser for condensation, and a part of the condensed liquid is returned to the ethanol tower as reflux, and a part is extracted as the ethanol product. The bottom material of the ethanol tower is sent to the isopropanol tower. The gas phase at the top of the isopropanol tower enters the isopropanol tower condenser for condensation, and a part of the condensed liquid is returned to the isopropanol tower as reflux, and a part is extracted as the isopropanol product. The bottom material of the isopropanol tower is sent to the n-propanol tower. The gas phase at the top of the n-propanol tower enters the methanol tower heat exchange reboiler for secondary condensation, and a part of the condensed liquid is returned to the n-propanol tower as reflux, and a part is extracted as the n-propanol product. The isobutanol product is extracted from the bottom of the n-propanol tower;

[0013] Heavy alcohols such as butanol and pentanol are produced from the bottom of the crude fractionation tower and sent to the n-butanol tower. The gas phase at the top of the n-butanol tower enters the heat exchange reboiler 1 of the methanol tower for condensation. Part of the condensed liquid is returned to the n-butanol tower as reflux, and part is produced as the n-butanol product. The heavy alcohol product is produced from the bottom of the n-butanol tower; the butanol and water produced from the side line 2 at the bottom of the crude fractionation tower enter the phase separation tank of the crude fractionation tower for phase separation after cooling, and the organic phase returns to the crude fractionation tower after heat exchange in the cooler of the crude fractionation tower; the water phase is preheated in the stripping tower feed preheater and sent to the stripping tower. The gas phase at the top of the stripping tower enters the stripping tower condenser for condensation, and part of the condensed liquid is returned to the stripping tower as reflux, and part is produced to the phase separation tank of the crude fractionation tower for phase separation. The waste water at the bottom of the stripping tower is produced and discharged after cooling in the stripping tower feed preheater.

[0014] Furthermore, the process method of the separation system of the high-water-content low-carbon alcohol is as follows: the coarse separation tower includes a coarse separation tower 1 and a coarse separation tower 2; the mixed alcohol raw material is preheated in a raw material preheater and then fed into the coarse separation tower 1; the overhead gas phase of the coarse separation tower 1 enters the coarse separation tower 1 condenser for condensation; the non-condensable gas is discharged; part of the condensed liquid is returned to the coarse separation tower 1 as reflux, and part is extracted as a methanol product;

[0015] The crude fractionation tower is a normal pressure tower with a top pressure of -10-50kpa, a top temperature of 40-90°C, and a bottom temperature of 70-120°C. The mixed solution of methanol, ethanol, propanol, a small amount of butanol and water extracted from the side line of the upper part of the crude fractionation tower is sent to the middle of the extraction tower, and the extractant is added from the upper middle part of the extraction tower; the extractant and water at the bottom of the extraction tower are sent to the regeneration tower, and the gas phase at the top of the regeneration tower enters the regeneration tower condenser for condensation. Part of the condensed liquid is returned to the regeneration tower as reflux, and part is extracted to the stripping tower for stripping as wastewater; the extractant at the bottom of the regeneration tower passes through the ethanol tower heat exchange reboiler and the crude fractionation tower raw material preheater in turn and then returns to the extraction tower for recycling. The gas phase at the top of the extraction tower enters the extraction tower condenser for condensation. Part of the condensed liquid is returned to the extraction tower as reflux, and part is extracted to the methanol tower. The gas phase at the top of the methanol tower enters the methanol tower condenser The alcohol tower condenser is condensed, and a part of the condensed liquid is returned to the methanol tower as reflux, and a part is extracted as the methanol product. The ethanol, n-propanol and a small amount of isopropanol and butanol mixed solution at the bottom of the methanol tower are sent to the ethanol tower. The top gas phase of the ethanol tower enters the ethanol tower condenser for condensation, and a part of the condensed liquid is returned to the ethanol tower as reflux, and a part is extracted as the ethanol product. The bottom material of the ethanol tower is sent to the isopropanol tower. The top gas phase of the isopropanol tower enters the isopropanol tower condenser for condensation, and a part of the condensed liquid is returned to the isopropanol tower as reflux, and a part is extracted as the isopropanol product. The bottom material of the isopropanol tower is sent to the n-propanol tower. The top gas phase of the n-propanol tower enters the methanol tower heat exchange reboiler for secondary condensation, and a part of the condensed liquid is returned to the n-propanol tower as reflux, and a part is extracted as the n-propanol product. The isobutanol product is extracted from the bottom of the n-propanol tower;

[0016] Heavy alcohols such as butanol and amyl alcohol are extracted from the bottom of the crude separation tower 1 and are cooled and then enter the phase separation tank of the crude separation tower 1 for phase separation. The organic phase is sent to the crude separation tower 2 after heat exchange in the phase separation cooler of the crude separation tower 1. The crude separation tower 2 (37) is a pressurized tower with a top pressure of 100-300kPa, a top temperature of 100-150°C, and a bottom temperature of 120-170°C. The gas phase at the top of the crude separation tower 2 is sent to the heat exchange reboiler of the crude separation tower 1 for condensation. The condensed liquid enters the reflux phase separation tank of the crude separation tower 2. The organic phase of the reflux phase separation tank of the crude separation tower 2 enters the crude separation tower 2. The water phases of the phase separation tank of the crude separation tower 1 and the reflux phase separation tank of the crude separation tower 2 are separated. The phases are preheated by the stripping tower feed preheater and then enter the stripping tower. The gas phase at the top of the stripping tower enters the stripping tower condenser for condensation. Part of the condensed liquid is returned to the stripping tower as reflux, and part is extracted to the reflux phase separation tank of the coarse separation tower for phase separation. The waste water at the bottom of the stripping tower is extracted and discharged after being cooled in the stripping tower feed preheater. The material from the bottom of the coarse separation tower is sent to the n-butanol tower. The gas phase at the top of the n-butanol tower enters the methanol tower heat exchange reboiler for condensation. Part of the condensed liquid is returned to the n-butanol tower as reflux, and part is extracted as the n-butanol product. The heavy alcohol product is extracted from the bottom of the n-butanol tower.

