CN1200075C - Method for making fuel oil by mixing-cracking waste plastics, waste oil and heavy oil - Google Patents

Abstract

The present invention relates to a method for preparing fuel oil by mixing and cracking waste plastic, waste oil and heavy oil. The method comprises the steps that after the heavy oil and the waste oil are mixed according to the proportion of 0.5 to 1.5: 0.5 to 1.5, the mixture is used as oil raw materials; after plastic raw materials and the oil raw materials are mixed according to the proportion of 1 to 3: 1 to 3, the mixture is continuously added into a cracking reactor, a stirrer is started (the rotation speed is from 10 to 30 circles/min), the mixture starts to be heated, the temperature rise speed is controlled from 150 to 250 DEG C /h, the cracking temperature is from 370 to 450 DEG C, reaction cracked gas is collected and is modified by catalysts, the modified cracked gas is processed by a condenser to obtain liquid oil products and gas products, the liquid oil products are fractionated to obtain gasoline, diesel oil and heavy oil, the heavy oil returns to the reactor and is used as reaction raw materials, and the gas products are collected and stored. The present invention not only solves the utilization problem of the waste plastic, the heavy oil and the waste oil, but also solves the problems of large slag quantity and coke formation caused by the poor heat transfer property of the waste plastic in a cracking process of the waste plastic. The present invention has the advantages of oil yield increase of the gasoline and the diesel oil, quality improvement of the gasoline and the diesel oil, high productive efficiency and obvious economic benefit increase.

Description

Method for producing fuel oil by mixed pyrolysis of waste plastics, waste oil and heavy oil

Technical Field: The present invention relates to a method for recycling resources from waste, in particular to a method for producing fuel oil by mixing and cracking waste plastics, waste oil and heavy oil produced in the petroleum production process.

Background technology: waste plastics and waste oil are common pollutants in daily life, and after proper treatment, they can be turned into valuable resources.

For waste plastics, the traditional treatment and disposal methods include landfill, incineration, recycling, recycling, and replacing existing plastics with degradable plastics. Among them, using waste plastics to produce liquid fuel is a better treatment method, which is more suitable for my country's national conditions, and can not only deal with white pollution, but also obtain resources.

However, the direct cracking of waste plastics to produce fuel oil has the problems of excessive slag and coking. There are three problems in the cracking reaction of waste plastics. The thermal conductivity of plastics is poor, and the viscosity of molten materials is high, which is easy to stick to the wall and produce carbon deposits, which is not easy to solve.

The treatment of waste oil is usually used as fuel, regeneration, and reuse. In my country, waste oil is generally prepared by sulfuric acid-clay method to produce base oil. This method produces a large amount of acid residue at the same time, which is easy to cause secondary pollution.

Heavy oil is generally produced by catalytic cracking method to produce light oil and chemical raw materials with higher economic value, and some small factories burn it directly as fuel.

At present, there are some technologies at home and abroad that use the mixed cracking of waste plastics and heavy oil. Generally, the inorganic heat carrier is heated in the combustion chamber to a high temperature, and then sent into the trough-shaped screw reactor by a screw conveyor. Waste plastics are squeezed into and sealed trough-shaped spiral reactor, and heavy oil is pumped into the reactor at the same time, so that the raw material is directly mixed with the heat carrier for heat transfer and cracking reaction, and decomposes to generate gas phase hydrocarbons and residues. Gas-phase hydrocarbons are catalyzed by the fixed bed to generate small-molecule gas-phase hydrocarbons, and enter the fractionation tower for fractionation. The mixture formed by the inorganic heat carrier and the cracking residue is driven by the screw and flows into the gasification chamber, and enters the separation box through the screw conveyor. The high-temperature flue gas is sent into the separation box by a blower, and the mixture is continuously blown into the cyclone separator to collect the solid mixture and separate the gas. The above-mentioned solid mixture is sent into the combustion chamber by a screw conveyor for combustion. In the combustion chamber, the organic matter in the mixture is burned, and the inorganic heat carrier is heated to a high temperature, and falls into the tank-shaped reactor to provide heat for the cracking reaction. It is characterized in that the raw material is directly mixed with the heat carrier to undergo heat transfer and cracking reaction, and the heat carrier is always in a continuous cycle state of heating-exothermic-heating. Although this method solves the shortcomings of poor heat and mass transfer effect when waste plastics are pyrolyzed alone to a certain extent, it still has the problems of large amount of slag and easy coking.

