阅读说明：本技术 一种含少量水的乙酯甲苯有机废液分离方法 (Method for separating ethyl ester toluene organic waste liquid containing small amount of water ) 是由 赖耀明 于 2020-08-11 设计创作，主要内容包括：本发明涉及一种含少量水的乙酯甲苯有机废液分离方法,属于有机溶剂废液分离技术领域。上述分离方法包括：首先,将含有少量水的甲苯乙酯有机废液泵入脱水塔中,加热,保证脱水塔内液体不断气化,水分和少量有机物蒸出,经过冷凝分相后,水相分离至系统外；然后,由于乙酯和甲苯沸点差别较大,通过精馏的方法首先分离出沸点较低的乙酯,然后再对甲苯进行提纯即可。本发明首先采用共沸精馏的方式,利用甲苯作为夹带剂形成三元共沸体系,在塔顶将水直接分离出来,破除了甲苯-水和乙酯-水共沸的影响,实现三者的分离。(The invention relates to a method for separating ethyl ester toluene organic waste liquid containing a small amount of water, and belongs to the technical field of organic solvent waste liquid separation. The separation method comprises the following steps: firstly, pumping the organic waste liquor containing a small amount of water into a dehydration tower, heating to ensure that the liquid in the dehydration tower is continuously gasified, evaporating water and a small amount of organic matters, and separating a water phase to the outside of a system after condensation and phase separation; then, because the difference between the boiling points of the ethyl ester and the toluene is large, the ethyl ester with the lower boiling point is firstly separated by a rectification method, and then the toluene is purified. The invention firstly adopts an azeotropic rectification mode, and utilizes toluene as entrainer to form a ternary azeotropic system, and water is directly separated out at the tower top, thereby breaking the influence of toluene-water and ethyl ester-water azeotropy and realizing the separation of the toluene-water and the ethyl ester-water.)

1. A method for separating ethyl ester toluene organic waste liquid containing a small amount of water is characterized by comprising the following steps:

step 1: pumping the organic waste liquid containing a small amount of water into a dehydrating tower, continuously gasifying liquid in the dehydrating tower by heating, evaporating water and a small amount of organic matters, preheating the fed organic waste liquid by releasing latent heat of steam from a heat exchanger outside the dehydrating tower through a pipeline, condensing the organic waste liquid by a condenser, then falling into a condensate buffer tank for phase splitting, separating a water phase outside a system through a water splitting bag protruding from the bottom of the dehydrating tower, refluxing an organic phase on the upper layer to the dehydrating tower for gas-liquid exchange, and keeping stable operation conditions when the moisture content of the liquid at the bottom of the dehydrating tower is reduced to below 1000ppm by on-line detection through a moisture detector arranged in the dehydrating tower, and carrying out the next step; wherein the temperature of the liquid at the bottom of the dehydrating tower is 80-86 ℃; the temperature at the top of the tower is 70-75 ℃;

step 2: pumping the bottom liquid of the dehydration tower into a toluene-ethyl ester separation tower, continuously gasifying the bottom liquid by heating, gasifying ethyl ester with low boiling point, carrying a small amount of toluene vapor to the top of the toluene-ethyl ester separation tower, condensing by a condenser at the top of the toluene-ethyl ester separation tower, and completely refluxing into the tower until the gas-liquid balance in the tower is realized; adjusting the purity of the ethyl ester extracted from the top of the tower to the requirement according to the reflux ratio of 3-6, and then stably extracting an ethyl ester product; wherein the temperature of the liquid at the bottom of the toluene-ethyl ester separation tower is 110-115 ℃; the temperature of the tower top is 75-77 ℃;

and step 3: pumping the residual kettle liquid of the toluene-ethyl ester separation tower into a toluene purification tower, heating to continuously gasify liquid in the tower, gasifying the toluene to carry a small amount of impurities to the top of the toluene purification tower, condensing the impurities by a condenser at the top of the toluene purification tower, and then completely refluxing the gasified toluene-ethyl ester into the tower to realize gas-liquid balance in the tower; then regulating the purity of toluene extracted from the tower top to the required value according to the reflux ratio of 3-7, then stably extracting a toluene product, and discharging impurities out of the system; wherein the liquid temperature at the bottom of the toluene purification tower is 130-135 ℃; the temperature at the top of the tower is 110-112 ℃;

in the organic waste liquid in the step 1, the water content is 0.2-15 wt%, the toluene content is 45-55 wt%, the ethyl ester content is 35-47 wt%, and the other is heavy component impurities; the weight ratio of the evaporation capacity at the top of the dehydrating tower to the feeding capacity is 1.5-2.5.

