CN112251251A - Industrial continuous classified cracking system and process for mixed waste plastics - Google Patents

Industrial continuous classified cracking system and process for mixed waste plastics Download PDF

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Publication number
CN112251251A
CN112251251A CN202011052638.1A CN202011052638A CN112251251A CN 112251251 A CN112251251 A CN 112251251A CN 202011052638 A CN202011052638 A CN 202011052638A CN 112251251 A CN112251251 A CN 112251251A
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China
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stage
oil
gas
reaction furnace
outlet
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Inventor
汪传生
田晓龙
卫健
汪国春
平伟
李文昱
李绍明
张德伟
边慧光
郝国强
李利
郭磊
尹凤福
陈宏波
韩雯雯
刘海超
梁辉
曹梦龙
徐东彦
毕海胜
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Wuxi Jinqiu Machinery Co Ltd
Qingdao University of Science and Technology
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Wuxi Jinqiu Machinery Co Ltd
Qingdao University of Science and Technology
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Priority to CN202011052638.1A priority Critical patent/CN112251251A/en
Priority to PCT/CN2020/120684 priority patent/WO2022067882A1/en
Publication of CN112251251A publication Critical patent/CN112251251A/en
Pending legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
    • C10B53/07—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form of solid raw materials consisting of synthetic polymeric materials, e.g. tyres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/02—Particle separators, e.g. dust precipitators, having hollow filters made of flexible material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/007—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by irradiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B33/00—Discharging devices; Coke guides
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B43/00—Preventing or removing incrustations
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B49/00—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated
    • C10B49/02—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated with hot gases or vapours, e.g. hot gases obtained by partial combustion of the charge
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
    • C10B57/08—Non-mechanical pretreatment of the charge, e.g. desulfurization
    • C10B57/10—Drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/804—UV light
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock
    • Y02P20/143—Feedstock the feedstock being recycled material, e.g. plastics

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Biomedical Technology (AREA)
  • Toxicology (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)

Abstract

The invention relates to a mixed waste plastic industrial continuous classified cracking system and process, which comprises an extrusion dryer, a first-stage lifting screw conveyor, a second-stage lifting screw conveyor, a catalytic mixing material cylinder, a semi-plasticizing feeder, a first-stage cracking reaction furnace, a second-stage cracking reaction furnace, a first-stage deslagging screw, a second-stage cracking reaction furnace, a third-stage deslagging screw, a separator, a slag storage tank, a first-stage filter, a second-stage filter, a third-stage filter, a first-stage settling tower, a second-stage settling tower, a first-stage air-cooling heat exchanger, a second-stage air-cooling heat exchanger, a third-stage water-cooling heat exchanger, a first-stage gas-liquid separation tank, a second-stage oil tank, a third-stage. The invention provides a mixed plastic similar cracking method according to the characteristics of different types of plastics and different cracking temperatures, and the economic added value of a cracking product is improved by separately recovering a cracking oil product; the energy consumption in the cracking process is reduced by recycling and burning the non-condensable combustible gas and recycling high-temperature waste heat, and the environmental pollution is avoided by carrying out a plurality of purification steps on the waste gas.

Description

Industrial continuous classified cracking system and process for mixed waste plastics
Technical Field
The invention belongs to the technical field of solid waste resource utilization, and particularly relates to an industrial continuous classified cracking system and process for mixed waste plastics.
Background
At present, several existing methods for treating waste plastics in China mainly comprise the following steps: the first is recycled plastics made into plastic granules, which require higher quality plastics such as beverage bottles; secondly, the waste water is directly incinerated or buried, and the treatment mode is simple but causes serious pollution to the environment; and thirdly, the fuel oil is generated by recycling, which has low requirements on the quality of the plastic and can create better social benefit and economic benefit. Especially, the waste plastics in the domestic garbage and the stale garbage can not be sorted for reuse, and can only be finally treated by cracking, burning and the like.
The cracking can convert the waste plastics into oil rich in aromatic hydrocarbon, gas with high fuel value and recyclable carbon rods, and becomes the most effective way for recycling the waste plastics in household garbage and stale garbage. But the waste plastics in the domestic garbage and the stale garbage have complex components and contain a large amount of components such as percolate, mud, bricks and the like, so that the difficulty of continuous cracking is increased; meanwhile, in the cracking process, the cracking temperature is high, flammable and explosive gas is generated by cracking, the safety of the cracking process is difficult to guarantee, and the cracking industrial application is difficult, and in addition, the cracking technology does not distinguish the types of raw materials at present, the cracking is carried out by adopting a single cracking temperature mode, so that the components of a cracking product are complex, valuable key materials cannot be extracted from the cracking product, the value of a cracked oil product is low, so that cracking manufacturers have no economic benefit, and the continuous classified cracking of mixed plastics such as household garbage, aged garbage and the like in the current plastic industry cannot be realized.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide the industrial continuous classified cracking system and the process for the mixed waste plastics, which can improve the economic added value of the recycled oil bottles, reduce the energy consumption and avoid environmental pollution.
