CN105582810B - A kind of preparation method and system of high-purity urea for vehicle solution - Google Patents
A kind of preparation method and system of high-purity urea for vehicle solution Download PDFInfo
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- CN105582810B CN105582810B CN201610005408.7A CN201610005408A CN105582810B CN 105582810 B CN105582810 B CN 105582810B CN 201610005408 A CN201610005408 A CN 201610005408A CN 105582810 B CN105582810 B CN 105582810B
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 239000004202 carbamide Substances 0.000 title claims abstract description 89
- 238000002360 preparation method Methods 0.000 title claims description 8
- 239000007788 liquid Substances 0.000 claims abstract description 41
- 238000002425 crystallisation Methods 0.000 claims abstract description 29
- 230000008025 crystallization Effects 0.000 claims abstract description 23
- 239000000243 solution Substances 0.000 claims abstract description 22
- 239000012528 membrane Substances 0.000 claims abstract description 21
- 239000013078 crystal Substances 0.000 claims abstract description 19
- 239000012047 saturated solution Substances 0.000 claims abstract description 17
- 239000000725 suspension Substances 0.000 claims abstract description 17
- 238000001914 filtration Methods 0.000 claims abstract description 7
- 238000000926 separation method Methods 0.000 claims abstract description 4
- 238000003860 storage Methods 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000000047 product Substances 0.000 claims description 22
- 238000001816 cooling Methods 0.000 claims description 13
- 239000012153 distilled water Substances 0.000 claims description 10
- 238000004821 distillation Methods 0.000 claims description 9
- 239000002994 raw material Substances 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 8
- 238000010304 firing Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 6
- 239000000706 filtrate Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 238000004064 recycling Methods 0.000 claims description 4
- 239000012265 solid product Substances 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 12
- 239000007787 solid Substances 0.000 abstract description 10
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 4
- 239000012452 mother liquor Substances 0.000 abstract description 4
- 239000006104 solid solution Substances 0.000 abstract description 3
- 238000005191 phase separation Methods 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 230000006641 stabilisation Effects 0.000 abstract 1
- 238000011105 stabilization Methods 0.000 abstract 1
- 229910021642 ultra pure water Inorganic materials 0.000 abstract 1
- 239000012498 ultrapure water Substances 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 11
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 238000001764 infiltration Methods 0.000 description 4
- 238000000108 ultra-filtration Methods 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000000909 electrodialysis Methods 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- 239000010413 mother solution Substances 0.000 description 3
- 239000013618 particulate matter Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical group C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010612 desalination reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000003456 ion exchange resin Substances 0.000 description 2
- 229920003303 ion-exchange polymer Polymers 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 238000012271 agricultural production Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000005349 anion exchange Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 235000019628 coolness Nutrition 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000001728 nano-filtration Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000011017 operating method Methods 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 210000002700 urine Anatomy 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2067—Urea
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/01—Engine exhaust gases
- B01D2258/012—Diesel engines and lean burn gasoline engines
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The present invention relates to diesel exhaust gas after-treatment system field, and in particular to a kind of new urea for vehicle production method and system.Using technical grade urea solid or saturated solution, with reference to liquid membrane crystal crystal growth rate is fast and the big advantage of suspension crystallization phase separation area, the urea saturated solution prepared or directly used is passed through the relatively low liquid membrane crystal section of temperature, formation coarse-grain；The higher suspension crystallization section of temperature is passed into again, is purified；Last simple filtration separation, obtains high-purity urea solid, then fills ultra-pure water, obtains urea for vehicle solution.The method of the production urea for vehicle of the present invention intermittently can continuously be designed and operating flexibility is big, and in the absence of mother liquor discharge and pollution problem, product quality stabilization produces facility.
Description
Technical field
The present invention relates to Diesel engine post-processing technology field, and in particular to a kind of new high-purity urea for vehicle production
Method and system.
Background technology
Nitrogen oxides (the NO of emission of diesel enginex) and harm of the particulate matter (PM) to human health and atmospheric environment caused
The concern of height.Countries in the world are devoted to reduce net in the research of this two emissions, including raising fuel qualities, implementation machine
The outside purification technology of change technology and exhaust aftertreatment.China urban have been carried out " state's V " discharge standards mean car
The discharge of tail gas must use more advanced technology.
Catalytic reduction technique (SCR) is to be best suitable for diesel vehicle " state V " discharge solutions, and the use of this technology at present
Reducing agent urea solution carries out SCR to nitrogen oxides, reduces NOxDischarge, so as to meet " state's V " Abgasgesetzs
For PM and NOxLimitation.
