CN101845022B - Equipment for crystallizing melamine and by-product thereof by cooling - Google Patents
Equipment for crystallizing melamine and by-product thereof by cooling Download PDFInfo
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- CN101845022B CN101845022B CN2009100644741A CN200910064474A CN101845022B CN 101845022 B CN101845022 B CN 101845022B CN 2009100644741 A CN2009100644741 A CN 2009100644741A CN 200910064474 A CN200910064474 A CN 200910064474A CN 101845022 B CN101845022 B CN 101845022B
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Abstract
The invention provides equipment for crystallizing melamine and by-product thereof by cooling. The equipment is a coaxial double-layer fluidized bed, wherein the centre of the coaxial double-layer fluidized bed is provided with a riser; the lower part of the riser is provided with a hot gas inlet; a cooling bed is sleeved outside the riser; the bottom of the cooling bed is provided with a fluidization gas inlet and the top of the cooling bed is provided with a fluidization gas outlet; an outlet of the riser is connected with an inlet of a cyclone separator; the upper part of the cyclone separator is provided with a hot gas outlet; a feeding tube I of the cyclone separator extends into the cooling bed; the lower part of the cooling bend is provided with a feeding tube II for a solid cold material; and the feeding tube II is provided with a control valve and connected to the bottom of the riser. By using the equipment, the load is reduced, the amount of circulating water is saved, the cold air circulating fan is saved, the investment in the equipment is reduced and the influence of the urine brought in a crystallizer and stripping of wall accretion of the crystallizer on the running period of the system and the product quality is completely eliminated.
Description
Technical field
The process unit that the present invention often adapts to, the low-pressure urea catalytic reaction is produced melamine relates in particular to a kind of equipment that is used for crystallisation by cooling melamine and accessory substance thereof.
Technical background
Often, the representative technology of low pressure Melamine Production has non-pressure process of German BASF AG and the low-pressure process of Dutch DSM N. V.; And various combined production of melamine technologies of China and various improvement normal pressure circulation technology; The common ground of these technologies all need become melamine accessory substance and melamine solid-state from gaseous state, and from process gas, separates respectively.But different processing methods will influence the manufacturing cost of melamine and the cycle of operation of device largely, and product quality is stable.
The low-pressure process technology of Holland DSM N. V. is: wash with water for cooling together with melamine and accessory substance from the process gas that reactor comes out; Then melamine and accessory substance are centrifugalized from slurries; And then go to dissolve again, sequence of operations unit such as filtration, crystallization, separation, drying; Not only investment is big, and energy consumption is high.And in the process of washing, part melamine generation hydrolysis influences yield.
Non-pressure process of Germany BASF AG and the one-step method joint production process and the various improvement one-step method normal pressure round-robin method technology of China are: the hot gas cooler that passes through a shell and tube from process gas (about 390 ℃ of the temperature) elder generation that reactor comes out; Be cooled to about 320 ℃; Make higher boiling (condensation point) accessory substance become powdery solid by gaseous state; Melamine still is a gaseous state, thisly becomes the accessory substance of powdery and together gets into next operating unit from the catalyst fines that reactor comes out with process gas---the hot gas filtration device.The hot gas cooler of this mode is prone to tie wall and stops up, and the cycle of operation is extremely lacked (about 2 months), and cleaning is difficulty very, needs one to open one fully.Get into melamine crystallizer (device of sublimating) again from the hot gas filtration device gas (about 320 ℃ of temperature) that comes out, the temperature of this crystallizer is controlled at about 210 ℃, and it is the cold air about 140 ℃ that the low-temperature receiver of crystallizer is washed the temperature that tower comes from urine.Because the specific heat of gas is little, the air conditioning quantity that needs is very big, needs independent circulating fan supercharging again, and just the power consumption of circulating cold air blower fan makes ton melamine power consumption increase by 250～350 degree, and round-robin method is about 350 degree, and co-production method is about 250 degree.Simultaneously have a spot of liquid urine unavoidably because urine is washed the cold air that tower comes, slowly on pipeline, tie wall, make the resistance of ducting increasing, system needs periodic cleaning, and coming off of this knot wall thing also influences product quality simultaneously; Especially the knot wall thing of melamine crystallizer inwall comes off frequently, has a strong impact on product quality.Though the low-pressure process of the ability loss-rate of this method Holland DSM N. V. is low, product quality is extremely unstable, and system's cycle of operation is short, invests also relatively large.
