Acidic DMF (Dimethyl Formamide) recovery treatment system
By using ammonia neutralization reaction and three-in-one separator technology in the acidic DMF recycling and treatment system, the problem of decomposition loss of DMF during high-temperature distillation is solved, and the efficient recycling of DMF and the resource utilization of ammonium salts is achieved, which reduces the Energy consumption and solid waste generation have improved recycling rates and economic benefits.
Patent Information
- Application Number
- CN202420860422.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-24
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2034-04-24
AI Technical Summary
In industrial production, DMF decomposition losses are caused by high-temperature distillation during the recycling process of DMF. The current technology has low recovery rate, high energy consumption and waste slag, which affects the reuse and resource utilization of DMF.
A recovery and treatment system for acidic DMF was designed to treat acidic DMF solution under mild conditions through ammonia neutralization reaction, and solid, liquid and gas separation was achieved by using ammonia reactor and three-in-one separator to avoid high-temperature distillation. The use of liquid ammonia as a low-cost neutralizer has achieved resource reuse of ammonium salts and high content recovery of DMF.
It improves the recycling rate of DMF, reduces energy consumption and solid waste generation, and realizes efficient recycling of DMF and resource utilization of ammonium salts. The system structure is simple, the operating process is simple, the degree of automation is high, and the economic benefits are significant.
Smart Images
Figure CN222151986U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a recovery and processing system, in particular to a DMF hydrochloride recovery and processing system, belonging to the technical field of chemical equipment. Background Art
[0002] DMF is known as the "universal solvent" in the chemical industry because of its special physical and chemical properties - it can dissolve both organic matter and inorganic matter. At the same time, the compound can also be used as a catalyst in chemical reactions, or as a proton donor in some synthetic reactions. DMF can exist stably under normal temperature and pressure conditions, but when it is close to its boiling point (153°C), a deglycosylation reaction will occur, and it will decompose into formic acid and dimethylamine salt, or carbon monoxide and dimethylamine salt under the action of acid. The reaction formula is as follows. In the industrial production process, due to production needs, an acidic DMF solution formed by DMF and acid may be produced, such as a DMF hydrochloride solution formed by DMF and hydrochloric acid. When DMF is acidic, there will be a problem of DMF decomposition when it is recovered by high-temperature distillation. Therefore, when distilling and purifying such acidic DMF solutions, it is usually necessary to carry out the operation under reduced pressure and low temperature.
[0003]
[0004]
[0005] The main method for recovering DMF in the current industrial production process is distillation. During the distillation process, the product concentration gradually increases, and the recovery rate is low, resulting in high energy consumption and large investment costs. In the recovery device for removing formic acid in the CN107721870A patent, equipment such as a deacidification tower, a formic acid stripping tower, a condenser and a deliquescence tank are used. The system needs to raise the system temperature to 145-165°C, and the energy consumption is relatively high. CN214571625U recovers DMF through a multi-stage separator. Researchers use organic amines such as tertiary amines and tertiary amides to extract acids, or use entrainers such as tetrachloroethylene or toluene to remove acids from acid-containing DMF by azeotropic distillation deacidification. However, these processes require the introduction of foreign components such as extractants and entrainers, which affect the DMF content and reuse, and the carboxylic acid after removal still needs to be neutralized by alkali, and waste salt solid slag will still be produced. Zheng Huidong et al. proposed an innovative new process for deacidification of acid-containing DMF in "Comprehensive Utilization of Acid-containing DMF Solution [J]. Fine Chemicals, 2019, 36(12): 2457-2461". Dimethylamine was introduced into the acid-containing DMF system, and another industrial solvent N,N-dimethylacetamide (DMAC) was converted through salt formation between dimethylamine and carboxylic acid. However, the reaction raw material dimethylamine gas is volatile, difficult to preserve, and has a high price cost. Utility Model Content
[0006] Aiming at the main problems existing in the recovery of DMF in the current industrial production process, in order to avoid the problem of DMF decomposition loss when the acidic DMF solution recovers DMF at high temperature and to improve the recovery rate of DMF, the utility model provides a recovery and processing system for acidic DMF.
