CN113354172A

CN113354172A - Sulfolane wastewater recycling treatment method

Info

Publication number: CN113354172A
Application number: CN202110636672.1A
Authority: CN
Inventors: 李战胜; 宋嘉钰; 蹇锡高; 丁秋霞
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2021-09-07

Abstract

The invention relates to a recycling treatment method of sulfolane wastewater, belonging to the field of wastewater treatment. The method comprises the following steps: extracting the wastewater and the extracting agent in an extraction tower or a mixed clarifier to obtain an extraction phase and an extraction raffinate phase, discharging or recycling the extraction raffinate phase, performing four-effect evaporation on the extraction phase, recovering the extracting agent at the top of a flash evaporation tower for recycling, and recovering the sulfolane at the bottom of the tower. The sulfolane wastewater recycling treatment method provided by the invention has the advantages of simple process, convenience in operation, energy conservation and high efficiency, and after the wastewater is treated by the method, the sulfolane content in the raffinate phase is less than 50 mg/l.

Description

Sulfolane wastewater recycling treatment method

Technical Field

The invention relates to a recycling treatment method of chemical wastewater containing sulfolane, belonging to the field of wastewater treatment.

Background

Sulfolane, also known as tetrahydrothiophene-1, 1-dioxide, is an excellent aprotic polar solvent, and is miscible with acetone, water, toluene, and the like. Sulfolane is an ideal aromatic extraction solvent. Sulfolane in sulfolane waste water that petrochemical process produced is higher, and direct discharge not only pollutes the environment, still can cause the waste of resource. Therefore, the method for efficiently and energy-saving recycling the sulfolane in the wastewater is an effective way for realizing the reclamation and harmlessness of the wastewater.

The industry mainly adopts the four-effect evaporation process to treat the sulfolane wastewater. Generally, the mass fraction of sulfolane in sulfolane wastewater is about 10%, about 90% of water vapor needs to be removed in the four-effect evaporation process, the latent heat of evaporation of water is large, and the energy consumption of the process is very high.

Therefore, a new method is developed to reduce the energy consumption of sulfolane wastewater treatment, realize the resource utilization of sulfolane and have greater application value.

Disclosure of Invention

Aiming at the defects of high energy consumption and poor economical efficiency of recycling sulfolane wastewater in the traditional four-effect evaporation process, the invention aims to provide a novel sulfolane wastewater recycling method, which can efficiently and energy-saving recycle sulfolane and realize wastewater recycling treatment.

In order to solve the technical problems, the invention adopts the technical scheme that:

a recycling treatment method of sulfolane wastewater comprises the following steps:

a. firstly, extracting chemical wastewater containing sulfolane with an extractant to obtain an extract phase and a raffinate phase, wherein the theoretical stage number of extraction equipment is 1-20;

b. carrying out multi-effect evaporation on the extraction phase, recovering the extractant and sulfolane, and carrying out multi-effect evaporation;

c. and (c) cooling the extractant recovered in the step b for recycling.

In the method for extracting and recovering sulfolane from chemical wastewater, the extracting agent is dichloromethane, trichloromethane, 1-dichloroethane, 1, 2-dichloroethane, toluene, nitrobenzene or cyclohexanone. The extraction temperature is 15-30 ℃, the pressure is 0.1MPa, the volume ratio of the extracting agent to the waste water is 1:10-3:1, preferably 1:3-3:1, and the extraction theoretical stage number is 1-20. If the extraction temperature is too high, the volatilization loss amount of the solvent is large, and if the extraction temperature is too low, the energy consumption of wastewater feeding and cooling is large; if the ratio is too large, the solvent consumption is increased and the energy consumption for solvent recovery is increased, and if the ratio is too small, the sulfolane extraction rate is low.

The extraction equipment used in the method for extracting and recovering sulfolane from sulfolane wastewater is an extraction tower or a mixer-settler. If the extraction tower is adopted, the wastewater and the extracting agent are respectively pumped into the extraction tower from the bottom and the top of the extraction tower to carry out countercurrent extraction, so as to obtain an extract phase and a raffinate phase; in the case of a mixer-settler, the wastewater is fed from the first stage and fresh extractant from each stage.

The extraction phase is subjected to a multi-effect evaporation process to recover the extractant and the sulfolane, and the used equipment is a multi-effect evaporation tower. Taking four-effect evaporation as an example, the operating pressure ratio of each effect is 2.5:1.9:1.4: 1.0.

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

1) the energy consumption of the whole separation and recovery process is greatly reduced. The traditional four-effect evaporation process is to separate sulfolane from water, the extraction process converts the sulfolane-water separation into the sulfolane-extractant separation by adding the extractant, the extraction is carried out at normal temperature and normal pressure, and the energy consumption is low.

2) Simple technological process and less equipment investment. The extractant can be recycled, the recovery rate of the sulfolane is high, the separation effect is good, the content of the sulfolane in the wastewater can be reduced to below 50mg/l, the sulfolane and water can be recycled, and the sulfolane wastewater can be recycled.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following examples, but the present invention is not limited thereto.

