阅读说明：本技术 一种控制甲醇精馏酸脱除和ph值的工艺及装置 (Process and device for controlling methanol rectification acid removal and pH value ) 是由 孙津生 刘道岩 王家豪 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种控制甲醇精馏酸脱除和PH值的工艺及装置。预塔回流槽设有左右两个槽位,甲醇精馏预塔塔顶出料至第一冷凝器,第一冷凝器汽相产品与第二冷凝器连接,第一冷凝器液相产品与预塔回流槽左槽连接；第二冷凝器汽相产品进入尾气洗涤塔,第二冷凝器液相产品与预塔回流槽左槽连接；以水作为萃取剂,吸收原料液中的轻组分后作为不凝汽通过不凝汽配管采出,尾气洗涤塔液相产品与预塔回流槽右槽连接,少量碱液通入尾气洗涤塔中段连接,侧线采出产品与预塔回流槽左槽连接；预塔回流槽左槽中的产品作回流至甲醇精馏预塔,预塔回流槽右槽中的以甲醇油为主的产品流出系统。本发明准确控制该体系PH值,可有效提升甲醇精馏酸脱除的处理效果。(The invention discloses a process and a device for controlling methanol rectification acid removal and pH value. The pre-tower reflux groove is provided with a left groove and a right groove, the top of the methanol rectification pre-tower discharges to a first condenser, a vapor phase product of the first condenser is connected with a second condenser, and a liquid phase product of the first condenser is connected with the left groove of the pre-tower reflux groove; the vapor phase product of the second condenser enters a tail gas washing tower, and the liquid phase product of the second condenser is connected with the left groove of the pre-tower reflux groove; taking water as an extracting agent, absorbing light components in a raw material liquid, taking the light components as non-condensed steam, and extracting the light components through a non-condensed steam pipe, wherein a liquid-phase product of a tail gas washing tower is connected with a right tank of a pre-tower reflux tank, a small amount of alkali liquor is introduced into a middle section of the tail gas washing tower and is connected, and a side-line extracted product is connected with a left tank of the pre-tower reflux tank; and the product in the left tank of the pre-tower reflux tank flows back to the methanol rectification pre-tower, and the product mainly containing methanol oil in the right tank of the pre-tower reflux tank flows out of the system. The invention accurately controls the PH value of the system and can effectively improve the treatment effect of methanol rectification acid removal.)

1. A process for controlling methanol rectification acid removal and pH value is characterized by comprising the following steps:

1) the vapor phase at the top of the methanol rectifying pre-tower (T1) is sent to a first condenser (C1), the vapor phase condensed by the first condenser (C1) is sent to a second condenser (C2), and the liquid phase of the first condenser (C1) flows into a left tank (V1L) of a pre-tower reflux tank;

2) the vapor phase of the second condenser (C2) is used as a raw material liquid to enter a tail gas washing tower (T2), and the liquid phase of the second condenser (C2) flows into a left groove (V1L) of a pre-tower reflux groove;

3) taking water as an extracting agent, absorbing light components in a raw material liquid, and then extracting the light components as non-condensed steam, wherein a tower bottom material of a tail gas washing tower (T2) flows into a right groove (V1R) of a pre-tower reflux groove, a small amount of alkali liquor is introduced into a middle section of the tail gas washing tower, and a side-stream is extracted and output to a left groove (V1L) of the pre-tower reflux groove; the reflux liquid collected by the left groove (V1L) of the pre-tower reflux groove is refluxed to the top of the methanol rectification pre-tower (T1), and the product mainly comprising methanol oil in the right groove (V1R) of the pre-tower reflux groove flows out of the system.

2. The process for controlling the removal of methanol rectification acid and the pH value according to claim 1, wherein the tail gas washing tower (T2) adopts a two-stage structure:

the upper section of the tail gas washing tower (T2) adopts extraction water to wash the methanol in the tail gas, thereby increasing the yield of the methanol;

the lower section of the tail gas washing tower (T2) strengthens the hydrolysis reaction of the esters, so that the esters form a high-concentration acid solution.

3. The process for controlling the removal of acid and the pH value of methanol rectification according to claim 1, wherein a small amount of alkaline aqueous solution is adopted in the tail gas washing tower (T2) to react with the ester which is not condensed, the acid enrichment process and the ester neutralization reaction are carried out synchronously, and the enriched acid is discharged out of the system along with the methanol oil through the right groove (V1R) of the pre-tower reflux groove.

