JP4154929B2 - Method for producing useful substances from plastic - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a useful substance such as coke using plastic as a raw material, and particularly relates to a method for producing a useful substance that can effectively use waste plastic.
[0002]
[Prior art]
About 10 million tons of waste plastic is generated annually. The disposal method is 37% for landfill and 24% for simple incineration, and it is effectively reused for blast furnace reductant, coke raw material, gasification, etc. The ratio is 39%, which is very low compared to the recycling rate of other materials, such as 70% for steel cans and 60% for aluminum cans. Increasing the recycling rate of waste plastics is an extremely important issue as the demand for the formation of a recycling society increases. Plastic raw materials are valuable fossil fuel oils that depend on foreign countries. Not only environmental problems associated with waste treatment, but also from the standpoint of effective use of resources, such as so-called chemical recycling and material recycling. It is most desirable to reuse it. As chemical recycling utilizing the chemical properties of plastics, for example, Japanese Patent Laid-Open No. 7-138576 discloses an oiling technique by hydrocracking waste plastics.
[0003]
On the other hand, methods for producing coke (oil coke) using petroleum heavy oil or coal tar as a raw material are known. US Pat. No. 4,624,775, US Pat. No. 3,759,822, JP-A-52-28501, It is described in Japanese Patent Publication No. 52-112003. Oil coke is a solid residue produced as a by-product when pyrolyzing heavy residual oil in order to increase the yield of gasoline, light oil and the like in the petroleum refining process, and is used as an inexpensive fuel. Higher quality oil coke is called needle coke and is used as an aggregate raw material for graphite furnace materials of nuclear reactors. As a waste disposal method for polymer materials such as plastics related to these, a technique for producing coke by mixing plastic with raw material oil using an existing coker facility is disclosed in JP-A-6-80970. ing.
[0004]
[Problems to be solved by the invention]
However, according to the technology for hydrolyzing waste plastic by hydrocracking described in JP-A-7-138576, unreacted residues are generated when hydrocracking is performed at a low temperature, and coking is generated in the reactor at a high temperature. There are many problems to be solved.
[0005]
Further, in the method of producing coke using petroleum heavy oil or coal tar as a raw material, there is a problem that the quality of the coke is not stable because the properties of the raw material oil are not stable, and the quality of the coke is lowered. When petroleum-based feedstock is used, the content of sulfur and metals in the feedstock varies. Even when a coal tar-based raw material is used, for example, the content of an aromatic hydrocarbon or a heterocyclic compound containing an alkyl side chain in the coal tar varies due to a change in the operating rate of a coke oven that simultaneously produces coal tar.
[0006]
Furthermore, if the technology proposed in Japanese Patent Application Laid-Open No. 6-80970 is used, coke can be produced using waste plastic as a part of raw material in order to treat waste plastic, but it is waste. There is a problem that stable quality coke cannot be produced because the compositional variation of the waste plastic affects the properties and yield of the coke produced.
[0007]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a method for producing a useful substance using plastic as a raw material, which can produce stable and high-quality coke.
[0008]
Another object of the present invention is to enable effective use of waste plastics.
[0009]
[Means for Solving the Problems]
The features of the present invention for solving such problems are as follows.
[0010]
(1) A useful substance made of plastic as a raw material, comprising the steps of mixing heavy oil and plastic, heating and melting the mixture, and hydrocracking the heat-melted mixture. Production method.
[0011]
(2) The method according to (1), comprising: a step of separating a gas component from a product obtained by hydrocracking; and a step of coking the product from which the gas component has been separated to obtain coke. A method for producing a useful substance using the described plastic as a raw material.
[0012]
(3) A step of separating a gas component from a product obtained by hydrocracking, a step of separating a product oil having a boiling point of 280 ° C. or higher from the product obtained by separating the gas component, and caulking the product oil And a method for producing a useful substance using the plastic according to (1) as a raw material.
[0013]
(4) a step of separating a gas component from a product obtained by hydrocracking, and a step of separating a light component having a boiling point of less than 280 ° C. from the product obtained by separating the gas component. A method for producing a useful substance using the plastic according to any one of (1) to (3), wherein light oil is produced from the components.
[0014]
(5) The product according to any one of (1) to (4), wherein two or more kinds selected from coke, light oil, and organic gas are simultaneously produced from a product obtained by hydrocracking. Of a useful substance made from plastics.
