CN113122300A - Process method and device for preparing oil by pyrolyzing high-molecular polymerization waste - Google Patents

Abstract

The invention discloses a process method and device for producing oil by pyrolysis of polymer polymer waste, which comprises the steps of extruding polymer polymer waste through an extruder and then mixing it with bed material and sending it to a fixed bed pyrolysis reactor for pyrolysis reaction, producing The high-temperature oil and gas are removed by the cyclone to exchange heat with nitrogen, and then enter the waste heat boiler to recover heat energy and separate from gas and liquid. The liquid is sent to the crude oil tank for storage, and the gas is further condensed to obtain crude oil; The oxygen-depleted hot air is generated by combustion in the generator and sent to the fixed-bed pyrolysis reactor to fully contact with the mixture to provide heat for the pyrolysis reaction; the waste residue is cooled and sieved, and the bed material is recovered and reused. The invention solves the corrosive problem caused by chlorine and acid gas generated by pyrolysis of the reaction system by dechlorinating and deacidifying the polymer polymerization waste after extrusion, and adopts a multi-stage heating method to ensure the pyrolysis temperature in the reactor. , to solve the problem of poor thermal conductivity of polymer polymerization waste and uneven heating of the reaction.

Description

Process method and device for preparing oil by pyrolyzing high-molecular polymerization waste

Technical Field

The invention relates to the technical field of high polymer waste treatment, in particular to a high polymer waste pyrolysis oil preparation process method and a pyrolysis oil preparation device.

Background

High molecular polymers are widely applied to our daily lives, such as polyethylene terephthalate (PETE), bottles generally used for making soft drinks, such as mineral water bottles, fruit juice bottles and the like, High Density Polyethylene (HDPE), used for making milk bottles, bath cream bottles, detergent bottles and the like, polyvinyl chloride, trays used for making candies and fruits, plastic packages, food preservative films and the like, Low Density Polyethylene (LDPE), used for making some bottles, shopping bags and high strength bags and some other packaging films, polypropylene (PP), used for making some inner liners and outer edge structures of home appliances, luggage, toys and vehicles, Polystyrene (PS), mainly used for making toys, hard packages, cosmetics and the like, high molecular polymer wastes (waste plastics, waste tires and the like) generated in daily lives bring great pressure to the environment due to difficult degradation thereof, the formed pollution becomes a great environmental pollution problem which needs to be treated urgently by human beings.

At present, the treatment of the high molecular polymerization waste at home and abroad mainly adopts the forms of landfill, incineration and heat energy recovery, melting regeneration, pyrolysis conversion and the like, wherein the pyrolysis conversion can convert the high molecular polymerization waste into an industrial raw material or fuel oil with a utilization value, not only can eliminate environmental pollution, but also can realize sustainable development and utilization of resources, is an effective way for treating white pollution, is considered as the most promising resource recovery method, and in recent years, the technology for refining the fuel oil by pyrolyzing the high molecular polymerization waste at home and abroad mainly comprises four modes of pyrolysis, catalytic cracking, pyrolysis-catalytic modification, catalytic cracking-catalytic modification.

The thermal cracking method is to put the high molecular polymerization waste into a pyrolysis reactor and directly heat under the condition of no oxygen or little oxygen to break C-C bonds and C-H bonds to obtain molecular hydrocarbons with different lengths, and the molecular hydrocarbons are further fractionated to obtain different types of fuel oil. Different types of polymer wastes have different thermal cracking temperatures, and the proportion of heavy oil obtained by a direct heating method is generally larger than that of light oil. The pyrolysis method has the advantages of higher reaction temperature, long reaction time, strict requirements on hardware facilities such as equipment and the like, low liquid oil yield, easy generation of paraffin and olefin in the reaction process, blockage of pipelines, poor product oil quality and low octane number, but the pyrolysis method has unique advantages and can also obtain good effect as long as proper process conditions and equipment are provided.

The catalytic cracking method is to mix a catalyst and high molecular polymerization waste and then put the mixture into a pyrolysis reactor to be heated and cracked to prepare liquid oil, wherein the catalyst used is usually a solid acid catalyst. Such catalysts are prone to H formation during the reaction⁺The pyrolysis reaction mechanism accords with the carbocation theory. Cracking the high molecular polymerization waste under the condition of high-temperature heating to generate long-carbon-chain olefin, and then obtaining H from the surface of the catalyst by the olefin⁺Forming carbonium ions, firstly breaking carbonium ions into primary and secondary carbonium ions, then isomerizing to form more stable tertiary carbonium ions, and finally making H be substituted by stable tertiary carbonium ions⁺Also given to the catalyst, itself becomes an olefin. The catalyst is a key technology for oil refining by catalytic cracking of the high molecular polymerization waste, and different catalysts have different process requirements and are important factors for limiting the development of the oil refining technology by catalytic cracking of the high molecular polymerization waste. The catalyst has the characteristics of reducing the reaction temperature, improving the reaction rate, shortening the reaction time, selectively isomerizing and aromatizing the product, improving the yield of liquid production and obtaining the gasoline with higher quality. However, in the reaction process, the catalyst and the raw materials are mixed together, and the surface of the catalyst is covered by silt and carbon slag generated by cracking in the macromolecular polymerization waste, so that the catalyst is easy to lose activity and is difficult to recover, thereby increasing the operation cost.