2. The method for separating organic waste ethyl ester toluene containing a small amount of water according to claim 1, wherein the separation method is carried out in an ethyl ester toluene water separation system comprising a feed pump, a dehydration column, a toluene-ethyl ester separation column and a toluene purification column which are connected in series.

3. The method for separating the organic waste liquor of ethyl ester toluene containing a small amount of water according to claim 2, characterized in that a first heater is arranged at the bottom of the dehydration tower, and the organic waste liquor at the bottom of the dehydration tower is circulated in the first heater by a pump to obtain heat so as to be partially gasified and enter the dehydration tower; the top of the dehydration tower is sequentially communicated with a feeding preheater, a first condenser and a first condensate buffer tank, one side of the bottom of the first condensate buffer tank is provided with a water diversion bag protruding downwards, and the bottom of the water diversion bag is communicated with a water recovery pipeline device for recovering water; a first return pipeline is arranged on the other side of the bottom of the first condensate buffer tank, communicated with the top of the dehydration tower and used for returning the organic waste liquid; and a pipeline at the bottom of the dehydration tower is communicated with the toluene-ethyl ester separation tower.

4. The method for separating the ethyl ester-toluene organic waste liquid containing a small amount of water according to claim 3, wherein a second heater is arranged at the bottom of the toluene-ethyl ester separation tower, the mixed organic waste liquid at the bottom of the toluene-ethyl ester separation tower is circulated in the second heater by a pump to obtain heat so as to enable the heat to be partially gasified and enter the toluene-ethyl ester separation tower, a second condenser and a second condensate buffer tank are sequentially communicated at the top of the toluene-ethyl ester separation tower, a first three-way regulating pipeline is arranged at the bottom of the second condensate buffer tank, and a second return pipeline is arranged at one side of the second condensate buffer tank and is communicated with the top of the toluene-ethyl ester separation tower and is used for returning ethyl ester containing a; the other side is communicated with an ethyl ester recovery device through an ethyl ester recovery pipe.

5. The method for separating the ethyl ester toluene organic waste liquid containing a small amount of water as claimed in claim 4, wherein the bottom of the toluene-ethyl ester separation tower is communicated with a toluene purification tower, the organic waste liquid is pumped into the toluene purification tower from the bottom of the toluene-ethyl ester separation tower, a third heater is arranged at the bottom of the toluene purification tower, and the mixed organic waste liquid at the bottom of the toluene purification tower obtains heat through circulating flow in the third heater through a pump so as to enable the heat to be partially gasified and enter the toluene purification tower; the top of the third condensate buffer tank is communicated with a third condenser and a third condensate buffer tank in sequence, the bottom of the third condensate buffer tank is provided with a second three-way adjusting pipeline, wherein one side of the third condensate buffer tank is provided with a third return pipeline which is communicated with the top of the toluene purification tower and is used for refluxing the condensed toluene at the top of the tower so as to realize gas-liquid exchange with ascending steam in the tower; the other side is communicated with a toluene recovery device through a toluene recovery pipe.

6. The method for separating the organic waste liquor of ethyl ester with small water content in the claim 5, wherein a liquid level controller is arranged between the feeding pump and the dehydration tower and used for regulating and controlling the feeding of the organic waste liquor of ethyl ester with water content.

7. The method for separating the organic waste liquor of ethyl ester toluene containing a small amount of water according to claim 6, characterized in that the bottom of the water dividing bag is also connected with a moisture measurement controller; the bottom of the second condensate buffer tank is communicated with a first purity detection device; the bottom of the third condensate buffer tank is communicated with a second purity detection device; temperature monitors are arranged in the dehydration tower, the toluene-ethyl ester separation tower and the toluene purification tower.

8. The method for separating the organic waste liquor of ethyl ester toluene containing a small amount of water according to claim 7, characterized in that the bottom of the dehydration tower is communicated with a first lift pump, and the organic waste liquor is pumped into a toluene-ethyl ester separation tower; the bottom of the toluene-ethyl ester separation tower is communicated with a second lift pump, and organic waste liquid is pumped into a toluene purification tower; and the bottom of the toluene purification tower is communicated with a kettle liquid discharge pump to discharge impurities out of the system.