[0017] Furthermore, the stripping tower is a normal pressure tower, with a top pressure of -10-50 kPa, a top temperature of 60-95°C, and a bottom temperature of 80-120°C; the extraction tower is a vacuum tower, with a top pressure of -90 kPa to normal pressure, a top temperature of 40-90°C, and a bottom temperature of 100-160°C; the regeneration tower is a vacuum tower, with a top pressure of -95-20 kPa, a top temperature of 40-90°C, and a bottom temperature of 120-170°C; the methanol tower is a normal pressure tower, with a top pressure of -20-100 kPa, a top temperature of 40-90°C, and a bottom temperature of 60-110°C; The ethanol tower is a negative pressure tower with a top pressure of -80kPa to normal pressure, a top temperature of 40-80°C, and a bottom temperature of 60-110°C. The isopropanol tower is a normal pressure tower with a top pressure of -20-100kPa, a top temperature of 60-100°C, and a bottom temperature of 80-130°C. The n-propanol tower is a normal pressure tower with a top pressure of -20-100kPa, a top temperature of 60-100°C, and a bottom temperature of 80-130°C. The n-butanol tower is a normal pressure tower with a top pressure of -20-100kPa, a top temperature of 100-140°C, and a bottom temperature of 120-170°C.

[0018] Furthermore, the heat exchange cooler of the coarse separation tower uses the organic phase of the coarse separation tower phase separation tank as the refrigerant; the circulating water cooler of the coarse separation tower uses circulating water as the refrigerant, and the cooling temperature is 30-80°C; the stripping tower feed preheater uses the wastewater extracted from the bottom of the stripping tower as the heat source, and the stripping tower steam reboiler, the extraction tower steam reboiler, and the regeneration tower steam reboiler all use water vapor as the heat source.

[0019] Furthermore, the methanol tower is equipped with three reboilers, one is a methanol tower steam reboiler, which uses water vapor as a heat source; one is a methanol tower heat exchange reboiler 1, which uses the top gas phase of the n-butanol tower as a heat source; and one is a methanol tower heat exchange reboiler 2, which uses the top gas phase of the n-propanol tower as a heat source.

[0020] Furthermore, the ethanol tower is equipped with three reboilers, one is an ethanol tower steam reboiler, which uses water vapor as a heat source; one is an ethanol tower hot water reboiler, which uses steam condensed water as a heat source; and another is an ethanol tower heat exchange reboiler, which uses the extractant at the bottom of the extraction tower as a heat source.

[0021] Furthermore, the extractant is one or more of ethylene glycol, 1,3-propylene glycol, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), N-formylmorpholine (NFM), and dimethyl sulfoxide (DMSO).

[0022] The advantages and positive effects of the utility model are:

[0023] 1. The separation system of the high-water-content low-carbon alcohol of the utility model reduces the energy consumption of the separation of mixed alcohols and adopts the method of crude dehydration + extractive distillation dehydration to replace the original azeotropic distillation process. Crude dehydration, i.e., crude fractionation tower + stripping tower dehydration, can remove about two-thirds of the water with lower energy consumption; the remaining one-third of the water is dehydrated by extractive distillation. The extractive distillation dehydration process has lower energy consumption and higher efficiency than the azeotropic distillation dehydration process.

[0024] 2. The separation system of the high-water-content low-carbon alcohol of the utility model optimizes the heat exchange network of the separation process and greatly reduces the energy consumption, which is specifically embodied in the following aspects: the second extraction from the side line of the coarse separation tower is used to preheat the organic phase of the coarse separation tower phase separation tank (coarse separation single-tower process); the top gas phase of the coarse separation tower 2 is used as a heat source for the steam reboiler of the coarse separation tower 1 (coarse separation double-tower process); the waste water at the bottom of the stripping tower is used to preheat the feed of the stripping tower; the extractant at the bottom of the regeneration tower is used as a heat source for the ethanol tower heat exchange reboiler, and then as a heat source for the coarse separation tower feed preheater; the top gas phase of the propanol tower is used as a heat source for the methanol tower heat exchange reboiler; the top gas phase of the n-butanol tower is used as a heat source for the methanol tower heat exchange reboiler; the steam condensate is used as a heat source for the isopropanol tower steam reboiler; and the steam condensate is used as a heat source for the ethanol tower steam reboiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the separation system diagram of Example 1:

[0026] Figure 2 This is the separation system diagram of Example 3:

[0027] 1-coarse separation tower 1; 2-coarse separation tower steam reboiler; 3-coarse separation tower condenser; 4-feedstock preheater; 5-coarse separation tower heat exchange cooler; 6-coarse separation tower circulating water cooler; 7-coarse separation tower phase separation tank; 8-stripping tower; 9-stripping tower steam reboiler; 10-stripping tower condenser; 11-stripping tower feed preheater; 12-extraction tower; 13-extraction tower steam reboiler; 14-extraction tower condenser; 15-regeneration tower; 16-regeneration tower steam reboiler; 17-regeneration tower condenser; 18-methanol tower; 19-methanol tower steam reboiler; 20-methanol tower heat exchange reboiler 1; 21-methanol tower reboiler Hot reboiler 2; 22-methanol tower condenser; 23-ethanol tower; 24-ethanol tower steam reboiler; 25-ethanol tower hot water reboiler; 26-ethanol tower heat exchange reboiler; 27-ethanol tower condenser; 28-isopropanol tower; 29-isopropanol tower steam reboiler; 30-isopropanol tower hot water reboiler; 31-isopropanol tower condenser; 32-n-propanol tower; 33-n-propanol tower reboiler; 34-n-butanol tower; 35-n-butanol tower reboiler, 36-coarse fractionation tower 1 heat exchange reboiler, 37-coarse fractionation tower 2; 38-coarse fractionation tower 2 reboiler, 39-coarse fractionation tower 2 condenser; 40-coarse fractionation tower 2 reflux phase separation tank. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely illustrative and non-restrictive, and should not be used to limit the scope of protection of the present invention.