The pyrolysis catalytic modification method is a process of heating, melting and cracking the macromolecular polymerization waste into a gaseous state under an oxygen-free or oxygen-deficient state, and then introducing the pyrolysis gas into a catalytic tube filled with a catalyst for catalytic modification. In the catalytic modification process of the pyrolysis product, reactions such as alkane isomerization, ring structure, olefin aromatization and the like occur, so that the octane number of the gasoline fraction is improved. The heavy components in the thermal cracking products of the high molecular polymerization wastes are more, and the pyrolysis-catalytic modification can increase the light components in the fuel oil, reduce the heavy components and improve the quality of the fuel oil. Compared with thermal cracking catalyst, the catalyst has less modified catalyst consumption, can be recovered and reused, greatly reduces the cost, and is a popular process method at present.

The catalytic cracking-catalytic modifying method is that the high molecular polymerization waste and the catalyst are first placed in a pyrolysis reactor for pyrolysis and gasification, and then the pyrolysis gas is introduced into a catalytic tube for catalytic modification, and is the combination of catalytic pyrolysis and pyrolysis catalytic modification. The method integrates the advantages of two methods of catalytic pyrolysis and pyrolysis-catalytic modification, namely, the temperature required by the reaction is reduced, the reaction time is shortened, and meanwhile, high-quality product oil can be obtained. The catalytic cracking-catalytic modifying method has the outstanding advantages of overcoming the defects of high pyrolysis reaction temperature, low oil yield and the like, improving the pyrolysis efficiency of the high-molecular polymerization waste, saving energy and simultaneously obtaining high-quality gasoline and diesel oil. However, this method has the disadvantage that the catalyst is used in a large amount, which causes a series of process problems due to the catalyst and causes a high cost. There is a need to develop a cheap and efficient pyrolysis catalyst and a reforming catalyst for high molecular polymerization waste, thereby promoting the industrial process.

The prior art has various reactor forms, such as a spouted bed reactor, a falling fixed bed reactor, a fluidized bed reactor, an intermittent or semi-intermittent reaction kettle, a rotary kiln reactor, a screw pyrolysis reactor and the like, the reactor structure is complex, the method has the advantages that the adaptability to raw materials is not high, most reactors limit the PE and PVC content in high polymer waste, production devices in the prior art are small in processing treatment capacity, mostly produce in an intermittent or semi-intermittent mode, are low in continuous automation degree and low in industrial application degree, the prior art is developed by adopting the theme of catalysis, the direct catalytic pyrolysis and the secondary catalytic upgrading conversion of primary products of conventional pyrolysis need to be developed for high-performance catalysts, the catalyst consumption is high, a series of process problems caused by the catalysts can be generated, the cost is overhigh, the economic benefit is low, and therefore the technologies are not suitable for use.

It is believed that pyrolysis of the polymeric polymer waste occurs first as a depolymerization reaction of the polymer, followed by other complex secondary reactions. According to the literature report, under the condition of 500 ℃ and short residence time, the pyrolysis of the high molecular polymerization waste is easy to form wax substances, and the yield of oil is obviously improved along with the increase of the residence time; under the conditions of reaction temperature of 800 ℃ and short residence time, the high molecular polymerization waste can directly crack small molecular olefins.

Due to the different monomer structures of the polymers, there may also be differences in the corresponding pyrolysis products. For HDPE, LDPE and PP, the primary pyrolysis products are dominated by linear olefins and alkanes. In the case of PS, since the molecular structure thereof contains benzene rings, the primary pyrolysis product thereof is also an aromatic hydrocarbon substance. In the case of PETE (also sometimes referred to as PET), its molecular structure contains an ester functional group, and thus its pyrolysis product may contain oxygen-containing compounds such as acids and ketones. In the case of PVC, the molecular structure contains chlorine atoms, and thus HCl is a very typical pyrolysis product. HDPE, LDPE, PP and PS are ideal raw materials for pyrolysis, and the pyrolysis product is hydrocarbon which can be directly used as liquid fuel through further treatment or used as a raw material in the petrochemical refining industry. Therefore, in the existing pyrolysis engineering practice of the high molecular polymer waste, the materials are also selected and used as raw materials. The pyrolysis product of PETE contains acids, which not only affect the quality of the pyrolysis liquid product and the subsequent refining treatment thereof, but also cause the corrosion of the pyrolysis reactor. HCl generated by pyrolysis of PVC can form hydrochloric acid with strong corrosivity in the presence of water, and has strong corrosivity on a steel reaction system. Therefore, many practical polymer waste pyrolysis engineering projects place restrictions on the contents of PETE and PVC.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a process method and a device for preparing oil by pyrolyzing macromolecular polymerization wastes, which have the advantages of strong overall practicability and the like and solve the problem that the existing domestic and foreign treatment technology for macromolecular polymerization wastes has more defects.

The first aspect of the invention provides a process method for preparing oil by pyrolyzing polymeric wastes, which specifically comprises the following steps:

s1, extruding the high molecular polymerization waste by an extruder, and feeding the extruded material into a storage bin to be uniformly mixed with bed materials to obtain a mixture;

s2, feeding the mixture into a fixed bed pyrolysis reactor for pyrolysis reaction;

s3, after fly ash is removed from high-temperature oil gas generated by pyrolysis reaction through a cyclone separator, the high-temperature oil gas enters a nitrogen heat exchanger to exchange heat with nitrogen from an air preheater, the oil gas after heat exchange enters a waste heat boiler to recover heat energy, the oil gas enters a first gas-liquid separator to be subjected to gas-liquid separation, liquid is sent into a crude oil tank to be stored, the gas enters an oil gas condenser and a second gas-liquid separator to be further condensed to prepare crude oil, the crude oil is sent into the crude oil tank to be stored, non-condensable gas is sent to an inert gas generator to be used as auxiliary fuel, or tail gas is;

