A deodorization process for a methanol solution containing malodorous substances

Abstract

The application discloses a deodorization process of a methanol solution containing malodorous substances, and comprises the following steps: S1, after adding an extractant and heating, adding a methanol solution containing malodorous substances to carry out mixed rectification; S2, after the methanol solution containing malodorous substances changes into a gas phase and rises, continuously adding the extractant again; S3, after the methanol gas contacts with the extractant, changing into a liquid phase and refluxing, and controlling the refluxing temperature and flow rate; and collecting the malodorous substances after rising and condensing; wherein the mixing ratio of the extractant and the methanol solution containing malodorous substances in S1 is 0.9-1.1:0.9-1.1. The application can remove the light components such as dimethyl sulfide, methyl mercaptan, dimethyl disulfide, acetone and acetaldehyde in the methanol at a removal rate of 100% without adding other medicaments or substances and without affecting the regeneration and use of the methanol solution.

Description

Technical Field

[0001] This invention relates to the field of methanol solutions containing malodorous substances, and more specifically to a methanol solution deodorization process in the production of water-soluble fibers. Background Technology

[0002] Methanol is widely used as an excellent solvent. However, when used in the production of low-temperature water-soluble fibers, it can produce malodorous substances such as thiols, sulfides, and dimethyl disulfide due to the decomposition of dimethyl sulfoxide.

[0003] In actual production, methanol solutions containing malodorous substances such as thiols, sulfides, and dimethyl disulfide have a detrimental impact on the environment, and the odor must be removed before reuse.

[0004] Chinese patent document CN112707491A discloses a method for treating thioethers and thiols, comprising: adding an oxidant solution to a substance containing thioethers and / or thiols to carry out a reaction, wherein the oxidant is persulfate or a combination of persulfate and hydrogen peroxide and / or potassium permanganate. The method of this invention has a high removal rate of thioethers and thiols.

[0005] The existing technology has the following drawbacks: the method affects the physicochemical properties of the methanol solution, leading to abnormal production processes or even making it unusable. Summary of the Invention

[0006] The purpose of this invention is to provide a deodorization process for methanol solution that does not affect the regeneration and reuse of methanol solution.

[0007] On one hand, the present invention provides a deodorization process for a methanol solution containing malodorous substances, comprising the following steps:

[0008] S1: After adding the extractant and heating, add a methanol solution containing malodorous substances for mixed distillation;

[0009] S2: After the methanol solution containing malodorous substances changes from phase to gas and rises, the extractant is continuously added again to extract with the gas phase, and the extraction temperature and flow rate are controlled.

[0010] S3: After methanol comes into contact with the extractant, it becomes a liquid phase reflux; the odorous substances rise, condense, and are then collected.

[0011] In S1, the ratio of the extractant to the methanol solution containing malodorous substances is 0.9-1.1:0.9-1.1.

[0012] Furthermore, the extractant is desalinated water; this does not affect the physicochemical properties of the methanol solution and provides good treatment of odorous substances.

[0013] Furthermore, the odorous substances are a variety of substances selected from thiols, thioethers, dimethyl disulfide, azo dyes, acetone, acetaldehyde, butenal, and methyl acetate; this does not affect the physicochemical properties of the methanol solution and provides good treatment effect for substances containing odorous substances.

[0014] Furthermore, the distillation time is 3-4 hours.

[0015] Furthermore, the bottom temperature, reflux temperature, and tray temperature after adding the extractant in the entire process are 82-86℃, 50-55℃, and 50-55℃, respectively; this does not affect the physicochemical properties of the methanol solution and has a good treatment effect on odorous substances.

[0016] Furthermore, 1.8-2.2 parts of extractant are added again continuously; this does not affect the physicochemical properties of the methanol solution and has a good treatment effect on substances containing malodorous substances.

[0017] Furthermore, the rate at which the extractant is added again is 10-12 ml / min; this does not affect the physicochemical properties of the methanol solution and provides good treatment of odorous substances.

[0018] Furthermore, the extraction flow rate after the methanol comes into contact with the extractant is 10-12 ml / min; this does not affect the physicochemical properties of the methanol solution and has a good treatment effect on substances containing malodorous substances.

