CN116064069A

CN116064069A - System and method for preparing fuel oil from waste plastics

Info

Publication number: CN116064069A
Application number: CN202310256278.4A
Authority: CN
Inventors: 辛本恩; 叶宗君; 李金城
Original assignee: Zhejiang Kemao Environmental Technology Co ltd
Current assignee: Zhejiang Kemao Environmental Technology Co ltd
Priority date: 2023-03-16
Filing date: 2023-03-16
Publication date: 2023-05-05

Abstract

The present application relates to a method for preparing fuel oil from waste plastics, comprising S1: in the presence of a catalyst and a first heating medium, waste plastics are subjected to cracking reaction in a first reactor to obtain oil gas components and residues; s2: separating the oil-gas component to obtain a heavy oil component and a non-heavy oil-gas component; s3: carrying out catalytic recombination on the non-heavy oil gas component to obtain a refined oil gas component; s4: heat exchange is carried out on the refined oil gas component and the low-temperature heating medium, so as to obtain a high-temperature heating medium and a refined oil gas component after cooling; s5: condensing the refined oil gas component after cooling to obtain the fuel oil. The present application also relates to a system for preparing fuel oil from waste plastics. The method can directly convert the waste plastic into the fuel oil, has high recovery rate of the waste plastic and energy conservation, solves the problem of high energy consumption in the deep processing process of the waste plastic oil, improves the quality of the plastic oil, and ensures that the catalytic conversion reaction of the plastic oil generates more low-carbon olefins.

Description

System and method for preparing fuel oil from waste plastics

Technical Field

The application relates to the technical field of garbage disposal and chemical recovery of waste plastics, in particular to a system and a method for preparing fuel oil from waste plastics.

Background

The plastic market demand of China is increased year by year, about 4000 ten thousand tons of waste plastic are produced annually, and the recycling rate is low. At present, waste plastic treatment means are gradually changed from landfill and incineration to recycling mainly including physical recycling, chemical recycling and the like.

The preparation of waste plastics into fuel oil can realize the recycling of waste plastics, and therefore, the waste plastics are attracting attention. For example, chinese patent application publication No. CN104611030a discloses a coking method for producing fuel oil from waste plastics, comprising (1) preheating high aromatic components and waste plastics or plastic oil by a raw material buffer tank, controlling heating rates of different temperature sections, heating the preheated raw material in a tubular heating furnace, and spraying into a delayed coking tower for coking reaction to obtain high-temperature oil gas and coke; (2) And (3) feeding the high-temperature oil gas obtained in the step (1) into a coking fractionating tower, and fractionating to obtain coking dry gas and at least one coking distillate. In this prior art document, the coker distillate is a coker whole distillate, or comprises both coker naphtha and coker diesel. The high aromatic component comprises one or more of ethylene tar, ethylene C9 component, catalytic pyrolysis external oil slinger, MIP diesel, high temperature coal tar heavy benzene, naphthalene oil, wash oil and anthracene oil, shale oil and oil sand asphalt at 150-600 ℃; the waste plastic is one or more of polyethylene, polypropylene and polystyrene.

Chinese patent application publication No. CN103980938A discloses a method for producing clean fuel from chlorine-containing plastic oil, comprising injecting chlorine-containing plastic oil into a catalytic distillation column containing molecular sieve/alumina catalyst for reaction and rectification; after catalytic cracking, chlorine-containing plastic oil enters a low-pressure liquid-phase hydrogenation tower through heat exchange to carry out hydrodechlorination, and the catalyst is a supported metal catalyst; the distillate oil after liquid phase hydrogenation enters a water washing tower, a lower water phase at the bottom of the tower is circulated, an upper distillate oil phase after water washing enters a hydrogenation refining tower through pressurization, hydrogenation quality improvement is carried out, a catalyst used for hydrogenation refining is a sulfide catalyst, mono-olefin hydrogenation saturation reaction is carried out to remove mono-olefin compounds, no peculiar smell and high-quality gasoline and diesel oil mixed oil is produced through desulfurization, nitrogen removal and colloid removal, gasoline and diesel oil distillate oil is obtained through distillation, and heavy oil at the bottom of the tower and raw material chlorine-containing plastic oil are mixed and re-reacted.