[0029] Example 1 (single tower system)

[0030] like Figure 1 The separation system of a high-water-content low-carbon alcohol shown in the figure includes a coarse separation tower 1, a coarse separation tower phase separation heat exchange cooler 5, a coarse separation tower circulating water cooler 6, a coarse separation tower phase separation tank 7, a stripping tower 8, a stripping tower feed preheater 11, an extraction tower 12, a regeneration tower 15, a methanol tower 18, an ethanol tower 23, an isopropanol tower 28, an n-propanol tower 32 and an n-butanol tower 34, each tower is equipped with a corresponding reboiler and condenser.

[0031] The crude fraction tower 1 has a raw material inlet, the kettle of the crude fraction tower 1 is equipped with a crude fraction tower steam reboiler 2, a raw material preheater 4 is arranged on the inlet pipeline, the top production pipeline of the crude fraction tower 1 is connected to the crude fraction tower condenser 3, the gas phase outlet of the crude fraction tower condenser 3 is used for discharging non-condensable gas, and the liquid phase outlet pipeline of the crude fraction tower condenser 3 is divided into two routes, one route is connected to the reflux inlet of the crude fraction tower 1, and the other route is used as the methanol product production pipeline. The upper part of the crude fraction tower 1 is provided with a side line, which is connected to the inlet of the extraction tower 12 through a pipeline. The bottom outlet of the extraction tower 12 is connected to the inlet of the regeneration tower 15 through a pipeline. The top gas phase outlet of the regeneration tower 15 is connected to the inlet of the regeneration tower condenser 17 through a pipeline. The outlet pipeline of the regeneration tower condenser 17 is divided into two paths, one is connected to the reflux port of the regeneration tower 15, and the other is connected to the first inlet of the stripping tower 8; the bottom outlet of the regeneration tower 15 passes through the shell side of the ethanol tower heat exchange reboiler 26 (which also serves as an extractant cooler) and the shell side of the raw material preheater 4 through a pipeline to enter the extractant inlet of the extraction tower 12. The top outlet of the extraction tower 12 is connected to the extraction tower condenser 1 through a pipeline. 4, the outlet pipeline of the extraction tower condenser 14 is divided into two paths, one path is connected to the reflux port of the extraction tower 12, and the other path is connected to the inlet of the methanol tower 18. The gas phase production port at the top of the methanol tower 18 is connected to the inlet of the methanol tower condenser 22 through a pipeline. The outlet pipeline of the methanol tower condenser 22 is divided into two paths, one path is connected to the reflux port of the methanol tower 18, and the other path is connected to the external production port. The bottom production port of the methanol tower 18 is connected to the inlet of the ethanol tower 23 through a pipeline, the bottom production port of the ethanol tower 23 is connected to the inlet of the isopropanol tower 28 through a pipeline, the bottom production port of the isopropanol tower 28 is connected to the inlet of the n-propanol tower 32 through a pipeline, and the bottom of the n-propanol tower 32 is the isobutanol product production pipeline. The outlet pipelines of methanol column condenser 22, ethanol column condenser 27, and isopropyl alcohol column condenser 31, respectively installed at the tops of methanol column 18, ethanol column 23, and isopropyl alcohol column 28, are each bifurcated into two routes: one route is connected to the reflux port of methanol column 18, ethanol column 23, and isopropyl alcohol column 28, respectively; the other routes serve as the methanol product extraction pipeline, ethanol product extraction pipeline, and isopropyl alcohol product extraction pipeline, respectively. The overhead gas phase of n-propyl alcohol column 32 is connected via a pipeline to the shell-side inlet of methanol column heat exchange reboiler 21 (which also serves as the n-propyl alcohol column condenser). The shell-side outlet of methanol column heat exchange reboiler 21 (which also serves as the n-propyl alcohol column condenser) is bifurcated into two routes via a pipeline: one route is connected to the reflux port of n-propyl alcohol column 32, and the other route serves as the n-propyl alcohol product extraction pipeline.

[0032] The stripping tower 8 is equipped with a stripping tower steam reboiler 9, and the extraction tower 12 is equipped with an extraction tower steam reboiler 13; the regeneration tower 15 is equipped with a regeneration tower steam reboiler 16, the methanol tower 18 is equipped with a methanol tower steam reboiler 19, a methanol tower heat exchange reboiler 1 20 (also serving as a butanol tower condenser), and a methanol tower heat exchange reboiler 21 (also serving as a n-propanol tower condenser); the ethanol tower 23 is equipped with an ethanol tower steam reboiler 24, an ethanol tower hot water reboiler 25, and an ethanol tower heat exchange reboiler 26 (also serving as an extractant cooler); the isopropanol tower 28 is equipped with an isopropanol tower steam reboiler 29 and an isopropanol tower hot water reboiler 30; the n-propanol tower 32 is equipped with an n-propanol tower reboiler 33, an n-butanol tower 34, and an n-butanol tower reboiler 35.