According to the technical scheme provided by the invention, the industrial continuous classified cracking system for mixed waste plastics comprises an extrusion dryer, a primary lifting screw conveyor, a catalytic mixing cylinder, a secondary lifting screw conveyor, a semi-plasticizing feeder, a primary cracking reaction furnace, a secondary cracking reaction furnace, a tertiary cracking reaction furnace, a slag discharge primary screw, a slag discharge secondary screw, a slag discharge tertiary screw, a slag storage tank, a separator, a first basket filter, a second basket filter, a third basket filter, a primary settling tower, an air-cooled primary heat exchanger, a water-cooled primary heat exchanger, a primary gas-liquid separation tank, a secondary settling tower, an air-cooled secondary heat exchanger, a water-cooled secondary heat exchanger, a secondary gas-liquid separation tank, a tertiary settling tower, an air-cooled tertiary heat exchanger, a water-cooled tertiary heat exchanger, a tertiary gas-liquid separation tank, a first oil tank, a second oil tank, a third oil tank, The device comprises a noncondensable fuel gas purifier, a tail gas treatment module, a combustion chamber and a combustor;
the plastic outlet of the extrusion dryer is connected with the plastic inlet of the first-level lifting screw conveyor, the plastic outlet of the first-level lifting screw conveyor is connected with the plastic inlet of the catalytic mixing cylinder, the plastic outlet of the catalytic mixing cylinder is connected with the plastic inlet of the second-level lifting screw conveyor, the plastic outlet of the second-level lifting screw conveyor is connected with the plastic inlet of the semi-plasticizing feeder, the plastic outlet of the semi-plasticizing feeder is connected with the plastic inlet of the first-level cracking reaction furnace, the plastic outlet of the first-level cracking reaction furnace is connected with the plastic inlet of the second-level cracking reaction furnace, the plastic outlet of the second-level cracking reaction furnace is connected with the plastic inlet of the third-level cracking reaction furnace, the slag outlet of the third-level cracking reaction furnace is connected with the slag inlet of the separator, the anti-coking ball outlet of the separator is connected with the anti-coking ball inlet of the first-level cracking reaction furnace, and the slag outlet of the slag discharge, the slag outlet of the slag discharging primary screw is connected with the slag inlet of the slag discharging secondary screw, the slag outlet of the slag discharging secondary screw is connected with the slag inlet of the slag discharging tertiary screw, and the slag outlet of the slag discharging tertiary screw is connected with the slag inlet of the slag storage tank;
the waste gas outlet of the first-stage cracking reaction furnace, the waste gas outlet of the second-stage cracking reaction furnace, the waste gas outlet of the third-stage cracking reaction furnace and the waste gas outlet of the extrusion dryer are all connected with the waste gas inlet of a tail gas treatment module, and the tail gas treatment module comprises a filter bag dust collector, a surface cooler, a UV (ultraviolet) photo-catalytic furnace and an activated carbon box;
an oil gas outlet of the first-stage cracking reaction furnace is connected with an oil gas inlet of a third basket filter, an oil gas outlet of the third basket filter is connected with an oil gas inlet of a third-stage settling tower, an oil liquid outlet of the third-stage settling tower is connected with an oil liquid inlet of a third oil tank, an oil gas outlet of the third-stage settling tower is connected with an oil gas inlet of an air-cooled third-stage heat exchanger, an oil gas outlet of the air-cooled third-stage heat exchanger is connected with an oil gas inlet of a water-cooled third-stage heat exchanger, an oil gas outlet of the water-cooled third-stage heat exchanger is connected with an oil gas inlet of a third-stage gas-liquid separation;
an oil gas outlet of the second-stage cracking reaction furnace is connected with an oil gas inlet of a first basket filter, an oil gas outlet of the first basket filter is connected with an oil gas inlet of a first-stage settling tower, an oil liquid outlet of the first-stage settling tower is connected with an oil liquid inlet of the oil tank, an oil gas outlet of the first-stage settling tower is connected with an oil gas inlet of an air-cooled first-stage heat exchanger, an oil gas outlet of the air-cooled first-stage heat exchanger is connected with an oil gas inlet of a water-cooled first-stage heat exchanger, an oil gas outlet of the water-cooled first-stage heat exchanger is connected with an oil gas inlet of a first-stage gas-liquid;
an oil gas outlet of the third-stage cracking reaction furnace is connected with an oil gas inlet of a second basket filter, an oil gas outlet of the second basket filter is connected with an oil gas inlet of a second-stage settling tower, an oil liquid outlet of the second-stage settling tower is connected with an oil liquid inlet of the oil tank, an oil gas outlet of the second-stage settling tower is connected with an oil gas inlet of an air-cooling second-stage heat exchanger, an oil gas outlet of the air-cooling second-stage heat exchanger is connected with an oil gas inlet of a water-cooling second-stage heat exchanger, an oil gas outlet of the water-cooling second-stage heat exchanger is connected with an oil gas inlet of a second-stage gas-liquid;
the high-temperature flue gas outlet of the combustion chamber is connected with the high-temperature flue gas inlet of the first-stage cracking reaction furnace, the high-temperature flue gas inlet of the second-stage cracking reaction furnace and the high-temperature flue gas inlet of the third-stage cracking reaction furnace.
Preferably, the furnace bodies of the first-stage cracking reaction furnace, the second-stage cracking reaction furnace and the third-stage cracking reaction furnace are surrounded by refractory bricks and covered with heat-insulating materials for heat preservation.
Preferably, the outer jackets of the deslagging primary screw are provided with circulating water cooling structures.
Preferably, a jacket heat preservation structure is arranged on a pipeline between a non-condensable combustible gas outlet of the non-condensable combustible gas purifier and a non-condensable combustible gas inlet of the burner.
Preferably, a pipeline between an oil gas outlet of the first-stage cracking reaction furnace and an oil gas inlet of the third basket filter, a pipeline between an oil gas outlet of the second-stage cracking reaction furnace and an oil gas inlet of the first basket filter, and a pipeline between an oil gas outlet of the third-stage cracking reaction furnace and an oil gas inlet of the second basket filter are all made of 316L stainless steel.
An industrial continuous classified cracking process for mixed waste plastics comprises the following steps:
dehydrating and preplasticizing: dehydrating and preplasticizing: the extrusion dryer, the primary lifting screw conveyor, the catalytic mixing material cylinder, the secondary lifting screw conveyor and the semi-plasticizing feeder are heated to 100-150 ℃ by infrared heating, mixed waste plastics firstly enter the extrusion dryer, the waste plastics are dehydrated under the extrusion action of a dehydration screw in the extrusion dryer, the dehydrated waste plastics are conveyed into the catalytic mixing material cylinder by the primary lifting screw conveyor, and the extruded waste plastics enter the catalytic mixing material cylinder and are instantaneously opened and fluffy, so that the water which is not removed in the extrusion process is released; simultaneously, the catalyst is added into the catalytic mixing cylinder, the mixed waste plastic and the catalyst are uniformly mixed under the action of the conical screw of the catalytic mixing cylinder, then the mixed waste plastic and the catalyst enter a semi-plasticizing feeder through a secondary lifting screw conveyor, the waste plastic is converted into a semi-plasticizing state through temperature rise and enters a primary cracking reaction furnace together with an anti-coking ball;
