CN105085423A - Technology for drying melamine crystals and associated devices - Google Patents
Technology for drying melamine crystals and associated devices Download PDFInfo
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- CN105085423A CN105085423A CN201510261010.5A CN201510261010A CN105085423A CN 105085423 A CN105085423 A CN 105085423A CN 201510261010 A CN201510261010 A CN 201510261010A CN 105085423 A CN105085423 A CN 105085423A
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- moisture eliminator
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- dried
- drying
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- 238000001035 drying Methods 0.000 title claims abstract description 105
- 229920000877 Melamine resin Polymers 0.000 title claims abstract description 26
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 title claims abstract description 26
- 239000013078 crystal Substances 0.000 title claims abstract description 24
- 238000005516 engineering process Methods 0.000 title abstract description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 84
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 42
- 238000010438 heat treatment Methods 0.000 claims abstract description 25
- 239000012047 saturated solution Substances 0.000 claims abstract description 4
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 64
- 238000000034 method Methods 0.000 claims description 43
- 238000011144 upstream manufacturing Methods 0.000 claims description 13
- 238000001914 filtration Methods 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 10
- 238000000354 decomposition reaction Methods 0.000 claims description 9
- 239000000843 powder Substances 0.000 claims description 9
- 238000012937 correction Methods 0.000 claims description 7
- 230000002411 adverse Effects 0.000 claims description 6
- 238000010276 construction Methods 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims 1
- 239000000047 product Substances 0.000 description 119
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 22
- 239000007787 solid Substances 0.000 description 18
- 241000196324 Embryophyta Species 0.000 description 15
- 230000008569 process Effects 0.000 description 13
- 239000000243 solution Substances 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 10
- 230000015556 catabolic process Effects 0.000 description 9
- 238000006731 degradation reaction Methods 0.000 description 9
- 238000005755 formation reaction Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 7
- 239000012452 mother liquor Substances 0.000 description 7
- 230000008020 evaporation Effects 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- VZXTWGWHSMCWGA-UHFFFAOYSA-N 1,3,5-triazine-2,4-diamine Chemical compound NC1=NC=NC(N)=N1 VZXTWGWHSMCWGA-UHFFFAOYSA-N 0.000 description 2
- 241001550224 Apha Species 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 235000011089 carbon dioxide Nutrition 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 239000003085 diluting agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- GZVHEAJQGPRDLQ-UHFFFAOYSA-N 6-phenyl-1,3,5-triazine-2,4-diamine Chemical compound NC1=NC(N)=NC(C=2C=CC=CC=2)=N1 GZVHEAJQGPRDLQ-UHFFFAOYSA-N 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 244000287680 Garcinia dulcis Species 0.000 description 1
- BVCZEBOGSOYJJT-UHFFFAOYSA-N ammonium carbamate Chemical compound [NH4+].NC([O-])=O BVCZEBOGSOYJJT-UHFFFAOYSA-N 0.000 description 1
- OHJMTUPIZMNBFR-UHFFFAOYSA-N biuret Chemical compound NC(=O)NC(N)=O OHJMTUPIZMNBFR-UHFFFAOYSA-N 0.000 description 1
- KXDHJXZQYSOELW-UHFFFAOYSA-N carbonic acid monoamide Natural products NC(O)=O KXDHJXZQYSOELW-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007791 dehumidification Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000013467 fragmentation Methods 0.000 description 1
- 238000006062 fragmentation reaction Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000001149 thermolysis Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- WNVQBUHCOYRLPA-UHFFFAOYSA-N triuret Chemical compound NC(=O)NC(=O)NC(N)=O WNVQBUHCOYRLPA-UHFFFAOYSA-N 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/40—Nitrogen atoms
- C07D251/54—Three nitrogen atoms
- C07D251/62—Purification of melamine
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Drying Of Solid Materials (AREA)
Abstract
The invention relates to technology for drying out melamine crystals from an ammonia-containing saturated solution. The technology includes a drying step implemented in a contact drier. At a temperature higher than 230 DEG C, preferably ranging from 230 DEG C to 250 DEG C, the contact between wet melamine to be dried and a heating wall of a drier is maintained for a certain period of time. The certain period of time ranges from 1 min to 30 mins, preferably ranges from 2 mins to 15 mins, more preferably ranges from 5 mins to 8 mins. And a weight proportion between air amount which is supplied to the drier and the melamine to be dried ranges from 0.6:1 to 1.2:1, preferably ranges from 0.7:1 to 0.8:1.
Description
Technical field
The present invention relates to a kind of technique for drying melamine crystal and relevant device.
The invention belongs to the technical field of the industrial technology manufacturing trimeric cyanamide.
Especially, the present invention relates to a kind of for the improving technique of drying from the pure melamine crystal of production unit, in described production unit, in suspension liquid environment, use the known device of the particular separation technology of solid, rely on centrifugation or filtration that described crystal is separated with crystallization mother liquor especially.
Background technology
The pure melamine crystal utilizing these known devices to be separated is the form of cake in the exit of solid/liquid separation means, and described cake has the solid consistency of mother liquor, the solid consistency of described mother liquor between 5% to 15%, preferably from 8% to 12%.
Consider the character of trimeric cyanamide, dry this cake may cause various problems.
In fact it is known that when trimeric cyanamide carries out drying, if accurately do not control the temperature and time of drying process, then may there is decomposing phenomenon, make titre reduction and product have painted.
It is also known that higher than under the temperature condition of 220 DEG C, may there is the signs of degradation of trimeric cyanamide, this signs of degradation is directly proportional to temperature and the residence time both under described temperature condition.Therefore, at cold condition prolonged operation (operating 2-3 hour under 160-170 DEG C of temperature condition) and the identical result that at high temperature can obtain drying products purity and color in short period operation (at 270-290 DEG C of temperature condition little operation 0.5-2 minute).
