CN221015202U - Tail gas treatment device of polyvinyl alcohol dryer - Google Patents
Tail gas treatment device of polyvinyl alcohol dryer Download PDFInfo
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- CN221015202U CN221015202U CN202322669275.1U CN202322669275U CN221015202U CN 221015202 U CN221015202 U CN 221015202U CN 202322669275 U CN202322669275 U CN 202322669275U CN 221015202 U CN221015202 U CN 221015202U
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- tail gas
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- dust remover
- condenser
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- 239000004372 Polyvinyl alcohol Substances 0.000 title claims abstract description 81
- 229920002451 polyvinyl alcohol Polymers 0.000 title claims abstract description 81
- 239000000428 dust Substances 0.000 claims abstract description 87
- 238000004821 distillation Methods 0.000 claims abstract description 25
- 238000011084 recovery Methods 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims description 123
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 26
- 229910052757 nitrogen Inorganic materials 0.000 claims description 13
- 238000007664 blowing Methods 0.000 claims description 7
- 238000003860 storage Methods 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 abstract description 51
- 238000000034 method Methods 0.000 abstract description 40
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 132
- 239000007788 liquid Substances 0.000 description 60
- 239000000843 powder Substances 0.000 description 38
- 239000002699 waste material Substances 0.000 description 34
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 24
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 24
- 239000000463 material Substances 0.000 description 9
- 230000008901 benefit Effects 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 238000004140 cleaning Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000007789 sealing Methods 0.000 description 7
- 238000006136 alcoholysis reaction Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 229920002689 polyvinyl acetate Polymers 0.000 description 5
- 239000011118 polyvinyl acetate Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 230000005494 condensation Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000001632 sodium acetate Substances 0.000 description 4
- 235000017281 sodium acetate Nutrition 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000003513 alkali Substances 0.000 description 2
- 239000012267 brine Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000005194 fractionation Methods 0.000 description 2
- 239000010808 liquid waste Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 2
- 239000010963 304 stainless steel Substances 0.000 description 1
- 208000036828 Device occlusion Diseases 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 150000004702 methyl esters Chemical class 0.000 description 1
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- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
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- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The utility model relates to a tail gas treatment device of a polyvinyl alcohol dryer, which comprises a filter element dust remover and a coarse separation tower, wherein an air inlet of the filter element dust remover is communicated with an air outlet of the dryer, an air outlet of the filter element dust remover is communicated with a feed inlet of the coarse separation tower, the bottom of the coarse separation tower is communicated with a recovery tower, the bottom of the coarse separation tower is communicated with the recovery tower, the top of the coarse separation tower is communicated with a first condenser, the top of the first condenser is communicated with a second condenser, the bottom of the first condenser is communicated with a first distillation groove, the first distillation groove is communicated with a five-tower distillation groove, and the second condenser is respectively communicated with the five-tower distillation groove and a tail gas collecting tower. According to the utility model, the tail gas of the dryer passing through the filter element dust remover can be directly connected to the coarse separation tower for subsequent treatment, so that PVA dust in the tail gas of the polyvinyl alcohol dryer is effectively removed, the tail gas treatment process flow is shortened, and the separation of each component in the tail gas is realized, so that the energy is saved and the consumption is reduced.
Description
Technical Field
The utility model relates to the technical field of tail gas treatment of a dryer, in particular to a tail gas treatment device of a polyvinyl alcohol dryer.