(II) pyrolysis according to the types: in the earlier stage of the cracking reaction, supplying heat for a first-stage cracking reaction furnace, a second-stage cracking reaction furnace and a third-stage cracking reaction furnace by using outsourced natural gas and generating high-temperature flue gas at 1000-1200 ℃ after combustion by a burner; wherein the cracking temperature of the primary cracking reaction furnace is controlled to be 300-350 ℃ through the fan amount, so that the cracking of PVC plastics in the mixed waste plastics is realized; controlling the cracking temperature of the secondary cracking reaction furnace to be 400-450 ℃ through the fan amount, and cracking PP and PE plastics in the mixed waste plastics; controlling the cracking temperature of the three-stage cracking reaction furnace to be 500-550 ℃ by using the fan to realize the cracking of the ABS plastics in the mixed waste plastics;
(III) deslagging: deslagging: carbon black and anti-coking balls generated by pyrolysis of the third-stage pyrolysis furnace firstly enter a separator, the anti-coking balls separated by the separator return to the first-stage pyrolysis reaction furnace, the carbon black separated by the separator enters a deslagging first-stage screw, enters a deslagging second-stage screw under the lifting of the deslagging first-stage screw, continues to lift to a deslagging third-stage screw, and is sent to a slag storage tank for storage after being cooled;
(IV) oil gas recovery: oil gas generated by the first-stage cracking reaction furnace firstly passes through a third basket filter to remove solid ash in the oil gas, then enters a third-stage settling tower to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the third-stage settling tower, the uncondensed oil gas enters an air-cooled third-stage heat exchanger and then enters a water-cooled third-stage heat exchanger, most of oil in the oil gas is condensed out in the air-cooled third-stage heat exchanger and the water-cooled third-stage heat exchanger, the condensed oil and uncondensed combustible gas enter a third-stage gas-liquid separation tank to realize oil-gas separation, and pyrolysis oil is collected and stored in a third oil tank;
oil gas generated by the secondary cracking reaction furnace firstly passes through a first basket filter to remove solid ash in the oil gas, then enters a primary settling tower to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the primary settling tower, the oil gas which is not condensed enters an air-cooled primary heat exchanger and then enters a water-cooled primary heat exchanger, most of oil in the oil gas is condensed out in the air-cooled primary heat exchanger and the water-cooled primary heat exchanger, the condensed oil and uncondensed combustible gas enter a primary gas-liquid separation tank to realize oil-gas separation, and pyrolysis oil is collected and stored in a first oil tank;
oil gas generated by the third-stage cracking reaction furnace firstly passes through a second basket filter to remove solid ash in the oil gas, then enters a second-stage settling tower to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the second-stage settling tower, the uncondensed oil gas enters an air-cooling second-stage heat exchanger and then enters a water-cooling second-stage heat exchanger, most of oil in the oil gas is condensed out in the air-cooling second-stage heat exchanger and the water-cooling second-stage heat exchanger, the condensed oil and uncondensed combustible gas enter a second-stage gas-liquid separation tank to realize oil-gas separation, and the pyrolysis oil is collected and stored in a second oil tank;
and (V) combusting the non-condensable combustible gas: noncondensable combustible gas separated by the primary gas-liquid separation tank, the secondary gas-liquid separation tank and the tertiary gas-liquid separation tank is treated by a noncondensable combustible gas purifier and then returns to the combustor for combustion, and high-temperature flue gas is provided for the primary cracking reaction furnace, the secondary cracking reaction furnace and the tertiary cracking reaction furnace through the combustion chamber;
(VI) tail gas treatment: waste gas that the waste gas that produces and the waste gas that the burning of noncondensable combustible gas produced in the extrusion dryer dehydration process insert tail gas treatment module, get into and get rid of dust particulate matter in the filter-bag dust remover, then cool off in getting into the surface cooler, make vapor condense into liquid water and discharge, get into again and destroy waste gas molecular structure in the UV photocatalysis stove, reentrant activated carbon box adsorbs the pollutant, through the tail gas after the fan emission purifies at last.
The invention has the following advantages:
1. setting multi-stage cracking reaction temperature according to the types of various plastics in the mixed waste plastics, and realizing the independent cracking of each type of waste plastics in each cracking stage, thereby realizing the molecular bond controllable breakage based on temperature control and realizing the graded cracking of various plastics;
the chlorine-containing waste plastics (mainly PVC) can seriously corrode equipment and affect the quality of oil products, but because of the characteristics of PVC materials, the decomposition temperature is lowest, so the process can realize the preferential separation and cracking of the chlorine-containing waste plastics, the oil products are separately treated without sorting, and the online removal of chlorine-containing compounds is realized;
the invention realizes the independent recovery of various oil products, and can be independently applied according to the components of various plastic oil products, thereby improving the economic added value of the plastic oil products;
the invention realizes the sorting-free and cleaning-free of mixed plastics and avoids secondary pollution in the pretreatment process.
2. The invention develops an internal circulation method of a high enthalpy medium (namely, a coking ball preventing medium) in order to strengthen heat transfer and mass transfer in the cracking process of waste plastics, and mainly aims to add coking balls with different sizes and shapes in the cracking process and strengthen the heat transfer effect in the cracking process.
3. The decomposed oil gas is condensed and recovered in stages, and the condensed parts at all stages realize the separation of oil and gas and the collection of oil products through the working procedures of solid settlement, condensation, gas-liquid separation and the like.
4. The invention heats all stages of cracking reactors by high-temperature flue gas, and controls the temperature of all stages of cracking reactors by controlling the discharge capacity of the fan; and the flue gas after being utilized is recycled, so that the energy consumption is reduced.
Drawings
Fig. 1 is a schematic diagram of the arrangement of the system of the present invention.
Detailed Description
The present invention will be further described with reference to the following specific examples.
