Recycling system for residual liquid of dimethyl sulfate rectifying still

Abstract

The utility model provides a dimethyl sulfate rectifying still raffinate recycling system which is characterized by comprising an evaporation kettle and a hydrolysis kettle, a raffinate outlet pipe arranged at the bottom of the evaporation kettle is communicated with the hydrolysis kettle, and a methanol outlet pipe arranged at the top of the hydrolysis kettle is communicated with a first cooler to output cooled methanol to a processing device. A sulfuric acid outlet pipe arranged at the bottom of the hydrolysis kettle is communicated with the decolorizer to remove colored impurities and then output to a processing device. The device has the beneficial effects that according to different boiling points in the composition of the dimethyl sulfate tower bottoms, dimethyl sulfate with higher economic value is recovered through reduced pressure distillation, and sulfuric acid with economic value is produced from heavy components through hydrolysis, so that the aim of efficiently recovering and reusing the dimethyl sulfate tower bottoms is fulfilled.

Description

Technical Field

[0001] The utility model relates to the technical field of residual liquid recovery, in particular to a system for recovering residual liquid from a dimethyl sulfate distillation kettle. Background Art

[0002] Dimethyl sulfate is an important chemical intermediate and methylating agent, and is used in most industries of the national economy, including the pharmaceutical industry, agriculture, textile industry, construction industry, petrochemical industry, paper industry, food industry, and daily chemical production.

[0003] Currently, dimethyl sulfate is mostly produced industrially by reacting dimethyl ether with sulfur trioxide. First, dimethyl ether is dehydrated with methanol to produce dimethyl ether. 25% fuming sulfuric acid is then heated to evaporate sulfur trioxide gas, which is then sprayed with dimethyl sulfate to absorb the sulfur trioxide gas until it reaches near saturation, forming the mother liquor. The sulfur trioxide-absorbed dimethyl sulfate mother liquor reacts with dimethyl ether gas in an esterification tower to produce crude dimethyl sulfate. The crude dimethyl sulfate is then subjected to vacuum distillation to produce refined dimethyl sulfate. The residual liquid in the bottom of the dimethyl sulfate tower after vacuum distillation contains sulfuric acid, methyl bisulfate, and dimethyl sulfate. This residual liquid has a complex composition, making recovery difficult. The sulfuric acid content is also known to cause severe corrosion to equipment.

[0004] Currently, the primary treatment method for distillation still residue is alkali neutralization. However, this process produces a large amount of waste salt solution, which also generates significant heat and carries with it some waste gases. This waste salt solution is challenging to handle. Furthermore, this waste gas contains not only inorganic acidic gases but also a certain amount of organic waste gases, resulting in a complex composition and difficulty in treatment. Utility Model Content

[0005] In order to solve the problem that the current distillation kettle residual liquid is difficult to treat, the utility model provides a recycling and utilization system for the dimethyl sulfate distillation kettle residual liquid, including an evaporator and a hydrolysis kettle. A residual liquid outlet pipe is provided at the bottom of the evaporator to connect to the hydrolysis kettle, a methanol outlet pipe is provided at the top of the hydrolysis kettle to connect to a first cooler to output the cooled methanol to a processing device, and a sulfuric acid outlet pipe is provided at the bottom of the hydrolysis kettle to connect to a decolorizer to remove colored impurities and then output to the processing device.

[0006] As a preferred solution, the evaporator is provided with a raw material inlet pipe to input the dimethyl sulfate tower bottom liquid raw material.

[0007] As a preferred solution, a gas phase outlet pipe is provided on the top of the evaporator to communicate with a second cooler to cool the discharged dimethyl sulfate gas.

[0008] Furthermore, the first cooler is provided with an outlet pipe connected to the first cache tank, the second cooler is provided with an outlet pipe connected to the second cache tank, and the first cache tank and the second cache tank are respectively provided with gas outlet pipes at the top to connect to the catalytic burner to burn and discharge exhaust gas.

[0009] Furthermore, the catalytic combustor is provided with a third cache tank to collect exhaust gas discharged from the first cache tank and the second cache tank.

[0010] As a preferred solution, a fourth buffer tank is provided between the hydrolysis kettle and the decolorizer to collect the sulfuric acid solution.

[0011] The beneficial effects of the utility model are:

[0012] The utility model recovers dimethyl sulfate with high economic value from the distillation kettle residue by reduced pressure distillation according to the different boiling points of dimethyl sulfate tower bottom liquid components, produces sulfuric acid with economic value by hydrolysis of heavy components, and achieves the purpose of efficiently recovering and reusing the bottom liquid of the dimethyl sulfate distillation kettle residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein

[0014] Figure 1 A schematic structural diagram of the present utility model.

