CN115317953A

CN115317953A - Method for recovering organic matters through continuous extraction and pyrolysis of supercritical fluid

Info

Publication number: CN115317953A
Application number: CN202110503321.3A
Authority: CN
Inventors: 卢序
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-10
Filing date: 2021-05-10
Publication date: 2022-11-11

Abstract

The invention discloses a method for continuously extracting and pyrolyzing supercritical fluid to recover organic matters, which comprises the following steps: first, an article to be recovered is pulverized and immersed in a solvent. Soaking for a period of time, softening the recovered material, further stirring, and pulverizing. Then, the material to be recovered and the solvent are injected into the tubular reactor through a high-pressure pump, and then the material to be recovered insoluble in the solvent is conveyed from one end of the tubular reactor to the other end of the tubular reactor through a spiral feeding device. The tubular reactor has a temperature gradient, the injection end of the material to be recovered is a low-temperature region, and the discharge end of the material which can not be dissolved is a high-temperature region. The recoverable organic matter dissolved by the liquid solvent in the low-temperature area or dissolved by the supercritical fluid solvent in the high-temperature area and pyrolyzed is discharged from the low-temperature area of the tubular reactor in a liquid form along with the solvent. And finally, separating and recovering the organic matters in the discharged solvent.

Description

Method for recovering organic matters through continuous extraction and pyrolysis of supercritical fluid

Technical Field

The invention relates to a method for continuously extracting and pyrolyzing supercritical fluid to recover organic matters. The method is mainly used for extracting and pyrolyzing to collect crude oil in oil sand, oil shale and oil sludge, recovering organic matters from waste tires, waste plastics and waste silica gel, and dissolving resin in an inorganic fiber composite material to recover inorganic fibers.

Background

Currently, the main commercial process for the treatment and recovery of organic-containing waste is conventional thermal cracking. However, the organic matter is decomposed by solvent and then is subsequently recovered, which has become a very promising development direction in the organic matter recovery field. The high-temperature supercritical fluid solvent extraction has the potential of recovering high-molecular organic matter synthetic monomers, and can reduce carbon emission compared with simple thermal cracking.

Solvent extraction for recovering crude oil from oil sand, oil shale and oil sludge is a conventional method for recovering crude oil. On the other hand, solvents such as toluene, xylene, methylene chloride and the like can be used for swelling waste tires and waste plastics and then recycling them. However, there are many problems with solvent dissolution recovery at present. For example, extraction or dissolution below the boiling point of the solvent has the greatest problem of insufficient solubility of the high molecular organic substance in crude oil or the high molecular organic compound highly crosslinked, in addition to the disadvantage of using a large amount of solvent. In addition, if the extract contains bound water and free water, the extract is difficult to be miscible with the organic solvent under normal pressure conditions, which affects the dissolution efficiency. There are corresponding solutions to the above problems, such as increasing the temperature to increase solubility; high-temperature cracking, namely depolymerizing or pyrolyzing high-molecular organic matters into organic matters with lower molecular weight, and then dissolving the organic matters by a solvent; increasing the solubility of water in the extractant; dissolving with mixed solvent, etc. Supercritical fluid extraction can simultaneously achieve the above solutions.

The recovery of organic materials by supercritical fluid extraction has been of long interest. People began to focus on the research of extracting the resource of the famous shale oil by using supercritical toluene and supercritical water as early as 80 years in the 20 th century. With the popularization of carbon dioxide supercritical equipment, methods for recovering organic matters by supercritical carbon dioxide extraction have also been widely studied by the academia. In recent years, supercritical butanol and acetone are found to have good depolymerization effect on thermosetting epoxy resin of carbon fiber and glass fiber composite materials, so that the inorganic fiber materials are efficiently recycled.

Based on the results of past research, the high-temperature supercritical fluid has high solubility and pyrolysis effect on crude oil in oil sand, oil shale and oil sludge, and therefore has high extraction rate. The supercritical fluid also has good depolymerization effect on waste tires, waste plastics, waste resins and so on, thereby recycling organic matters and corresponding inorganic materials. Conventional pyrolysis schemes tend to yield only fuel oils. Different from the thermal cracking scheme, organic materials with higher added values can be obtained after the organic materials extracted and recovered by the supercritical fluid are rectified, the recovery temperature is lower, the heating is more uniform, and the recovery rate is higher.

