Tail gas treatment and moisture absorption system in slice extraction process

Abstract

The utility model discloses a tail gas treatment and moisture absorption system in a slice extraction process in the technical field of chinlon 6 polymerization, which comprises an extraction tower, tail gas of the extraction tower is connected with a washing tower, and a spraying pump sprays water into the washing tower through a spraying pipe to clean tail gas mixed by caprolactam and water vapor. According to the device, the tail gas of the extraction tower can be recycled in a centralized manner, caprolactam monomers carried in a plurality of tail gas guide pipes of a plurality of different extraction towers can be recycled through the device, and the caprolactam monomers can be recycled even if the proportions of the tail gas are different. The caprolactam in the tail gas can be recovered together without being distinguished, the recovery is very convenient, the water consumption is small, the tail gas of the extraction tower can be cleaned up after the caprolactam in the tail gas is recovered by the washing tower, the cleaning water can be recycled, the internal crystallization of the washing tower can be avoided after the washing water is used, and the tail gas of the washing tower achieves the cleanliness of direct emission.

Description

TECHNICAL FIELD

[0001] The utility model relates to nylon 6 polymerization technical field, especially a tail gas treatment and moisture absorption system in slice extraction process. BACKGROUND

[0002] In the nylon 6 polymerization process, the slice needs to be continuously extracted, the slice after the pelletizing of the previous process is separated by water in the water separator, and then is sent to the top of the first extraction tower, the temperature in the extraction tower is about 98 DEG C, the slice flows from top to bottom under the action of gravity, fresh hot water is heated by steam, and the slice is dissolved in the hot water in the extraction tower; in order to ensure complete extraction and no residue, the slice after the extraction can be sent to the second water separator again for slice water separation, and then is extracted in the second extraction tower, and according to the process requirement, the continuous extraction process of the third and fourth effects can be carried out, and the subsequent extraction process is the same as the first extraction process; only the subsequent temperature needs to be continuously increased, and the maximum temperature is not more than 107 DEG C. After the extraction process is completed, the slice is sent to the drying system to continue the reaction in the subsequent process.

[0003] In the continuous slice extraction process, fresh hot water is used as the solvent under normal pressure, and the solvent is heated by steam and reversely washed with the slice to separate 10% of the unreacted caprolactam monomer in the raw material, the water vapor of the extraction process is directly discharged after water separation, and the high temperature of the extraction tower causes the caprolactam to dissolve in the water vapor, so that if the water vapor tail gas is directly discharged to the outside, air pollution is caused, and the water vapor tail gas needs to be concentrated and treated.

[0004] Therefore, the utility model discloses a kind of tail gas treatment and moisture absorption system in slice extraction process to solve the above problems. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a kind of tail gas treatment and moisture absorption system in slice extraction process, the tail gas of extraction tower can be concentrated and recycled, and even if multiple different extraction towers, the monomer of caprolactam carried in multiple tail gas pipes thereof can be recycled together by the device, and even if tail gas proportion is different, it can be recycled together without distinguishing, recycling is very convenient, water consumption is small, after the caprolactam in tail gas is recycled by washing tower, the extraction tower tail gas can be washed clean, and the washing water can be recycled, and after use, crystallization in the inside of washing tower can also be avoided, and the tail gas of washing tower reaches the cleanliness of direct discharge.

[0006] The utility model is implemented as follows: a kind of tail gas treatment and moisture absorption system in slice extraction process, comprising:

[0007] The extraction tower, the washing tower, the spray pump, the liquid level meter and the water supplement valve;

[0008] The front end of the extraction tower is provided with a water separator, the rear end of the extraction tower is connected with a water discharge valve, and the rear end of the water discharge valve is connected with a feeding pump;

[0009] The washing tower is internally provided with a spray pipe, water outlets of the spray pipe are arranged at the top of the inner cavity of the washing tower,

[0010] The bottom of the inner cavity of the washing tower is connected with a tail gas collecting pipe, and an air inlet of the tail gas collecting pipe is in communication with the top of the inner cavity of the extraction tower;

