Dry waste sulfuric acid concentration device of chloromethane synthesis device

Abstract

The utility model provides a dried waste sulfuric acid concentration device of a chloromethane synthesis device. A waste sulfuric acid pipeline is connected with a sulfuric acid heat exchanger, a bottom outlet of the sulfuric acid heat exchanger is connected with a rectifying tower I, and a tower top outlet of the rectifying tower I is connected with a heat exchanger II; the heat exchanger II is connected through a return tank, the return tank and a process water pipeline are connected with an upper tower of a hydrolysis tower II, and the lower part of the upper tower of the hydrolysis tower II is connected with a heater through a pipeline and then connected with a lower tower of the hydrolysis tower II; the bottoms of the rectifying tower I and the hydrolysis tower II are connected with a sulfuric acid heat exchanger through pipelines, and concentrated sulfuric acid is recovered. The reflux tank is connected with the upper part of the rectifying tower I through a pipeline to realize partial circulation; the lower part of the upper tower of the hydrolysis tower II is connected with the heater through a pipeline and then is connected with the upper tower of the hydrolysis tower II. After part of organic matters and water are removed through an upper tower heater, the sulfuric acid in the tower kettle enters a lower tower of the hydrolysis tower and is concentrated through vacuum rectification;

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry and relates to a device for drying waste sulfuric acid and concentrating a chloromethane synthesis device. Background Art

[0002] In the production process of silicone monomers, methyl chloride is the main raw material. During its production process, it needs to be washed with concentrated sulfuric acid to remove water, dimethyl ether and other organic impurities. Dilute sulfuric acid will be produced in this process.

[0003] The dilute sulfuric acid produced as a by-product of the chloromethane synthesis process usually contains a certain amount of impurities such as chloromethane, dimethyl ether, and dimethyl sulfate.

[0004] The output of dilute sulfuric acid accounts for about 4.5% of the monomer production. As the scale of organosilicon monomer production expands, the output of dilute sulfuric acid will also increase.

[0005] The traditional sulfuric acid concentration and recovery process directly hydrolyzes the waste acid by adding water, which introduces a large amount of additional water, increases the processing capacity of the subsequent concentration device, and the dissolved methyl chloride cannot be effectively recovered and utilized. Summary of the Invention

[0006] The utility model provides a device for concentrating waste sulfuric acid dried from a chloromethane synthesis device, aiming to effectively recover the chloromethane dissolved therein and reduce the energy consumption for sulfuric acid concentration.

[0007] The purpose of the utility model is achieved through the following scheme:

[0008] The chloromethane synthesis unit is used to dry the waste sulfuric acid and concentrate the waste sulfuric acid pipeline, which is connected to the sulfuric acid heat exchanger. The bottom outlet of the sulfuric acid heat exchanger is connected to the first distillation tower, and the top outlet of the first distillation tower is connected to the second heat exchanger.

[0009] The second heat exchanger is connected via a reflux tank, the reflux tank and the process water pipeline are connected to the upper tower of the second hydrolysis tower, the lower part of the upper tower of the second hydrolysis tower is connected to the heater via a pipeline and then connected to the lower tower of the second hydrolysis tower;

[0010] The bottom of the first distillation tower and the bottom of the second hydrolysis tower are connected to the sulfuric acid heat exchanger through pipelines to recover concentrated sulfuric acid.

[0011] The reflux tank is connected to the upper part of the first distillation tower through a pipeline to achieve partial circulation; the lower part of the second upper tower of the hydrolysis tower is connected to the heater through a pipeline and is also connected to the second upper tower of the hydrolysis tower.

[0012] The reflux tank is provided with a vacuum pump 1, which is connected to the incineration tail gas;

[0013] The lower tower top of the hydrolysis tower two is connected with the heat exchanger three, the heat exchanger three is connected with the condenser, the condenser is connected with the vacuum pump two, and the vacuum pump two is connected with the methanol recovery tank; the upper tower top of the hydrolysis tower two is connected with the methanol recovery tank.

