CN114768294B - Continuous crystallization system of thiourea - Google Patents
Continuous crystallization system of thiourea Download PDFInfo
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- CN114768294B CN114768294B CN202210701236.2A CN202210701236A CN114768294B CN 114768294 B CN114768294 B CN 114768294B CN 202210701236 A CN202210701236 A CN 202210701236A CN 114768294 B CN114768294 B CN 114768294B
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- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 title claims abstract description 254
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Natural products NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 127
- 238000002425 crystallisation Methods 0.000 title claims abstract description 87
- 230000008025 crystallization Effects 0.000 title claims abstract description 87
- 239000007788 liquid Substances 0.000 claims abstract description 199
- 238000001816 cooling Methods 0.000 claims abstract description 36
- 230000007246 mechanism Effects 0.000 claims abstract description 25
- 239000012452 mother liquor Substances 0.000 claims abstract description 25
- 239000002562 thickening agent Substances 0.000 claims abstract description 20
- 238000004140 cleaning Methods 0.000 claims description 19
- 239000012530 fluid Substances 0.000 claims description 12
- 239000000110 cooling liquid Substances 0.000 claims description 4
- 239000002994 raw material Substances 0.000 abstract description 8
- 238000007599 discharging Methods 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 35
- 239000013078 crystal Substances 0.000 description 13
- 230000009471 action Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000001035 drying Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000005119 centrifugation Methods 0.000 description 3
- 230000008676 import Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 150000003585 thioureas Chemical class 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- FFEARJCKVFRZRR-BYPYZUCNSA-N L-methionine Chemical compound CSCC[C@H](N)C(O)=O FFEARJCKVFRZRR-BYPYZUCNSA-N 0.000 description 1
- LGRFSURHDFAFJT-UHFFFAOYSA-N Phthalic anhydride Natural products C1=CC=C2C(=O)OC(=O)C2=C1 LGRFSURHDFAFJT-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- JHIWVOJDXOSYLW-UHFFFAOYSA-N butyl 2,2-difluorocyclopropane-1-carboxylate Chemical compound CCCCOC(=O)C1CC1(F)F JHIWVOJDXOSYLW-UHFFFAOYSA-N 0.000 description 1
- MYFXBBAEXORJNB-UHFFFAOYSA-N calcium cyanamide Chemical compound [Ca+2].[N-]=C=[N-] MYFXBBAEXORJNB-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008396 flotation agent Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229930182817 methionine Natural products 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 125000001741 organic sulfur group Chemical group 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- JNMRHUJNCSQMMB-UHFFFAOYSA-N sulfathiazole Chemical compound C1=CC(N)=CC=C1S(=O)(=O)NC1=NC=CS1 JNMRHUJNCSQMMB-UHFFFAOYSA-N 0.000 description 1
- 229960001544 sulfathiazole Drugs 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 230000007306 turnover Effects 0.000 description 1
- 238000004073 vulcanization Methods 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a thiourea continuous crystallization system, which comprises a precooler, a crystallizer, a thickener, a centrifuge and a mother liquor tank which are sequentially connected through pipelines; n groups of cooling mechanisms are arranged on the crystallizer, and each group of cooling mechanisms comprises an external cooler and a crystallization circulating pump; thiourea solution enters the crystallizer from a liquid inlet pipe b, and because the length of the liquid inlet pipe b is smaller than that of the liquid inlet pipe a, thiourea with high temperature is positioned at the upper layer, thiourea with low temperature is positioned at the lower layer, and thiourea with low temperature is kept in the lower part of the crystallizer for crystallization and is kept in the thickener through a discharge hole, the problem that the thiourea solution which just enters the crystallizer during discharging inevitably flows out along with the crystallized thiourea, so that raw material waste is caused is solved; meanwhile, the problem that thiourea is easy to agglomerate and poor in quality due to the fact that the temperature of the thiourea suddenly drops when the thiourea is cooled by a single cooling mechanism is solved.
Description
Technical Field
The invention belongs to the field of thiourea production, and particularly relates to a thiourea continuous crystallization system.
Background
Thiourea is an organic sulfur-containing compound, is an important raw material in pharmaceutical industry, is used for synthesizing medicines such as sulfathiazole, methionine, pig fattening and the like, can be used as a raw material of dye, a dyeing assistant, resin and molding powder, and can also be used as a vulcanization accelerator of rubber, a flotation agent of metal minerals, a catalyst for preparing phthalic anhydride and fumaric acid and the like.
