CN111662175A - Method and system for preparing MMA (methyl methacrylate) monomer by recycling waste acrylic - Google Patents
Method and system for preparing MMA (methyl methacrylate) monomer by recycling waste acrylic Download PDFInfo
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- CN111662175A CN111662175A CN202010502289.2A CN202010502289A CN111662175A CN 111662175 A CN111662175 A CN 111662175A CN 202010502289 A CN202010502289 A CN 202010502289A CN 111662175 A CN111662175 A CN 111662175A
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- 239000000178 monomer Substances 0.000 title claims abstract description 40
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000002699 waste material Substances 0.000 title claims abstract description 23
- 238000004064 recycling Methods 0.000 title claims abstract description 16
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 title description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 120
- 238000004821 distillation Methods 0.000 claims abstract description 84
- 238000005336 cracking Methods 0.000 claims abstract description 32
- 238000009833 condensation Methods 0.000 claims abstract description 22
- 230000005494 condensation Effects 0.000 claims abstract description 22
- 238000012432 intermediate storage Methods 0.000 claims abstract description 14
- 239000000945 filler Substances 0.000 claims abstract description 13
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000003860 storage Methods 0.000 claims description 51
- 239000007788 liquid Substances 0.000 claims description 30
- 239000000047 product Substances 0.000 claims description 20
- 238000012856 packing Methods 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 14
- 239000012043 crude product Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 239000012535 impurity Substances 0.000 claims description 8
- 238000010992 reflux Methods 0.000 claims description 8
- 238000005057 refrigeration Methods 0.000 claims description 7
- 239000000919 ceramic Substances 0.000 claims description 6
- 239000013049 sediment Substances 0.000 claims description 6
- 229910001220 stainless steel Inorganic materials 0.000 claims description 6
- 239000010935 stainless steel Substances 0.000 claims description 6
- 238000000197 pyrolysis Methods 0.000 claims description 5
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000007710 freezing Methods 0.000 claims description 4
- 230000008014 freezing Effects 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 3
- 239000000446 fuel Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000010922 glass waste Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 20
- 238000010438 heat treatment Methods 0.000 description 12
- 239000008187 granular material Substances 0.000 description 11
- 238000001816 cooling Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 3
- 239000004926 polymethyl methacrylate Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
- C07C67/333—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by isomerisation; by change of size of the carbon skeleton
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention discloses a method and a system for preparing MMA monomers by recycling waste acrylic, and belongs to the technical field of organic glass waste recycling. The method comprises the steps of recovering acrylic acid, crushing, cracking, condensing and distilling to obtain an MMA monomer; the distillation process comprises the following steps: crude MMA obtained by condensation is subjected to crude distillation for 2-4 hours in a crude distillation tower without filler, the distillate is sent to an intermediate storage tank again to be kept stand for 2-5 hours and a water layer is removed, and finally the crude MMA is subjected to rectification for 8-12 hours in a rectification tower filled with filler, wherein the height of the crude distillation tower is 8-10 meters, the height of the rectification tower is 15-20 meters, the crude distillation temperature is 40-70 ℃, and the rectification temperature is 60-65 ℃. The MMA monomer with the purity of 95-97 percent can be obtained, and the whiteness of the acrylic prepared by the monomer is high; meanwhile, taking a 20 cubic rectifying still as an example, 18.3 cubic fractions can be obtained, and the production efficiency is improved (the rough distillation and the rectification can be carried out simultaneously).
Description
Technical Field
The invention belongs to the technical field of organic glass waste recycling, and particularly relates to a method and a system for preparing MMA monomers by recycling waste acrylic.
Background
Acrylic is light, beautiful and tough, is easy to clean, is easy to process, has beautiful color, higher surface hardness and luster, good chemical corrosion resistance, high transparency and stable surface wear resistance close to the physical property of aluminum products, is called as 'plastic queen', and is widely applied to buildings, chemical engineering, industry, advertisements and the like.
The acrylic plate, namely the polymethyl methacrylate plate, is polymerized by methyl methacrylate monomer. One of the existing acrylic plates is called a recycled regeneration plate, which is obtained by utilizing recycled acrylic leftover materials, obtaining a regenerated methyl methacrylate monomer through thermal degradation and then carrying out chemical polymerization reaction. The production method has low input cost and is beneficial to environmental protection.