Although supercritical fluid dissolution efficiency is high at present, continuous dissolution is often impossible. This results in overall system inefficiency. In addition, when the high-temperature supercritical fluid degrades organic substances, monomers cannot be discharged in time, so that dimers and even higher polymers are generated, and the thermal cracking efficiency is reduced.

Disclosure of Invention

The invention aims to provide a method for continuously extracting and pyrolyzing supercritical fluid to recover organic matters, which has simple operation process and can adopt supercritical solvent to efficiently and quickly extract and pyrolyze to recover the organic matters.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

firstly, the solid matter to be recovered containing organic matters is crushed and then is fully mixed with the solvent by stirring, and a certain temperature is kept. The main purpose of this step is to dissolve and swell part of the organic matter in the solid matter to be recovered by the solvent and to further break up the solid matter to be recovered by stirring. The temperature is maintained to increase the efficiency of dissolution and swelling as much as possible.

The solid substances to be recovered containing organic matters comprise oil sand, oil shale and oil sludge; polyethylene plastics, polypropylene plastics, polyvinyl chloride plastics, polystyrene plastics, acrylonitrile-butadiene-styrene copolymer plastics, polymethacrylate plastics, ethylene-vinyl acetate copolymer plastics, polyethylene terephthalate plastics, polybutylene terephthalate plastics, polyamide plastics, polycarbonate plastics, polyformaldehyde plastics, polyphenyl ether plastics and polyurethane plastics; compounding an inorganic fiber material with an epoxy resin and phenolic resin matrix; tires, silicone rubber.

The solvent comprises one or more of dichloromethane, trichloromethane, tetrachloromethane, dioxane, aniline, dipropylamine, diisopropylamine, cyclohexanone, cyclohexane, benzene, benzaldehyde, toluene, xylene, n-hexane, n-pentane, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, n-propanol, isopropanol, n-butanol, acetonitrile, water and carbon dioxide. Wherein the organic solvent mainly acts as a solvent. Such as aromatic compounds, carbon dioxide and water, are relatively stable at high temperatures and can be used to dissolve and pyrolyze organic materials.

The temperature to be maintained for the stirring and mixing is between room temperature and the atmospheric boiling point of the solvent. The stirring step was allowed to be at atmospheric pressure.

The solvent may contain a catalyst including alumina, molecular sieves, ammonium fluoride, tetrabutylammonium fluoride.

And secondly, continuously injecting the mixture uniformly stirred in the previous step into a tubular reactor with certain pressure by a high-pressure pump.

The pressure in the tubular reactor is above the critical pressure of the solvent. When the solvent is a single solvent, the critical pressure is preferably determined and can be determined by reference to literature. When the solvent is a mixture of a plurality of solvents, the solvent can be determined by experimental determination, or can be determined by calculation by an empirical formula. The formula may be calculated by referring to The formula in chapter five, fifth edition of The Properties of Gases And Liquids.

And thirdly, one end of the tubular reactor, which is filled with the mixture, is a low-temperature area, insoluble substances in the mixture are discharged from the other end of the tubular reactor, and the insoluble substances discharge end is a high-temperature area and is provided with a heating device and high-temperature and high-pressure solvent injection.

The temperature of the high-temperature region and the temperature of the injected solvent are both higher than the critical temperature of the solvent. As with the critical pressure, the critical temperature is preferably determined when the solvent is a single solvent, and can be determined by reference to literature. When the solvent is a mixture of a plurality of solvents, the critical temperature can be determined by experimental determination, or can be determined by calculation according to an empirical formula. The formula may be calculated by referring to The formula in chapter five, fifth edition of The Properties of Gases And Liquids.

It should be noted that generally 200 ℃ is preceded by the volatilization of water and the dissolution of part of the organic matter in the solid to be recovered. After 300 ℃, depolymerization and decomposition reactions mainly occur, and carbonization and significant cracking of organic solvents occur above 400 ℃. Typically temperatures up to 550 c are sufficient to dissolve most of the organics beyond the coke. Therefore, the heating needs to be determined according to the organic matter to be recovered. The temperature of the supercritical fluid cracking organic matter is in a range of 350-400 ℃ in general, and is generally not more than 550 ℃ and the limit is 650 ℃.