[0033] The lower part of the coarse fractionation tower 1 is provided with a side line 2, and the extraction pipeline of the side line 2 enters the heat medium inlet of the coarse fractionation tower phase separation heat exchange cooler 5 and the tube side of the coarse fractionation tower circulating water cooler 6 in sequence, and then enters the inlet of the coarse fractionation tower phase separation tank 7, the organic phase outlet of the coarse fractionation tower phase separation tank 7 is connected to the refrigerant inlet of the coarse fractionation tower phase separation heat exchange cooler 5 through a pipeline, the refrigerant outlet of the coarse fractionation tower phase separation heat exchange cooler 5 is connected to the coarse fractionation tower 1 through a pipeline, and the water phase outlet of the coarse fractionation tower phase separation tank 7 is connected to the second inlet of the stripping tower 8 after passing through the tube side of the stripping tower feed preheater 11 through a pipeline; the bottom extraction outlet of the stripping tower 8 enters the shell side of the stripping tower feed preheater 11 through a pipeline and is used as a wastewater discharge pipeline, and the gas phase extraction outlet at the top of the stripping tower 8 is connected to the steam The inlet of the stripping tower condenser 10, the outlet pipeline of the stripping tower condenser 10 is divided into two routes, one is connected to the reflux port of the stripping tower 8, and the other is connected to the inlet of the coarse separation tower phase separation tank 7 after passing through the coarse separation tower circulating water cooler 6; the bottom production outlet of the coarse separation tower 1 is connected to the inlet of the n-butanol tower 34 through a pipeline, and the top gas phase production outlet of the n-butanol tower 34 is connected to the shell side inlet of the methanol tower heat exchange reboiler 20 (also serving as the n-butanol tower condenser) through a pipeline. The shell side outlet pipeline of the methanol tower heat exchange reboiler 20 (also serving as the butanol tower condenser) is divided into two routes, one is connected to the reflux port of the n-butanol tower 34 through a pipeline, and the other is used as the n-butanol product production pipeline. The bottom production pipeline of the n-butanol tower 34 is the heavy alcohol production pipeline.

[0034] Example 2

[0035] A process method for the separation system of high-water-content low-carbon alcohols described in Example 1 comprises: a mixed alcohol feedstock preheated in a feedstock preheater 4 and then fed into a first coarse fractionation tower 1. The feedstock preheater 4 uses a regeneration tower bottom extractant as a heat source. The extractant is selected from one or a mixture of ethylene glycol, 1,3-propylene glycol, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), N-formylmorpholine (NFM), dimethyl sulfoxide (DMSO), and the like. The first coarse fractionation tower 1 is equipped with a reboiler 2 using steam as a heat source. The first coarse fractionation tower is an atmospheric pressure tower with an atmospheric top pressure, a top temperature of 58°C, and a bottom temperature of 130°C. The gas phase at the top of the first coarse fractionation tower 1 enters a first coarse fractionation tower condenser 3 for condensation, and non-condensable gases are discharged. A portion of the condensed liquid is returned to the first coarse fractionation tower 1 as reflux, and a portion is withdrawn as methanol product.

[0036] A mixed solution of methanol, ethanol, propanol, a small amount of butanol and water is produced from the upper side line of the crude fraction tower 1 and sent to the extraction tower 12.

[0037] Two coolers are installed at the lower side of crude fractionator 1, the second side of which is the first side of the crude fractionator. One is the first side of the crude fractionator heat exchange and phase separation cooler 5, which uses the organic phase from the first side of the crude fractionator phase separation tank 7 as the refrigerant; the other is the first side of the crude fractionator circulating water cooler 6, which uses circulating water as the refrigerant. After cooling, the material from the second side of the crude fractionator enters the first side of the crude fractionator phase separation tank 7 for phase separation, with a cooling temperature of 50°C. The organic phase is then heat exchanged in the first side of the crude fractionator phase separation heat exchange cooler 5 and returned to the first side of the crude fractionator. The aqueous phase is preheated and then sent to the stripping tower 8.

[0038] Heavy alcohols such as butanol and pentanol are produced from the bottom of the crude fraction tower 1 and sent to the n-butanol tower 34.

[0039] The material from the coarse fractionation tower phase separation tank 7 is preheated in the stripping tower feed preheater 11 and then sent to the stripping tower 8. The stripping tower feed preheater 11 uses the wastewater extracted from the bottom of the stripping tower 8 as a heat source. The wastewater from the top of the regeneration tower 15 is also sent to the stripping tower 8. The stripping tower 8 is equipped with a reboiler 9, which uses water vapor as a heat source. The stripping tower is a normal pressure tower with a top pressure of normal pressure, a top temperature of 92°C, and a bottom temperature of 100°C. The gas phase at the top of the stripping tower 8 enters the stripping tower condenser 10 for condensation. Part of the condensed liquid returns to the stripping tower 8 as reflux, and part is extracted to the coarse fractionation tower phase separation tank 7 for phase separation. The wastewater extracted from the bottom of the stripping tower 8 is cooled in the stripping tower feed preheater 11 and then discharged.

[0040] The material from the side line of crude fractionation tower 1 is fed to the middle of extraction tower 12. The extractant is added from the upper middle portion of extraction tower 12. Extraction tower 12 is equipped with a reboiler 13 using steam as a heat source. Extraction tower 12 is a vacuum tower with a top pressure of -55 kPa, a top temperature of 58°C, and a bottom temperature of 146°C. The gas phase at the top of extraction tower 12 enters extraction tower condenser 14 for condensation. Part of the condensed liquid is returned to extraction tower 12 as reflux, and part is withdrawn to methanol tower 18.

[0041] The material at the bottom of the extraction tower 12 is sent to the regeneration tower 15, which is equipped with a regeneration tower steam reboiler 16 with water vapor as the heat source; the regeneration tower 15 is a vacuum tower with a top pressure of -85kPa, a top temperature of 54°C, and a bottom temperature of 154°C; the gas phase at the top of the regeneration tower 15 enters the regeneration tower condenser 17 for condensation, and part of the condensed liquid is returned to the regeneration tower 15 as reflux, and part is withdrawn as wastewater to the stripping tower 8 for stripping; the extractant at the bottom of the regeneration tower 15 passes through the ethanol tower heat exchange reboiler 26 (extractant cooler) and the raw material preheater 4 in sequence for heat exchange and then returns to the extraction tower 12 for recycling.

