Recovery device for DMAC (dimethylacetamide) in meta-aramid polymerization byproducts

Abstract

The utility model relates to a device for recovering DMAC (dimethylacetamide) from meta-aramid polymerization byproducts, in particular to the technical field of high-performance fibers, which comprises drying equipment, gas-solid separation equipment, condensing equipment, solvent recovery equipment and a solvent delivery pump set which are connected in sequence, a gas phase outlet of the condensing equipment is connected with the vacuum buffer equipment; the condensing equipment or the vacuum buffer equipment is connected with a vacuum pump set; and a liquid phase outlet of the condensing equipment is connected with the solvent recovery equipment. According to the recovery device provided by the utility model, the solvent DMAC in the meta-aramid polymerization byproduct is efficiently recovered through reasonable design of the recovery device, the recovery rate can reach more than 99%, and meanwhile, the service life of the recovery device is obviously prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of high-performance fibers, in particular to a recovery device for DMAC in the by-products of meta-aramid polymerization, and particularly to an environment-friendly and energy-saving drying system for the by-products of meta-aramid polymerization. Background Art

[0002] At present, HCl is generated during the meta-aramid polymerization reaction and needs ammonia for neutralization reaction to generate NH4Cl. In order to ensure a salt-free polymerization system, it needs to be filtered out. However, the filtered NH4Cl contains DMAC solvent and trace oligomers. In order to achieve the goal of recovering the solvent to reduce costs and comprehensively utilize NH4Cl, it needs to be processed to recover the DMAC solvent therein and completely separate NH4Cl for by-products.

[0003] CN113355764A discloses a method for preparing colored meta-aramid fibers by a one-step method, belonging to the technical field of aramid fiber preparation, including the synthesis and spinning of colored meta-aramid polymers. The synthesis of colored meta-aramid polymers includes the following steps: dissolving m-phenylenediamine in an amide polar organic solvent; controlling the reaction temperature at -10 - 0 °C, adding a corresponding amount of 90 - 95 wt% of isophthaloyl chloride for low-temperature polycondensation reaction; adding a colored pigment, and adding the remaining corresponding amount of 5 - 10 wt% of isophthaloyl chloride to continue the low-temperature polycondensation reaction; the by-product hydrogen chloride is neutralized with alkaline earth metal oxides, hydroxides or ammonia, and the temperature of the neutralization reaction is controlled below 30 °C.

[0004] Currently, a drum dryer is mostly used for the drying of NH4Cl. The drum dryer has the following problems:

[0005] (1) The degree of automation control is low, and the labor intensity of personnel is large;

[0006] (2) Steam is used as a heat medium to heat and evaporate the DMAC solvent in the NH4Cl filter material for recovery, so a large amount of steam needs to be consumed;

[0007] (3) NH4Cl begins to decompose into NH3 and HCl when heated to 100 °C, and HCl has strong corrosiveness to equipment. Under such working conditions, the service life of the equipment is short, resulting in great investment waste;

[0008] (4) After NH4Cl is evaporated to remove the solvent, it becomes powdery. In addition, the drum dryer is not tightly sealed, which easily causes the deterioration of the working environment, thus affecting the occupational health of workers;

[0009] (5) The recovery rate of the solvent DMAC is relatively low.

[0010] In summary, the existing recovery process for the by-products of meta-aramid polymerization still has defects such as high energy consumption, serious equipment corrosion, poor working environment, and poor recovery effect. Summary of the Invention

[0011] In view of the problems existing in the prior art, the purpose of the present utility model is to provide a recovery device for DMAC in the by-products of meta-aramid polymerization, so as to solve the defects that the existing recovery process for the by-products of meta-aramid polymerization still has high energy consumption, serious equipment corrosion, poor working environment, and poor recovery effect.

[0012] To achieve this purpose, the present utility model adopts the following technical solutions:

[0013] The present utility model provides a recovery device for DMAC in the by-products of meta-aramid polymerization, and the recovery device includes:

[0014] A drying device, a gas-solid separation device, a condensation device, a solvent recovery device, and a solvent delivery pump group connected in sequence;

[0015] The gas-phase outlet of the condensation device is connected to a vacuum buffer device;

[0016] The condensation device or the vacuum buffer device is connected to a vacuum pump group;

[0017] The liquid-phase outlet of the condensation device is connected to the solvent recovery device.