But the purity requirement of urea for vehicle is very high, such as the content of the element such as Na, Mg, Al, K, Ca, Fe is not more than
0.5ppm, Cr, Ni, Cu, Zn constituent content are not more than 0.2ppm.Common urea can not meet urea for vehicle and high-cleanness, high wanted
Ask.Obviously, how to purify urea liquid to meet automobile-used technical requirements, be the unavoidable problem of research worker in the industry.
Is being carried out always on the research of urea for vehicle technology at present, mainly there is crystallisation, ion-exchange, micro-filtration/surpass
Filter/counter-infiltration/electrodialysis coupling membrane separation process etc..Wherein, ion exchange needs step less, can pointedly eliminate miscellaneous
Matter, but need regular desalination and change separating medium, complex operation increases extra consumption.Coupling membrane separation process is typically all related to
And more than ten separating steps are, it is necessary to regularly replace film, operate too complicated and extremely easy introducing impurity, scale application difficulty compared with
Greatly.The crystallisation reported at present is divided into evaporative crystallization and crystallisation by cooling, and crystallization technique need not introduce other separating mediums, behaviour
Make comparisons simple, but crystallisation by cooling reaches required purity, it is necessary to which multistage cooling, consumes energy higher；Evaporative crystallization was difficult to control
Saturation degree, temperature is high, and urea is unstable, consumes energy also larger.
Publication No. CN104258730A Chinese patent employs yin, yang secondary ion exchange resin column to urea liquid
Purification process is carried out, although this method can preferably realize the purifying of urea liquid, is periodically required to carry out desalination and more
Separating medium is changed, is expended higher.And Publication No. CN204073982U Chinese patent uses ultrafiltration/counter-infiltration/electrodialysis coupling
Legal, Publication No. CN204111628U Chinese patent uses ultrafiltration/cation and anion exchange coupled method, Publication No.
CN204185305U Chinese patent uses ultrafiltration/nanofiltration/counter-infiltration coupled method, and Publication No. CN203955038U China is specially
Profit uses ion exchange/micro-filtration/ultrafiltration/counter-infiltration/electrodialysis coupled method, and Publication No. CN204097153U Chinese patent is adopted
With two-stage ultrafiltering, though these technologies reach required purity, operating procedures more than ten steps even ten steps is required for, is operated too multiple
It is miscellaneous, it is difficult to control, consumes energy higher, and be easily introduced impurity.Publication No. CN104289106A uses urea one-level crystallisation by cooling, though
Required purity is reached, but higher is required to material purity, the urea production factory of preferable preconditioning technique is only applicable to, is applicable
Scope is narrower, it is impossible to generally applicable.Publication No. CN104557617A is to having deviate from the urea synthesis reaction of ammonia and carbon dioxide
Liquid carries out vacuum flashing crystallization, it is necessary to which extra vacuum equipment, expends larger.Publication No. 102584635A Chinese patent is adopted
Purified, consumed energy higher with the method for three-level crystallisation by cooling.Publication No. 103657498A Chinese patent, devises one kind
Urea liquid device for formulating, can be continuously produced, and product directly dissolving is configured to liquid, but the technology is without purification effect,
It is not suitable for technical grade urea.
The content of the invention
It is an object of the invention to：A kind of method of purification of urea for vehicle solution is provided, this method can utilize technical grade urine
Plain solid or saturated solution, large-scale industrial production, its product quality are stable, with low cost.In addition, in the inventive method not
Need activated carbon or ion exchange resin to be handled, also excluded without harmful mother liquor, it is simple to operate, it is a kind of environment-friendly type, warp
Ji type technology.
Piece-rate system of the present invention, is characterized in utilizing technical grade urea solid or saturated solution, with reference to liquid film
Crystallographic growth rate is fast and the big advantage of suspension crystallization phase separation area, will preparation or the urea saturated solution that directly uses
The relatively low liquid membrane crystal section of temperature is passed through, coarse-grain is formed；The higher suspension crystallization section of temperature is passed into again, is purified；Finally
Simple filtration is separated, and obtains high-purity urea solid, then fills distilled water, obtains urea for vehicle solution.
System used in a kind of preparation method of high-purity urea for vehicle solution of present invention offer, including raw material urea storage tank,
First distillation water storage tank, saturation urea liquid storage tank, feed pump, cooling device, liquid membrane crystal tower, suspension crystallization kettle, stirring are set
Standby, firing equipment, discharging pump, filter plant, filtrate recycling can, after-fractionating water storage tank and urea for vehicle product solution storage tank；
Described raw material urea storage tank and the first distillation water storage tank connection saturation urea liquid storage tank, saturation urea liquid storage tank, charging
Pump, liquid membrane crystal tower, suspension crystallization kettle, discharging pump and filter plant are sequentially connected, and cooling device is carried on liquid membrane crystal tower, are hanged
Floating crystallization kettle is provided with firing equipment and mixing plant, filter plant connection filtrate recycling can and the storage of urea for vehicle product solution
Tank, after-fractionating water storage tank connection urea for vehicle product solution storage tank.