For example, patent with application number CN201910328678.5 discloses a process flow of an acrylic cracking recovery device, which comprises the following steps:
(1) discharging: and (3) putting the waste acrylic into a hopper, and feeding the waste acrylic into a feeding roller along the hopper.
(2) Conveying materials: the second motor is started, the second motor drives the feeding roller to rotate, and the waste acrylic raw material moves forwards along the external threads of the feeding roller due to the rotation of the feeding roller.
(3) Turning over the roller: the material is prevented by the cooling sleeve from melting without entering the roller, the first motor is started to drive the chain to rotate and the chain wheel to rotate, so that the left roller is rotated to drive the roller to rotate, and the rotating wheel and the auxiliary rotating wheel are arranged outside the left roller to assist in rotation.
(4) Smoke discharging and condensation: the material is cracked into PMMA gas and coke after passing through the roller furnace, and the PMMA gas is introduced into a condensing device through a smoke outlet pipe to be condensed.
For example, patent No. CN 201811558448. X discloses a method for preparing MMA monomer by continuously cracking acrylic, which comprises:
(1) and (3) crushing the acrylic into particles with the particle size less than 20mm to obtain the granular material.
(2) Adding the granular materials into a first heating pipe through a feeding port, conveying the granular materials to a second heating pipe through a screw, and continuously heating the granular materials through a heating device in the conveying process to ensure that the temperature of the granular materials at an outlet of the first heating pipe is 200-300 ℃; and the air mixed in the granular materials is discharged through the first air outlet pipe in the conveying process.
(3) Maintaining the temperature in the second heating pipe to be 500-600 ℃ through a heating device of the second heating pipe, conveying the granular materials obtained in the step (2) by adopting a screw, continuously pyrolyzing the granular materials in the conveying process, and collecting MMA monomer steam obtained by pyrolysis through second air outlet pipes connected to different positions of the second heating pipe; the non-pyrolyzed granules were transported to a vertical gas permeable tube by a screw.
(4) The non-pyrolyzed granular materials enter a third heating pipe through the vertical ventilation pipe, the temperature in the third heating pipe is maintained at 400-500 ℃, and the non-pyrolyzed granular materials are conveyed by a screw rod so as to be pyrolyzed continuously; collecting MMA monomer steam obtained by cracking through third air outlet pipes arranged at different positions of a third heating pipe.
(5) Collecting MMA monomer steam collected in the step (3) and the step (4) into an air outlet header, wherein the second air outlet pipe and the third air outlet pipe are connected into the air outlet header; and carrying out primary condensation through a water-cooling branch pipe connected with the air outlet collecting pipe, and carrying out secondary condensation through a liquid nitrogen cooling mechanism to obtain an MMA monomer finished product.
In the prior art, the method for preparing MMA monomer by recovering waste acrylic acid generally comprises the procedures of crushing, cracking, condensing, distilling and the like, wherein the distillation generally adopts a rectifying tower to carry out rectification at the temperature of 60-65 ℃. The applicant, when using the prior art for the recovery of MMA monomer, found two problems:
(1) the purity of MMA monomer obtained by rectification in the prior art is 93-94%, and the color of the prepared acrylic product is yellowish.
(2) The production efficiency is low, and only 14 cubic fractions can be obtained by taking a 20 cubic rectifying still as an example.
Disclosure of Invention
In order to solve the above problems, embodiments of the present invention provide a method and a system for preparing an MMA monomer by recycling waste acrylic, which can obtain an MMA monomer with a purity of 95-97%, and the whiteness of the acrylic prepared by the monomer is high; meanwhile, taking a 20 cubic rectifying still as an example, 18.3 cubic fractions can be obtained, and the production efficiency is improved (the rough distillation and the rectification can be carried out simultaneously). The technical scheme is as follows:
in one aspect, the embodiment of the invention provides a method for preparing an MMA monomer by recycling waste acrylic acid, which comprises the steps of crushing, cracking, condensing and distilling the recycled acrylic acid to obtain the MMA monomer; the distillation process comprises the following steps: crude MMA obtained by condensation is subjected to crude distillation for 2-4 hours in a crude distillation tower without filler, the distillate is sent to an intermediate storage tank again to be kept stand for 2-5 hours and a water layer is removed, and finally the crude MMA is subjected to rectification for 8-12 hours in a rectification tower filled with filler, wherein the height of the crude distillation tower is 8-10 meters, the height of the rectification tower is 15-20 meters, the crude distillation temperature is 40-70 ℃, and the rectification temperature is 60-65 ℃.