[0014] The sulfuric acid heat exchanger is connected with the filter, the filter is connected with the heat exchanger one, and the heat exchanger one is connected to the concentrated sulfuric acid storage tank.

[0015] A drying waste sulfuric acid concentration process of a chloromethane synthesis device, comprising the following process route:

[0016] (a) The waste sulfuric acid of chloromethane synthesis is heated and enters the rectification tower one after heat exchange with concentrated high-temperature concentrated sulfuric acid, and after rectification and heating concentration, 96% or more concentrated sulfuric acid is obtained, and the 96% or more concentrated sulfuric acid is filtered and cooled to obtain qualified concentrated sulfuric acid;

[0017] (b) After condensation, part of the gas phase at the top of the rectification tower one is mixed with water and enters the upper tower of the hydrolysis tower two for hydrolysis, and the other part is refluxed to the rectification tower one;

[0018] (b) Part of the material in the upper tower of the hydrolysis tower two enters the lower tower of the hydrolysis tower, and the material in the lower tower of the hydrolysis tower is heated and concentrated to obtain 96% or more concentrated sulfuric acid, and the 96% or more concentrated sulfuric acid is filtered and cooled to obtain qualified concentrated sulfuric acid.

[0019] In step (a), the composition of the waste sulfuric acid of chloromethane synthesis includes 8-10% of dimethyl sulfate, about 10-15% of water, 1-3% of chloromethane, and a small amount of dimethyl ether, methanol and other impurities

[0020] In step (a), the initial temperature of the waste sulfuric acid is 20-40℃, and the temperature of the waste sulfuric acid after heat exchange and temperature rise through the sulfuric acid heat exchanger 4 with the high-temperature concentrated sulfuric acid collected from the tower bottoms of the rectification tower one 1 and the lower tower of the hydrolysis tower 3 is 80-100℃, the waste sulfuric acid is heated to the required feed temperature of the rectification tower one 1 through coupled heat exchange, the steam consumption is reduced, and the stable operation of the rectification tower one 1 is facilitated.

[0021] In step (a), the temperature of the tower bottom of the rectification tower one is controlled at 120-150℃, the temperature of the tower top is controlled at 40-80℃, the reflux ratio is controlled at 2-3, and the tower top pressure is controlled at -0.085 to -0.1 MPa. By reducing the boiling point of the waste sulfuric acid through high vacuum degree, the relative volatility between components is increased, and the composition of the collected materials at the tower bottom and the tower top is ensured through the control of temperature and reflux ratio, so that the concentration of the concentrated sulfuric acid collected from the tower bottom reaches 95% or more, and the gas phase components condensed at the tower top are 1-2% of sulfuric acid, 5-6% of water, and 92-94% of dimethyl sulfate.

[0022] The mass ratio of the upper column feed of the hydrolysis column in step (b) to the condensed gas phase:water = 1:0.3-0.5. The circulation amount of the material of the upper column of the second hydrolysis column to the output amount ratio is 4-6. The bottom temperature of the upper column of the second hydrolysis column is controlled at 60-100℃, and the pressure of the upper column of the second hydrolysis column is controlled at 10-50kPa. The dimethyl sulfate is hydrolyzed into sulfuric acid and methanol by adding water, the heating, the circulation reflux of the column bottom, the column bottom temperature is controlled to ensure the complete hydrolysis, and the composition of the gas phase at the column top is 95-98% of methanol and 2-5% of water. The composition entering the lower column of the second hydrolysis column is 5-15% of water, 10-15% of methanol and 75-80% of sulfuric acid.

[0023] The bottom temperature of the lower column of the second hydrolysis column is controlled at 100-130℃, and the pressure of the lower column of the hydrolysis column is-0.08--0.1MPa. The high vacuum degree reduces the boiling point of sulfuric acid and increases the relative volatility between components, so that the concentration of the concentrated sulfuric acid collected from the column bottom reaches more than 95%, and the gas phase composition at the column top is 20-30% of water and 70-80% of methanol.