[0018] The recovery device provided by the present utility model realizes efficient recovery of the solvent DMAC in the by-products of meta-aramid polymerization through reasonable design of the recovery device, and the recovery rate can reach more than 99%, and at the same time, the service life of the recovery device has been significantly improved.

[0019] As a preferred technical solution of the present utility model, the drying device includes a heating jacket and / or a hollow heating rake.

[0020] As a preferred technical solution of the present utility model, the hollow heating rake is configured with a transmission device.

[0021] As a preferred technical solution of the present utility model, the solvent recovery device is connected to an emptying receiving tank.

[0022] Preferably, the solvent recovery device is connected to the solvent secondary utilization end through the solvent delivery pump group.

[0023] As a preferred technical solution of the present utility model, the gas-solid separation device is arranged on the top of the drying device.

[0024] As a preferred technical solution of the present utility model, the solvent recovery device is configured with a liquid level gauge, a delivery pump, and an emptying valve.

[0025] As a preferred technical solution of the present utility model, the vacuum buffer device is equipped with a pressure gauge, a safety valve, a liquid level indicator and a drain valve.

[0026] As a preferred technical solution of the present utility model, the vacuum pump group is provided with a tail gas absorption system.

[0027] As a preferred technical solution of the present utility model, the gas-solid separation device is a filter bag vacuum gas-solid separation device.

[0028] As a preferred technical solution of the present utility model, the length of the filter bag in the filter bag vacuum gas-solid separation device is 0.5 - 3 m, and the diameter is 100 - 300 mm.

[0029] Compared with the prior art solutions, the present utility model has the following beneficial effects:

[0030] (1) The device provided by the present utility model has the advantages of high degree of automation control, low labor intensity, low energy consumption, small equipment corrosion, long service life, environmental protection and good working environment.

[0031] (2) When using the device provided by the present utility model to recycle the meta-aramid polymerization by-products, the recovery rate of the solvent DMAC is ≥ 99%. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the recovery device for DMAC in the meta-aramid polymerization by-products provided by the present utility model.

[0033] In the figure: 1 - drying equipment, 2 - gas-solid separation equipment, 3 - condensation equipment, 4 - solvent recovery equipment, 5 - solvent transfer pump group, 6 - vacuum buffer equipment, 7 - vacuum pump group, 8 - drain receiving tank;

[0034] I - meta-aramid polymerization by-products, II - purge gas, III - cooling circulating water, IV - tail gas washing end, V - solvent secondary utilization end, VI - drying inlet heat medium, VII - drying outlet heat medium.

[0035] The following further details the present utility model. However, the following examples are merely simple examples of the present utility model and do not represent or limit the scope of the patent protection of the present utility model. The scope of protection of the present utility model is subject to the claims. Detailed Embodiments

[0036] To better illustrate the present utility model and facilitate understanding of its technical solutions, the typical but non-limiting embodiments of the present utility model are as follows:

[0037] This embodiment provides a recovery device for DMAC in meta-aramid polymerization by-products, as Figure 1As shown, the recycling device includes:

[0038] A drying device 1, a gas-solid separation device 2, a condensation device 3, a solvent recovery device 4, and a solvent transfer pump group 5 connected in sequence;

[0039] The gas-phase outlet of the condensation device 3 is connected to a vacuum buffer device 6;

[0040] The condensation device 3 or the vacuum buffer device 6 is connected to a vacuum pump group 7;

[0041] The liquid-phase outlet of the condensation device 3 is connected to the solvent recovery device 4.

[0042] In the present utility model, the meta-aramid polymerization by-products, by mass percentage, include: 60 - 70% ammonium chloride, 20 - 30% solvent DMAC, and 1 - 3% oligomers.

[0043] Specifically, the drying device 1 includes a heating jacket and / or a hollow heating rake.