s4, sending part of the nitrogen after heat exchange into a fixed bed pyrolysis reactor as reaction protective gas, sending part of the nitrogen into an air preheater to exchange heat with air, sending the nitrogen into a nitrogen heat exchanger for recycling by a nitrogen circulating fan after heat exchange, and supplementing cold nitrogen when the nitrogen is insufficient; preheating air from an air preheater is fed into an inert gas generator to assist fuel combustion, fuel or noncondensable gas from a gas-liquid separator is combusted in the inert gas generator to generate oxygen-deficient hot air, and the oxygen-deficient hot air is fed into the fixed bed pyrolysis reactor and is fully contacted with a mixture to provide heat for the pyrolysis reaction;

s5, the solid slag discharged from the bottom of the fixed bed pyrolysis reactor mainly comprises bed materials and ash slag, the bed materials are recycled after being cooled by a cold slag tank and screened by a solid slag vibrating screen, the bed materials are returned to a storage bin for recycling, and the ash slag is sent to the outside for landfill disposal.

Preferably, a lower water tank is arranged below a discharge port of the extruder, the molten material falls into the water tank after being extruded, and forms irregular blocky materials under the chilling action of water, and the irregular blocky materials are sent into a storage bin after being crushed and screened.

As another preferred scheme, normal temperature air is sprayed into the homogenizing section of the extruder, water vapor in the molten material is blown out by wind, and the extruded material is in a loose particle state and is directly sent into a storage bin.

As another preferred scheme, low-pressure steam is injected into the homogenizing section of the extruder, the front end of the cylinder of the extruder is provided with a nozzle structure, and the extruded material is discharged in a liquid spray mode and is directly injected into a storage bin to be mixed with bed materials.

Preferably, the bed material is selected from at least one of alumina balls, porcelain balls, molecular sieves or fine sand.

Preferably, the weight ratio of the bed material to the extruded material is in the range of 1: 5 to 4: 5.

preferably, the pyrolysis reaction temperature of the step S2 is 400-700 ℃.

Preferably, the velocity of the air supplied to the fixed-bed pyrolysis reactor with the oxygen-depleted hot blast in step S4 is set to 0.2 to 0.5m/S, and the oxygen concentration of the oxygen-depleted hot blast is <30ppm, preferably <20 ppm.

Preferably, the slag cooling tank adopts a jacket water cooling mode, and the generated low-pressure steam is sent out for utilization.

Preferably, the oil gas condenser condenses the high-temperature oil gas by using circulating cooling water, the non-condensable gas is sent into a tail gas purification device, the non-condensable gas is purified by using dust removal, acid gas removal and denitrification technologies, and the purified tail gas is discharged to the outside.

The second aspect of the invention provides a device for preparing oil by pyrolyzing polymeric wastes, which comprises an extruder, wherein the bottom of the extruder is communicated with a crusher through a packing auger, the crusher is positioned above a raw material vibrating screen, a storage bin is positioned on the right side of the raw material vibrating screen and is communicated with the raw material vibrating screen through a pipeline, the bottom of the storage bin is communicated with a screw feeder, a fixed bed pyrolysis reactor is positioned under a discharge port at the right end of the screw feeder, an inert gas generator is positioned at the right side of the fixed bed pyrolysis reactor and is connected with the fixed bed pyrolysis reactor through a pipeline, a cyclone separator is positioned on the right upper side of the fixed bed pyrolysis reactor and is connected with the fixed bed pyrolysis reactor through a pipeline, a nitrogen heat exchanger and an air preheater are respectively positioned above and above the cyclone separator, the nitrogen heat exchanger and the air preheater are communicated with each other, the nitrogen heat exchanger and the cyclone separator are communicated through a pipeline, the air preheater is, the waste heat boiler and the first gas-liquid separator are respectively positioned above and above the nitrogen heat exchanger, the waste heat boiler is communicated with the nitrogen heat exchanger and the first gas-liquid separator through pipelines, the first gas-liquid separator is communicated with the crude oil tank through a pipeline, the oil-gas condenser is positioned above the first gas-liquid separator and is communicated with the first gas-liquid separator through a pipeline, the left lower part of the oil-gas condenser is communicated with the second gas-liquid separator through a pipeline, the tail gas purification device is communicated with the second gas-liquid separator, the lower parts of the first gas-liquid separator and the second gas-liquid separator are communicated with the crude oil tank, the cold slag tank is communicated with the bottom of the fixed bed pyrolysis reactor, and the bottom of the cold, the output end of the combustion-supporting fan is communicated with the right side of the air preheater, the output end of the nitrogen circulating fan is communicated with the right side of the nitrogen heat exchanger, and the high-temperature disc valve is fixedly installed at the bottom of the fixed bed pyrolysis reactor.

And a slag outlet at the bottom of the fixed bed pyrolysis reactor is provided with a high-temperature disc valve for controlling the slag discharging speed and ensuring the height of a bed layer in the reactor.

Preferably, the extruder is internally provided with three to ten chambers, the high polymer waste is gradually melted through the chambers in the temperature rising process, a water tank is arranged on the lower side of the outlet of the extruder, and the extruded material is chilled and cooled by water after falling into the water tank in a molten state to form a gray black solid extruded material which has certain strength and hardness and is used as a pyrolysis raw material.

Preferably, steam is introduced into two to four chambers of the extruder before discharging, the outlet of the extruder is modified into a nozzle and is directly connected to the stock bin, so that the high molecular polymer in the extruder at the moment is extruded into a liquid state, and the high molecular polymer is directly sprayed into the stock bin in a hot state to be mixed with bed materials to serve as raw materials.