[0042] The material from the top of extraction tower 12 is fed to methanol tower 18, which is equipped with three reboilers: a methanol tower steam reboiler 19, which uses water vapor as its heat source; a methanol tower heat exchange reboiler 1 20 (butanol tower condenser), which uses the overhead vapor from n-butanol tower 34 as its heat source; and a methanol tower heat exchange reboiler 2 21 (which also serves as the n-propanol tower condenser), which uses the overhead vapor from n-propanol tower 32 as its heat source. Methanol tower 18 is an atmospheric tower with an atmospheric top pressure, a top temperature of 63°C, and a bottom temperature of 85°C. The overhead vapor from methanol tower 18 enters methanol tower condenser 22 for condensation. The condensed liquid is partially returned to methanol tower 18 as reflux, and partially withdrawn as methanol product.

[0043] The bottoms of methanol tower 18 are fed to ethanol tower 23, which is equipped with three reboilers: a steam reboiler 24, which uses steam as its heat source; a hot water reboiler 25, which uses steam condensate as its heat source; and a heat exchange reboiler 26, which also serves as an extractant cooler, using the extractant at the bottom of extraction tower 12 as its heat source. Ethanol tower 23 is a negative pressure tower with a top pressure of -60 kPa, a top temperature of 56°C, and a bottom temperature of 81°C. The overhead gas from ethanol tower 23 enters ethanol tower condenser 27 for condensation. The condensed liquid is partially returned to ethanol tower 23 as reflux, and partially withdrawn as ethanol product.

[0044] The bottoms of ethanol tower 23 are fed to isopropyl alcohol tower 28, which is equipped with two reboilers: a steam reboiler 29, which uses steam as its heat source, and a hot water reboiler 30, which uses condensed steam as its heat source. Isopropyl alcohol tower 28 operates at atmospheric pressure, with a top temperature of 83°C and a bottom temperature of 103°C. The vapor from the top of isopropyl alcohol tower 28 enters condenser 31 for condensation. The condensed liquid is partially returned to isopropyl alcohol tower 28 as reflux, and partially withdrawn as isopropyl alcohol product.

[0045] The bottoms of isopropyl alcohol column 28 are fed to n-propyl alcohol column 32, which is equipped with a reboiler 33 using steam as a heat source. n-propyl alcohol column 32 is an atmospheric pressure column with a top pressure of atmospheric pressure, a top temperature of 99°C, and a bottom temperature of 117°C. The vapor from the top of n-propyl alcohol column 32 enters the methanol column heat exchange reboiler 21 (which also serves as the n-propyl alcohol column condenser) for condensation. A portion of the condensed liquid is returned to n-propyl alcohol column 32 as reflux, while a portion is withdrawn as n-propyl alcohol product. The isobutanol product is withdrawn from the bottom of n-propyl alcohol column 32.

[0046] The material from the bottom of crude fraction tower 1 is fed to n-butanol tower 34, which is equipped with a reboiler 35 using steam as its heat source. n-butanol tower 34 is an atmospheric tower with atmospheric pressure, a top temperature of 120°C, and a bottom temperature of 141°C. The vapor from the top of n-butanol tower 34 enters the methanol tower heat exchange reboiler 20 (which also serves as the n-butanol tower condenser) for condensation. Part of the condensed liquid is returned to n-butanol tower 34 as reflux, while part is withdrawn as n-butanol product. Heavy alcohol product is withdrawn from the bottom of n-butanol tower 34.

[0047] Example 3 (double tower system)

[0048] like Figure 2The separation system shown in the figure differs from that of Example 1 only in that it further includes a coarse separation tower 37, a coarse separation tower steam reboiler 38, a coarse separation tower condenser 39, and a coarse separation tower reflux phase separation tank 40. The coarse separation tower 1 is equipped with two reboilers, a coarse separation tower heat exchange reboiler 36 (also serving as a coarse separation tower condenser) and a coarse separation tower steam reboiler 2. The coarse separation tower phase separation tank 7 is installed at the bottom of the tower. The extraction pipeline at the bottom of the coarse separation tower 1 is divided into two routes, one of which is connected to the coarse separation tower 2. The inlet of tower 37, the other one passes through the heat medium inlet and heat medium outlet of the phase-separation heat exchange cooler 5 of the coarse separation tower 1, enters the pipe side of the circulating water cooler 6 of the coarse separation tower 1, and is connected to the inlet of the phase-separation tank 7 of the coarse separation tower 1 through a pipeline. The organic phase extraction pipeline of the phase-separation tank 7 of the coarse separation tower 1 passes through the refrigerant inlet and refrigerant outlet of the phase-separation heat exchange cooler 5 of the coarse separation tower 1, and is connected to the inlet of the coarse separation tower 2 37. The water phase is connected to the first inlet of the stripping tower 8 through the extraction pipeline; the coarse separation tower 2 37 The bottom outlet of the tower is connected to the inlet of the n-butanol tower 34 through a pipeline, the top gas phase outlet of the crude separation tower 37 is connected to the shell side inlet of the heat exchange reboiler 36 of the crude separation tower 1 (which also serves as the condenser of the crude separation tower 2) through a pipeline, the shell side outlet of the heat exchange reboiler 36 of the crude separation tower 1 is connected to the inlet of the reflux phase separation tank 40 of the crude separation tower 2 through a pipeline of the condenser 39 of the crude separation tower 2, and the organic phase outlet of the reflux phase separation tank 40 of the crude separation tower 2 is connected to the top of the crude separation tower 37 through a pipeline. The reflux port, the water phase outlet of the coarse separation tower 1 phase separation tank 7 and the coarse separation tower 2 reflux phase separation tank 40 are all connected to the first inlet of the stripping tower 8 through a pipeline after passing through the stripping tower feed preheater 11. The top outlet of the stripping tower 8 is connected to the inlet of the stripping tower condenser 10 through a pipeline. The outlet pipeline of the stripping tower condenser 10 is divided into two routes, one is connected to the reflux port of the stripping tower 8, and the other is connected to the inlet of the coarse separation tower 2 reflux phase separation tank 40 through the coarse separation tower 2 condenser 39 through a pipeline.

