CN100427522C - Method and device for removing free formaldehyde in urea-formaldehyde resin - Google Patents
Method and device for removing free formaldehyde in urea-formaldehyde resin Download PDFInfo
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- CN100427522C CN100427522C CNB2006100123806A CN200610012380A CN100427522C CN 100427522 C CN100427522 C CN 100427522C CN B2006100123806 A CNB2006100123806 A CN B2006100123806A CN 200610012380 A CN200610012380 A CN 200610012380A CN 100427522 C CN100427522 C CN 100427522C
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Abstract
The present invention relates to a method for removing free formaldehyde in urea-formaldehyde resin, which comprises the following steps: a casing of a rotating packed bed is preheated to 50 to 80 DEG C; the rotating packed bed is started, and the rotation speed is adjusted to 200 to 2500 rpm; the urea-formaldehyde resin which is preheated is conveyed into the rotating packed bed; meanwhile, gas (steam) stripping gas is guided into the rotating packed bed from a gas (steam) inlet of the rotating packed bed, wherein the free formaldehyde is diffused to the gas (steam) stripping gas to be carried away by the gas; the gas (steam) stripping gas is air or steam or nitrogen. More than 95% of free formaldehyde in the urea-formaldehyde resin can be removed by the method of the present invention. Industrial steam is used as the gas medium of the method of the present invention, or air or nitrogen is directly guided into the rotating packed bed; thus, the technology cost is largely reduced, and the treating capacity is large. The equipment of the present invention for removing free formaldehyde in urea-formaldehyde resin has the advantages of simple structure and easy operation; compared with the prior art, the rotating packed is used for removing free formaldehyde in urea-formaldehyde resin, and thus, the method of the present invention has the advantages of high removing efficiency, less energy consumption, simple technological processes, simple and convenient operation and operation stop, etc.
Description
Technical field
The present invention relates to a kind of equipment that removes the method for free formaldehyde in the urea-formaldehyde resin and realize this method.
Background technology
Urea-formaldehyde resin is to be basic raw material with formaldehyde and urea, a kind of thermosetting resin that obtains by chemical addition, polycondensation.Chemical reaction in the urea-formaldehyde resin building-up process is very complicated, traditional theory is thought and mainly is divided into two stages: the fs is the addition reaction stage, promptly under neutrality or weak basic condition, urea and formaldehyde carry out hydroxymethylation and generate polycondensation intermediates such as stable monomethylolurea and methylolurea; Subordinate phase is that polycondensation is the resinifying stage.Generation has methene key or the alternately repeated high molecular polymer of methylene ether link.China's produced in conventional processes urea-formaldehyde resin, the mol ratio of formaldehyde and urea are 1.6-2.0: 1, and this mol ratio formaldehyde excess quantity is big, free formaldehyde content height in the product; In the fs addition reaction is reversible in the aqueous solution, and when positive reversed reaction reached balance, total some monomer formaldehyde existed in the reaction system; Also have side reaction in synthetic urea-formaldehyde resin process, form methylene ether, hemiformal etc., they can decomposition discharge a small amount of formaldehyde to thermally labile in the resin use; In addition timber this under the damp and hot situation and urea-formaldehyde resin adhesive is solidifying, also can discharge formaldehyde in the hot pressing, but this accounts for the very little part of burst size.So, release formaldehyde in the process of using the wood-based plate produced by urea-formaldehyde resin adhesive such as woodwork plate, many plywood, mainly be since in the urea-formaldehyde resin free formaldehyde too high due to.But,, thereby still be widely used in house decoration and the wood-based plate industry because of advantages such as the urea-formaldehyde resin adhesive raw material are easy to get, cost is low, bonding strength is high, set time is short.Because a large amount of uses of house decoration and artificial board cause indoor formaldehyde concentration too high, stimulate people's eye, nose and larynx consumingly, seriously endanger the healthy of people.
