WO2016034739A1

WO2016034739A1 - A mineral additive, in particular for application in the continuous processing of waste plastics, a method which uses the said additive and an apparatus for carrying out the method

Info

Publication number: WO2016034739A1
Application number: PCT/EP2015/070364
Authority: WO
Inventors: Marcin LUNIEWSKI; Piotr KONCEWICZ
Original assignee: Realeco Sp Z OO
Current assignee: Realeco Sp Z OO
Priority date: 2014-09-05
Filing date: 2015-09-07
Publication date: 2016-03-10
Anticipated expiration: 2017-03-05
Also published as: PL409381A1; PL229433B1

Abstract

The object of the invention is a mineral additive, in particular for application in continuous processing of waste plastics consisting in melting the polymer feedstock formed thereof in the form of chaff, granules or agglomerates, subjecting the resulting phase to the pyrolysis process taking place in the extruder (6) and then in the reactor (1) in which hydrocarbon product is formed, characterized in that a fraction with a grain size in the range of 0.1 to 1 mm is at least 80% by weight of the additive, preferably 90% by weight of the additive. The object of the invention is also a method which uses this additive and an apparatus for carrying out the method.

Description

A mineral additive, in particular for application in the continuous processing of waste plastics, a method which uses the said additive and an apparatus for carrying out the method

The object of the invention is a mineral additive, in particular for application in continuous processing of waste plastics consisting in melting the recirculated material formed thereof in the form of chaff, granules or agglomerates, subjecting the resulting phase to the pyrolysis process taking place in the extruder and then in the reactor in which hydrocarbon product is formed. The object of the invention is also a method which uses this additive and an apparatus for carrying out the method.

Methods of processing waste plastics are known in the prior art. For example patent specification PL178639 discloses a method for processing the old and waste plastics, consisting in the depolymerisation of feedstocks to a pumpable and volatile phase. In this process, after completed depolymerisation, the volatile phase is separated into a gas phase and a condensate which is subjected to standard refining, while the pumpable phase, after separation of the volatile phase, is subjected to hydrogenation, low-temperature gasification or a combination of these processes. The described depolymerisation method is a catalytic process taking place under the conditions of turbulent flow in the presence of an inert gas containing waste solvents, waste oils or fractions of petroleum refining.

An alternative method of processing waste plastics, consisting in thermal or catalytic cracking in the presence of a catalyst from a group of aluminosilicates, is presented in the patent specification PL191650. Gaseous and liquid products obtained from the cracking, immediately after the pyrolysis, are directed to an evaporator, where they are mixed with hydrogen and then the steam-gas mixture is transferred directly into the reactor. In the reactor olefinic compounds contained in the

l hydrogen - hydrocarbon mixture are hydrogenated using typical hydrogenation catalysts: palladium or platinum on solids tungsten - nickel and molybdenum - nickel on solids.

Polish patent application PL339821 discloses also a method for producing a mixture of aliphatic hydrocarbons from a mixture waste plastics, consisting in thermal decomposition of the feedstock. The mixture of waste thermoplastics, after separating the buoyant fraction in water and after a possible preliminary treatment, is heated to a temperature of 320 - 450°C under a pressure of 0.008 - 3.5MPa, and then is distilled, and the resulting product is separated and purified.

A method of continuous processing of waste plastics, especially of polyolefin type, is presented in Polish patent application PL352341 , according to which the process of thermocatalytic destruction is carried out continuously, and the plasticized feedstock is formed in the heat exchanger into the form of a homogeneous spinal column, falling by gravity, liquefied from the bottom of and dispensed into the reactor (stabilizer).

Another embodiment of the thermocatalytic destruction process of waste plastics is disclosed in a description of the invention PL191341 , according to which the known process of thermodegradation of polyolefin wastes is carried out at a temperature of 250 - 450°C in the presence of a catalyst from the group of aluminosilicates, with a separation of the resultant products by fractional condensation and recycling to the process of gaseous side products being the source of heat. Feedstock in solid or liquid form introduced into the reactor is mixed with technological oil in a weight ratio of 100 - 1 :1 , whereas the catalyst is fed to the reactor as a suspension in technological oil in the amount from 0.1 to 5% by weight relative to the amount of material. In turn, feedstock in the form of a suspension of ground or granulated waste is in the amount from 1 to 20% by weight relative to the technological oil.