[0049] Example 4

[0050] A process method for the separation system of high-water-content low-carbon alcohols described in Example 3: The mixed alcohol feedstock is preheated in a feedstock preheater 4 and then fed into a coarse fractionation tower 1. The feedstock preheater 4 uses the extractant at the bottom of the regeneration tower 15 as a heat source. The coarse fractionation tower 1 is equipped with two reboilers: one is a coarse fractionation tower 1 steam reboiler 2, which uses water vapor as a heat source; the other is a coarse fractionation tower 1 heat exchange reboiler 36, which uses the overhead gas phase of the coarse fractionation tower 2 37 as a heat source. The coarse fractionation tower 1 is a normal pressure tower with a top pressure of normal pressure, a top temperature of 58°C, and a bottom temperature of 96°C. The overhead gas phase of the coarse fractionation tower 1 enters the coarse fractionation tower 1 condenser 3 for condensation, and the non-condensable gas is discharged. A portion of the condensed liquid is returned to the coarse fractionation tower 1 as reflux, and a portion is withdrawn as methanol product.

[0051] A mixed solution of methanol, ethanol, propanol, a small amount of butanol and water is taken out from the side line of the crude fraction tower 1 and sent to the extraction tower 12.

[0052] The material extraction pipeline at the bottom of crude fraction tower 1 is equipped with two coolers: one is a phase-separation heat exchange cooler 5 at the bottom of crude fraction tower 1, using the organic phase from crude fraction tower 1 phase separation tank 7 as the refrigerant; the other is a phase-separation circulating water cooler 6 at the bottom of crude fraction tower 1, using circulating water as the refrigerant. The material extracted from the bottom of crude fraction tower 1 is cooled and then enters phase separation tank 7 of crude fraction tower 1 for phase separation. The cooling temperature is 50°C. The organic phase is then heat exchanged in phase-separation heat exchange cooler 5 and delivered to the inlet of crude fraction tower 2 37.

[0053] The material at the bottom of the first crude fraction tower 1 can also be sent directly to the second crude fraction tower 37 without passing through the phase separation tank 8 at the bottom of the first crude fraction tower. The second crude fraction tower 37 is equipped with a steam reboiler 38 for the second crude fraction tower, which uses water vapor as the heat source. The second crude fraction tower 37 is a pressurized tower with a top pressure of 150kPa, a top temperature of 118°C, and a bottom temperature of 152°C. The gas phase at the top of the second crude fraction tower 37 enters the heat exchange reboiler 36 of the first crude fraction tower for condensation. The condensed liquid is cooled by the condenser 39 of the second crude fraction tower and then enters the reflux phase separation tank 40 of the second crude fraction tower for phase separation. The organic phase returns to the top of the second crude fraction tower 37. Heavy alcohols such as butanol and pentanol are extracted from the bottom of the second crude fraction tower 37 and sent to the n-butanol tower 34.

[0054] The material from the phase separation tank 7 of the first coarse fractionation tower and the water phase from the reflux phase separation tank 40 of the second coarse fractionation tower are preheated in the stripping tower feed preheater 11 and sent to the stripping tower 8. The stripping tower feed preheater 11 uses the wastewater extracted from the bottom of the stripping tower 8 as a heat source. The wastewater from the top of the regeneration tower 15 is also sent to the stripping tower 8. The stripping tower 8 is equipped with a stripping tower steam reboiler 9, which uses water vapor as a heat source. The stripping tower 8 is a normal pressure tower with a top pressure of normal pressure, a top temperature of 91°C, and a bottom temperature of 100°C. The gas phase at the top of the stripping tower 8 enters the stripping tower condenser 10 for condensation. Part of the condensed liquid returns to the stripping tower 8 as reflux, and part is extracted to the reflux phase separation tank 40 of the second coarse fractionation tower for phase separation. The wastewater extracted from the bottom of the stripping tower 8 is cooled by the stripping tower feed preheater 11 and then discharged.

[0055] The material from the side line of the crude fractionator 1 is fed to the middle of the extraction tower 12. The extractant is added from the upper middle portion of the extraction tower 12. The extraction tower 12 is equipped with a steam reboiler 13, which uses water vapor as a heat source. The extraction tower 12 is a vacuum tower with a top pressure of -55 kPa, a top temperature of 58°C, and a bottom temperature of 146°C. The gas phase at the top of the extraction tower 12 enters the extraction tower condenser 14 for condensation. Part of the condensed liquid is returned to the extraction tower 12 as reflux, and part is withdrawn to the methanol tower 18.

[0056] The material at the bottom of the extraction tower 12 is sent to the regeneration tower 15, which is equipped with a regeneration tower steam reboiler 16 with water vapor as the heat source; the regeneration tower 15 is a vacuum tower with a top pressure of -85kPa, a top temperature of 54°C, and a bottom temperature of 154°C; the gas phase at the top of the regeneration tower 15 enters the regeneration tower condenser 17 for condensation, and part of the condensed liquid is returned to the regeneration tower 15 as reflux, and part is withdrawn as wastewater to the stripping tower 8 for stripping; the extractant at the bottom of the regeneration tower 15 passes through the ethanol tower heat exchange reboiler 26 (which also serves as an extractant cooler) and the raw material preheater 4 in sequence for heat exchange and then returns to the extraction tower 12 for recycling.