Background
The alcoholysis process is to fully mix polyvinyl acetate (PVAC) methanol solution and liquid alkali with a certain concentration by a mixer, then to perform chemical reaction in an alcoholysis machine to generate a blocky polyvinyl alcohol (PVA) product, and finally to obtain a PVA finished product by crushing, squeezing and drying. The evaporated gas such as methanol and methyl acetate in the drying process is collected by a front section steam drum of the dryer, then is pumped out by a vacuum pump at the flow rate of 1500-2000m 3/h, the gas temperature is about 70 ℃, enters the lower section of a methanol condenser, is sprayed by waste liquid in a waste liquid receiving tank to remove powder entrained in the gas, and the spray liquid with the powder enters a precipitation tank. The gas enters the middle section of the methanol condenser to be in countercurrent contact with the first circulating liquid, and after condensate enters a circulating tank, the condensate is sent out in two ways by a first circulating pump: one way is sent to the waste liquid receiving tank, and the other way is cooled by the first plate type cooler and then is used as condensate in the middle section of the methanol condenser. The non-condensable gas in the middle section of the methanol condenser rises to the upper section to be in countercurrent contact with the second circulating liquid, and the condensate liquid enters the second circulating tank. Pumping part of liquid in the second circulation tank into a second plate cooler by a second circulation liquid pump, cooling by chilled brine, and dividing the liquid into two parts, wherein one part is used as second circulation liquid, and the other part is used as vacuum pump sealing liquid; the rest liquid in the two circulating tanks overflows to a circulating tank. The process flow is shown in figure 1.
Although the process can treat the tail gas of the polyvinyl alcohol dryer, the treated waste liquid contains more PVA powder. The powder in the waste liquid of the precipitation tank is taken out from the waste liquid of the squeezer and tail gas of the dryer. The powder in the first circulating tank is carried out from condensate in the middle section of the methanol condenser. The powder rate in the waste liquid is too high, so that the following three problems are brought to the whole treatment process: (1) The exhaust gas of the dryer is sprayed by waste liquid to bring the tail gas out of PVA powder for recycling, and the lower section tower plate of the methanol condenser is blocked and the exhaust transverse pipe is blocked easily due to more brought powder, so that the vacuum of the dryer is influenced, and the product quality is influenced; in addition, the transverse gas pipe and the lower section of the methanol condenser are required to be boiled out by frequent stopping, the production progress is affected, and the consumption is increased. (2) The powder is carried in tail gas of the dryer and is not treated cleanly, the powder is carried into the middle section of the methanol condenser, a large amount of PVA powder is contained in the first circulating system, the addition of the first circulating liquid and the heat exchange effect of the plate heat exchanger are affected, the subsequent tail gas recovery is affected, the consumption of circulating water and chilled water is increased, the condensation effect is poor, and the vacuum of the dryer is affected. (3) The PVA powder carried out by tail gas is recovered by waste liquid spraying, the recovered liquid returns to a precipitation tank, and the PVA powder is recovered by adding a squeezer after precipitation, so that the load of the squeezer is greatly increased, the squeezer is easily bridged, and the production stability is influenced; and PVA powder in the precipitation tank is excessive, so that the PVA powder needs to be processed by a filter press, and a large amount of materials and methanol are wasted. In addition, the loss of raw materials and products is caused, and the month loss of raw materials methanol and PVA products can be calculated from the cleaning condition of the filter press. One filter press is cleaned one day, and the cleaning filter press has approximately 200 kg of PVA wet material with the moisture content of about 50%, so that the loss of raw material methanol per month is about 1370 kg, and the loss of PVA product per month is about 3900 kg.
Therefore, a device for treating tail gas of a polyvinyl alcohol dryer is needed, and the problems that the tail gas treatment process flow of the polyvinyl alcohol dryer is long, and the treated waste liquid contains more PVA powder and is easy to cause device blockage in the prior art are solved.
Disclosure of Invention
Aiming at the defects of the prior art, the utility model aims to provide a tail gas treatment device of a polyvinyl alcohol dryer, which can effectively remove PVA dust in the tail gas of the polyvinyl alcohol dryer, shorten the tail gas treatment process flow and realize the separation of all components in the tail gas.