4. The plant of a process according to any one of claims 1 to 3, characterized by comprising a methanol rectification pre-column (T1), a first condenser (C1), a second condenser (C2), a pre-column reflux drum (V1), a tail gas wash column (T2) and a DCS control system;

the pre-tower reflux groove (V1) is provided with a left groove and a right groove which are respectively a left groove (V1L) and a right groove (V1R) of the pre-tower reflux groove;

the top discharge of the methanol rectification pre-tower (T1) is connected with a first condenser (C1) through a pipeline I (S1), a vapor phase outlet of the first condenser (C1) is connected with a second condenser (C2), and a liquid phase outlet of the first condenser (C1) is connected with a left groove (V1L) of a pre-tower reflux groove; a vapor phase outlet of the second condenser (C2) is used as a raw material liquid to enter a tail gas washing tower (T2), and a liquid phase outlet of the second condenser (C2) is connected with a left groove (V1L) of the pre-tower reflux groove;

non-condensed steam is extracted through a non-condensed pipe (S5), a liquid phase outlet of a tail gas washing tower (T2) is connected with a right tank (V1R) of a pre-tower reflux tank through a pipeline II (S2), a small amount of alkali liquor is connected with the middle section of the tail gas washing tower through an alkali liquor pipe, and a side-line extracted product is connected with a left tank (V1L) of the pre-tower reflux tank through a pipeline VI (S6); the reflux liquid in the left tank (V1L) of the pre-tower reflux groove is connected with a methanol rectification pre-tower (T1) through a pipeline III (S3), and the product flows out from the bottom of the right tank (V1R) of the pre-tower reflux groove;

be equipped with Flowmeter (FL) on pipeline I (S1), be equipped with level gauge I (LG1) and level gauge II (LG2) on pipeline III (S3) and pipeline IV (S4), Flowmeter (FL), level gauge I (LG1) and level gauge II (LG2) be connected with DCS control system.

5. The apparatus according to claim 4, wherein the noncondensable pipe (S5) is provided with a backflow prevention structure.

6. The device of claim 4, wherein the device is constructed of SUS304 upgrade.

7. The apparatus according to claim 4, wherein the two troughs, left and right, of the pre-tower reflux drum (V1) are separated by a partition.

Technical Field

The invention belongs to the technical field of methanol rectification, and particularly relates to a process and a device for controlling acid removal and pH value of methanol rectification.

Background

Methanol is a chemical basic raw material with wide application, is applied to various fields such as fine chemical engineering, high molecules, pesticides, medicines, energy and the like, and has an important position in the international chemical industry market.

The pre-rectification process of the existing crude methanol is mainly finished in a pre-tower, and the pre-rectification aims to remove low-boiling components such as dimethyl ether and methyl formate contained in the crude methanol and non-condensed light components dissolved in the crude methanol, which have great influence on the quality of the subsequent rectification product of the methanol.

At present, extraction water of a rectification system is fed with crude methanol and is added into a pre-tower from the middle upper section of the pre-tower, impurity azeotrope accumulated in the top of the pre-tower and reflux cannot be effectively separated in the adding mode, and the reflux reaches a tower kettle, so that more crude alcohol impurities enter a subsequent refining process, and the product quality is seriously influenced.

The esterification reaction is more dominant than the hydrolysis reaction in the pre-tower, when the extraction water is added, the acid is generated by the change of the equilibrium, the acid is enriched at the top of the pre-tower and at the bottom of the tail gas washing tower, and the influence of the acidity on the product quality is very critical.

Disclosure of Invention

In order to solve the problems of the prior art, the invention provides a process and a device for controlling methanol rectification acid removal and pH value.

The technical scheme of the invention is a process for controlling methanol rectification acid removal and pH value, which comprises the following steps:

1) the vapor phase at the top of the methanol rectifying pre-tower T1 flows to a first condenser C1, the vapor phase condensed by the first condenser C1 flows to a second condenser C2, and the liquid phase of the first condenser C1 flows into a left groove V1L of a pre-tower reflux groove;

2) the vapor phase of the second condenser C2 is taken as raw material liquid to enter a tail gas washing tower T2, and the liquid phase of the second condenser C2 flows into a left groove V1L of the pre-tower reflux groove;

3) taking water as an extracting agent, absorbing light components in a raw material liquid, and then extracting the light components as non-condensed steam, wherein a bottom material of a tail gas washing tower T2 flows into a right groove V1R of a pre-tower reflux groove, a small amount of alkali liquor is introduced into the middle section of the tail gas washing tower, and the side-stream extracted water is output to a left groove V1L of the pre-tower reflux groove; the reflux liquid collected by the left groove V1L of the pre-tower reflux groove is refluxed to the top of a T1 pre-tower of the methanol rectification, and the product mainly comprising methanol oil in the right groove V1R) of the pre-tower reflux groove flows out of the system.