Further, the crude distillation tower in the embodiment of the invention is arranged on a crude distillation kettle, and the volume of the crude distillation kettle is 5-7 cubic meters; the rectifying tower is arranged on a rectifying still, and the volume of the rectifying still is 15-20 cubic.
Wherein, the condensation process in the embodiment of the invention is as follows: and (3) carrying out primary condensation on the pyrolysis gas by using a primary tube array condenser 1, separating insoluble impurities by using a settling tank 2, carrying out secondary condensation by using a secondary tube array condenser 3, carrying out tertiary condensation by using a jacket condenser to obtain an MMA crude product, and filtering the insoluble impurities by using a pipeline filter 4 to obtain the MMA crude product.
Preferably, the condensation process in the embodiment of the present invention further includes: the method comprises the following steps that exhaust gas of a storage tank for storing crude MMA is output to a vacuum tank through a vertical condenser vertically arranged on the storage tank, the vacuum tank is output to a water tank in two ways, the exhaust gas is output to one way with a Roots blower when power is off, otherwise, the exhaust gas is output to one way with a water ring vacuum pump, the two ways are both introduced into liquid in the water tank, and gas output by the water tank sequentially passes through a primary oil-water separator, a heat exchange condenser and a secondary oil-water separator and then is sent to a cracking furnace to serve as fuel; the Roots blower is powered by the generator; the heat exchange condenser is positioned in a refrigeration house with the freezing temperature of 10 ℃ or below, the refrigeration house is used as a heat exchange medium, and the output condensate is also an MMA crude product; the water tank supplies water for the water ring vacuum pump, is of a closed box structure, the inner lower part of the water tank is liquid, the inner upper part of the water tank is gas, and the liquid in the water tank is replaced according to a preset requirement.
Further, the crude distillation residual liquid of the crude distillation tower in the embodiment of the invention is sent to a cracking process, and the rectification residual liquid of the rectification tower is sent to the crude distillation tower for crude distillation.
The packing of the rectifying tower in the embodiment of the invention is stainless steel packing or ceramic packing, and the reflux ratio during rectification is 1:1-1: 4.
On the other hand, the embodiment of the invention provides a system for preparing MMA monomers by recycling waste acrylic acid, which comprises a cracking furnace, a condensing device, a storage tank, a rough distillation device and a rectification device, wherein the cracking furnace, the condensing device and the storage tank are sequentially connected through a pipeline; the rectification device comprises a rectification tower filled with filler, a rectification condenser, a rectification gas-water separator, a rectification buffer tank, a finished product condenser and a finished product storage tank, wherein a rectification kettle is arranged at the bottom of the rectification tower, the rectification condenser, the rectification gas-water separator and the rectification buffer tank are sequentially connected through a pipeline, the rectification buffer tank is output in two ways, one way is output to a reflux port of the rectification tower through the pipeline, and the other way is output to an inlet of the finished product condenser through the pipeline; the outlet of the finished product condenser is connected with a finished product storage tank through a pipeline; the device comprises a coarse distillation tower, a coarse distillation condenser, a coarse distillation gas-water separator, a coarse distillation buffer tank and an intermediate storage tank which are sequentially connected through pipelines and do not have filler, wherein a coarse distillation kettle is arranged at the bottom of the coarse distillation tower, the storage tank is connected with the coarse distillation kettle through a pipeline, and an oil phase outlet of the intermediate storage tank is connected with the rectification kettle through a pipeline.
The height of the crude distillation tower in the embodiment of the invention is 8-10 m, the height of the rectification tower is 15-20 m, the volume of the crude distillation kettle is 5-7 cubic, the volume of the rectification kettle is 15-20 cubic, and the packing of the rectification tower is stainless steel packing or ceramic packing.
The condensing device comprises a pipeline filter 4, and a primary tube array condenser 1, a settling tank 2, a secondary tube array condenser 3 and a jacket condenser which are sequentially connected through a pipeline, wherein a sediment outlet of the settling tank 2 is connected with a material storage tank through a pipeline with a first valve 6 and the pipeline filter 4, an inlet of the primary tube array condenser 1 is connected with a cracking furnace through a pipeline, and an outlet of the jacket condenser is connected with the material storage tank through a pipeline.