The current industrial production method of thiourea is as follows: water, lime nitrogen and hydrogen sulfide gas are adopted as raw materials, and absorption synthesis reaction is carried out in a synthesis kettle to prepare suspension containing thiourea; and filtering and purifying the suspension for multiple times, cooling and crystallizing, centrifugally drying crystals after solid-liquid separation, and drying to obtain a finished product. Among them, crystallization is one of the key links for preparing high-quality thiourea. The cooling crystallization comprises clearance cooling crystallization and continuous cooling crystallization, and the clearance cooling crystallization has the advantages of simple production equipment and strong production controllability, but the industrial large-scale production efficiency is low; continuous cooling crystallization has the advantage that business turn over material is continuous stable, production efficiency is high, nevertheless because set up agitating unit in the crystallizer, agitating unit can mix the thiourea solution that just gets into the crystallizer with the thiourea of crystallization, therefore just get into the thiourea solution of crystallizer during the ejection of compact and inevitably flow out thereupon to cause the raw materials extravagant.
Disclosure of Invention
The invention mainly aims to provide a thiourea continuous crystallization system, which can solve the technical problem that thiourea solution which just enters a crystallizer during discharging inevitably flows out along with crystallized thiourea, so that raw material is wasted.
A thiourea continuous crystallization system comprises a precooler, a crystallizer, a thickener, a centrifuge and a mother liquor tank which are sequentially connected through pipelines; n groups of cooling mechanisms are arranged on the crystallizer, and each group of cooling mechanisms comprises an external cooler and a crystallization circulating pump;
the top of the crystallizer is provided with a feed inlet and n circulation ports, and the bottom of the crystallizer is provided with a discharge outlet and is connected with the thickener through a pipeline; a feeding mechanism is arranged in the feeding hole, a crystallization circulating pump is arranged in the circulating hole, a first inlet of the crystallization circulating pump is connected with a feeding pipe, the feeding pipe extends into the crystallizer, and a first outlet of the crystallization circulating pump is connected with a second inlet of the external cooler through a pipeline;
the feeding mechanism comprises a feeding table, a liquid inlet pipe a and n liquid inlet pipes b, the feeding table is arranged at the top of the crystallizer, and the liquid inlet pipe a and the n liquid inlet pipes b are fixed at the bottom of the feeding table and extend into the crystallizer;
a liquid inlet a and a liquid inlet b are respectively arranged on the feeding platforms corresponding to the liquid inlet pipe a and the liquid inlet pipe b, the liquid inlet a is communicated with the liquid inlet pipe a, and the liquid inlet b is communicated with the liquid inlet pipe b; one liquid inlet b is connected with a mother liquor pipeline, and the other liquid inlets b are connected with a second outlet of the external cooler through a pipeline;
the lengths of the n liquid inlet pipes b are different and are all smaller than that of the liquid inlet pipe a; the shortest liquid inlet pipe b and the longest liquid inlet pipe b are both x, and the longest liquid inlet pipe b are both x + (n-1) y;
according to the length of the liquid inlet pipe b, the liquid inlet pipes from short to long are sequentially named as a first liquid inlet pipe and a second liquid inlet pipe … … nth liquid inlet pipe, liquid inlets b corresponding to the liquid inlet pipes b are sequentially named as a first liquid inlet and a second liquid inlet … … nth liquid inlet, external coolers connected with the liquid inlet pipes b are sequentially named as a first external cooler and a second external cooler … … nth external cooler, and crystallization circulating pumps connected with the external coolers are sequentially named as a first crystallization circulating pump and a second crystallization circulating pump … … nth crystallization circulating pump; the feeding pipes on the crystallization circulating pump are sequentially named as a first feeding pipe and a second feeding pipe … … nth feeding pipe;
the first liquid inlet is connected with a first liquid inlet pipe, a first outlet of the first crystallization circulating pump is connected with a second inlet of the first external cooler, and a second outlet of the first external cooler is connected with the second liquid inlet;
a first outlet of the second crystallization circulating pump is connected with a second inlet of the second external cooler, and a second outlet of the second external cooler is connected with the nth liquid inlet;
a first outlet of the nth crystallization circulating pump is connected with a second inlet of the nth external cooler, and a second outlet of the nth external cooler is connected with the liquid inlet a;
the refrigerating fluid sequentially enters the nth external cooler … …, the second external cooler and the first external cooler.