A mixed waste plastic industrial continuous classified cracking system comprises an extrusion dryer 1, a first-stage lifting screw conveyor 2, a catalytic mixing cylinder 3, a second-stage lifting screw conveyor 4, a semi-plasticizing feeder 5, a first-stage cracking reaction furnace 6, a second-stage cracking reaction furnace 7, a third-stage cracking reaction furnace 8, a slag discharge first-stage screw 9, a slag discharge second-stage screw 10, a slag discharge third-stage screw 11, a slag storage tank 12, a separator 13, a first basket filter 141, a second basket filter 142, a third basket filter 143, a first-stage settling tower 15, an air-cooled first-stage heat exchanger 16, a water-cooled first-stage heat exchanger 17, a first-stage gas-liquid separation tank 18, a second-stage settling tower 19, an air-cooled second-stage heat exchanger 20, a water-cooled second-stage heat exchanger 21, a second-stage gas-liquid separation tank 22, a third-stage settling tower 23, an air-cooled, A first oil tank 271, a second oil tank 272, a third oil tank 273, a noncondensable fuel gas purifier 28, an exhaust gas treatment module 29, a combustion chamber 30 and a combustion engine 31;
the plastic outlet of the extrusion dryer 1 is connected with the plastic inlet of the first-level lifting screw conveyor 2, the plastic outlet of the first-level lifting screw conveyor 2 is connected with the plastic inlet of the catalytic mixing cylinder 3, the plastic outlet of the catalytic mixing cylinder 3 is connected with the plastic inlet of the second-level lifting screw conveyor 4, the plastic outlet of the second-level lifting screw conveyor 4 is connected with the plastic inlet of the semi-plasticizing feeder 5, the plastic outlet of the semi-plasticizing feeder 5 is connected with the plastic inlet of the first-level cracking reaction furnace 6, the plastic outlet of the first-level cracking reaction furnace 6 is connected with the plastic inlet of the second-level cracking reaction furnace 7, the plastic outlet of the second-level cracking reaction furnace 7 is connected with the plastic inlet of the third-level cracking reaction furnace 8, the slag outlet of the third-level cracking reaction furnace 8 is connected with the slag inlet of the separator 13, the anti-coking ball outlet of the separator 13 is connected with the anti-coking ball inlet of the, the slag outlet of the separator 13 is connected with the slag inlet of the slag-discharging primary screw 9, the slag outlet of the slag-discharging primary screw 9 is connected with the slag inlet of the slag-discharging secondary screw 10, the slag outlet of the slag-discharging secondary screw 10 is connected with the slag inlet of the slag-discharging tertiary screw 11, and the slag outlet of the slag-discharging tertiary screw 11 is connected with the slag inlet of the slag storage tank 12;
the waste gas outlet of the first-stage cracking reaction furnace 6, the waste gas outlet of the second-stage cracking reaction furnace 7, the waste gas outlet of the third-stage cracking reaction furnace 8 and the waste gas outlet of the extrusion dryer 1 are all connected with a waste gas inlet of a tail gas treatment module 29, and the tail gas treatment module 29 comprises a filter bag dust collector, a surface cooler, a UV (ultraviolet) photo-catalytic furnace and an activated carbon box;
an oil gas outlet of the first-stage cracking reaction furnace 6 is connected with an oil gas inlet of a third basket filter 143, an oil gas outlet of the third basket filter 143 is connected with an oil gas inlet of a third-stage settling tower 23, an oil liquid outlet of the third-stage settling tower 23 is connected with an oil liquid inlet of a third oil tank 273, an oil gas outlet of the third-stage settling tower 23 is connected with an oil gas inlet of an air-cooled third-stage heat exchanger 24, an oil gas outlet of the air-cooled third-stage heat exchanger 24 is connected with an oil gas inlet of a water-cooled third-stage heat exchanger 25, an oil gas outlet of the water-cooled third-stage heat exchanger 25 is connected with an oil gas inlet of a third-stage gas-liquid separation tank 26;
an oil gas outlet of the secondary cracking reaction furnace 7 is connected with an oil gas inlet of a first basket filter 141, an oil gas outlet of the first basket filter 141 is connected with an oil gas inlet of a primary settling tower 15, an oil liquid outlet of the primary settling tower 15 is connected with an oil liquid inlet of an oil tank 27, an oil gas outlet of the primary settling tower 15 is connected with an oil gas inlet of an air-cooled primary heat exchanger 16, an oil gas outlet of the air-cooled primary heat exchanger 16 is connected with an oil gas inlet of a water-cooled primary heat exchanger 17, an oil gas outlet of the water-cooled primary heat exchanger 17 is connected with an oil gas inlet of a primary gas-liquid separation tank 18, and an oil liquid outlet of the primary gas-liquid separation tank 18 is connected with an;
an oil gas outlet of the third-stage cracking reaction furnace 8 is connected with an oil gas inlet of a second basket filter 142, an oil gas outlet of the second basket filter 142 is connected with an oil gas inlet of a second-stage settling tower 19, an oil liquid outlet of the second-stage settling tower 19 is connected with an oil liquid inlet of the oil tank 27, an oil gas outlet of the second-stage settling tower 19 is connected with an oil gas inlet of an air-cooling second-stage heat exchanger 20, an oil gas outlet of the air-cooling second-stage heat exchanger 20 is connected with an oil gas inlet of a water-cooling second-stage heat exchanger 21, an oil gas outlet of the water-cooling second-stage heat exchanger 21 is connected with an oil gas inlet of a second-stage gas-liquid separation tank 22;
the non-condensable gas outlet of the primary gas-liquid separation tank 18, the non-condensable gas outlet of the secondary gas-liquid separation tank 22, the non-condensable gas outlet of the tertiary gas-liquid separation tank 26, the non-condensable gas outlet of the first oil tank 271, the non-condensable gas outlet of the second oil tank 272 and the non-condensable gas outlet of the third oil tank 273 are connected in parallel and then connected with the non-condensable gas inlet of the non-condensable gas purifier 28, the non-condensable gas outlet of the non-condensable gas purifier 28 is connected with the non-condensable gas inlet of the burner 31, the natural gas outlet of the natural gas supply station 32 is connected with the natural gas inlet of the burner 31, the burner 31 is fixed on the combustion chamber 30, and a high-temperature flue gas outlet of the combustion chamber 30 is connected with a high-temperature flue gas inlet of the first-stage cracking reaction furnace 6, a high-temperature flue gas inlet of the second-stage cracking reaction furnace 7 and a high-temperature flue gas inlet of the third-stage cracking reaction furnace 8.
The furnace bodies of the first-stage cracking reaction furnace 6, the second-stage cracking reaction furnace 7 and the third-stage cracking reaction furnace 8 are all surrounded by refractory bricks and covered with heat-insulating materials for heat preservation.
And the outer jackets of the deslagging primary screws 9 are provided with circulating water cooling structures.
And a jacket heat-insulating structure is arranged on a pipeline between the non-condensable gas outlet of the non-condensable gas purifier 28 and the non-condensable gas inlet of the combustor 31.
And a pipeline between an oil gas outlet of the first-stage cracking reaction furnace 6 and an oil gas inlet of the third basket filter 143, a pipeline between an oil gas outlet of the second-stage cracking reaction furnace 7 and an oil gas inlet of the first basket filter 141, and a pipeline between an oil gas outlet of the third-stage cracking reaction furnace 8 and an oil gas inlet of the second basket filter 142 are all made of 316L stainless steel.
