CN-121988054-A - Ethanol upgrading device and method

CN121988054ACN 121988054 ACN121988054 ACN 121988054ACN-121988054-A

Abstract

The invention relates to an ethanol quality-improving device and method, which are used for improving quality of ethanol containing a small amount of ethyl acetate, wherein the device comprises a low-pressure rectifying unit, a pumping unit and a high-pressure rectifying unit which are sequentially connected, adopts the principle of pressure-variable rectification, changes azeotrope composition only by a pressure-variable mode, is matched with reasonable process parameters, extracts ethanol after purification by the low-pressure rectifying unit, extracts ethanol with higher ethyl acetate content by the high-pressure rectifying unit, avoids evaporating a large amount of ethanol to the high-pressure rectifying unit, obviously reduces energy consumption, lowers production cost and improves economic benefit.

Inventors

SHAN SIZHEN
LIU CHUANG
CHEN XIAOMIN
SHEN CHANGLIN
LI XUAN
LIU SHIYU
He Tichang
Huang Mafu
HU XIANNIAN

Assignees

惠州博科环保新材料有限公司
惠州宇新新材料有限公司

Dates

Publication Date: 20260508
Application Date: 20260331

Claims (10)

1. The ethanol quality improving device is characterized by comprising a low-pressure rectifying unit, a pumping unit and a high-pressure rectifying unit which are sequentially connected, wherein an azeotrope outlet of the low-pressure rectifying unit is connected with an inlet of the high-pressure rectifying unit through a pipeline S1 through the pumping unit, an azeotrope outlet of the high-pressure rectifying unit is connected with a reflux inlet of the low-pressure rectifying unit, purified ethanol is extracted by the low-pressure rectifying unit, and ethanol with higher ethyl acetate content is extracted by the high-pressure rectifying unit.
2. The ethanol quality improving device according to claim 1, wherein the low-pressure rectifying unit comprises a low-pressure tower, a low-pressure tower reboiler, a low-pressure tower top condenser and a low-pressure tower reflux tank, a material inlet of the low-pressure tower is connected with a material inlet pipeline S2, a material outlet at the bottom of the low-pressure tower is divided into two paths through pipelines, one path is connected with the low-pressure tower reboiler, the other path is a purified ethanol extraction pipeline S3, the material outlet at the top of the low-pressure tower is sequentially connected with the low-pressure tower top condenser and the low-pressure tower reflux tank, an outlet of the low-pressure tower reflux tank is divided into two paths through pipelines, one path is connected with a reflux inlet of the low-pressure tower, and the other path is connected with the pumping unit.
3. The ethanol quality improving device according to claim 2, wherein the high-pressure rectifying unit comprises a high-pressure tower, a high-pressure tower reboiler, a high-pressure tower top condenser and a high-pressure tower reflux tank, wherein a feed inlet of the high-pressure tower is connected with a pipeline S1, a bottom discharge outlet of the high-pressure tower is divided into two paths through the pipeline, one path is connected with the high-pressure tower reboiler, the other path is an ethanol extraction pipeline S4 with higher ethyl acetate content, the top discharge outlet of the high-pressure tower is sequentially connected with the high-pressure tower top condenser and the high-pressure tower reflux tank, an outlet of the high-pressure tower reflux tank is divided into two paths through the pipeline, one path is connected with a reflux inlet of the high-pressure tower, and the other path is connected with a reflux inlet of the low-pressure rectifying unit.
4. The ethanol upgrading apparatus according to claim 3, wherein the theoretical plate number of the low-pressure column is 60, the feed plate number is 30, the theoretical plate number of the high-pressure column is 28, and the feed plate number is 9.
5. The ethanol upgrading apparatus according to any one of claims 2-4, wherein the purified ethanol extraction line S3 is provided with a low pressure bottom pump.
6. The ethanol upgrading device according to any one of claims 3-4, wherein a high-pressure bottom pump is arranged on the ethanol extraction pipeline S4 with higher ethyl acetate content.
7. The ethanol upgrading apparatus according to any one of claims 3-4, wherein a higher pressure column reflux pump is provided on the line S5.
8. The ethanol upgrading device according to claim 1, wherein the pumping unit is a booster pump.
9. A method of upgrading ethanol using the ethanol upgrading apparatus of claim 4, comprising the steps of: (1) Ethanol containing impurity ethyl acetate enters a low-pressure tower through a pipeline S2, the tower top pressure of the low-pressure tower is controlled to be 40-110kPaA, the tower top temperature is controlled to be 53-77 ℃, part of the condensed tower top azeotrope flows back, the reflux amount is 1.2-1.5 times of the feeding amount of the low-pressure tower, the other part of the condensed tower top azeotrope enters a high-pressure tower through a pipeline S1, and ethanol from which ethyl acetate is removed is extracted from the bottom of the low-pressure tower through a pipeline S3; (2) The top pressure of the high-pressure tower is controlled to be 800-1000kPaG, the temperature of the top of the tower is 146-153 ℃, part of the tower top azeotrope is refluxed after being condensed, the reflux quantity is 0.4-1 times of the feeding quantity of the low-pressure tower, the other part of the reflux quantity enters the low-pressure tower through a pipeline S5, and ethanol with higher ethyl acetate content is extracted from the bottom of the high-pressure tower through a pipeline S4.
10. Use of an ethanol upgrading device according to any one of claims 1-8 or a method according to claim 9 for ethanol upgrading.