A kind of preparation method of urea for vehicle solution, step is as follows：
Step one：It is molten that urea saturation is prepared with the distilled water in the urea in raw material urea storage tank and the first distillation water storage tank
Liquid, is led to the urea saturated solution in saturation urea liquid storage tank by feed pump at 20-70 DEG C from liquid membrane crystal top of tower
Enter in liquid membrane crystal tower apparatus, flow super cooled sect, it is 30~50 DEG C to keep urea saturated solution and cold section of the temperature difference, is crystallized；
Step 2：The crystallized product that step one is obtained flows through hot arc, keep hot arc and the urea saturated solution temperature difference be 5~
10 DEG C, purification processes are carried out under mixing plant；
Step 3：Product in step 2 is separated from the device afterbody of suspension crystallization kettle by filter plant simple filtration
Afterwards, high-purity urea solid product is obtained；
Step 4：High-purity urea solid product that step 3 is obtained, fills distilled water, obtains urea for vehicle solution product.
Described cold section is liquid membrane crystal section, and temperature is -10~30 DEG C, and described hot arc is suspension crystallization section, and temperature is
25~80 DEG C.
Compared with prior art, the advantage of the invention is that：
(1) present invention is simple to operate, and cold section interconnects with hot arc, and urea for vehicle product is produced therefore, it is possible to continuous, from
And improve production efficiency；
(2) temperature simple of cold section of the present invention and hot arc is controllable, easy to operate；
(3) whole device is closed, it is to avoid influence of the external environment to product quality；
(4) present invention in, the mother liquor isolated, can make industrial urea and agricultural production is used, in the absence of mother liquor discharge and
Pollution problem, is a kind of environment-friendly type, economical technology；
(5) production method of the invention has steady quality, the advantages of production is convenient；
(6) intermittently it can continuously design and operating flexibility is big.
Brief description of the drawings
Fig. 1 is the schematic diagram of preparation method system for use in carrying of the present invention.
Fig. 2 is urea liquid temperature variation curve schematic diagram in a device.
In figure：1 raw material urea storage tank；2 first distillation water storage tanks；3 saturation urea liquid storage tanks；4 feed pumps；5 coolings are set
It is standby；6 liquid membrane crystal towers；7 suspension crystallization kettles；8 mixing plants；9 firing equipments；10 discharging pumps；11 filter plants；12 filtrates are reclaimed
Tank；13 after-fractionating water storage tanks；14 urea for vehicle product solution storage tanks.
Embodiment
Below in conjunction with accompanying drawing and technical scheme, the specific embodiment of the present invention is further illustrated.
Embodiment 1
Urea solid in raw material storage tank is configured to saturated solution with the distilled water in the first distillation water storage tank, prepared
Urea saturated solution (20 DEG C) by feed pump, sequentially enter in liquid membrane crystal tower and suspension crystallization kettle, cooling device maintain
Cold section of temperature is -10 DEG C, and firing equipment maintains hot arc temperature to be 25 DEG C.Product passes through discharging pump from bottom, by filter plant,
The solid of filtering is to obtain high-purity urea solid, the material liquid that the non-crystalline mother solution being filtrated to get can be produced as industrial urea
Recycle.Urea for vehicle solution product is configured to distilled water.
Embodiment 2
Urea solid in raw material storage tank is configured to saturated solution with the distilled water in the first distillation water storage tank, prepared
Urea saturated solution (50 DEG C) by feed pump, sequentially enter in liquid membrane crystal tower and suspension crystallization kettle, cooling device maintain
Cold section of temperature is 10 DEG C, and firing equipment maintains hot arc temperature to be 55 DEG C.Product passes through discharging pump from bottom, by filter plant,
The solid of filtering is to obtain high-purity urea solid, the material liquid that the non-crystalline mother solution being filtrated to get can be produced as industrial urea
Recycle.Urea for vehicle solution product is configured to distilled water.
Embodiment 3
Urea saturated solution (70 DEG C), by feed pump, disposably adds liquid membrane crystal tower by saturation urea liquid storage tank
In suspension crystallization kettle, cooling device maintains cold section of temperature to be 20 DEG C, and firing equipment maintains hot arc temperature to be 80 DEG C.Product is the bottom of from
Discharging pump is passed through in portion, by filter plant, and the solid of filtering is to obtain high-purity urea solid, the non-crystalline mother solution being filtrated to get
The material liquid that can be produced as industrial urea is recycled.Urea for vehicle solution product is configured to distilled water.