It is known from the above prior art documents that in order to convert waste plastics into usable fuel oil, either an additional high aromatic component is added or the waste plastics are converted into plastic oil first, and then the plastic oil is hydrogenated and decontaminated through a complicated process to obtain the fuel oil.

For this reason, there is a need in the art to develop a system and method for preparing fuel oil from waste plastics with high recovery and energy saving.

Disclosure of Invention

The present application aims to provide a method for preparing fuel oil from waste plastics with high recovery rate and energy saving, thereby solving the technical problems in the prior art. Specifically, the method comprises the steps of carrying out catalytic recombination on non-heavy oil gas components obtained by cracking waste plastics to obtain refined oil gas components, and condensing the refined oil gas components after heat exchange with a heating medium to recover heat to obtain fuel oil. Preferably, the methods described herein further comprise returning the heavy oil component obtained by pyrolysis of the waste plastic to the first reactor where the plastic pyrolysis is performed for recycling, reducing carbon and hydrogen losses in the waste plastic, and increasing the overall yield of waste plastic recovery.

It is also an object of the present application to provide a system for preparing fuel oil from waste plastics.

In order to solve the technical problems, the application provides the following technical scheme.

In a first aspect, the present application provides a method of preparing fuel oil from waste plastics, the method comprising the steps of:

s1: in the presence of a catalyst and a first heating medium, waste plastics are subjected to cracking reaction in a first reactor to obtain oil gas components and residues;

s2: separating the oil and gas components to obtain a heavy oil component and a non-heavy oil and gas component;

s3: carrying out catalytic recombination on the non-heavy oil gas component to obtain a refined oil gas component;

s4: performing heat exchange between the refined oil gas component and a low-temperature heating medium to obtain a high-temperature heating medium and a refined oil gas component after cooling;

s5: condensing the refined oil gas component after cooling to obtain the fuel oil.

In a second aspect, the present application provides a system for preparing fuel oil from waste plastics, the system comprising:

the first reactor is used for carrying out cracking reaction on the waste plastics to obtain oil gas components and residues;

a separation device for separating the oil and gas components into a heavy oil component and a non-heavy oil and gas component;

the second reactor is used for carrying out catalytic recombination on the non-heavy oil gas component to obtain a refined oil gas component;

the heat exchange device is used for carrying out heat exchange on the refined oil gas component and the low-temperature heating medium to obtain a high-temperature heating medium and a refined oil gas component after cooling;

and the condensing device is used for condensing the refined oil gas component after cooling to obtain fuel oil.

Compared with the prior art, the invention has the beneficial effects that the invention can directly convert waste plastic into fuel oil, has high recovery rate of waste plastic and saves energy, solves the problem of high energy consumption in the deep processing process of waste plastic oil, improves the quality of the plastic oil, ensures that the catalytic conversion reaction of the plastic oil generates more low-carbon olefin, meets the market demand for low-carbon olefin, improves the utilization value of the waste catalytic cracking catalyst, and brings great economic and social benefits for petrochemical industry

Drawings

Fig. 1 shows a system for producing light low olefin plastic pyrolysis oil from waste plastic according to one embodiment.

In the drawings, the reference numerals have the following meanings:

1. a feeding device; 2. a first reactor 3, a separation device; 4. a second reactor; 5. a heat exchange device; 6. a condensing device; 61. a first stage condenser; 62. a second stage condenser; 63. and a third stage condenser.