In order to solve the technical problems, the technical scheme of the utility model is as follows:
The utility model provides a polyvinyl alcohol desiccator tail gas processing apparatus, includes filter core dust remover, roughing tower, the gas inlet of filter core dust remover and the gas vent intercommunication of desiccator, the gas outlet of filter core dust remover and the feed inlet intercommunication of roughing tower, the tower bottom and the recovery tower intercommunication of roughing tower, the top and the second condenser intercommunication of roughing tower, the bottom and the first distillate tank intercommunication of first condenser, first distillate tank and five tower distillate tank intercommunication, the second condenser is with five tower distillate tank and tail gas collection tower intercommunication respectively.
In this way, the tail gas of the polyvinyl alcohol dryer mainly comprises gases such as methanol, methyl acetate and the like, water vapor and PVA dust, the PVA dust in the tail gas of the dryer is adsorbed in a filter element dust remover, and the powder rate in the tail gas after dust removal by the filter element dust remover is reduced to the feeding requirement of subsequent separation; introducing the tail gas into a crude separation tower for fractionation, discharging gaseous methanol and methyl acetate from the top of the crude separation tower, condensing in a first condenser, wherein the bottom liquid is mainly aqueous solution of methanol and sodium acetate, and introducing the bottom liquid into a recovery tower for recovery; introducing uncondensed gas in the first condenser into the second condenser, introducing liquid condensed in the first condenser into the first distillation tank for preliminary separation of methanol and methyl acetate, introducing liquid condensed in the second condenser into the five-tower distillation tank, introducing uncondensed gas into the tail gas collecting tower, introducing distillate in the first distillation tank into the five-tower distillation tank for further separation of methanol and methyl acetate. PVA dust in the tail gas of the dryer is removed through a filter element dust remover, water is separated from methanol and methyl acetate gas through a coarse separation tower, and methanol and methyl acetate are separated through a first distillation tank, a five-tower distillation tank, so that methyl acetate and methanol are obtained, PVA dust in the tail gas of the polyvinyl alcohol dryer is effectively removed, the tail gas treatment process flow is shortened, and separation of components in the tail gas is realized.
Further, the dryer is an apparatus for drying polyvinyl alcohol known in the art.
Further, the crude separation column is a crude separation rectifying column known in the prior art.
Further, the filter element dust remover comprises a dust remover shell, a plurality of filter cartridges are arranged in the dust remover shell, and a gas storage device communicated with the top of the filter cartridges is arranged on the side wall of the dust remover shell. Thus, by utilizing the characteristic that polyvinyl alcohol (PVA) dust is easy to be adsorbed and the principle that large particles fall down freely in a gravitational field, PVA dust in tail gas of a dryer is adsorbed in a filter cartridge, and gas is introduced into the top of the filter cartridge, so that the PVA dust adsorbed in the filter cartridge can be blown down, and the large-particle PVA dust can be caused to fall down freely, so that dust carried in tail gas of the dryer is removed.
Further, a filter element is arranged in the filter cartridge, the filter element is of a hollow cylinder structure, two layers of metal nets are arranged on the side face of the filter element, and a filter material is arranged between the two layers of metal nets; the metal net is a steel wire net, the filter material is filter paper or filter cloth, and the filter material is folded along the axial direction of the filter element. Thus, the PVA dust is convenient to adsorb, and the condensation resistance can be realized; in addition, the filter paper is folded and placed, so that the adsorption area can be increased, and the adsorption efficiency is improved.
Further, the gas storage device is a nitrogen tank, the nitrogen tank is communicated with the filter cartridge through a gas blowing pipe, and an electromagnetic valve is arranged at one end of the gas blowing pipe, which is close to the nitrogen tank. Thus, the nitrogen inlet amount is convenient to control.
Further, the outer wall of the dust remover shell is provided with a steam jacket. Thus, the steam enters the steam jacket to insulate the tail gas of the dryer, and prevent the condensation of methanol, methyl acetate and steam in the tail gas. Methanol, methyl acetate and water vapor are condensed and then adsorbed on the filter paper to influence the adsorption of the filter paper on PVA dust, and meanwhile, the water vapor falls into the dryer after being condensed to reduce the drying efficiency of the dryer. In addition, the tail gas of the dryer can be kept at a certain temperature before entering the rough separation tower, so that the subsequent separation efficiency is improved.
