CN105085423B - Technique and relevant device for drying melamine crystal - Google Patents
Technique and relevant device for drying melamine crystal Download PDFInfo
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- CN105085423B CN105085423B CN201510261010.5A CN201510261010A CN105085423B CN 105085423 B CN105085423 B CN 105085423B CN 201510261010 A CN201510261010 A CN 201510261010A CN 105085423 B CN105085423 B CN 105085423B
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- 238000001035 drying Methods 0.000 title claims abstract description 89
- 229920000877 Melamine resin Polymers 0.000 title claims abstract description 83
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000013078 crystal Substances 0.000 title claims abstract description 23
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 86
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 43
- 239000012047 saturated solution Substances 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000000354 decomposition reaction Methods 0.000 claims description 13
- 238000011144 upstream manufacturing Methods 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 11
- 239000000843 powder Substances 0.000 claims description 9
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 7
- 238000000197 pyrolysis Methods 0.000 claims description 6
- 238000012937 correction Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 150000001412 amines Chemical class 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims 1
- 239000000047 product Substances 0.000 description 112
- 239000007787 solid Substances 0.000 description 18
- 230000008569 process Effects 0.000 description 17
- 238000004519 manufacturing process Methods 0.000 description 14
- 239000000243 solution Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 230000015556 catabolic process Effects 0.000 description 10
- 238000006731 degradation reaction Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 10
- 238000001704 evaporation Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 239000012452 mother liquor Substances 0.000 description 7
- 238000000926 separation method Methods 0.000 description 7
- 230000002411 adverse Effects 0.000 description 6
- 230000002776 aggregation Effects 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 238000010276 construction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 4
- 239000001099 ammonium carbonate Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- 238000005829 trimerization reaction Methods 0.000 description 4
- 241001550224 Apha Species 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 3
- 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
- 230000008859 change Effects 0.000 description 3
- 238000004040 coloring Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000005979 thermal decomposition reaction 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
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000006243 chemical reaction 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
- 239000004744 fabric Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 238000012546 transfer 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
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- PRKQVKDSMLBJBJ-UHFFFAOYSA-N ammonium carbonate Chemical class N.N.OC(O)=O PRKQVKDSMLBJBJ-UHFFFAOYSA-N 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- 235000011162 ammonium carbonates Nutrition 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- OHJMTUPIZMNBFR-UHFFFAOYSA-N biuret Chemical compound NC(=O)NC(N)=O OHJMTUPIZMNBFR-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000001727 in vivo Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000010358 mechanical oscillation Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- YOWAEZWWQFSEJD-UHFFFAOYSA-N quinoxalin-2-amine Chemical compound C1=CC=CC2=NC(N)=CN=C21 YOWAEZWWQFSEJD-UHFFFAOYSA-N 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005549 size reduction Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- 230000032258 transport Effects 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
- 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 present invention relates to a kind of techniques for drying out melamine crystals from the saturated solution containing ammonia, the technique includes the drying steps implemented in contact drying device, wherein, it is being higher than 230 DEG C, under the conditions of temperature preferably in the range of from 230 DEG C to 250 DEG C, so that wet melamine to be dried contacts a period of time with the heated wall of drier, described a period of time is in the range of from 1 minute to 30 minute, preferably in the range of from 2 minutes to 15 minute, more preferably in the range of from 5 minutes to 8 minute, and wherein, the air capacity of drier and the weight ratio of melamine to be dried are supplied in the range of from 0.6:1 to 1.2:1, preferably in the range of from 0.7:1 to 0.8:1.
Description
Technical field
The present invention relates to a kind of techniques and relevant device for drying melamine crystal.
The invention belongs to manufacture the technical field of the industrial technology of melamine.
Particularly, the present invention relates to a kind of for drying the improvement technique of the pure melamine crystal from production equipment,
In the production equipment, using the known device of the particular separation technology of solid in suspension liquid environment, particularly rely on
Centrifuge separation is filtered so that the crystal is separated with crystallization mother liquor.
Background technique
Using the pure melamine crystal of these known devices separation in the exit of solid/liquid separation means in the shape of cake
Formula, the cake has the solid consistency of mother liquor, between the solid consistency from 5% to 15% of the mother liquor, preferably from 8% to
12%.
In view of the property of melamine, dry this cake may cause various problems.
It is in fact known that when melamine is dried, if do not accurately control drying process temperature and
Time, then may decompose phenomenon, so that titer reduces and product has coloring.
It is also known that under the conditions of being higher than 220 DEG C of temperature, it may occur however that the signs of degradation of melamine, this drop
It is directly proportional to both temperature and the residence time under the conditions of temperature to solve phenomenon.Therefore, cryogenic conditions long period of operation (
Operated 2-3 hours under the conditions of 160-170 DEG C of temperature) and at high temperature short-term operation (in the 270-290 DEG C of small behaviour of temperature condition
Make 0.5-2 minutes) in can get dry products purity and color identical result.
The melamine titer of market demands is extremely high and is typically in 99.8% to 99.99% close limit
It is interior, and the numerical value of the coloring according to measured by APHA instrument (see regulation ASTM D 1209-69) has to be lower than 20, is preferably lower than
10。
In order to obtain the dry products with these features, the production technology of high-purity melamine used by the producer
Imagine during drying stage use relatively low temperature, this must in any situation can with normally in atmospheric pressure conditions
The drying process of lower implementation is mutually compatible with.Therefore usually less than 200 DEG C of the temperature of use, it is preferably lower than 170 DEG C.