[0011] The bottom of the inner cavity of the washing tower is connected with a water outlet pipe, and the top of the washing tower is connected with an exhaust pipe;

[0012] The water inlet of the spray pump is connected with the rear end of the water outlet pipe, the front end of the spray pump is provided with a filter screen, the water outlet of the spray pump is connected with a filter, and the rear end of the filter is in communication with the water inlet of the spray pipe;

[0013] The liquid level meter is arranged on the washing tower, the inner cavity of the washing tower is connected with the water supplement valve through a pipeline, the water supplement valve is connected with an external desalination water pipeline, and the liquid level meter is in data connection with the water supplement valve and the spray pump.

[0014] Further, the water outlet of the spray pipe is provided with an atomizing nozzle.

[0015] Further, the filter screen is a basket filter, and the filter is a high polymer filter.

[0016] Further, the extraction tower has a plurality of extraction towers, and the extraction towers are sequentially connected in series, and the exhaust outlets at the top of the extraction towers are in communication with the tail gas collecting pipe.

[0017] Further, the outlet end of the filter is also connected with an external extraction water pipeline through a three-way valve.

[0018] The beneficial effects of the utility model are as follows: 1. The utility model can collect the tail gas of the multiple extraction towers connected in series, and the tail gas can be collected through the tail gas collecting pipe regardless of the concentration of caprolactam, and the collection is convenient;

[0019] 2. The device sprays water in the washing tower through the spray pump and the spray pipe, can effectively clean the tail gas, not only achieves the purpose of dust removal, but also can dissolve the hot caprolactam steam, so that the caprolactam is dissolved in the water mist and water droplets, thereby effectively cleaning the caprolactam in the tail gas, making the tail gas meet the emission standard, and reducing the difficulty of tail gas treatment;

[0020] 3、The device also increases the filter screen and the filter, can filter the spray water of the washing tail gas, the filter screen plays the role of particle filtering, and the filter plays the role of caprolactam crystal filtering, avoids caprolactam crystallization in the washing tower and blocks, reduces the cleaning frequency of the washing tower through the cleaning and replacement of the filter and the filter screen, and the cleaning is convenient, and the tail gas treatment time is more durable. BRIEF DESCRIPTION OF DRAWINGS

[0021] The utility model will be further explained in connection with the embodiments with reference to the drawings.

[0022] Figure 1 It is a schematic diagram of the connection relationship of the devices of the utility model.

[0023] In the drawings, the component list represented by each reference numeral is as follows:

[0024] 1-extraction tower, 11-water separator, 12-drain valve, 13-feeding pump, 2-washing tower, 21-spraying pipe, 22-water outlet pipe, 23-exhaust pipe, 24-tail gas collecting pipe, 3-spraying pump, 31-filter screen, 32-filter, 4-liquid level meter, 41-water supplement valve. DETAILED DESCRIPTION

[0025] Please refer to Figure 1 The utility model provides a kind of tail gas treatment and moisture absorption system in slice extraction process, to better understand the above technical solution, the above technical solution will be explained in detail in conjunction with the drawings of the specification and specific implementation mode.

[0026] In one specific embodiment of the technical scheme of the utility model:

[0027] It includes extraction tower 1, washing tower 2, spraying pump 3, liquid level meter 4 and water supplement valve 41;

[0028] The front end of extraction tower 1 is provided with water separator 11, the rear end of extraction tower 1 is connected with drain valve 12, the rear end of drain valve 12 is connected with feeding pump 13; the rear end of feeding pump 13 is connected with the subsequent production process of slice; feeding pump 13 can be connected with multiple extraction towers 13 in sequence, forming one-effect, two-effect and three-effect extraction towers 13, and the last extraction tower 13 needs to be connected with the drying process pipeline of slice; there are multiple extraction towers 1, each extraction tower 1 is connected in sequence, and the top exhaust port of each extraction tower 1 is communicated with tail gas collecting pipe 24. Make tail gas collecting pipe 24 parallelly connect the tail gas pipes of the connected extraction towers 1, one tail gas collecting pipe 24 can collect all the tail gas of extraction tower 1, and then centralized processing, without considering the concentration and physical state of caprolactam in tail gas, centralized recovery, reduce pollution, also can recycle caprolactam for reuse.

