CN116672967A - Depolymerization kettle for biodegradable material and process thereof - Google Patents
Depolymerization kettle for biodegradable material and process thereof Download PDFInfo
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- CN116672967A CN116672967A CN202210160402.2A CN202210160402A CN116672967A CN 116672967 A CN116672967 A CN 116672967A CN 202210160402 A CN202210160402 A CN 202210160402A CN 116672967 A CN116672967 A CN 116672967A
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- depolymerization
- tube plate
- kettle
- lactide
- depolymerization kettle
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- 239000000463 material Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 42
- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000007788 liquid Substances 0.000 claims abstract description 26
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000004310 lactic acid Substances 0.000 claims abstract description 11
- 235000014655 lactic acid Nutrition 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 238000003780 insertion Methods 0.000 claims abstract description 8
- 230000037431 insertion Effects 0.000 claims abstract description 8
- 239000012071 phase Substances 0.000 claims abstract 7
- 239000003054 catalyst Substances 0.000 claims description 6
- 238000009833 condensation Methods 0.000 claims description 3
- 230000005494 condensation Effects 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims 3
- 239000007792 gaseous phase Substances 0.000 claims 2
- 229920000747 poly(lactic acid) Polymers 0.000 abstract description 5
- 239000004626 polylactic acid Substances 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000006116 polymerization reaction Methods 0.000 abstract description 2
- 125000004122 cyclic group Chemical group 0.000 abstract 1
- 239000007791 liquid phase Substances 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical group ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 2
- 229910001887 tin oxide Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- JJTUDXZGHPGLLC-IMJSIDKUSA-N 4511-42-6 Chemical compound C[C@@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-IMJSIDKUSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000011208 chromatographic data Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/002—Component parts of these vessels not mentioned in B01J3/004, B01J3/006, B01J3/02 - B01J3/08; Measures taken in conjunction with the process to be carried out, e.g. safety measures
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/006—Processes utilising sub-atmospheric pressure; Apparatus therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/02—Feed or outlet devices therefor
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D319/00—Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D319/10—1,4-Dioxanes; Hydrogenated 1,4-dioxanes
- C07D319/12—1,4-Dioxanes; Hydrogenated 1,4-dioxanes not condensed with other rings
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
Abstract
The application discloses a depolymerization kettle for biodegradable materials and a process thereof, which belong to the technical field of polylactic acid production, wherein oligomers generated by lactic acid pre-polymerization are conveyed upwards along a central circulating pipe through a spiral propeller after entering the depolymerization kettle through a feed inlet, the oligomers conveyed to the top end of the central circulating pipe are uniformly distributed into a heat exchange pipe through a distributor, feed liquid is heated by a heating medium, partial oligomers are depolymerized to generate lactide, lactide and unreacted oligomers flow to the bottom of the depolymerization kettle along the heat exchange pipe, the lactide is in a gaseous state at the working temperature and the pressure, gas-liquid two phases are separated under the depolymerization kettle, the gas phase is discharged out of the depolymerization kettle under the vacuum effect, the liquid phase is gathered at the bottom and is conveyed to the upper part of the depolymerization kettle through the spiral propeller, and the cyclic operation is performed; a liquid baffle or an insertion pipe is arranged at the gas phase outlet of the crude lactide, so that gas-liquid entrainment can be effectively prevented, and oligomer liquid is prevented from entering the gas phase pipe of the lactide.
Description
Technical Field
The application relates to the technical field of polylactic acid production, in particular to a depolymerization kettle for biodegradable materials and a process thereof.
Background
With the increasing environmental problems and the rising green chemistry, the research of biodegradable materials has been attracting more attention, and especially polylactic acid has become a research hotspot in recent years. This is because polylactic acid has excellent biodegradability, compatibility and absorbability, and is converted into lactic acid existing in the living body, and can be finally converted into carbon dioxide and water in the natural world and the living body.