Preferably, the upper parts of the chambers of the extruder are provided with gas collecting pipelines, waste gas generated in the process of melting and fusing the high molecular polymerization waste is collected, and the collected waste gas is further purified and then discharged. Preferably, the gas collecting pipeline adopts a multi-path gas extraction mode, an exhaust port is arranged above the middle part of each chamber, gas extracted from each exhaust port is connected to a main pipe through a pipeline and sent to a subsequent waste gas treatment unit, and the waste gas treatment unit adopts a small SCR denitration and alkali washing deacidification device to treat the collected extrusion waste gas so as to purify the extrusion waste gas to reach the emission standard and discharge the extrusion waste gas to the outside.

Preferably, pyrolysis gas generated by the fixed bed pyrolysis reactor contains ash, a cyclone separator is arranged, and the ash brought out along with oil gas is collected and sent back to the fixed bed pyrolysis reactor by hot air.

Compared with the prior art, the invention has the following beneficial effects:

1) according to the invention, by setting a double-feeding mode, the raw material can be a solid granular material or a liquid material after being extruded, and the feeding form is flexible and convenient.

2) The invention adopts a multi-section heat supply mode, adopts direct external heat supply, and respectively supplies heat to the upper section, the middle section and the lower section of the fixed bed pyrolysis reactor in multiple sections, thereby ensuring the pyrolysis temperature in the reactor, solving the problems of poor thermal conductivity of high polymer polymerization waste and uneven heating in reaction, improving the heat transfer efficiency and the utilization rate of heat energy, having multiple heat sources, and being capable of adopting hot air, hot nitrogen, steam and the like.

3) The invention is provided with a bed material system, fresh bed materials and solid particles or liquid materials are mixed in a raw material bin, the bed materials after reaction are cooled by a slag cooling tank, the solid slag is recovered after being screened and separated by a vibrating screen, and the bed materials are returned to the raw material bin for recycling.

4) HCl generated by pyrolysis of high molecular polymerization waste PVC can form hydrochloric acid with strong corrosivity in the presence of water, and has strong corrosivity on a steel reaction system, and a pyrolysis product of PETE contains acids, so that the quality of a pyrolysis liquid product and subsequent refining treatment of the pyrolysis liquid product can be influenced, and meanwhile, corrosion of a pyrolysis reactor can be caused.

5) According to the invention, hot air and hot nitrogen are directly contacted with the mixed raw material, on one hand, inert gas is used as reaction protective gas, on the other hand, heat is provided for pyrolysis reaction, and the reaction safety and stability are ensured while the reaction heat transfer efficiency is improved. The invention considers the integrated use of heat, and oxygen-poor hot air and hot nitrogen generated by the inert gas generator are sent into the normal-pressure fixed bed reactor to ensure the heat energy required by the pyrolysis reaction.

6) The heat energy of high-temperature oil gas is recovered by adopting a nitrogen heat exchanger and a waste heat boiler, the high-temperature oil gas exchanges heat with the nitrogen gas on one hand, on the other hand, steam is generated by the waste heat boiler, the hot nitrogen gas heats cold air through an air preheater, and the steam generated by the waste heat boiler and the steam generated by the cold slag tank are sent out for utilization; the waste heat boiler, the nitrogen heat exchanger and the air preheater are arranged, the heat energy of the system is recycled in multiple stages, the system is fully utilized, and the energy consumption and the operation cost are reduced.

7) The invention adopts a nitrogen circulating fan, hot nitrogen exchanging heat with high-temperature oil gas heats cold air through an air preheater, preheated air is sent to an inert gas generator to assist fuel combustion, low-temperature nitrogen from the air preheater is sent back to a nitrogen heat exchanger through the nitrogen circulating fan to exchange heat with the high-temperature oil gas, the nitrogen is recycled, and the insufficient part is supplemented by the cold nitrogen. The nitrogen is recycled, the system operation cost is greatly reduced, the hot air assists in combustion, the combustion efficiency is improved, and the fuel consumption is reduced.

8) The invention has the advantages of wide raw material application range, simple device structure, low equipment manufacturing cost, stable performance and low operation cost, and achieves the effect of strong overall practicability.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a process flow diagram of the present invention;

FIG. 3 is a schematic view of the extruder configuration of the present invention employing water-cooled discharge;

FIG. 4 is a schematic view of the extruder configuration of the present invention employing air-cooled discharge;

FIG. 5 is a schematic view of the extruder configuration of the present invention during liquid discharge;

FIG. 6 is a schematic view of the extruder configuration of the present invention with an exhaust gas treatment unit.

In the figure: 1 extruder, 2 crushers, 3 raw material vibrating screens, 4 bins, 5 screw feeders, 6 fixed bed pyrolysis reactors, 7 inert gas generators, 8 cyclone separators, 9 nitrogen heat exchangers, 10 air preheaters, a waste heat boiler 11, 12 gas-liquid separators, 13 oil-gas condensers, 14 gas-liquid separators, 15 tail gas purification devices, 16 crude oil tanks, 17 combustion-supporting fans, 18 nitrogen circulating fans, 19 high-temperature disc valves, 20 slag cooling tanks and 21 solid slag vibrating screens.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, which are simplified schematic drawings and only schematically illustrate the basic structure of the present invention, and therefore only show the components related to the present invention.