Detailed Description

Where applicable, the disclosure of any patent, patent application, or publication referred to in this application is incorporated by reference in its entirety, and the equivalent of such patent is incorporated by reference, particularly as they disclose definitions of catalysts, waste plastics, cracking, and the like in the art. If the definition of a particular term disclosed in the prior art does not conform to any definition provided in this application, the definition of that term provided in this application controls.

The terms "comprises," "comprising," "including," and their derivatives do not exclude the presence of any other component, step or procedure, and are not related to whether or not such other component, step or procedure is disclosed in the present application. For the avoidance of any doubt, all use of the terms "comprising," "including," or "having" herein, unless expressly stated otherwise, may include any additional additive, adjuvant, or compound. Rather, the term "consisting essentially of … …" excludes any other component, step or process from the scope of any of the terms recited below, except as necessary for operability. The term "consisting of … …" does not include any components, steps or processes not specifically described or listed. The term "or" refers to the listed individual members or any combination thereof unless explicitly stated otherwise.

Definition of terms

As used herein, the term "plastic oil" refers to the liquid phase product (at normal temperature and pressure) produced by thermal or catalytic cracking of waste plastics.

As used herein, the term "heavy oil component" refers to hydrocarbon compounds having a boiling point greater than 380 ℃ and a carbon chain comprising greater than or equal to 20 carbon atoms.

As used herein, the term "non-heavy oil component hydrocarbon component" refers to the material remaining after separation of the condensed liquid heavy oil component from the hydrocarbon component at a temperature below the boiling point of the heavy oil component.

The system and method for preparing fuel oil from waste plastics described herein will be described in detail with reference to fig. 1.

In a first aspect, the present application relates to a method for preparing fuel oil from waste plastics, the method comprising the steps of: s1: in the presence of a catalyst and a first heating medium, waste plastics are subjected to cracking reaction in a first reactor to obtain oil gas components and residues; s2: separating the oil and gas components to obtain a heavy oil component and a non-heavy oil and gas component; s3: carrying out catalytic recombination on the non-heavy oil gas component to obtain a refined oil gas component; s4: performing heat exchange between the refined oil gas component and a low-temperature heating medium to obtain a high-temperature heating medium and a refined oil gas component after cooling; s5: condensing the refined oil gas component after cooling to obtain the fuel oil.

In one embodiment, step S1 may be performed in a first reactor. The purpose of step S1 is to make the waste plastics undergo the pyrolysis reaction under the catalysis of pyrolysis catalyst, so as to obtain oil gas component and residue. In step S1, the reaction temperature may be 300-600 ℃. This can be achieved by feeding a first heating medium into the first reactor. The first heating medium may be a superheated gas, a heat transfer oil, or a mineral oil, for example, superheated steam at 550 to 650 ℃ or a high-temperature inert gas, or the like. In one embodiment, the catalyst and waste plastics may be stirred to mix homogeneously for cracking reaction, the oil and gas components and residues are collected and produced, the oil and gas components enter the separation device through the top of the first reactor, and the residues may be discharged from the system through the bottom of the first reactor. In one embodiment, the residue from the evacuation system may be sent to a downstream processing device for further processing or to a downstream collection device for collection.

In a preferred embodiment, the method further comprises the steps of: s6: the waste plastics are added by a feeding device to the first reactor where step S1 is carried out. During the process of adding the waste plastics to the first reactor, a second heating medium is continuously added to the feeding device. Preferably, the waste plastic can be pretreated, the size range of the pretreated waste plastic is about 5mm, and the components of the waste plastic comprise PVC, PP, PE, PS and other components. The second heating medium is continuously added into the feeding device, so that materials can be effectively mixed, and waste plastics are uniformly dispersed into the first reactor containing the catalyst. In this case, the temperature of the second heating medium may be 100-300 deg.c, which is lower than the temperature at which the waste plastics in the first reactor undergo the pyrolysis reaction. Because the second heating medium is used to preheat the waste plastic rather than to crack it.