The trimeric cyanamide titre of market demands is extremely high and be typically in the close limit of 99.8% to 99.99%, and the painted numerical value measured by APHA instrument (see regulation ASTMD1209-69) lower than 20, must be preferably lower than 10.
In order to obtain the drying products with these features, the production technology imagination of the high-purity melamine that the producer adopts uses relatively low temperature during drying stage, and this must all can be mutually compatible with the drying operation normally implemented at ambient pressure conditions in any situation.Therefore the temperature adopted is usually less than 200 DEG C, is preferably lower than 170 DEG C.
And another factor affecting drying products quality is the amount of the microlite wherein contained.For this reason, due to the friability of melamine crystals, so-called indirect hot wall moisture eliminator is preferred, in this indirect hot wall moisture eliminator, by heated wall transferring heat: the product to be dried contacted with heated wall is heated, and the moisture evaporation immersing product falls.
Such moisture eliminator had not only been used as dry device relative to air but also had been used as to allow to use for the flash type dryers of carrier device the air of much less, therefore the air of a tittle is only needed, the air of a described tittle must be sent on product to be dried, for the volatile products (in most of the cases, water) immersed in trimeric cyanamide cake is transported towards the external world.As also disclosed in the state of the art, which avoid air and carry product to be dried, thus the generation of fine powder is minimized, the collision between described fine powder is derived from because of fine powder or the melamine crystals destroyed with the collision of drying plant wall.
Be referred to as hot wall moisture eliminator or also referred to as the feature of the indirect heat transfer moisture eliminator of contact drying device: there is heated wall that is fixing or that rotate, cake to be dried is sent in described heated wall, and they are made in a variety of manners.In trimeric cyanamide dry technology, the most widely used type is so-called going barrel moisture eliminator.
Such moisture eliminator has the enough heating surface be usually made out of tubes, described pipe to be positioned in rotational circle cylindrical shell and with the integral rotation of described rotational circle cylindrical shell, heating medium (typically, the water vapour of condensation) is sent in described pipe.In the equipment from application AlliedSignal/Eurotecnica technology in 1961, employ such moisture eliminator, described moisture eliminator operates under the temperature condition of low pressure slightly and 160 DEG C-170 DEG C.
The hot wall moisture eliminator of other type multiple is proposed by professional constructor.In the moisture eliminator of these other types, may be mentioned to and produce the heating pan dryer used in trimeric cyanamide process.
The common ground of all these moisture eliminators is low air consumption, as already mentioned, and the formation of this restriction fine powder.But their relatively high residence time of needing solid to flow in drying plant.According to the type of adopted moisture eliminator, the maximum value that residence time of solid can to change over from the minimum value of 0.5 hour 3 hours or more hour, in fact residence time of described solid is limited by the ratio be present between the quality of the solid of moisture eliminator inside and the flow rate of cake to be dried under weighing (regime) operational conditions in constant standard.It is required that long residence time keeps in touch one section for melamine crystals provides the time of evaporating and immersing needed for evaporation of water heat for the melamine crystals guaranteeing to wet and hot wall.
As previous defined, use the air of minimum to allow to obtain high-quality drying products, this is because the formation of fine powder is reduced to minimum, and the quality of the long residence time of solid in moisture eliminator to dry finished product causes negative impact.In fact, it should be noted that, in rotary-type moisture eliminator, by promoting and falling to affecting the advance of product more subsequently, result makes product bear lasting shock, and this is tending towards crystal is pulverized, thus forms tiny product, therefore, increase and the residence time of described tiny product and/or the number of times that falls again are directly proportional.These Considerations also show: long residence time inevitable requirement reduces drying temperature most possibly, to avoid the signs of degradation that trimeric cyanamide occurs, described signs of degradation mainly may reduce titre along with change product colour and because forming degraded byproduct and occur.Low temperature during drying stage can be favorable factor, this is because it reduces or eliminates the signs of degradation of trimeric cyanamide and therefore keep the product A PHA color according to regulation and titre; But exist in crystallization cake and can decomposes divide the period of the day from 11 p.m. to 1 a.m to have counter productive: in fact, the minimum trimeric cyanamide titre numerical value that the existence of these molecules not destroyed during carrying out drying process under cryogenic prevents drying products from reaching desired, described titre numerical value is as discussed previously must higher than 99.8%.
Occur when in fact aftermentioned situation makes product to be dried be separated with saturated solution when there is ammonia by crystallization, this is specific situation in the Melamine Production Technology that the present invention relates to.
Impact is actually according to the element-specific of drying process of the present invention exists ammonia until close at the end of preparation technology of melamine: as long as there is ammonia in containing the solution of ammonia, then except the trimeric cyanamide formation reaction that causes because of urea pyrolysis (result formation ammonia) and except other the Undec byproduct produced, this also causes the byproduct creating the reaction be derived between ammonia and carbonic acid gas.
In this case, together with trimeric cyanamide, a large amount of volatile salt, supercarbonate and carbonate (and urea, biuret, contracting triuret, guanamine, urea groups guanamine, benzo guanamine etc.) is there is in wet cake, if do not eliminate these materials, then it can reduce the titre of finished product.
In contact drying device, because the molecule of volatile salt, supercarbonate and carbonate can thermolysis, so by appropriately combined two main operating parameters: temperature and the residence time make them can be destroyed during drying process (and being transformed into gaseous ammonia and carbonic acid gas).
It is also important to note that, low drying temperature inevitable requirement is for the large exchange surface of conducting heat and therefore need the size of moisture eliminator larger, this obviously increases the residence time of solid in moisture eliminator, be not reduce trimeric cyanamide degradation rate but increase the degradation rate of trimeric cyanamide.