Chinese patent " 03159274.0 " has proposed the scheme that a kind of co-production method is produced melamine, and the weak point of this scheme is that investment is bigger, and the cycle of operation is short, and the energy consumption of cold air blower fan is higher.
Summary of the invention
The purpose of this invention is to provide and a kind ofly can reach that system's long-period stable operation, product quality improve and the equipment that is used for crystallisation by cooling melamine and accessory substance thereof stable, that heat is fully recycled.
Adopt following scheme in order to achieve the above object: a kind of equipment that is used for crystallisation by cooling melamine and accessory substance thereof, said equipment are the coaxial-type two-stage fluidized, and coaxial-type two-stage fluidized center is provided with riser; The riser bottom is provided with hot air intake; The riser outside is set with cooling bed, and cooling bed bottom is provided with inlet for fluidization air, and cooling bed top is provided with the fluidized gas outlet; The riser outlet is connected with the import of cyclone separator; Cyclone separator top is provided with heat outlet, the tremie pipe I of cyclone separator extend into cooling bed in, cooling bed bottom is provided with the tremie pipe II of solid cold burden; Tremie pipe II is provided with control valve, and tremie pipe II is connected the riser bottom.
Said fluid bed set inside cooler and solid filler material.
Said coaxial-type two-stage fluidized is used for the crystallisation by cooling of melamine accessory substance, utilizes fluidised wear-resisting filler to make circulating cooling medium, and described wear-resisting filler is ceramic microsphere or quartz sand.
Said coaxial-type two-stage fluidized is used for the crystallisation by cooling of melamine; The epimere of said cooling bed outside is provided with the hot blast heating jacket; The hot blast chuck is provided with hot blast import and hot-blast outlet, and cooling bed middle part is provided with the melamine discharging opening, and the melamine discharging opening connects the pressure conveying worm; The whirlwind dipleg is provided with plural air blowing pressure and takes over, and utilizes solid melamine to make circulating cooling medium.
Said coaxial-type two-stage fluidized or coaxial-type two-stage fluidized group are used for the crystallisation by cooling step of co-production method or round-robin method production melamine.
Employing the present invention have the following advantages: 1, in same equipment with crystallization and cooling separately, crystallization does not take place in the process of cooling and separation of melamine, reach the purpose of long-period stable operation; 2, recovery section heat, the rich part steam that produces, the while has also reduced the cooling load of back liquid urinary system about 70%, has practiced thrift quantity of circulating water; 3, make low-temperature receiver without cold air, make the tolerance that gets into crystallizer reduce 70%, saved the circulating cold air blower fan; The diameter that makes crystallizer and back urine wash tower reduces more than 40%; The finished product whirlwind quantity of crystallizer back reduces simultaneously, and the separation equipment of liquid urinary system reduces, and the flow of liquid urine circulating pump reduces 70%; Make the power consumption of ton melamine reduce by 300～400 degree; Joint production process is about 300 degree, and round-robin method technology is more than 400 degree, and investment of devices reduces; 4, solved thoroughly that liquid urine is brought crystallizer into and crystallizer knot wall thing comes off to the influence of system's cycle of operation and product quality.
Description of drawings
Fig. 1 is used for the structural representation of the coaxial-type two-stage fluidized of melamine accessory substance crystallisation by cooling for the present invention;
Fig. 2 is used for the structural representation of the coaxial-type two-stage fluidized of melamine crystallisation by cooling for the present invention.