[0007] The specific technical solution of the utility model is as follows:
[0008] The invention discloses an acidic DMF recovery and treatment system. The acidic DMF storage tank and the ammonia buffer tank are respectively connected to a feed port of an amination reaction kettle, a discharge port of the amination reaction kettle is connected to a feed port of a three-in-one separation kettle, a liquid discharge port of the three-in-one separation kettle is connected to a neutral DMF storage tank, a solid discharge port is connected to an ammonium salt silo, a gas outlet is connected to a condenser, a liquid outlet of the condenser is connected to a neutral DMF storage tank, a gas outlet of the condenser is connected to a gas inlet of a vacuum buffer tank, and a gas outlet of the vacuum buffer tank is connected to a vacuum pump.
[0009] Further, the acidic DMF storage tank is used to hold an acidic DMF solution, which may be a solution containing DMF hydrochloride, or a mixture of other acids and DMF, wherein the other acids may be formic acid, acetic acid, sulfuric acid, nitric acid, etc. + The DMF hydrochloride is formed after DMF absorbs hydrogen chloride gas, and the DMF hydrochloride is acidic.
[0010] Furthermore, the acidic DMF storage tank is connected to the amination reaction kettle via an acidic DMF transfer pump.
[0011] Furthermore, the ammonia buffer tank is used to contain liquid ammonia.
[0012] Furthermore, the gas phase outlet of the ammonia buffer tank is connected to the ammonia reaction kettle through an ammonia feed pipeline, and the ammonia feed pipeline adopts a lower intubation pipe, and its end extends to the bottom of the ammonia reaction kettle.
[0013] Furthermore, the ammonia feed pipeline is provided with a gas flow meter, an automatic regulating valve and a switch valve, which can control the ventilation rate of the ammonia.
[0014] Furthermore, a stirring device is provided in the amination reaction kettle, and DMF hydrochloride and ammonia gas react in the amination reaction kettle. Under the stirring of the stirring device, the reaction is faster and more uniform.
[0015] Furthermore, the ammonia reactor is also provided with a pH meter for monitoring the pH in the ammonia reactor. The pH meter is interlocked with the automatic regulating valve and the switch valve on the ammonia feed pipeline. When the pH = 6.5-7.0, it indicates that the reaction is finished and the ammonia is stopped. The pH meter is interlocked with the liquid ammonia feed valve to avoid insufficient neutralization or excessive liquid ammonia. The obtained DMF can be recycled and the ammonium salt can be recycled.
[0016] Furthermore, the materials in the ammoniation reaction kettle are separated into solid, liquid and gas phases in the three-in-one separation kettle, and a filtering structure is provided in the three-in-one separation kettle to achieve solid-liquid separation.
[0017] Furthermore, a stirring device may be provided in the three-in-one separation kettle to accelerate the drying speed of the solid.
[0018] Further, the three-in-one separation kettle is provided with a nitrogen inlet, and the nitrogen inlet is connected to the nitrogen storage tank through a nitrogen pipeline. Preferably, the nitrogen inlet is arranged on the upper part of the three-in-one separation kettle. Nitrogen can enter the three-in-one separation kettle through the nitrogen pipeline, and the nitrogen can be introduced during solid-liquid separation to perform a filter press operation, and the nitrogen can also be used to supplement the pressure of the three-in-one separation kettle when the solid ammonium salt is discharged.
[0019] Furthermore, the three-in-one separation kettle is provided with a heat-insulating jacket for heating it.
[0020] Preferably, the liquid discharge port and the solid discharge port of the three-in-one separation kettle are arranged at the lower part of the three-in-one separation kettle, and the gas outlet of the three-in-one separation kettle is arranged at the upper part of the three-in-one separation kettle.
[0021] Furthermore, the condenser is one, or a condenser group formed by two or more condensers connected in series, which can be selected according to actual needs. When the amount of gaseous DMF is large and one condenser cannot achieve sufficient condensation and recovery of DMF, a multi-stage condenser can be used for processing.