Technical Field

The invention relates to the technical field of separation of organic waste liquid containing water, and particularly provides a method for separating ethyl ester toluene organic waste liquid containing a small amount of water.

Background

With the rapid development of national economy, public concern about resource waste and environmental pollution is increasing. The unjustified use of resources is a major cause of environmental pollution. The pollution is eliminated, and the reasonable utilization of resources and the saving and emission reduction are started, wherein the resource and the renewable utilization of the chemical residual liquid are the main contents. The ideal comprehensive utilization of resources is to eat, dry and squeeze the resources as much as possible. However, under the restriction of domestic technical treatment conditions, in most cases, the main components in the resources are utilized, and the used or difficultly treated parts are discarded as wastes, thereby causing great waste and pollution. Therefore, the main form of resource comprehensive utilization is represented by separation, extraction, purification and regeneration of effective components of residual liquid resources.

Toluene and ethyl ester are important organic solvents widely used in chemical, pharmaceutical, dye and other fields. Toluene is an organic compound of aromatic hydrocarbon, and is in liquid state at room temperature, and has a boiling point of 110.8 deg.C and a density of 0.866g/cm³And is poorly soluble in water. Ethyl ester, i.e. ethyl acetate, is colorless transparent liquid, is easily volatile, has a boiling point of 77 ℃ and a density of 0.902g/cm³Slightly soluble in water.

In the industrial production process, most of organic waste liquid contains water, toluene and water form a binary azeotrope under normal pressure, ethyl ester and water can also form a binary azeotrope, and water can simultaneously form an azeotrope with toluene and ethyl ester, so that the separation is difficult.

Disclosure of Invention

In order to solve the problems that in the prior art, ethyl ester, toluene and water cannot be separated by common rectification, an extractant needs to be added in the traditional extractive rectification, the size and energy consumption of equipment are increased, and solvent pollution is easily caused; the invention provides a method for separating ethyl ester toluene organic waste liquid containing a small amount of water. The invention utilizes the azeotropic distillation principle, selects the most appropriate entrainer to form the lowest azeotrope, adopts toluene contained in the raw material as the entrainer to form a ternary azeotropic system, directly separates water at the tower top through the self-entrainment heterogeneous azeotropic distillation process, breaks the influence of toluene-water and ethyl ester-water binary azeotrope, and creates conditions for the subsequent separation of toluene-ethyl ester.

In order to solve the technical problems, the invention provides the following technical scheme:

in one aspect, the invention provides a method for separating ethyl ester toluene organic waste liquid containing a small amount of water, which comprises the following steps:

step 1: pumping the ethyl ester toluene organic waste liquid containing a small amount of water into a dehydration tower, continuously gasifying liquid in the dehydration tower by heating, evaporating water and a small amount of organic matters, preheating the fed organic waste liquid by releasing latent heat of steam from a heat exchanger outside the dehydration tower through a pipeline, condensing the preheated organic waste liquid by a condenser, falling into a condensate buffer tank for phase splitting, and separating a water phase from a system through a water splitting bag protruding from the bottom of the tank; the organic solvent floats on the upper layer of the water diversion package and flows back to the dehydration tower through the pipeline for gas-liquid exchange. The control of the water extraction amount in the water dividing bag is realized by adjusting the gasification rate of the organic waste liquid at the bottom of the tower (the larger the gasification rate is, the more water is separated). Through a moisture detector arranged in the dehydration tower, when the moisture content in the tower bottom liquid is detected to be reduced to below 1000ppm on line, the operation condition is kept stable, and the next step is carried out; wherein the temperature of the liquid at the bottom of the dehydrating tower is 80-86 ℃; the temperature at the top of the tower is 70-75 ℃;

step 2: pumping the liquid at the bottom of the dehydrating tower into a toluene-ethyl ester separation tower, continuously gasifying the liquid at the bottom of the dehydrating tower by heating, gasifying ethyl ester with low boiling point, carrying a small amount of toluene vapor to the top of the toluene-ethyl ester separation tower, condensing by a condenser outside the toluene-ethyl ester separation tower, and then completely returning to the tower until the gas-liquid balance in the tower is realized; in the operation process, the larger the reflux ratio is, the higher the product purity is, and the reflux ratio is adjusted to 3-6 until the ethyl ester meets the requirement of the extraction purity. According to the set reflux ratio, an ethyl ester product is stably extracted; wherein the temperature of the liquid at the bottom of the toluene-ethyl ester separation tower is 110-115 ℃; the temperature of the tower top is 75-77 ℃;