The specific embodiment
Embodiment 1
As shown in Figure 1, be used for the coaxial-type two-stage fluidized of melamine accessory substance crystallisation by cooling, its center is provided with riser 1; The riser bottom is provided with hot air intake 7, and riser outside is set with the cooling bed 6 of a set inside cooler 5 and solid filler material, and cooling bed bottom is provided with inlet for fluidization air 4; Cooling bed top is provided with fluidized gas outlet 10, and the riser outlet is connected with the import of cyclone separator 8, and cyclone separator top is provided with heat outlet 9; The tremie pipe I of cyclone separator extend into cooling bed in; Cooling bed bottom is provided with the tremie pipe II 2 of solid cold burden, and tremie pipe II is provided with control valve 3, and tremie pipe II is connected the riser bottom.
The crystallisation by cooling process that said equipment is used for gaseous state melamine accessory substance is to realize like this; Taking out of under the minimum grain size of cooling bed filler and the cooling bed operating gas velocity left nargin between the particle diameter; From the thermal process gas (about 390 ℃ of temperature) that reactor comes out, main component is ammonia, carbon dioxide, melamine and the high condensation point accessory substance (melam, melem, ammelide, ammeline, cyanogen urea acid amides) higher than melamine condensation point; Walk the center riser; Manage the cooling medium wear-resistant ceramic microballoon that gets off (or filler such as glass marble, sand grains, sheet metal) with cooling bed blanking II and mix, cool the temperature on the melamine condensation point temperature (as about 320 ℃) under the high condensation point accessory substance condensation point; Actual temp is relevant with operating pressure; The riser outlet directly connects cyclone separator, and the most of entering of the accessory substance fine powder that separates is cooling bed, and the part fine powder will be taken out of by cooling bed fluidized gas; A part is with the ceramic microsphere circulation of filling, and cooling bed exit gas and whirlwind exit gas merge entering hot gas filtration device.
Said equipment is used for the meaning of the crystallisation by cooling of gaseous state melamine accessory substance, and present hot gas cooler accessory substance is a crystallisation by cooling in pipe, and the disadvantage of crystallisation by cooling is that water environment capacity is little in the pipe, is prone to stop up no self-cleaning function.And use the fluidized bed cooler of dress wearable ceramic ball instead, accessory substance is at the riser intercrystalline, and the frictional cleaning of wearable ceramic ball is arranged, and guaranteed the long-term operation of riser and whirlwind, and resistance is little and stable, makes the power consumption reduction by 15% of compressor.
As shown in Figure 2, the said coaxial-type two-stage fluidized that is used for the melamine crystallisation by cooling, its center is provided with riser 19; The riser bottom is provided with hot air intake 18, and riser outside is set with a set inside cooler 22 and fills the cooling bed 23 of solid melamine material, and cooling bed bottom is provided with inlet for fluidization air 16; Cooling bed middle part is provided with melamine discharging opening 17; Cooling bed top is provided with fluidized gas outlet 15, and the epimere of cooling bed outside is provided with hot blast heating jacket 24, and the hot blast chuck is provided with hot blast import 13 and outlet 14; The riser outlet is connected with the import of cyclone separator 12; The cyclone separator top is provided with heat outlet 11, the tremie pipe I of cyclone separator extend into cooling bed in, cooling bed bottom is provided with the tremie pipe II20 of solid cold burden; Tremie pipe II is provided with control valve 21, and tremie pipe II is connected the riser bottom.
The crystallisation by cooling process that said equipment is used for the gaseous state melamine is achieved in that the thermal process gas (about 320 ℃ of temperature) that comes out from the hot gas filtration device, and main component is ammonia, carbon dioxide, melamine and the low condensation point accessory substance lower than melamine condensation point; Walk the center riser; Mix with the cooling bed cooling medium solid melamine powder that gets off, cool the temperature under the melamine condensation point, the temperature (as 190～210 ℃) on the low condensation point accessory substance condensation point; Actual temp is relevant with operating pressure; The riser outlet directly connects cyclone separator, and the accessory substance fine powder that the separates overwhelming majority gets into cooling bed, and cooling bed top is the fluid bed that band enlarges segregation section; A small amount of thinner melamine is taken out of by cooling bed fluidized gas, and cooling bed exit gas and whirlwind exit gas merge entering finished product cyclone separator.The heat outlet of said coaxial-type two-stage fluidized (whirlwind outlet) temperature must not be lower than the middle part temperature of center riser, preferably is higher than 2～5 ℃ of the middle part temperature of riser, controls through the chuck hot air flow of regulating fluid bed top.