Preferably, the liquid inlet pipe b is arranged in the liquid inlet pipe a;
the bottom of the liquid inlet pipe b is connected with a liquid outlet pipe through a bent pipe, and the other end of the liquid outlet pipe penetrates through the liquid inlet pipe a and is arranged outside the liquid inlet pipe b.
Preferably, the plurality of liquid inlet pipes b are coaxially disposed.
Preferably, an auxiliary circulating pump is connected between the refrigerating fluid inlet and the refrigerating fluid outlet of the external cooler through a pipeline.
Preferably, the bottom of the external cooler is provided with a cleaning inlet, and a cleaning outlet is arranged above one side of the external cooler; the cleaning liquid is connected with the cleaning liquid inlet through a pipeline, and the cleaning outlet is connected with the fourth inlet of the mother liquid tank through a pipeline.
Preferably, the device further comprises a precooler, the mother liquor pipeline is connected with a third inlet of the precooler, and a third outlet of the precooler is connected with the liquid inlet a.
Preferably, the fourth outlet of the mother liquor tank is connected with the third inlet or the liquid inlet a of the precooler through a pipeline.
The invention has the beneficial effects that:
1) thiourea solution enters the crystallizer from a liquid inlet pipe b, and because the length of the liquid inlet pipe b is smaller than that of the liquid inlet pipe a, the thiourea solution just entering the crystallizer is positioned above the inside of the crystallizer, and the crystallized thiourea is positioned below the inside of the crystallizer and flows to the thickener through a discharge hole; the cooling mechanisms can respectively carry out circulating cooling on the thiourea at different depths, and the thiourea solution in the crystallizer is subjected to circulating disturbance through a crystallization circulating pump of the cooling mechanism, so that crystals can be prevented from being accumulated and agglomerated at the bottom of the crystallizer without a stirring device, the temperature of the thiourea in the crystallizer is different due to the arrangement of the cooling mechanisms, and the temperature of the thiourea in the crystallizer is gradually decreased from top to bottom, so that the problem that the thiourea solution which just enters the crystallizer during discharging inevitably flows out along with the crystallized thiourea, and the raw material waste is caused is solved; meanwhile, the problem that thiourea is easy to agglomerate and poor in quality due to sudden temperature drop of thiourea when the thiourea is cooled by a single cooling mechanism is solved;
2) the refrigerating fluid of external cooler enters into the n external cooler … … second external cooler in proper order, first external cooler, the low-temperature's of refrigerating fluid cools off the thiourea solution of below low temperature in the crystallizer promptly, the high-temperature's of refrigerating fluid cools off the high thiourea solution of top temperature in the crystallizer, make in the crystallizer from first feed liquor pipe, the thiourea temperature that second feed liquor pipe … … nth feed liquor pipe came out diminishes progressively, thereby can slowly cool down the thiourea, the crystallization quality of thiourea has been guaranteed, make the crystal granule stable, the problem of the abrupt temperature drop crystal caking has been avoided.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic view of a feed mechanism according to the present invention;
FIG. 3 is a cross-sectional view of FIG. 2;
FIG. 4 is a schematic structural diagram of another feeding mechanism of the present invention.
In the figure:
1. a crystallizer; 2. a precooler; 3. a thickener; 4. a centrifuge; 5. a mother liquor tank; 6. cleaning the tank; 7. a crystallization circulating pump; 8. an external cooler; 9. an auxiliary circulation pump; 10. a feed pipe; 11. a liquid inlet pipe a; 12. a liquid inlet pipe b; 13. a feeding table; 14. a first circulation pump; 15. an electromagnetic valve; 16. a liquid outlet pipe; 17. a liquid inlet a; 18. a liquid inlet b;
701. a first crystallization circulating pump; 702. a second crystallization circulating pump; 703. an nth crystallization circulating pump;
801. a first external cooler; 802. a second external cooler; 803. the nth external cooler;
901. a first auxiliary circulation pump; 902. a second auxiliary circulation pump; 903. the nth auxiliary circulating pump;
1001. a first feed tube; 1002 a second feed pipe; 1003. an nth feeding pipe;
1201. a first liquid inlet pipe; 1202 a second liquid inlet pipe; 1203. the nth liquid inlet pipe;
1801. a first liquid inlet; 1802. a second liquid inlet; 1803. an nth liquid inlet.