In one embodiment, step S2 may be implemented in a separation device. In one embodiment, the hydrocarbon component obtained in step S1 may be sent to a separation device, and step S2 includes condensing the hydrocarbon component to a temperature greater than the boiling point of the non-heavy oil hydrocarbon component but less than or equal to the boiling point of the heavy oil component. In this case, the heavy oil component condenses into a liquid, which can be discharged from the bottom of the separation device out of the system. Alternatively, step S8 may be performed, namely, recycling the heavy oil component to the first reactor for reprocessing. While the non-heavy oil hydrocarbon component remains in the gaseous state and can be transported from the top of the separation device to the second reactor.

In one embodiment, step S3 may be performed in a second reactor. In other words, the non-heavy oil gas component fed to the second reactor may undergo catalytic recombination reaction in the second reactor to obtain a refined oil gas component. In one embodiment, catalytic recombination comprises: (1) a reaction between olefins to form alkanes and aromatics; and/or, (2) the C3-C4 components are superimposed to form a long chain olefin. In a preferred embodiment, the non-heavy oil hydrocarbon component may also be decontaminated prior to its recombination. In the step S3, the reaction temperature for carrying out catalytic recombination on the non-heavy oil gas component is 50-550 ℃, and the reaction pressure is 0.1-10.0MPa.

In one embodiment, step S4 may be performed by a heat exchange device. Specifically, step S4 may include passing the refined oil gas component and the low temperature heating medium through different flow passages of the heat exchange device, respectively, so that the refined oil gas component and the low temperature heating medium exchange heat, thereby obtaining the refined oil gas component after the high temperature heating medium and the temperature reduction. In other words, the refined oil gas component may be used to heat the low temperature heating medium to a desired temperature. In this case, step S7 may also be implemented. That is, the high-temperature heating medium obtained in step S4 is used as at least one of the first heating medium and the second heating medium. Specifically, the high temperature heating medium obtained after heating the refined oil gas component may be recycled to the first reactor to be used as the first heating medium, or recycled to the feeding device to be used as the second heating medium.

In one embodiment, step S5 may be implemented in a condensing unit. In a preferred embodiment, step S5 comprises fractional condensation of the refined oil gas component after cooling to yield C1-C4 component, C5-C10 component plastic oil and C10-C22 plastic oil, respectively. In one embodiment, the refined oil and gas component may be subjected to a three stage condensation, the first stage condensation temperature being 80-120 ℃, the second stage condensation temperature being 50-80, and the third stage condensation temperature being 30-50 ℃.

In a second aspect, the present application provides a system for preparing fuel oil from waste plastic. Referring to fig. 1, the system may include a first reactor, a separation device, a second reactor, a heat exchange device, a condensing device, and optionally a feed device in sequential communication. In this embodiment, the first reactor is used to subject waste plastics to a cracking reaction to yield oil and gas components and residues. The separation device is used for separating the oil-gas component into a heavy oil component and a non-heavy oil-gas component. And the second reactor is used for carrying out catalytic recombination on the non-heavy oil gas component to obtain a refined oil gas component. The heat exchange device is used for carrying out heat exchange on the refined oil gas component and the low-temperature heating medium to obtain the high-temperature heating medium and the refined oil gas component after cooling. The condensing device is used for condensing the refined oil gas component after cooling to obtain fuel oil. A feeding device is used for adding the waste plastics to the first reactor. In a preferred embodiment, the feeding means may be an extrusion apparatus comprising a feeding bin and an extrusion pipe, and, at the time of feeding, the pretreated waste plastics are first fed to the feeding bin, and then the waste plastics in the feeding bin are extruded from the extrusion pipe by an extruder while a fluid medium (high temperature gas, water, air, heat transfer oil, mineral oil, etc.) of 100-300 ℃ is blown at the extrusion pipe, and the waste plastics are fed to the first reactor containing the catalyst.