At present, the main method that reduces free formaldehyde in the urea-formaldehyde resin is also used formaldehyde-trapping agent, is rationally selected solidifying agent and dewatering process etc. for use except that the prescription and synthesis technique that improve urea-formaldehyde resin.Though these methods play great role to reducing free formaldehyde, all belong to " aftertreatment " method, fundamentally do not remove the free formaldehyde that urea-formaldehyde resin contains.In addition, when using formaldehyde-trapping agent, there is degradation defective under the tack of the viscosity, package stability and the glue that make urea-formaldehyde glue.Also there are many deficiencies in other method that reduces free formaldehyde in the urea-formaldehyde resin.In addition, a difficult problem that removes in the urea-formaldehyde resin free formaldehyde is that the viscosity of high molecular polymerization system of urea-formaldehyde resin is bigger, the long-chain of high molecular polymer has the constraint effect to the diffusion motion of small molecules free formaldehyde, and the viscosity pole the earth of system has limited the diffusion of free formaldehyde monomer in polymkeric substance.
Summary of the invention
The present invention is directed to above-mentioned the deficiencies in the prior art, the method that has proposed to carry with gas (vapour) under a kind of super gravity field condition of utilizing rotary packed bed high speed rotating to produce removes the method for free formaldehyde in the urea-formaldehyde resin and the equipment of realizing this method.
The method that removes free formaldehyde in the urea-formaldehyde resin of the present invention comprises the steps: rotary packed bed shell is preheating to 50～80 ℃; Open rotary packed bed and rotating speed is transferred to 200～2500rpm; With the urea-formaldehyde resin after the preheating send into rotary packed bed in; Simultaneously gas (vapour) being carried gas introduces from rotary packed bed inlet mouth; Free formaldehyde wherein is diffused into gas (vapour) and carries in the gas and being taken away by gas, and it is air or water vapour or nitrogen that described gas (vapour) is carried gas.
Described air or nitrogen during as the gas stripping gas body gas-liquid volume ratio of itself and urea-formaldehyde resin be 500-1200m
3Standard volume gas/m
3Liquid.Water vapour is during as the gas stripping gas body, and the gas-liquid volume ratio of itself and urea-formaldehyde resin is 0.5-100m
3(standard volume) gas/m
3
The described method that removes free formaldehyde in the urea-formaldehyde resin, wherein the preheating heat temperature of urea-formaldehyde resin is 50～80 ℃; It is 80-120 ℃ air or nitrogen or water vapour that described gas (vapour) is carried gas; Described gas (vapour) is proposed gas and urea-formaldehyde resin adverse current or cross-flow in rotary packed bed and is contacted.
The described method that removes free formaldehyde in the urea-formaldehyde resin, it is 100-120 ℃ wherein with the urea-formaldehyde resin temperature, pressure be introduce after the water vapour of 0.25-0.35Mpa directly is preheated to 80-110 ℃ rotary packed bed in, described gas stripping gas body is normal temperature or is lower than 120 ℃ air or nitrogen, and described gas (vapour) is proposed gas and urea-formaldehyde resin adverse current or cross-flow in rotary packed bed and spun and touch.
The described equipment that removes the method for free formaldehyde in the urea-formaldehyde resin, comprise one rotary packed bed, at this rotary packed bed shell insulation jacket is arranged, toothed gear pump is communicated with rotary packed bed liquid distributor by the resin well heater, the other end of described toothed gear pump links to each other with the urea-formaldehyde resin head tank, rotary packed bed inlet mouth links to each other with gas source, the direct emptying in air outlet or link to each other with vacuum pump.
The described equipment that removes urea-formaldehyde resin middle reaches formaldehyde, gas source wherein are air compressor or Nitrogen plant.
The described equipment that removes free formaldehyde in the urea-formaldehyde resin is provided with gas-heating apparatus between air compressor or Nitrogen plant and inlet mouth.
The described equipment that removes free formaldehyde in the urea-formaldehyde resin, wherein gas source is the water vapour producer.
The described equipment that removes in the urea-formaldehyde resin free formaldehyde is in the filler both sides, rotary packed bed inner casing is provided with the gas baffle ring.