[0022] Furthermore, the gas outlet of the three-in-one separation kettle is connected to the feed port of the condenser, and the bottom liquid outlet of the condenser and the liquid outlet of the three-in-one separation kettle are merged into one pipeline through a pipeline and then connected to the feed port of the neutral DMF storage tank.
[0023] Furthermore, the discharge port of the neutral DMF storage tank is connected to a neutral DMF transfer pump via a pipeline, and the neutral DMF transfer pump is used to pump the recovered neutral DMF into a required section for reuse.
[0024] The beneficial effects of the utility model are:
[0025] 1. The utility model neutralizes the acidic DMF containing DMF hydrochloride with ammonia, thereby avoiding the decomposition loss when distilling and recovering DMF, and can obtain high-content ammonium salt. The dried ammonium salt can be used in a fertilizer plant, the recovered DMF can be reused, and the ammonia dissolved in the DMF can be used as an acid binding agent. The system does not generate three wastes, has a high atomic utilization rate, and the solvent can be recycled and reused, and the ammonium salt can be recycled and reused as a resource, thereby improving the recovery rate of DMF, reducing the generation of solid waste, and having obvious economic benefits. It provides an industrial idea for recycling and treating materials of similar hydrochlorides.
[0026] 2. The utility model uses low-cost liquid ammonia. In the ammoniation reaction kettle, the liquid ammonia is vaporized into ammonia gas to react with acidic DMF to produce ammonium salt. The by-product ammonium salt is obtained by solid-liquid separation and drying by utilizing the physical property that the ammonium salt has low solubility in DMF. The system does not produce water, which does not affect the use of DMF. In particular, in reactions that require water, DMF can be recycled and reused, avoiding the operation of distillation and dehydration, and reducing energy consumption. The recovery system has a simple structure, a simple operation process, mild reaction conditions, low equipment investment, a high degree of automation, a high DMF recovery rate, and more industrial value. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 The utility model is a schematic diagram of the structure of the DMF hydrochloride recovery and processing system.
[0028] In the figure: 1. Acidic DMF storage tank; 2. Ammonia buffer tank; 3. Amination reactor; 4. Acidic DMF transfer pump; 5. Gas flow meter; 6. Automatic regulating valve; 7. Switch valve; 8. pH meter; 9. Nitrogen pipeline; 10. Three-in-one separation reactor; 11. Condenser; 12. Ammonium salt silo; 13. Neutral DMF storage tank; 14. Neutral DMF transfer pump; 15. Vacuum buffer tank; 16. Vacuum pump. DETAILED DESCRIPTION
[0029] In order to make the purpose and technical solution of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the utility model is not limited thereto.
[0030] Example 1
[0031] like Figure 1 As shown, the acidic DMF recovery and processing system of the utility model includes an acidic DMF storage tank 1, an ammonia buffer tank 2, an ammonia reaction kettle 3, a three-in-one separation kettle 10, a condenser 11, an ammonium salt silo 12, a neutral DMF storage tank 13 and a vacuum buffer tank 15.
[0032] Among them, the acidic DMF storage tank is used to hold the acidic DMF solution containing DMF hydrochloride, and the acidic DMF storage tank is connected to the feed port of the ammonia reactor through the acidic DMF transfer pump 4. The ammonia buffer tank is used to hold liquid ammonia, and the ammonia buffer tank is provided with a gas phase outlet, and its gas phase outlet is connected to the ammonia reactor through an ammonia feed pipeline. The ammonia feed pipeline is provided with a gas flow meter 5, an automatic regulating valve 6 and a switch valve 7 for controlling the ventilation rate. The ammonia feed pipeline adopts a lower intubation, and its end extends to the bottom of the ammonia reactor. Ammonia is introduced from the bottom of the ammonia reactor, which is conducive to increasing the contact area of the material.