Such as, and there is tiny product in order to eliminate in may still containing in the wet air of ammonia of the exit of moisture eliminator, can imagine filtering element, the sock cover be made up of fabric, described filtering element resists the alkaline environment produced because there is ammonia.
Finally, the wet air containing ammonia leaving moisture eliminator must be sent to washer after by the filter element for separating of tiny product, at described washer place, suitably washs it with water, to isolate ammonia.Do not have the washed air of ammonia to be discharged in air, and the solution leaving washer is recycled to preparation technology of melamine, and finally contributes to the waste water forming the equipment of leaving.Cause losing organic product and output because this reducing preparation technology of melamine to the process of this waste water.
Other defect of such contact drying device possible hot wall in the first part of the ingress of wet cake mainly at moisture eliminator form crust.
There is mother liquor together with owing to existing to soak into and cause wet plate to have nature viscosity, in fact the block structure of wet plate to be dried can cause has material to retain on the hot surface of moisture eliminator, thus forming crust, the time that described crust keeps under the temperature condition of heated wall on the internal surface of moisture eliminator is longer than the Normal residence time of dry product far away.
Therefore, the specific precautionary measures must be adopted to prevent or to minimize the formation of crust, otherwise trimeric cyanamide thermal destruction can be caused, because described crust is attached to heated wall and therefore remain in the time that maximum dry next section of temperature condition is longer than Normal residence time far away.Except the monocrystalline in larger crystallization group occurs except sintering phenomenon, this thermal destruction also results in trimeric cyanamide to be had painted and/or reduces the result of titre of trimeric cyanamide.
In order to limit these less desirable phenomenons, in trimeric cyanamide producing apparatus, have employed multiple systems, such as, the mechanical vibration of dryer shell, the cycle cleaning of moisture eliminator, moreover, if necessary, screening and mill-drying product.
In brief, therefore, following item is the subject matter relevant with using contact drying device that is rotary or disc type or defect:
The sizable storage of-Yin makes the dead time of product long;
-consider the service temperature of filter element, the amount of dry air must be excessive can not reach the value close to dew point value, thus prevent filter element moist and then block because remaining attached to the product on surface.But excessive use air causes and must be separated subsequently and the formation of the more substantial tiny product removed and pollution in moisture eliminator;
-Yin wet product remain on pipe (in spin drier) or because of coil (in pan dryer) surface on non-new layer and cause formed crust; These crust depart from once in a while, thus are finally arranged in finished product, even and if crust is positioned at the path fragmentation of moisture eliminator inside along them, and they still cause there is crystal grain and assemble, and described crystal grain gathering has the size being defined as " thin slice ";
-need the cycle clean to remove crust, described crust is partial to heat exchange surface (this manipulation require production unit shut-down time of about two days) gradually;
-produce tiny product pro rata with residence time of about 3 hours.
The alternative solution imagination of the aforementioned contact formula moisture eliminator used in some industrial technologies uses turbo drier, in turbo drier, under the mechanical effect of blade rotor, during trimeric cyanamide is put into practice barometric point and moisture eliminator inwall be in 225 DEG C to the temperature condition within the scope of 280 DEG C under contact one period of residence time with the heated wall of moisture eliminator, the described residence time preferably at 15 seconds within the scope of 100 seconds, described blade rotor is to the centrifugation of wet trimeric cyanamide cake, wherein, the air introduced or the gas flow of nitrogen are for maintaining the turbulent state of the melamine crystals of drying.
Leave the above-mentioned process standing the contact drying device for rotary or disc type containing the wet air of ammonia of moisture eliminator:
-clash into and mutually clash into due to the particle of product and blade and dry wall, and due to high rotating speed (be 410g/m relative to the spin drier of 2.6g/m), result in tiny product increases;
-need excessive air to carry out operational outfit, follow-uply must process described excess air (for 30, the equipment of 000MTPY, for from 3 of spin drier, the air of 500kg/h, air to be processed corresponds to 12,000kg/h), this needs use to have larger sized air-treating unit, and result causes larger investment and running cost;
-extremely short residence time, this makes not allow complete thermal destruction byproduct (for average 2.7 hours of spin drier, be less than 5 minutes, be preferably less than 1 minute).Result, this decomposition continues lentamente to occur in the product packed, form ammonia and water, thus cause the final utilization place place opening bag (strong ammonia taste) to have serious environmental pollution, and the product caking caused because forming wet area may be there is.
-in the coflow (flowinequicurrent) of moisture eliminator inner air/product: the damp atmosphere containing ammonia is retained in the inter-particulate spaces of wrapped product, ammonia pollution is there is in result in packaging area, and once cooling, discharge moisture in the product, result forms caking;
-equipment operates under the condition of high revolution and high-temperature (up to 280 DEG C); therefore during construction phase, need specific accuracy and the specific maintenance of machine of needs; described maintenance of machine must be implemented at least in part by same constructor; contact drying device cost than other type is higher, causes the complexity of equipment to start and shutdown procedure.
Finally, when representing the flash type dryers of other viable alternatives being used for trimeric cyanamide drying process, the subject matter relevant with their usage and defect as follows:
-(air is also as carrier for the pending excess air containing ammonia, and required air capacity for there is identical potential rotary contact type moisture eliminator needed for 13 times of air, for 3 of the equipment of 30,000MTPY, 500kg/h is 45,000kg/h);
-in moisture eliminator inner air/product coflow: the wet air containing ammonia is retained in the inter-particulate spaces of packaged product, and result, in packaging area, ammonia pollution occurs, and once cooling, discharges moisture in the product, and result forms caking;
The shock of-Yin product particle and dry wall and product particle mutually clash into and add tiny product;
If-use combustion product gases direct heating air, then may polluted product.