[0029] The spray pipe 21 is arranged inside the washing tower 2, the water outlet of the spray pipe 21 is provided with an atomizing nozzle.

[0030] The water mist and water droplets can be sprayed out, can be more fully combined with the tail gas sent by the tail gas collecting pipe 24, effectively dissolves and absorbs the caprolactam monomer in the tail gas, and can effectively capture the particulate matter, so that the particulate matter is attached to the water mist and is settled, and the purpose of filtering the caprolactam vapor tail gas is effectively achieved.

[0031] The inner cavity bottom of the washing tower 2 is connected with the tail gas collecting pipe 24, and the gas inlet of the tail gas collecting pipe 24 is communicated with the inner cavity top of the extraction tower 1;

[0032] The inner cavity bottom of the washing tower 2 is connected with the water outlet pipe 22, and the top of the washing tower 2 is connected with the exhaust pipe 23;

[0033] The water inlet of the spray pump 3 is connected with the rear end of the water outlet pipe 22, and the front end of the spray pump 3 is provided with a filter screen 31, which is a basket type filter;

[0034] The water outlet of the spray pump 3 is connected with a filter 32, the rear end of the filter 32 is communicated with the water inlet of the spray pipe 21, and the filter 32 is a high polymer filter, which filters the fine caprolactam crystal in the initial state; so as to achieve the filtering of the spray water through the filter screen 31 and the filter 32, so as to avoid the crystallization of caprolactam on the inner wall of the washing tower 2, and the filter 32 and the filter screen 31 are easier to clean and replace, and the washing workload is large after the washing tower 2 is crystallized too much, which seriously affects the tail gas treatment work of the extraction tower 1.

[0035] The outlet end of the filter 32 is also connected with an external extraction water pipeline through a three-way valve, so that the extraction with high concentration can be directly delivered to the caprolactam recovery system, which is convenient for the recycling of caprolactam, and the dissolution and absorption of caprolactam in the tail gas through the spray pump 3 and the spray pipe 21 can increase the concentration of caprolactam in the spray water, so that the caprolactam solution with higher concentration can be treated in the subsequent process, reducing the difficulty of caprolactam extraction in the subsequent process, and reducing the waste of water resources.

[0036] A liquid level meter 4 is arranged on the washing tower 2, and the inner cavity of the washing tower 2 is connected with a water supplement valve 41 through a pipeline, the water supplement valve 41 is connected with an external desalted water pipeline, and the liquid level meter 4 is connected with the water supplement valve 41 and the spray pump 3 in data, which can be controlled by a PLC controller.

[0037] It should be noted that:

[0038] 1. The exhaust gas of caprolactam is directly discharged, which causes atmospheric pollution; 2. The exhaust gas of the extraction tower 1 contains about 0.3% of monomer caprolactam which is not recycled, causing waste of production resources; 3. In the production process, due to temperature fluctuation in the extraction tower 1, a small amount of slices may be taken out and directly discharged, and it is difficult to collect these discharged slice particles in time, which will be oxidized after a long time and cannot be reused, causing the loss of production resources.

[0039] In use, the caprolactam aqueous solution is normally polymerized and pelletized by the upstream process, then enters the extraction tower 1 to extract and clean the slice particles, and then undergoes subsequent drying process to obtain clean and dry slice particle finished products.

[0040] The device processes the exhaust gas of the extraction tower 1, which contains different proportions of caprolactam steam, concentrates the mixed steam through the exhaust gas collecting pipe 24, and then transports it into the washing tower 2 to clean the mixed steam of the exhaust gas and cool the slice particles to drop into the washing tower 2.