[0024] The methanol in the gas phase at the top of the upper column of the second hydrolysis column and the lower column of the hydrolysis column is recovered by a methanol recovery device.

[0025] Advantages of the utility model:

[0026] 1. The utility model utilizes the heat of the concentrated concentrated sulfuric acid to preheat the waste sulfuric acid, the waste sulfuric acid is heated to the required feed temperature of the rectifying column 1 by coupling heat exchange, the steam consumption is reduced, and the stable operation of the rectifying column 1 is favorable.

[0027] 2. The traditional sulfuric acid concentration process first carries out a hydrolysis process, a large amount of sulfuric acid exists in the waste sulfuric acid, the water addition amount is large, the subsequent concentrated water is increased, and the steam consumption is high. The utility model first carries out vacuum rectification, most of the sulfuric acid (98% of the sulfuric acid in the feed) in the waste sulfuric acid is concentrated in the column bottom by controlling the vacuum degree (-0.085--0.1MPa), the temperature (the column bottom temperature is controlled at 120-150℃, and the column top temperature is controlled at 40-80℃) and the reflux ratio (2-3), the dimethyl sulfate to be hydrolyzed is condensed at the column top, and then the hydrolysis and concentration are carried out according to the mass ratio and the process water (70% of the water directly introduced in the hydrolysis is reduced). BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The utility model discloses a device structure diagram, wherein, the rectifying column 1, the upper column of the hydrolysis column 2, the lower column of the hydrolysis column 3, the sulfuric acid heat exchanger 4, the heat exchanger 5-1, the heat exchanger 5-2, the heat exchanger 3 5-3, the reflux tank 6, the vacuum pump 1 7-1, the vacuum pump 2 7-2, the heater 8, the condenser 9, the reboiler 1 10-1, the reboiler 2 10-2, the filter 11. DETAILED DESCRIPTION

[0029] Example 1

[0030] The chloromethane synthesis device dry waste sulfuric acid concentration device, the waste sulfuric acid pipeline is connected with the sulfuric acid heat exchanger 4, the bottom outlet of the sulfuric acid heat exchanger 4 is connected with the rectifying column 1, and the overhead outlet of the rectifying column 1 is connected with the heat exchanger 2 5-2;

[0031] The heat exchanger 2 5-2 is connected through the reflux tank 6, the reflux tank 6 and the process water pipeline are connected with the upper tower of the hydrolysis column 2, the lower part of the upper tower of the hydrolysis column 2 is connected with the heater 8 through the pipeline, and then connected with the lower tower of the hydrolysis column 2;

[0032] The bottom of the rectifying column 1 and the bottom of the lower tower of the hydrolysis column 2 are connected with the sulfuric acid heat exchanger 4 through the pipeline, and concentrated sulfuric acid is recovered.

[0033] The reflux tank 6 is connected with the upper part of the rectifying column 1 through the pipeline, and part of the circulation is realized; the lower part of the upper tower of the hydrolysis column 2 is connected with the heater 8 through the pipeline, and then connected with the upper tower of the hydrolysis column 2.

[0034] The reflux tank 6 is provided with a vacuum pump 1 7-1, and the vacuum pump 1 7-1 is connected with the incineration tail gas;

[0035] The upper tower top of the hydrolysis column 2 is connected with the methanol recovery tank, and the lower tower top of the hydrolysis column 2 is connected with the heat exchanger 3 5-3, the heat exchanger 3 5-3 is connected with the condenser 9, the condenser 9 is connected with the vacuum pump 2 7-2, and the vacuum pump 2 7-2 is connected with the methanol recovery tank.

[0036] The sulfuric acid heat exchanger 4 is connected with the filter 11, the filter 11 is connected with the heat exchanger 1 5-1, and the heat exchanger 1 5-1 is connected to the concentrated sulfuric acid storage tank.

