CN215592969U - Separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling - Google Patents

Abstract

The utility model provides a separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling, which comprises a methanol-ethanol staggered thermal coupling cascade separation unit, wherein the methanol-ethanol staggered thermal coupling cascade separation unit is connected with a methyl ester separation unit for separating methanol and methyl ester, and the methyl ester separation unit is connected with an ethyl ester separation unit for separating methanol and ethyl ester; the methanol-ethanol staggered thermal coupling cascade separation unit is also connected with a molecular sieve dehydration unit for separating ethanol and wastewater. According to the utility model, by adopting a differential pressure thermal coupling technology, the ethanol crude product is obtained under the condition of ensuring the lowest energy consumption, meanwhile, the methanol product is recovered to the maximum extent by multi-stage separation, and the methyl acetate and ethyl acetate products are produced.

Description

Separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling

Technical Field

The utility model relates to the technical field of ethanol preparation, in particular to a separation system for preparing ethanol by separating coal through differential pressure thermal coupling.

Background

In the prior art, materials obtained after methanol and ethanol are separated in a coal-to-ethanol separation unit have an azeotropic system of methanol-methyl acetate and methanol-ethyl acetate, the methanol and the methyl acetate and the methanol and the ethyl acetate have azeotropy, and azeotropic compositions formed by different pressures are different, so that the coal-to-ethanol separation unit is a highly non-ideal system.

The boiling point temperature of the system consisting of ethanol and water gradually decreases with the increase of the concentration of ethanol. Under normal pressure, when the ethanol concentration of the ethanol-water mixed solution reaches 95 vol%, the ethanol concentration in the gas phase and the ethanol concentration in the liquid phase are both 95 vol%, and the ethanol-water forms an azeotropic mixture at the concentrations. Therefore, ethanol with a concentration of over 95 vol% cannot be obtained by ordinary distillation.

SUMMERY OF THE UTILITY MODEL

Aiming at the technical problem, the utility model provides a separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling, which is used for solving the problem that high-concentration ethanol cannot be obtained by a rectification method in the prior art.

In order to achieve the purpose, the technical scheme of the utility model is realized as follows:

a separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling comprises a methanol-ethanol staggered thermal coupling cascade separation unit for separating methanol and ethanol, wherein the methanol-ethanol staggered thermal coupling cascade separation unit is connected with a methyl ester separation unit for separating methanol and methyl ester, and the methyl ester separation unit is connected with an ethyl ester separation unit for separating methanol and ethyl ester; the methanol-ethanol staggered thermal coupling cascade separation unit is also connected with a molecular sieve dehydration unit for separating ethanol and wastewater.

Preferably, the methanol-ethanol staggered thermal coupling cascade separation unit comprises a rough separation tower, a methanol tower and an ethanol tower, wherein a tower kettle of the rough separation tower is connected with the methanol tower, and a tower kettle of the methanol tower is connected with the ethanol tower.

Preferably, the methyl ester separation unit comprises a methyl ethyl ester separation tower, a methyl ester pressurizing tower and a methyl ester atmospheric tower, and the top of the rough separation tower is connected with the methyl ethyl ester separation tower; the top of the methyl ethyl ester separation tower is connected with a methyl ester pressurizing tower; the top of the methyl ester pressurizing tower is connected with a methyl ester atmospheric tower.

Preferably, the ethyl ester separation unit comprises an ethyl ester atmospheric tower and an ethyl ester pressurizing tower, and a tower kettle of the ethyl ester separation tower is connected with the ethyl ester atmospheric tower; the top of the ethyl ester atmospheric tower is connected with an ethyl ester pressurizing tower.

Preferably, the molecular sieve dehydration unit comprises a molecular sieve adsorber A, and a side line of the ethanol tower is connected with the molecular sieve adsorber.

Preferably, the device also comprises a recovery tower for recovering the ethanol, and a tower kettle of the ethanol tower is connected with the recovery tower.

Preferably, the device also comprises a light ethanol tower for recovering light ethanol, and the molecular sieve adsorber A is connected with the light ethanol tower.