Further, an exhaust gas monitoring port is arranged on the air outlet of the filter element dust remover. So, be convenient for detect the PVA dust content in the tail gas after passing through the filter core dust remover and accord with the requirement.
Compared with the prior art, the utility model has the beneficial effects that:
(1) According to the method, the tail gas of the dryer after passing through the filter element dust remover is directly introduced into the coarse separation tower for subsequent treatment, so that PVA dust in the tail gas of the polyvinyl alcohol dryer is effectively removed, the tail gas treatment process flow is shortened, and the tail gas treatment effect is ensured.
(2) The powder rate of the tail gas of the dryer after passing through the filter element dust remover can be reduced to the feeding requirement of subsequent separation, thereby replacing the procedures of leaching, precipitation, filter pressing and the like in the traditional process, solving the technical problems of equipment pipeline blockage, large loss of raw material products and influence on the quality of subsequent products in the traditional process for a long time, reducing the cost of manpower resources, reducing the loss of raw material methanol and PVA (polyvinyl acetate) products, and having good energy conservation, consumption reduction and economic benefit.
(3) The filter element dust remover disclosed by the utility model has the advantages of simple structure, convenience in installation and replacement of the filter cartridge, high dust removal efficiency and convenience in recovering PVA dust by introducing nitrogen into the filter cartridge.
(4) The device has the advantages of simple structure, low cost, easy operation and control, good production stability and good treatment effect, and realizes the separation of each component in the tail gas.
Drawings
FIG. 1 is a process flow diagram of a prior art process for treating a tail gas of a polyvinyl alcohol dryer before the tail gas is introduced into a rough separation tower;
FIG. 2 is a schematic diagram of an exhaust gas treatment device of a polyvinyl alcohol dryer according to the utility model;
FIG. 3 is a flow chart of the crude distillation process of the present utility model;
FIG. 4 is a schematic view of the structure of the filter element dust collector of the present utility model;
FIG. 5 is a cross-sectional view taken along the direction A-A in FIG. 4;
FIG. 6 is a schematic top view of the filter element dust collector of the present utility model with the cover removed;
FIG. 7 is a schematic diagram of the filter element structure of the filter element dust collector of the utility model;
fig. 8 is a schematic diagram of the structure of the crude separation column of the present utility model.
Reference numerals illustrate: 1 drier, 2 filter core dust remover, 3 coarse separation tower, 20 dust remover shell, 201 lid, 202 closing plate, 21 air inlet, 22 steam inlet, 23 steam outlet, 24 support, 25 nitrogen jar, 26 blast pipe, 27 cartridge filter, 28 solenoid valve, 29 gas outlet, 271 end plate, 272 filter paper, 273 steel wire gauze, 274 shrouding, 31 tower, 32 feed inlet, 33 tower tray, 34 top of tower steam outlet, 35 tower cauldron, 36 manhole, 37 cauldron liquid outlet, 38 top of tower condenser, 4 first rectifying column, 5 second rectifying column, 6 recovery tower, 7 first distilling tank, 8 five tower distilling tank, 9 first condenser, 10 second condenser, 11 tail gas collecting tower, 12 distilling pump.
Detailed Description
The present utility model will be described in detail with reference to examples. It should be noted that, without conflict, the embodiments of the present utility model and features of the embodiments may be combined with each other.
Example 1
Referring to fig. 2-3, a tail gas treatment device of a polyvinyl alcohol dryer comprises a filter element dust remover 2 and a coarse separation tower 3, wherein the filter element dust remover 2 is respectively communicated with an exhaust port of the dryer 1 and a feed port of the coarse separation tower 3; the bottom of the rough separation tower 3 is communicated with the recovery tower 6, the top of the rough separation tower 3 is communicated with the first condenser 9, the top of the first condenser 9 is communicated with the second condenser 10, the bottom of the first condenser 9 is communicated with the first distillation tank 7, the first distillation tank 7 is communicated with the five-tower distillation tank 8, and the second condenser 10 is respectively communicated with the five-tower distillation tank 8 and the tail gas collecting tower 11.