Referring to fig. 1, the device for preparing oil by pyrolyzing polymeric wastes comprises an extruder 1, wherein the bottom of the extruder 1 is communicated with a crusher 2 through a packing auger, 9 chambers are connected in series inside the extruder 1, the temperature of each chamber is adjustable, the plurality of chambers are gradually heated up by adopting resistance heating, the temperature difference between every two adjacent chambers is 10-30 ℃, each chamber is provided with a temperature sensor, and the temperature of each chamber is controlled and displayed through a PLC (programmable logic controller); the high molecular polymerization waste is gradually melted through a plurality of chambers in the temperature rising process, a water tank is arranged at the lower side of the outlet of the extruder, the extruded material falls into the water tank in a molten state and is chilled by water to be cooled to form gray black solid extruded material with certain strength and hardness as a pyrolysis raw material, the crusher 2 is positioned above the raw material vibrating screen 3, the bin 4 is positioned at the right side of the raw material vibrating screen 3 and is communicated with the raw material vibrating screen 3 through a pipeline, the bottom of the bin 4 is communicated with the screw feeder 5, the fixed bed pyrolysis reactor 6 is positioned under a discharge port at the right end of the screw feeder 5, the normal pressure pyrolysis reactor 6 ensures a reaction bed layer of the fixed bed through the synergistic effect of bed materials and hot air, the solid slag S1 containing bed materials is slowly discharged from a slag outlet at the bottom of the normal pressure fixed bed pyrolysis reactor 6 along with the completion of the bed layer pyrolysis reaction, and the fixed bed pyrolysis reactor 6 generates, the device is provided with a cyclone separator 8, fly ash brought out along with oil gas is collected by the cyclone separator 8 and is sent back to the fixed bed pyrolysis reactor 6 by hot air, an inert gas generator 7 is positioned at the right side of the fixed bed pyrolysis reactor 6 and is connected with the fixed bed pyrolysis reactor 6 through a pipeline, the cyclone separator 8 is positioned at the upper right side of the fixed bed pyrolysis reactor 6 and is connected with the fixed bed pyrolysis reactor 6 through a pipeline, a nitrogen heat exchanger 9 and an air preheater 10 are respectively positioned at the upper right side and the upper right side of the cyclone separator 8, the nitrogen heat exchanger 9 and the air preheater 10 are communicated with each other, the nitrogen heat exchanger 9 is communicated with the cyclone separator 8 through a pipeline, the air preheater 10 is respectively communicated with the inert gas generator 7 and the fixed bed pyrolysis reactor 6 through a pipeline, a waste heat boiler is positioned above the fixed bed pyrolysis reactor 6 and is communicated with the nitrogen heat, oil gas condenser 13 is located the top of first gas-liquid separator 12, and pipeline and second gas-liquid separator 14 intercommunication are passed through to oil gas condenser 13's left side below, first gas-liquid separator 12 and second gas-liquid separator below and crude oil tank 16 intercommunication, nitrogen gas heat exchanger 9's right side intercommunication has nitrogen gas circulating fan 18, fixed bed pyrolysis reactor's bottom fixed mounting has high temperature dish valve 19, tail gas cleanup unit 15 and oil gas condenser 13 intercommunication, and cold sediment jar 20 communicates in fixed bed pyrolysis reactor 6's bottom, and cold sediment jar 20's bottom intercommunication has solid sediment shale shaker 21, combustion fan 17's output and air heater 10's right side intercommunication.

The discharge form can be solid granules, block materials or liquid materials according to the structure of a splitter plate at the front end of a cylinder (consisting of a plurality of chambers) of the extruder 1 and the discharge cooling form.

Referring to fig. 3, a lower water tank is arranged below a discharge port of the extruder, the materials are uniformly extruded from a flow distribution plate at the front end of a cylinder of the extruder in an equal and equal pressure manner, the molten material falls into the water tank, and is chilled (water-cooled) by water to form irregular blocky materials which are different in size, have certain strength and hardness and can be used as raw materials of the pyrolysis reactor after being crushed.

Referring to fig. 4, normal temperature air (air cooling) is injected into 2-4 chambers (homogenizing section) before discharging, under the action of the air, water vapor in the molten material in the homogenizing section is blown out by the air, the discharged material of the splitter plate at the front end of the machine barrel is in a loose particle state, and the discharged material can be directly fed into a bin to be uniformly mixed with bed materials.

Referring to fig. 5, low-pressure steam with certain pressure is injected into 2-4 chambers (homogenizing section) before discharging, a pressure sensor is arranged at the head of the extruder, and a splitter plate at the front end of the extruder cylinder is changed into a nozzle structure, so that the material is discharged in a liquid injection state and can be directly injected into a storage bin to be uniformly mixed with bed material.

Considering that the extrusion material of the extruder is used as the raw material for pyrolysis, the forming of the raw material has no strict requirement and can be selected according to the requirements of actual working conditions.

As shown in FIG. 2, the process of the present invention for preparing oil by pyrolyzing polymeric wastes comprises the following steps:

1. feeding the recovered waste plastic a into an extruder 1, wherein the extruder is provided with 9 chambers, heating is started at the temperature of 160-180 ℃ by adopting resistance heating, the temperature difference of each chamber is controlled to be 10 ℃, the field instrument displays that the highest temperature is 210-220 ℃, the rotating speed of a screw is 400 revolutions, extrusion molding is carried out, a small amount of mist is generated in the extrusion process, the gas taste is heavier, and the recycled waste plastic a is discharged after being collected and processed to reach the standard; the extruded material b falls into a water tank and forms a black block under the chilling action of water, the black block has certain strength and porosity, the extruded material is crushed by a crusher 2 and sieved by a raw material vibrating screen 3 to obtain a sieved material c with the diameter of 5mm-10mm, and then the sieved material c is sent into a storage bin 4 and is uniformly mixed with a bed material (alumina balls d1) to obtain a mixed material e, and the weight ratio range of the bed material to the extruded material is 1: 5 to 4: 5;