An industrial continuous classified cracking process for mixed waste plastics comprises the following steps:
dehydrating and preplasticizing: the extrusion dryer 1, the primary lifting screw conveyor 2, the catalytic mixing cylinder 3, the secondary lifting screw conveyor 4 and the semi-plasticizing feeder 5 are heated to 100-150 ℃ by infrared heating, mixed waste plastics firstly enter the extrusion dryer 1, the waste plastics are dehydrated under the extrusion action of a dehydration screw in the extrusion dryer 1, the dehydrated waste plastics are conveyed into the catalytic mixing cylinder 3 by the primary lifting screw conveyor 2, and the extruded waste plastics enter the catalytic mixing cylinder 3 and can be instantly opened and fluffy, so that the moisture which is not removed in the extrusion process is released; simultaneously, the catalyst is added into the catalytic mixing cylinder, the mixed waste plastic and the catalyst are uniformly mixed under the action of the conical screw of the catalytic mixing cylinder 3, then the mixed waste plastic enters a semi-plasticizing feeder 5 through a secondary lifting screw conveyor 4, the waste plastic is converted into a semi-plasticizing state through temperature rise and enters a primary cracking reaction furnace 6 together with an anti-coking ball; wherein the anti-coking balls are ceramic particles with particle sizes of 10-35 mm and different shapes;
(II) pyrolysis according to the types: in the earlier stage of the cracking reaction, supplying heat for a first-stage cracking reaction furnace 6, a second-stage cracking reaction furnace 7 and a third-stage cracking reaction furnace 8 by using outsourced natural gas and generating high-temperature flue gas at 1000-1200 ℃ after combustion by a combustor 31; wherein the cracking temperature of the primary cracking reaction furnace 6 is controlled to be 300-350 ℃ through the fan amount, so that the cracking of PVC plastics in the mixed waste plastics is realized; controlling the cracking temperature of the secondary cracking reaction furnace 7 to be 400-450 ℃ through the fan amount, and cracking PP and PE plastics in the mixed waste plastics; controlling the cracking temperature of the three-stage cracking reaction furnace 8 to be 500-550 ℃ through the fan opening, and cracking ABS plastics in the mixed waste plastics;
(III) deslagging: carbon black and anti-coking balls generated by pyrolysis of the third-stage pyrolysis furnace 8 firstly enter a separator 13, the anti-coking balls separated by the separator 13 return to the first-stage pyrolysis reaction furnace 6, the carbon black separated by the separator 13 enters a slag-discharging first-stage screw 9, enters a slag-discharging second-stage screw 10 under the lifting of the slag-discharging first-stage screw 9, continues to lift to a slag-discharging third-stage screw 11, and is sent to a slag storage tank 12 for storage after being cooled;
(IV) oil gas recovery: oil gas generated by the first-stage cracking reaction furnace 6 firstly passes through a third basket filter 143 to remove solid ash in the oil gas, then enters a third-stage settling tower 23 to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the third-stage settling tower 23, the oil gas which is not condensed enters an air-cooled third-stage heat exchanger 24 and then enters a water-cooled third-stage heat exchanger 25, most of oil in the oil gas is condensed out in the air-cooled third-stage heat exchanger 24 and the water-cooled third-stage heat exchanger 25, the condensed oil and non-condensed combustible gas enter a third-stage gas-liquid separation tank 26 to realize oil-gas separation, and pyrolysis oil is collected and stored in a third oil tank;
oil gas generated by the secondary cracking reaction furnace 7 firstly passes through the first basket filter 141 to remove solid ash in the oil gas, then enters the primary settling tower 15 to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the primary settling tower 15, the oil gas which is not condensed enters the air-cooled primary heat exchanger 16 and then enters the water-cooled primary heat exchanger 17, most of oil in the oil gas is condensed in the air-cooled primary heat exchanger 16 and the water-cooled primary heat exchanger 17, the condensed oil and non-condensed combustible gas enter the primary gas-liquid separation tank 18 to realize oil-gas separation, and the pyrolysis oil is collected and stored in the first oil tank 271;
oil gas generated by the third-stage cracking reaction furnace 8 firstly passes through the second basket filter 142 to remove solid ash in the oil gas, then enters the second-stage settling tower 19 to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the second-stage settling tower 19, the oil gas which is not condensed enters the air-cooled second-stage heat exchanger 20 and then enters the water-cooled second-stage heat exchanger 21, most of oil in the oil gas is condensed out in the air-cooled second-stage heat exchanger 20 and the water-cooled second-stage heat exchanger 21, the condensed oil and non-condensed combustible gas enter the second-stage gas-liquid separation tank 22 to realize oil-gas separation, and the pyrolysis oil is collected and stored in the second oil;
and (V) combusting the non-condensable combustible gas: noncondensable combustible gas separated by the primary gas-liquid separation tank 18, the secondary gas-liquid separation tank 22 and the tertiary gas-liquid separation tank 26 is treated by a noncondensable combustible gas purifier 28 and then returns to the combustor 31 for combustion, and high-temperature flue gas is provided for the primary cracking reaction furnace 6, the secondary cracking reaction furnace 7 and the tertiary cracking reaction furnace 8 through the combustion chamber 30;
(VI) tail gas treatment: waste gas that the waste gas that produces and the waste gas that the burning of noncondensable combustible gas produced among the extrusion dryer 1 dehydration process insert tail gas treatment module 29, get into and get rid of the dust particulate matter in the filter-bag dust remover, then cool off in getting into the surface cooler, make vapor condense into liquid water and discharge, get into again and destroy waste gas molecular structure in the UV photocatalysis stove, reentrant activated carbon box adsorbs the pollutant, through the tail gas after the fan emission purifies at last.
If the mixed waste plastics contain special waste plastics with higher cracking temperature, such as engineering plastics, a four-stage cracking reaction furnace is required to be added, the cracking temperature of the four-stage cracking reaction furnace is controlled to be 700-750 ℃ through the fan opening, and the cracking of the special plastics in the mixed plastics is realized, so that the requirement of cracking the mixed plastics according to the types is met.
In the dehydration preplasticizing step of the invention, the mixed waste plastics can be the separated waste plastics in the domestic garbage or the waste plastics in the stale garbage dug out in the garbage factory, the mixed plastics are primarily treated and then sent into a cracking reaction dehydration drying device, and the dehydration softening pretreatment equipment mainly comprises an extrusion drying machine 1, a primary lifting screw conveyor 2, a catalytic mixing material cylinder 3, a secondary lifting screw conveyor 4 and a semi-plasticizing feeding machine 5. After the waste plastics added into the feeding port enter the dehydration extruder 1, most of liquid water is removed through the extrusion action of a dehydration screw in the dehydration extruder 1; the tail end of the dehydration extruder 1 is provided with a rotary cutter head which can cut waste plastics into pieces, the pieces of waste plastics fall into a storage bin of the dehydration extruder 1 and are fluffy instantly, so that moisture which is not removed in the waste plastics overflows, the pieces of waste plastics are conveyed to a catalytic mixing material cylinder 3 under the action of a first-level lifting screw conveyor 2, catalysts such as ZSM-5 type molecular sieve, Y type molecular sieve, mordenite, viscous clay or metal oxide and the like can be added into the catalytic mixing material cylinder 3, and then the pieces of waste plastics are lifted to a hopper of a semi-plasticizing feeder 5 through a second-level lifting screw conveyor 4, and a semi-plasticizing process is carried out in the semi-plasticizing feeder 5 to prepare for subsequent thermal cracking. Liquid water extruded from the waste plastics is discharged into an external collecting device through a machine barrel drain hole, a machine head drain tank and a machine head conveying pipe drain hole through a drain passage, and gaseous water is discharged from an exhaust pipe through an exhaust net and enters a tail gas treatment module 29 for treatment. The process combines high-compression water squeezing and reinforced drying, has good dehydration effect, is energy-saving and environment-friendly, and has good application prospect.
Wherein, the dewatering screw of the extrusion dryer 1 adopts the equidistant deepening design, the front and back compression ratio of the screw is larger, and the better dewatering effect can be realized.
In the step of fractional pyrolysis, the fractional pyrolysis of the waste plastics is the core part of the process, the cracking characteristics of the waste plastics are different mainly through different compositions of organic molecular chains of the waste plastics, so that the cracking initial temperature, the cracking maximum weight loss rate temperature and the like of the waste plastics are different, and the cracking temperatures of different areas are set according to the characteristics of the materials, so that the single cracking is realized.