Detailed Description
Referring to fig. 1-4, which are an embodiment of the thiourea continuous crystallization system of the present invention, the system includes a crystallizer 1, a thickener 3, a centrifuge 4, and a mother liquor tank 5, which are connected in sequence through pipes; n groups of cooling mechanisms are arranged on the crystallizer 1, and each group of cooling mechanisms comprises an external cooler 8 and a crystallization circulating pump 7; thiourea solution enters the crystallizer 1 through a pipeline, and the thiourea solution in the crystallizer 1 realizes heat exchange under the action of a crystallization circulating pump 7 and an external cooler 8, so that the purpose of cooling and crystallizing is achieved; the thiourea crystallized in the crystallizer 1 enters a thickener 3 and then enters a centrifuge 4 for separation, the separated thiourea enters the next procedure, namely a drying stage, and the filtrate enters a mother liquor tank 5.
The initial temperature of the thiourea solution was 60 ℃. + -. 5 ℃ and the mass concentration of thiourea was 25%. + -. 5%.
The thickener 3 is a settler capable of concentrating thiourea crystals in liquid, the retention time of the thiourea crystals in the thickener 3 is 1h, so that thiourea crystals in the thickener 3 are positioned at the lower part, clear liquid is positioned at the upper part, the thiourea crystals at the lower layer enter a centrifuge 4 for centrifugation, and the clear liquid at the upper layer can enter a mother liquor tank 5 through a pipeline.
The top of the crystallizer 1 is provided with a feed inlet and n circulation ports, the bottom of the crystallizer is provided with a discharge outlet and is connected with the thickener 3 through a pipeline, so that crystallized thiourea can flow into the thickener 3 through the discharge outlet; be provided with feed mechanism in the feed inlet, thiourea solution passes through feed mechanism in continuous entering into crystallizer 1, be provided with crystallization circulating pump 7 in the circulation mouth, crystallization circulating pump 7 can cause the thiourea in crystallizer 1 to the cooling of external cooler 8 realization to the thiourea, crystallization circulating pump 7's first access connection has inlet pipe 10, inlet pipe 10 extends to in crystallizer 1, the first export of crystallization circulating pump 7 passes through the pipe connection with the second import of external cooler 8, can deliver to external cooler 8 with the thiourea solution in crystallizer 1, the external cooler 8 cools down, thiourea after the cooling again enters into crystallizer 1 through inlet pipe 10, thereby realize the thiourea crystallization. Wherein the circulation speed of the crystallization circulation pump 7 is 1000 m/h.
The feeding mechanism comprises a feeding table 13, a liquid inlet pipe a 11 and n liquid inlet pipes b 12, the feeding table 13 is arranged at the top of the crystallizer 1, and the liquid inlet pipe a 11 and the n liquid inlet pipes b 12 are fixed at the bottom of the feeding table 13 and extend into the crystallizer 1; the length of the liquid inlet pipe a 11 is greater than that of the liquid inlet pipe b 12, and the outlet of the liquid inlet pipe a 11 is arranged below the outlet of the liquid inlet pipe b 12; a liquid inlet a 17 and a liquid inlet b 18 are respectively arranged on the feeding platform 13 corresponding to the liquid inlet pipe a 11 and the liquid inlet pipe b 12; the liquid inlet a 17 is communicated with a liquid inlet pipe a 11, and the liquid inlet b 18 is communicated with a liquid inlet pipe b 12; one liquid inlet b 18 is connected with a mother liquor pipeline, and the other liquid inlets b 18 are connected with a second outlet of the external cooler 8 through pipelines; in the same circulation, if thiourea mother liquor enters a crystallizer from a liquor inlet pipe b, the crystallized thiourea mother liquor is cooled under the action of a feed pipe 10, a crystallization circulating pump and an external cooler, and the length of the liquor inlet pipe b in the circulation is equal to that of a feed pipe 10 in the circulation; the number of the liquid inlet pipes b 12 is the same as that of the cooling mechanisms. Thiourea solution enters the crystallizer 1 from a liquid inlet pipe b 12, and the thiourea flowing out from the liquid inlet pipe b 12 is positioned above the liquid inlet pipe a 11 because the length of the liquid inlet pipe b 12 is smaller than that of the liquid inlet pipe a 11; furthermore, in the same circulation, the length of the liquid inlet pipe b 12 is equal to that of the material inlet pipe 10, so under the action of the crystallization circulating pump 7, thiourea solution flowing out of the liquid inlet pipe b 12 can be brought into the cooler by the material inlet pipe 10 and the crystallization circulating pump 7, and is cooled by the cooler, the cooled thiourea solution enters the crystallizer 1 through the liquid inlet pipe a 11, and as the length of the liquid inlet pipe a 11 is greater than that of the liquid inlet pipe b 12, thiourea with high temperature is on the upper layer, thiourea with low temperature is on the lower layer, and thiourea with low temperature is crystallized below the crystallizer 1 and enters the thickener 3 through the material outlet, so that the problem that the thiourea solution which just enters the crystallizer during discharging inevitably flows out along with the crystallized thiourea, and raw material waste is caused.