The invention adopts dichloromethane, trichloromethane, 1-dichloroethane, 1, 2-dichloroethane, toluene, nitrobenzene and cyclohexanone as extracting agents, firstly, the wastewater and the extracting agents are extracted in an extraction tower or a mixed clarifier to obtain an extraction phase and a raffinate phase, and then the extraction phase is used for recovering the extracting agents in a multi-effect evaporation mode. The recovered extractant is cooled for recycling. The extraction temperature is 15-30 ℃, and the volume ratio of the extracting agent to the waste water is 1:10-3:1, the extraction theoretical stage number is 1-20. Taking four-effect evaporation as an example, the operating pressure ratio of each effect is 2.5:1.9:1.4: 1.0.

Example 1

The method is adopted, 1, 2-dichloroethane is selected as an extracting agent, and the extraction equipment is a mixer clarifier. Adding the waste water from the first stage, adding the fresh extracting agent from each stage, carrying out cross-flow extraction to obtain an extract phase and a raffinate phase, and then recovering the extracting agent from the extract phase in a four-effect evaporation mode. The recovered extractant is cooled for recycling. The extraction temperature is 25 ℃, the pressure is 0.1MPa, and the volume ratio of the extracting agent to the waste water is 1:1, the extraction theoretical stage number is 7. The operating pressure ratio of each effect of the four-effect evaporation is 2.5:1.9:1.4: 1.0. The operating temperature of the bottom of the four-effect flash column was 140.0 ℃. The using amount of 0.3MPa saturated steam is 12900kg/h

The sulfolane content in the treated wastewater is less than 50 mg/L.

Example 2

The method is adopted, the extracting agent is dichloromethane, and the extracting equipment is an extracting tower. Pumping the waste water and the extracting agent into the extraction tower from the bottom and the top of the extraction tower respectively, carrying out countercurrent extraction to obtain an extract phase and a raffinate phase, and then recovering the extracting agent from the extract phase in a four-effect evaporation mode. The recovered extractant is cooled for recycling. The extraction temperature is 25 ℃, the pressure is 0.1MPa, and the volume ratio of the extracting agent to the waste water is 1: 2, the number of extraction theoretical stages is 17. The operating pressure ratio of each effect of the four-effect evaporation is 2.5:1.9:1.4: 1.0. The bottom operating temperature of the four-effect flash column was 161.0 ℃. The dosage of 0.3MPa saturated steam is 8057 kg/h.

The sulfolane content in the treated wastewater is less than 50 mg/L.

Comparative example 1

A set of treatment equipment with the treatment capacity of 100 tons of wastewater per hour has the sulfolane content of 100g/L, adopts a four-effect evaporation process, and has the operating pressure ratio of each effect of 2.5:1.9:1.4: 1.0. The operating temperature of the bottom of the four-effect flash column was 122.7 ℃. The saturated steam dosage is 40050 kg/h.

The mass content of sulfolane in the treated wastewater is 1.09%, which is far more than 50 mg/L.

Claims

1. A sulfolane waste water recycling treatment method is characterized by comprising the following steps:

b. carrying out multi-effect evaporation on the extraction phase, and recovering the extractant and sulfolane;

c. and (c) cooling the extractant recovered in the step b for recycling.

2. A sulfolane waste water resource treatment method according to claim 1, characterized in that the extractant is dichloromethane, chloroform, 1-dichloroethane, 1, 2-dichloroethane, toluene, nitrobenzene or cyclohexanone.

3. The method for recycling sulfolane waste water according to claim 1, wherein the extraction equipment is an extraction tower or a mixer-settler.

4. The recycling treatment method of sulfolane waste water according to claim 3, characterized in that when the extraction equipment is an extraction tower, the chemical waste water and the extracting agent are respectively pumped into the extraction tower from the bottom and the top of the extraction tower to carry out countercurrent extraction, so as to obtain an extract phase and a raffinate phase.

5. A method for recycling sulfolane waste water according to claim 3, wherein when the extraction apparatus is a mixer-settler, the chemical waste water is fed from the first stage and fresh extractant is fed from each stage.

6. The recycling treatment method of sulfolane waste water according to claim 1, characterized in that the extraction process conditions are as follows: the extraction temperature is 15-30 ℃, the pressure is 0.1MPa, and the volume ratio of the extracting agent to the chemical wastewater is 1:10-3: 1.

7. A recycling treatment method of sulfolane waste water according to claim 6, characterized in that the volume ratio of the extracting agent to the chemical waste water is 1:3-3: 1.

8. The recycling method of sulfolane waste water according to claim 1, wherein the multi-effect evaporation apparatus is a multi-effect flash tower.

9. The method for recycling sulfolane waste water according to any one of claims 1 to 8, wherein the waste water is treated by the method comprising the steps of,

the multi-effect evaporation is four-effect evaporation.

10. A sulfolane waste water resource treatment method according to claim 9, characterized in that said four-effect evaporation process conditions are as follows: the operating pressure ratio for each effect was 2.5:1.9:1.4: 1.0.