The utility model has the beneficial effects that:

1. thermal coupling rectification is adopted, so that the steam consumption is saved, the operation stability is highest, and the control is convenient;

2. the efficient separation of azeotropic components is realized by adopting a pressure swing rectification technology;

3. the molecular sieve adsorbs, dehydrates and separates ethanol and water, reduces investment, has low energy consumption and ensures the product quality;

4. the method has the technical characteristics of short flow, safety, reliability, simple equipment structure, convenience in operation and maintenance, full energy utilization, quota consumption and low operation cost.

5. The discharge amount of three wastes is less during normal operation, and strict economic treatment measures are provided. The three wastes discharge and the noise pollution of the contract device are in accordance with the discharge standard promulgated by the government of the people's republic of China.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic flow diagram of the present invention;

fig. 2 is a schematic structural diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 1 and fig. 2, a separation system for separating coal-based ethanol by using differential pressure thermal coupling according to an embodiment of the present invention includes a methanol-ethanol cascade thermal coupling separation unit for separating methanol and ethanol, the methanol-ethanol cascade thermal coupling separation unit is connected to a methyl ester separation unit for separating methyl ester of methanol, and the methyl ester separation unit is connected to an ethyl ester separation unit for separating methyl ester of methanol and ethyl ester; the methanol-ethanol staggered thermal coupling cascade separation unit is also connected with a molecular sieve dehydration unit for separating ethanol and wastewater. The raw material enters an methanol-ethanol staggered thermal coupling cascade separation unit, methanol, mixed ester and an ethanol-water azeotrope are separated, and the ethanol-water azeotrope enters a molecular sieve dehydration unit to produce ethanol and discharge wastewater; the mixed ester enters a methyl ester separation unit to separate methyl acetate and a mixture of ethyl acetate and methanol. And the mixture of the ethyl acetate and the methanol enters an ethyl ester separation unit for separation. Based on physical data analysis and related rectification separation engineering experience, the methanol and the ethanol are separated firstly, so that a process route of preferential methanol-ethanol separation, methanol gradient recovery and ester pressure swing separation is formed, a crude ethanol product is obtained under the condition of ensuring the lowest energy consumption, and meanwhile, a methanol product is recovered to the maximum extent through multi-stage separation, and methyl acetate and ethyl acetate products are obtained.

This application passes through differential pressure thermal coupling technique, divide into a plurality of rectifying columns that pressure is different with the rectifying column, make the top of the tower steam of the higher tower of pressure to the reboiler heat supply of the lower tower of pressure, top of the tower steam is also condensed simultaneously, consequently in differential pressure rectifying column separation process, only the rectifying column that pressure is the highest need add heat (steam), the lower top of the tower steam of pressure condenses with cooling medium, and other each towers do not all need external heat or cooling, with the energy-conserving effect of other overall separation processes. The energy saving effect can be expressed by a formula: the energy-saving effect of the single-tower to double-tower rectification can reach 50 percent, and the energy-saving effect of the triple effect to the quadruple effect is only increased by about 10 percent. Therefore, when the differential pressure thermal coupling rectification is adopted to save energy, the reasonable relation between the saved energy and the increased equipment investment needs to be considered. The differential pressure thermal coupling rectification is generally divided into parallel flow, countercurrent flow and advection according to different flow directions of heating steam and materials, and the specific form is determined according to the operation conditions of an actual material system, so that the effects of saving energy and reducing consumption are fully achieved on the premise of meeting the separation index.

Preferably, the methanol-ethanol staggered thermal coupling cascade separation unit comprises a rough separation tower T1, a methanol tower T2 and an ethanol tower T3, wherein the tower bottom of the rough separation tower T1 is connected with a methanol tower T2, and the tower bottom of the methanol tower T2 is connected with an ethanol tower T3. The raw material firstly enters a rough separation tower T1, a mixture of methyl acetate, ethyl acetate and methanol is extracted from the top of the tower and enters a methyl ester separation unit, and a mixture of methanol, ethanol, a small amount of C3+ fusel and water is extracted from the bottom of the tower. The method comprises the following steps of enabling tower bottom materials of a T1 tower to enter a methanol tower T2, collecting methanol products from the top of a methanol tower T2, enabling latent heat of top steam to provide a heat source for an ethanol tower T3, collecting tower bottom materials such as a mixture of methanol, ethanol, C3+ fusel and water from the bottom of the methanol tower T2 tower, entering an ethanol tower T3, enabling latent heat of the top steam to provide a heat source for a rough separation tower T1, collecting crude ethanol products containing water from the side line of the ethanol tower T3, and collecting a mixture of ethanol and C3 alcohol from the bottom of an ethanol tower T3.