[0019] Furthermore, the entire process is heated by electric heating or steam heating; this does not affect the physicochemical properties of the methanol solution and has a good treatment effect on substances containing odor.

[0020] Furthermore, it includes the following steps:

[0021] S1: After adding the extractant and heating to 82-86℃, add a methanol solution containing malodorous substances in a mass ratio of 0.9-1.1:0.9-1.1 and carry out mixed distillation;

[0022] S2: After the methanol solution containing malodorous substances changes to a gas phase and rises, the extractant is continuously added again to extract the gas phase.

[0023] S3: After methanol comes into contact with the extractant, it becomes a liquid phase and is refluxed. The temperature is controlled at 50-55℃ and the flow rate is 10-12 ml / min. The odorous substances are collected after rising and condensing.

[0024] This method does not affect the physicochemical properties of the methanol solution and has a good effect on treating substances containing malodorous substances.

[0025] The present invention has the following beneficial effects:

[0026] 1) This invention uses desalinated water as the extractant, without adding other agents or substances, and does not affect the regeneration and use of methanol solution. The process is short, with low material and energy consumption, and the operation is completely closed, so it does not cause secondary pollution to the environment.

[0027] 2) The present invention achieves a 100% removal rate for light components such as dimethyl sulfide, methanethiol, dimethyl disulfide, acetone, and acetaldehyde in methanol; the removal rate of methyl acetate is greater than 99.6%; and only 100 ppm of butenal remains, with very little odor permeable to the odor emanating from the bottom of the tower.

[0028] 3) This invention is an economical, environmentally friendly, pollution-free, low-energy and low-material consumption methanol solution deodorization process and device. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an embodiment of methanol solution deodorization according to the present invention.

[0030] 1. Distillation column, 2. Condenser, 3. Separator, 4. Extractant feed pump, 5. Raw material feed pump, a. Raw material feed pipeline, b. Top material pipeline, c. Top reflux material pipeline, d. Top discharge material pipeline, f. Extractant feed pipeline, e. Bottom product material pipeline. Detailed Implementation

[0031] The examples provided are for illustrative purposes only and are not intended to limit the scope of the invention. Therefore, non-essential modifications and adjustments made to the embodiments by those skilled in the art based on the above description are still within the protection scope of this invention.

[0032] 1. Definition

[0033] Distillation is a separation process that uses the different volatility of components in a mixture to separate the components. Commonly used equipment includes plate distillation columns and packed distillation columns.

[0034] Continuous: This means that the addition is not done all at once, but rather a certain amount is added over a certain period of time.

[0035] 2. The present invention also includes the following preferred embodiments.

[0036] Preferably, the ratio of the extractant to the methanol solution containing the malodorous substance in S1 is 1:1.

[0037] Preferably, the temperatures after adding the extractant, the reflux temperature, and the tray temperature in the entire process are 84°C, 50°C, and 50°C, respectively.

[0038] This invention relates to equipment used in the methanol solution deodorization process during the production of water-soluble fibers.

[0039] The system includes a distillation column 1, a condenser 2, a separator 3, an extractant feed pump 4, and a feed pump 5. The top of the distillation column 1 is connected to one end of the condenser 2 via a top material pipe b, and the other end of the condenser 2 is connected to one end of the separator 3. The other end of the separator 3 is connected to two pipes: one is connected to the reflux port near the top of the distillation column 1 via a top reflux material pipe c, and the other is a top discharge material pipe d. The extractant feed pump 4 is connected to the top reflux material pipe c via an extractant feed pipe f, and is connected to the reflux port near the top of the distillation column 1. The feed pump 5 is connected to the feed inlet near the bottom of the column via a feed material pipe a. The bottom of the distillation column is connected to the bottom product material pipe e.