As shown in fig. 4-6, the filter element dust remover 2 comprises a dust remover shell 20, a cover 201 is arranged at the upper end of the dust remover shell 20, an air inlet 21 is arranged at the lower end of the dust remover shell 20, an air outlet 29 is arranged at the upper part of one side of the dust remover shell 20, a plurality of brackets 24 are arranged on one side, opposite to the air outlet 29, of the dust remover shell 20, the horizontal height of each bracket 24 is smaller than that of the air outlet 29, a nitrogen tank 25 is arranged on each bracket 24, a plurality of filter cartridges 27 are arranged in the dust remover shell 20, the nitrogen tank 25 is communicated with the top of each filter cartridge 27 through an air blowing pipe 26 penetrating through the dust remover shell 20, an electromagnetic valve 28 is arranged on the air blowing pipe 26, and the electromagnetic valve 28 is positioned between the dust remover shell 20 and the nitrogen tank 25.
As shown in fig. 4, the left side of the dust collector housing 20 is provided with a steam inlet 22 and a steam outlet 23, and the steam inlet 22 is higher in level than the steam outlet 23. The filter cartridges 27 are uniformly distributed along the axial direction of the dust collector housing 20. The dust remover shell 20 is of a cylindrical structure, a sealing plate 202 is arranged in the dust remover shell 20, the sealing plate 202 is perpendicular to the axis of the dust remover shell 20, and the horizontal height of the sealing plate 202 is lower than that of the filter element end plate 271. The filter cartridge 27 is disposed through the seal plate 202, and the filter cartridge 27 is sealingly connected through the seal plate 202 to prevent dryer exhaust from leaking out of the gap into and out of the port 29. A steam jacket is provided on the inner wall of the dust collector housing 20 between the sealing plate 202 and the air inlet 21, and the steam inlet 22 and the steam outlet 23 are respectively communicated with the steam jacket.
As shown in fig. 7, a filter element is arranged in the filter cartridge 27, the filter element is in a hollow cylindrical structure, the top of the filter element is provided with an end plate 271, the bottom of the filter element is provided with a sealing plate 274, the centers of the end plate 271 and the sealing plate 274 are respectively provided with a round hole, the side wall of the filter element is provided with two layers of metal meshes 273, filter paper 272 is arranged between the two layers of metal meshes 273, and the diameter of the round holes is consistent with the diameter of the section of the inner layer of metal mesh 273. The filter core dust remover is made of 304 stainless steel, the thickness of the dust remover shell 20 is T4 steel plate thickness, as shown in FIG. 7, the number of filter cores is 7, the number of electromagnetic valves 8 is 3, and the electromagnetic valves 8 are explosion-proof pulse injection valves. The specification of the filter element is as follows: 200 x 1500, the filter core can resist high temperature and acid and alkali corrosion.
As shown in fig. 8, the coarse separation tower 3 includes a tower body 31, a plurality of trays 33 are disposed in the tower body 31, a top steam outlet 34 is disposed at the top of the tower body 31, a kettle liquid outlet 37 is disposed at the bottom of the tower body, a feed inlet 32 is disposed in the middle of the tower body, and the feed inlet 32 is communicated with the air outlet 29 of the filter element dust collector 2. An overhead condenser 38 is provided at the top of the column for condensing the overhead vapor and then refluxing. The tower body 31 is provided with a plurality of manholes 36 for overhauling the rough separation tower 3.