Moreover, another factor for influencing dry products quality is the amount of the microlite wherein contained.For this purpose, due to trimerization
The fragility of cyanamide crystal, so-called indirect hot wall drier are preferably, in the indirect hot wall drier, to pass through heated wall
Transmit heat: the product to be dried contacted with heated wall is heated, and the moisture evaporation for immersing product falls.
Such drier had not only been used as dry device relative to air but also had been used as the flash type dryers of carrier device
For allow air using much less, therefore it is only necessary to same amount of air, the same amount of air must be sent to
On product to be dried, volatile products (in most cases, the water) direction for that will immerse in melamine cake is extraneous
It transports.As also disclosed in the state of the art, product to be dried is carried this avoids air, so that fine powder
Minimum is generated, the fine powder is originated from the melamine destroyed by the collision between fine powder or the collision with drying equipment wall
Amine crystal.
The indirect heat transfer drier of referred to as hot wall drier or also referred to as contact drying device is characterized in that: being deposited
In heated wall that is fixed or rotating, cake to be dried is sent in the heated wall, and they are made in a variety of manners.Three
Most widely used type is so-called going barrel drier in poly cyanamid dry technology.
Such drier has the enough heating surfaces being usually made out of tubes, and the pipe is located in rotor
It is rotated in vivo and integrally with the rotational circle cylinder, heat medium (typically, the vapor of condensation) is sent to the pipe
In.It has been used in the equipment from application Allied Signal/Eurotecnica technology in 1961 such dry
Dry device, the drier operate under the conditions of slightly low pressure and 160 DEG C -170 DEG C of temperature.
A variety of other types of hot wall driers are proposed by professional constructor.In these other types of driers,
May be mentioned to production melamine process used in heat pan dryer.
The common ground of all these driers is low air consumption, as already mentioned, this limitation fine powder
It is formed.However they need the relatively high residence time that solid flows in drying equipment.According to used drier
Type, the residence time of solid can be changed to 3 hours or more maximum values from 0.5 hour minimum value, described solid
Matter of the residence time of body actually by being present in the solid inside drier under constant quasi- weighing apparatus (regime) service condition
The ratio between the flow rate of cake to be dried is measured to limit.Long residence time is for ensuring wet melamine crystals and hot wall
It is required for being kept in contact one section and providing evaporation for melamine crystals and immerse needed for the evaporation heat of water for the time.
Such as previous defined, allow to obtain the dry products of high quality using the air of minimum, this is because by thin
The formation of powder minimizes, and long residence time of the solid in drier adversely affects the quality of dry finished product.
In fact, it should be pointed out that in rotary-type drier, the advance of product is influenced by being promoted and then being fallen again,
As a result product is made to bear lasting shock, this tends to so that crystal crushes, therefore, described tiny to form tiny product
The number that the increase of product is fallen to the residence time and/or again is directly proportional.These Considerations also show: long residence time is inevitable
It is required that reducing drying temperature most possibly, to avoid the signs of degradation that melamine occurs, the signs of degradation is mainly adjoint
Change product colour and because formed degrade byproduct due to may be decreased titer and occur.Low temperature during drying stage can
To be favorable factor, this is because its signs of degradation for having reduced or eliminated melamine and therefore keeping production according to regulation
Product APHA color and titer；However counter productive can may be had by when thermally decomposing molecule by existing in crystallization cake: in fact,
Be dried under cryogenic conditions these molecules not being destroyed during technique presence prevent dry products reach it is desired most
Small melamine titer numerical value, the titer numerical value necessarily are greater than 99.8% as discussed previously.
Aftermentioned situation is actually by crystallizing product and saturated solution point so as to be dried there are ammonia
From Shi Fasheng, this is specific situation in Melamine Production Technology of the present invention.
The element-specific for influencing drying process according to the present invention actually exists ammonia until close to Melamine Production
At the end of technique: as long as there are ammonia in the solution containing ammonia, in addition to because of caused by urea pyrolysis (result formation ammonia) three
Except poly cyanamid generates reaction and other Undec byproducts for generating, this also result in produce from ammonia and carbon dioxide it
Between reaction byproduct.
In this case, together with melamine, in wet cake there are a large amount of ammonium carbonates, bicarbonate and carbonate (with
And urea, biuret, contracting triuret, guanamine, urea groups guanamine, benzo guanamine etc.), if not eliminating this
A little substances, then its titer that can reduce manufactured goods.
In contact drying device, because the molecule of ammonium carbonate, bicarbonate and carbonate can thermally decompose, pass through
Appropriately combined two main operating parameters: temperature and residence time make they can be deteriorated during drying process (and
It is transformed into gaseous ammonia and carbon dioxide).
It should also be noted that low drying temperature inevitable requirement is used for the big exchange surface of heat transfer and therefore needs drying
The size of device is bigger, the residence time that this obviously increases solids in drier, be not reduce melamine degradation rate and
It is the degradation rate for increasing melamine.
Moreover, in order to eliminate in the possibility still humid air containing ammonia in the exit of drier there are tiny product,
Filter element can be envisaged, for example, the sock set made of fabric, the filter element resists the alkaline ring generated due to there are ammonia
Border.