It should be noted that the thiourea solution flows into the crystallizer 1 through the liquid inlet pipe b 12, and the thiourea cooled by the external cooler 8 flows into the crystallizer 1 through the liquid inlet pipe a 11, so that the thiourea in different heights in the crystallizer 1 has different temperatures, that is, the thiourea in the upper layer has a high temperature, and the thiourea in the lower layer has a low temperature; the thiourea with higher temperature flows to the lower part of the crystallizer 1 after being cooled by the external cooler 8, and the thiourea below the crystallizer 1 can realize crystallization due to low temperature, so that the system has the purpose of continuous crystallization.
When n is more than or equal to 3, the lengths of the liquid inlet pipes b 12 are different and are smaller than the length of the liquid inlet pipe a 11. Here, the shortest liquid inlet pipe b 12 and the feed pipe 10 may have a length of x, and the longest liquid inlet pipe b 12 and the longest feed pipe 10 may have a length of x + (n-1) y. The number, x and y of the liquid inlet pipe b 12 and the cooling mechanism are adjusted according to the size of the crystallizer, and are not limited herein. For example, when the height of the mold is 2m, x is 50cm, y is 40cm, and n may be 3.
In addition, according to the length of the liquid inlet pipe b 12, from short to long, the liquid inlet pipe b can be named as a first liquid inlet pipe 1201 and a second liquid inlet pipe 1202 … … nth liquid inlet pipe 1203 in sequence, a liquid inlet b 18 corresponding to the liquid inlet pipe b 12 is named as a first liquid inlet 1801 and a second liquid inlet 1802 … … nth liquid inlet 1803 in sequence, an external cooler 8 connected with the liquid inlet pipe b 12 is named as a first external cooler 801 and a second external cooler 802 … … nth external cooler 803 in sequence, a crystallization circulating pump 7 connected with the external cooler 8 is named as a first crystallization circulating pump 701 and a second crystallization circulating pump 702 … … nth crystallization circulating pump 703 in sequence, and a feeding pipe 10 on the crystallization circulating pump is named as a first feeding pipe 1001 and a second feeding pipe 1002 … … nth feeding pipe 1003 in sequence.
Mother liquor enters the crystallizer 1 through a first liquid inlet 1801 and a first liquid inlet pipe 1201, a first outlet of the first crystallization circulating pump 701 is connected with a second inlet of the first external cooler 801, and a second outlet of the first external cooler 801 is connected with a second liquid inlet 1802;
a first outlet of the second crystallization circulating pump 702 is connected with a second inlet of the second external cooler 802, and a second outlet of the second external cooler 802 is connected with an n-th liquid inlet 1803;
a first outlet of the nth crystallization circulating pump 703 is connected with a second inlet of the nth external cooler 803, and a second outlet of the nth external cooler 803 is connected with a liquid inlet a 17.
As described above, the plurality of cooling mechanisms may respectively perform the circulating cooling of the thioureas at different depths, so that the plurality of thioureas at different temperatures exist in the crystallizer 1; and the crystallization circulating pump of cooling body can carry out circulation disturbance with the thiourea solution in the crystallizer, need not agitating unit and also can prevent that the crystal from piling up, caking in the crystallizer bottom, avoided single cooling body when cooling thiourea, because thiourea temperature dip leads to, the poor problem of thiourea quality.
