CN215505542U - Production system capable of removing volatile organic compounds in polyether polyol - Google Patents
Production system capable of removing volatile organic compounds in polyether polyol Download PDFInfo
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Abstract
The utility model discloses a production system capable of removing volatile organic compounds from polyether polyol, which comprises a stripping tower, a flash tower, an external feeding pump and a vacuum unit, wherein the stripping tower, the flash tower and the external feeding pump are sequentially connected, the stripping tower and the flash tower are both connected with the vacuum unit, and the vacuum unit is connected with waste treatment equipment. The method has strong adaptability to the existing production process of the polyether polyol, and does not need other transformation; continuous production, more energy conservation and high efficiency; no other impurities are introduced into the product, and a complex subsequent treatment process is not needed; the VOC after the removal exists in the form of waste gas, the gas quantity is low, the method is suitable for various existing waste gas treatment processes, and the process adaptability of three-waste treatment is strong.
Description
Technical Field
The utility model relates to the technical field of polyether polyol production, in particular to a production system capable of removing Volatile Organic Compounds (VOC) in polyether polyol.
Background
Polyether polyols are important raw materials for the polyurethane industry. The application fields of polyurethane products are quite wide, and the polyurethane products can be used for interior parts of automobiles, trains, ships, airplanes and the like, mattresses, sofas, chairs, bedding, carpets, building energy-saving heat-insulating materials, sealing materials and waterproof materials. The polyurethane product is used for the heat insulating material of household appliances such as refrigerator, electric appliance shell, insulating device, package, and synthetic fiber, namely spandex, which can be used for manufacturing high-grade sportswear, diving suit and the like.
With the enhancement of environmental awareness and the improvement of living standard, the environmental requirements for living goods are more and more strict, and particularly, polyurethane industrial products taking polyether polyol as a raw material are widely applied to scenes with frequent close contact with people, and the raw material with high VOC content inevitably causes heavy smell of the products, influences the use comfort and also causes harm to the environment and human bodies. Meanwhile, products with high volatile organic content and high odor also limit the application of polyether polyol products in high-end polyurethane terminal products, and have great influence on the product quality. The VOC removal of polyether polyol and the production of low-odor products become difficult problems for various large polyether polyol manufacturers, and therefore, a production system capable of removing volatile organic compounds in polyether polyol is provided.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is as follows: how to solve the difficult problems of VOC removal of polyether polyol and low-odor product production, and provides a production system capable of removing volatile organic compounds in polyether polyol.
The utility model solves the technical problems by the following technical scheme, and comprises a stripping tower, a flash tower, an external feeding pump and a vacuum unit, wherein the stripping tower, the flash tower and the external feeding pump are sequentially connected, the stripping tower and the flash tower are both connected with the vacuum unit, and the vacuum unit is connected with waste treatment equipment.
Preferably, the stripping tower comprises a deceleration section, a stripping section and a first tower kettle section, wherein the deceleration section, the stripping section and the first tower kettle section are sequentially arranged from top to bottom.
Preferably, a pre-stripping polyether inlet and a first gas phase outlet are arranged at the top of the stripping tower, pre-stripping polyether is input into the stripping tower through the pre-stripping polyether inlet, and the first gas phase outlet is connected with the vacuum unit.
Preferably, a polyether outlet and a stripping gas inlet are arranged at the bottom of the stripping tower, stripping gas is input into the stripping tower through the stripping gas inlet, and the polyether outlet is connected with the flash tower.
Preferably, the stripping column further comprises a first demister, a first feed distributor, two stages of packing, a gas phase distributor; the first demister and the first feeding distributor are both arranged in the deceleration section, and the pre-dewatering polyether inlet is connected with the first feeding distributor; the two sections of the fillers are sequentially arranged in the stripping section; the gas phase distributor is arranged in the first tower kettle section.
Preferably, the flash tower comprises a separation section, a flash section and a second tower kettle section, and the separation section, the flash section and the second tower kettle section are sequentially arranged from top to bottom.
Preferably, a polyether inlet and a first gas phase outlet are arranged at the top of the flash tower, the polyether inlet is connected with the pre-stripping polyether inlet, and the first gas phase outlet is connected with the vacuum unit.
Preferably, a post-removal polyether outlet is arranged at the bottom of the flash tower and is connected with the external pump.
Preferably, the flash tower further comprises a second demister, a second feed distributor and a section of packing, and the second demister and the second feed distributor are both arranged in the separation section; the second feed distributor is connected to a polyether inlet, and the packing is disposed in the flash section.