The method that removes in the urea-formaldehyde resin free formaldehyde of the present invention utilizes that liquid can be torn into the characteristics of form as thin as a wafer such as liquid film, brin under the hypergravity condition, urea-formaldehyde resin is introduced overweight machine, making that free formaldehyde discharges to greatest extent and diffuses to from other direction in the resin enters the gas of overweight machine, and this method can make that the free formaldehyde more than 95% removes in the urea formaldehyde.At water-bath chuck of outer setting of overweight machine, make to keep optimum temperature during the whole device busy, help resin moving and from device, discharging in overweight machine rotating bed.Used gaseous media adopts industrial steam or direct introducing air or nitrogen in the method for the present invention, makes the technology cost reduce greatly.Treatment capacity is bigger simultaneously.
The equipment that removes in the urea-formaldehyde resin free formaldehyde of the present invention, simple in structure, easy to operate, compared with prior art, remove advantages such as formaldehyde has the decreasing ratio height in the urea-formaldehyde resin, energy consumption is little, flow process is simple, the start-stop car is easy with rotary packed bed.
Description of drawings
Fig. 1 is the Processes and apparatus schema that removes free formaldehyde in the urea-formaldehyde resin
Fig. 2 is horizontal rotary packed bed structural representation
Fig. 3 is horizontal rotary packed bed internal gas shelves ring
Fig. 4 is the A-A view of Fig. 3
The rotary packed bed 16-liquid exit of the logical atmosphere 4-air outlet of 1-head tank 2-resin under meter 3-5-liquid-inlet 6-water-bath outlet 7-insulation jacket 8-liquid distributor 9-water-bath inlet 10-inlet mouth 11-toothed gear pump 12-steam inlet 13-resin well heater 14-vacuum pump 15-17-airheater 18-gas blower 19-finished product jar 20-water circulating pump 21-surge tank 22-gas baffle ring 23-filler among the figure
Embodiment
Below to method of the present invention and realize that the equipment of this method elaborates.
The characteristic of urea-formaldehyde resin is the viscosity height, and is mobile poor, and wherein free formaldehyde is difficult for spreading under the normal temperature.Urea-formaldehyde resin belongs to a kind of hot-setting adhesive again, and heat-up time is long or temperature is too high, all can quicken the further polycondensation of urea-formaldehyde resin, resin is become sticky or hardening and lose using value.Must control Heating temperature and heat-up time when therefore carrying out technological design.At first urea-formaldehyde resin is preheated to 50-80 ℃ in the resin well heater in the processing step of the present invention, the urea-formaldehyde resin under this temperature can not produce sex change substantially but the viscosity of liquid is decreased, and is convenient to carry.Next step enters rotary packed bed interior being rapidly heated also to be beneficial to resin in addition.In the rotation filler during urea-formaldehyde resin introducing after will heating then is rotary packed bed, carry out gas (vapour) with 100-120 ℃ of air or steam and carry; The present invention also can directly send into water vapour in the urea-formaldehyde resin well heater, water steam-heated cal(l)andria urea-formaldehyde resin be transported to after 100-110 ℃ rotary packed bed in, with normal temperature or introduce rotary packed bed gas less than 120 ℃ of air and carry.
The core of present method is to adopt rotary packed bed technology: remove under the centrifuge field (reaching more than 400 times of universal gravity constant) that the rotary packed bed rotation of technology utilization of free formaldehyde in the urea-formaldehyde resin produced, thinning of liquid film, drop diminish, and produce huge phase interface; The renewal rate of liquid film also is greatly improved; Simultaneously because urea-formaldehyde resin is subjected to the effect of shearing force, liquid " thinning ".These all help the diffusion of free formaldehyde in the resin; Through moment high temperature, methylol and methyne ehter bond decomposes discharge formaldehyde to urea-formaldehyde resin in rotary packed bed.The formaldehyde that diffuses out in formaldehyde that decomposes produces and the urea-formaldehyde resin enters in the gas phase together, is taken away by gas (vapour) body.
The rotating speed of described rotating bed filler is comparatively suitable at 200-2500rpm.Rotating speed is crossed when low, because the viscosity of resin is difficult to form the renewal rate of fluid film and liquid film more greatly in the rotation filler slower, the decreasing ratio of formaldehyde can reduce like this.When rotating speed is higher than 2500rpm, enters rotary packed bed urea-formaldehyde resin and thrown away very soon, in rotary packed bed the residence time too short, the formaldehyde removal effect is not good.