Therefore, in the dry field of trimeric cyanamide, the common trait of aforementioned all moisture eliminators of prior art state uses air to remove water vapour, and described water vapour is formed during evaporate identical water from trimeric cyanamide to be dried.When not having air, maintenance is trapped in the inter-particulate spaces of product by this water vapour, and result is once trimeric cyanamide leaves moisture eliminator, then during trimeric cyanamide cooling stages, water vapour condenses again.
As has already been mentioned above, be also according to the basic sides of technique of the present invention: trimeric cyanamide to be dried wet cake suction mother liquor in there is ammonia.This situation that there is ammonia needs to process the wet air leaving moisture eliminator especially, and as mentioned above, this process comprises:
-such as filter the wet air containing ammonia by filter element, for separating of and remove by the tiny product of described air bearing, the sock cover that described filter element is such as made up of fabric is formed, and described filtering element resists the alkaline environment produced because there is ammonia;
-make ammonia and air separation by absorbing (washing) with water and reclaim;
-equipment waste water is directly proportional to the water yield used in washing process, and is therefore directly proportional to air capacity;
-reclaim ammonia solution by recirculation in processing section;
-after drying, can washing and cleaned air venting in air or be recycled in moisture eliminator.
Therefore, it is evident that, the air capacity used in moisture eliminator for above-mentioned process size (sizing) and efficiency extremely important.
Summary of the invention
The object of the invention is to overcome above-mentioned defect, described defect is the feature of prior art.
In fact, found out that wondrous, the contact drying device of the drying process permission non-turbine formula moisture eliminator of improvement obtains the product of high quality drying when the operational condition suitably optimized.
Therefore, object of the present invention relates to a kind of technique for going out melamine crystals from the saturated solution drying containing ammonia, described technique is included in the drying stage implemented in contact drying device, wherein, wet trimeric cyanamide to be dried is made to contact for some time with the heated wall of moisture eliminator under higher than the condition of 230 DEG C, the described time is within the scope of 1 to 30 minute, and the weight ratio of the air capacity be wherein fed in moisture eliminator and trimeric cyanamide to be dried is in the scope from 0.6:1 to 1.2:1.
Preferably can implement the technique being used for drying melamine crystal under from 230 DEG C to the temperature condition within the scope of 250 DEG C.This technique preferably can implement for some time, described for some time from the scope of 2 minutes to 15 minutes, even more preferably from the scope of 5 minutes to 8 minutes.Preferably, this technique can be implemented under the air capacity being fed to moisture eliminator is relative to condition in the scope from 0.7:1 to 0.8:1 of the weight ratio of trimeric cyanamide to be dried.
Temperature condition according to the present invention allows to obtain the delivery air that temperature is higher in proportion, and therefore, described delivery air is away from condensation point; This causes other advantage operated under the condition of less air capacity, although still away from saturated.The air of decrease is used also to cause to air supply and make the size of the ventilation installation needed for air movement reduce relevant energy to save.
The present invention is surprisingly found out that: the drying stage implemented with optimal conditions allow to carry out in contact drying device simultaneously trimeric cyanamide drying and can the decomposition of byproduct of decomposes, thus obtaining high-quality finished product, described contact drying device is as mentioned above neither turbo drier also non-flash type dryers.
Air to be supplied to moisture eliminator preferably supplies upstream relative to the flowing of trimeric cyanamide to be dried.
Contact drying device is rotary-type moisture eliminator preferably, wherein, at outermost some place, circumferential speed in the scope from 0.2m/s to 2m/s, preferably in the scope from 0.4m/s to 0.8m/s.The wet cake entered in an end of cylinder moves with the opposed end of desired rate of translation towards described cylinder because of rotation.
Drying products from drying stage is the form of flowing powder.In this powder, the particle being preferably less than 125 microns accounts for 90%, and the particle being less than 250 microns accounts for 97%, and described in any situation, powder does not all have the particle being greater than 350 microns.
And this drying products meets high quality commerical prod specification, such as, such as, by weight higher than 99.8% titre and lower than 20 alpha (Alpha) color.
Follow-up finishing stage can be comprised according to technique of the present invention, wherein, warm air to be in from the temperature condition in the scope of 120 DEG C to 180 DEG C and the residence time from the scope of 5 minutes to 300 minutes, preferably from the scope of 20 minutes to 200 minutes, even more preferably from the scope of 40 minutes to 120 minutes.
In suitable decomposition/calibration devices, implement described finishing stage, described decomposition/calibration devices can be the device be separated with moisture eliminator or the device become one with moisture eliminator.
Technique according to the present invention has had been found that the optimum range of temperature, the residence time and air capacity, and described optimum range allows to implement drying process in rotary-type universal contact formula moisture eliminator, obtains following advantage simultaneously:
-relative to the air capacity needed for the drying process implemented in flash type dryers or turbo drier, need less air capacity;
-dry air can be carried upstream relative to trimeric cyanamide to be dried, and this solution to minimize or eliminates in drying products existing wet containing ammonia air;
-because the slow speed of revolution can not cause crystal block to be destroyed, so compared with flash type dryers or turbo drier, decrease the generation of tiny product;
-because shorten the residence time, so compared with the contact drying device operated under from 100 DEG C to the temperature condition within the scope of 200 DEG C, decrease the generation of tiny product;
-avoid the risk polluted by combustion product gases;
-compared with the temperature of the contact drying device run with traditional mode, operate under higher temperature condition, the moisture eliminator used in the process according to the present invention does not need arrest surface: can obtain the inner contact surface contacted with product under there is not product to keep the condition in static region, but, allow to carry out optimum drying to trimeric cyanamide at short notice simultaneously;
-moisture eliminator does not need the cycle to clean, reason is: the arrest surface that in fact there is not wet product, in described arrest surface, product to be tending towards being attached on moisture eliminator and fouling on the dryer, formed subsequently and depart from and the thin slice be finally present in finished product, thus negative impact is caused to feature.