[0015]
(6) A method for producing a useful substance using the plastic according to any one of (1) to (5), wherein waste plastic is used as the plastic.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a useful substance using plastic as a raw material, comprising the steps of mixing heavy oil and plastic, heating and melting the mixture, and hydrocracking the heat-melted mixture. Using this production method, useful substances such as coke, light oil and organic gas are produced.
[0017]
The plastic used in the present invention is a polymer material containing hydrocarbon as a main component, and any shape can be used. In the present invention, it is preferable to use waste plastic as the plastic from the viewpoint of recycling the waste plastic and also for producing coke at low cost. The waste plastic is not particularly limited. For example, it is a plastic waste used for packaging foods and various products at home, and the main component is a thermoplastic resin that has a high hydrogen concentration and is easily pyrolyzed. What is to be done is suitable. Particularly suitable are thermoplastic resins that do not contain chlorine, such as polyethylene, polypropylene, and polystyrene. Resins containing chlorine, such as vinyl chloride resin, can be removed in advance from waste plastics by a method such as centrifugation or specific gravity separation. When using chlorine-containing resins, hydrogen chloride is generated when heated and mixed with heavy oil, so a device for separating and recovering the generated hydrogen chloride may be installed. The waste plastic may contain unsuitable materials such as glass and metal that do not melt in heavy oil during hydrocracking, but after pulverizing the waste plastic into a pulverized product, It is preferable to heat and mix to the extent that the unsuitable matter mixed into the waste plastic is precipitated in heavy oil, and after separating and collecting the unsuitable matter from the heavy oil, the mixture of heavy oil and plastic is preferably heated and melted. In addition, it is preferable to pulverize the plastic and mix it with heavy oil because of the effect of shortening the hydrocracking time. The crushing diameter at the time of crushing the plastic may be appropriately set so as to be easily handled according to the type of plastic. However, the larger the crushing diameter, the longer the hydrocracking and the lower the removal rate of unsuitables.
[0018]
The heavy oil used as a raw material for the useful substance in the present invention is preferably present as a liquid at the hydrocracking temperature of the plastic, and the decomposed plastic is dissolved or uniformly dispersed as a solvent for the decomposed plastic. Specific examples include atmospheric distillation petroleum residual oil, ethylene tar, coal tar pitch, coal liquefied oil residue, etc., or a mixture of any two or more thereof, light oil content adjusted, polymerized And those to which a gelling agent or the like is added.
[0019]
In the step of mixing the above heavy oil and the above plastic and heating and melting the mixture, the mixing ratio when mixing the heavy oil and the plastic is, as a mass ratio, heavy oil: plastic = 10: 1 to 1:10. It is preferable to do. If the proportion of plastic is high, it is possible to process a large amount of waste plastic and produce inexpensive coke, but its viscosity at the time of melting increases, making it difficult to transport, and coking occurs during hydrocracking. Problems occur. Heavy oil and plastic are mixed and then heated, and the plastic is dissolved or dispersed in heavy oil and melted.
[0020]
Hydrocracking a mixture of heavy oil and plastic melted by heating. Hydrocracking is carried out in order to thermally decompose heavy oil and plastic to lower the molecular weight, but is generally carried out using a pressure vessel because it is performed at a temperature of 300 ° C. or higher and under pressure. The hydrocracking temperature and pressure in the hydrocracking step are set so that the hydrocracking of the plastic is sufficiently advanced. Although this differs depending on the type and amount of plastic used, a pressure of about 10 to 200 atm, preferably about 20 to 70 atm is appropriate at a temperature of about 300 to 500 ° C, preferably 350 to 450 ° C. For this hydrocracking, an iron catalyst, a petroleum desulfurization catalyst, or the like can be used. In addition, since hydrogen is present in the plastic component, hydrogen addition is not necessarily required for hydrocracking, but hydrogen can be used to promote the reaction. When hydrogen is used, a hydrogen-containing gas may be appropriately blown from the lower part of the vessel used for the hydrogenation reaction, but it is desirable to use an inexpensive coke oven gas or the like. When hydrogen is added in the hydrocracking step, the supply amount of hydrogen is about 0.05 to 5.0 mass%, preferably about 0.1 to 1.0 mass% with respect to the total amount of plastic and heavy oil. It is. The hydrocracking behavior differs depending on the type of plastic, but when hydrogen gas is supplied, the carbon bond is broken by thermal cracking, the molecular weight is lowered, and hydrogen from the hydrogen donor generated by the reaction between hydrogen gas and heavy oil is generated. It is considered that diesel oil is produced. When hydrogen gas is not used, hydrogen donors are generated in heavy oil. Therefore, it is considered that hydrogen gas generated by thermal decomposition of plastic reacts with heavy oil to cause hydrogenation reaction of heavy oil.