[0037] Example 2

[0038] Taking 100 tons of chloromethane synthesis waste sulfuric acid as an example, the device of example 1 is used to carry out the following process:

[0039] The waste sulfuric acid feed amount is controlled to be 0.7 t / h, the waste sulfuric acid first enters the sulfuric acid heat exchanger 4, exchanges heat with the concentrated concentrated sulfuric acid after concentration, the temperature is increased to 80 DEG C, then enters the rectifying column 1, the column bottom temperature of the rectifying column 1 is controlled to be 140-150 DEG C, the steam addition amount of the reboiler 10-1 is 0.5 t / h; the column top temperature is controlled to be 70-80 DEG C, the column top reflux amount is 0.6 m 3 / h, the overhead pressure was controlled by vacuum pump 7-1 at -0.085 to -0.1 MPa, the distillation column 1 column bottom output was 0.55 t / h, the materials in reflux tank 6 entered the upper hydrolysis column 2 at 0.13 t / h mixed with 0.05 t / h of process water, the upper hydrolysis column 2 bottom temperature was controlled at 60 to 100 DEG C, the heater 8 steam addition was 0.1 t / h, the upper hydrolysis column 2 pressure was controlled at 10 to 50 kPa; the lower hydrolysis column 3 bottom temperature was controlled at 100 to 130 DEG C, the reboiler 10-2 steam addition was 0.2 t / h, the lower hydrolysis column 3 pressure was controlled by vacuum pump 7-1 at -0.08 to -0.1 MPa, the lower hydrolysis column 3 column bottom output was 0.1 t / h.

Claims

1. A drying waste sulfuric acid concentration device of a chloromethane synthesis device, characterized by, The chloromethane synthesis device dry waste sulfuric acid concentration device, the waste sulfuric acid pipeline is connected with the sulfuric acid heat exchanger (4), the bottom outlet of the sulfuric acid heat exchanger (4) is connected with the rectifying tower one (1), the tower top outlet of the rectifying tower one (1) is connected with the heat exchanger two (5-2); The heat exchanger two (5-2) is connected through the reflux tank (6), the reflux tank (6) and the process water pipeline are connected with the upper tower of the hydrolysis tower two (2), the lower part of the upper tower of the hydrolysis tower two (2) is connected with the heater (8) through the pipeline and then connected with the lower tower of the hydrolysis tower two (2); The bottom of the rectifying tower one (1) and the bottom of the lower tower of the hydrolysis tower two (2) are connected with the sulfuric acid heat exchanger (4) through the pipeline, and concentrated sulfuric acid is recovered.

2. The chloromethane synthesis device dry waste sulfuric acid concentration device according to claim 1, wherein the reflux tank (6) is connected with the upper part of the rectifying tower one (1) through the pipeline to realize partial circulation; the lower part of the upper tower of the hydrolysis tower two (2) is connected with the heater (8) through the pipeline and then connected with the upper tower of the hydrolysis tower two (2).

3. The chloromethane synthesis device dry waste sulfuric acid concentration device according to claim 1, wherein a vacuum pump one (7-1) is arranged on the reflux tank (6) and connected with the incineration tail gas; the top part of the lower tower of the hydrolysis tower two (2) is connected with the heat exchanger three (5-3), the heat exchanger three (5-3) is connected with the condenser (9), the condenser (9) is connected with the vacuum pump two (7-2), the vacuum pump two (7-2) is connected with the methanol recovery tank; the top part of the upper tower of the hydrolysis tower two (2) is connected with the methanol recovery tank.

4. The chloromethane synthesis device dry waste sulfuric acid concentration device according to claim 1, wherein the sulfuric acid heat exchanger (4) is connected with the filter (11), the filter (11) is connected with the heat exchanger one (5-1), and the heat exchanger one (5-1) is connected to the concentrated sulfuric acid storage tank. ​ ​ ​

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