Therefore, relevant with the air capacity used in drying process according in the advantage of drying process of the present invention, as mentioned above, moisture eliminator is supplied air to: supply upstream or with identical flow direction relative to the flowing of trimeric cyanamide to be dried with following condition, preferably adverse current supply, and the weight ratio of air and trimeric cyanamide to be dried is in the scope from 0.6:1 to 1.2:1, preferably in the scope from 0.7:1 to 0.8:1.
The air requirements in drying process can be divided as follows:
-for removing the air needed for water vapor and ammonia;
-excessive diluent air.
In fact the air capacity of supply must be guaranteed to remove the water vapour because evaporation produces containing the ammoniacal liquor in trimeric cyanamide to be dried and ammonia, a part for the air simultaneously supplied is excess air, and described excess air fully departs from diluent air needed for dew point as allowing the temperature and humidity per-cent of air.Under the condition of the service temperature of filter element, this anti-sealing may condense and result makes trimeric cyanamide remain in is suitable for being separated and reclaims by the surface of the self-contained tiny product of air.
In the rotary-type contact drying device operated in the temperature range of 120 DEG C to 170 DEG C, the air capacity of supply is generally 1:1 with the weight ratio of product to be dried of the water containing about 10%.
Under the temperature condition of 160 DEG C to 170 DEG C under air fed condition, obtain a kind of air output temperature at this ratio, it is the nargin (margin) of about 40 DEG C that air output temperature has relative to dew point.In fact, consider the adverse current cleaning cycle that the actual temperature of filtering surface is implemented because of freezing air and even lower, further reduce this nargin.
Because the amount of tiny product and size are directly proportional to the speed of the air of moisture eliminator inside, so the air capacity of supply is larger, then the amount of the tiny product carried is larger.
In a preferred embodiment of the invention, therefore the total amount of the air of supply needed for above-mentioned purpose: the total air supplied during drying stage from the scope of 20% to 60%, preferably from the scope of 30% to 50%, and even more preferably being fed in moisture eliminator from the portion of air in the scope of 30% to 40%, and total air of supply from the scope of 40% to 80%, preferably from the scope of 50% to 70%, more preferably being fed in the pipeline of the air leaving moisture eliminator from its remainder air in the scope of 60% to 70%, described pipeline is preferably close to the downstream of moisture eliminator self.
In fact, it has surprisingly been found that: in order to remove water vapour, just enough relative to the air of relatively low amount of the total air being supplied to moisture eliminator: in a preferred embodiment, therefore imagine air fed amount and reduce even more, this guarantees:
-good carry speed, guarantee to there is not water vapour completely in output products;
-by the amount of the air of filtering surface, humidity percentage and outlet temperature with by whole air being supplied to quantity that moisture eliminator obtains, humidity percentage is identical with outlet temperature.
According to this preferred embodiment, therefore usually obtain following result:
-remove the water vapour formed because evaporation contains the water in solid to be dried;
-keep air by filtering element under away from the humidity percentage of dew point and temperature condition,
Other advantage below can adding to the preferred embodiment according to technique of the present invention described:
-when formed and the tiny product carried reduces only, reduce 70% by the amount of the air of moisture eliminator;
-dry air can be carried upstream relative to trimeric cyanamide to be dried flowing, and this solution minimizes or eliminates exist in drying products wet containing ammonia air;
-pass through the filtering surface needed for amount reduction reducing tiny product, in fact, reduce plugging rate and reduce the relative increase of pressure drop;
The amount of-tiny product to be removed in process reduces.
Other object of the present invention relates to a kind of equipment for implementing drying step in the drying process of melamine crystals, described equipment comprises contact drying device and one or more filter element being positioned at moisture eliminator downstream, described filter element is used for filtering wet air at dryer export place, it is characterized in that, the surface that moisture eliminator imagination is a kind of does not have trimeric cyanamide to be dried to adhere to or to be attached, the structure in place or region.
The air supply system supplying air to moisture eliminator upstream is preferably imagined according to equipment of the present invention.
The air supply system supplying air to moisture eliminator upstream preferably imagines bypath system, wherein, first pipeline supplies the first part being directly supplied to moisture eliminator of total air upstream relative to the flow direction of trimeric cyanamide cake to be dried, and the downstream part of second pipe at moisture eliminator, the ingress at filtering element, be preferably close to the second section that the downstream part of strainer self supplies total air.
The moisture eliminator of the structure in not possessing of using the in the process according to the present invention surface that wet trimeric cyanamide can adhere to or be attached, place or region can imagine a kind of thin-slab construction, wherein, cover heating tube 21 by protection crown member 22, described protection crown member has the form being suitable for guaranteeing to promote and make subsequently product to be dried to advance.This form can be such as petal-shaped, the described petal-shaped region not having product and can adhere to or be attached, and avoids formation crust and crystal block substantially.
Utilize these solutions, avoid forming balky sclerderm because sclerderm self after coming off pulverizes and forming the glomeration of melamine crystals.
As previously mentioned, the follow-up correction step implemented can be included in suitable calibration devices or splitter according to technique of the present invention, wherein, warm air to be in from 120 DEG C to the temperature condition within the scope of 180 DEG C and the residence time from 5 minutes within the scope of 300 minutes, preferably from 20 minutes within the scope of 200 minutes, even more preferably from 40 minutes within the scope of 120 minutes.