Preferably, the storage tank in the embodiment of the invention is a horizontal storage tank; the condensing device also comprises a vertical condenser, a vacuum tank, a water ring vacuum pump, a water tank for supplying water to the water ring vacuum pump, a primary oil-water separator, a secondary oil-water separator, a cold storage, a Roots blower, a generator for supplying power to the Roots blower and a heat exchange condenser in the cold storage; the water tank is of a closed tank structure, the inner lower part of the water tank is liquid, and the inner upper part of the water tank is gas; the vertical condenser is arranged on an exhaust port of the material storage tank along the vertical direction, an outlet at the top end of the vertical condenser is connected with an air inlet of the vacuum tank through a pipeline, an air outlet of the vacuum tank is output into liquid of the water tank in two ways and is gated through a valve, a water ring vacuum pump is arranged on one way, and a Roots blower is arranged on the other way; the gas outlet on the upper part of the water tank, the primary oil-water separator, the heat exchange condenser, the secondary oil-water separator and the combustion chamber of the cracking furnace are sequentially connected through pipelines, and the heat exchange condenser takes a refrigeration house as a heat exchange medium and is provided with a condensate outlet at the bottom.
The technical scheme provided by the embodiment of the invention has the following beneficial effects: the embodiment of the invention provides a method and a system for preparing an MMA monomer by recycling waste acrylic, the MMA monomer with the purity of 95-97% can be obtained, and the whiteness of the acrylic prepared by the monomer is high; meanwhile, taking a 20 cubic rectifying still as an example, 18.3 cubic fractions can be obtained, and the production efficiency is improved (the rough distillation and the rectification can be carried out simultaneously).
Drawings
FIG. 1 is a schematic block diagram of a system for preparing MMA monomer by recycling waste acrylic according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a condensing unit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the construction of the settling tank and pipe filter combination.
In the figure: the system comprises a primary tubular condenser 1, a settling tank 2, a secondary tubular condenser 3, a pipeline filter 4, a blow-off pipe 5, a first valve 6, a three-way pipe 7, a blow-off valve 8 and a second valve 9.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
Example 1
Referring to fig. 1, example 1 provides a system for preparing MMA monomer by recycling waste acrylic, which comprises a cracking furnace, a condensing device, a material storage tank, a rough distillation device, a rectification device and the like; wherein, the cracking furnace cracks the crushed acrylic at 350 ℃; condensing the cracked tail gas by using a condensing device to obtain an MMA crude product; the cracking furnace, the condensing device and the storage tank are connected in sequence through pipelines. The rectifying device comprises a rectifying tower filled with filler, a rectifying condenser, a rectifying gas-water separator, a rectifying buffer tank, a finished product condenser, a finished product storage tank and the like, wherein a rectifying kettle is arranged at the bottom of the rectifying tower, the rectifying condenser, the rectifying gas-water separator and the rectifying buffer tank are sequentially connected through a pipeline, the rectifying buffer tank is output in two ways (provided with a pump and a valve group, and the reflux ratio is controlled through the valve group), one way is output to a reflux port of the rectifying tower through the pipeline as reflux, and the other way is output to an inlet of the finished product condenser through the pipeline to output a finished product. The outlet of the finished product condenser is connected with a finished product storage tank through a pipeline. The rough distillation device comprises a rough distillation tower, a rough distillation condenser, a rough distillation gas-water separator, a rough distillation buffer tank, an intermediate storage tank (playing a role of intermediate storage and being capable of separating water), and the like which are connected in sequence through pipelines, wherein the rough distillation tower is provided with a rough distillation kettle at the bottom, the storage tank is connected with the rough distillation kettle through a pipeline, and an oil phase outlet (water in the intermediate storage tank is a lower layer and is discharged, water can be discharged firstly and then the oil phase is output) of the intermediate storage tank is connected with the rectification kettle through a pipeline. The rectification condenser, the rectification gas-water separator, the rectification buffer tank, the rough rectification condenser, the rough rectification gas-water separator and the rough rectification buffer tank are all of conventional structures, and the rough rectification gas-water separator, the intermediate storage tank, the finished product storage tank and the like are connected with a vacuum system through pipelines to be evacuated.
Wherein, the height of the rough distillation tower is 8-10 meters, the height of the rectification tower is 15-20 meters, the volume of the rough distillation kettle is 5-7 cubic meters, the volume of the rectification kettle is 15-20 cubic meters, and the packing of the rectification tower is stainless steel packing or ceramic packing and the like (which are conventional packing of the rectification tower).