The waste plastics are dehydrated and then enter a molten state, and then enter a primary cracking reaction furnace 6, wherein the cracking temperature is generally 300-350 ℃, and the plastics with lower decomposition temperature, such as PVC, begin to crack, so that the independent treatment of chlorine-containing plastics can be realized; under the pushing action of double helix, the material enters a secondary cracking reaction furnace 7 through a primary cracking reaction furnace 6, the cracking temperature is set to be 400-450 ℃, the temperature range is mainly the decomposition of long-chain macromolecular compounds such as PP, PE and the like, the oil gas component generated by cracking in the temperature range is higher, and the component of the cracked oil product is relatively complex; waste plastics enter a third-level cracking reaction furnace 8 after passing through a second-level cracking reaction furnace 7, the cracking temperature is set to be 550-650 ℃, the cracking temperature of the waste plastics is higher, the waste plastics mainly undertake the cracking of engineering plastics such as ABS and the like, the oil component produced by the waste plastics is lower, the cracking gas component is higher, and the energy supply in the cracking process is undertaken by the first-level reaction kettle;
the number and the cracking temperature of the pyrolysis furnaces are determined according to the types of the mixed waste plastics in the cracking process, and if special plastics exist in the mixed plastics, the number of reaction kettles is additionally increased and the cracking temperature of the last stage is increased.
In the step of the staged pyrolysis, the anti-coking balls and the waste plastics enter the primary cracking reaction furnace 6 for cracking, then enter the secondary cracking reaction furnace 7 and the tertiary cracking reaction furnace 8 in sequence, are mixed and stirred, improve the uniformity of cracking, and simultaneously repeatedly rub and rub the wall surface of the cracker and the sector surface of the screw, remove coking, prevent coking and ensure continuous and stable operation of the cracking process.
Cracking ash and anti-coking balls formed by cracking waste plastics enter a cylinder of the separator, the anti-coking balls rub with each other under the stirring action of a screw rod of the separator, so that the cracking ash attached to the anti-coking balls is separated and discharged from an ash outlet, and the cleaned anti-coking balls are driven by a lifter screw rod to enter the primary cracking reaction furnace 6 again for automatic recycling through an anti-coking ball outlet, so that the automatic separation of the cracking ash formed by the anti-coking balls and the waste plastics is realized.
In the deslagging step of the invention, high-temperature cracking carbon particles are left after the waste plastics are cracked, and the continuous output and storage of the high-temperature cracking carbon particles are the key of the continuous operation of the whole set of cracking equipment. The process mainly adopts a water-cooled multistage spiral conveying and discharging system which is formed by connecting a slag discharging primary spiral 9, a slag discharging secondary spiral 10, a slag discharging tertiary spiral 11 and a slag storage tank 12 in series, has the characteristics of strong conveying capacity, good cooling effect, large storage capacity, good sealing property, stable operation and the like, and is suitable for collecting, cooling, conveying and storing various loose materials.
In the oil gas recovery step of the invention, the cracked oil product is the main product of the cracking of the waste plastics, and accounts for about 60 percent. At present, the cracking oil is recovered and treated in a centralized way in waste plastic cracking equipment at home and abroad, the quality of the oil product has larger difference along with the change of cracking process conditions, the quality stability is poorer, the post-treatment cost is higher, and the economic benefit of directly using the oil product as fuel oil is not high.
Different components of the waste plastic have different initial cracking temperatures and different cracking intervals in the cracking process, and the cracking temperatures are selectively set according to the components of the waste plastic, so that the separate recovery of the cracked oil products of the different plastic components is realized, and the maximum economic benefit of the cracked oil products can be realized; the influence of the chlorine content in PVC components in waste plastics on the quality of a cracked oil product can be solved, the cracked oil gas generated by reaction kettles at all stages needs to be independently recovered, solid ash in the cracked oil gas is mainly removed by a basket filter, then the cracked oil gas enters a settling tower to further remove the solid ash in the oil gas, components with larger molecular chains can be condensed in the settling tower, the oil gas which is not condensed enters a heat exchanger complete device, the device adopts two cooling modes of air cooling and water cooling, most of oil in the oil gas is condensed out in the heat exchanger complete device, and the condensed oil and the non-condensable gas enter a gas-liquid separation tank to realize oil-gas separation; finally, the non-condensable gas generated by the three sets of oil gas recovery devices is converged by the non-condensable gas purification device and then returns to the combustion furnace for combustion so as to provide heat energy for the system; pyrolysis oil generated by condensation of each stage of pyrolysis furnace is independently collected and stored in the oil tank, so that the chlorine content in subsequent pyrolysis oil is reduced, and oil recovery is realized.
In the step of burning the non-condensable combustible gas and recycling the waste heat, in the continuous cracking process, the used flue gas which is still at high temperature is sent to a burner to be heated slightly and then is circulated to the primary cracking reaction furnace 6, the secondary cracking reaction furnace 7 and the tertiary cracking reaction furnace 8 again, so that the required heat is provided for the cracking of the waste plastics, the fuel consumption is reduced, and the emission of the flue gas is reduced. At present, high-temperature flue gas for heating and cracking waste plastics is generally directly discharged to the atmosphere through a cracker, and the mode not only pollutes the environment, but also wastes a large amount of flue gas waste heat, thereby causing energy waste.
In the tail gas treatment step of the invention, the tail gas comprises two parts, one part is waste gas generated in the dehydration process in a conveying way, and the other part is waste gas generated in the combustion of non-condensable combustible gas. The main reason for generating pollutants in tail gas after combustion of the non-condensable combustible gas is incomplete combustion of the non-condensable combustible gas, and the pollutant components comprise dust particles and SO2、NOXHCl, benzopyrene, benzene, non-methane total hydrocarbons, and the like. In the tail gas treatment process, two kinds of waste gases are introduced into the filter bag dust remover together to remove dust particles, then the waste gases enter the surface air cooler to be cooled, so that water vapor is condensed into liquid water and is discharged, the saturation of the water in the gas is higher at the moment, and therefore a small part of tail gas is separated from the combustion tail gas and is mixed with the gas after dust removal and cooling in the mixing tank, the gas temperature is increased, and the water saturation in the gas is reduced. And the mixed gas enters the UV photocatalytic furnace to destroy the molecular structure of the waste gas, then enters the activated carbon box to adsorb pollutants, and finally the purified tail gas is discharged through the fan.