[0044] Specifically, the hollow heating rake is configured with a transmission device.

[0045] In the present utility model, with the drying device 1 of the present utility model, the meta-aramid polymerization by-products I are indirectly heated by using the drying heat medium (including the drying inlet heat medium VI and the drying outlet heat medium VII) through its jacket and the hollow shaft rake teeth, so that the ammonium chloride mixture in the meta-aramid polymerization by-products I is evaporated by conduction. The scraper agitator continuously removes the materials on the hot surface and forms a circulating flow in the container. The DMAC solvent is evaporated and then extracted by a vacuum pump; the dried ammonium chloride mixture is added from the feeding port above the cylinder body. Under the stirring of the continuously rotating rake teeth, when the material contacts the inner wall of the cylinder body, the surface is continuously updated. The dried material is indirectly heated by hot water, and the solvent component in the material is vaporized. The vaporized DMAC solvent component is timely extracted by the vacuum pump group 7. Due to the relatively high operating vacuum degree, it is beneficial to the discharge of the internal moisture and surface moisture of the dried material, and beneficial to the movement of the wet molecules of the dried material, achieving the drying purpose.

[0046] In the present utility model, the drying device 1, by way of example, is provided with a cylinder body, a feeding and discharging port, hot water inlet and outlet, a transmission system, a worm and gear quick-discharge discharging valve, etc.; further explanation is that the inside of the stirring shaft is a hollow structure, through which hot water can be introduced to increase the heat transfer area and improve the drying and separation effect of the wet material ammonium chloride; further explanation is that the motor auxiliary device is frequency conversion type, and the wet material ammonium chloride and the heating surface can be continuously updated by adjusting the rotation speed to improve the drying and separation effect of ammonium chloride. The vacuum drying machine has a compact structure, a small floor area, good sealing effect, and a large vacuum degree.

[0047] In the present utility model, the gas-solid separation device 2 can preferably be arranged at the top of the drying device 1 for filtering and intercepting large particle substances of the suction material, and the type can be selected as the filter bag form;

[0048] Exemplarily, the filter bag has a length of 0.5 - 3 m, a diameter of 100 - 300 mm, and a filtration accuracy of 5 - 50 μm; the gas-solid separation device 2 is connected to a purge gas system, and uses purge gas II such as nitrogen to purge the attached substances intercepted and filtered on the surface of the filter bag, in order to improve the service life of the filter bag and ensure the filtration effect; the purge gas system is provided with an automatic on-off valve for easy operation. The filter bag size, filtration accuracy, and nitrogen purge pressure are not limited to the above data and can be adjusted according to the specific operation of the equipment.

[0049] Specifically, the solvent recovery device 4 is connected to an emptying receiving tank 8.

[0050] Specifically, the solvent recovery device 4 is connected to the solvent secondary utilization end through a solvent transfer pump group 5.

[0051] Further, during the drying process of the meta-aramid polymerization by-product, the DMAC component rapidly vaporizes when heated, and after being filtered by the gas-solid separation device 2, it is led to a condenser through a pipeline, and the DMAC component is condensed and liquefied, and discharged from the bottom of the condenser to a solvent recovery storage tank for recycling. The DMAC solvent accumulated in the vacuum buffer device 6 will also be regularly discharged into the recovery tank. The non-condensable gas discharged from the vacuum dryer is discharged to the factory area through the vacuum buffer device 6 and the vacuum pump and enters the waste gas treatment system.

[0052] In the present utility model, the used condensing device 3 can be selected as a water-cooled condenser, which can be divided into a shell-and-tube type or a double-pipe type. The condenser is provided with circulating water inlets and outlets for transmitting cooling circulating water III.

[0053] In the present utility model, the solvent recovery device 4 is used to receive the condensed and recovered DMAC solvent component and is located below the condenser. The solvent recovery device 4 is equipped with auxiliary facilities such as a liquid level gauge, a transfer pump, and an emptying valve. The transfer pump and the liquid level gauge are jointly controlled. When the liquid level reaches the high level value, the transfer pump automatically starts to transfer to the solvent secondary utilization end V, and the pump automatically stops when it reaches the low liquid level, and the automatic control is convenient for operation.