It should be noted that the liquid inlet pipe a 11 and the n liquid inlet pipes b 12 may be respectively and independently disposed, or the n liquid inlet pipes b 12 are disposed in the liquid inlet pipe a 11. When the liquid inlet pipe a 11 and the n liquid inlet pipes b 12 are respectively and independently arranged, that is, the inner diameters of the liquid inlet pipe a 11 and the liquid inlet pipes b 12 can be the same or different and are respectively and independently arranged at the bottom of the feeding table 13, the liquid inlet pipe b 12 at the moment can be in an L shape or a vertical shape, and no limitation is provided; and when feed liquor pipe b 12 set up in feed liquor pipe a 11, the internal diameter of feed liquor pipe a 11 was greater than the external diameter of feed liquor pipe b 12 this moment, a plurality of feed liquor pipe b 12 can independently set up in feed liquor pipe a 11, also can set up with the axle center, a plurality of feed liquor pipe b 12 can set up in feed liquor pipe a 11 each other independently promptly, or a plurality of feed liquor pipe b 12 set up with the axle center, and feed liquor pipe b 12 is the L type this moment (the bottom of feed liquor pipe b 12 has drain pipe 16 through the elbow connection, the drain pipe 16 other end passes feed liquor pipe a 11 and sets up outside feed liquor pipe a 11).
Wherein, in particular embodiments, effluent channel 16 may be disposed horizontally or obliquely, as the present invention is not limited in this respect.
It should be noted that the sudden temperature decrease of thiourea inevitably affects the crystallization effect of thiourea, and therefore, in a specific implementation, an auxiliary circulation pump 9 is connected between the refrigerant inlet and the refrigerant outlet of the external cooler 8 through a pipe. The auxiliary circulation pump 9 is named as a first auxiliary circulation pump 901, a second auxiliary circulation pump 902 … …, and an nth auxiliary circulation pump 903 in this order according to the external cooler connected thereto.
In addition, the cooling liquid of the external cooler 8 sequentially enters the nth external cooler 803 … …, the second external cooler 802 and the first external cooler 801. Adopt same refrigerating fluid to cool down different external coolers 8, can not only reduce the energy consumption, but also can improve thiourea crystallization quality, the refrigerating fluid comes from factory refrigerated water unit, and its initial temperature is 5 ℃. Because the refrigerating fluid sequentially enters different external coolers 8, the temperatures of the refrigerating fluid entering the external coolers 8 are different, and the cooling temperature of the thiourea is also different. That is to say, the temperature of the cooling liquid entering the nth external cooler 803 … …, the second external cooler 802 and the first external cooler 801 increases progressively, that is, the temperature of the thiourea coming out of the nth liquid inlet pipe 1203 of the first liquid inlet pipe 1201 and the second liquid inlet pipe 1202 … … in the crystallizer 1 decreases progressively, so that the thiourea can be cooled slowly, the crystallization quality of the thiourea is ensured, and the crystal particles are stable.
In a specific implementation, in the process of cooling thiourea by the external cooler 8, part of thiourea solution remains in the external cooler 8, in order to clean the thiourea solution in the external cooler 8 and keep the interior of the external cooler 8 clean, steam from a preheating boiler respectively enters the bottom of the external cooler 8 and is provided with a cleaning inlet, the external cooler 8 is cleaned by the steam, and condensate or steam flows out of a cleaning outlet to the mother liquor tank 5; the cleaning inlet is connected with the fifth outlet of the cleaning tank and the cleaning outlet is connected with the fourth inlet of the mother liquor tank 5 through pipelines. Wherein, the condensate in the washing liquid tank at the beginning can enter the mother liquid tank 5 because the thiourea content is relatively large, and the condensate flowing into the washing liquid tank at the later stage can be used for softening the water tank because the thiourea content is low
In a specific implementation, the device further comprises a precooler 2, a mother liquor pipeline is connected with a third inlet of the precooler 2, and a third outlet of the precooler 2 is connected with a liquid inlet a 17. Before the thiourea solution enters the crystallizer 1, the thiourea solution is introduced into the precooler 2 for precooling, and heat exchange is carried out on the mother solution, so that the influence of thiourea on the crystallization quality in the subsequent crystallizer 1 due to sudden temperature drop is avoided.
The precooler 2 is not limited in the invention, and a commercially available precooler 2 commonly used in the field can be adopted.
Wherein, because supernatant contains thiourea in the centrifugation, in order to avoid thiourea loss, mother liquor tank 5 is connected with third import or inlet a 17 of precooler 2 through the pipeline, the mother liquor after centrifugation enters precooler 2 or crystallizer 1 to carry out cooling crystallization work. It should be noted that the supernatant of the thickener 3 and the liquid for cleaning the external cooler 8 both contain thiourea, and the two liquid portions also enter the mother liquid tank 5 under the connection of the pipelines, and the fourth outlet of the mother liquid tank 5 is connected with the third inlet or liquid inlet a 17 of the precooler 2 through the pipeline.