The volume ratio that enters rotary packed bed air or nitrogen gas and urea-formaldehyde resin is at 500-1200m
3(standard volume) gas/m
3Liquid mainly determines according to the free formaldehyde content in running cost and the urea-formaldehyde resin.If as stripping gas, adopt 100-120 ℃ of steam gas with water vapour, gas-liquid volume ratio is 0.5-100m
3(standard volume) gas/m
3
Above-mentioned urea-formaldehyde resin and high-temperature gas adverse current or cross-flow in the rotating bed filler contact, and the temperature of urea-formaldehyde resin is increased to 80-100 ℃ rapidly, and when adopting vacuum pump, because the suction function of pump, absolute pressure is lower in the system.The fast updating of high temperature, low pressure and liquid phase upper layer in the rotating bed filler helps the free formaldehyde molecule and spreads rapidly to gas phase; The time that urea-formaldehyde resin stops in the rotation filler is shorter, and the high temperature of moment can not exert an influence to the character of urea-formaldehyde resin; Simultaneously, urea-formaldehyde resin is through the pyroprocessing of moment, deviates from smoothly on the one hand by methylol and methyne ehter bond and decomposes the formaldehyde that produces, and the resin behind the moment high temperature is deposited stablely on the other hand, can also reduce the dewatering process time.
Rotary packed bed bath temperature is controlled at 50-80 ℃, makes whole rotary packed bed wall keep optimum temperature during operation, help resin and flow downward and from wherein discharging fast at rotary packed bed wall; Also reduced in rotary packed bed and urea-formaldehyde resin temperature after high-temperature gas contacts, prevented that continuous high temperature from making the urea-formaldehyde resin sex change.
Comprise one rotary packed bed 15 with reference to the accompanying drawing 1-4 equipment that removes free formaldehyde in the urea-formaldehyde resin of the present invention, install an insulation jacket 7 around it additional, the water-bath inlet 9 of chuck 7, water-bath outlet 6 connect the surge tank 21 of water circulating pump 20 and band heating installation respectively.Urea-formaldehyde resin head tank 1 links to each other with resin well heater 13 by a toothed gear pump 11, and resin well heater 13 communicates with rotary packed bed 15 liquid distributor 8.Rotary packed bed liquid exit 16 connects finished product jar 19.Rotary packed bed 15 air outlet 4 links to each other with vacuum pump 14 or directly logical atmosphere.Rotary packed bed inlet mouth 10 communicates with steam generator or air, nitrogen gas generator and preheater thereof.If high-temperature resin directly into rotary packed bed, then can directly be sent air or nitrogen into the gas inlet.
Concrete operations: the heating unit of starting surge tank 21, trough inner water is heated to 50-80 ℃, start water circulating pump 20, hot water flows at rotary packed bed 15 external insulation chuck 7 and 21 of surge tanks, with rotary packed bed 15 the heating and maintain in the said temperature scope, open rotary packed bed 15 and adjust the frequency control motor rotating speed, the speed adjustable range of this motor can reach 200-2500rpm.
During the charging of urea-formaldehyde resin normal temperature, (open vacuum pump 14 during vacuum operating, atmospheric operation needn't start), starter receiver pump 11 is sent into 13 preheatings of resin well heater with pending urea-formaldehyde resin from head tank 1, make the temperature of resin be elevated to 50-80 ℃, the urea-formaldehyde resin of preliminary preheating is entered liquid distributor 8 by rotary packed bed 15 liquid-inlet 5.Liquid distributor 8 is sprayed at rotary packed bed layer inner edge near at ring-like rotary packed bed inwall symmetry cloth liquid with urea-formaldehyde resin; Gas blower 18 is sent into a preheating temperature 80-120 ℃ air rotary packed bed, and gas radially or axially contacts with urea-formaldehyde resin by filling batch, (or directly feed water vapor in rotary packed bed gas inlet).