In a preferred embodiment, heat exchange means is in communication with at least one of the feed means and the first reactor for delivering a high temperature heating medium to at least one of the feed means and the first reactor.

In a preferred embodiment, the separation device is in communication with the first reactor for delivering the heavy oil component to the first reactor.

The operation of the system for preparing fuel oil from waste plastics described herein will be described with reference to fig. 1.

First, waste plastic may be added to the feeding device 1 through the waste plastic input pipe 101, and a second heating medium may be input into the feeding device 1 through the second heating medium input pipe 102. The second heating medium may be used to mix the waste plastics, prevent clogging, and uniformly disperse the waste plastics to the first reactor 2. The feeding device 1 may be in direct contact with the second reactor 2 or may be in communication via an extrusion line 103, the feeding device 1 delivering waste plastics to the first reactor 2. The first heating medium is input into the first reactor 2 through the first heating medium input pipe 203, and the first reactor 2 may be previously provided with a catalyst. The waste plastics undergo catalytic cracking reaction in the first reactor 2 to obtain an oil-gas component and residues, the oil-gas component can be conveyed to the separation device 3 through an oil-gas component output pipeline 201, and the residues can be discharged out of the first reactor through a residue output pipeline 202. The oil-gas component is condensed and separated in the separating device 3 to obtain a heavy oil component and a non-heavy oil-gas component. The non-heavy oil components may be transferred from the separation device 3 to the second reactor 4 through the separation device output conduit 301. At the same time, heavy oil components may be recycled from separation device 3 to the first reactor via first recycle line 302. The non-heavy oil gas component is catalyzed and recombined in the second reactor 4 to obtain refined oil gas component, the refined oil gas component is conveyed to the heat exchange device 5 through the output pipeline 401 of the second reactor, and the refined oil gas component after cooling is conveyed to the first-stage condenser 61 through the output pipeline 502 of the heat exchange device. At the same time, a low-temperature heating medium (for example, a heating medium at normal temperature or room temperature) may be input into the other flow passage of the heat exchange device through the low-temperature heating medium input pipe 502, and a high-temperature heating medium obtained after the temperature is raised may be transferred from the heat exchange device 5 to the feeding device 1 or the first reactor 2 through the second circulation pipe 502.

The oil gas component after cooling down can be subjected to stage condensation in the first stage condenser 61, the second stage condenser 62 and the third stage condenser 63 connected in series, wherein the condensation temperatures of the first stage condenser 61, the second stage condenser 62 and the third stage condenser 63 are sequentially reduced. The cooled oil and gas components are first condensed in a first stage condenser 61, and the resulting C13-C22 plastic oil is discharged from the first output pipe 601 to a downstream processing or collection device. The remainder of the material is conveyed to the second stage condenser 62 through the second output pipe 602 for continuous condensation, and the condensed C5-C12 component plastic oil is discharged from the system through the third output pipe 603 and conveyed to a downstream processing device or collection device. The remainder of the material is fed via a fourth output line 604 to a third stage condenser 63 for continued condensation, and the condensed C1-C4 components are discharged from the fifth output line 605 to a downstream processing or collection unit. The remaining portion of the residue or material may then exit the system through a sixth output conduit 606.

Examples

The technical solutions of the present application will be clearly and completely described below in connection with the embodiments of the present application. The reagents and starting materials used were purchased commercially, unless otherwise indicated. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.

Examples 1 to 5

Examples 1-5 relate to the use of waste plastics for the preparation of fuel oils.

The specific procedures of examples 1-5 are as follows.