In order to control the entrance of thiourea, other liquids, and vapors, the solenoid valves 15 are provided in the respective pipes, and the type of the solenoid valve 15 is not limited herein, and a commercially available solenoid valve 15 may be used.
Further, the first circulation pump 14 is provided in both the pipe connecting the cleaning tank 6 and the mother liquid tank 5 and the pipe connecting the mother liquid tank 5 and the precooler 2 or the crystallizer 1, and a commercially available first circulation pump 14 may be used without limiting the signal of the first circulation pump 14.
The working flow of the invention is illustrated in connection with fig. 1-4:
when the height of the crystallizer is 2m, x is 50cm, y is 40cm, and n can be 3;
the thiourea solution with the initial temperature of 60 +/-5 ℃ and the mass concentration of 25% +/-5% in the thiourea solution enters a precooler 2 through a mother liquor pipeline for heat exchange, so that the temperature of the thiourea solution is reduced to 40 +/-5 ℃, the low-temperature thiourea solution enters a crystallizer 1 through a first liquid inlet pipe 1201, the thiourea solution in the crystallizer 1 primarily circularly cools the thiourea solution entering the crystallizer 1 under the action of a first feed pipe 1001, a first crystallization circulating pump 701 and a first external cooler 801, the cooled thiourea enters the crystallizer 1 through a second liquid inlet pipe 1202, circularly cools the thiourea solution entering the crystallizer 1 under the action of a second feed pipe 1002, a second crystallization circulating pump 702 and a second external cooler 802, and the thiourea solution is sequentially cooled according to the steps until the thiourea solution in the crystals is circularly cooled under the action of a third feed pipe, a third crystallization circulating pump and a third external cooler, the cooled thiourea enters the crystallizer 1 from a liquid inlet pipe a 11. Wherein three crystallization circulating pump 7's circulation speed is 1000m and educes a year/h, and the refrigerating fluid that outer cooler 8 adopted comes from factory freezing water unit, and its initial temperature is 5 ℃, and it enters into third outer cooler … … second outer cooler 802, first outer cooler 801 in proper order and carries out circulative cooling to the thiourea, and above-mentioned cooling cycle process can make the thiourea slowly cool down, improves thiourea crystallization quality for the crystal granule is stable, avoids the caking.
Thiourea (the temperature is below 14 ℃) cooled by a third external cooler enters the lower part of a crystallizer 1, the crystallized thiourea enters a thickener 3 through a discharge port, the thiourea is concentrated for 1h in the thickener 3, supernatant in the thickener 3 enters a mother liquor tank 5, crystals in the lower layer enter a centrifugal machine 4 for separation, the separated thiourea enters the next procedure drying stage, and filtrate enters the mother liquor tank 5. The liquid in the mother liquid tank 5 can enter the precooler or the cooler again for the next cooling crystallization work.
Thiourea crystallization is finished, and the steam that comes from exhaust-heat boiler enters into the clean import of external cooler 8 respectively, carries out cleaning work to external cooler 8, and the initial cleaning solution enters into mother liquor jar 5, and the later stage cleaning solution is used for softening the water tank.
The foregoing description is only of the preferred embodiments of the present invention, and it should be understood that the described embodiments are only a few, and not all, of the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (7)
1. A thiourea continuous crystallization system comprises a precooler, a crystallizer, a thickener, a centrifuge and a mother liquor tank which are sequentially connected through pipelines; the crystallizer is characterized in that n groups of cooling mechanisms are arranged on the crystallizer, and each group of cooling mechanisms comprises an external cooler and a crystallization circulating pump;
the top of the crystallizer is provided with a feed inlet and n circulation ports, and the bottom of the crystallizer is provided with a discharge outlet and is connected with the thickener through a pipeline; a feeding mechanism is arranged in the feeding hole, a crystallization circulating pump is arranged in the circulating hole, a first inlet of the crystallization circulating pump is connected with a feeding pipe, the feeding pipe extends into the crystallizer, and a first outlet of the crystallization circulating pump is connected with a second inlet of the external cooler through a pipeline;
the feeding mechanism comprises a feeding table, a liquid inlet pipe a and n liquid inlet pipes b, the feeding table is arranged at the top of the crystallizer, and the liquid inlet pipe a and the n liquid inlet pipes b are fixed at the bottom of the feeding table and extend into the crystallizer;