[0041] The water in the spraying pump 3 is pumped into the spraying pipe 21 to generate water mist and water droplets, which can cool the caprolactam and water vapor in the exhaust gas, and the caprolactam will be absorbed by the water mist and fall into the washing tower 2 to form a caprolactam aqueous solution, which is then discharged through the water outlet pipe 22. The slice particles are intercepted by the filter screen 31, which not only facilitates recycling, but also facilitates cleaning and avoids mutual abrasion between the spraying pump 3 and the slice particles. The water sprayed by the spraying pump 3 is the caprolactam aqueous solution in the washing tower 2, and the filter 32 filters the caprolactam aqueous solution sent by the spraying pump 3, effectively absorbs and intercepts the fine caprolactam crystals, effectively avoids the formation of large crystals by absorbing caprolactam crystals in the washing tower 2, and effectively reduces the cleaning frequency of the washing tower 2. When the concentration of the caprolactam aqueous solution in the water outlet pipe 22 is high, the caprolactam aqueous solution can be discharged into the subsequent recovery process pipeline through the three-way valve at the rear end of the filter 32 for centralized treatment. Too dilute caprolactam water can cause large extraction workload, and the device can flexibly control the discharge direction of the caprolactam aqueous solution. When the concentration is very low, it can be used as spraying water, which is convenient for circulating water and reduces the loss.

[0042] The device also increases the water replenishment valve 41 and the liquid level meter 4. When a large amount of caprolactam aqueous solution is discharged from the washing tower 2, the liquid level meter 4 detects that the liquid level in the washing tower 2 decreases rapidly, the spraying pump 3 can be closed, and the water replenishment valve 41 can be opened to supplement clean desalted water into the washing tower 2 to supplement the dissolved water in the washing tower 2.

[0043] Although the specific embodiments of the present application are described above, those skilled in the art should understand that the specific embodiments described by us are only illustrative, not for limiting the scope of the present application, and equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present application should be covered within the scope of the claims of the present application.

Claims

1. A tail gas treatment and moisture absorption system in a slice extraction process, characterized in that, The utility model relates to a kind of water desalination system, including: Extraction tower (1), washing tower (2), spray pump (3), liquid level meter (4) and water replenishing valve (41); The front end of the extraction tower (1) is provided with a water separator (11), and the rear end of the extraction tower (1) is connected with a drain valve (12), and the rear end of the drain valve (12) is connected with a feeding pump (13); The washing tower (2) is provided with a spray pipe (21) inside, and the water outlet of the spray pipe (21) is arranged at the top of the inner cavity of the washing tower (2), The inner cavity bottom of the washing tower (2) is connected with a tail gas collecting pipe (24), and the gas inlet of the tail gas collecting pipe (24) is communicated with the top of the inner cavity of the extraction tower (1); The inner cavity bottom of the washing tower (2) is connected with a water outlet pipe (22), and the top of the washing tower (2) is connected with an exhaust pipe (23); The water inlet of the spray pump (3) is connected with the rear end of the water outlet pipe (22), and the front end of the spray pump (3) is provided with a filter screen (31), and the water outlet of the spray pump (3) is connected with a filter (32), and the rear end of the filter (32) is communicated with the water inlet of the spray pipe (21); The liquid level meter (4) is arranged on the washing tower (2), and the inner cavity of the washing tower (2) is connected with a water replenishing valve (41) through a pipeline, the water replenishing valve (41) is connected with an external desalination water pipeline, and the liquid level meter (4) is connected with the water replenishing valve (41) and the spray pump (3) in data.

2. The tail gas treatment and moisture absorption system in a slicing and extraction process according to claim 1, characterized in that: The water outlet of the spray pipe (21) is provided with an atomizing nozzle.

3. The system according to claim 1, wherein: The filter screen (31) is a basket filter, and the filter (32) is a polymer filter.

4. The system according to claim 1, wherein the system further comprises a moisture absorption system. There are multiple extraction towers (1), and each extraction tower (1) is connected in series, and the top exhaust port of each extraction tower (1) is communicated with the tail gas collecting pipe (24).

5. The system for tail gas treatment and moisture absorption in a slicing and extraction process according to claim 1, wherein: The outlet end of the filter (32) is also connected with an external extraction water pipeline through a three-way valve.

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