[0033] The ammoniating reactor is used for the ammoniating neutralization reaction of the acidic DMF solution and ammonia gas. A stirring device is provided in the ammoniating reactor to increase the reaction rate and the contact area of the materials and improve the uniformity of the reaction. The stirring device can be a stirring device commonly used in industry, such as a stirring paddle, a stirring rod, etc. The ammoniating reactor is also provided with a pH meter 8 for online monitoring of the pH in the ammoniating reactor. The pH meter is interlocked with the automatic regulating valve and the switch valve on the ammonia feed line. When the pH=6.5-7.0, it indicates that the reaction is finished and the ammonia gas is stopped. The pH meter is interlocked with the liquid ammonia feed valve to avoid insufficient neutralization or excessive liquid ammonia.
[0034] Among them, the discharge port of the ammoniation reactor is connected to the feed port of the three-in-one separation reactor. After the ammoniation reaction is completed, the materials in the ammoniation reactor enter the three-in-one separation reactor for separation. The three-in-one separation reactor is provided with a liquid discharge port, a solid discharge port, a gas outlet, and a nitrogen inlet, wherein the liquid discharge port and the solid discharge port are located at the lower part of the three-in-one separation reactor, and the gas outlet and the nitrogen inlet are located at the upper part of the three-in-one separation reactor. The liquid discharge port is connected to the neutral DMF storage tank, the solid discharge port is connected to the ammonium salt silo, and the gas outlet is connected to the condenser. The three-in-one separation reactor is also provided with an insulation jacket for heating and heat preservation of the three-in-one separation reactor. A filtering structure is provided in the three-in-one separation reactor, and the filtering structure includes a filter plate and a guard plate for solid-liquid separation. The shape of the filter plate is similar to that of the three-in-one separation reactor, and it is arranged close to the side wall of the three-in-one separation reactor. A guard plate is arranged between the filter plate and the side wall of the separation reactor to protect the filter plate. After filtration, the liquid is discharged from the liquid discharge port, and the solid remains in the reactor. A stirring device may also be provided in the three-in-one separation kettle. The stirring device may have a structure commonly used in the prior art. In the solid drying stage, the drying process may be accelerated by stirring of the stirring device.
[0035] Preferably, the three-in-one separation kettle can be directly purchased from the market, such as a three-in-one filter.
[0036] The nitrogen inlet of the amination reactor is connected to the nitrogen storage tank through a nitrogen pipeline 9, which is used to pass nitrogen into the amination reactor. The nitrogen can provide pressure during solid-liquid separation to accelerate solid-liquid separation, and can also supplement the pressure of the amination reactor after the material is discharged.
[0037] Wherein, the condenser is one or a condenser group formed by two or more condensers connected in series. The gas outlet of the condenser is connected to the gas inlet of the vacuum buffer tank, and the gas outlet of the vacuum buffer tank is connected to the vacuum pump 16. The gaseous DMF enters the neutral DMF storage tank after being condensed by the condenser, and the gas coming out of the condenser is extracted by the vacuum pump through the vacuum buffer tank. The gas phase outlet of the vacuum buffer tank is connected to the vacuum pump through a pipeline, and the vacuum buffer tank can further collect a small amount of DMF that is not condensed in the gas phase, reducing damage to the vacuum pump. The vacuum pump can be a Roots vacuum pump or other types.
[0038] Preferably, the liquid outlet of the condenser and the liquid outlet of the three-in-one separation kettle are merged into one pipeline through a pipeline and then connected to the feed port of the neutral DMF storage tank.
[0039] Among them, the solid discharge port of the three-in-one separation kettle is connected to the feed port of the ammonium salt silo, and the dried ammonium salt enters the packaging equipment from the ammonium salt silo for packaging and resource recycling. The discharge port of the neutral DMF storage tank is connected to the neutral DMF transfer pump 14 through a pipeline, and the obtained neutral DMF is reused through the transfer pump.