Preferably, the production system further comprises two groups of heat tracing assemblies, wherein the heat tracing assemblies are externally sleeved or externally heat tracing pipes, use saturated steam for heat tracing, and are respectively arranged on the stripping tower and the flash tower.
Compared with the prior art, the utility model has the following advantages: the adaptability to the existing production process of polyether polyol is strong, and other reconstruction is not needed; continuous production, more energy conservation and high efficiency; no other impurities are introduced into the product, and a complex subsequent treatment process is not needed; the VOC after the removal exists in the form of waste gas, the gas quantity is low, the method is suitable for various existing waste gas treatment processes, and the process adaptability of three-waste treatment is strong.
Drawings
FIG. 1 is a schematic flow chart of the VOC removal process for polyether polyol in example two of the present invention.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
Example one
A production system for removing VOC (volatile organic compounds) from polyether polyol comprises a stripping tower, a flash tower, an external pump and a vacuum unit;
the stripping column comprises three parts, a deceleration section, a stripping section and a column bottom section. An external sleeve or an external heat tracing pipe is arranged, and saturated steam of 0.1-1.0 MPa (G) is used for heat tracing, and in the embodiment, the saturated steam of 0.2-0.5 MPa (G) is preferably used.
Wherein the ratio of the diameter of the deceleration section to the diameter of the stripping section is 1.2: 1-2: 1. The speed reduction section is used for reducing the gas speed of the empty tower, reducing entrainment and improving the product yield, the selection of the diameter ratio is calculated and selected according to the size of entrainment liquid drops, the removal of gas phase is ensured to leave the tower body, and the polyether glycol product is left in the tower, so that the product loss is reduced.
In this example, the velocity reduction section of the stripping column contains a demister, which is used to further remove entrained mist from the gas phase. A suitable demister product can be selected by calculation from the gas-liquid phase data.
In this example, the velocity reduction stage of the stripping column comprises a feed distributor for uniformly distributing the feed polyether polyol over the column cross-section. And selecting a proper feed distributor product by calculation according to the feed amount and the tower diameter.
The stripping section of the stripping tower comprises two sections of packing, the stripping section is a main gas-liquid contact section in the stripping process, the sufficient specific surface area is favorable for gas-liquid phase separation, but the pressure drop is increased, and the stripping process is not favorable. The filler can be selected from proper porous materials, random fillers or regular fillers, and the specific surface area is 100-800 square meters per m3The preferred specific surface area is 200-500 square meters per meter3。
In this embodiment, the stripping section of the stripping column also needs to be provided with necessary internals and redistributors, such as packing press plates, support plates, redistributors, etc.
Wherein the tower bottom section of the stripping tower comprises a gas phase distributor and a tower bottom, and is used for gas phase distribution and containing polyether products.
In this example, a gas phase distributor is used to distribute the stripping gas uniformly over the column cross section. The appropriate gas phase distributor can be selected by calculation according to the gas phase quantity and the tower diameter.
In this embodiment, the tower still needs a certain liquid level height to ensure the convenience of operation.
The stripping column should contain at least 2 critical control loops, a pressure control loop and a liquid level control loop.
Wherein the pressure control circuit comprises a pressure sensor and a pressure controlled valve.
In this embodiment, the pressure sensor is located at the top of the stripping tower, and the control range is 8-20 pa (a), preferably 10-15 pa (a), and the adjustability of the pressure at the top of the stripping tower is realized by adjusting the amount of vacuumized gas.
Wherein the liquid level control loop comprises a liquid level meter and a liquid control valve.
In this embodiment, the level gauge is located the tower cauldron section, and control keeps 50% tower cauldron liquid level, and the stability of operation can be guaranteed to abundant liquid seal, prevents the UNICOM of stripper and flash column pressure, influences the normal operation of tower system.
The stripping tower at least comprises 4 material medium interfaces, a pre-stripping polyether inlet, a polyether outlet, a gas phase outlet and a stripping gas inlet.
In this example, the polyether removal inlet and the stripping gas inlet comprise suitable distribution means to ensure uniform distribution of the gas-liquid phase across the column cross-section.
The flash tower comprises three parts, a separation section, a flash evaporation section and a tower kettle section. An external sleeve or an external heat tracing pipe is arranged, saturated steam of 0.1-1.0 MPa (G) is used for heat tracing, and the saturated steam of 0.2-0.5 MPa (G) is preferably used.