The high-temperature high-pressure solvent injection is used for extracting and pyrolyzing residual solid matters in a high-temperature area by using a solvent with lower concentration of recovered organic matters, so that the concentration gradient of the recovered organic matters in the solvent is gradually increased from the high-temperature area to a low-temperature area, and the requirement of the batch solvent extraction process on the parameter of the solvent-material ratio is eliminated.

And fourthly, conveying the solid substances to be recovered to a high-temperature area at the other end of the tubular reactor from a low-temperature area at one end of the tubular reactor by a spiral feeding device in the tubular reactor.

Due to the presence of the high temperature zone and the low temperature zone, a temperature gradient exists in the tubular reactor. The direction of the spiral feeding is consistent with the direction of the temperature rise, and the speed of the spiral feeding determines the heating rate of the solid substances to be recovered. The spiral feeding device can be used for conveying solid substances to be recovered and stirring, so that the radial convection heat exchange effect of the tubular reactor is increased, and the axial convection effect of the tubular reactor is reduced.

And fifthly, gradually dissolving or pyrolyzing organic matters contained in the solid by the solvent in the process of conveying the solid to be recovered from the low-temperature area to the high-temperature area.

And sixthly, discharging the liquid solvent containing recoverable organic matters in the tubular reactor out of the tubular reactor from a liquid outlet of the low-temperature area of the tubular reactor, and conveying the insoluble matters to a discharge outlet to be discharged out of the tubular reactor.

An included angle of more than 15 degrees is formed between the local area of the tubular reactor and the horizontal plane, and the low-temperature area is positioned at a lower altitude, so that a liquid seal is formed between the liquid state and the supercritical state interface of the solvent in the tubular reactor, and the liquid seal interface ensures that the supercritical fluid cannot be discharged from a liquid outlet of the low-temperature area.

Since the solvent is mainly discharged from the low-temperature region and the solvent density of the low-temperature region is higher than that of the high-temperature region, the flow direction of the solvent in the tubular reactor flows from the high-temperature region to the low-temperature region, and the material can be heated in a counter-current manner. On the other hand, the flow direction of the solvent in the tubular reactor ensures that the concentration gradient of the recovered organic matter contained in the solvent is increased from the high temperature region to the low temperature region.

The tubular reactor can be a continuous tubular reactor or a multi-section tubular reactor, and the state of each section of tubular reactor is controlled by a valve.

And step seven, separating the required organic matters from the liquid solvent containing the recoverable organic matters.

The separation of the desired organic material from the liquid solvent containing the recoverable organic material is carried out by distillation, evaporation, filtration and precipitation by a solvent-nonsolvent process.

The separated organic matter containing carbon atom number greater than 22 for further pyrolysis may be injected from the high temperature region of the tubular reactor for further pyrolysis.

And an eighth step of recovering the solvent discharged out of the tubular reactor together with the insoluble matter by means of a condenser and collecting the insoluble matter. The collected solvent may be condensed and heated again to be injected into the tubular reactor. Insoluble matter is often an inorganic substance contained in the solid to be recovered. Part of inorganic substances have high value and can be separated and collected for secondary utilization.

Drawings

FIG. 1 is a schematic flow diagram of the present invention.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to the following embodiments.

Example 1

The comminuted polystyrene plastic was mixed with toluene in a 101 stirred tank, in which the temperature was maintained at 60 ℃. The mixture was injected into a 105-tube reactor through a 102 high-pressure diaphragm pump 1 at a pressure of 12MPa. The material to be dissolved is fed 103 by a screw to the other end of the 105-tube reactor. The other end of the 105-tube reactor was heated with a 104-heating jacket to ensure a high temperature region of 375 deg.C, and was also charged with 375 deg.C toluene heated in a 110-solvent heating tank. The ball valve 1 was opened 108 and toluene containing dissolved organics was passed through a 106 tube filter and drained 107 to tank 1 for collection.