Splitter/finisher can be the device be separated with moisture eliminator or the device become one with moisture eliminator self.
Heat by any type fluid or there is the power devices of resistance or other currently known methods any is implemented.
By can relative to the working direction of product in the same way or adverse current (preferably adverse current) the airflow that enters remove steam.
Especially, first the warm air heated by any currently known methods is sent to finishing area, for removing the degradation production of decomposes product, as long as there is the ammonia suppressing to decompose, described decomposes product is just present in trimeric cyanamide, then warm air is transported to arid region, for removing evaporated product.
Decomposition/calibration devices is rotary barrel preferably, described rotary barrel is equipped with: fin, described fin is used for being stirred by fall (refalling) again, described hot blast preferably passes through described cylindrical shell upstream relative to product, wherein, temperature is from the scope of 120 DEG C to 180 DEG C, and described temperature is suitable for removing the ammonia formed because decomposing decomposes product still existed.Leave decompose cylindrical shell air be subsequently used as moisture eliminator inside air supply and be used as water vapour remove air.
Described fin can have fixing or variable inclination angle, distributes better for making trimeric cyanamide.
Product remains in the state mixed with warm air by fin permission, guarantees maximum heat exchange, the residue decomposes Disassembling Products that may exist thus and removes formed ammonia simultaneously.
The dehumidification system keeping system of imagination the second decomposition/correction step keeps having superiority only with regard to drying stage, and in addition, permission product remains in next the shorter time section of high temperature in moisture eliminator, thus in any situation, guarantee that decomposes product decomposes completely.
Favourable especially according to technique of the present invention, because it guarantees higher-quality drying melamine, limit investment and production cost simultaneously.
In fact, greatly shorten time of drying and the residence time of product to be dried, its order of magnitude is several minutes, instead of current time of drying and the residence time producing a few hours required in the non-turbine contact drying device and non-flash contact drying device used in trimeric cyanamide process.
And utilize counter-flow air stream to implement according to optimal process of the present invention, allow to obtain other advantage from environment viewpoint, the ammonia which obviated in the trimeric cyanamide of the drying leaving moisture eliminator remains but also guarantees that the product of decomposes decomposes completely.
Accompanying drawing explanation
Under the prerequisite of scope not limiting applicability solution required for protection; list two kinds to be in fig. 1 and 2 suitable for implementing the structure according to drying process of the present invention; and in Fig. 3 to Fig. 5, show the spin drier according to prior art level (Fig. 3) and the present invention (Fig. 4 to Fig. 5) embodiment.
Fig. 1 is in one embodiment according to the schematic diagram of technique of the present invention, and described embodiment also contemplates in the correction step be separated in calibration devices/splitter and the air bypass system when supplying.
Fig. 2 is the schematic diagram according to technique of the present invention in one embodiment, and described embodiment contemplates the air bypass system when supplying, and does not imagine the correction step in separation calibration devices/splitter.
Fig. 3 is the schematic diagram of the spin drier according to prior art state.
Fig. 4 and Fig. 5 is the schematic diagram of the different embodiments according to spin drier of the present invention.
Embodiment
With reference to Fig. 1, in fact, with water vapour or be suitable for this object with thermal oil or other and the device be supplied in (2) heats the drying plant that use (1) schematically shows.
Wet trimeric cyanamide cake to be dried is incorporated in drying plant (1) by the supplying-nozzle of wet cake (3).
In heating unit (6), be supplied to finishing element or splitter (5) by a part for the air heated by pipeline (6 ') by what left by pipeline (6 °), and be supplied to drying plant (1) from here.
Then cake bears drying treatment in drying plant (1), is guided subsequently by the outlet nozzle (4) of drying solid and pipeline (4 ') towards finishing element or splitter (5).In finishing element (5), dry product bears other disaggregating treatment of residue decomposes product, and by pipeline (11) conveying finished product, to carry out packing and storing.
The hot humid air leaving drying plant (1) supplies with a tittle, left by the outlet nozzle (7) of wet air and be transported to filter element (8) by pipeline (7 '), for removing tiny product, the amount of described Hot wet air heating supply is convenient to remove the volatile products of all vaporizations in the cake being present in the volatile products being loaded with evaporation.
The second section of the warm air of heating is directly supplied to pipeline (7 ') by pipeline (6 ") in the heating unit (6); and in pipeline (7 ') place and the air mixed leaving drying plant (1), arrive at filter element (8).
Filter element (8) makes tiny product (9) be separated with the wet air (10) containing ammonia, to deliver to the subsequent disposal for removing described ammonia.
With reference to Fig. 2, always with water vapour or thermal oil or be suitable for this object and other device be supplied in (2) heats the drying plant schematically shown in use (1).By the supplying-nozzle (3) of wet cake, the wet cake of trimeric cyanamide to be dried is incorporated in drying plant (1).
The part for the air of heating in heating unit (6) left by pipeline (6 °) is supplied to drying plant (1) by pipeline (6 ').
Then, cake bears drying process in drying plant (1), and is sent for packaging by finished product by the outlet nozzle (4) of drying solid and pipeline (4 ') and stored subsequently.
The Hot wet air heating leaving drying plant (1) supplies with a tittle, left by the outlet nozzle (7) of wet air and be sent to filter element (8) by pipeline (7 '), for removing tiny product, the amount of described Hot wet air heating supply is convenient to remove the volatile products of all vaporizations in the cake being present in the volatile products being loaded with evaporation.
The second section of the warm air of heating is directly supplied to pipeline (7 ') by pipeline (6 ") in the heating unit (6); and in pipeline (7 ') place and the air mixed leaving drying plant (1), arrive at filter element (8).
Filter element (8) makes tiny product (9) be separated with the wet air (10) containing ammonia, to deliver to the subsequent disposal for removing described ammonia.