[0040] Example 1

[0041] like Figure 1 As shown, 1L of demineralized water is first pumped into the distillation column reboiler 1 through feed pipe a using feed pump 5, raising the reboiler temperature to 84℃. Then, 1L of methanol solution (containing malodorous substances such as thiols and sulfides) is continuously and slowly pumped into the reboiler through feed pipe a using feed pump 5. When the column top temperature reaches 50℃ and reflux occurs, 2L of demineralized water is continuously and slowly pumped into the column top reflux material pipe c using extraction feed pump 4 through extractant feed pipe f. The unit operates for 3 hours. The methanol solution rich in malodorous substances in the reboiler liquid rises as a gas phase and comes into contact with the demineralized water metered from the reflux port in the reflux section, causing the methanol to become a liquid phase and reflux. The malodorous substances continue to rise and are condensed by condenser 2. The malodorous substances and a small amount of methanol liquid phase are collected through the column top discharge material pipe d at the other end of the separator 3 for further disposal. The reboiler product, after sampling and analysis, is collected through the reboiler product material pipe e after passing the analysis.

[0042] Main process control

[0043] 84℃ 50℃ 50℃ 11ml / min

[0044] Raw material and process results analysis

[0045] Data table of extractive distillation experiments containing odorous methanol (components not analyzed, solvent water content not analyzed).

[0046]

[0047] As shown in the table, extractive distillation with demineralized water can remove light components such as dimethyl sulfide, methanethiol, dimethyl disulfide, acetone, and acetaldehyde from the methanol in the bottom of the distillation column. The removal rate of these components reaches 100%, leaving only 80 ppm of methyl acetate (removal rate greater than 99.6%) and 100 ppm of butenal. The odor in the bottom of the column is very weak. The light components in the 3S circulating methanol are discharged from the top of the column. Therefore, extractive distillation with demineralized water can achieve the purpose of removing light components such as thiols, sulfides, and dimethyl disulfide from methanol containing odor.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A deodorization process for a methanol solution containing malodorous substances, wherein the methanol solution containing malodorous substances originates from the production process of water-soluble fibers, characterized in that: Includes the following steps: S1: After adding the extractant and heating, add a methanol solution containing malodorous substances and perform mixed distillation; S2: After the methanol solution containing malodorous substances changes to a gas phase and rises, the extractant is added continuously again; S3: When methanol gas comes into contact with the extractant, it becomes liquid phase reflux. The reflux temperature and flow rate are controlled. Odorous substances rise, condense, and are then extracted. In S1, the ratio of the extractant to the methanol solution containing malodorous substances is (0.9-1.1):(0.9-1.1). The malodorous substances are a variety of substances including thiols, thioethers, dimethyl disulfide, azo dyes, acetone, acetaldehyde, butenaldehyde, and methyl acetate.

2. The deodorization process for a methanol solution containing malodorous substances according to claim 1, characterized in that: The extractant is desalinated water.

3. The deodorization process for a methanol solution containing malodorous substances according to claim 2, characterized in that: The distillation time is 3-4 hours.

4. A deodorization process for a methanol solution containing malodorous substances according to any one of claims 1-3, characterized in that: The temperatures of the bottom of the tower after adding the extractant, the reflux temperature, and the tray temperature in the entire process are 82-86℃, 50-55℃, and 50-55℃, respectively.

5. The deodorization process for a methanol solution containing malodorous substances according to claim 4, characterized in that: In step S2, 1.8-2.2 parts of extractant are added again.

6. A deodorization process for a methanol solution containing malodorous substances according to any one of claims 2, 3, and 5, characterized in that: In step S2, the rate at which the extractant is added again is 10-12 ml / min.

7. The deodorization process for a methanol solution containing malodorous substances according to claim 6, characterized in that: In step S3, the extraction flow rate after the methanol gas comes into contact with the extractant is 10-12 ml / min.

8. A deodorization process for a methanol solution containing malodorous substances according to any one of claims 2, 3, 5, and 7, characterized in that: The entire process is heated by either electric heating or steam heating.

9. The deodorization process for a methanol solution containing malodorous substances according to claim 8, characterized in that: Includes the following steps: S1: After adding the extractant and heating to 82-86℃, add a methanol solution containing malodorous substances at a mass ratio of (0.9-1.1):(0.9-1.1) for mixed distillation; S2: After the methanol solution containing malodorous substances changes to a gas phase and rises, the extractant is added continuously again; S3: After methanol gas comes into contact with the extractant, it becomes liquid phase reflux. The temperature is controlled at 50-55℃ and the flow rate is 10-12 ml / min, and the mixture is collected. The odorous substances rise, condense, and are then collected.

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