The said fluidisation operating unit equipment that is used for gaseous state melamine crystallisation by cooling, whirlwind dipleg are provided with plural air blowing and take over, and measure the pressure reduction on the whirlwind dipleg through this inflatable mouth, monitor the working condition of dipleg.
Utilize the crystallisation by cooling method of the above embodiments 1, the melamine described in 2 and accessory substance can obtain the combined production of melamine technology that a kind of investment economizes most; The design operation pressure of this device reaction device is decided according to the pressure of extraneous ammonia source of the gas, optional pressure 0.25～0.45MPa (absolute pressure) in joining the alkali device.Flow process is following:
The pressure that cooler is come outside synthetic ammonia evaporimeter or couplet alkali is the pure ammonia elder generation of absolute pressure 0.25～0.45MPa after send into fluid bed as carrier gas after vapor preheater and the preheating of fused salt preheater, and the mass ratio of the quality of the pure ammonia of carrier gas and liquid urine is 1～1.75.Fill the catalyst of preferred 50～70 μ m of average grain diameter in the fluid bed, catalyst can be unformed silicon-aluminium glue, molecular sieve-alumino-silicate composite catalyst, silica gel or gama-alumina.The temperature of fluid bed is 375～405 ℃.Liquid area gets into fluid bed from the branch of liquid urine circulating pump through " low pressure differential atm number binary channels atomizer "; The used atomization gas of the atomizer of charging is a carrier gas branch; Atomization gas and liquid urine were to walk fully independently passage before leaving nozzle; The central tube of liquid urine tape transport adjusting rod; The outer sleeve pipe of central tube is made in atomizing leave with rage, atomization gas about with 110m/s speed and with the angle directive central axis of 30 °～60 ° of central axis angles with the atomizing of liquid urine; The mass ratio 0.3～0.7 of the quality of atomization gas and liquid urine.The chemical equation of melamine is following:
Contain melamine and the high hot gas that coagulates accessory substance from what fluidized-bed reactor came out; Through being filled with the circulation crystallisation by cooling fluid bed of high-abrasive material, be cooled to about 320 ℃, the high accessory substance crystallisation by cooling that coagulates accessory substance comes out; Together get into the hot gas filtration device with process gas, with separation of by-products.
The hot gas filtration device filters condensing some accessory substance of height and catalyst fines get off, and the hot gas filtration device is a kind of equipment with back-blowing device and the insulation of hot blast chuck.The outlet temperature of hot gas filtration device is controlled at about 320 ℃;
The thermal process gas that comes out from the hot gas filtration device gets into the circulation crystallisation by cooling fluid bed of filling solid melamine, the rich part steam that produces, and the heat outlet temperature control of melamine crystallisation by cooling fluid bed is made 180～200 ℃.At this, melamine becomes powdery solid by gas, and the concentrated phase position of circulation crystallisation by cooling fluid bed connects the pressure conveying worm, and the output melamine is to finished product bin, and the process gas of coming out from the crystallisation by cooling fluid bed together gets into the finished product cyclone separator.
Melamine separates in the finished product cyclone separator, discharges through the pressure spiral from its bottom, and gas and a small amount of melamine get into liquid urine scrubbing tower.
The gas that comes out from the finished product cyclone separator washs through the cooling of liquid urine scrubbing tower; The one, low completely condensing some product of unreacted and unsegregated melamine fine powder are reclaimed; Get into reactor in company with liquid urine; The 2nd, 180～200 ℃ gas temperature is reduced to 130～145 ℃, after the foam removal of column cyclone separator, all send into couplet alkali device and absorb with mother liquor as tail gas.
Wherein said circulation crystallisation by cooling fluid bed is the coaxial-type two-stage fluidized, perhaps the circulation crystallisation by cooling fluid bed of block form.