The ball valve 2 is opened 111 and the insolubles are discharged from the 105 tube reactor into the 112 surge tank 1. Ball valve 3 is opened 113 and the high temperature toluene is condensed by condenser 120 and flows into solvent collection tank 122. The non-condensable gasses may be collected or burned as fuel. The screw vacuum pump 119 was started, the ball valve 4 118 was opened, the star discharger 1 114 was opened, and insoluble matter was discharged into the buffer tank 2. Finally, the star discharger 2 was opened 116, and the insoluble matter was discharged into the insoluble matter collecting tank 117.

107 the solvent in reservoir 1 may be added with n-hexane to precipitate a portion of the polystyrene. The remaining solvent can be distilled to separate out components with boiling points above 410 ℃. Discharging the components with the boiling point of more than 410 ℃ into a 109 storage tank 2, and injecting the components into the 105 tubular reactor again through a 121 high-pressure diaphragm pump 2 for cracking.

Example 2

The crushed carbon fiber composite material and n-butanol are mixed in a 101 stirring tank, and the temperature in the stirring tank is kept at room temperature. The mixture was injected into a 105-tube reactor through a 102 high-pressure diaphragm pump 1 at a pressure of 7MPa. The material to be dissolved is fed 103 by a screw to the other end of the 105-tube reactor. The other end of the 105-tube reactor was heated with a 104-heating jacket to ensure a high temperature region temperature of 320 c, and further injected with 320 c n-butanol heated in a 110 solvent heating tank. The ball valve 1 is opened 108 and the n-butanol containing dissolved organics is passed through a 106 tube filter and discharged 107 to reservoir 1 for collection.

The ball valve 2 is opened 111 and the insolubles are discharged from the 105 tube reactor into the 112 surge tank 1. The ball valve 3 is opened 113 and the high temperature n-butanol is condensed by the condenser 120 and flows into the solvent collection tank 122. The non-condensable gasses may be collected or burned as fuel. The screw vacuum pump 119 was started, the ball valve 4 118 was opened, the star discharger 1 114 was opened, and insoluble matter was discharged into the buffer tank 2. Finally, the star discharger 2 was opened 116, and the insoluble matter was discharged into a 117 insoluble matter collecting tank.

Example 3

The crushed sludge was mixed with toluene in a 101 stirred tank where the temperature was maintained at 80 ℃. The mixture was injected into a 105-tube reactor through a 102 high-pressure diaphragm pump 1 at a pressure of 12MPa. The material to be dissolved is fed 103 by a screw to the other end of the 105-tube reactor. The other end of the 105-tube reactor was heated with a 104-heating jacket to ensure a high temperature region of 400 ℃ and was also charged with 400 ℃ toluene heated in a 110-solvent heating tank. Ball valve 1 is opened 108 and toluene containing dissolved organics is passed through a 106 tube filter and discharged 107 to tank 1 for collection.

The ball valve 2 is opened 111 and the insolubles are discharged from the 105 tube reactor into the 112 surge tank 1. Ball valve 3 is opened 113 and the high temperature toluene is condensed by condenser 120 and flows into solvent collection tank 122. The non-condensable gasses may be collected or combusted as fuel. The screw vacuum pump 119 was started, the ball valve 4 118 was opened, the star discharger 1 114 was opened, and insoluble matter was discharged into the buffer tank 2. Finally, the star discharger 2 was opened 116, and the insoluble matter was discharged into the insoluble matter collecting tank 117.

Example 4

The crushed tire particles were mixed with toluene in a 101 stirred tank, in which the temperature was maintained at 80 ℃. The mixture was injected into a 105-tube reactor through a 102 high-pressure diaphragm pump 1 at a pressure of 12MPa. The material to be dissolved is fed 103 by screws to the other end of the 105-tube reactor. The other end of the 105 tubular reactor was heated with a 104 heating mantle to ensure a high temperature zone of 360 ℃ and was also fed with 360 ℃ toluene heated in a 110 solvent heating tank. Ball valve 1 is opened 108 and toluene containing dissolved organics is passed through a 106 tube filter and discharged 107 to tank 1 for collection.