Preferably, a recovery tower T4 for recovering ethanol is further included, and the tower bottom of the ethanol tower T3 is connected with the recovery tower T4. The materials in the bottom of the ethanol tower T3 enter a recovery tower T4, the ethanol yield is improved, the ethanol loss in C3+ alcohol is reduced, the recovered ethanol extracted from the top of the ethanol tower T4 returns to the ethanol tower T3, and high-boiling-point components such as C3 alcohol are extracted from the bottom of the tower.

Preferably, the methyl ester separation unit comprises a methyl ethyl ester separation column T5, a methyl ester pressurizing column T8 and a methyl ester atmospheric column T9, and the top of the crude separation column T1 is connected with a methyl ethyl ester separation column T5; the top of the methyl ethyl ester separation tower T5 is connected with a methyl ester pressurizing tower T8; the top of the methyl ester pressure column T8 was connected to a methyl ester atmospheric column T9. The material at the top of the crude separation tower T1 enters a methyl ethyl ester separation tower T5, a mixture of methyl acetate and methanol is extracted from the top of the methyl ethyl ester separation tower T5, and a mixture of ethyl acetate and methanol is extracted from the bottom of the tower. The material at the top of the methyl ethyl ester separation tower T5 enters a methyl ester pressurizing tower T8, an azeotrope of methyl acetate and methanol under pressure is extracted from the top of the methyl ester pressurizing tower T8, a methyl acetate product is extracted from a side line, and a small amount of mixture containing ethyl acetate is extracted from the bottom of the methyl ester pressurizing tower T8 and returned to the methyl ethyl ester separation tower T5. The material at the top of the methyl ester pressurizing tower T8 enters a methyl ester atmospheric tower T9, an azeotrope of methyl acetate and methanol under normal pressure is extracted from the top of the tower and returned to the methyl ester pressurizing tower T8; the methanol product is extracted from the tower bottom. The methyl ester pressurizing tower T8 and the methyl ester atmospheric tower T9 adopt differential pressure thermal coupling technology, so that the effects of energy conservation and consumption reduction are improved.

Preferably, the ethyl ester separation unit comprises an ethyl ester atmospheric tower T6 and an ethyl ester pressurizing tower T7, and the tower bottom of the ethyl ester separation tower T5 is connected with an ethyl ester atmospheric tower T6; the top of the ethyl ester atmospheric column T6 was connected to an ethyl ester pressure column T7. The tower bottom material of the ethyl methyl separating tower T5 enters an ethyl ester atmospheric tower T6, an azeotrope of ethyl acetate and methanol under normal pressure is extracted from the top of an ethyl ester atmospheric tower T6, a methanol product is extracted from a side line, a mixture containing a small amount of methanol and ethanol is extracted from the tower bottom, and the mixture returns to a methanol tower T2. Feeding the material at the top of the ethyl ester atmospheric tower T6 into an ethyl ester pressurizing tower T7, extracting an azeotrope of ethyl acetate and methanol under pressurization from the top of the tower, returning the azeotrope to the ethyl ester atmospheric tower T6, and providing a heat source for the material steam at the top of the tower to the ethyl ester atmospheric tower T6; the ethyl acetate product is extracted from the side line, and the high-boiling residues are periodically discharged from the tower bottom. The ethyl ester atmospheric tower T6 and the ethyl ester pressurizing tower T7 adopt a differential pressure thermal coupling technology, so that the effects of energy conservation and consumption reduction are improved.