Wherein the installation height of the flash tower is required to ensure that the height of a polyether inlet pipe orifice of the flash tower is lower than that of a polyether outlet pipe orifice of the stripping tower, so that the polyether inlet pipe orifice can automatically flow into the flash tower through pressure difference, a pump for conveying is reduced, and the production energy consumption is reduced.
Wherein, the separation section of the flash tower is used for separating flash evaporation gas and entrained spray.
In this example, the separation section of the flash column contains a demister for further removal of entrained mist from the gas phase. A suitable demister product can be selected by calculation from the gas-liquid phase data.
In this example, the separation section of the flash column contains a feed distributor for uniformly distributing the feed polyether polyol across the column cross-section. And selecting a proper feed distributor product by calculation according to the feed amount and the tower diameter.
Wherein the flash evaporation section of the flash evaporation tower comprises a section of filler, is mainly used for fully wetting the porous filler by polyether polyol and is favorable for flash evaporation of dissolved gas, the flash evaporation section is the main part of the flash evaporation process, the sufficient specific surface area is favorable for fully wetting the liquid phase and is favorable for flash evaporation, but the pressure drop can cause the liquid phase to be fully wettedIncreasing and adversely affecting the flash process. The filler can be selected from proper porous materials, random fillers or regular fillers, and the specific surface area is 100-800 square meters per m3The preferred specific surface area is 200 to 500 square meters per meter3。
In this embodiment, the flash evaporation section of the flash evaporation tower needs to be provided with necessary internals and redistribution devices, such as packing press plates, support plates, collectors and the like.
Wherein the tower kettle section of the flash tower is used for containing polyether products. The tower still needs a certain liquid level height to ensure the convenience of operation.
The flash tower at least comprises 2 key control loops, a pressure control loop and a liquid level control loop.
Wherein the pressure control circuit comprises a pressure sensor and a pressure controlled valve.
In this embodiment, the pressure sensor is located at the top of the flash tower, and the control range is 2-8 pa (a), preferably 2-5 pa (a), and the adjustability of the pressure at the top of the flash tower is realized by adjusting the amount of vacuumized gas.
Wherein the liquid level control loop comprises a liquid level meter and a liquid control valve.
In this embodiment, the level meter is located at the tower bottom section, and controls to maintain 50% of the tower bottom liquid level, and the sufficient liquid seal can ensure the stability of operation, ensure the sufficient net liquid level height of the outward-feeding pump, and prevent the pump from cavitation and affecting the normal operation of the tower system.
The flash tower at least comprises 3 material medium interfaces, a polyether inlet, a stripped polyether outlet and a gas phase outlet.
In this example, the polyether inlet contains suitable distribution means to ensure uniform distribution of the gas-liquid phase over the column cross-section. The post-strip polyether outlet contains a suitable vortex breaker.
The outward-feeding pump is a chemical process pump, and proper flow and lift are selected according to operation conditions.
Wherein the installation height of the external pump is ensured to meet the vacuum breaking requirement by the height from the lowest liquid level of the flash tower.
The vacuum unit has a cooling function, and is mainly used for cooling, separating and removing soluble organic matters and condensate carried in a gas phase, so that the soluble organic matters and the condensate are prevented from entering the vacuum unit and influencing the operation.
In this embodiment, the vacuum unit should select a proper amount of air extraction according to the amount of treated polyether, VOC content of products of different grades, and the amount of stripping gas, and ensure that the ultimate vacuum is not more than 2pa (a).
The working principle of the embodiment is as follows:
the temperature of polyether (polyether polyol) before stripping entering a stripping tower is 100-200 ℃, preferably 140-180 ℃, and after entering a stripping section of the stripping tower, the polyether (polyether polyol) enters a stripping section of the stripping tower, and is in countercurrent contact with stripping gas in the stripping tower, and the polyether (polyether polyol) flows out from the bottom of the stripping tower through a hydraulic control loop. Stripping column stripping gas enters from the bottom of the column, and inert gas can be used as stripping gas, in this example superheated steam and nitrogen are used. Wherein the superheated steam is preferably 0.2-1.0 MPa (G) superheated steam with the temperature of 150-250 ℃; the nitrogen gas is preferably 0.1 to 0.7MPa (G) nitrogen gas. The gas-liquid ratio range of the superheated steam of the stripping gas is 1: 5-1: 20 (mass ratio, the same below), and the gas-liquid ratio range of the nitrogen gas is as follows: 1: 10-1: 30; the preferable gas-liquid ratio ranges from 1:8 to 1:15 (superheated steam) and from 1:15 to 1:25 (nitrogen). The stripping gas enters a stripping tower, is uniformly distributed on the cross section of the tower through a gas distributor, and is in countercurrent contact with the polyether before stripping in a stripping section. The stripping tower controls the air extraction amount through a tower top pressure control loop, and extracts the stripping gas and the small molecular substances with odor dissolved in the polyether before stripping. Polyether at the bottom of the stripping tower enters the top of the flash tower and is uniformly distributed on the cross section of the flash tower through a liquid distributor, the filler in the flash tower is a porous material, the large specific surface area increases an evaporation surface, the air extraction amount and the vacuum degree are controlled through a pressure control loop at the top of the tower, the small molecular substances with odor and the stripping gas dissolved in the small molecular substances are ensured to be fully evaporated, and the property of the polyether after stripping is ensured.