[0015] The reference numerals in the accompanying drawings are:

[0016] 1. Evaporator; 11. Residual liquid outlet pipe; 12. Raw material inlet pipe; 13. Gas phase outlet pipe; 2. Hydrolysis kettle; 21. Methanol outlet pipe; 22. Sulfuric acid outlet pipe; 3. First cooler; 4. Decolorizer; 5. Second cooler; 6. First buffer tank; 7. Second buffer tank; 8. Catalytic burner; 9. Third buffer tank; 10. Fourth buffer tank. DETAILED DESCRIPTION

[0017] To illustrate the features of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Example:

[0019] See also Figure 1The embodiment of the utility model provides a system for recycling the residual liquid of a dimethyl sulfate distillation kettle, comprising an evaporator 1 and a hydrolysis kettle 2. The evaporator 1 is provided with a raw material inlet pipe 12 for inputting dimethyl sulfate tower bottom liquid raw material, and the top of the evaporator 1 is provided with a gas phase outlet pipe 13 connected to a second cooler 5 to cool the discharged dimethyl sulfate gas, thereby realizing the preliminary separation of the raw material. A residual liquid outlet pipe 11 is provided at the bottom of the evaporator 1 to connect to the hydrolysis kettle 2, and the residual liquid at the bottom of the kettle is collected and hydrolyzed. Specifically, a methanol outlet pipe 21 is provided at the top of the hydrolysis kettle 2 to connect to the first cooler 3 to output the cooled methanol to a processing device, and the easily vaporized part of the residual liquid at the bottom of the kettle is vaporized and cooled and collected. A sulfuric acid outlet pipe 22 is provided at the bottom of the hydrolysis kettle 2 to connect to a decolorizer 4 to remove colored impurities in the sulfuric acid solution and then output to the processing device, thereby realizing the recovery of sulfuric acid in the residual liquid at the bottom of the kettle.

[0020] In addition, this embodiment is equipped with multiple buffer devices based on multi-line recovery. Specifically, an outlet pipe is provided at the first cooler 3 to connect to the first buffer tank 6, and an outlet pipe is provided at the second cooler 5 to connect to the second buffer tank 7. The first buffer tank 6 and the second buffer tank 7 are respectively provided with gas outlet pipes at the top to connect to the catalytic burner 8 to burn and discharge exhaust gas, and a third buffer tank 9 is provided at the catalytic burner 8 to collect the exhaust gas discharged from the first buffer tank 6 and the second buffer tank 7. A fourth buffer tank 10 is also provided between the hydrolysis kettle 2 and the decolorizer 4 to collect the sulfuric acid solution.

[0021] In this embodiment, based on the different boiling points of the dimethyl sulfate bottom liquid components, dimethyl sulfate with higher economic value is recovered by vacuum distillation, and the heavy components are hydrolyzed to produce economically valuable sulfuric acid, thereby achieving the purpose of efficiently recovering and reusing the dimethyl sulfate bottom liquid.

[0022] The above embodiments and accompanying drawings are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the spirit of the present invention do not depart from the spirit of the present invention and are intended to fall within the scope of the claims of the present invention. Other related technical structures not fully disclosed in this utility model are prior art in the art.

Claims

1. A system for recycling dimethyl sulfate distillation still residue, characterized in that: The invention comprises an evaporation kettle (1) and a hydrolysis kettle (2). A residual liquid outlet pipe (11) is provided at the bottom of the evaporation kettle (1) and is connected to the hydrolysis kettle (2). A methanol outlet pipe (21) is provided at the top of the hydrolysis kettle (2) and is connected to a first cooler (3) to output the cooled methanol to a processing device. A sulfuric acid outlet pipe (22) is provided at the bottom of the hydrolysis kettle (2) and is connected to a decolorizer (4) to remove colored impurities and then output to the processing device.

2. The recycling system of dimethyl sulfate rectifying still residue according to claim 1, wherein: The evaporator (1) is provided with a raw material inlet pipe (12) for inputting dimethyl sulfate tower bottom liquid raw material.

3. The recycling system of dimethyl sulfate rectifying still residue according to claim 1, wherein: A gas phase outlet pipe (13) is provided on the top of the evaporator (1) and is connected to the second cooler (5) to cool the discharged dimethyl sulfate gas.

4. The recycling system of dimethyl sulfate rectifying still residue according to claim 3, wherein: The first cooler (3) is provided with an outlet pipe connected to the first buffer tank (6), the second cooler (5) is provided with an outlet pipe connected to the second buffer tank (7), and the first buffer tank (6) and the second buffer tank (7) are respectively provided with gas outlet pipes at the top to connect to the catalytic burner (8) for combustion and exhaust gas discharge.

5. The recycling system of dimethyl sulfate rectifying still residue according to claim 4, wherein: The catalytic burner (8) is provided with a third buffer tank (9) for collecting exhaust gas discharged from the first buffer tank (6) and the second buffer tank (7).

6. The recycling system of dimethyl sulfate rectification still residue according to claim 1, wherein: A fourth buffer tank (10) is provided between the hydrolysis kettle (2) and the decolorizer (4) to collect the sulfuric acid solution.

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