Preferably, the molecular sieve dehydration unit comprises a molecular sieve adsorber a1, and a side line of the ethanol column T3 is connected with the molecular sieve adsorber a 1. And (3) feeding the material collected from the side line of the ethanol tower T3 into a molecular sieve adsorber A1, and condensing to obtain an absolute ethanol product.

Preferably, the device also comprises a light ethanol tower T10 for recovering light ethanol, and the molecular sieve adsorber A1 is connected with the light ethanol tower T10. And (3) enabling the light ethanol desorbed by the molecular sieve of the molecular sieve adsorber A1 to enter a light ethanol tower T-410, returning the recovered ethanol to the molecular sieve adsorber A1 again, and discharging wastewater from the tower bottom.

This application adopts the vary voltage rectification technique according to this characteristic that the azeotropic composition of azeotrope is more sensitive to pressure variation, adopt 2 rectifying columns that operating pressure is different to establish ties promptly and realize azeotrope separation, make the azeotropic raw materials under the ordinary pressure get into first rectifying column (pressurization or decompression) and separate, the tower cauldron obtains pure component 1, the azeotropic composition under corresponding pressure is obtained at the top of the tower, get into second rectifying column (ordinary pressure), obtain the azeotropic composition under corresponding pressure at the top of the tower, this azeotrope returns to first rectifying column feeding, the tower cauldron obtains pure component 2.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (7)

1. A separation system for separating coal-to-ethanol by adopting differential pressure thermal coupling is characterized by comprising a methanol-ethanol staggered thermal coupling cascade separation unit for separating methanol and ethanol, wherein the methanol-ethanol staggered thermal coupling cascade separation unit is connected with a methyl ester separation unit for separating methyl ester of methanol, and the methyl ester separation unit is connected with an ethyl ester separation unit for separating methanol and ethyl ester; the methanol-ethanol staggered thermal coupling cascade separation unit is also connected with a molecular sieve dehydration unit for separating ethanol and wastewater.

2. The separation system for thermally coupling and separating coal-based ethanol by adopting pressure difference as claimed in claim 1, wherein the methanol-ethanol staggered thermal coupling step separation unit comprises a rough separation tower (T1), a methanol tower (T2) and an ethanol tower (T3), wherein the tower bottom of the rough separation tower (T1) is connected with the methanol tower (T2), and the tower bottom of the methanol tower (T2) is connected with the ethanol tower (T3).

3. The separation system for thermally coupling and separating coal-based ethanol by using pressure difference according to claim 2, wherein the methyl ester separation unit comprises a methyl ethyl ester separation tower (T5), a methyl ester pressurizing tower (T8) and a methyl ester atmospheric tower (T9), and the top of the crude separation tower (T1) is connected with the methyl ethyl ester separation tower (T5); the top of the methyl ethyl ester separation column (T5) is connected with a methyl ester pressurizing column (T8); the top of the methyl ester pressure column (T8) was connected to a methyl ester atmospheric column (T9).

4. The separation system for thermally coupling and separating coal-based ethanol by using pressure difference as claimed in claim 3, wherein the ethyl ester separation unit comprises an ethyl ester atmospheric tower (T6), an ethyl ester pressurized tower (T7), and a tower kettle of the ethyl ester separation tower (T5) is connected with the ethyl ester atmospheric tower (T6); the top of the ethyl ester atmospheric column (T6) was connected to an ethyl ester pressure column (T7).

5. The separation system for coal-to-ethanol thermal coupling separation by pressure difference according to claim 4, wherein the molecular sieve dehydration unit comprises a molecular sieve adsorber (A1), and a side line of the ethanol column (T3) is connected with the molecular sieve adsorber (A1).

6. The separation system for thermally coupling and separating coal-based ethanol by using pressure difference as claimed in claim 5, further comprising a recovery tower (T4) for recovering ethanol, wherein the bottom of the ethanol tower (T3) is connected with the recovery tower (T4).

7. The separation system for separating coal-based ethanol by pressure difference thermal coupling according to claim 5 or 6, further comprising a light ethanol tower (T10) for recovering light ethanol, wherein the molecular sieve adsorber (A1) is connected with the light ethanol tower (T10).

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