[0021]
Useful substances such as coke, light oil and organic gas can be produced from the product obtained by the above hydrocracking.
[0022]
In order to produce coke, a production method comprising a step of separating a gas component from a product obtained by the above hydrocracking, and a step of coking the product from which the gas component has been separated to obtain coke. Use. Alternatively, a step of separating a gas component from a product obtained by the above hydrocracking, a step of separating a product oil having a boiling point of 280 ° C. or higher from the product obtained by separating the gas component, and the product oil A production method having a step of coking to obtain coke is used. Each step will be described below.
[0023]
In order to separate the gas component from the product obtained by the above hydrocracking, it is preferable to separate the gas by returning the product to normal pressure using a separator or the like. The gas separated in this step can be used as an organic gas. The organic gas is mainly composed of hydrogen, and additionally contains methane, ethane and the like.
[0024]
The product after gas separation is coked to produce coke. Although the product can be coked as it is, the product after gas separation is obtained by distilling the distillate having a boiling point of 280 ° C. or higher (hereinafter referred to as product oil) and the distillate having a temperature of less than 280 ° C. The product oil is preferably caulked separately (hereinafter referred to as light components). The light component is difficult to coking and only exists as a liquid or gas in the coking process, so it is a loss of the heat source for heating in the coking oven, and coking is performed by separating and removing the light component from the product. The reaction efficiency in the process of obtaining is improved.
[0025]
The product after gas separation or the product oil obtained by separating the product after gas separation into a product oil and a light component (hereinafter referred to as product oil) is coking (heated material) Coke is produced by the method of leaving oil). In addition, when the foreign material mixed with production | generation oil etc. becomes a problem, it can be taken out by solid-liquid separation operations, such as filtration and centrifugation, by making a foreign material settle and isolate | separating with production | generation oil. The coking method is not particularly limited, and conventionally used delayed coking method, fluid coking method, contact coking method and the like can be applied as they are. The most industrialized delayed coking method introduces coke oven-heated feedstock oil into a coke drum equipped with two units, holds it for a certain period of time, and coke it into cracked oil (oil generated by coking. Is a method of producing coke together with a mixture. Fluid coking is a method in which fine coke is fluidized and used as a heat medium, and raw oil is coked on the surface of the coke. The contact method is the same fluidized bed method as the fluid coker, but is a method that allows easy recovery of volatiles.
[0026]
Even if some quinoline insoluble (QI) is contained in the product oil etc., normal coke can be produced. However, when producing needle coke, QI is about 0.5 mass%. It is desirable to remove it into coke. As a method for removing QI, a known technique can be adopted, and it is also possible to remove the produced oil by filtration, centrifugation, etc. For example, as disclosed in JP-B-57-30159, An effective method is to add a mixed solvent of an aromatic solvent and an aromatic solvent, precipitate QI together with a component insoluble in the mixed solvent, and separate and remove it. A known technique may be used when needle coke is produced using the product oil from which QI has been removed. For example, coal tar pitch is used as heavy oil, and low temperature carbonization is performed at 450 to 500 ° C. under pressure in a delayed coker to produce raw coke. It can be calcined into needle coke. The obtained needle coke can be further mixed with a binder pitch and molded, and then graphitized at a temperature of 2500 ° C. or higher to obtain a desired graphite electrode.