The ball valve 2 is opened 111 and the insolubles are discharged from the 105 tube reactor into the 112 surge tank 1. Ball valve 3 is opened 113 and the high temperature toluene is condensed by condenser 120 and flows into solvent collection tank 122. The non-condensable gasses may be collected or combusted as fuel. The screw vacuum pump 119 was started, the ball valve 4 118 was opened, the star discharger 1 114 was opened, and insoluble matter was discharged into the buffer tank 2. Finally, the star discharger 2 was opened 116, and the insoluble matter was discharged into a 117 insoluble matter collecting tank.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for recovering organic matters by supercritical fluid continuous extraction and pyrolysis comprises the following steps:

(1) Crushing solid substances to be recovered containing organic matters, then fully mixing with a solvent by stirring, and keeping a certain temperature.

(2) Continuously injecting the mixture uniformly stirred in the previous step into a tubular reactor with certain pressure by a high-pressure pump.

(3) One end of the tubular reactor for injecting the mixture is a low-temperature area, insoluble substances in the mixture are discharged from the other end of the tubular reactor, the insoluble substances discharge end is a high-temperature area, and a heating device and a high-temperature high-pressure solvent are injected.

(4) The spiral feeding device in the tubular reactor conveys the solid substances to be recovered from the low-temperature area at one end of the tubular reactor to the high-temperature area at the other end of the tubular reactor.

(5) During the process of conveying the solid to be recovered from the low-temperature area to the high-temperature area, organic matters contained in the solid are gradually dissolved or pyrolyzed by the solvent.

(6) The liquid solvent containing recoverable organic matters in the tubular reactor is discharged out of the tubular reactor from a liquid outlet of the low-temperature area of the tubular reactor, and insoluble matters are conveyed to the discharge outlet and discharged out of the tubular reactor.

(7) The desired organic material is separated from the liquid solvent containing the recoverable organic material and the organic material to be further cracked may be injected from the high temperature region of the tubular reactor.

(8) The solvent discharged out of the tubular reactor together with the insoluble matter was recovered by a condenser, and the insoluble matter was collected.

2. The method of claim 1, wherein the solid matter to be recovered containing organic matter comprises oil sands, oil shale, oil sludge; polyethylene plastics, polypropylene plastics, polyvinyl chloride plastics, polystyrene plastics, acrylonitrile-butadiene-styrene copolymer plastics, polymethacrylate plastics, ethylene-vinyl acetate copolymer plastics, polyethylene terephthalate plastics, polybutylene terephthalate plastics, polyamide plastics, polycarbonate plastics, polyformaldehyde plastics, polyphenyl ether plastics and polyurethane plastics; compounding epoxy resin and phenolic resin matrix with inorganic fiber material; tires, silicone rubber.

3. The process according to claim 1, wherein the solvent comprises one or more of methylene chloride, chloroform, tetrachloromethane, dioxane, aniline, dipropylamine, diisopropylamine, cyclohexanone, cyclohexane, benzene, benzaldehyde, toluene, xylene, n-hexane, n-pentane, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, n-propanol, isopropanol, n-butanol, acetonitrile, water, carbon dioxide, and combinations thereof.

4. The process of claim 1 wherein said agitation is maintained at a temperature between ambient temperature and the atmospheric boiling point of the solvent.

5. The process according to claim 1, wherein the pressure in the tubular reactor is higher than the critical pressure of the solvent, and the temperature of the high-temperature zone and the temperature of the injected solvent are higher than the critical temperature of the solvent.

6. The method according to claim 1, wherein the local region of the tubular reactor is at an angle of more than 15 degrees with respect to the horizontal plane, so that a liquid seal is formed between the liquid phase and the supercritical phase interface of the solvent in the tubular reactor, and the liquid seal interface ensures that the supercritical fluid is not discharged from the low-temperature region liquid outlet.

7. The process of claim 1, wherein the tubular reactor is a continuous tubular reactor or a multi-stage tubular reactor, and the state of each tubular reactor is controlled by a valve.

8. The method of claim 1, wherein the desired organic compound is separated from the liquid solvent containing the recoverable organic compound by distillation, evaporation, filtration, or precipitation from a solvent-nonsolvent.

9. The process of claim 1, wherein the organic material to be further cracked is the separated organic material containing more than 22 carbon atoms as defined in claim 8.

10. The process of claim 3 wherein the solvent contains a catalyst selected from the group consisting of alumina, molecular sieves, ammonium fluoride, tetrabutylammonium fluoride.