Claims (6)

1. An industrial continuous classified cracking system for mixed waste plastics is characterized in that: the device comprises an extrusion dryer (1), a first-stage lifting screw conveyor (2), a catalytic mixing material cylinder (3), a second-stage lifting screw conveyor (4), a semi-plasticizing feeder (5), a first-stage cracking reaction furnace (6), a second-stage cracking reaction furnace (7), a third-stage cracking reaction furnace (8), a slag-discharging first-stage screw (9), a slag-discharging second-stage screw (10), a slag-discharging third-stage screw (11), a slag storage tank (12), a separator (13), a first basket filter (141), a second basket filter (142), a third basket filter (143), a first-stage settling tower (15), an air-cooling first-stage heat exchanger (16), a water-cooling first-stage heat exchanger (17), a first-stage gas-liquid separation tank (18), a second-stage settling tower (19), an air-cooling second-stage heat exchanger (20), a water-cooling second-stage heat exchanger (21), a second, The system comprises an air-cooled three-stage heat exchanger (24), a water-cooled three-stage heat exchanger (25), a three-stage gas-liquid separation tank (26), a first oil tank (271), a second oil tank (272), a third oil tank (273), a non-condensable gas purifier (28), a tail gas treatment module (29), a combustion chamber (30) and a burner (31);
the plastic outlet of the extrusion dryer (1) is connected with the plastic inlet of a first-level lifting screw conveyor (2), the plastic outlet of the first-level lifting screw conveyor (2) is connected with the plastic inlet of a catalytic mixing cylinder (3), the plastic outlet of the catalytic mixing cylinder (3) is connected with the plastic inlet of a second-level lifting screw conveyor (4), the plastic outlet of the second-level lifting screw conveyor (4) is connected with the plastic inlet of a semi-plasticizing feeder (5), the plastic outlet of the semi-plasticizing feeder (5) is connected with the plastic inlet of a first-level cracking reaction furnace (6), the plastic outlet of the first-level cracking reaction furnace (6) is connected with the plastic inlet of a second-level cracking reaction furnace (7), the plastic outlet of the second-level cracking reaction furnace (7) is connected with the plastic inlet of a third-level cracking reaction furnace (8), and the slag outlet of the third-level cracking reaction furnace (8) is connected with the slag inlet of a separator (13), an outlet of a coking-prevention ball of the separator (13) is connected with an inlet of a coking-prevention ball of the first-level cracking reaction furnace (6), a slag outlet of the separator (13) is connected with a slag inlet of the deslagging first-level spiral (9), a slag outlet of the deslagging first-level spiral (9) is connected with a slag inlet of the deslagging second-level spiral (10), a slag outlet of the deslagging second-level spiral (10) is connected with a slag inlet of the deslagging third-level spiral (11), and a slag outlet of the deslagging third-level spiral (11) is connected with a slag inlet of the slag storage tank (12);
the waste gas outlet of the first-stage cracking reaction furnace (6), the waste gas outlet of the second-stage cracking reaction furnace (7), the waste gas outlet of the third-stage cracking reaction furnace (8) and the waste gas outlet of the extrusion dryer (1) are all connected with the waste gas inlet of a tail gas treatment module (29), and the tail gas treatment module (29) comprises a filter bag dust remover, a surface cooler, a UV (ultraviolet) photocatalysis furnace and an activated carbon box;
an oil gas outlet of the first-stage cracking reaction furnace (6) is connected with an oil gas inlet of a third basket filter (143), an oil gas outlet of the third basket filter (143) is connected with an oil gas inlet of a third-stage settling tower (23), an oil liquid outlet of the third-stage settling tower (23) is connected with an oil liquid inlet of a third oil tank (273), an oil gas outlet of the third-stage settling tower (23) is connected with an oil gas inlet of an air-cooled third-stage heat exchanger (24), an oil gas outlet of the air-cooled third-stage heat exchanger (24) is connected with an oil gas inlet of a water-cooled third-stage heat exchanger (25), an oil gas outlet of the water-cooled third-stage heat exchanger (25) is connected with an oil gas inlet of a third-stage gas-liquid separation tank (26), and an oil liquid outlet of the third-liquid;
an oil gas outlet of the secondary cracking reaction furnace (7) is connected with an oil gas inlet of a first basket filter (141), an oil gas outlet of the first basket filter (141) is connected with an oil gas inlet of a first-stage settling tower (15), an oil liquid outlet of the first-stage settling tower (15) is connected with an oil liquid inlet of an oil tank (27), an oil gas outlet of the first-stage settling tower (15) is connected with an oil gas inlet of an air-cooled first-stage heat exchanger (16), an oil gas outlet of the air-cooled first-stage heat exchanger (16) is connected with an oil gas inlet of a water-cooled first-stage heat exchanger (17), an oil gas outlet of the water-cooled first-stage heat exchanger (17) is connected with an oil gas inlet of a first-stage gas-liquid separation tank (18), and an oil liquid outlet of the first-liquid separation;
an oil gas outlet of the third-stage cracking reaction furnace (8) is connected with an oil gas inlet of a second basket filter (142), an oil gas outlet of the second basket filter (142) is connected with an oil gas inlet of a second-stage settling tower (19), an oil liquid outlet of the second-stage settling tower (19) is connected with an oil liquid inlet of the oil tank (27), an oil gas outlet of the second-stage settling tower (19) is connected with an oil gas inlet of an air-cooling second-stage heat exchanger (20), an oil gas outlet of the air-cooling second-stage heat exchanger (20) is connected with an oil gas inlet of a water-cooling second-stage heat exchanger (21), an oil gas outlet of the water-cooling second-stage heat exchanger (21) is connected with an oil gas inlet of a second-stage gas-liquid separation tank (22), and an oil liquid outlet of the second-;
the noncondensable combustible gas outlet of the primary gas-liquid separation tank (18), the noncondensable combustible gas outlet of the secondary gas-liquid separation tank (22), the noncondensable combustible gas outlet of the tertiary gas-liquid separation tank (26), the noncondensable combustible gas outlet of the first oil tank (271), the noncondensable combustible gas outlet of the second oil tank (272) and the noncondensable combustible gas outlet of the third oil tank (273) are connected in parallel and then connected with the noncondensable combustible gas inlet of the noncondensable combustible gas purifier (28), the noncondensable combustible gas outlet of the noncondensable combustible gas purifier (28) is connected with the noncondensable combustible gas inlet of the burner (31), the natural gas outlet of the natural gas supply station (32) is connected with the natural gas inlet of the burner (31), the burner (31) is fixed on the combustion chamber (30), and the high-temperature flue gas outlet of the combustion chamber (30) is connected with the high-temperature flue gas inlet of the primary cracking reaction furnace (6), the high-temperature flue gas inlet of the secondary cracking reaction furnace (7) and the high-temperature flue gas And (6) connecting.
2. The industrial continuous classified cracking system of mixed waste plastics according to claim 1, characterized in that: the furnace bodies of the first-stage cracking reaction furnace (6), the second-stage cracking reaction furnace (7) and the third-stage cracking reaction furnace (8) are all surrounded by refractory bricks and covered with heat-insulating materials for heat preservation.
3. The industrial continuous classified cracking system of mixed waste plastics according to claim 1, characterized in that: and the outer jackets of the deslagging primary screws (9) are provided with circulating water cooling structures.