[0027]
When heavy oil hydrocracked with plastic as described above is used as a raw material for coke, the properties (oxygen, sulfur amount, molecular weight, hydrogen amount, etc.) of the raw material oil become constant, so the properties are stable and easy to coking. Since the amount of the component increases, the yield (yield) increases, and the yield is highly stabilized. Therefore, even if the properties of the feedstock fluctuate, it is possible to reduce fluctuations in the coke properties and yield that are produced. Moreover, compared with the case where the heavy oil which has not been hydrocracked is used, the fluidity | liquidity at the time of coking improves, and it is possible to manufacture the quality coke which has a flow structure. In addition, oxygen, sulfur, and nitrogen in the raw material can be removed as water, hydrogen sulfide, and ammonia, respectively, by hydrocracking, reducing the oxygen, sulfur, and nitrogen content, and coke with good crystallinity. Can be manufactured.
[0028]
Light oil is produced from the above light components. Using a production method comprising a step of separating a gas component from a product obtained by hydrocracking, and a step of separating a light component having a boiling point of less than 280 ° C. from the product obtained by separating the gas component, Light oil is produced from light components. Since the light component has a boiling point of less than 280 ° C., it can be used as a fuel or other chemical raw material as light oil as it is or by distillation separation.
[0029]
As described above, coke, light oil and organic gas can be produced from the product obtained by hydrocracking, but it is also possible to produce two or more of these useful substances simultaneously, which is efficient. is there.
[0030]
In addition, when waste plastic is used as the plastic, coke, light oil, and organic gas can be produced at low cost, and reuse of the waste plastic can be promoted, which is very preferable.
[0031]
An embodiment of a production method for simultaneously producing coke, light oil and organic gas using waste plastic as a raw material will be described below with reference to the drawings. FIG. 1 shows a flow for producing coke, light oil, and organic gas, which are useful substances, using the method of the present invention. The raw material plastic A, heavy oil B, and catalyst C as required are mixed in a mixing tank 1. The mixture is dissolved by heating and sent to the reaction tower 2. Hydrogen D is blown from the bottom of the reaction tower 2 and hydrocracking is performed at a predetermined temperature and pressure. The mixture of plastic and heavy oil hydrocracked in the reaction tower 2 is sent to the separation tank 3, and after separating the gas E in the separation tank 3, the mixture is sent to the distillation tower 4. In the distillation column 4, the light component F is distilled off to separate the produced oil and the light component F. The product oil is for coke production, and the light component F is light oil. The gas separated in the separation tank 3 and the gas generated in the distillation column 4 (the generated gas in the distillation column 4 is generated in the following coking) are recovered as the organic gas E. The obtained oil is freed from the QI component by the centrifugal separator 5. For example, when using the delayed coking method, the oil is transferred to the coking furnace 6 and heated to about 450 to 500 ° C. in the coking furnace 6, and then the coke drum. In step 7a, coking is performed for about 8 hours to produce coke. By installing multiple coke drums and using them sequentially, coke production can be made a continuous operation. For example, coke drums 7a and 7b are used to perform coking with coke drum 7a, while coke drum 7b performs decoking, and coke is cut out to prepare for the next coking. To produce coke continuously. The cracked oil and organic gas produced simultaneously with coke at the time of coking can be sent to the distillation column 4 and reused as raw materials for coke and the like. When the organic gas generated simultaneously with the coke is not sent to the distillation column 4, the organic gas E is recovered only from the separation tank 3.
[0032]
【Example】
Coke, light oil and organic gas were produced according to the production flow shown in FIG. In this treatment method, the waste plastic A and heavy oil B were put into the mixing tank 1 and dissolved by heating, sent into the reaction tower 2, and hydrogen was blown into the bottom of the reaction tower 2. The mixture of waste plastic and heavy oil that had been hydrocracked in the reaction tower 2 was sent to the separation tank 3 where the gas E was separated and then sent to the distillation tower 4. In the distillation column 4, the light component F was distilled off to obtain a product oil for oil coke. The obtained product oil was removed from the QI component by the centrifugal separator 5 and transferred to the coking furnace 6. After heating to about 450 to 500 ° C., coking was performed for about 8 hours with the coke drums 7a and 7b to produce oil coke. The coke drums 7a and 7b were alternately decoked to cut out the coke.