The patent with application number CN201110001115.9 discloses an improved method for preparing lactide as a polylactic acid intermediate, wherein a preparation method of lactide is introduced, lactic acid is dehydrated by a general chemical reactor with heating and stirring in vacuum, the temperature is controlled to be 150-220 ℃, lactic acid oligomer is obtained after dehydration is completed, then the oligomer is added into a catalyst, and then is conveyed into an oligomer high-level tank by a conveying tool such as a pump and then enters a lactide distiller, the distiller is one of a rotary film distiller, a falling film distiller or a molecular distiller, then distillation is carried out at the temperature of 150-240 ℃ in a high vacuum environment, the produced lactide enters a condenser in the form of steam for condensation and then is collected, the oligomer without depolymerization is continuously distilled from the bottom of the distiller by pump circulation, and new oligomer is continuously supplemented after the circulating material is reduced, so that the distillation process is completed;
however, the lactide disclosed in the patent has two problems in the preparation process, namely, the viscosity of the oligomer per se after lactic acid dehydration is high, and generally, a gear pump is used for conveying high-viscosity materials, and the conveying maximum flow rate of the gear pump is 55m 3 And/h, the size of the depolymerization kettle is limited, the productivity is limited, and a larger production line can only adopt a plurality of depolymerization kettles to produce simultaneously so as to meet the productivity; secondly, in the traditional external circulation depolymerization kettle, the structure is complex, the occupied area is large, and certain heat loss exists, so that an efficient and amplified depolymerization kettle for biodegradable materials and a lactide depolymerization device for the process thereof are urgently needed to improve the depolymerization efficiency.
Disclosure of Invention
The application provides a depolymerization kettle for biodegradable materials and a process thereof, which are used for solving the existing problems.
In order to achieve the above purpose, the present application adopts the following technical scheme:
a depolymerization tank for biodegradable materials, comprising: the depolymerization kettle comprises a depolymerization kettle body, a spiral propeller and a driving motor, wherein the driving motor is arranged below the bottom of the depolymerization kettle body, the upper end of a main shaft of the driving motor extends into the depolymerization kettle body and is detachably connected with the lower end of the spiral propeller, and the upper side of the spiral propeller is movably sleeved in the lower end of a central circulating pipe;
an upper tube plate and a lower tube plate are respectively and fixedly arranged above the middle part in the depolymerization kettle from top to bottom, a shell pass for transmitting heat medium is formed between the upper tube plate and the lower tube plate, a plurality of groups of heat exchange tubes are welded between the upper tube plate and the lower tube plate, the heat exchange tubes are used for circulating feed liquid and communicated with the inner cavity of the depolymerization kettle at the upper end and the lower end, a central circulating tube is fixedly arranged in the middle of the axes of the upper tube plate and the lower tube plate, and a heat medium outlet and a heat medium inlet are respectively arranged at the upper side and the lower side of the right side of the depolymerization kettle between the upper tube plate and the lower tube plate;
the left side below the depolymerization kettle is provided with a feed inlet, the right side inside the depolymerization kettle is positioned below the heat exchange tube and is provided with a crude lactide gas phase outlet, and the crude lactide gas phase outlet is connected with a depolymerization condenser through a pipeline.
Preferably, the upper end of the central circulating pipe extends to the upper surface of the upper tube plate, and the distance between the lower end of the central circulating pipe and the inner bottom surface of the depolymerization kettle is 1-1.5 times of the diameter of the central circulating pipe.
Preferably, a distributor is arranged at the upper end of the central circulation pipe.
Preferably, the lower surface of the lower tube plate is fixedly provided with a liquid baffle plate positioned at the inner side of the crude lactide gas phase outlet.
Preferably, an insertion pipe is fixedly arranged at the inner side of the gas phase outlet of the crude lactide, and the inlet of the insertion pipe is in an inclined triangular structure with a longer upper part and a shorter lower part.
A depolymerization process for biodegradable materials utilizes a depolymerization kettle for biodegradable materials, and specifically comprises the following steps:
s1, forming an oligomer by lactic acid prepolymerization, adding a catalyst into the oligomer, and conveying the mixed material to a depolymerization kettle through a feed inlet;
s2, starting a driving motor to convey the mixed material positioned at the bottom of the depolymerization kettle to the upper part of the upper tube plate through a spiral propeller along a central circulating tube, uniformly distributing the mixed material to the surface of the upper tube plate through a distributor after the mixed material reaches the upper part of the central circulating tube, enabling the mixed material to flow downwards along a heat exchange tube under the action of gravity, at the moment, inputting a heat medium into the shell passes inside the upper tube plate and the lower tube plate through a heat medium inlet and outputting the heat medium through a heat medium outlet, heating the mixed material through the heat exchange tube, and dripping the heated material liquid to the bottom of the depolymerization kettle for circulation, wherein lactide formed in the operation process descends along the heat exchange tube in a gaseous state;
s3, enabling the gaseous lactide to enter a depolymerization condenser through a crude lactide gas phase outlet for condensation, and conveying the formed crude lactide feed liquid to a next unit.