This technology can also be with the raw material urea-formaldehyde resin after resin well heater 13 usefulness 0.25-0.35MPa water vapour direct heating be to 100-120 ℃.Send into rotary packed bed; Gas blower 18 will be lower than 120 ℃ air or nitrogen and send into rotary packed bed 15 and carry out gas and carry.(open vacuum pump 14 during vacuum operating earlier, atmospheric operation needn't start, but need open logical atmosphere 3 valves of rotary packed bed 15 air outlets 4)
Gas is entered in rotary packed bed 15 by inlet mouth 10 along rotary packed bed 15 circular wall, axially or radially 4 discharges or finds time through vacuum pump 14 from the air outlet by rotary packed bed 15 backs.Under action of centrifugal force, resin liquid is thrown toward outer shroud from interior ring filler, flows to the bottom along rotary packed bed inwall then and enters finished product jar 19 through liquid exit 16 outflows.
Of the present inventionly gas baffle ring 22 also is installed in rotary packed bed.Rotation filler 23 in rotary packed bed is when handling the high liquid of viscosity, and liquid will form one deck liquid film attached on the wall after throwing away filler, for the smoothness that ensures liquid is passed through, must increase the distance of rotating bed and wall.After but distance increased, if do not increase the interception parts, most of gas will flow through from the annular space at rotary packed bed edge and not pass rotary filler layer.After increasing the gas baffle ring, will guarantee that most of gas passes filler 23, to ensure abundant contact in cross-flow or adverse current rotating bed gas-liquid in service.Simultaneously rotary packed bed being in operation has a spot of urea-formaldehyde resin and enters in rotary packed bed inlet pipe and the escape pipe both sides cavity, flow downward, be pooled at last between rotary packed bed inner shell bottom and the gas shelves ring, therefore open outage in the bottom of gas shelves ring, guarantee that the liquid of rotary packed bed both sides is flowed in the intercepting basin.Gas will guarantee that gas is progressively increasing along radial distribution in the circulation of packing layer along the rotation of rotary packed bed wall after with tangential admission.Guarantee even gas distribution, prevented gas " short circuit " phenomenon;
Above-mentionedly rotary packed bedly both can realize gas liquid cross-flow or counter-current operation,, take out the gas baffle ring of inlet end simultaneously, just can do the rotary packed bed use of adverse current at blind plate of the Ge Jia up and down of packing layer.Traditional horizontal rotary packed bed not smooth drawback of liquid stream that exists, handle liquid measure be prone to when big fluid accumulation in rotary packed bed bottom so that " flooding machine " phenomenon of submergence rotating bed bottom filler, if taking place, " flooding machine " phenomenon will reduce rotary packed bed efficient, stop when serious and reduce rotary packed bed rotation, rotate the energy consumption surge this moment, rotating speed descends, and process worsens.United States Patent (USP) (U.S Patetent 4382045) is installed the rotation inducer in rotary packed bed inner walls, but gas-liquid is sealed liquid exit thereby is difficult to and proves effective when liquid measure or rotating speed are high.Of the present invention horizontal rotary packed bed in the lower case perforate, simultaneously the bottom is provided with intercepting basin, makes from the rotary packed bed liquid that throws away dirtyly along super inwall, enters in the intercepting basin.Thereby traditional horizontal rotary packed bed " flooding machine " phenomenon of avoiding.
This process gas (vapour) is carried gas and is adopted water vapor or air.When at atmospheric operation, gas (vapour) is carried gas and can be selected temperature at 90-120 ℃ of warm air, nitrogen or water vapour; When vacuum pumping, the high more diffusion that helps formaldehyde monomers in the urea-formaldehyde resin more of vacuum tightness, so when using air or nitrogen gas to put forward, needn't consider the problem of vacuum tightness size, as long as economic problems of aspiration rate, final vacuum and the running cost of consideration and employed vaccum-pumping equipment.Under the condition that vacuumizes a spot of moisture help in the urea-formaldehyde resin free formaldehyde monomers in the nucleation of resin inside, condense, grow up and spread, but must consider the vapor pressure of use and the relation of vacuum pump aspiration vacuum level when using the water vapor stripping, vapor temperature is relevant with vacuum tightness, vacuum tightness is higher, the temperature of required steam is lower, therefore use industrial steam gas (vapour) must make in carrying the pressure of operation can not be too low, generally need remain on 0.25-0.35Mpa.If adopt high vacuum, high-temperature steam (120-140 ℃) gas (vapour) to carry urea-formaldehyde resin, not only can bring redundant moisture into to urea-formaldehyde resin, and since in the steam vaporization of water increased the problem of the load and the rotary packed bed entrainment of vacuum pump.Therefore generally when using steam stripped, do not vacuumize or vacuum tightness lower.