[0054] In the present utility model, the vacuum buffer device 6 is mainly used for buffering pressure, preventing backflow, gas-liquid separation, and stabilizing the vacuum degree, and is provided with supporting auxiliary facilities such as a pressure gauge, a safety valve, a liquid level indicator, and an emptying valve.

[0055] In the present utility model, the used vacuum pump group 7 is used for negative pressure suction of the evaporated DMAC solvent component, and at the same time, a tail gas washing end IV is provided in a supporting manner. The tail gas sucked by the vacuum pump group 7 enters the tail gas washing end IV for further washing and absorption to meet the requirements of environmental protection standards.

[0056] Furthermore, the present utility model provides the usage process of the aforementioned recovery device, which specifically includes:

[0057] Feeding the meta-aramid polymerization by-product into a drying device for drying to obtain solid materials and gas;

[0058] The gas is vacuum filtered by a gas-solid separation device and then condensed by a condensing device to obtain the recovered DMAC solvent.

[0059] Among them, the drying method includes heat drying and / or heat exchange drying.

[0060] Among them, the operating temperature of the drying is 90 - 95 °C. For example, it can be 90 °C, 90.5 °C, 91 °C, 91.5 °C, 92 °C, 92.5 °C, 93 °C, 93.5 °C, 94 °C, 94.5 °C or 95 °C, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0061] In the present utility model, when adopting the heat exchange drying method, hot water is introduced into both the jacket and the shaft center of the drying device to increase the heat transfer area and improve the drying and separation effect of ammonium chloride and the solvent DMAC. After indirect heat transfer with ammonium chloride, the return water temperature is 80 - 85 °C. For example, it can be 80 °C, 80.5 °C, 81 °C, 81.5 °C, 82 °C, 82.5 °C, 83 °C, 83.5 °C, 84 °C, 84.5 °C or 85 °C, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0062] Among them, the drying time is 3 - 4 h. For example, it can be 3 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, 3.6 h, 3.7 h, 3.8 h, 3.9 h or 4 h, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0063] Among them, the absolute vacuum degree in the vacuum filtration is 90 - 99 kPa. For example, it can be 90 kPa, 91 kPa, 92 kPa, 93 kPa, 94 kPa, 95 kPa, 96 kPa, 97 kPa, 98 kPa or 99 kPa, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0064] Among them, the temperature of the condensing medium such as water used in the condensation is 20 - 35 °C. For example, it can be 20 °C, 22 °C, 24 °C, 26 °C, 28 °C, 30 °C, 32 °C, 34 °C or 35 °C, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0065] Further, in order to illustrate the good recovery effect that can be achieved by the DMAC recovery device for the by-products of meta-aramid polymerization provided by the present utility model, the following actual examples are used for illustration, which are specifically as follows:

[0066] Example 1

[0067] This example provides a specific recovery process of DMAC in the by-products of meta-aramid polymerization, which is specifically as follows:

[0068] Feed the by-products of meta-aramid polymerization into a drying device for drying to obtain solid materials and gas;

[0069] The gas is vacuum filtered by a gas-solid separation device and then condensed by a condensation device to obtain the recovered DMAC solvent.

[0070] The operating temperature of the drying is 92 °C; the drying time is 3.5 h;

[0071] The absolute vacuum degree in the vacuum filtration is 98.5 kPa;

[0072] The temperature of the condensation is 35 °C.

[0073] The indicators of the recovered product are shown in Table 1.

[0074] Example 2

[0075] This example provides a specific recovery process of DMAC in the by-products of meta-aramid polymerization, which is specifically as follows:

[0076] Feed the by-products of meta-aramid polymerization into a drying device for drying to obtain solid materials and gas;

[0077] The gas is vacuum filtered by a gas-solid separation device and then condensed by a condensation device to obtain the recovered DMAC solvent.

[0078] The operating temperature of the drying is 93 °C; the drying time is 3.8 h;

[0079] The absolute vacuum degree in the vacuum filtration is 98.7 kPa;

[0080] The temperature of the condensation is 35 °C.