Description

Ethanol upgrading device and method Technical Field The invention relates to the technical field of chemical industry, in particular to an ethanol upgrading device and method. Background In the process of preparing ethanol by hydrogenating ethyl acetate, a small amount of ethyl acetate is contained in an ethanol product, and the difficulty in separating ethanol and ethyl acetate is that the boiling points of the two differ by only 1 ℃, and an azeotropic phenomenon exists, so that the removal of a small amount of ethyl acetate in the ethanol to improve the quality of the ethanol product is a problem to be solved urgently. At present, the main methods for removing ethyl acetate in ethanol include extraction rectification, pressure swing rectification, hydrolysis reaction and the like. The extractive distillation method needs to introduce an extractant, influences the product quality to a certain extent, is complex to operate, and generally has the impurity removal rate of not more than 99.9 percent. The hydrolysis method is only suitable for an aqueous system, and the application range is narrow. In the traditional double-tower pressure-swing rectification process method for separating ethanol and ethyl acetate, a first tower is a pressurizing tower, a tower kettle is used for extracting purified ethyl acetate, a second tower is an atmospheric tower, and the tower kettle is used for extracting purified ethanol. For example, in CN201210481246, double-column pressure-swing rectification is adopted, the mixture of ethanol and ethyl acetate is first fed into the pressure rectifying tower, at this time, the content of ethanol in the azeotrope is high, so that high-purity ethyl acetate is produced in the tower bottom, the azeotrope at the tower top is fed into the normal pressure rectifying tower, the azeotropic ratio is changed, at this time, the content of ethanol in the azeotrope is reduced, so that high-purity ethanol is produced in the tower bottom. The condensate at the two tower tops are used as the feeding material of the other tower for circulating application. Because of the large amount of material circulation in double-tower pressure swing rectification, the overall energy consumption is large. In CN202110514382, energy saving optimization is carried out, and the gas phase of the pressurizing tower directly enters the normal pressure tower, so that the purposes of energy saving and consumption reduction are achieved. However, if this process requires evaporation of a large amount of ethanol from the pressurized tower to the atmospheric tower for a system having a high ethanol content, the energy consumption increases significantly. Accordingly, there is a need for improvements in the art to reduce energy consumption during ethanol upgrading. Disclosure of Invention The invention provides an ethanol quality improving device and method, which are used for improving quality of ethanol containing a small amount of ethyl acetate, the purified ethanol is extracted by a low-pressure rectifying unit, and the ethanol with higher ethyl acetate content is extracted by a high-pressure rectifying unit, so that evaporation of a large amount of ethanol to the high-pressure rectifying unit is avoided, energy consumption is obviously reduced, production cost is reduced, and economic benefit is improved. On the one hand, the invention provides an ethanol quality improving device which comprises a low-pressure rectifying unit, a pumping unit and a high-pressure rectifying unit which are sequentially connected, wherein an azeotrope outlet of the low-pressure rectifying unit is connected with an inlet of the high-pressure rectifying unit through a pipeline S1 by the pumping unit, an azeotrope outlet of the high-pressure rectifying unit is connected with a reflux inlet of the low-pressure rectifying unit, purified ethanol is extracted by the low-pressure rectifying unit, and ethanol with higher ethyl acetate content is extracted by the high-pressure rectifying unit. When the device is used, ethanol containing lower ethyl acetate impurity enters the low-pressure rectification unit, the ethanol is extracted by the low-pressure rectification unit after purification, the azeotrope of the low-pressure rectification unit is sent to the high-pressure rectification unit, the ethanol with higher ethyl acetate content is extracted by the high-pressure rectification unit, and the azeotrope of the high-pressure rectification unit returns to the low-pressure rectification unit for recycling, thereby avoiding evaporating a large amount of ethanol to the high-pressure rectification unit and obviously reducing energy consumption. The low-pressure rectifying unit comprises a low-pressure tower, a low-pressure tower reboiler, a low-pressure tower top condenser and a low-pressure tower reflux tank, wherein a feed inlet of the low-pressure tower is connected with a feed pipeline S2, a discharge outlet at the bottom of the low-pressure tower is