If when adopting water vapour heating urea-formaldehyde resin,, wherein contained large quantity of moisture, if re-use the load that the water vapour stripping can increase vacuum pump because heated urea-formaldehyde resin temperature is higher.So with air or nitrogen carry out gas carry comparatively suitable.
Embodiment 1
Remove free formaldehyde monomers in the urea-formaldehyde adhesive: the pending hot setting urea-formaldehyde adhesive of technology amount is 0.5m
3/ h, free formaldehyde content are 2.52% (mass ratio).
At first urea-formaldehyde adhesive is adopted heating in water bath that the temperature of resin is elevated to 70 ℃, open rotary packed bed water-bath and keep organism temperature about 70 ℃; Open rotary packed bed, regulating rotary packed bed rotor speed by frequency transformer is 2800r/min, treat rotary packed bed stable back (about two minutes), in rotary packed bed, feed tackiness agent through preheating, simultaneously feeding is 100-110 ℃ a warm air through the temperature of preheating to rotary packed bed in, progressively tolerance is enlarged to 400m by variable valve
3/ h.The free formaldehyde content of treated urea-formaldehyde resin is reduced to less than 0.1% (specific targets see the following form).
Treated urea-formaldehyde glue technical indicator is:
| Index name | Index | The method of inspection |
| Outward appearance | The even liquid of colourless, white inclusion-free | GB/T14074.1 |
| Solid content % | 55-56 | GB/T14074.5 |
| PH value | 7.0-8.5 | GB/T14074.4 |
| Free formaldehyde % | 0.10％ | GB/T14074.16 |
| Viscosity (MPa.s) | 160.0-500.0 | GB/T14074.3 |
| Set time (s) | ≤65 | GB/T14074.7 |
| Adaptive phase (h) | ≥4.0 | GB/T14074.8 |
With the wood-based plate of its processing, detect by national wood-based plate quality supervision and test center, every technical indicator all meets and is better than state compulsion standard (GB18580-2001).
Embodiment 2
Remove free formaldehyde monomers in the urea-formaldehyde resin: the pending cold solid urea-formaldehyde adhesive amount of technology is 1m
3/ h, free formaldehyde content are 1.21% (mass ratio).
At first urea-formaldehyde resin is adopted heating in water bath that the temperature of resin is elevated to 55 ℃; Open rotary packed bed water-bath and keep organism temperature about 55 ℃; Open vacuum pump; Open rotary packed bed, regulating rotary packed bed rotor speed by frequency transformer is 2500r/min, treat rotary packed bed stable back (about two minutes), in rotary packed bed, feed urea-formaldehyde resin through preheating, in rotary packed bed, feed the water vapor of 0.07MPa simultaneously, progressively tolerance is enlarged to 5m by variable valve
3/ h.And the vacuum tightness of keeping inside is 10-15kPa; The free formaldehyde content of treated urea-formaldehyde resin is reduced less than 0.08%.
Embodiment 3
Remove free formaldehyde monomers in the urea-formaldehyde resin: the pending urea-formaldehyde resin amount of technology is 1000kg/h, and free formaldehyde content is 3.13% (mass ratio).
Process and urea-formaldehyde resin dewatering process that present embodiment removes free formaldehyde monomers in the urea-formaldehyde resin unite two into one.The blowing that top connects reactor cuts down, and opens vacuum pump; Open rotary packed bed water-bath circulation, keep organism temperature about 70 ℃-80 ℃; Open rotary packed bed, regulating rotary packed bed rotor speed by frequency transformer is 1200r/min, treat rotary packed bed stable back (about two minutes), about 70 ℃, open baiting valve at the reactor resin and enter steam heater before rotary packed bed, temperature is about about 115 ℃ after using the steam heating of 0.20-0.30MPa, directly enter rotary packed bed in; Progressively tolerance is enlarged to 800m by regulating the air inlet valve
3Standard volume gas.Guarantee that simultaneously rotary packed bed interior vacuum tightness is 20-40kPa, carry out the diffusion of free formaldehyde in the resin under gas-liquid high turbulence in rotary packed bed, strong mixing, the very fast more news of fluid surface layer, like this, resin is through low pressure, the pyroprocessing of moment, removed most free formaldehyde on the one hand smoothly and decomposed the formaldehyde that produces by methylol and methyne ehter bond, resin behind the moment high temperature is deposited stablely on the other hand, simultaneously can significantly reduce dewatering time, reduces consumption.The free formaldehyde content of treated like this urea-formaldehyde resin is reduced less than about 0.11%.Owing to the low pressure of system, most of moisture also is removed simultaneously.