Preferably, the depolymerization condenser in S3 is vacuum-fed, and the inside of the depolymerization kettle in S2 is in a negative pressure state.
Compared with the prior art, the application provides a depolymerization kettle for biodegradable materials and a process thereof, which have the following beneficial effects:
1. the beneficial effects of the application are as follows: the mode that has adopted spiral lift carries out the transport of feed liquid in depolymerization cauldron inside, compare traditional depolymerization cauldron and adopt the pump to carry, can effectively promote the conveying speed of feed liquid, because traditional gear pump is when facing the oligomer, because the oligomer is a high viscosity material, lead to carrying difficulty, even select the gear pump to carry, also because limit flow's restriction, depolymerization cauldron can not excessively enlarge, single equipment productivity is too little, the user adopts many depolymerization cauldron simultaneous operation generally, equipment investment is high, area is big, but adopt the auger to carry out the transport of feed liquid, the transport flow can be adjusted according to driving motor running speed and the width and the angle that the auger set up, can avoid the problem that the transport limit flow of gear pump is little, the productivity and the efficiency of single equipment have effectively been promoted.
2. The beneficial effects of the application are as follows: the mode that has adopted the screw propulsion ware carries out the transport of feed liquid in depolymerization cauldron inside and forms the inner loop, compares traditional extrinsic cycle depolymerization cauldron, not only can effectually reduce equipment investment, reduces equipment area, can also effectively reduce heat loss, reduces the energy consumption.
Drawings
FIG. 1 is a front view of a depolymerization tank of an embodiment of a depolymerization tank for biodegradable materials in accordance with the present application;
FIG. 2 is a front view of a depolymerization tank with a liquid baffle mounted thereon for one embodiment of a depolymerization tank for biodegradable materials in accordance with the present application;
FIG. 3 is a flowchart of a depolymerization process according to an embodiment of the present application for depolymerizing biodegradable materials;
fig. 4 is a flow chart of a conventional gear pump depolymerization process for one embodiment of a depolymerization process for biodegradable materials according to the present application.
Description of the drawings:
101. a depolymerization kettle; 102. a screw propeller; 103. a driving motor; 104. a central circulation tube; 105. an upper tube sheet; 106. a lower tube sheet; 107 heat exchange tubes; 108. a crude lactide gas phase outlet; 109. a feed inlet; 201. a distributor; 301. a liquid baffle; 302. the tube is inserted.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments.
In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present application and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.
Example 1:
a depolymerization tank for biodegradable materials, comprising: the depolymerization kettle 101, the spiral propeller 102 and the driving motor 103 are arranged below the bottom of the depolymerization kettle 101, the upper end of a main shaft of the driving motor 103 extends into the depolymerization kettle 101 and is detachably connected with the lower end of the spiral propeller 102, and the upper side of the spiral propeller 102 is movably sleeved in the lower end of the central circulating pipe 104;
an upper tube plate 105 and a lower tube plate 106 are respectively and fixedly arranged above and above the depolymerization kettle 101 from top to bottom, a shell pass for transmitting heat medium is formed between the upper tube plate 105 and the lower tube plate 106, a plurality of groups of heat exchange tubes 107 are welded between the upper tube plate 105 and the lower tube plate 106, the heat exchange tubes 107 are used for circulating feed liquid to circulate, the upper end and the lower end of the heat exchange tubes are communicated with the inner cavity of the depolymerization kettle 101, a central circulation tube 104 is fixedly arranged in the center of the axle center of the upper tube plate 105 and the lower tube plate 106, and a heat medium outlet and a heat medium inlet are respectively arranged on the right side of the depolymerization kettle 101 between the upper tube plate 105 and the lower tube plate 106;
a feed inlet 109 is arranged on the left side below the depolymerization kettle 101, a crude lactide gas phase outlet 108 is arranged on the right side inside the depolymerization kettle 101 below the heat exchange tube 107, and the crude lactide gas phase outlet 108 is connected with a depolymerization condenser through a pipeline.
The upper end of the central circulation pipe 104 extends to the upper surface of the upper tube plate 105, and the distance between the lower end of the central circulation pipe 104 and the bottom surface inside the depolymerization kettle 101 is 1 to 1.5 times the diameter of the central circulation pipe 104.