Finally, leaving the humid air containing ammonia of drier after through the filter cell for separating tiny product
It must be sent to washer, at the washer, it is suitably washed with water, to isolate ammonia.There is no washing for ammonia
The solution that the air washed is discharged into atmosphere, and leaves washer is recycled to preparation technology of melamine, and most
The waste water for leaving equipment is contributed to form afterwards.The processing of this waste water is caused to lose organic product and therefore reduces trimerization
The yield of cyanamide production technology.
Other defects of such contact drying device are possible be in the inlet of wet cake mainly the of drier
Crust is formed on hot wall in a part.
Together with due to causing wet plate to have nature viscosity in the presence of mother liquor is saturated with, the block of wet plate to be dried constructs practical
On can cause there is material to retain on the hot surface of drier, to form crust, temperature condition of the crust in heated wall
Under the Normal residence time of product considerably longer than dried of time for being kept on the inner surface of drier.
Therefore, it is necessary to use the specific precautionary measures to prevent or minimize the formation of crust, melamine otherwise will lead to
Amine thermal degradation, because the crust is attached to heated wall and therefore keeps much long in maximum dry next section of temperature strip part
In the time of Normal residence time.In addition to other than sintering phenomenon occurs in the monocrystalline in bigger crystallization group, this thermal degradation is also
Result in the result that melamine has coloring and/or reduces the titer of melamine.
In order to limit these undesirable phenomenons, multiple systems are used in melamine manufacturing equipment, it is such as, dry
The mechanical oscillation of device shell, the period of drier clean, furthermore, if necessary, screening and mill-drying product.
In short, therefore, following item is main problem related with the contact drying device of rotary or disc type is used
Or defect:
Because of sizable storage so that the dead time of product is long；
Consider that the operation temperature of filter cell, the amount of dry air must be excessively not up to close to dew point
The value of value, to prevent filter cell moist due to remaining attached to the product on surface and then block.However, in drying
The formation and pollution of a greater amount of tiny products that air causes must then to separate and remove are excessively used in device；
Because wet product is maintained at pipe (in rotary drier) or because non-on the surface of disk (in pan dryer)
Mew layer and result in crust；These crust are detached from once in a while, to be eventually positioned in manufactured goods, and even if are crusted along them
Access inside drier is broken, they are still resulted in there are crystal grain aggregation, and the crystal grain aggregation is " thin with being defined as
The size of piece "；
The period is needed to clean to remove crust, the crust is gradually biased to heat exchange surface, and (this operation, which needs to produce, to be set
The time of standby shut-down about two days)；
Residence time with about 3 hours proportionally generates tiny product.
The substitution solution of the aforementioned contact formula drier used in some industrial technologies is imagined dry using turbine type
Dry device, in turbo drier, under the mechanism of blade rotor, so that in atmospheric pressure and being done in melamine practice
Dry device inner wall contacts one section of residence time with the heated wall of drier under the conditions of the temperature within the scope of 225 DEG C to 280 DEG C,
The residence time, the blade rotor was centrifugated wet melamine cake preferably within the scope of 15 seconds to 100 seconds,
In, the gas flowing of the air or nitrogen of introducing is for maintaining the turbulent condition for the melamine crystals dried.
The humid air containing ammonia for leaving drier is subjected to being directed to the above-mentioned place of rotary or disc type contact drying device
Reason:
Since the particle and blade of product and dry wall are hit and are mutually hit, and since high revolving speed is (opposite
It is 410g/m) in the rotary drier of 2.6g/m, results in tiny product and increase；
Excessive air is needed to carry out running equipment, it is subsequent to handle the excess air (for 30,000MTPY's
For equipment, for the air of 3, the 500kg/h from rotary drier, air to be processed corresponds to 12,000kg/h),
This needs as a result to lead to bigger investment and operating cost using having larger sized airhandling equipment；
The extremely short residence time, this not allow complete thermal degradation byproduct (for the flat of rotary drier
For equal 2.7 hours, less than 5 minutes, preferably less than 1 minute).As a result, this decomposition is slow in the product packed
Ground continues to occur, and forms ammonia and water, has serious ring so as to cause at the final place to use for opening bag (strong ammonia taste)
Border pollution, and there may be because of product agglomeration caused by forming wet area.
At drier inner air/product co-flow (flow in equicurrent): the humidity containing ammonia is empty
Gas is retained in the inter-particulate spaces for having packed product, as a result occurs ammonia pollution in packaging area, and if cooling
Moisture is discharged in product, as a result forms agglomeration；
Equipment operates under conditions of high revolution and high-temperature (up to 280 DEG C), therefore needs during construction phase
Specific accuracy and the specific maintenance of machine of needs, it is necessary to the maintenance of machine is at least partly implemented by same constructor,
It is higher compared with other types of contact drying device cost, lead to complicated starting and the shutdown procedure of equipment.
Finally, the case where representing the flash type dryers for other viable alternatives of melamine drying process
In, main problem related with their usage and defect are as follows:
(air is also used as carrier to excess air containing ammonia to be processed, and required air capacity is with identical
13 times of air needed for the rotary contact type drier of potential, for 3, the 500kg/h 45 of the equipment of 30,000MTPY,
000kg/h)；
In drier inner air/production co-flow: the humid air containing ammonia is retained in the particle of packaged product
Between in space, ammonia pollution as a result occurs in packaging area, and discharge moisture in the product if cooling, as a result forms knot
Block；
Tiny product is increased due to the shock of product particle and dry wall and product particle are mutually hit；
If directly heating air, possible polluted product using combustion product gases.