Claims (10)
1, a kind of method that removes free formaldehyde in the urea-formaldehyde resin comprises following processing step: rotary packed bed shell is preheating to 50～80 ℃; Open rotary packed bed and rotating speed is transferred to 200～2500rpm; With the urea-formaldehyde resin after the preheating send into rotary packed bed in; Simultaneously gas (vapour) being carried gas introduces from rotary packed bed inlet mouth; Free formaldehyde wherein is diffused into gas (vapour) and carries in the gas and being taken away by gas, and it is air or nitrogen or water vapour that described gas (vapour) is carried gas.
2 methods that remove urea-formaldehyde resin middle reaches formaldehyde according to claim 1, the gas-liquid volume ratio of itself and urea-formaldehyde resin is 500-1200m when it is characterized in that air or nitrogen as the gas stripping gas body
3Standard volume gas/m
3Liquid, water vapour during as the gas stripping gas body gas-liquid volume ratio of itself and urea-formaldehyde resin be 0.5-100m
3Standard volume gas/m
3
3, the method that removes free formaldehyde in the urea-formaldehyde resin as claimed in claim 1 or 2, the preheating heat temperature that it is characterized in that urea-formaldehyde resin is 50～80 ℃; It is 80-120 ℃ air or nitrogen or water vapour that described gas (vapour) is carried gas; Described gas (vapour) is proposed gas and urea-formaldehyde resin adverse current or cross-flow in rotary packed bed and is contacted.
4, the method that removes free formaldehyde in the urea-formaldehyde resin as claimed in claim 1 or 2, it is characterized in that with the urea-formaldehyde resin temperature be 100-120 ℃, pressure be the water vapour direct heating of 0.25-0.35Mpa introduce after 80-110 ℃ rotary packed bed in, described gas stripping gas body is to be lower than 120 ℃ air or nitrogen, and described gas stripping gas body and urea-formaldehyde resin adverse current or cross-flow in rotary packed bed contact.
5, a kind of described equipment that removes the method for free formaldehyde in the urea-formaldehyde resin of each claim among the claim 1-4 of realizing, comprise one rotary packed bed (15), at this rotary packed bed shell insulation jacket (7) is arranged, toothed gear pump (11) is communicated with the liquid distributor (8) of rotary packed bed (15) by resin well heater (13), the other end of described toothed gear pump (11) links to each other with urea-formaldehyde resin head tank (1), the inlet mouth of rotary packed bed (15) (10) links to each other with gas source, air outlet (4) directly emptying or link to each other with vacuum pump (14).
6,, it is characterized in that described gas source is air compressor or Nitrogen plant according to the equipment that removes urea-formaldehyde resin middle reaches formaldehyde of claim 5.
7, according to the equipment that removes free formaldehyde in the urea-formaldehyde resin of claim 6, it is characterized in that being provided with between air compressor or Nitrogen plant and the inlet mouth gas-heating apparatus (17).
8, according to the equipment that removes free formaldehyde in the urea-formaldehyde resin of claim 5, it is characterized in that described gas source is the water vapour producer.
9, according to the described equipment that removes free formaldehyde in the urea-formaldehyde resin of arbitrary claim among the claim 5-8, it is characterized in that the both sides of filler (23), rotary packed bed (15) inner casing are provided with gas baffle ring (22).
10, according to the equipment that removes free formaldehyde in the urea-formaldehyde resin of claim 9, it is characterized in that the bottom of gas shelves ring has outage.
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|---|---|---|---|
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| CN1821280A (en) | 2006-08-23 |
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