and step 3: pumping the residual liquid in the kettle of the toluene-ethyl ester separation tower into a toluene purification tower, heating to continuously gasify the liquid in the tower, gasifying the toluene to carry a small amount of impurity steam to the top of the toluene purification tower, condensing the steam by a condenser at the top of the toluene purification tower, and then returning the steam back to the tower until the gas-liquid balance in the toluene purification tower is realized; then regulating the purity of the toluene according to the reflux ratio of 3-7 until the purity meets the requirement, and stably extracting a toluene product according to the set reflux ratio; wherein the liquid temperature at the bottom of the toluene purification tower is 130-135 ℃; the temperature at the top of the tower is 110-112 ℃;

in the organic waste liquid in the step 1, the water content is 0.2-15 wt%, the toluene content is 45-55%, the ethyl ester content is 35-47%, and the other components are heavy component impurities; by evaporating the kettle liquid accumulated at the bottom of the tower, the condensate and the feed liquid falling from the top of the tower, the gasification rate of the organic waste liquid at the bottom of the tower (namely the weight ratio of the evaporation amount at the top of the dehydrating tower to the feed amount) is 1.5-2.5. The overhead evaporation is the sum of the overhead reflux and cut-off.

Furthermore, the separation process is carried out in an ethyl ester-toluene-water separation system, the system comprises a feed pump, a dehydration tower, a toluene-ethyl ester separation tower and a toluene purification tower which are sequentially communicated, and the organic waste liquid sequentially flows through the dehydration tower, the toluene-ethyl ester separation tower and the toluene purification tower through the feed pump.

Further, a first heater is arranged at the bottom of the dehydration tower, and organic waste liquid at the bottom of the tower flows in the first heater through a pump in a circulating manner to obtain heat so as to enable the heat to be partially gasified and enter the dehydration tower; the top of the dehydration tower is sequentially communicated with a feeding preheater, a first condenser and a first condensate buffer tank, one side of the bottom of the first condensate buffer tank is provided with a water distribution bag protruding downwards, the bottom of the water distribution bag is communicated with a water recovery pipeline device, the water recovery pipeline device is provided with an adjusting valve, and the opening degree of the water distribution bag is adjusted according to the water level height of the water distribution bag; the other side of the bottom of the first condensate buffer tank is provided with a first return pipeline communicated with the top of the dehydrating tower, the first return pipeline is provided with a flow regulating valve, opening degree regulation is carried out according to the liquid level height of the first condensate buffer tank body, the bottom pipeline of the dehydrating tower is communicated with the toluene-ethyl ester separating tower, and organic waste liquid is pumped into the toluene-ethyl ester separating tower from the bottom of the dehydrating tower.

Further, a second heater is arranged at the bottom of the toluene-ethyl ester separation tower, the mixed organic waste liquid at the bottom of the tower circularly flows in the second heater through a pump to obtain heat, so that the heat is partially gasified and enters the toluene-ethyl ester separation tower, the top of the mixed organic waste liquid is sequentially communicated with a second condenser and a second condensate buffer tank, a first three-way pipeline is arranged at the bottom of the second condensate buffer tank, a second return pipeline is arranged on one side of the mixed organic waste liquid, is communicated with the top of the toluene-ethyl ester separation tower and is used for returning ethyl ester containing a small amount of toluene, and a flow regulating valve is arranged on the second return pipeline; the other side is communicated with an ethyl ester recovery device through an ethyl ester recovery pipeline, and the ethyl ester recovery pipeline is provided with an ethyl ester recovery regulating valve. And the liquid level of the second condensate buffer tank controls the opening of the flow regulating valve and the ethyl ester recovery regulating valve on the second return pipeline, and the flow of the return pipeline is measured and fed back to an opening signal of the ethyl ester recovery regulating valve through cascade control, so that the corresponding reflux ratio is set.