[0057] The material from the top of extraction tower 12 is fed to methanol tower 18, which is equipped with three reboilers: a methanol tower steam reboiler 19, which uses water vapor as its heat source; a methanol tower heat exchange reboiler 1 20 (which also serves as the butanol tower condenser), which uses the vapor from the top of n-butanol 34 as its heat source; and a methanol tower heat exchange reboiler 21 21 (which also serves as the n-propanol tower condenser), which uses the vapor from the top of n-propanol 32 as its heat source. Methanol tower 18 is an atmospheric tower with atmospheric pressure, a top temperature of 63°C, and a bottom temperature of 85°C. The vapor from the top of methanol tower 18 enters methanol tower condenser 22 for condensation. The condensed liquid is partially returned to methanol tower 18 as reflux, and partially withdrawn as methanol product.

[0058] The bottoms of methanol tower 18 are fed to ethanol tower 23, which is equipped with three reboilers: a steam reboiler 24, which uses steam as its heat source; a hot water reboiler 25, which uses steam condensate as its heat source; and a heat exchange reboiler 26, which also serves as an extractant cooler, using the extractant at the bottom of extraction tower 12 as its heat source. Ethanol tower 23 is a negative pressure tower with a top pressure of -60 kPa, a top temperature of 56°C, and a bottom temperature of 81°C. The overhead gas from ethanol tower 23 enters ethanol tower condenser 27 for condensation. The condensed liquid is partially returned to ethanol tower 23 as reflux, and partially withdrawn as ethanol product.

[0059] The bottoms of ethanol tower 23 are fed to isopropyl alcohol tower 28, which is equipped with two reboilers: a steam reboiler 29, which uses steam as its heat source, and a hot water reboiler 30, which uses condensed steam as its heat source. Isopropyl alcohol tower 28 operates at atmospheric pressure, with a top temperature of 83°C and a bottom temperature of 103°C. The vapor from the top of isopropyl alcohol tower 28 enters condenser 31 for condensation. The condensed liquid is partially returned to isopropyl alcohol tower 28 as reflux, and partially withdrawn as isopropyl alcohol product.

[0060] The bottoms of isopropyl alcohol column 28 are fed to n-propyl alcohol column 32, which is equipped with a steam reboiler 33 using steam as its heat source. n-propyl alcohol column 32 is an atmospheric pressure column with a top pressure of atmospheric pressure, a top temperature of 99°C, and a bottom temperature of 117°C. The vapor from the top of n-propyl alcohol column 32 enters the methanol column heat exchange reboiler 21 (which also serves as the n-propyl alcohol column condenser) for condensation. A portion of the condensed liquid is returned to n-propyl alcohol column 32 as reflux, while a portion is withdrawn as n-propyl alcohol product. The isobutanol product is withdrawn from the bottom of n-propyl alcohol column 32.

[0061] The material from the bottom of crude fractionation tower 37 is fed to n-butanol tower 34, which is equipped with a steam reboiler 35 using steam as its heat source. n-butanol tower 34 is an atmospheric tower with atmospheric pressure, a top temperature of 120°C, and a bottom temperature of 141°C. The vapor from the top of n-butanol tower 34 enters the methanol tower heat exchange reboiler 20 (which also serves as the butanol tower condenser) for condensation. Part of the condensed liquid is returned to n-butanol tower 34 as reflux, while part is withdrawn as n-butanol product. Heavy alcohol product is withdrawn from the bottom of n-butanol tower 34.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all fall within the scope of protection of the present invention.

Claims

1. A separation system for high-water-content low-carbon alcohols, characterized in that: The invention comprises a coarse fractionation tower (1), a coarse fractionation tower heat exchange cooler (5), a coarse fractionation tower circulating water cooler (6), a coarse fractionation tower phase separation tank (7), a stripping tower (8), a stripping tower feed preheater (11), an extraction tower (12), a regeneration tower (15), a methanol tower (18), an ethanol tower (23), an isopropanol tower (28), a n-propanol tower (32) and a n-butanol tower (34), each tower being equipped with a corresponding reboiler and a condenser. The coarse fractionation tower (1) has a raw material inlet, and a raw material preheater (4) is arranged on the inlet pipeline. The upper part of the coarse fractionation tower (1) has a side line 1, which is connected to the inlet of the extraction tower (12) through a pipeline. The bottom outlet of the extraction tower (12) is connected to the inlet of the regeneration tower (15) through a pipeline. The regeneration tower (15) is connected to the inlet of the regeneration tower (15). The top gas phase outlet of the tower (5) is connected to the inlet of the regeneration tower condenser (17) through a pipeline, and the outlet pipeline of the regeneration tower condenser (17) is divided into two paths, one of which is connected to the reflux port of the regeneration tower (15) and the other is connected to the first inlet of the stripping tower (8); the bottom outlet of the regeneration tower (15) passes through the ethanol tower heat exchange reboiler (26) and the raw material preheater (4) in sequence through the pipeline to enter the extractant inlet of the extraction tower (12), and the top outlet of the extraction tower (12) passes through the extraction tower condenser (14) through the pipeline and is divided into two paths, one of which is connected to the reflux port of the extraction tower (12) and the other is connected to the inlet of the methanol tower (18), and the methanol tower (18) is equipped with a methanol tower steam reboiler (19), a methanol tower heat exchange reboiler (20), a methanol tower The heat exchange reboiler 2 (21) is connected to the bottom outlet of the methanol tower (18) through a pipeline to the inlet of the ethanol tower (23), the bottom outlet of the ethanol tower (23) is connected to the inlet of the isopropyl alcohol tower (28) through a pipeline, the bottom outlet of the isopropyl alcohol tower (28) is connected to the inlet of the n-propanol tower (32) through a pipeline, the bottom of the n-propanol tower (32) is the isobutyl alcohol product extraction pipeline, the top gas phase pipeline of the n-propanol tower (32) is divided into two paths after passing through the heat exchange reboiler 2 (21) of the methanol tower, one path is connected to the reflux port of the n-propanol tower (32), and the other path is used as the n-propanol product extraction pipeline; the lower part of the crude fraction tower (1) is provided with a side line 2, the side line 2 passes through the crude fraction tower heat exchange cooler (5) and the crude fraction tower circulating water cooler (6) through a pipeline, and then Entering the phase separation tank (7) of the coarse fractionation tower (7), the organic phase outlet of the phase separation tank (7) of the coarse fractionation tower (7) is connected to the inlet of the coarse fractionation tower (1) through a pipeline through the heat exchange cooler (5) of the coarse fractionation tower (1), and the water phase outlet of the phase separation tank (7) of the coarse fractionation tower (7) is connected to the second inlet of the stripping tower (8) through a pipeline through the stripping tower feed preheater (11); the bottom outlet of the stripping tower (8) is connected to the stripping tower feed preheater (11) through a pipeline and serves as a wastewater discharge pipeline, and the gas phase outlet of the top of the stripping tower (8) is connected to the inlet of the stripping tower condenser (10) through a pipeline, and the outlet pipeline of the stripping tower condenser (10) is divided into two routes, one route is connected to the reflux port, and the other route is connected to the inlet of the phase separation tank (7) of the coarse fractionation tower (7) after passing through the circulating water cooler (6) of the coarse fractionation tower (10);The bottom extraction outlet of the crude fraction tower (1) is connected to the inlet of the n-butanol tower (34) through a pipeline. The top gas phase extraction pipeline of the n-butanol tower (34) is divided into two routes after passing through the methanol tower heat exchange reboiler (20). One route is connected to the reflux port of the n-butanol tower (34) through a pipeline, and the other route is used as the n-butanol product extraction pipeline. The bottom extraction pipeline of the n-butanol tower (34) is the heavy alcohol extraction pipeline.