The tail gas treatment method of the polyvinyl alcohol dryer, which uses the tail gas treatment device of the polyvinyl alcohol dryer, specifically comprises the following steps:
s1, introducing tail gas discharged from a polyvinyl alcohol dryer into a filter element dust remover for dust removal treatment, wherein the operating pressure of the filter element dust remover is 1500Pa, the tail gas treatment capacity is 3000m 3/h, simultaneously, blowing nitrogen with the pressure of 0.2MPa into the upper part of a filter cartridge, and introducing steam with the temperature of 110 ℃ into a steam jacket;
S2, introducing the tail gas after dust removal of the filter element dust remover into a coarse separation tower for fractionation, wherein the concentration of powder in the tail gas entering the coarse separation tower is less than 30mg/m 3, and discharging an azeotrope of methanol and methyl acetate from the top of the coarse separation tower, wherein the bottom liquid of the tower is a small amount of methanol and sodium acetate aqueous solution;
S3, introducing bottom liquid of the crude separation tower into a recovery tower to recover methanol and sodium acetate, and introducing gas discharged from the tower top into a first condenser;
S4, introducing condensate in the first condenser into a first distillation tank, introducing uncondensed gas in the first condenser into a second condenser for secondary condensation, wherein the first distillation tank is mainly a liquid mixture of methanol and methyl acetate;
s5, overflowing the condensate in the second condenser to a five-tower distillation tank, and introducing uncondensed gas in the second condenser into a tail gas collecting tower;
And S6, introducing the liquid in the first distillation tank into a five-tower distillation tank to separate the methanol from the methyl acetate.
The tail gas of the polyvinyl alcohol dryer is treated by the method, and the analysis results of the crude separation tower distillate and the tower bottom liquid are shown in table 1.
TABLE 1 analysis results of crude separation column distillate and still liquid
The tail gas of the polyvinyl alcohol dryer is treated by the method in the prior art, H 2 O% is less than or equal to 0.05 by a coarse separation tower, the range of methyl acetate is 75-80%, and the content of the methyl acetate produced by the coarse separation tower kettle is less than or equal to 0.15%. As can be seen from Table 1, the method of the utility model is used for treating the tail gas of the polyvinyl alcohol dryer, and the analysis results of the crude separation tower distillate and the kettle liquid meet the process production requirements.
Comparative example 1
The method comprises the steps of adopting the existing alcoholysis process to produce PVA, respectively adopting the method of the prior art in the background art to treat dust in the tail gas of the dryer, then leading the treated dust into a coarse separation tower, and adopting the method of the utility model to directly lead the tail gas of the dryer into the coarse separation tower for tail gas treatment after passing through a filter element dust remover.
The waste liquid after the tail gas treatment of the polyvinyl alcohol dryer contains more powder in the method in the prior art, and the analysis result of the powder rate of the waste liquid is shown in table 2.
TABLE 2 analysis results of the powder fraction of waste liquid after treating the tail gas of a polyvinyl alcohol dryer by the prior art method
| Device name | Powder content of waste liquid | Methanol content of waste liquid | Waste liquid methyl acetate content | Waste liquid water content |
| Sedimentation tank | 5.11g/100ml | 76.9％ | 16.7％ | 4.53％ |
| A circulation tank | 2.36g/100ml | 68.3％ | 24.6％ | 2.28％ |
| Two circulation tanks | PVA-free powder | 71.8％ | 23.9％ | 2.88％ |
Powder in the waste liquid of the precipitation tank is brought out from the waste liquid of the squeezer and tail gas of the dryer, the waste liquid of the squeezer is brought out from the production process of producing PVA by an alcoholysis process, powder in a circulation tank is brought out from condensate in the middle section of the methanol condenser, and the powder rate in the waste liquid is too high.
The tail gas of the polyvinyl alcohol dryer is treated by the filter element dust remover, and the analysis result of the powder rate of the waste liquid is shown in table 3.