2. continuously feeding the mixture e into a fixed bed pyrolysis reactor 6 through a screw feeder 5, wherein the reactor adopts electric tracing heat as a heat source, the treatment scale is 2-1000kg/h, nitrogen from a nitrogen steel cylinder is subjected to pressure reduction through a pressure reducing valve and then is heated by an electric heater, hot nitrogen heated to the temperature of 300-;

3. high-temperature oil gas g1 generated by pyrolysis reaction is discharged from the top of the reactor, after fly ash f is removed by a cyclone separator 8, high-temperature pyrolysis gas g2 is discharged and enters a nitrogen heat exchanger 9 to exchange heat with normal-temperature nitrogen n for cooling, the cooled oil gas g3 enters an oil gas condenser 13 to be further condensed to prepare crude oil o, the crude oil o is sent to a crude oil tank 16 for storage, the oil gas condenser 13 condenses the high-temperature oil gas by adopting circulating cooling water, non-condensable gas is sent to a tail gas purification device 15 to be purified by adopting the technologies of dust removal, acid gas removal and denitrification, the purified tail gas is discharged to the atmosphere, and the fly ash f separated by the cyclone separator 8 returns to a fixed bed pyrolysis reactor (6);

4. after the heat exchange with the air in the air preheater 10, part of the nitrogen after temperature reduction is returned to the nitrogen preheater for recycling, and the other part of the nitrogen is sent to the fixed bed pyrolysis reactor 6 as reaction protective gas; the inert gas generator 7 is completely combusted in air k through fuel r or non-condensable gas g7 from a gas-liquid separator to generate oxygen-poor hot air h, and the oxygen-poor hot air is fed into the fixed bed pyrolysis reactor 6 and is fully contacted with the mixture to provide heat for the pyrolysis reaction;

5. the solid slag s1 discharged from the bottom of the fixed bed pyrolysis reactor 6 mainly comprises bed materials and ash slag, is cooled by a cold slag tank 20, is screened by a solid slag vibrating screen 21, then recovers the bed materials d2, returns to a storage bin for recycling, and is sent to a landfill for disposal.

The oxygen-deficient hot air flow at the inlet of the pyrolysis reactor is 2-190m³The temperature is 350-1250 ℃, the pyrolysis temperature in the pyrolysis reactor is controlled to be 350-550 ℃, and the pressure difference value between the inlet and the outlet of the pyrolysis reactor is 20-90 KPa. Pyrolysis gas flow at outlet of pyrolysis reactor is 15-1030m³The flow rate of solid slag at the outlet of the reactor is 0.20-410 kg/h.

The material in the fixed bed pyrolysis reactor 6 is mixed and added by the bed material d1/d2 and the high polymer polymerization waste extrusion screening material c according to the proportion, the problem of adhesion of the extrusion material at a certain temperature is solved, hot air h is blown simultaneously, and the hot air is enabled to realize strong gas-solid mixing with the bed material d1/d2 and the extrusion screening material c, so that the problems of poor heat conductivity and uneven heating during reaction of the high polymer polymerization waste are solved, the coking phenomenon possibly generated when residues are adhered to the wall of the reactor and the bottom of the reactor is avoided, and the continuous safe and stable operation of the equipment is ensured.

A nitrogen heat exchanger 9 and an air preheater 10 are arranged behind the cyclone separator 8, heat exchange is carried out on normal-temperature nitrogen n by utilizing high-temperature pyrolysis gas g1 generated by pyrolysis reaction, the normal-temperature air is further preheated by the nitrogen after heat exchange, and the hot air is sent into the inert gas generator 7 to assist fuel combustion, so that the combustion efficiency is improved, and the fuel consumption is reduced; one part of hot nitrogen is sent into the fixed bed pyrolysis reactor 6 to be used as protective gas, and the hot nitrogen is used as inert gas to be contacted with materials in the reactor, so that the reaction temperature in the reactor is ensured, and the safe operation of the pyrolysis reactor is ensured.

The main components of solid slag S1 at the bottom of the fixed bed pyrolysis reactor 6 are bed material and sludge, the solid slag is collected by a cold slag tank 20, a solid slag vibrating screen 21 is arranged below the cold slag tank 20 to separate the bed material from the sludge, the recovered bed material d2 is uniformly mixed with the extruded material b or the screened material c in the storage bin 4, and then the bed material is lifted by a screw feeder 5 and returned to the fixed bed pyrolysis reactor 6 for recycling, a small amount of fresh bed material d1 is supplemented as required, and the operation cost can be greatly reduced.

The varieties of the processed high molecular polymerization waste raw materials, such as Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), polypropylene (PP), Polystyrene (PS), polyvinyl chloride (PVC)) are not limited, the contents of various varieties components or chlorine are not limited, and the processed raw materials can be pure varieties or the mixture of various high molecular polymerization waste.

Examples

1. Raw materials: waste plastics which are obtained by adopting landfill garbage through multi-stage separation and recovery are mainly waste plastics with a small amount of soil, and are crushed into irregular small blocks by a crusher. The waste plastics are mainly from packaging wastes, automobile wastes and processing wastes, and the percentage of each variety in the waste plastics is respectively Low Density Polyethylene (LDPE), 27%; high Density Polyethylene (HDPE), 21%, polypropylene (PP), 18%; polystyrene (PS), 16%; polyvinyl chloride (PVC), 7%.