The upper end of the central circulation pipe 104 is provided with a distributor 201.
The lower surface of the lower tube plate 106 is fixedly provided with a liquid baffle 301 positioned on the inner side of the crude lactide gas phase outlet 108.
An insertion pipe 302 is fixedly arranged on the inner side of the crude lactide gas phase outlet 108, and the inlet of the insertion pipe 302 is in an inclined triangle structure with a longer upper part and a shorter lower part.
In this embodiment, after the oligomer produced by the pre-polymerization of lactic acid enters the depolymerization kettle 101 through the feed inlet 109, the oligomer is conveyed upward along the central circulation pipe 104 by the screw propeller 102, the oligomer conveyed to the top end of the central circulation pipe 104 is uniformly dispersed into the heat exchange pipe 107 by the distributor 201 and heated by the heating medium, the heated feed liquid drops to the bottom of the depolymerization kettle 101, and the operation of continuous circulation is performed, so that lactide in the oligomer is separated in a gaseous state, and at the crude lactide gas phase outlet 108, a liquid baffle 301 or an insertion pipe 302 is installed, so that falling liquid can be effectively prevented from entering the inside of the crude lactide gas phase outlet 108.
Example 2:
a depolymerization process for biodegradable materials utilizes a depolymerization kettle for biodegradable materials, and specifically comprises the following steps:
s1, forming an oligomer by lactic acid prepolymerization, adding a catalyst into the oligomer and conveying the mixed material to a depolymerization kettle 101 through a feed inlet 109;
s2, starting a driving motor 103 to convey the mixed material positioned at the bottom of the depolymerization kettle 101 to the upper part of the upper tube plate 105 through a spiral propeller 102 along a central circulating tube 104, uniformly distributing the mixed material to the surface of the upper tube plate 105 through a distributor 201 after the mixed material reaches the upper part of the central circulating tube 104, enabling the mixed material to flow downwards under the action of gravity along a heat exchange tube 107, at the moment, inputting a heat medium into the shell passes inside the upper tube plate 105 and a lower tube plate 106 through a heat medium inlet and outputting the heat medium through a heat medium outlet, heating the mixed material through the heat exchange tube 107, and dripping the heated material liquid to the bottom of the depolymerization kettle 101 for circulation, wherein lactide formed in the operation process descends along the heat exchange tube 107 in a gaseous state;
s3, the gaseous lactide enters a depolymerization condenser through a crude lactide gas phase outlet 108 to be condensed, and crude lactide feed liquid is formed and is conveyed to a next unit.
Further, it is preferable that the depolymerization condenser in S3 is evacuated, and the inside of the depolymerization tank 101 in S2 is in a negative pressure state.
Example 3:
experimental key equipment: the heat exchange area of the depolymerization kettle is 4m 2 The method comprises the steps of carrying out a first treatment on the surface of the The operation pressure of the depolymerization kettle is controlled to be 100Pa (A) absolute pressure; the inlet temperature of the thermal medium is 240 ℃; the outlet temperature of the heating medium is 200 ℃; the maximum flow rate of the gear pump is 55m 3 /h；
The key raw materials for the experiment are as follows: an oligomer (molecular weight: 500 to 4000) formed by a lactic acid prepolymerization reaction; catalysts (tin oxide);
wherein, the experiments with serial numbers 1, 2 and 3 adopt the device in the embodiment 1 and the internal circulation process in the embodiment 2, the specific process flow refers to fig. 3, the experiments with serial numbers 4, 5 and 6 adopt the traditional gear pump external circulation process, the specific process flow refers to fig. 4, and the mixed materials are depolymerized in the appointed time process to prepare lactide; in the experimental process, the preheating process of the starting reaction feed is eliminated, and measurement is carried out after the reaction process is stable;
oligomer molecular weight determination:
the black-bone viscometer measures the characteristic viscosity eta, the solvent is chloroform, the temperature is 25 ℃, and the formula is adoptedCalculation of the viscosity average molecular weight M v Wherein k=2.48×10 -3 (mlg -1 )，a＝0.75。
Lactide purity measurement:
reagents and instrumentation: acetonitrile: chromatographic purity, merck company; chloroform: r. Zhejiang Linan Qingshan chemical reagent plant; absolute ethyl alcohol: r., anhui antui biochemical limited; l-lactide standard: tokyo chemical industry co., japan; phosphoric acid: r., national pharmaceutical group chemical company, inc; high purity water: self-making;
chromatograph: shimadzu LC-10AT; a detector: island body SPD-10ATUV-VIS; chromatographic data processor: shimadzu C-R6A; temperature control box: HCL360, a company of heng-ao technology development limited, tianjin; chromatographic column: ODS2 (5 μm,4.6 mm. Times.150 mm), daLily instruments Co., ltd; mass spectrometer: LCQAdvantage, thermoFinigan, USA;