Referring to fig. 2 and 3, the condensing device in the embodiment of the present invention includes a pipe filter 4, and a primary pipe array condenser 1, a settling tank 2, a secondary pipe array condenser 3, a jacket condenser, and the like, which are sequentially connected through a pipeline, wherein a sediment outlet (bottom) of the settling tank 2 is connected with a storage tank through a pipeline with a first valve 6 and the pipe filter 4, an inlet of the primary pipe array condenser 1 is connected with a cracking furnace through a pipeline, and an outlet of the jacket condenser is connected with the storage tank through a pipeline. The primary tubular condenser 1, the secondary tubular condenser 3 and the jacket condenser in the embodiment all adopt cooling water for condensation, and preferably perform countercurrent heat exchange. Further, the pipe diameter (outer diameter, and then, correspondingly, the liquid passing section is larger) of the primary tubulation condenser 1 is larger than that of the secondary tubulation condenser 3, the pipe diameter of the jacket condenser 5 is smaller, and the liquid passing section is smaller than that of the tubulation condenser 7, so as to adapt to the state and flow change of the cracked gas. Wherein, in this embodiment after once cooling, just will not dissolve impurity separation when pyrolysis gas is still the air water mixture, not only have better separation effect (the temperature is high, and liquid viscosity is low, and liquid is few, and settling rate is fast), still reduce follow-up condenser scale deposit. Furthermore, the height from the primary tubular condenser 1 to the ground (higher than that of the cracking furnace) is more than the height from the secondary tubular condenser 3 to the ground is more than the height from the jacket condenser to the ground (higher than that of the storage tank). Specifically, the primary shell and tube condenser 1, the secondary shell and tube condenser 3 and the jacket condenser are all horizontally arranged and arranged side by side.
Referring to fig. 3, the settling tank 2 in the embodiment of the present invention has a rectangular tank structure, and has a partition and/or a baffle (conventional structure for increasing residence time and guiding solid impurities to the bottom, and the detailed description is omitted in this embodiment) inside, and has a tapered bottom (large top and small bottom for discharging sediments). The outlet of the primary tubular condenser 1 and the inlet of the secondary tubular condenser 3 are connected to two side surfaces (two adjacent and vertical side surfaces in this embodiment) of the upper portion of the settling tank 2 through pipes, respectively. The bottom end of the cone-shaped structure is a sediment outlet. A blow-off pipe 5 (with suspended bottom end) is arranged on the sediment outlet of the settling tank 2 along the vertical direction, a first valve 6 is arranged on the blow-off pipe 5, and a three-way pipe 7 (T-shaped structure) is arranged at the lower end of the blow-off pipe. The feed inlet of the three-way pipe 7 is vertically arranged and is connected with the bottom end of the sewage discharge pipe 5. A discharge port of the three-way pipe 7 is vertically arranged, a drain valve 8 is arranged on the three-way pipe, and a waste receiving barrel (a cover is arranged on the three-way pipe, is opened during material receiving, is positioned on the ground, can move and has a small volume of 5-20L generally) is arranged under the three-way pipe. The other discharge hole of the three-way pipe 7 is horizontally arranged and is connected with the feed hole of the pipeline filter 4. And a second valve 9 is arranged on a pipeline conveyed by the discharge hole of the pipeline filter 4.