Fig. 2 also illustrate schematically in one embodiment according to the schematic diagram of technique of the present invention, and described embodiment is imagined air fed bypath system and is combined in the correction step in the calibration devices/splitter in drying plant.
Fig. 3 shows the spin drier (20) according to prior art state, and Fig. 3 imagines the solution with multirow heating tube (21) in left side cross-sectional A, and imagines single file heating tube (21) in the B of cross section, right side.
In the moisture eliminator with this structure, wet trimeric cyanamide can keep for a long time between heating tube and at self rear of pipe, thus forming crust, described crust may come off once in a while, thus to be formed in the situation of high temperature drying to be yellow glomeration and/or product slightly.
Fig. 4 illustrates according to spin drier of the present invention (20), it contemplates the solution with single file heating tube (21), cover described heating tube by circular crown part (22), described circular crown part prevents the product directly contacted with heating tube from stagnating.In section A, in left side, crown member also can be provided with fin (23), and described fin contributes to improving product and product carries out slope about moisture eliminator and multiple advance of turning round subsequently.
Fig. 5 shows according to spin drier of the present invention (20), and it contemplates the solution with multirow heating tube (21), wherein, can carry out production protectiveness circular crown part (22) according to different structures.In the left side of section A and on the right side of cross section B, show two kinds of possible form just to the object explained.According to this embodiment, the crown member of peculiar form contributes to and guarantees improving product and product carries out slope about moisture eliminator and multiple advance of turning round subsequently.Space between heating tube (21) and protectiveness crown member (22) can be filled with thermally conductive material.
When Fig. 1 to 2 illustrate when the structure of equipment, obtain the contact between gas and solid with so-called " adverse current " pattern.
The possibility reducing product and mix in a longitudinal direction is also imagined: result exists the residence time destribution be rather narrow around average nominal value (being represented by the ratio between the dry solid masses existed in moisture eliminator and the supply flow rate of cake) according to the drying process of trimeric cyanamide of the present invention; From fluid dynamic viewpoint, obtain the types of flow extremely similar with plug flow, it is characterized in that, any part leaving the drying solid of moisture eliminator all remains in the time of moisture eliminator inside one closely above-mentioned nominal value; In other words, product in the not stagnation of moisture eliminator inside, thus eliminate product be excessively exposed to adopted temperature condition under negative results, and the also undried product that the content of volatile products exceedes expected value even may not leave system.
Due in moisture eliminator, there is not resident wall between dry epoch and the residence time of product comparatively, therefore, can not because melamine crystals sintering and be formed crust or large-sized aggregate.
Also allow the wet cake of the tiny product used containing any per-cent according to the drying process of trimeric cyanamide of the present invention, and formation crust or aggregate can not be meaned.
Especially, can in higher than usual curing technology in contact-type moisture eliminator normal adopt the temperature condition of temperature under implement according to technique of the present invention, its advantage is to significantly increase heat exchange and the decomposes product that may exist (such as, ammonium carbamate, supercarbonate and carbonate) destructive kinetics, if decomposes product does not destroy, then may reduce the purity of finished product.
Because the modified power of trimeric cyanamide is true relatively slowly under lower than the temperature condition of 300 DEG C; therefore; in employing with under the condition of the residence time being feature according to present invention process of implementing in the moisture eliminator meeting above-mentioned requirements; even when the top temperature of claimed benefit, also can not produce the degradation effect of drying products.
Example 1
From solid/liquid/gas separator, collect the wet cake of 3,000kg, described solid/liquid separator is positioned at the upstream end of the downstream of crystallizer and the traditional rotary drum dryer at the equipment for the production of trimeric cyanamide.
Account for relative to total mass 1.5% immersion cake mother liquor in solution in, this cake contains the mother liquor and the ammonia inclusion that account for 9.38% by weight.Wet cake is supplied to the moisture eliminator of that type of diagrammatic in the section A of Fig. 5, described moisture eliminator utilizes petal-like structures rotate and supply warm air upstream.The air capacity of supply equals 350kg/h.
Therefore, the flow rate of cake be 375kg/h, the temperature of wall is 250 DEG C and at ambient pressure conditions, moisture eliminator operates about 8 hours continuously.
Heat and implemented by the thermal oil gone in ring in the pipe of spin drier.
The residence time of the product that estimation is dry is about 4 minutes.Operating parameters is not changed during whole service.
If provide constant average mass values, wherein, the change between a sample and another sample is ignored, then every the sample of about 2 hr collections drying products, described change is in analytical error boundary.The value that to have illustrated with quality product and the operational condition that adopts in a) row of form 1 be feature, and described value indicates the suitability of applied drying process.
Described form has illustrated the qualitative amount of the correspondence of the trimeric cyanamide produced in industrial equipments in b) arranging, and is obtained the wet cake of a collection of 3,000kg by described industrial equipments.The industrial equipments collecting wet cake sample is equipped with traditional going barrel moisture eliminator, and described going barrel moisture eliminator operates under barometric point and wall temperature are the condition of 170 DEG C.
B at form 1) value shown in row is the mean value of normal sampling implemented every 8 hours in industrial equipments, and it covers the time range of about 72 hours, comprise collect for test 3,000kg sample spent by time.
Form 1
The trimeric cyanamide of drying in two kinds of dry samples of difference and the average characteristics of operational condition.
A) be classified as according to moisture eliminator of the present invention
B) traditional going barrel moisture eliminator is classified as
| a | b | |
| The humidity (w%) of cake | 9.38 | 9.5 (mean values) |
| Drying temperature (DEG C) | 250 | 170 |
| The residence time (s) of product | 240 | 9720(2.7hrs) |
| Air capacity | 350kg/h | 3800kg/h |
| APHA color | 5 | 5-10 |
| Trimeric cyanamide titre (w%) | 99.94 | 99.9 (mean values) |
| Density (g/cm 3) | 0.82 | 0.8 (mean value) |
| Particle (%) more than 125 microns | 5.5 | 10-15 |
* titration method: use H
2sO
4neutralization.