Example two
As shown in figure 1, the production system for removing VOC from polyether polyol comprises a stripping tower C-101, a flash tower C-102, an outward-conveying pump P-101 and a vacuum unit P-102.
The stripping tower is provided with three sections, namely a speed reduction section 1-I, a stripping section 1-II and a tower kettle section 1-III in sequence, and at least comprises four material ports, at least comprises 1 pressure control loop 11 and 1 liquid level control loop 16.
If necessary, the stripping tower is provided with a pre-polyether inlet 18 and a gas phase outlet 17 at the top and a polyether outlet 19 and a stripping gas inlet 110 at the bottom.
Before the removal, polyether enters a stripping tower from the top of the tower, stripping gas enters the stripping tower from the bottom of the tower, and countercurrent contact is carried out in the stripping tower to remove the odorous micromolecule substances. The polyether flows from the bottom through a level control loop 16, the gas phase being withdrawn from the top.
In this example, the polyether feed temperature to the column before removal was 150 ℃.
In this example, the stripping gas was selected as superheated steam at a pressure of 1MPa (G) and a temperature of 250 ℃ in a gas-liquid ratio of 1: 10.
In this example, the first stage packing 14 and the second stage packing 15 in the stripping sections 1-II of the stripping column were each selected to have a specific surface area of 250 square meters per meter (m)3The structured packing of (1).
In this example, the ratio of the diameter of the stripper deceleration section 1-I to the stripping section 1-II is 1.5: 1.
In this embodiment, the demister 12 is a wire mesh demister made of S30408 and having a wire mesh density of 150kg/m3And porosity 0.975.
In this example, the feed distributor 13 was a nozzle type liquid distributor with a spray density of 8m3/㎡·h。
In the present embodiment, the gas phase distributor 111 selects an open gas inlet pipe.
In this example, the stripping column top pressure was controlled at 15Pa (A).
In this example, the stripper column used 0.4MPa (G) saturated steam for external heat tracing.
The flash tower is provided with three sections, namely a separation section 2-I, a flash section 2-II and a tower kettle section 2-III in sequence, and at least comprises 3 material ports, at least comprises 1 pressure control loop 21 and 1 liquid level control loop 25.
According to requirements, a polyether inlet 27 and a gas phase outlet 26 are arranged at the top of the flash tower, and a post-stripping polyether outlet 28 is arranged at the bottom of the flash tower.
Polyether enters a flash tower from the top of the tower, is fully wetted in a flash section in the tower, and is subjected to vacuum pumping to remove odorous micromolecular substances and dissolved stripping gas. The polyether after stripping flows out from the bottom of the tower through a liquid level control loop 25, and the gas phase is extracted from the top of the tower.
In this example, the filler 24 in the flash zone 2-II is selected to have a specific surface area of 250 square meters per meter3The structured packing of (1).
In this embodiment, the demister 22 is a wire mesh demister made of S30408 and having a wire mesh density of 150kg/m3And porosity 0.975.
In this example, the feed distributor 23 was a nozzle type liquid distributor with a spray density of 8m3/㎡·h。
In this example, the flash column head pressure was controlled at 3Pa (A).
In this example, the flash column used 0.4MPa (G) saturated steam for external heat tracing.
In the embodiment, the polyether after being removed is pressurized and sent to a subsequent working section by an external pump, and then is cooled and stored.
In the present embodiment, the external pump is a centrifugal pump.
In this embodiment, the gas phase pumped out by the two towers enters a vacuum unit, cooling is performed firstly, the condensate is separated, the non-condensable gas enters the vacuum unit, and the desorbed gas is finally sent to the waste gas treatment equipment for treatment.
In the embodiment, the vacuum unit is a roots + water ring vacuum unit.