2. Analysis of pyrolysis finished products: performing pyrolysis oil preparation by adopting the high polymer waste pyrolysis oil preparation process and the device, respectively collecting crude oil and gas products generated by pyrolysis (gas collection bag sampling), wherein ethyl acetate is adopted to clean a condenser to obtain cleaning liquid, then performing centrifugal rotary evaporation on the cleaning liquid, and finally performing GC-MS analysis on tetrahydrofuran-dissolved rotary evaporation residual liquid to obtain a result, wherein the liquid products comprise organic matters such as C9-C26 alkane, C18-C20 alkene, C12 alkanol, C6-C11 carbene, styrene, benzamide and the like, and are crude oil products; the gaseous product mainly contains CH₄、C₂H₆、C₂H₄、C₃H₈、C₃H₆、C₄H₁₀、C₄H₈、H₂、CO₂And CO.

3) Yield of the product: detection shows that the yield of the synthetic gas is 3-8% and the crude oil rate is 85-90% (wherein the yield of the gasoline-diesel light oil is 50-60% and the yield of the heavy oil is 40-50%) and the residue rate is 7-8% through pyrolysis reaction.

In another embodiment, as shown in fig. 5, the extruder 1 is fed with steam in two to four chambers before discharging, and the extruder outlet is modified into a nozzle, so that the high molecular polymer in the extruder 1 is extruded into liquid state, and directly sprayed into the silo 4 in hot state to be mixed with the bed material as raw material. The extruded liquid raw material and the bed material are fully mixed, so that the subsequent pyrolysis reaction is more sufficient.

As shown in fig. 6, in another embodiment, a gas collecting pipeline is disposed on the upper portion of a plurality of chambers of the extruder 1, and is used for collecting the waste gas generated in the thermal melting process of the high polymer waste, such as HCl generated by melting PVC, and the collected waste gas can be further purified and discharged, the gas collecting pipeline adopts a multi-path gas extraction mode, every other chamber is provided with a gas exhaust port above the middle portion of the chamber, the gas extracted from each gas exhaust port is connected to a main pipe through a pipeline and is sent to a subsequent waste gas treatment unit, and the waste gas treatment unit adopts a small SCR denitration and alkaline washing deacidification device to treat the collected extrusion waste gas, so that the extrusion waste gas is purified and discharged to the.