Further, the tail gas scrubbing tower T2 adopts a two-stage structure:

the methanol in the tail gas is washed by the extraction water at the upper section of the tail gas washing tower T2, so that the yield of the methanol is increased;

the lower section of the tail gas washing tower T2 strengthens the hydrolysis reaction of the esters, so that the esters form a high-concentration acid solution.

Further, a small amount of alkaline aqueous solution is adopted in the tail gas washing tower T2 to firstly react with the ester which is not condensed, the acid enrichment process and the ester neutralization reaction are synchronously carried out, and the enriched acid is discharged out of the system along with the methanol oil through the right groove V1R of the pre-tower reflux groove.

The second technical scheme of the invention is a device for removing the methanol rectification acid and controlling the pH value based on the process, which comprises a methanol rectification pre-tower T1, a first condenser C1, a second condenser C2, a pre-tower reflux tank V1, a tail gas washing tower T2 and a DCS control system.

The pre-tower reflux groove V1 is provided with a left groove and a right groove, and is a pre-tower reflux groove left groove V1L and a pre-tower reflux groove right groove V1R.

The top discharge of the methanol rectification pre-tower T1 is connected with a first condenser C1 through a pipeline S1, a vapor phase product of the first condenser C1 is connected with a second condenser C2, and a liquid phase product of the first condenser C1 is connected with a left groove V1L of a pre-tower reflux groove; a vapor-phase product of the second condenser C2 is used as a raw material liquid to enter a tail gas washing tower T2, and a liquid-phase product of the second condenser C2 is connected with a left groove V1L of a pre-tower reflux groove; taking water as an extracting agent, absorbing light components in a raw material liquid, taking the light components as non-condensed steam, and then extracting the light components through a non-condensed steam pipe S5, wherein a tail gas washing tower T2 liquid product is connected with a right tank V1R of a pre-tower reflux tank through a pipeline S2, a small amount of alkali liquor is connected with the middle section of the tail gas washing tower through an alkali liquor pipe, and a side-line extracted product is connected with a left tank V1L of the pre-tower reflux tank through a pipeline VI; the product in the left tank V1L of the pre-tower reflux tank is used as reflux liquid and is connected with a methanol rectification pre-tower T1 through a pipeline S3, and the product which mainly comprises methanol oil in the right tank V1R of the pre-tower reflux tank flows out of the system through a pipeline S4.

The pipeline S1 is provided with a flow meter FL, the pipeline S3 and the pipeline S4 are provided with a liquid level meter LG1 and a liquid level meter LG2, and the flow meter FL, the liquid level meter LG1 and the liquid level meter LG2 are connected with a DCS control system.

The scheme has the following characteristics:

1. the tail gas washing tower adopts a two-section structure, and the upper section of the tail gas washing tower adopts extraction water to wash methanol in the tail gas, so that the methanol yield is increased; the lower segment strengthens the hydrolysis reaction of the esters, so that the esters form a high-concentration acid solution;

2. the pre-tower reflux groove V1 is provided with a left groove and a right groove which are separated by a clapboard;

3. introducing a small amount of alkaline aqueous solution into the lower section of the tail gas washing tower to strengthen the hydrolysis reaction of esters, wherein the acid enrichment process and the ester neutralization reaction are synchronously carried out, and the enriched acid is discharged out along with the methanol oil through a pipeline S2 and a right groove V1R of a pre-tower reflux groove;

4. the non-condensed pipe S5 is provided with a structure for preventing the backflow of condensed liquid; the reflux system of the pre-rectifying tower is upgraded by adopting SUS304 material.

Advantageous effects

1. The tail gas washing tower adopts a two-stage absorption method, and the methanol yield can be increased through physical absorption; and then the hydrolysis reaction of the esters is strengthened through a chemical reaction, so that the effect of acid enrichment can be better achieved.

2. The baffle is arranged in the pre-tower reflux groove, so that the acid enriched at the bottom of the tail gas absorption tower and the crude methanol to be refluxed can be effectively separated, and the treatment effect of removing the methanol rectification acid is improved.

3. The PH value of a methanol rectification pre-tower system can be effectively controlled to be 7-9 by controlling the addition of the alkaline water solution and monitoring the liquid level of the pre-tower reflux tank by the liquid level meter, and the quality of a methanol product is improved.