Therefore, in the dry field of melamine the common trait of aforementioned all driers of prior art state be using
Air removes vapor, and the vapor formed during evaporating identical water from melamine to be dried.Do not having
In the case where having air, this vapor will holding be trapped in the inter-particulate spaces of product, once as a result melamine from
Drier is opened, then vapor condenses again during melamine cooling stage.
As has already been mentioned above, the basic sides of process according to the invention also reside in: in melamine to be dried
There are ammonia in the sucking mother liquor of wet cake.It needs particularly to handle the humid air for leaving drier there are such case of ammonia, as above
Described, this processing includes:
Such as the humid air containing ammonia is filtered by filter cell, for separating and removing by the air bearing
Tiny product, the filter cell such as sock set made of fabric constitutes, and the filter element is resisted because there are ammonia
And the alkaline environment generated；
Make ammonia and air separation by absorbing (washing) with water and recycle；
Equipment waste water is directly proportional to the water used in washing process, and therefore directly proportional to air capacity；
Ammonia solution is recycled and recycling in processing section；
After drying, it can will wash and cleaned air is discharged into atmosphere or is recycled in drier.
, it will thus be apparent that the sizing for above-mentioned processing of the air capacity used in drier
(sizing) extremely important and for efficiency.
Summary of the invention
The purpose of the present invention is overcoming drawbacks described above, the defect is the feature of the prior art.
In fact, it is wondrous it is found out that, improved drying process allows the contact type dry with non-turbine formula drier
Dry device obtains high quality dry product in the case where the operating condition suitably optimized.
Therefore, the purpose of the present invention is related to a kind of for drying out the work of melamine crystals from the saturated solution containing ammonia
Skill, the technique include the drying stage implemented in contact drying device, wherein so that wet melamine to be dried is in height
A period of time is contacted with the heated wall of drier under conditions of 230 DEG C, the time within the scope of from 1 to 30 minute, and
The weight ratio of the air capacity and melamine to be dried that are wherein supplied in drier is in the range of from 0.6:1 to 1.2:1.
Preferably implement under the conditions of temperature within the scope of from 230 DEG C to 250 DEG C for drying melamine crystal
Technique.This technique is preferably implemented a period of time, described a period of time in the range of from 2 minutes to 15 minute, even
More preferably in the range of from 5 minutes to 8 minute.It preferably, can be in the air capacity for being supplied to drier relative to dry
The weight ratio of dry melamine in the range of from 0.7:1 to 0.8:1 under conditions of implement the technique.
Temperature conditions permit according to the present invention obtains the higher delivery air of temperature in proportion, and therefore, the output is empty
Gas is far from condensation point；This leads to the other advantages operated under conditions of less air capacity, although being far from saturation.Using subtracting
A small amount of air also results in energy relevant to supply air and the size reduction of ventilation equipment needed for making air movement
It saves.
Present invention has surprisingly found that: the drying stage implemented with optimal conditions allows same in contact drying device
The decomposition of the drying of Shi Jinhang melamine and the byproduct that can be thermally decomposed, so that the finished product of high quality is obtained, the contact
Formula drier is as described above neither turbo drier also non-flash type dryers.
It is upstream supplied to be supplied to the air of drier preferably relative to the flowing of melamine to be dried.
Contact drying device is preferably rotary-type drier, wherein at outermost point, circumferential speed from
In the range of 0.2m/s to 2m/s, preferably in the range of from 0.4m/s to 0.8m/s.An end of cylinder into
The wet cake entered is moved due to rotation with the opposed end of desired rate of translation towards the cylinder.
Dry products from drying stage are in the form of flowing powder.In this powder, preferably less than 125 microns
Particle account for 90%, the particle less than 250 microns accounts for 97%, and the powder described in any situation does not have greater than 350 microns
Particle.
Moreover, this dry products meet high quality commercial product specification, such as, for example, by weight of from more than 99.8%
Titer and Alpha (Alpha) color lower than 20.
Process according to the invention may include subsequent finishing stage, wherein hot-air is in from 120 DEG C to 180 DEG C
Under the conditions of temperature in range and the residence time is in the range of from 5 minutes to 300 minute, preferably from 20 minutes to
In the range of 200 minutes, even more preferred in the range of from 40 minutes to 120 minute.
Implement the finishing stage in decomposition/calibration devices appropriate, the decomposition/calibration devices can be and drying
The device that the device of device separation either becomes one with drier.
Process according to the invention has discovered that the optimum range of temperature, residence time and air capacity, the best model
It encloses permission and implements drying process in rotary-type universal contact formula drier, while obtaining following advantage:
Relative to air capacity needed for the drying process implemented in flash type dryers or turbo drier, need
Less air capacity；
Can upstream convey dry air relative to melamine to be dried, and this solution minimize or
Eliminate the wet air containing ammonia in the presence of dry products；
Because the slow-speed of revolution not will lead to crystal block destruction, compared with flash type dryers or turbo drier,
Reduce the generation of tiny product；
Because shorten the residence time, connect with what is operated under the conditions of temperature within the scope of from 100 DEG C to 200 DEG C
Touch drier is compared, and the generation of tiny product is reduced；
Avoid the risk polluted by combustion product gases；
Compared with the temperature of the contact drying device run with traditional mode, operated under the conditions of higher temperature,
Drier used in process according to the invention does not need arrest surface: can be in the item in the region remaining stationary there is no product
The inner contact surface contacted with product is obtained under part, however, allowing to carry out optimal drying to melamine in a short time simultaneously；
Drier does not need period cleaning, and reason is: not actually existing the arrest surface of wet product, stops described
Stay in surface, product tends to be attached on drier and fouling on the dryer, subsequently form be detached from and be ultimately present in
Thin slice in manufactured goods, to be adversely affected to feature.