Furthermore, the bottom of the toluene-ethyl ester separation tower is communicated with a toluene purification tower, mixed organic waste liquid at the bottom of the toluene purification tower is pumped into the toluene purification tower, a third heater is arranged at the bottom of the toluene purification tower, and the organic waste liquid at the bottom of the toluene purification tower flows in the third heater in a circulating mode through a pump to obtain heat, so that part of the heat is gasified and enters the toluene purification tower. The top communicates third condenser and third condensate buffer tank in proper order, the bottom of third condensate buffer tank sets up the second tee bend pipeline. One side of the third reflux pipeline is provided with a flow regulating valve, and the third reflux pipeline is communicated with the top of the toluene purification tower and is used for refluxing the toluene condensed in the third buffer tank so as to realize gas-liquid exchange with ascending steam in the toluene purification tower; the other side is communicated with a toluene recovery device through a toluene recovery pipeline, and the toluene recovery pipeline is provided with an adjusting valve. And the opening degree of the regulating valve and the opening degree of the toluene recovery regulating valve on the third return pipeline are controlled by the liquid level of the third condensate buffer tank, and the flow of the return pipeline is measured and fed back to the opening degree signal of the toluene recovery regulating valve through cascade control, so that the corresponding reflux ratio is set.

Preferably, a liquid level controller is further arranged between the feeding pump and the dehydration tower and used for regulating and controlling feeding of the organic waste liquid.

Further, the bottom of the water distributing drum is also connected with a moisture measurement controller; the bottom of the second condensate buffer tank is communicated with a first purity detection device; the bottom of the third condensate buffer tank is communicated with a second purity detection device; temperature monitors are arranged in the dehydration tower, the toluene-ethyl ester separation tower and the toluene purification tower.

Furthermore, the bottom of the dehydration tower is communicated with a first lift pump, the liquid level at the bottom of the dehydration tower is measured by a liquid level meter designed at the bottom of the dehydration tower, the opening degree of a regulating valve of an outlet pipeline of the first lift pump can be regulated according to liquid level feedback, organic waste liquid is pumped into the toluene-ethyl ester separation tower, and meanwhile, the liquid level at the bottom of the dehydration tower is ensured to be stable; the bottom of the toluene-ethyl ester separation tower is communicated with a second lift pump, the liquid level at the bottom of the toluene-ethyl ester separation tower is measured by a liquid level meter designed at the bottom of the toluene-ethyl ester separation tower, the opening degree of an adjusting valve of an outlet pipeline of the second lift pump can be adjusted according to liquid level feedback, organic waste liquid is pumped into the toluene purification tower, and meanwhile, the liquid level at the bottom of the toluene-ethyl ester separation tower is ensured to be stable; the bottom of the toluene purification tower is communicated with the kettle liquid discharge pump, the liquid level at the bottom of the toluene purification tower is measured by the liquid level meter arranged at the bottom of the toluene purification tower, the opening degree of the regulating valve on a pipeline of the kettle liquid discharge pump can be regulated according to liquid level feedback, the stability of the liquid level at the bottom of the toluene purification tower is ensured, and meanwhile, impurities are discharged out of the system.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, water in the raw material organic waste liquid is firstly separated out through azeotropic distillation and the affinity and hydrophobicity characteristics of different organic solvents and water, the azeotropy of toluene-water and ethyl ester-water is destroyed, and then high-purity ethyl ester and toluene are separated through the boiling point difference, so that the purpose of purifying and separating organic matters in the mixed liquid is achieved. The invention does not use extra extractants and other additives, and has the advantages of physical purification, low cost, high product purity and clear and simple equipment and process.

The invention uses three-tower rectification, firstly, the azeotropic composition-water in the ternary azeotrope is distilled off from the tower top of the first dehydration tower, then the ethyl ester is distilled off from the tower top of the second toluene-ethyl ester separation tower, and finally the toluene is distilled off from the tower top of the third toluene purification tower. The invention is suitable for continuous production and intermittent production, and has high operation flexibility. The equipment is compact, the occupied space is small, and the arrangement on a flat surface is convenient.

Drawings

FIG. 1 is a schematic diagram of a system for separating ethyl ester from toluene water according to example 1 of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is made with reference to the accompanying drawings and specific embodiments.

The invention provides a method for separating organic waste liquid containing a small amount of ethyl ester toluene, which realizes the separation of ethyl ester toluene water through a corresponding system, and the specific embodiment is as follows.