In conclusion, the process for preparing oil by pyrolyzing polymeric wastes adopts a double-feeding mode, raw materials can be solid granular materials or liquid materials, the feeding form is flexible and convenient, a multi-section heating mode is adopted, direct external heating is adopted, the upper section, the middle section and the lower section of a fixed bed pyrolysis reactor 6 are respectively subjected to multi-section heating, the pyrolysis temperature in the reactor is ensured, the problems of poor thermal conductivity of the polymeric wastes and uneven heating in reaction are solved, the heat transfer efficiency and the utilization rate of heat energy are improved, heat sources are selected more, hot air, hot nitrogen, steam and the like can be adopted, meanwhile, a bed material system is arranged, fresh bed materials and solid granular materials or liquid and semi-liquid materials are mixed in a raw material bin 4, the bed materials after reaction are cooled by a cold slag tank 20, solid slag vibrating screens 21 are separated and recovered, the bed materials are returned to the raw material bin 4 for recycling, and the bed materials are adopted to participate in the, the method improves the reaction mass and heat transfer efficiency, reduces feeding blockage, shortens the reaction time, solves the problems of poor thermal conductivity of the high polymer polymerization waste and uneven heating in the reaction, avoids the coking phenomenon possibly generated by the adhesion of residues on the wall and the bottom of the reactor, and ensures the continuous, safe and stable operation of the equipment. The extruder 1 has the function of removing chlorine and acid gas, adopts an electric heating or steam heating mode to extrude polymer wastes in various forms into solid or liquid extruded materials, so that most of chlorine and acid gas are removed from PVC and PETE materials in the extrusion stage, and the problem of strong corrosivity caused by chlorine and acid gas possibly generated by pyrolysis in a reaction system is solved. According to the invention, hot air and hot nitrogen are directly contacted with the mixed raw material, on one hand, inert gas is used as reaction protective gas, on the other hand, heat is provided for pyrolysis reaction, and the reaction safety and stability are ensured while the reaction heat transfer efficiency is improved. In addition, the invention also considers the integrated use of heat, and oxygen-poor hot air and hot nitrogen generated by the inert gas generator 7 are sent to the atmospheric fixed bed reactor to ensure the heat energy required by the pyrolysis reaction. In a word, the invention has the advantages of wide raw material application range, simple device structure, low equipment manufacturing cost, stable performance and low operation cost, achieves the effect of strong overall practicability, and solves the problem that the prior treatment technology for the high polymer waste at home and abroad has more defects.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. a method for producing oil by pyrolysis of macromolecular polymer waste, is characterized in that, comprises the steps: S1. The polymer waste is extruded by the extruder (1) and the extruded material is sent to the silo (4) to be uniformly mixed with the bed material to obtain a mixture; S2, the mixture is sent into the fixed-bed pyrolysis reactor (6), and a pyrolysis reaction is carried out; S3. After the high-temperature oil and gas generated by the pyrolysis reaction is removed from the fly ash by the cyclone separator (8), it enters the nitrogen heat exchanger (9), and exchanges heat with the nitrogen gas from the air preheater (10). After the oil and gas enters the waste heat boiler (11) to recover heat energy, it enters the first gas-liquid separator (12) for gas-liquid separation, the liquid is sent to the crude oil tank (16) for storage, and the gas enters the oil and gas condenser (13) and the second gas-liquid The separator (14) is further condensed to obtain crude oil, which is sent to the crude oil tank (16) for storage, and the non-condensable gas is sent to the inert gas generator (7) as an auxiliary fuel, or sent to the exhaust gas purification device (15) for treatment and then discharged up to the standard ; S4. A part of the nitrogen after the heat exchange is sent to the fixed bed pyrolysis reactor (6) as reaction protection gas, and a part is sent to the air preheater (10) to exchange heat with the air, and after the heat exchange, the nitrogen circulation fan (18) The preheated air from the air preheater (10) is sent to the inert gas generator (7) to assist the combustion of the fuel, and the fuel may come from gas-liquid The non-condensable gas of the separator (14) is combusted in the inert gas generator (7) to generate oxygen-depleted hot air, and the oxygen-depleted hot air is sent into the fixed-bed pyrolysis reactor (6), and fully contacts with the mixture for The pyrolysis reaction provides heat; S5. The solid slag discharged from the bottom of the fixed bed pyrolysis reactor (6) mainly contains bed material and ash. (4) Reuse, and send ash and slag to landfill for disposal. 2. method according to claim 1, is characterized in that, under extruder (1) discharge port is provided with lower water trough, molten state material falls into the water trough after extrusion, under the chilling action of water, Irregular lumps are formed, which are crushed and screened and sent to the silo (4). 3. method according to claim 1, it is characterized in that, in extruder (1) homogenization section is sprayed into normal temperature air, the water vapor in molten material is blown out by wind, extruded material is in loose particle state, is directly sent into Silo (4). 4. The method according to claim 1, characterized in that, low-pressure steam is injected into the homogenization section of the extruder (1), the front end of the extruder barrel is set as a nozzle structure, and the extruded material is ejected in a liquid state. The material is directly sprayed into the silo (4) to be mixed with the bed material. 5. The method according to claim 1, wherein the bed material is selected from at least one of alumina balls, ceramic balls, molecular sieves or fine sand. 6 . The method according to claim 1 , wherein the weight ratio of the bed material and the extruded material ranges from 1:5 to 4:5. 7 . 7. method according to claim 1, is characterized in that, the pyrolysis reaction temperature of step S2 is 400-700 ℃, in step S4, oxygen-depleted hot air is sent into the air inlet air velocity setting of described fixed bed pyrolysis reactor At 0.2-0.5m/s, the oxygen content concentration of the oxygen-depleted hot air is <30ppm. 8. A device for producing oil by pyrolysis of polymer polymer waste, characterized in that it comprises an extruder (1), the bottom of the extruder (1) is communicated with a crusher (2) through an auger, and the crusher (2) is connected to the bottom of the extruder (1). The machine (2) is located above the raw material vibrating screen (3), the silo (4) is located on the right side of the raw material vibrating screen (3) and is communicated with the raw material vibrating screen (3) through a pipeline, and the bottom of the silo (4) is connected with a The screw feeder (5), the fixed bed pyrolysis reactor (6) is located just below the discharge port at the right end of the screw feeder (5), and the inert gas generator (7) is located in the fixed bed pyrolysis reactor (6) The right side and the two are connected by pipelines, the cyclone separator (8) is located at the upper right of the fixed bed pyrolysis reactor (6) and the two are connected by pipelines, the nitrogen heat exchanger (9) and the air preheater (10) ) are respectively located above and to the right of the cyclone separator (8), the nitrogen heat exchanger (9) and the air preheater (10) are communicated with each other, and the nitrogen heat exchanger (9) is communicated with the cyclone separator (8) through a pipeline , the air preheater (10) is communicated with the inert gas generator (7) and the fixed bed pyrolysis reactor (6) respectively through pipes, and the waste heat boiler (11) and the first gas-liquid separator (12) are respectively located in the nitrogen exchange Above and to the right of the heat exchanger (9), the waste heat boiler (11) is communicated with the nitrogen heat exchanger (9) and the first gas-liquid separator (12) through pipes, and the first gas-liquid separator (12) is connected with the first gas-liquid separator (12) through pipes. The crude oil tank (16) is communicated, the oil and gas condenser (13) is located above the first gas-liquid separator (12) and communicated with the first gas-liquid separator (12) through a pipeline, and the lower left of the oil and gas condenser (13) It is communicated with the second gas-liquid separator (14) through a pipeline, the exhaust gas purification device (15) is communicated with the second gas-liquid separator (14), the first gas-liquid separator (12) and the second gas-liquid separator (14) ) is communicated with the crude oil tank (16) below, the cold slag tank (20) is communicated with the bottom of the fixed bed pyrolysis reactor (6), and the bottom of the cold slag tank (20) is communicated with a solid slag vibrating screen (21), The output end of the combustion-supporting fan (17) is communicated with the right side of the air preheater (10), the output end of the nitrogen circulating fan (18) is communicated with the right side of the nitrogen heat exchanger (9), and the high temperature disc valve (19) is fixedly installed at the bottom of the fixed bed pyrolysis reactor (6). 9 . The device for producing oil by pyrolysis of polymer polymer waste according to claim 8 , wherein the extruder ( 1 ) has three to ten chambers inside, and the outlet of the extruder ( 1 ) is a shunt. 10 . plate or nozzle. 10 . The device for producing oil by pyrolysis of polymer polymer waste according to claim 9 , wherein a gas collecting pipeline is arranged on the upper part of the multiple chambers of the extruder, and the gas collecting pipeline adopts multi-channel air extraction. 11 . In this way, every other chamber is provided with an exhaust port above the middle of the chamber, and each exhaust port is connected by a pipeline to a main pipe, and sent to the subsequent exhaust gas treatment unit, which adopts a small SCR denitration and alkali treatment unit. The acid elution unit treats the collected extrusion waste gas.

Images