TABLE 3 analysis results of the powder rate of waste liquid after treating the tail gas of the PVA drier by using the filter element dust remover of the present utility model
| Device name | Solid content of waste liquid | Methanol content of waste liquid | Methyl ester content of waste liquid | Waste liquid water content |
| Sedimentation tank | 0.3376g/100ml | 75.2％ | 15.9％ | 4.34％ |
| A circulation tank | PVA-free powder | 68.8% | 27.2％ | 2.79％ |
| Two circulation tanks | PVA-free powder | 69.7％ | 24.4％ | 3.52％ |
The filter element dust remover is adopted to treat the tail gas of the polyvinyl alcohol dryer, and the powder in the waste liquid of the precipitation tank is only from the waste liquid of the squeezer in the production process of producing PVA by an alcoholysis process, so that the powder amount is reduced. The circulating waste liquid does not contain powder, and the tail gas of the dryer treated by the filter element dust remover is proved to be free from powder.
As can be seen from the comparison of the solid content of the waste liquid of the settling tank and the solid content of the waste liquid of the circulating tank in tables 2 and 3, the tail gas of the dryer is still more powder carried out by the tail gas of the dryer after the tail gas of the polyvinyl alcohol dryer is treated by the steam drum of the dryer in the prior art, and the tail gas of the dryer is not entrained with the powder in the tail gas of the dryer in the method of the utility model, and the tail gas of the dryer treated by the filter element dust remover can directly enter the rough separation tower for tail gas separation.
When the filter element dust remover is adopted to treat the tail gas of the polyvinyl alcohol dryer, only powder from the waste liquid belt of the squeezer exists in the settling tank in the subsequent treatment process of the tail gas of the dryer, and the cleaning frequency of the filter press is greatly reduced. The working time of the filter press is prolonged, and the original cleaning process is changed from one cleaning process in one day to one cleaning process in 5 days, so that the waste of materials and methanol is reduced. According to the cleaning of one press filter, about 200 kg of PVA wet material can be obtained, and the moisture content is more than 50%. The method of the utility model has the following benefits:
Methanol month loss: 200 x 50% × (30/5) ×0.79=474 kg.
Annual methanol saving, calculated as 10 months: (1370-474) x 10=8960 kg.
PVA feed month loss: 200X 50% × (30/5) ×1.3=780 kg.
Annual increase in PVA yield, calculated as 10 months: (3900-780) x 10=32000 kg.
Annual methanol benefits: 8960/1000×1800/t=16208.
Annual increase of PVA yield benefits: 32000/1000×15000/t= 468000/t.
The filter element dust remover is used for treating the tail gas of the polyvinyl alcohol dryer, shortens the treatment process flow of the tail gas of the polyvinyl alcohol dryer produced by an alcoholysis process, achieves the purpose of reducing energy consumption while realizing stable production, and saves electricity consumption by more than 5 ten thousand degrees per year. Annual electricity-saving cost benefit: 7.5kw×7200h×0.8 yuan/degree= 43200 yuan.
In addition, by adopting the method provided by the utility model, the waste obtained after the filter press is pressed and filtered is greatly reduced, and the waste treatment cost is reduced. In the method in the prior art, the PVA material obtained after filter pressing by the filter press contains about 50% of methanol and methyl acetate, cannot be directly sold, and needs to be dried first, and about 1 ton of steam is needed for treating one ton of PVA material.
The process of the utility model provides annual vapour savings = annual increased PVA yield x vapour price = 31.2 x 204 yuan/ton = 3868.8 yuan.
In the prior art, tail gas is condensed into liquid, then preheated to 45-65 ℃ by a heat exchanger and enters a rough separation tower for separation, and about 3 tons of steam is needed per hour. By adopting the method, the methanol and the methyl acetate gas in the tail gas directly enter the coarse separation tower for separation, thereby greatly reducing the energy consumption.
Annual saving steam benefit = saving steam usage x run time x steam price = 3t/h x 7200h x 204 yuan/ton = 267.84 ten thousand yuan.