Therefore, one in the advantage of drying process according to the present invention has with the air capacity used in drying process
Close, as described above, supplying air to drier with following conditions: the flowing relative to melamine to be dried upstream or
With the supply of identical flow direction, preferably adverse current is supplied, and the weight ratio of air and melamine to be dried from
In the range of 0.6:1 to 1.2:1, preferably in the range of from 0.7:1 to 0.8:1.
The air requirements in drying process can be divided as follows:
For air needed for removing water vapour and ammonia；
Excessive diluent air.
The air capacity of supply, which actually must assure that, to be removed due to evaporation contains the ammonium hydroxide in melamine to be dried
The vapor and ammonia of generation, while a part of the air supplied is excess air, the excess air is as permission air
Diluent air needed for temperature and humidity percentage sufficiently deviates dew point.Under conditions of the operation temperature of filter cell, this
Prevent that water from may condense and result remains in melamine suitable for separating and recycling by self-contained tiny of air
On the surface of product.
In the rotary-type contact drying device operated within the temperature range of from 120 DEG C to 170 DEG C, the air capacity of supply with
The weight ratio of product to be dried containing about 10% water is usually 1:1.
Under conditions of this ratio and supply air under the conditions of 160 DEG C to 170 DEG C of temperature, a kind of air is obtained
Output temperature, the nargin (margin) that it is about 40 DEG C relative to dew point that air output temperature, which has,.In fact, in view of filtering
The actual temperature on surface is even lower because of the adverse current cleaning cycle that cold air is implemented, and further reduces this nargin.
Because the amount and size of tiny product are directly proportional to the rate of the air inside drier, the air of supply
Amount is bigger, then the amount of the tiny product carried is bigger.
In a preferred embodiment of the invention, therefore the total amount of air needed for supplying above-mentioned purpose: in dry rank
Section during supply total air in the range of from 20% to 60%, preferably in the range of from 30% to 50%, and
Portion of air in the range of from 30% to 40% is fed into drier even more preferred, and the total sky supplied
Gas in the range of from 40% to 80%, preferably in the range of from 50% to 70%, more preferably from 60% to
Its remainder air in the range of 70% is fed into the pipeline for leaving the air of drier, and the pipeline is preferably tight
The downstream of adjacent drier itself.
It has indeed surprisingly been found that: in order to remove vapor, relative to the total air for being supplied to drier
The air of relatively low amount is just enough: in a preferred embodiment, it is contemplated that the amount of supply air is reduced even morely, this is really
It protects:
Good carrying rate, it is ensured that vapor is completely absent in output products；
By the amount, humidity percentage and final temperature of the air of filtering surface with it is dry by being supplied to whole air
Dry device quantity obtained, humidity percentage are identical with final temperature.
According to this preferred embodiment, therefore usually obtain following result:
Remove the vapor formed due to containing the water in solid to be dried because evaporating；
Air is kept to pass through filter element under the conditions of the humidity percentage and temperature far from dew point,
Following other advantages can be added to the preferred embodiment for the process according to the invention having been described:
In the case where the tiny product only reduces for being formed and being carried, reduced by the amount of the air of drier
70%；
It can be flowed relative to melamine to be dried and upstream convey dry air, and this solution is minimum
Change or eliminate the wet air containing ammonia present in dry products；
Amount by reducing tiny product reduces required filtering surface, in fact, reducing plugging rate and reduction
The relative increase of pressure drop；
The amount of tiny product to be removed reduces in process.
Other purposes of the invention are related to a kind of for implementing drying steps in the drying process of melamine crystals
Equipment, the equipment include contact drying device and one or more filter cells for being located at drier downstream, the filtering
Device element is used to filter humid air at dryer export, which is characterized in that drier imagines a kind of trimerization not to be dried
The structure in surface, place or region that cyanamide can adhere to or be attached.
Equipment according to the present invention preferably imagines the air supply system for upstream supplying air to drier.
The air supply system for upstream supplying air to drier preferably imagines bypath system, wherein the first pipe
Road upstream supplies be supplied directly to drier first of total air relative to the flow direction of melamine cake to be dried
Part, and second pipe at the downstream of drier, in the inlet of filter element, be preferably adjacent to the downstream of filter itself
Place supplies the second part of total air.
The surface, place or the area that do not have wet melamine and can adhere to or be attached used in the process according to the present invention
A kind of thin-slab structure can be envisaged in the drier of the structure in domain, wherein covers heating tube 21, the protection hat by protection crown member 22
Shape part has the form for being adapted ensure that and being promoted and product to be dried then being made to advance.This form for example can be petal
Type, the petal-shaped region that can adhere to or be attached without product, and maximumlly avoid to form crust and crystal block.
Using these solutions, the sclerderm itself after falling off is avoided to crush due to form balky sclerderm and shape
At the glomeration of melamine crystals.
As previously mentioned, process according to the invention may include the subsequent fine implemented in calibration devices appropriate or decomposer
Synchronizing is rapid, wherein under the conditions of hot-air is in the temperature within the scope of from 120 DEG C to 180 DEG C and the residence time is from 5 minutes
To within the scope of 300 minutes, preferably within the scope of from 20 minutes to 200 minute, even more preferred from 40 minutes to 120
In minute range.