Preferably, referring to fig. 2, the storage tank in the embodiment of the present invention is a horizontal storage tank, the condensing device further includes a vertical condenser (which is disposed on the exhaust port at the top of the storage tank along the vertical direction and may be a shell-and-tube (preferred) or jacket-type condenser), a vacuum tank, a water ring vacuum pump, a water tank for supplying water to the water ring vacuum pump (which is a conventional structure configured for the water ring vacuum pump and supplies circulating water, and in this embodiment, the present invention may also function as a back suction prevention function), a primary oil-water separator (which separates oil from water and prevents back suction and back fire), a secondary oil-water separator (which separates oil from water and prevents back suction and back fire), a cold storage (which has a freezing temperature of-10 ℃ or below and can keep a low temperature for a long time after power failure), a roots blower, a generator (electrically connected to the roots blower) for supplying power, and a heat, for example, a vertical coil condenser without a heat exchange jacket or without cooling water introduced into the heat exchange jacket is provided with a condensed water outlet at the bottom thereof (which can be output to a small storage tank (storage plus liquid seal) and then sent to a storage tank), and the like. Wherein, the water tank is a closed tank structure, the inner lower part of the water tank is liquid, the inner upper part of the water tank is gas, and the water tank is preferably of a corrosion-resistant structure. The vertical condenser is arranged on an exhaust port of the material storage tank along the vertical direction, an outlet (used for exhausting and an inlet used for air intake and condensate backflow) at the top end of the vertical condenser is connected with an air inlet of the vacuum tank through a pipeline, an air outlet of the vacuum tank is divided into two paths to be output into liquid of the water tank (respectively vertically and downwards penetrates through the top of the water tank to the position below the liquid level through two pipelines) and is gated through a valve, a water ring vacuum pump (normally gated) is arranged on one path, and a Roots fan (gated during power failure and generator working) is arranged on the other. The gas outlet (above the liquid level) at the upper part of the water tank, the primary oil-water separator, the heat exchange condenser, the secondary oil-water separator and the combustion chamber of the cracking furnace are sequentially connected through pipelines, the heat exchange condenser takes a refrigeration house as a heat exchange medium, and a condensate outlet (condensate is sent to the storage tank) is arranged at the bottom of the heat exchange condenser.
Wherein, vacuum tank, water tank and water ring vacuum pump all locate subaerially, and roots's fan and primary oil water separator are higher than the water tank (prevent suck-back, through corresponding support). The lower part of the water tank is connected with a water replenishing pump (for replenishing water) and a waste water storage tank (for discharging waste and recovering oil phase according to requirements) through pipelines and is used for replacing circulating water at regular time or when the water quality is obviously not practical, the circulating water is replaced once in 4-12 hours usually, and the water tank is a rectangular closed box body. In particular, the power of the roots blower is much less than that of the water ring vacuum pump, which is used only to deliver uncondensed gases. Wherein the power of the water ring vacuum pump is 8-15kw, and specifically can be 10 kw; the power of the Roots blower is 1.0-2.5kw, and specifically may be 1.5 kw.
Further, a residual liquid outlet of the crude distillation kettle is connected with the cracking furnace through a pipeline, and a residual liquid outlet of the rectification kettle is connected with the crude distillation kettle through a pipeline.
In the present embodiment, a pump, a valve, a flowmeter, and/or the like are provided in the pipeline between the structures as needed. In this embodiment, "first" and "second" only have a distinguishing function, and have no other special meaning.
Example 2
Example 2 provides a method for preparing MMA monomer from recycled waste acrylic acid, which adopts the preparation system disclosed in example 1, and comprises the steps of crushing, cracking, condensing and distilling the recycled acrylic acid to obtain MMA monomer. The pulverization and cracking were exactly the same as in the prior art, and the insoluble matter was removed in this example during the condensation. Wherein the distillation process comprises the following steps: crude MMA obtained by condensation is subjected to crude distillation for 2-4 hours in a crude distillation tower without filler, the distillate is sent to an intermediate storage tank again to be kept stand for 2-5 hours and a water layer is removed, and finally the crude MMA is subjected to rectification for 8-12 hours in a rectification tower filled with filler, wherein the height of the crude distillation tower is 8-10 meters, the height of the rectification tower is 15-20 meters, the crude distillation temperature is 40-70 ℃ (accurate control is not required, the operation is easy), and the rectification temperature is 60-65 ℃.
Furthermore, the crude distillation tower in the embodiment of the invention is arranged on a crude distillation kettle, and the volume of the crude distillation kettle is 5-7 cubic meters; the rectifying tower is arranged on the rectifying still, and the volume of the rectifying still is 15-20 cubic. In this example, the fraction obtained by the 3-time rough distillation was sent to an intermediate storage tank to be allowed to stand and delaminate, and then sent to a rectifying column. Rectification and rough distillation are carried out simultaneously without mutual interference.
Wherein, the condensation process in the embodiment of the invention is as follows: and (3) carrying out primary condensation on the pyrolysis gas by using a primary tube array condenser 1, separating insoluble impurities by using a settling tank 2, carrying out secondary condensation by using a secondary tube array condenser 3, carrying out tertiary condensation by using a jacket condenser to obtain an MMA crude product, and filtering the insoluble impurities by using a pipeline filter 4 to obtain the MMA crude product.