Summary of the invention: The technical problem to be solved by the present invention is to provide a method of mixing and cracking waste plastics with waste oil and heavy oil, aiming at the problems of poor thermal conductivity and poor fluidity in the pyrolysis process of waste plastics, which easily produce a large amount of residue and coking. Improve the heat transfer and mass transfer conditions of the process, so as to effectively solve the problems of large amount of slag and coking, improve production efficiency and product quality, and improve economic benefits.

The technical scheme of the present invention is as follows: a method for producing fuel oil by mixing and cracking waste plastics, waste oil and heavy oil, which is characterized in that heavy oil and waste oil are mixed in a ratio of 0.5-1.5:0.5-1.5 as oil raw materials, Mix plastic raw materials and oil raw materials in a ratio of 1-3:1-3, then continuously add them to the pyrolysis reactor, start the agitator (rotation speed is 10-30 rpm), and start heating, and control the heating rate at 150-250 ℃/h, and control the cracking temperature to 370-450°C, collect the reaction cracked gas and upgrade it with a catalyst, the cracked gas after upgrading is passed through the condenser to obtain liquid oil and gas products, and the liquid oil is then fractionated to obtain gasoline, Diesel oil, heavy oil, and heavy oil are returned to the reactor as reaction raw materials, and gas products are collected and stored.

The plastic raw material can be mixed waste plastics, which is formed by mixing polyethylene (PE), polypropylene (PP) and polystyrene (PS) in a ratio of 0.5-1.5:0.5-1.5:0.5-1.5.

The waste oil is an oily liquid substance obtained by mixing waste gasoline, waste diesel oil, and waste base oil in any proportion. The heavy oil mainly refers to long-chain, large-molecular-weight, and high-viscosity oil products produced during petroleum production.

The catalyst is any one of HY, Ni-REY, HZSM-5, HC-1 molecular sieve catalyst, or modified catalyst, SiO ₂ /Al ₂ O ₃ .

When the waste plastics are cracked separately, it is difficult to flow because the waste plastics are solid. After the waste plastic is melted, due to the nature of the waste plastic, it is difficult to transfer heat and mass effectively. However, when waste plastics, waste oil and heavy oil are mixed and pyrolyzed, since waste oil and heavy oil are liquid and have excellent heat transfer performance, waste oil and heavy oil are both reactants and heat transfer substances. Thus, the heat transfer efficiency of the whole system can be greatly improved. Moreover, after the waste oil and heavy oil are added, under the action of effective stirring, the molten agglomeration formed by waste plastics can be diluted, dispersed, and flow together, thereby effectively improving the mass transfer efficiency of the system.

Therefore, compared with the prior art, the present invention has the following advantages: it not only solves the problem of utilization of waste plastics, heavy oil, and waste oil, but also handles these environmental pollutants, and also solves the heat transfer problem caused by waste plastics in the process of cracking waste plastics. It also improves the yield of gasoline and diesel produced by waste plastic pyrolysis, improves the quality of gasoline and diesel, and improves production efficiency and economic benefits.

Description of drawings:

Fig. 1 is the process flow chart of the embodiment of the present invention, among the figure 1 is screw conveyor; 2 is waste oil and heavy oil preheating still; 3 is pyrolysis reactor; 4 is cyclone separator; 5,8 is cooler; 6 7 is a rectification tower; 9 is a compressor.

Fig. 2 is a schematic diagram of the cracking reactor structure and the connection relationship with the screw conveyor, in which 31 is a fixed bed reactor; 32 is a stirrer; 33 is a continuous slag remover; 1 is a screw conveyor;

Detailed ways:

Example 1:

Mix polyethylene, polypropylene, and polystyrene at a ratio of 1:1:1 as plastic raw materials, and mix waste oil and heavy oil at a ratio of 1:1 as oil raw materials. Mix plastic raw materials and oil raw materials in a ratio of 1:1 and continuously add them to the pyrolysis reactor, start the stirrer (rotating speed is 20 rpm), and start heating, control the heating rate at 200°C/h, when the cracking temperature reaches 380 ℃, the reaction product begins to crack, and a large amount of colorless gas emerges (for C ₁ -C ₄ gaseous hydrocarbons), and the cracking temperature is controlled between 370°C and 390°C. Collect the reaction cracked gas and send it to the condensing device for condensation. The condensed cracked gas is sent to the catalytic reforming device (equipped with HC-1 molecular sieve catalyst) for catalytic reforming, and then enters the condenser for condensation after catalytic reforming. After condensation, the Liquid oil and gas products. The liquid oil is sent to the rectification device for fractionation. After fractionation, products such as gasoline, diesel oil, and heavy oil are obtained, weighed, and their yields are calculated. The heavy oil is returned to the cracking reactor as the reaction raw material, and the gas product is introduced into the gas bag for storage. The residue produced by coking during the reaction is left in the cracking reactor and weighed to obtain the residue yield. The gasoline quality is analyzed by gas chromatography-mass spectrometer to obtain the distribution of various hydrocarbons.

The difference between the reaction products was compared by using oil and plastic mixed pyrolysis and plastic pyrolysis alone. Table 1 is a comparison of the yields of each product obtained by cracking at 380°C and catalytically upgrading at 320°C, when oil and plastic are cracked alone and when they are cracked together (mixing ratio is 1:1). The pyrolysis of waste oil produces a large amount of non-condensable gas (mainly C ₁ ~ C ₄ compounds), and the yield of liquid products from plastic cracking alone is high, reaching 87.88%; the liquid yield of oil cracking alone is 75.64%; The yield of liquid product was 90.6%. It can also be seen from Table 2 that the amount of residue remaining in the mixed pyrolysis is less than that of plastic pyrolysis, which means that the mixed cracking is beneficial to reduce coking. It can be seen that mixed cracking can not only make full use of waste oil and heavy oil, but also obtain more useful substances (gasoline and diesel oil) and reduce coking.

Table 1 The difference between mixed cracking and thermal cracking

Materials Liquid Yield % Gasoline Fraction % Diesel Fraction % Heavy Oil Fraction % Cracked Gas % Residue %

Waste oil 75.64 14.37 35.38 25.89 23.34 1.02

Waste plastic 87.88 31.78 44.79 11.31 7.39 4.73

Waste plastic + waste oil 84.46 30.34 39.36 14.76 12.56 2.98

Waste plastic + heavy oil 83.29 27.59 39.15 16.55 13.58 3.13

Waste plastic + heavy oil + waste oil 90.60 32.05 45.05 13.50 8.05 1.35

The gasoline products of the two were analyzed by gas chromatography-mass spectrometry to obtain the contents of each component, as shown in Table 2. There are more light components (C6-C9) in the mixed pyrolysis gasoline components; and more heavy components (C9-C12) in the individual pyrolysis of plastics.

            Table 2 Comparison of the results of each component in gasoline obtained from mixed pyrolysis and plastic pyrolysis alone

Gasoline in mixed cracking Plastic in separate cracking Gasoline in mixed cracking Plastic in separate cracking

Component Content of each component/% Content of each component/% Component Content of each component/% Content of each component/%

C ₄ ~C ₅ 5.87 3.95 C ₉ 31.36 34.09

C ₆ 21.43 13.22 C ₁₀ ~C ₁₁ 1.84 11.37

C ₇ 19.89 9.36 C ₁₂ 5.45 13.28

C ₈ 12.49 11.57 C ₁₃ ~C ₁₅ 1.67 3.16

From the table, it can be calculated that the gasoline octane number of mixed cracking is 91.38, and the gasoline octane number of single cracking is 84.28. Gasoline quality has been significantly improved.

Example 2:

The actual demonstration project of preparing liquid fuel by mixed pyrolysis of waste plastics, heavy oil and waste oil is carried out according to the process flow shown in Figure 1. The device can process 1 ton of waste plastic per hour.