[0081] The indicators of the recovered product are shown in Table 1.

[0082] Example 3

[0083] This example provides a specific recovery process of DMAC in the by-products of meta-aramid polymerization, which is specifically as follows:

[0084] Feed the by-products of meta-aramid polymerization into a drying device for drying to obtain solid materials and gas;

[0085] The gas is vacuum filtered by a gas-solid separation device and then condensed by a condensation device to obtain the recovered DMAC solvent.

[0086] The operating temperature of the drying is 90 °C; the drying time is 4 h;

[0087] The absolute vacuum degree in the vacuum filtration is 98 kPa;

[0088] The temperature of the condensation is 31 °C.

[0089] The indexes of the recovered product are shown in Table 1 in detail.

[0090] Example 4

[0091] This example provides a specific recovery process of DMAC in the meta-aramid polymerization by-product, which is as follows:

[0092] The meta-aramid polymerization by-product is fed into a drying device for drying to obtain solid materials and gas;

[0093] The gas is vacuum filtered by a gas-solid separation device and then condensed by a condensation device to obtain the recovered DMAC solvent.

[0094] The operating temperature of the drying is 95 °C; the drying time is 3 h;

[0095] The absolute vacuum degree in the vacuum filtration is 99 kPa;

[0096] The temperature of the condensation is 20 °C.

[0097] The indexes of the recovered product are shown in Table 1 in detail.

[0098] Table 1

[0099] Moisture content of solid material / % Solvent recovery rate / % Example 1 0.10 99.5 Example 2 0.09 99.6 Example 3 0.08 99.7 Example 4 0.07 99.8

[0100] As can be seen from Table 1, the recovery device provided by the present utility model realizes the efficient recovery of the solvent DMAC in the meta-aramid polymerization by-product through the reasonable design of the recovery device, and the recovery rate can reach more than 99%. At the same time, the service life of the recovery device has been significantly improved.

[0101] The preferred embodiments of the present utility model have been described in detail above. However, the present utility model is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present utility model, various simple modifications can be made to the technical solutions of the present utility model, and these simple modifications all belong to the protection scope of the present utility model.

[0102] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present utility model will not separately describe various possible combination methods.

[0103] Furthermore, any combination can be made among the various different embodiments of the present utility model, as long as it does not violate the idea of the present utility model, and it should equally be regarded as the content disclosed by the present utility model.

Claims

1. A recovery device for DMAC in the by-products of meta-aramid polymerization, characterized in that, The recovery device includes: A drying device, a gas-solid separation device, a condensation device, a solvent recovery device, and a solvent transfer pump group connected in sequence; The gas-phase outlet of the condensation device is connected to a vacuum buffer device; The condensation device or the vacuum buffer device is connected to a vacuum pump group; The liquid-phase outlet of the condensation device is connected to the solvent recovery device.

2. The recovery device according to claim 1, wherein, The drying device includes a heating jacket and / or a hollow heating rake.

3. The recovery device according to claim 2, characterized in that The hollow heating rake is configured with a transmission device.

4. The recovery device according to claim 1, characterized in that, The solvent recovery device is connected to an evacuation receiving tank; The solvent recovery device is connected to a solvent secondary utilization end through a solvent transfer pump group.

5. The recovery device according to claim 1, characterized in that, The gas-solid separation device is arranged at the top of the drying device.

6. The recovery device according to claim 1, wherein, The solvent recovery device is configured with a liquid level gauge, a transfer pump, and an evacuation valve.

7. The recovery device according to claim 1, characterized in that, The vacuum buffer device is configured with a pressure gauge, a safety valve, a liquid level indicator, and an evacuation valve.

8. The recovery device according to claim 1, wherein, The vacuum pump group is provided with a tail gas absorption system.

9. The recovery device according to claim 1, characterized in that, The gas-solid separation device is a filter bag vacuum gas-solid separation device.

10. The recovery device according to claim 9, characterized in that, In the filter bag vacuum gas-solid separation device, the length of the filter bag is 0.5 - 3 m, and the diameter is 100 - 300 mm.

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