[0033]
As the waste plastic A, a container packaging plastic containing about 40 mass% of polyethylene, about 40 mass% of polypropylene, and about 20 mass% of polystyrene was supplied to the mixing tank 1 at a flow rate of 10 kg / h. As heavy oil B, coal tar vacuum heavy oil having a normal pressure conversion of 350 ° C. to 550 ° C. was supplied to the mixing tank 1 at a flow rate of 20 kg / h. In the mixing tank 1, waste plastic A was dissolved in heavy oil B at 200 ° C. As a catalyst, natural pyrite ground to 0.5 μm was used and supplied at 0.2 kg / h. Hydrogen D was supplied from the lower part of the reaction tower 2 at a flow rate of 2.5 Nm ³ / h. The reaction temperature in the reaction tower 2 was 400 ° C., the pressure was 50 atm, and the reaction time was 1 hour. The mixture of waste plastic and heavy oil that was hydrocracked in the reaction tower was sent to the separation tank 3 at a flow rate of 30.3 kg / h. The separation tank 3 is an apparatus for returning the mixture from pressure to normal pressure and separating the gas. The exhaust gas E separated from the separation tank 3 is mainly composed of hydrogen and has a flow rate of about ³ Nm ³ / h. It was discharged. The mixture of waste plastic and heavy oil from which the gas was separated in the separation tank 3 was sent to the distillation tower 4 at a flow rate of 29.8 kg / h. In the distillation tower 4, light oil having a boiling point of less than 280 ° C. was discharged at 11.5 kg / h, and a coking oil having a boiling point of 280 ° C. or higher was discharged at 18.3 kg / h, and the produced oil was transferred to the centrifugal separator 5. In the centrifuge 5, the QI component was removed under the conditions of temperature, 250 ° C., and rotation speed of 2000 rpm. The coke product oil from which the QI component amount was removed to 0.5 mass% or less was transferred to the coking furnace 6. In the coking oven 6, the product oil for coke was heated to 500 ° C. The heated product oil for coke was transferred to the coking drum 7a. In the coking drum 7a, after feeding, coking was performed at 4 atm, a temperature of 450 ° C., and a holding time of 8 hours, and the deposited coke was cut out. Coke was obtained at a yield of 7.9 kg / h, cracked oil and organic gas at 10.4 kg / h. The produced cracked oil and organic gas were returned to the distillation column 4, and the gas and light oil were separated and reused as the produced oil for coke. By repeating the same operation alternately on the coking drum 7a and the coking drum 7b, coke could be continuously produced.
[0034]
As a result of continuous operation, the yields of organic gas, light oil, and coke obtained in this process were 25, 49, and 26 mass%, respectively. The organic gas contained 40% hydrogen, 30% methane, and 20% other gases. The light oil, which is the light component F, contained 30% of benzene, toluene and xylene and about 70% of aliphatic hydrocarbons such as hexane and decane. The coke produced had a flow structure, was of good quality compared to coke produced using only heavy oil, could be used as needle coke, and the yield increased by 5%.
[0035]
【The invention's effect】
As described above, according to the present invention, even if the properties of the raw material oil fluctuate, it is possible to reduce fluctuations in the properties and yield of coke to be produced, and it is possible to produce stable and high-quality coke. In addition, coke can be provided at low cost, and at the same time, organic gas such as hydrogen and methane, and light oil such as benzene, toluene, and xylene can be manufactured at low cost.
[0036]
Furthermore, recycling of waste plastic can be promoted because it can be effectively recycled by material recycling.
[Brief description of the drawings]
FIG. 1 is a flow sheet for producing coke, light oil, and organic gas using the method of the present invention.
[Explanation of symbols]
1 ... mixing tank,
2 ... reaction tower,
3 ... separation tank,
4 ... Distillation tower,
5 ... centrifuge,
6 ... caulking furnace,
7a ... Caulking drum,
7b ... Caulking drum,
A ... Plastic,
B ... Heavy oil,
C ... Catalyst,
D ... Hydrogen,
E ... Organic gas,
F ... Light

Claims (2)

Mixing a heavy oil and a plastic, heating and melting the mixture, hydrocracking the heated and melted mixture, and separating a gas component from the product obtained by the hydrocracking; And a step of coking the product from which the gas component has been separated to obtain coke, and a method for producing a useful substance using plastic as a raw material. Mixing a heavy oil and a plastic, heating and melting the mixture, hydrocracking the heated and melted mixture, and separating a gas component from the product obtained by the hydrocracking; The method comprises separating a product oil having a boiling point of 280 ° C. or higher from the product from which the gas component has been separated, and a step of coking the product oil to obtain coke. A method for producing useful substances.

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