chromatographic conditions chromatographic column: ODS2 (5 μm,4.6 mm. Times.150 mm); mobile phase: acetonitrile solution prepared by high-purity water; flow rate: 1.0mL/min; sample injection volume: 10. Mu.L; detection wavelength: 210nm; column temperature: 35.0 ℃;
the measuring process comprises the following steps: taking out the crude lactide prepared in the two experimental processes, respectively measuring in parallel for 5 times, and taking an average value to be recorded as the purity of the crude lactide product; the calculation formula is as follows:
c x ％＝K×A x ×100％
wherein: c x L-lactidePurity,%; a is that x Peak area of L-lactide, mv·s, K-correction factor, under this condition k= 2.1067 ×10 -9 g/mL，mV·s。
TABLE 1 crude lactide yield, time and purity for different treatments at the same time
Referring to the data in Table 1 above, the crude lactide produced using the apparatus and process of the present application produced an average of 76.2kg of depolymerized oligomer per hour and an average of 74.5kg of crude lactide per hour over the same period of time; and because of adopting the internal circulation, the material circulation time is shortened, the reaction temperature change is small, and the purity of the crude lactide is higher than that of the traditional process;
example 4:
lactide was prepared by depolymerizing a specified weight of the mixed material using the apparatus of example 1 and the internal circulation process of example 2, as compared to the conventional gear pump external circulation process, with specific process flow referring to fig. 3; in the experimental process, the preheating process of the starting reaction feed is eliminated, and measurement is carried out after the reaction process is stable;
experimental key equipment: the heat exchange area of the depolymerization kettle is 4m 2 The method comprises the steps of carrying out a first treatment on the surface of the The operation pressure in the depolymerization kettle is controlled to be 100Pa (A) absolute pressure; the inlet temperature of the thermal medium is 240 ℃; the outlet temperature of the heating medium is 200 ℃; the maximum flow rate of the gear pump is 55m 3 /h；
The key raw materials for the experiment are as follows: an oligomer (molecular weight: 500 to 4000) formed by a lactic acid prepolymerization reaction; catalysts (tin oxide);
oligomer molecular weight determination: reference is made to the measurement protocol in example 3;
lactide purity measurement: reference is made to the measurement protocol in example 3;
TABLE 2 crude lactide yield and purity for different treatments at the same quality
Wherein, the serial numbers 1, 2 and 3 are produced by adopting the device and the process of the application, and the serial numbers 4, 5 and 6 are produced by adopting the traditional process;
referring to the data in Table 2 above, the crude lactide produced by the apparatus and process of the present application requires only 1.3 hours to process 100kg of oligomer when processing the same quality of oligomer, but the time required for the conventional process is about 2.3 hours, and the processing speed and quality of the apparatus are far superior to those of the conventional process.
The foregoing is only a preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art, who is within the scope of the present application, should make equivalent substitutions or modifications according to the technical scheme of the present application and the inventive concept thereof, and should be covered by the scope of the present application.
Claims (7)
1. A depolymerization tank for biodegradable materials, comprising: the depolymerization kettle (101), the spiral propeller (102) and the driving motor (103) are characterized in that the driving motor (103) is arranged below the bottom of the depolymerization kettle (101), the upper end of a main shaft of the driving motor (103) extends into the depolymerization kettle (101) and is detachably connected with the lower end of the spiral propeller (102), and the upper side of the spiral propeller (102) is movably sleeved in the lower end of the central circulating pipe (104);
an upper tube plate (105) and a lower tube plate (106) are respectively and fixedly arranged in the depolymerization kettle (101) from top to bottom, a shell side for transporting heat medium is formed between the upper tube plate (105) and the lower tube plate (106), a plurality of groups of heat exchange tubes (107) are welded between the upper tube plate (105) and the lower tube plate (106), the heat exchange tubes (107) are used for circulating feed liquid to circulate, the upper end and the lower end are communicated with the inner cavity of the depolymerization kettle (101), a central circulation tube (104) is fixedly arranged in the middle of the axle center of the upper tube plate (105) and the lower tube plate (106), and a heat medium outlet and a heat medium inlet are respectively arranged on the upper side and the lower side of the depolymerization kettle (101) between the upper tube plate (105) and the lower tube plate (106);
the left side below depolymerization cauldron (101) is provided with feed inlet (109), the inside right side of depolymerization cauldron (101) is located heat exchange tube (107) below and is provided with crude lactide gaseous phase export (108), crude lactide gaseous phase export (108) are passed through the pipeline and are linked to each other with depolymerization condenser.