4. The addition of the anti-condensation liquid backflow structure enables the non-condensation treatment to be more effective, and the treatment effect of removing the methanol rectification acid is also greatly influenced.

5. After the method is put into use, the technical problem that the quality of the methanol product is seriously influenced because the acid enters the pressurizing tower from the bottom of the tower and is esterified at high temperature in the prior art is thoroughly solved, and the qualification rate of the methanol product is greatly improved.

Drawings

FIG. 1 is a schematic diagram of a methanol rectification acid removal and pH control device;

wherein: the device comprises a methanol rectification pre-tower-T1, a first condenser-C1, a second condenser-C2, a pre-tower reflux tank-V1, a tail gas washing tower-T2, a pre-tower reflux tank left tank-V1L, a pre-tower reflux tank right tank-V1R, a pipeline I-S1, a pipeline II-S2, a pipeline III-S3, a pipeline IV-S4, an uncondensed pipe-S5, a pipeline VI-S6, a flow meter-FL, a liquid level meter I-LG 1 and a liquid level meter II-LG 2.

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

example 1

As shown in FIG. 1, the pre-column reflux drum V1 has two slots, i.e., a left pre-column reflux drum V1L and a right pre-column reflux drum V1R.

The process flow comprises the following steps: the top discharge of the methanol rectification pre-tower T1 is connected with a first condenser C1 through a pipeline S1, a vapor phase product of the first condenser C1 is connected with a second condenser C2, and a liquid phase product of the first condenser C1 is connected with a left groove V1L of a pre-tower reflux groove; a vapor-phase product of the second condenser C2 is used as a raw material liquid to enter a tail gas washing tower T2, and a liquid-phase product of the second condenser C2 is connected with a left groove V1L of a pre-tower reflux groove; taking water as an extracting agent, absorbing light components in a raw material liquid, taking the light components as non-condensed steam, and then extracting the light components through a non-condensed steam pipe S5, wherein a tail gas washing tower T2 liquid product is connected with a right tank V1R of a pre-tower reflux tank through a pipeline S2, a small amount of alkali liquor is connected with the middle section of the tail gas washing tower through an alkali liquor pipe, and a side-line extracted product is connected with a left tank V1L of the pre-tower reflux tank through a pipeline VI; the product in the left tank V1L of the pre-tower reflux tank is used as reflux liquid and is connected with a methanol rectification pre-tower T1 through a pipeline S3, and the product which mainly comprises methanol oil in the right tank V1R of the pre-tower reflux tank flows out of the system through a pipeline S4.

The pipeline S1 is provided with a flow meter FL, the pipeline S3 and the pipeline S4 are provided with a liquid level meter LG1 and a liquid level meter LG2, and the flow meter FL, the liquid level meter LG1 and the liquid level meter LG2 are connected with a DCS control system.

The tail gas washing tower T2 adopts a two-section structure, and the upper section of the tail gas washing tower T2 adopts extraction water to wash methanol in the tail gas, so that the methanol yield can be increased; the lower section of the tail gas washing tower T2 strengthens the hydrolysis reaction of the esters, so that the esters form a high-concentration acid solution, and the acid enrichment effect can be better achieved.

A small amount of alkaline aqueous solution is adopted in the tail gas washing tower to firstly react with esters which are not condensed, then the acid enrichment process and the ester neutralization reaction are synchronously carried out, and the enriched acid passes through a pipeline S2 and a pre-tower reflux groove right groove V1R and is discharged along with methanol oil.

The non-condensed pipe S5 is provided with a structure for preventing the backflow of condensed liquid; the addition of the anti-condensation liquid backflow structure enables the non-condensation treatment to be more effective, and the treatment effect of removing the methanol rectification acid is also greatly influenced. The reflux system of the pre-rectifying tower is upgraded by adopting SUS304 material. The tail gas washing tower adopts a two-stage absorption method, and the methanol yield can be increased through physical absorption; and then the hydrolysis reaction of the esters is strengthened through a chemical reaction, so that the effect of acid enrichment can be better achieved. The baffle is arranged in the pre-tower reflux groove, so that the acid enriched at the bottom of the tail gas absorption tower and the crude methanol to be refluxed can be effectively separated, and the treatment effect of removing the methanol rectification acid is improved. The PH value of a methanol rectification pre-tower system can be effectively controlled by controlling the addition of the alkaline water solution and monitoring the liquid level of the pre-tower reflux tank by the liquid level meter, and the quality of a methanol product is improved.