Decomposer/finisher can be the device separated with drier or the dress to become one with drier itself
It sets.
Heating can be by any kind of fluid or the power devices with resistance or any other known method are implemented.
It is removed and is steamed by the air stream that can (preferably adverse current) enter in the same direction or countercurrently relative to the direction of advance of product
Vapour.
Particularly, it can be sent to first finishing area by the hot-air that any known method heats, it is heated for removing
The decomposition product of analytical product, it is described to be just present in melamine by pyrolysis products simply by the presence of the ammonia for inhibiting decomposition, so
Hot-air is transported to arid region afterwards, for removing evaporated product.
Decomposition/calibration devices are preferably rotary barrel, and the rotary barrel is equipped with: fin, and the fin is for leading to
Cross fall again (refalling) be stirred, the stream of hot air upstream passes through the cylinder preferably with respect to product,
In, temperature in the range of from 120 DEG C to 180 DEG C, the temperature be suitable for removing still have because decomposing by pyrolysis products
And the ammonia formed.The air for leaving decomposition cylinder is subsequently used as the supply air inside drier and the removal as vapor
Air.
The fin can have fixed or variable inclination angle, for melamine to be better distributed.
Fin allows to hold product in the state mixed with hot-air, therefore ensures that maximum heat exchange, can
Residue existing for energy, which is decomposed by pyrolysis products and removed simultaneously, is formed by ammonia.
Imagining the second decomposition/correction step drying system keeps system to keep only all excellent for drying stage
Gesture, and in addition, allow product to keep a shorter time section at a high temperature of being in drier, to ensure in any situation
It is decomposed completely by pyrolysis products.
Process according to the invention is particularly advantageous, as it ensure that higher-quality drying melamine, limits simultaneously
Investment and production cost.
In fact, the drying time and residence time of product to be dried are greatly shortened, several minutes of the order of magnitude, and
It is not current institute in non-turbine contact drying device and non-flash contact drying device used in production melamine process
The drying time and residence time of a few hours needed.
Moreover, process according to the invention is preferably by the implementation of counter-flow air stream, allow to obtain from the point of view of environmental point of view
Other advantages eliminate the ammonia residual in the melamine for the drying for leaving drier and also assure heated analytical product
It decomposes completely.
Detailed description of the invention
Under the premise of not limiting the range of application solution claimed, two are listed in fig. 1 and 2
Kind is adapted for carrying out the construction of drying process according to the present invention, and in Fig. 3 into Fig. 5, it shows according to state of the art (figure
And (the rotary drier of Fig. 4 to Fig. 5) embodiment of the invention 3).
Fig. 1 is the schematic diagram of process according to the invention in one embodiment, and the embodiment, which also contemplates, to be separated
Correction step in calibration devices/decomposer and the air bypass system in supply.
Fig. 2 is the schematic diagram of process according to the invention in one embodiment, and the embodiment, which contemplates, to be supplied
When air bypass system, without imagine separation calibration devices/decomposer in correction step.
Fig. 3 is the schematic diagram according to the rotary drier of prior art state.
Fig. 4 and Fig. 5 is the schematic diagram of the different embodiments of rotary drier according to the present invention.
Specific embodiment
Referring to Fig.1, in fact, with vapor or with conduction oil or other suitable for this purpose and the device that is supplied in (2)
Part heats the drying equipment schematically shown with (1).
Wet melamine cake to be dried is introduced into drying equipment (1) by the supply nozzle of wet cake (3).
It will be supplied by a part for the air being heated in heating element (6) that pipeline (6 °) leave by pipeline (6 ')
It is given to finishing element or decomposer (5), and is supplied to drying equipment (1) from there.
Then cake bears to be dried in drying equipment (1), then passes through the outlet nozzle of drying solid (4) and pipeline
(4 ') are guided towards finishing element or decomposer (5).In finishing element (5), dry product bears residue and is produced by thermal decomposition
Other resolution process of product, and manufactured goods are conveyed by pipeline (11), to be packed and be stored.
The hot humid air for leaving drying equipment (1) is supplied with some amount, is left simultaneously by the outlet nozzle (7) of humid air
And filter cell (8) are transported to by pipeline (7 '), for removing tiny product, the amount of the Hot wet air heating supply is convenient for
Remove the volatile products for all vaporizations being present in the cake for the volatile products for being loaded with evaporation.
The second part of the hot-air heated in heating element (6) is supplied directly to pipeline (7 ') by pipeline (6 "),
And it mixes, arrives at filter cell (8) with the air for leaving drying equipment (1) at pipeline (7 ').
Filter cell (8) separates tiny product (9) with the humid air (10) containing ammonia, to be sent to for removing
The subsequent processing of the ammonia.
Referring to Fig. 2, always with vapor or conduction oil or suitable for this purpose and the other devices that are supplied in (2) come plus
The hot drying equipment schematically shown in (1).The wet cake of melamine to be dried is drawn by the supply nozzle (3) of wet cake
Enter in drying equipment (1).
A part of the air heated in heating element (6) left by pipeline (6 °) is supplied to by pipeline (6 ')
Drying equipment (1).
Then, cake bears drying process in drying equipment (1), and then passes through the outlet nozzle of drying solid (4)
Manufactured goods are sent out to be used to pack and store with pipeline (4 ').