Waste plastics are processed by a bulldozer to remove soil, stones, and metal. The processed mixed waste plastics contain polyethylene, polypropylene, polystyrene and a small amount of other substances. After mixing polyethylene, polypropylene and polystyrene in a ratio of 1.1:1.3:0.8, they are fed into the pyrolysis reactor through the screw conveyor 1 3, at the same time, add the waste oil and heavy oil mixed in the ratio of 0.8:1.2 to the waste oil and heavy oil preheating kettle 2, and add the waste plastic raw material to the oil raw material in the ratio of 1.3:0.9 to the pyrolysis reactor 3 for mixing . The agitator 32 of the cracking reactor 3 runs at a speed of 20 rpm, and starts heating, and controls the heating rate at 210°C/h. When the cracking temperature reaches 380°C, the reaction product starts to crack, and a large amount of colorless gas emerges (for C ₁ -C ₄ gaseous hydrocarbons), control the cracking temperature between 375°C and 395°C. The waste plastics are fully cracked in the fixed bed reactor 31 of the reactor 3 (see FIG. 2 ). All the cracked gas enters the cyclone separator 4 from the output pipe for dust removal and separation, wherein the heavy components and dust are returned to the cracking reactor 3 . Gasoline and diesel steam is cooled by cooler 5 and then enters catalytic reforming reaction tower 6 (the catalytic tower is equipped with HC-1 molecular sieve catalyst) for catalytic reforming to make isomerization, cyclomerization and aromatization. Then enter the rectification tower 7 for refined fractionation. The oil gas after rectification enters the condenser 8, is condensed and liquefied, and then enters the intermediate cylinder for storage. The remaining non-condensable gas is sent into the steam cabinet by the fan, and compressed by the compressor 9. Preheating with heavy oil provides combustion steam. The gasoline and diesel oil in the intermediate tank is filtered by the refining tank and then pressed into the finished product storage tank. The heavy oil is circulated as a raw material and re-enters the waste oil and heavy oil preheating tank 2. After preheating, it enters the cracking reactor 3 for re-reaction. Cracked carbon black and dust are discharged by the slag remover 33 of the cracking reactor 3.

In this embodiment, the waste plastics come from waste plastic woven bags, waste food bags, waste packaging materials, waste scraps after industrial production, and the components are PE, PP and PS. The amount of waste plastics is 500kg/h, the amount of waste oil and heavy oil is 500kg/h, the amount of reforming catalyst HC-1 is 100kg, and the catalytic reforming temperature is 320°C. This device realizes continuous feeding and continuous slag discharge.

The main indicators of gasoline and diesel produced by this device and catalyst fully comply with China's national motor gasoline standard (GB484-93) and motor diesel standard (GB252-93), which not only has huge environmental and social benefits, but also There are also very good direct economic benefits.

Claims (3)

1. one kind is utilized plastic waste, waste oil and heavy oil mixed pyrolysis are produced the method for oil fuel, it is characterized in that: with heavy oil, waste oil is as oily raw material by weight after 0.5～1.5: 0.5～1.5 the mixed, be to add in the cracking reactor continuously after 1～3: 1～3 the mixed by weight with plastic raw materials and oily raw material, rotating speed with 10～30rpm starts agitator and begins heating, the control heat-up rate is at 150～250 ℃/h, and control cracking temperature to 370～450 ℃, collect the reaction splitting gas and use the catalyzer upgrading, splitting gas behind upgrading obtains liquid oil and gaseous product through condenser, liquid oil obtains gasoline through fractionation again, diesel oil, heavy oil, as reaction raw materials, gaseous product is collected and is stored in the heavy oil Returning reactor; Described plastic raw materials is a mixed waste plastic, and be 0.5～1.5: 0.5～1.5 by weight by polyethylene, polypropylene, polystyrene: 0.5～1.5 mixed forms.

2. the method for utilizing plastic waste, waste oil and heavy oil mixed pyrolysis to produce oil fuel according to claim 1, it is characterized in that: the oily liquids material that described waste oil is mixed by arbitrary proportion by waste vapour oil, waste diesel, useless base oil, described heavy oil is the long-chain macromolecule amount high viscosity oil product that produces in the process of oil production.

3. the method for utilizing plastic waste, waste oil and heavy oil mixed pyrolysis to produce oil fuel according to claim 1 and 2 is characterized in that: described catalyzer is HY, Ni-REY, HZSM-5, HC-1 molecular sieve catalyst, or modifying catalyst SiO ₂/ Al ₂O ₃In any.

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