a liquid inlet a and a liquid inlet b are respectively arranged on the feeding platforms corresponding to the liquid inlet pipe a and the liquid inlet pipe b, the liquid inlet a is communicated with the liquid inlet pipe a, and the liquid inlet b is communicated with the liquid inlet pipe b; one liquid inlet b is connected with a mother liquor pipeline, and the other liquid inlets b are connected with a second outlet of the external cooler through a pipeline;
the lengths of the n liquid inlet pipes b are different and are all smaller than that of the liquid inlet pipe a; the shortest liquid inlet pipe b and the longest liquid inlet pipe b are both x, and the longest liquid inlet pipe b are both x + (n-1) y;
according to the length of the liquid inlet pipe b, the liquid inlet pipes from short to long are named as a first liquid inlet pipe and a second liquid inlet pipe … … nth liquid inlet pipe in sequence, liquid inlets b corresponding to the liquid inlet pipes b are named as a first liquid inlet and a second liquid inlet … … nth liquid inlet in sequence, external coolers connected with the liquid inlet pipes b are named as a first external cooler and a second external cooler … … nth external cooler in sequence, and crystallization circulating pumps connected with the external coolers are named as a first crystallization circulating pump and a second crystallization circulating pump … … nth crystallization circulating pump in sequence; the feeding pipes on the crystallization circulating pump are sequentially named as a first feeding pipe and a second feeding pipe … … nth feeding pipe;
the first liquid inlet is connected with a first liquid inlet pipe, a first outlet of the first crystallization circulating pump is connected with a second inlet of the first external cooler, and a second outlet of the first external cooler is connected with the second liquid inlet;
a first outlet of the second crystallization circulating pump is connected with a second inlet of the second external cooler, and a second outlet of the second external cooler is connected with the nth liquid inlet;
a first outlet of the nth crystallization circulating pump is connected with a second inlet of the nth external cooler, and a second outlet of the nth external cooler is connected with the liquid inlet a;
the refrigerating fluid sequentially enters the nth external cooler … …, the second external cooler and the first external cooler.
2. The continuous crystallization system of thiourea according to claim 1, wherein the liquid inlet pipe b is disposed in the liquid inlet pipe a;
the bottom of the liquid inlet pipe b is connected with a liquid outlet pipe through an elbow pipe, and the other end of the liquid outlet pipe penetrates through the liquid inlet pipe a and is arranged outside the liquid inlet pipe b.
3. The continuous crystallization system of thiourea according to claim 2, wherein the plurality of liquid inlet pipes b are coaxially arranged.
4. The continuous thiourea crystallization system of claim 1, wherein an auxiliary circulation pump is connected between the cooling liquid inlet and the cooling liquid outlet of the external cooler through a pipe.
5. The continuous crystallization system of thiourea according to claim 1, wherein the bottom of the external cooler is provided with a clean inlet, and the upper side of one side is provided with a clean outlet; the cleaning liquid is connected with the cleaning liquid inlet through a pipeline, and the cleaning outlet is connected with the fourth inlet of the mother liquid tank through a pipeline.
6. The continuous crystallization system of thiourea of claim 1, further comprising a precooler, wherein the mother liquor pipeline is connected with a third inlet of the precooler, and a third outlet of the precooler is connected with the liquid inlet a.
7. The continuous crystallization system of thiourea according to claim 6, wherein the fourth outlet of the mother liquid tank is connected with the third inlet or the liquid inlet a of the precooler through a pipeline.
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| EP0119978A2 (en) * | 1983-02-15 | 1984-09-26 | Monsanto Company | Incrustation resistive crystallizer |
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| CN214050523U (en) * | 2020-12-22 | 2021-08-27 | 河北金坦化工装备有限公司 | Cooling crystallization device for recovering metal ions from waste acid solution |
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| DE102008029050A1 (en) * | 2008-06-18 | 2009-12-24 | Gea Messo Gmbh | Process and apparatus for the continuous production of a crystallizate with constant particle size distribution |
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|---|---|---|---|---|
| EP0119978A2 (en) * | 1983-02-15 | 1984-09-26 | Monsanto Company | Incrustation resistive crystallizer |
| CN207187160U (en) * | 2017-06-28 | 2018-04-06 | 河北诺达化工设备有限公司 | A kind of OSLO crystallization apparatus |
| CN208990284U (en) * | 2018-10-17 | 2019-06-18 | 四川金象赛瑞化工股份有限公司 | A kind of material directly contacts cooling crystallizer with refrigerant |
| CN110772829A (en) * | 2019-10-25 | 2020-02-11 | 安徽金轩科技有限公司 | Cooling crystallization equipment for purifying furanone |
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