Waste plastics are added into a first reactor 2 containing a catalyst through a feeding device 1, and the waste plastics undergo catalytic cracking reaction in the first reactor 2 to obtain oil gas components and residues. The oil and gas components are fed to the separation device 3, the temperature of the separation device is raised to a predetermined temperature, the heavy oil components are condensed into liquid, and the oil and gas components are separated into heavy oil components and non-heavy oil and gas components. The heavy oil component is pumped into the first reactor by a pump for reprocessing. And conveying the non-heavy oil gas component to a second reactor 4 for catalytic recombination reaction to obtain the refined oil gas component. The refined oil gas component is conveyed to a heat exchange device 5, cooled and then conveyed to a first-stage condenser 61, a second-stage condenser 62 and a third-stage condenser 63 which are connected in series for fractional condensation to obtain C13-C22 plastic oil, C5-C12 component plastic oil and C1-C4 component respectively. At the same time, low-temperature steam is fed to the heat exchanger 5, and is circulated to the feeder 1 after the temperature is raised.

Examples 1-5 the raw material components of the added waste plastics are shown in Table 1.

TABLE 1 waste Plastic Components and contents added in examples 1 to 5

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The types of products, yields and waste plastic recovery rates of this example are shown in Table 2.

TABLE 2 types of products, yields and recovery of waste plastics

In table 2, the plastic recovery rate refers to the ratio (mass fraction) of the product to the waste plastic, excluding the moisture content in the original waste plastic. As can be seen from table 2, in the mixture of waste plastics, as the PS and PV ratios increase, the recovery rate of waste plastics increases correspondingly, the liquefied gas content in the product decreases, and the aromatic hydrocarbon content increases; when only the PP component is in the waste plastic components, the recovery rate of the waste plastic is the lowest, most of the waste plastic is liquefied gas, and a small amount of the waste plastic is aromatic hydrocarbon.

The catalysts and reaction conditions used in the reactors of examples 1-5 are shown in Table 3.

TABLE 3 reaction conditions for different reactors

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The embodiments are described above in order to facilitate the understanding and application of the present application by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be made to these embodiments and that the general principles described herein may be applied to other embodiments without the use of inventive faculty. Accordingly, the present application is not limited to the embodiments herein, and those skilled in the art, based on the present disclosure, may make improvements and modifications without departing from the scope and spirit of the present application.

Claims

1. A method for preparing fuel oil from waste plastics, the method comprising the steps of:

2. The method of claim 1, further comprising the step of:

s6: adding the waste plastic to a first reactor performing step S1 by a feeding device;

wherein a second heating medium is continuously added to the feeding means during the process of adding the waste plastics to the first reactor.

3. The method of claim 2, further comprising the step of:

s7: the high-temperature heating medium obtained in step S4 is used as at least one of the first heating medium and the second heating medium.

4. The method of claim 1, further comprising the step of:

s8: and recycling the heavy oil component obtained in the step S2 to the first reactor for recycling.

5. The process according to any one of claims 1 to 4, wherein in step S1 the reaction temperature is 300 to 600 ℃.

6. The method of any of claims 1-4, wherein step S2 comprises condensing the hydrocarbon component to a temperature greater than the boiling point of the non-heavy oil hydrocarbon component but less than or equal to the boiling point of the heavy oil component.

7. The method of any one of claims 1-4, wherein in step S3, the catalytic reforming of the non-heavy oil and gas component is performed at a reaction temperature of 50-550 ℃ and a reaction pressure of 0.1-10.0MPa.

8. The method of any one of claims 1-4, wherein step S5 comprises fractional condensation of the refined oil gas component after cooling to yield a small amount of C1-C4 component, C5-C10 component plastic oil, and a major portion of C10-C22 fuel oil, respectively.

9. A system for producing fuel oil from waste plastic, the system comprising:

10. The system of claim 9, wherein the system further comprises:

and a feeding device for adding the waste plastics to the first reactor.

11. The system of claim 10, wherein the heat exchange device is in communication with at least one of the feed device and the first reactor for delivering a high temperature heating medium to the at least one of the feed device and the first reactor.

12. The system of any one of claims 9-11, wherein the separation device is in communication with the first reactor for delivering the heavy oil component to the first reactor.