The Hot wet air heating for leaving drying equipment (1) is supplied with some amount, left by the outlet nozzle (7) of humid air and
Filter cell (8) are sent to by pipeline (7 '), for removing tiny product, the amount of the Hot wet air heating supply is convenient for removal
It is present in the volatile products of all vaporizations in the cake for being loaded with the volatile products of evaporation.
The second part of the hot-air heated in heating element (6) is supplied directly to pipeline (7 ') by pipeline (6 "),
And it mixes, arrives at filter cell (8) with the air for leaving drying equipment (1) at pipeline (7 ').
Filter cell (8) separates tiny product (9) with the humid air (10) containing ammonia, to send to for removing institute
State the subsequent processing of ammonia.
Fig. 2 also illustrates schematically the schematic diagram of process according to the invention in one embodiment, and the embodiment is set
Want the bypath system for supplying air and the correction step in the calibration devices/decomposer being incorporated in drying equipment.
Fig. 3 shows the rotary drier (20) according to prior art state, and Fig. 3 imagines in left side cross-sectional A to be had
The solution of multirow heating tube (21), and uniline heating tube (21) are imagined in the B of right side section.
In the drier with this construction, wet melamine can be between heating tube and at pipe itself rear
It keeps for a long time, to form crust, the crust may be occasionally come off, thus may in the case where being formed in high temperature drying
It is slightly the glomeration and/or product of yellow.
Fig. 4 illustrates rotary drier according to the present invention (20), contemplates the solution with uniline heating tube (21)
Certainly scheme covers the heating tube by circular crown part (22), and the circular crown part prevents the production directly contacted with heating tube
Product stagnation.In section A, in left side, crown member is also provided with fin (23), and the fin helps to promote product simultaneously
And product then carries out the slope about drier and the advance of multiple turns.
Fig. 5 shows rotary drier according to the present invention (20), contemplates the solution with multirow heating tube (21)
Certainly scheme, wherein protectiveness circular crown part (22) can be produced according to different constructions.In the left side of section A and
The right side of section B shows two kinds of possible forms just to the purpose of explanation.According to this embodiment, the hat of peculiar form
Shape part facilitates and ensures to be promoted product and product then to carry out the slope about drier and the advance of multiple turns.Add
Space between heat pipe (21) and protectiveness crown member (22) can be filled with Heat Conduction Material.
In the case where Fig. 1 to 2 shows the construction of equipment, obtained between gas and solid with so-called " adverse current " mode
Contact.
The drying process of melamine according to the present invention, which is contemplated that, reduces a possibility that product mixes in a longitudinal direction:
As a result exist around average nominal value (between the solid masses dried as present in drier and the supply flow rate of cake
Ratio indicates) residence time destribution that is rather narrow；From the point of view of fluid dynamic viewpoint, obtain extremely similar with plug flow
Pattern of flow, which is characterized in that any part for leaving the drying solid of drier remains in drier inside one and connects very much
The time of nearly above-mentioned nominal value；In other words, product does not stagnate inside drier, to eliminate product over-exposure
Negative results under the conditions of used temperature, and the content of volatile products is more than the also undried product of desired value
System can not even be left.
Due to during drying in drier there is no the residence time of resident wall and product compared with, will not be because of trimerization
Cyanamide crystal is sintered and forms crust or large-sized aggregation.
The drying process of melamine according to the present invention also allows using the wet of the tiny product containing any percentage
Cake to form crust or aggregation without meaning.
Particularly, can be higher than usually in the curing technology in contact-type drier just frequently with the temperature condition of temperature
Lower implementation process according to the invention, the advantage is that significantly increase heat exchange and it is that may be present by thermal decomposition product (such as,
Aminoquinoxaline, bicarbonate and carbonate) destructive dynamics may subtract if do not destroyed by thermal decomposition product
The purity of small manufactured goods.
Due to the relatively slow fact of modified power of melamine under the conditions of being lower than 300 DEG C of temperature,
Under conditions of using the residence time characterized by the technique according to the present invention implemented in the drier for meeting above-mentioned requirements, very
To in the case where the maximum temperature of benefit is claimed, the degradation effect of dry products will not be generated.
Example 1
The wet cake of 3,000kg is collected from solid/liquid/gas separator, the solid/liquid separator is located in the downstream of crystallizer
And the upstream end of traditional rotary drum dryer in the equipment for producing melamine.
In the solution in the mother liquor for accounting for 1.5% immersion cake relative to gross mass, this cake contains to be accounted for by weight
9.38% mother liquor and ammonia content.Wet cake is supplied to the drier of that graphic type in the section A of Fig. 5, it is described
Drier is rotated using petal-like structures and upstream supplies hot-air.The air capacity of supply is equal to 350kg/h.
Therefore, the flow rate of cake is 375kg/h, the temperature of wall is 250 DEG C and at ambient pressure conditions, drier connects
Reforwarding turns about 8 hours.
Heating is implemented by the conduction oil to go in ring in the pipe of rotary drier.
The residence time for estimating the product dried is about 4 minutes.Do not change operating parameter during whole service.
If providing constant average mass values, wherein the variation between a sample and another sample is ignored not
Meter then collected the sample of dry products every about 2 hours, and the variation is in analytical error boundary.In a) arranging for table 1
In show value characterized by product quality and used operating condition, and described value shows applied back tender
The applicability of skill.