2. The separation system of high water content low carbon alcohol according to claim 1, characterized in that: The invention also includes a coarse separation tower (37), a coarse separation tower steam reboiler (38), a coarse separation tower condenser (39), and a coarse separation tower reflux phase separation tank (40). The coarse separation tower (1) is equipped with a coarse separation tower heat exchange reboiler (36) and a coarse separation tower steam reboiler (2). The coarse separation tower phase separation tank (7) is installed at the bottom of the coarse separation tower (1). The bottom extraction pipeline of the coarse separation tower (1) is divided into two routes, one of which is directly connected to the inlet of the coarse separation tower (37), and the other is connected to the inlet of the coarse separation tower (37) after passing through the coarse separation tower phase separation tank (7) and the coarse separation tower phase separation heat exchange cooler (5). The bottom extraction outlet of the coarse separation tower (37) is connected to the inlet of the n-butanol tower (34) through a pipeline. The gas phase extraction pipeline at the top of the coarse separation tower (37) passes through the coarse separation tower (37) in sequence. The heat exchange reboiler (36) of the first coarse separation tower and the condenser (39) of the second coarse separation tower are connected to the inlet of the reflux phase separation tank (40) of the second coarse separation tower. The organic phase extraction port of the reflux phase separation tank (40) of the second coarse separation tower is connected to the top reflux port of the second coarse separation tower (37) through a pipeline. The water phase extraction ports of the first coarse separation tower phase separation tank (7) and the reflux phase separation tank (40) of the second coarse separation tower are connected to the first inlet of the stripping tower (8) through a pipeline after passing through the stripping tower feed preheater (11). The top extraction port of the stripping tower (8) is connected to the inlet of the stripping tower condenser (10) through a pipeline. The outlet pipeline of the stripping tower condenser (10) is divided into two routes, one route is connected to the reflux port of the stripping tower (8), and the other route is connected to the inlet of the reflux phase separation tank (40) of the second coarse separation tower after passing through the condenser (39) of the second coarse separation tower.

3. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The top extraction pipeline of the crude fraction tower (1) is connected to the crude fraction tower condenser (3), the gas phase outlet of the crude fraction tower condenser (3) is used for discharging non-condensable gas, and the liquid phase outlet pipeline of the crude fraction tower condenser (3) is divided into two routes, one route is connected to the reflux inlet of the crude fraction tower (1), and the other route is used as a methanol product extraction pipeline.

4. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The outlet pipelines of the methanol tower condenser (22), ethanol tower condenser (27) and isopropanol tower condenser (31) respectively equipped on the top of the methanol tower (18), ethanol tower (23) and isopropanol tower (28) are divided into two paths, one path is connected to the reflux port of the methanol tower (18), ethanol tower (23) and isopropanol tower (28), and the other path is used as a methanol product extraction pipeline, an ethanol product extraction pipeline and an isopropanol product extraction pipeline.

5. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The stripping tower (8), methanol tower (18), isopropanol tower (28), n-propanol tower (32), and n-butanol tower (34) are all atmospheric pressure towers.

6. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The extraction tower (12) and the regeneration tower (15) are vacuum towers.

7. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The ethanol tower (23) is a negative pressure tower.

8. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The methanol tower (18) is equipped with three reboilers, one being a methanol tower steam reboiler (19) using water vapor as a heat source, one being a methanol tower heat exchange reboiler 1 (20) using the top gas phase of the n-butanol tower (34) as a heat source, and one being a methanol tower heat exchange reboiler 2 (21) using the top gas phase of the n-propanol tower (32) as a heat source.

9. The separation system of high water content low carbon alcohol according to claim 1 or 2, characterized in that: The ethanol tower (23) is equipped with three reboilers, one is an ethanol tower steam reboiler (24), which uses water vapor as a heat source; one is an ethanol tower hot water reboiler (25), which uses steam condensed water as a heat source; and another is an ethanol tower heat exchange reboiler (26), which uses the extractant at the bottom of the extraction tower (12) as a heat source.

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