Preferably, the condensation process in the embodiment of the present invention further includes: the exhaust of a storage tank for storing MMA crude products is output to a vacuum tank through a vertical condenser vertically arranged on the storage tank, the vacuum tank is output to a water tank in two ways, the exhaust is output to one way with a Roots blower when power is off, otherwise, the exhaust is output to one way with a water ring vacuum pump, the two ways are all introduced into liquid of the water tank, and gas output by the water tank sequentially passes through a primary oil-water separator, a heat exchange condenser and a secondary oil-water separator and then is sent to a cracking furnace to serve as fuel (a combustion chamber). The Roots blower is powered by a generator. The heat exchange condenser is positioned in a cold storage with the freezing temperature of 10 ℃ or below, the cold storage is used as a heat exchange medium, and the output condensate is also an MMA crude product. The water tank is used for supplying water for the water ring vacuum pump, the water tank is of a closed box body structure, the inner lower part of the water tank is liquid, the inner upper part of the water tank is gas, and the liquid in the water tank is replaced according to a preset requirement (preset time or when the water quality does not meet the requirement).
Further, the crude distillation residual liquid of the crude distillation tower in the embodiment of the invention is sent to a cracking process, and the rectification residual liquid of the rectification tower is sent to the crude distillation tower for crude distillation.
The packing of the rectifying tower in the embodiment of the invention is stainless steel packing or ceramic packing and the like, and the reflux ratio during rectification is 1:1-1: 4.
The ratio of MMA monomers obtained in the prior art to that obtained in the prior art is shown in Table 1 (in terms of 20 cubic meters of the volume of the rectifying still):
TABLE 1
| Prior Art | The present technology | |
| Purity of monomer | 93-94% | 95-97% |
| Fraction of rectification | 13.7-14.2 cubic | 18.0-18.5 cubic |
| The obtained acrylic | Yellow color | White colour (Bai) |
During crude distillation, the residual distillation liquid is about 1 cubic meter (calculated by 6 cubic meters of the volume of a crude distillation kettle), and can be sent to a cracking furnace for cracking (basically no moisture); based on 24 cubic MMA crude product, the technology can obtain about 18.0-18.5 cubic MMA monomer, while the prior art can obtain about 16.45-17.0 cubic MMA monomer, i.e. the patent also has higher yield.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A method for preparing MMA monomers by recycling waste acrylic acid comprises the steps of crushing, cracking, condensing and distilling the recycled acrylic acid to obtain MMA monomers; characterized in that the distillation process comprises: crude MMA obtained by condensation is subjected to crude distillation for 2-4 hours in a crude distillation tower without filler, the distillate is sent to an intermediate storage tank again to be kept stand for 2-5 hours and a water layer is removed, and finally the crude MMA is subjected to rectification for 8-12 hours in a rectification tower filled with filler, wherein the height of the crude distillation tower is 8-10 meters, the height of the rectification tower is 15-20 meters, the crude distillation temperature is 40-70 ℃, and the rectification temperature is 60-65 ℃.
2. The method for preparing MMA monomer according to the recycled waste acrylic acid, according to claim 1, wherein the crude distillation column is arranged on a crude distillation still, and the volume of the crude distillation still is 5-7 cubic degrees; the rectifying tower is arranged on a rectifying still, and the volume of the rectifying still is 15-20 cubic.
3. The method for preparing MMA according to claim 1, wherein the condensing process comprises: and (3) carrying out primary condensation on the pyrolysis gas through a primary tube array condenser (1), separating insoluble impurities by using a settling tank (1), carrying out secondary condensation through a secondary tube array condenser (3) and carrying out tertiary condensation through a jacket condenser to obtain an MMA crude product, and filtering the insoluble impurities through a pipeline filter (4) to obtain the MMA crude product.
4. The method for preparing MMA according to claim 3, wherein the condensing process further comprises: the method comprises the following steps that exhaust gas of a storage tank for storing crude MMA is output to a vacuum tank through a vertical condenser vertically arranged on the storage tank, the vacuum tank is output to a water tank in two ways, the exhaust gas is output to one way with a Roots blower when power is off, otherwise, the exhaust gas is output to one way with a water ring vacuum pump, the two ways are both introduced into liquid in the water tank, and gas output by the water tank sequentially passes through a primary oil-water separator, a heat exchange condenser and a secondary oil-water separator and then is sent to a cracking furnace to serve as fuel; the Roots blower is powered by the generator; the heat exchange condenser is positioned in a refrigeration house with the freezing temperature of 10 ℃ or below, the refrigeration house is used as a heat exchange medium, and the output condensate is also an MMA crude product; the water tank supplies water for the water ring vacuum pump, is of a closed box structure, the inner lower part of the water tank is liquid, the inner upper part of the water tank is gas, and the liquid in the water tank is replaced according to a preset requirement.