The table shows the qualitative amount of correspondence of the melamine produced in industrial equipment in b) column, by the work
The wet cake of industry equipment acquisition a batch 3,000kg.The industrial equipment for collecting wet cake sample is equipped with traditional going barrel drier, described
Going barrel drier operates under conditions of atmospheric pressure and wall temperature are 170 DEG C.
In the b of table 1) column shown in value be in industrial equipment every 8 hours implementation the average value normally sampled, and
And its time range for covering about 72 hours, including collecting the time spent by the sample for 3,000kg of test.
Table 1
The melamine of drying in two kinds of different dry samples and the average characteristics of operating condition.
A) it is classified as drier according to the present invention
B) it is classified as traditional going barrel drier
| a | b | |
| The humidity (w%) of cake | 9.38 | 9.5 (average 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 |
| Melamine titer (w%) | 99.94 | 99.9 (average values) |
| Density (g/cm3) | 0.82 | 0.8 (average value) |
| Particle (%) more than 125 microns | 5.5 | 10-15 |
* titration method: H is used2SO4It neutralizes.
By the data of table 1, it is possible to find: compared with the product of the drying obtained according to the prior art, pass through basis
The product that technique of the invention is dried has higher quality feature.
Claims (20)
1. a kind of for drying out the technique of melamine crystals from the saturated solution containing ammonia, the technique is included in contact
The drying steps implemented in drier, wherein under the conditions of being higher than 230 DEG C of temperature, so that wet melamine to be dried is put
Be set to and contact a period of time with the heated wall of drier, described a period of time in the range of from 1 minute to 30 minute, and its
In, the air capacity of drier is supplied to relative to the weight ratio of melamine to be dried in the range from 0.6:1 to 1.2:1
It is interior.
2. technique according to claim 1, wherein the temperature condition is within the scope of from 230 DEG C to 250 DEG C.
3. technique according to claim 1, wherein described a period of time is in the range of from 2 minutes to 15 minute.
4. technique according to claim 1, wherein described a period of time is in the range of from 5 minutes to 8 minute.
5. technique according to claim 1, wherein the weight ratio is in the range of from 0.7:1 to 0.8:1.
6. technique according to claim 1, wherein the technique includes another subsequent correction step, in device appropriate
Another subsequent fine is implemented with a residence time under the conditions of the middle temperature using hot-air within the scope of from 120 DEG C to 180 DEG C
Synchronizing is rapid, and the residence time is in the range of from 5 minutes to 300 minute.
7. technique according to claim 6, wherein the residence time is in the range of from 20 minutes to 200 minute.
8. technique according to claim 6, wherein the residence time is in the range of from 40 minutes to 120 minute.
9. technique according to any one of claim 1 to 8, wherein the flow inverse relative to melamine to be dried
Supply air to drier to stream.
10. technique according to any one of claim 1 to 8, wherein the contact drying device is preferably rotary-type
Drier, at outermost point, the revolving speed of drier is in the range of from 0.2m/s to 2m/s.
11. technique according to claim 10, wherein the revolving speed of drier is in the range of from 0.4m/s to 0.8m/s.
12. technique according to any one of claim 1 to 8, wherein will be the one of drier by the rotation of drier
The opposed end of the wet melamine to be dried that a end enters towards drier moves, and at the end of drying steps
Dry products in the form of free flowing powder.
13. technique according to claim 12, wherein particle of the size less than 125 microns is greater than in the dry products
90%, particle of the size less than 250 microns is greater than 9%, and there is no the particles that size is greater than 350 microns.
14. a kind of according to claim 1 for drying out melamine crystalline substance from the saturated solution containing ammonia for implementing
The equipment of the technique of body, the equipment provides contact drying device, for the air supply system of the drier and one or
Multiple filter cells, the filter cell is located at the drier downstream, special for filtering the air for leaving drier
Sign is that the drier has a kind of structure, and the structure is equipped with melamine wet cake attachment to be dried or fixed table
Face, place or region.
15. equipment according to claim 14, wherein for the drier air supply system relative to be dried three
The flow direction of poly cyanamid wet cake upstream works.
16. equipment according to claim 14 or 15, wherein gathered around for the air supply system of the drier along countercurrent direction
Have bypath system, wherein first pipe relative to melamine wet cake to be dried flow direction upstream by total air
First part is supplied directly to drier, and second pipe by the second part of total air in drier downstream, in filter elements
The inlet of part supplies.
17. equipment according to claim 14 or 15, wherein the drier includes thin-slab structure, in the thin plate knot
In structure, heating tube is covered by protectiveness crown member, and the shape of the protectiveness crown member, which is adapted ensure that, promotes product to be dried
And product to be dried is then advanced.
18. equipment according to claim 14 or 15, the equipment further includes decomposition/calibration devices, the decomposition/finishing
Device intersects with stream of hot air, and is under the conditions of the temperature between 120 DEG C to 180 DEG C, is suitable for removing by decomposing still
The existing ammonia formed by pyrolysis products.
19. equipment according to claim 18, wherein the decomposition/calibration devices are relative to wet melamine to be dried
The flow direction of amine cake upstream intersects with stream of hot air.
20. equipment according to claim 18, wherein the decomposition/calibration devices are rotary barrels, the rotary barrel
It is equipped with fin, the fin has fixed angle or tool for stirring the product, the fin by falling once again
There is variable incidence.
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| ITMI2014A000926 | 2014-05-21 | ||
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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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