Claims (2)
1. the system used in a kind of preparation method of high-purity urea for vehicle solution, it is characterised in that the system includes raw material urea
Storage tank, the first distillation water storage tank, saturation urea liquid storage tank, feed pump, cooling device, liquid membrane crystal tower, suspension crystallization kettle, stir
Mixing equipment, firing equipment, discharging pump, filter plant, filtrate recycling can, after-fractionating water storage tank and the storage of urea for vehicle product solution
Tank；Described raw material urea storage tank and the first distillation water storage tank connection saturation urea liquid storage tank, saturation urea liquid storage tank, enter
Material pump, liquid membrane crystal tower, suspension crystallization kettle, discharging pump and filter plant are sequentially connected, and cooling device is carried on liquid membrane crystal tower,
Suspension crystallization kettle is provided with firing equipment and mixing plant, filter plant connection filtrate recycling can and the storage of urea for vehicle product solution
Tank, after-fractionating water storage tank connection urea for vehicle product solution storage tank.
2. a kind of system with described in claim 1 carries out the preparation method of urea for vehicle solution, it is characterised in that step is such as
Under：
Step one：Urea saturated solution is prepared with the distilled water in the urea in raw material urea storage tank and the first distillation water storage tank,
The urea saturated solution in saturation urea liquid storage tank is passed through liquid by feed pump from liquid membrane crystal top of tower at 20-70 DEG C
In membrane crystallization tower apparatus, super cooled sect is flowed, it is 30~50 DEG C to keep urea saturated solution and cold section of the temperature difference, is crystallized；
Step 2：The crystallized product that step one is obtained flows through hot arc, and it is 5~10 with the urea saturated solution temperature difference to keep hot arc
DEG C, purification processes are carried out under mixing plant；
Step 3：Product in step 2 after the separation of filter plant simple filtration, is obtained from the device afterbody of suspension crystallization kettle
To high-purity urea solid product；
Step 4：High-purity urea solid product that step 3 is obtained, fills distilled water, obtains urea for vehicle solution；
Described cold section is liquid membrane crystal section, and temperature is -10~30 DEG C, and described hot arc is suspension crystallization section, temperature is 25~
80℃。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610005408.7A CN105582810B (en) | 2016-01-06 | 2016-01-06 | A kind of preparation method and system of high-purity urea for vehicle solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610005408.7A CN105582810B (en) | 2016-01-06 | 2016-01-06 | A kind of preparation method and system of high-purity urea for vehicle solution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN105582810A CN105582810A (en) | 2016-05-18 |
| CN105582810B true CN105582810B (en) | 2017-10-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201610005408.7A Active CN105582810B (en) | 2016-01-06 | 2016-01-06 | A kind of preparation method and system of high-purity urea for vehicle solution |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107774183A (en) * | 2016-08-31 | 2018-03-09 | 衡水卡力洁环保科技有限公司 | A kind of urea for vehicle production equipment and process |
| CN112094207A (en) * | 2020-09-30 | 2020-12-18 | 河南弘康环保科技有限公司 | Preparation method of low-formaldehyde automobile urea solution |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101774555A (en) * | 2010-02-02 | 2010-07-14 | 天津大学 | Method for preparing electronic grade phosphoric acid through liquid membrane crystallization |
| CN102198937A (en) * | 2011-04-18 | 2011-09-28 | 天津大学 | Static multistage melting crystallization method for preparing electronic grade phosphoric acid |
| CN102442928A (en) * | 2012-01-09 | 2012-05-09 | 四川泸天化股份有限公司 | Purification method for urea |
| CN102584635A (en) * | 2012-01-09 | 2012-07-18 | 四川泸天化股份有限公司 | Preparation method for urea for vehicle |
| CN104289106A (en) * | 2014-09-23 | 2015-01-21 | 河南弘康环保科技有限公司 | Method for preparing vehicle urea solution |
-
2016
- 2016-01-06 CN CN201610005408.7A patent/CN105582810B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101774555A (en) * | 2010-02-02 | 2010-07-14 | 天津大学 | Method for preparing electronic grade phosphoric acid through liquid membrane crystallization |
| CN102198937A (en) * | 2011-04-18 | 2011-09-28 | 天津大学 | Static multistage melting crystallization method for preparing electronic grade phosphoric acid |
| CN102442928A (en) * | 2012-01-09 | 2012-05-09 | 四川泸天化股份有限公司 | Purification method for urea |
| CN102584635A (en) * | 2012-01-09 | 2012-07-18 | 四川泸天化股份有限公司 | Preparation method for urea for vehicle |
| CN104289106A (en) * | 2014-09-23 | 2015-01-21 | 河南弘康环保科技有限公司 | Method for preparing vehicle urea solution |
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