2. A depolymerization tank for biodegradable materials according to claim 1, characterized in that: the upper end of the central circulating pipe (104) extends to the upper surface of the upper tube plate (105), and the distance between the lower end of the central circulating pipe (104) and the inner bottom surface of the depolymerization kettle (101) is 1-1.5 times of the diameter of the central circulating pipe (104).
3. A depolymerization tank for biodegradable materials according to claim 1, characterized in that: the upper end of the central circulation pipe (104) is provided with a distributor (201).
4. A depolymerization tank for biodegradable materials according to claim 1, characterized in that: the lower surface of the lower tube plate (106) is positioned at the inner side of the crude lactide gas phase outlet (108) and is fixedly provided with a liquid baffle plate (301).
5. A depolymerization tank for biodegradable materials according to claim 1, characterized in that: an insertion pipe (302) is fixedly arranged at the inner side of the crude lactide gas phase outlet (108), and the inlet of the insertion pipe (302) is of an inclined triangle structure with long upper part and short lower part.
6. A depolymerization process for biodegradable materials, using a depolymerization tank for biodegradable materials according to claim 1, characterized by the specific steps of:
s1, forming an oligomer by lactic acid prepolymerization, adding a catalyst into the oligomer, and conveying the mixed material to a depolymerization kettle (101) through a feed inlet (109);
s2, starting a driving motor (103) to convey the mixed material positioned at the bottom of the depolymerization kettle (101) to the upper part of the upper tube plate (105) through a spiral propeller (102) along a central circulating tube (104), uniformly distributing the mixed material to the surface of the upper tube plate (105) through a distributor (201) after the mixed material reaches the upper part of the central circulating tube (104), enabling the mixed material to flow downwards under the action of gravity along a heat exchange tube (107), at the moment, inputting a heat medium into shell passes in the upper tube plate (105) and the lower tube plate (106) through a heat medium inlet and outputting the heat medium through a heat medium outlet, heating the mixed material through the heat exchange tube (107), and dripping the heated feed liquid to the bottom of the depolymerization kettle (101) for circulation, wherein lactide formed in the operation process descends along the heat exchange tube (107) in a gaseous state;
s3, enabling the gaseous lactide to enter a depolymerization condenser through a crude lactide gas phase outlet (108) for condensation, and conveying the formed crude lactide feed liquid to a next unit.
7. A depolymerization process for biodegradable materials according to claim 6, characterized in that: and (3) the depolymerization condenser in the step (S3) is vacuumized, and the inside of the depolymerization kettle (101) in the step (S2) is in a negative pressure state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210160402.2A CN116672967A (en) | 2022-02-22 | 2022-02-22 | Depolymerization kettle for biodegradable material and process thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210160402.2A CN116672967A (en) | 2022-02-22 | 2022-02-22 | Depolymerization kettle for biodegradable material and process thereof |
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| Publication Number | Publication Date |
|---|---|
| CN116672967A true CN116672967A (en) | 2023-09-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202210160402.2A Pending CN116672967A (en) | 2022-02-22 | 2022-02-22 | Depolymerization kettle for biodegradable material and process thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117816081A (en) * | 2024-02-28 | 2024-04-05 | 洛阳仁晟石化工程技术有限公司 | High-efficient reation kettle quick temperature regulating mechanism |
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2022
- 2022-02-22 CN CN202210160402.2A patent/CN116672967A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117816081A (en) * | 2024-02-28 | 2024-04-05 | 洛阳仁晟石化工程技术有限公司 | High-efficient reation kettle quick temperature regulating mechanism |
| CN117816081B (en) * | 2024-02-28 | 2024-05-14 | 洛阳仁晟石化工程技术有限公司 | High-efficient reation kettle quick temperature regulating mechanism |
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