Claims (5)
1. equipment that is used for crystallisation by cooling melamine and accessory substance thereof, it is characterized in that: said equipment is the coaxial-type two-stage fluidized, coaxial-type two-stage fluidized center is provided with riser; The riser bottom is provided with hot air intake, and the riser outside is set with cooling bed, and cooling bed bottom is provided with inlet for fluidization air; Cooling bed top is provided with the fluidized gas outlet, and the riser outlet is connected with the import of cyclone separator, and cyclone separator top is provided with heat outlet; The tremie pipe I of cyclone separator extend into cooling bed in; Cooling bed bottom is provided with the tremie pipe II of solid cold burden, and tremie pipe II is provided with control valve, and tremie pipe II is connected the riser bottom.
2. the equipment that is used for crystallisation by cooling melamine and accessory substance thereof according to claim 1 is characterized in that: said fluid bed set inside cooler and solid filler material.
3. the purposes that is used for the equipment of crystallisation by cooling melamine and accessory substance thereof according to claim 2; It is characterized in that: said coaxial-type two-stage fluidized is used for the crystallisation by cooling of melamine accessory substance; Utilize fluidised wear-resisting filler to make circulating cooling medium, described wear-resisting filler is ceramic microsphere or quartz sand.
4. the purposes that is used for the equipment of crystallisation by cooling melamine and accessory substance thereof according to claim 2; It is characterized in that: said coaxial-type two-stage fluidized is used for the crystallisation by cooling of melamine; The epimere of said cooling bed outside is provided with the hot blast heating jacket; The hot blast chuck is provided with hot blast import and hot-blast outlet, and cooling bed middle part is provided with the melamine discharging opening, and the melamine discharging opening connects the pressure conveying worm; The whirlwind dipleg is provided with plural air blowing pressure and takes over, and utilizes solid melamine to make circulating cooling medium.
5. according to claim 3 or the 4 described purposes that are used for the equipment of crystallisation by cooling melamine and accessory substance thereof, it is characterized in that: said coaxial-type two-stage fluidized or coaxial-type two-stage fluidized group are used for the crystallisation by cooling step of co-production method or round-robin method production melamine.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100644741A CN101845022B (en) | 2009-03-25 | 2009-03-25 | Equipment for crystallizing melamine and by-product thereof by cooling |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100644741A CN101845022B (en) | 2009-03-25 | 2009-03-25 | Equipment for crystallizing melamine and by-product thereof by cooling |
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| CN101845022A CN101845022A (en) | 2010-09-29 |
| CN101845022B true CN101845022B (en) | 2012-07-18 |
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Families Citing this family (7)
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| CN102603661B (en) * | 2012-03-12 | 2014-10-22 | 李靖铭 | Process of using medium-pressure gas-phase quenching method to produce melamine |
| CN102908802A (en) * | 2012-11-07 | 2013-02-06 | 袁哲 | Novel melamine dry catcher |
| CN105503758B (en) * | 2016-01-18 | 2019-05-14 | 尹明大 | A kind of Melamine Production system and technique |
| CN106083752B (en) * | 2016-06-12 | 2020-04-21 | 山东省舜天化工集团有限公司 | Hot gas cooler cleaning device based on melamine production |
| CN108721935B (en) * | 2017-04-14 | 2021-02-09 | 上海泰禾国际贸易有限公司 | Trapping device and process for production of o-chlorobenzonitrile |
| CN109529397A (en) * | 2018-12-28 | 2019-03-29 | 四川金象赛瑞化工股份有限公司 | One kind is sublimated crystallizer and method for crystallising |
| CN111397396A (en) * | 2020-03-19 | 2020-07-10 | 中国成达工程有限公司 | Powder material cooling system and cooling process thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2229829Y (en) * | 1995-06-14 | 1996-06-26 | 蒋大洲 | Equipment for crystallisation of melamine |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2229829Y (en) * | 1995-06-14 | 1996-06-26 | 蒋大洲 | Equipment for crystallisation of melamine |
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