Example 2
The tail gas treatment device of the polyvinyl alcohol dryer described in embodiment 1 is used for treating the tail gas of the polyvinyl alcohol dryer, and is characterized in that: the tail gas of the dryer enters a rough separation tower 3 for rough separation of methanol and methyl acetate, azeotrope steam of the methanol and the methyl acetate at the top of the tower enters a first distillation tank 7 after being condensed by a first condenser 9, part of the tail gas enters a second condenser 10 for cooling by chilled brine, the condensate overflows to a five-tower chute-out tank 8, and the uncondensed tail gas in the second condenser 10 enters a tail gas collecting tower 11. The condensate distilled in the first distillation tank 7 is pumped out by a distillation pump 12, one part of condensate is controlled to be the top reflux liquid, the other part is sent to the first rectifying tower 4 to be used as the feed, and the first rectifying tower further purifies and separates the methyl alcohol and the methyl acetate to obtain the methyl acetate and the methyl alcohol with higher purity. When the solvent is produced by methyl acetate, the qualified irrigation area is distilled. The tower bottom is aqueous solution of methanol and sodium acetate, and the kettle liquid is pumped into a third rectifying tower 5 of a polyvinyl acetate (PVAC) polymerization process by a crude separation rectifying tower bottom to be used as a feed. Finally, the methanol with the purity more than or equal to 98.5 percent and the methyl acetate with the purity more than or equal to 93.0 percent are obtained.
The foregoing examples are set forth in order to provide a more thorough description of the present utility model and are not intended to limit the scope of the utility model, and various modifications of the utility model, which are equivalent to those skilled in the art upon reading the present utility model, will fall within the scope of the utility model as defined in the appended claims.
Claims (5)
1. The utility model provides a polyvinyl alcohol desiccator tail gas processing apparatus, its characterized in that, includes filter core dust remover (2), thick branch tower (3), the gas inlet (21) of filter core dust remover (2) communicate with the gas vent of desiccator (1), gas outlet (29) of filter core dust remover (2) communicate with the feed inlet of thick branch tower (3), the tower bottom of thick branch tower (3) communicates with recovery tower (6), the top of thick branch tower (3) communicates with first condenser (9), the top and the second condenser (10) of first condenser (9) communicate, the bottom and the first groove (7) of distilling off of first condenser (9) communicate, first groove (7) of distilling off communicate with five tower distillation groove (8) respectively, second condenser (10) communicate with five tower distillation groove (8) and tail gas collection tower (11) respectively.
2. The tail gas treatment device of the polyvinyl alcohol dryer according to claim 1, wherein the filter element dust remover (2) comprises a dust remover shell (20), a plurality of filter cartridges (27) are arranged in the dust remover shell (20), and a gas storage device communicated with the top of the filter cartridges (27) is arranged on the side wall of the dust remover shell (20).
3. The tail gas treatment device of the polyvinyl alcohol dryer according to claim 2, wherein the gas storage device is a nitrogen tank (25), the nitrogen tank (25) is communicated with a filter cartridge (27) through a gas blowing pipe (26), and an electromagnetic valve is arranged at one end of the gas blowing pipe (26) close to the nitrogen tank (25).
4. The polyvinyl alcohol dryer tail gas treatment apparatus according to claim 2, characterized in that the outer wall of the dust remover housing (20) is provided with a steam jacket.
5. The tail gas treatment device of the polyvinyl alcohol dryer according to claim 1, wherein a tail gas monitoring port is arranged on a gas outlet (29) of the filter element dust remover (2).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322669275.1U CN221015202U (en) | 2023-09-28 | 2023-09-28 | Tail gas treatment device of polyvinyl alcohol dryer |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322669275.1U CN221015202U (en) | 2023-09-28 | 2023-09-28 | Tail gas treatment device of polyvinyl alcohol dryer |
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| CN202322669275.1U Active CN221015202U (en) | 2023-09-28 | 2023-09-28 | Tail gas treatment device of polyvinyl alcohol dryer |
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| CN (1) | CN221015202U (en) |
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