4. The industrial continuous classified cracking system of mixed waste plastics according to claim 1, characterized in that: and a jacket heat insulation structure is arranged on a pipeline between a non-condensable combustible gas outlet of the non-condensable combustible gas purifier (28) and a non-condensable combustible gas inlet of the combustor (31).
5. The industrial continuous classified cracking system of mixed waste plastics according to claim 1, characterized in that: and a pipeline between an oil gas outlet of the first-stage cracking reaction furnace (6) and an oil gas inlet of the third basket filter (143), a pipeline between an oil gas outlet of the second-stage cracking reaction furnace (7) and an oil gas inlet of the first basket filter (141), and a pipeline between an oil gas outlet of the third-stage cracking reaction furnace (8) and an oil gas inlet of the second basket filter (142) are all made of 316L stainless steel.
6. An industrial continuous classified cracking process for mixed waste plastics, which is characterized in that: the method comprises the following steps: dehydrating and preplasticizing: the extrusion dryer (1), the primary lifting screw conveyor (2), the catalytic mixing cylinder (3), the secondary lifting screw conveyor (4) and the semi-plasticizing feeder (5) are heated to 100-150 ℃ by infrared heating, mixed waste plastics firstly enter the extrusion dryer (1), the waste plastics are dehydrated under the extrusion action of a dehydration screw in the extrusion dryer (1), the dehydrated waste plastics are conveyed into the catalytic mixing cylinder (3) by the primary lifting screw conveyor (2), and the extruded waste plastics enter the catalytic mixing cylinder (3) to be instantly opened and fluffy, so that the moisture which is not removed in the extrusion process is released; simultaneously, the catalyst is added into the catalytic mixing cylinder, the mixed waste plastic and the catalyst are uniformly mixed under the action of a conical screw of the catalytic mixing cylinder (3), then the mixed waste plastic and the catalyst enter a semi-plasticizing feeder (5) through a secondary lifting screw conveyor (4), the waste plastic is converted into a semi-plasticizing state through temperature rise and enters a primary cracking reaction furnace (6) together with an anti-coking ball;
(II) pyrolysis according to the types: in the early stage of the cracking reaction, supplying heat for a first-stage cracking reaction furnace (6), a second-stage cracking reaction furnace (7) and a third-stage cracking reaction furnace (8) by using outsourced natural gas and generating high-temperature flue gas at 1000-1200 ℃ after combustion by a combustor (31); wherein the cracking temperature of the primary cracking reaction furnace (6) is controlled to be 300-350 ℃ through the fan amount, so that the cracking of PVC plastics in the mixed waste plastics is realized; controlling the cracking temperature of the secondary cracking reaction furnace (7) to be 400-450 ℃ through the fan amount, and realizing the cracking of PP and PE plastics in the mixed waste plastics; controlling the cracking temperature of the three-stage cracking reaction furnace (8) to be 500-550 ℃ through the fan opening, and cracking ABS plastics in the mixed waste plastics;
(III) deslagging: carbon black and anti-coking balls generated by pyrolysis of the three-stage pyrolysis furnace (8) firstly enter a separator (13), the anti-coking balls separated by the separator (13) return to the first-stage pyrolysis reaction furnace (6), the carbon black separated by the separator (13) enters a deslagging first-stage spiral (9), enters a deslagging second-stage spiral (10) under the lifting of the deslagging first-stage spiral (9), then continues to lift to a deslagging third-stage spiral (11), and is cooled and then sent to a slag storage tank (12) through the deslagging third-stage spiral (11) for storage;
(IV) oil gas recovery: oil gas generated by the first-stage cracking reaction furnace (6) firstly passes through a third basket filter (143) to remove solid ash in the oil gas, then enters a third-stage settling tower (23) to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the third-stage settling tower (23), the oil gas which is not condensed enters an air-cooled third-stage heat exchanger (24) and then enters a water-cooled third-stage heat exchanger (25), most oil in the oil gas is condensed out in the air-cooled third-stage heat exchanger (24) and the water-cooled third-stage heat exchanger (25), the condensed oil and non-condensed combustible gas enter a third-stage gas-liquid separation tank (26) to realize oil-gas separation, and pyrolysis oil is collected and stored in a third oil tank (273;
oil gas generated by the secondary cracking reaction furnace (7) firstly passes through a first basket filter (141) to remove solid ash in the oil gas, then enters a primary settling tower (15) to further remove the solid ash in the oil gas, wherein components with larger molecular chains can be condensed in the primary settling tower (15), the oil gas which is not condensed enters an air-cooled primary heat exchanger (16) and then enters a water-cooled primary heat exchanger (17), most of oil in the oil gas is condensed out in the air-cooled primary heat exchanger (16) and the water-cooled primary heat exchanger (17), the condensed oil and uncondensed combustible gas enter a primary gas-liquid separation tank (18) to realize oil-gas separation, and pyrolysis oil is collected and stored in a first oil tank (271);
oil gas generated by the third-stage cracking reaction furnace (8) firstly passes through the second basket filter (142) to remove solid ash in the oil gas, then enters the second-stage settling tower (19) to further remove the solid ash in the oil gas, wherein components with larger molecular chains are also condensed in the second-stage settling tower (19), the oil gas which is not condensed enters the air-cooling second-stage heat exchanger (20) and then enters the water-cooling second-stage heat exchanger (21), most of oil in the oil gas is condensed out in the air-cooling second-stage heat exchanger (20) and the water-cooling second-stage heat exchanger (21), the condensed oil and non-condensed combustible gas enter the second-stage gas-liquid separation tank (22) to realize oil-gas separation, and pyrolysis oil is collected and stored in the second oil tank (;
and (V) combusting the non-condensable combustible gas: noncondensable combustible gas separated by the primary gas-liquid separation tank (18), the secondary gas-liquid separation tank (22) and the tertiary gas-liquid separation tank (26) is treated by a noncondensable combustible gas purifier (28) and then returns to the combustor (31) for combustion, and high-temperature flue gas is provided for the primary cracking reaction furnace (6), the secondary cracking reaction furnace (7) and the tertiary cracking reaction furnace (8) through the combustion chamber (30);
(VI) tail gas treatment: waste gas that the dehydration in-process of extrusion dryer (1) produced and the waste gas that the burning of noncondensable combustible gas produced access tail gas processing module (29), get into and get rid of the dust particulate matter in the filter-bag dust remover, then cool off in getting into the surface cooler, make vapor condense into liquid water and discharge, reentrant UV photocatalysis stove destroys waste gas molecular structure, reentrant activated carbon box adsorbs the pollutant, discharge the tail gas after purifying through the fan at last.
CN202011052638.1A 2020-09-29 2020-09-29 Industrial continuous classified cracking system and process for mixed waste plastics Pending CN112251251A (en)

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