5. The method for preparing MMA monomer according to the recycled waste acrylic acid as claimed in claim 1, wherein the crude distillation raffinate of the crude distillation tower is sent to the cracking process, and the rectification raffinate of the rectification tower is sent to the crude distillation tower for crude distillation.
6. The method for preparing MMA monomer according to claim 1, wherein the packing of the rectification column is stainless steel packing or ceramic packing, and the reflux ratio during rectification is 1:1-1: 4.
7. A system for preparing MMA monomers by recycling waste acrylic comprises a cracking furnace, a condensing device, a storage tank and a rectifying device, wherein the cracking furnace, the condensing device and the storage tank are sequentially connected through a pipeline; the rectification device comprises a rectification tower filled with filler, a rectification condenser, a rectification gas-water separator, a rectification buffer tank, a finished product condenser and a finished product storage tank, wherein a rectification kettle is arranged at the bottom of the rectification tower, the rectification condenser, the rectification gas-water separator and the rectification buffer tank are sequentially connected through a pipeline, the rectification buffer tank is output in two ways, one way is output to a reflux port of the rectification tower through the pipeline, and the other way is output to an inlet of the finished product condenser through the pipeline; the outlet of the finished product condenser is connected with a finished product storage tank through a pipeline; the system is characterized by further comprising a rough distillation device, wherein the rough distillation device comprises a rough distillation tower, a rough distillation condenser, a rough distillation gas-water separator, a rough distillation buffer tank and an intermediate storage tank which are sequentially connected through pipelines and do not have filler, a rough distillation kettle is arranged at the bottom of the rough distillation tower, the storage tank is connected with the rough distillation kettle through a pipeline, and an oil phase outlet of the intermediate storage tank is connected with the rectification kettle through a pipeline.
8. The system for preparing MMA according to claim 7, wherein the height of the crude distillation column is 8-10 m, the height of the rectification column is 15-20 m, the volume of the crude distillation still is 5-7 cubic, the volume of the rectification still is 15-20 cubic, and the packing of the rectification column is stainless steel packing or ceramic packing.
9. The system for recycling waste acrylic acid to prepare MMA monomers according to claim 7, wherein the condensing device comprises a pipeline filter (4), and a primary tubular condenser (1), a settling tank (2), a secondary tubular condenser (3) and a jacket condenser which are sequentially connected through a pipeline, a sediment outlet of the settling tank (2) is connected with a storage tank through a pipeline with a first valve (6) and the pipeline filter (4), an inlet of the primary tubular condenser (1) is connected with the cracking furnace through a pipeline, and an outlet of the jacket condenser is connected with the storage tank through a pipeline.
10. The system for recycling waste acrylic to prepare MMA monomer according to claim 9, wherein the storage tank is a horizontal storage tank;
the condensing device also comprises a vertical condenser, a vacuum tank, a water ring vacuum pump, a water tank for supplying water to the water ring vacuum pump, a primary oil-water separator, a secondary oil-water separator, a cold storage, a Roots blower, a generator for supplying power to the Roots blower and a heat exchange condenser in the cold storage;
the water tank is of a closed tank structure, the inner lower part of the water tank is liquid, and the inner upper part of the water tank is gas;
the vertical condenser is arranged on an exhaust port of the material storage tank along the vertical direction, an outlet at the top end of the vertical condenser is connected with an air inlet of the vacuum tank through a pipeline, an air outlet of the vacuum tank is output into liquid of the water tank in two ways and is gated through a valve, a water ring vacuum pump is arranged on one way, and a Roots blower is arranged on the other way; the gas outlet on the upper part of the water tank, the primary oil-water separator, the heat exchange condenser, the secondary oil-water separator and the combustion chamber of the cracking furnace are sequentially connected through pipelines, and the heat exchange condenser takes a refrigeration house as a heat exchange medium and is provided with a condensate outlet at the bottom.
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