[0040] Example 2
[0041] The acidic DMF solution containing DMF hydrochloride is recovered by the acidic DMF recovery system of Example 1, and the operation is as follows:
[0042] 1. Pour the acidic DMF solution containing DMF hydrochloride and liquid ammonia into the acidic DMF storage tank and the ammonia buffer tank respectively. DMF hydrochloride is produced after DMF absorbs hydrogen chloride gas.
[0043] 2. Transfer the acidic DMF containing DMF hydrochloride into the amination reactor through the transfer pump, start stirring, open the switch valve on the ammonia feed pipeline, control the opening of the automatic regulating valve, and detect the online pH of the ammonia reactor in real time. The reaction endpoint pH of the ammonia reactor is 6.5-7.0. When the pH is detected to be between 6-7, close the switch valve and the automatic regulating valve to stop passing ammonia.
[0044] 3. After the amination reaction is completed, the reaction materials are placed in a three-in-one separation kettle, the nitrogen pipeline is opened, and the filter is pressed into the neutral DMF storage tank, and the filter press is completed. The vacuum pump is turned on to ensure that the vacuum degree reaches 0.09-0.095MPa, and the three-in-one separation kettle is heated to between 120-125℃ and dried for 4-6h. The gas phase is condensed by the condenser and enters the neutral DMF storage tank. After the ammonium salt is dried, it is cooled to room temperature, packaged and resourced, and the neutral DMF is recycled.
[0045] Three batches of acidic DMF solutions containing DMF hydrochloride were treated according to the above method, and the results are shown in Table 1 below:
[0046] .
Claims
1. A recovery and treatment system for acidic DMF, characterized in that: The invention comprises an acidic DMF storage tank and an ammonia buffer tank, wherein the acidic DMF storage tank and the ammonia buffer tank are respectively connected to the feed port of the amination reaction kettle, the discharge port of the amination reaction kettle is connected to the feed port of the three-in-one separation kettle, the liquid discharge port of the three-in-one separation kettle is connected to the neutral DMF storage tank, the solid discharge port is connected to the ammonium salt silo, the gas outlet is connected to the condenser, the liquid outlet of the condenser is connected to the neutral DMF storage tank, the gas outlet of the condenser is connected to the gas inlet of the vacuum buffer tank, and the gas outlet of the vacuum buffer tank is connected to the vacuum pump.
2. The recycling system according to claim 1, characterized in that: The acidic DMF storage tank contains an acidic DMF solution, and the ammonia buffer tank contains liquid ammonia.
3. The recycling system according to claim 1, characterized in that: The gas phase outlet of the ammonia buffer tank is connected to the ammonia reaction kettle via an ammonia feed pipeline, and the end of the ammonia feed pipeline extends to the bottom of the ammonia reaction kettle (3).
4. The recycling system according to claim 3, characterized in that: The ammonia feed pipeline is provided with a gas flow meter (5), an automatic regulating valve (6) and an on-off valve (7).
5. The recycling system according to claim 1, characterized in that: A stirring device is arranged in the amination reaction kettle, and a pH meter is arranged on the amination reaction kettle.
6. The recycling system according to claim 1, characterized in that: The three-in-one separation kettle is provided with a filtering structure and / or a stirring device.
7. The recycling system according to claim 1 or 6, characterized in that: The three-in-one separation kettle is provided with a nitrogen inlet and / or a heat-insulating jacket, and the nitrogen inlet is connected to the nitrogen storage tank through a nitrogen pipeline.
8. The recycling system according to claim 1, characterized in that: The condenser is one, or a condenser group formed by two or more condensers connected in series.
9. The recycling system according to claim 1 or 6, characterized in that: The liquid discharge port and the solid discharge port of the three-in-one separation kettle are located at the lower part of the three-in-one separation kettle, and the gas outlet of the three-in-one separation kettle is located at the upper part of the three-in-one separation kettle.
10. The recycling system according to claim 1 or 6, characterized in that: The liquid outlet of the condenser and the liquid outlet of the three-in-one separation kettle are combined into one pipeline and then connected to the feed port of the neutral DMF storage tank; the acidic DMF storage tank is connected to the amination reactor through an acidic DMF transfer pump.