By the data of form 1, findable: compared with the product of the drying obtained according to prior art, the product dry by technique according to the present invention has higher qualitative characteristics.
Claims (11)
1. one kind for from the saturated solution containing ammonia dry go out the technique of melamine crystals, described technique is included in the drying step implemented in contact drying device, wherein, higher than under the temperature condition of 230 DEG C, preferably from 230 DEG C under the temperature condition within the scope of 250 DEG C, wet trimeric cyanamide to be dried is placed to and contacts for some time with the heated wall of moisture eliminator, described for some time is from the scope of 1 minute to 30 minutes, preferably from the scope of 2 minutes to 15 minutes, more preferably from the scope of 5 minutes to 8 minutes, and wherein, the air capacity being fed to moisture eliminator relative to the weight ratio of trimeric cyanamide to be dried in the scope from 0.6:1 to 1.2:1, preferably in the scope from 0.7:1 to 0.8:1.
2. technique according to claim 1, described technique comprises another follow-up correction step, in suitable device, utilize warm air to implement another follow-up correction step described with a residence time under from 120 DEG C to the temperature condition within the scope of 180 DEG C, the described residence time is from the scope of 5 minutes to 300 minutes, preferably from the scope of 20 minutes to 200 minutes, more preferably from the scope of 40 minutes to 120 minutes.
3., according to the one or more described technique in aforementioned claim, wherein, supply air to moisture eliminator upstream relative to the flowing of trimeric cyanamide to be dried.
4. according to the one or more described technique in aforementioned claim, wherein, described contact drying device is rotary-type moisture eliminator preferably, at outermost some place, the rotating speed of moisture eliminator in the scope from 0.2m/s to 2m/s, preferably in the scope from 0.4m/s to 0.8m/s.
5. according to the one or more described technique in aforementioned claim, wherein, the wet trimeric cyanamide to be dried entered an end at moisture eliminator by the rotation of moisture eliminator is moved towards the opposed end of moisture eliminator, and the drying products at the end of drying step is the form of free flowing powder, preferably, the particle that in described drying products, size is less than 125 microns is greater than 90%, and the particle that size is less than 250 microns is greater than 9%, and there is not the particle that size is greater than 350 microns.
6. one kind for implementing the equipment going out the technique of melamine crystals for drying according to claim 1, described equipment provides contact drying device (1), for the airing system (6 ') of described moisture eliminator and one or more filter element (9), described filter element is positioned at described moisture eliminator (1) downstream, for filtering the air leaving moisture eliminator (1), it is characterized in that, described moisture eliminator has a kind of structure, and described structure does not have trimeric cyanamide to be dried to wet cake attachment or fixing surface, place or region.
7. equipment according to claim 6, wherein, the airing system (6 ') for described moisture eliminator (1) works upstream relative to the wet flow direction of cake of trimeric cyanamide to be dried.
8. the equipment according to claim 6 and 7, wherein, airing system (6 ') for described moisture eliminator (1) has bypath system along countercurrent direction, wherein, the first part of total air is directly supplied to moisture eliminator (1) relative to the wet flow direction of cake of trimeric cyanamide to be dried by the first pipeline (6 ') upstream, and second pipe (6 ") second section of total air is supplied in moisture eliminator (1) downstream, in the ingress of filter element (8).
9. the equipment according to any one in claim 6 to 8; wherein; described moisture eliminator (1) comprises thin-slab construction; in described thin-slab construction; heating tube (21) is covered by protectiveness crown member (22), and the shape of described protectiveness crown member is suitable for guaranteeing promote product to be dried and product to be dried is advanced subsequently.
10. the equipment according to any one in claim 6 to 9, described equipment also comprises decomposition/calibration devices (5), described decomposition/calibration devices (5) is intersected with hot blast (6 '), preferably relative to the flow direction adverse current of wet trimeric cyanamide cake to be dried, and under being in the temperature condition between 120 DEG C to 180 DEG C, be suitable for removing by decomposing the decomposes product still existed and the ammonia formed.
11. equipment according to claim 10, wherein, described decomposition/calibration devices (5) is rotary barrel, and described rotary barrel is equipped with fin, described fin is used for stirring described product by falling once again, and described fin has fixed angle or has variable angle of inclination.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL1008912C2 (en) * | 1998-04-17 | 1999-10-19 | Dsm Nv | Method of drying melamine. |
| CN101410383A (en) * | 2006-01-30 | 2009-04-15 | 涡龙设备与工艺公司 | A process for drying melamine |
| CN103534545A (en) * | 2011-04-15 | 2014-01-22 | Omya国际股份公司 | Method for drying wet particulate matter, wherein the dried particulate matter is a white mineral having a brightness ry of at least 65% that forms particulate matter through drying in direct superheated steam dryer |
-
2015
- 2015-05-21 CN CN201510261010.5A patent/CN105085423B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL1008912C2 (en) * | 1998-04-17 | 1999-10-19 | Dsm Nv | Method of drying melamine. |
| CN101410383A (en) * | 2006-01-30 | 2009-04-15 | 涡龙设备与工艺公司 | A process for drying melamine |
| CN103534545A (en) * | 2011-04-15 | 2014-01-22 | Omya国际股份公司 | Method for drying wet particulate matter, wherein the dried particulate matter is a white mineral having a brightness ry of at least 65% that forms particulate matter through drying in direct superheated steam dryer |
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