The production system of the embodiment is adopted for processing, the odor of the removed polyether is detected, the concentration of characteristic substances which possibly generate odor in the product is selected for detection, and the result is shown in table 1.
Table 1 VOC removing effect table of this example
| Monool (ppm) | Formaldehyde (ppm) | Acetaldehyde (ppm) | Propionaldehyde (ppm) | Acrolein (ppm) | |
| Pre-shedding polyethers | 0.35 | 9.8 | 12.4 | 210 | 8.2 |
| Post-void polyethers | 0.01 | 0.3 | 0.4 | 0.1 | 0.5 |
Remarking: the results of the measurement of the odor-causing characteristic substances in the polyether products are selected in table 1 and are reported in ppm.
The comparison shows that the production system can effectively remove the peculiar smell in the polyether polyol product, and the characteristic substances which possibly generate the peculiar smell are all effectively removed.
In conclusion, the production system for removing VOC from polyether polyol has strong adaptability to the existing production process of polyether polyol, and does not need other transformation; continuous production, more energy conservation and high efficiency; no other impurities are introduced into the product, and a complex subsequent treatment process is not needed; the VOC after the removal exists in the form of waste gas, the gas quantity is low, the method is suitable for various existing waste gas treatment processes, and the process adaptability of three-waste treatment is strong.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (9)
1. A production system capable of removing volatile organic compounds in polyether polyol is characterized in that: including strip tower, flash column, outer pump, vacuum unit, strip tower flash column outer pump connects gradually, strip tower flash column all with vacuum unit connects, vacuum unit is connected with abandonment treatment facility.
2. The production system for removing volatile organic compounds from polyether polyol according to claim 1, wherein: the stripping tower comprises a deceleration section, a stripping section and a first tower kettle section, wherein the deceleration section, the stripping section and the first tower kettle section are sequentially arranged from top to bottom.
3. The production system for removing volatile organic compounds from polyether polyol according to claim 2, wherein: a polyether outlet and a stripping gas inlet are formed in the bottom of the stripping tower, stripping gas is input into the stripping tower through the stripping gas inlet, and the polyether outlet is connected with the flash tower; the tower top of the stripping tower is provided with a pre-stripping polyether inlet and a first gas phase outlet, pre-stripping polyether is input into the stripping tower through the pre-stripping polyether inlet, and the first gas phase outlet is connected with the vacuum unit.
4. The production system for removing volatile organic compounds from polyether polyol according to claim 3, wherein: the stripping tower also comprises a first demister, a first feeding distributor, two sections of packing and a gas phase distributor; the first demister and the first feeding distributor are both arranged in the deceleration section, and the pre-dewatering polyether inlet is connected with the first feeding distributor; the two sections of the fillers are sequentially arranged in the stripping section; the gas phase distributor is arranged in the first tower kettle section.
5. The production system for removing volatile organic compounds from polyether polyol according to claim 4, wherein: the flash tower comprises a separation section, a flash section and a second tower kettle section, wherein the separation section, the flash section and the second tower kettle section are sequentially arranged from top to bottom.
6. The production system for removing volatile organic compounds from polyether polyol according to claim 5, wherein: the top of the flash tower is provided with a polyether inlet and a second gas-phase outlet, the polyether inlet is connected with the pre-stripping polyether inlet, and the second gas-phase outlet is connected with the vacuum unit.
7. The production system for removing volatile organic compounds from polyether polyol according to claim 6, wherein: and a post-removal polyether outlet is arranged at the bottom of the flash tower and is connected with the outward-feeding pump.
8. The production system for removing volatile organic compounds from polyether polyol according to claim 7, wherein: the flash tower further comprises a second demister, a second feeding distributor and a section of packing, and the second demister and the second feeding distributor are arranged in the separation section; the second feed distributor is connected to a polyether inlet, and the packing is disposed in the flash section.
9. The production system for removing volatile organic compounds from polyether polyol according to claim 1, wherein: the production system also comprises two groups of heat tracing components, wherein the heat tracing components are externally sleeved or externally heat tracing pipes which are respectively arranged on the stripping tower and the flash tower and carry out heat tracing by using saturated steam.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115624773A (en) * | 2022-10-12 | 2023-01-20 | 万华化学集团股份有限公司 | Devolatilization device and method for removing small molecular substances and reducing odor in polyether polyol |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115624773A (en) * | 2022-10-12 | 2023-01-20 | 万华化学集团股份有限公司 | Devolatilization device and method for removing small molecular substances and reducing odor in polyether polyol |
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