A method of thermal destruction of waste plastics is described in the application WO 95/03375. It involves melting the plastics before feeding them into the reactor, where degradation takes place at 400-550°C. It is proposed to re-introduce a low boiling fraction separated by distillation from the decomposition products into the reactor. Despite a number of known solutions in the scope of waste management of plastics in the way of their thermal decomposition, a large part of them have drawbacks that significantly limit their usefulness. The most important ones include the problem of removing solid reaction products on a continuous basis without interrupting the process. In most of the known solutions, it is necessary to use maintenance shut-downs necessary to remove the resulting solid products. This operation significantly reduces the efficiency of the plant and significantly reduces its energy efficiency. Another limitation of known plants is their size, and thus the inability to carry them as close to the sites of the formation or accumulation of waste plastics as possible. The possibility of a quick and cheap change of the plant location may be an important factor determining the cost-effectiveness of the proposed management method of waste plastics.

The aim of the invention is therefore to provide an improved process for the thermal processing of waste plastics that would facilitate the removal of solid reaction products on a continuous basis without interrupting the process.

Surprisingly, it turned out that feeding a mineral additive of appropriate grain size into the process significantly improves the efficiency of removing solid products formed in the process.

The object of the invention is a mineral additive, in particular for application in the continuous processing of waste plastics consisting in melting the recirculated material formed thereof in the form of chaff, granules or agglomerates, subjecting the resulting phase to the pyrolysis process taking place in the extruder and then in the reactor in which hydrocarbon product is formed, characterized in that it comprises a fraction with a grain size in the range of 0.1 to 1 mm, which is at least 80% by weight of the additive, preferably at least 90% by weight.

Preferably, a fraction with a grain size up to 1 mm is 100% by weight of the additive.

Preferably, the additive is a catalyst for polymer feedstock pyrolysis process.

Preferably, the additive comprises metals and/or metal oxides and/or metal aluminosilicates. The object of the invention is also a method of thermal processing of waste plastics, wherein the polymer feedstock, preferably in the form of chaff, granules or agglomerates is fed into the reactor, preferably through an extruder, in which extruder the feedstock gains plasticity and the pyrolysis process starts, wherein after feeding the feedstock into the reactor pyrolysis process is carried leading to the formation of hydrocarbon product, characterized in that during the pyrolysis process solid products of pyrolysis are condensed on the mineral additive according to any one of the preceding claims, and then the condensation products are sedimented and agglomerated.

Preferably, the mineral additive is fed into the system along with the polymer feedstock.

Preferably, the mineral additive is 1 -15% by weight, preferably less than 10% of the feed comprising the additive and polymer feedstock.

Preferably, from 0 to 50% by weight of the mineral additive is replaced by an addition to the feedstock in the form of a solid product discharged from the process, after grinding to grain size of less than 1 mm and fraction in the range of 0.1 to 1 mm greater than 80% by weight.

Preferably, in the area of the discharging solid products, the movement direction of the polymer feedstock changes.

Preferably, the process is carried out continuously.

Preferably, the solid product is discharged from the reactor continuously.

Preferably, the rate of discharging solid products from the reactor and adding the additive is selected so that the softening point of the solid product is not less than 50°C, preferably 51 -60°C.

The object of the invention is also an apparatus for continuous thermal processing of waste plastics comprising a raw material dosing system, preferably an extruder, wherein the pyrolysis process starts, decomposition reactor, wherein the formation of the hydrocarbon product takes place, equipped with mixing elements and a system of receiving and separating the products, characterized in that at least one mixing element located in the reactor in the area of discharging solid products is adapted to changing the movement direction of the reaction mixture. Preferably, the apparatus comprises the means for discharging the solid product in a continuous manner.

Preferably, the apparatus is made in a container housing.

Feeding the mineral additive of appropriate grain size into the process significantly improves the efficiency of removing solid products formed in the process because in the reactor they condensate on the particles of the fed additive, and then their sedimentation and agglomeration takes place, which allows easier discharging of agglomerated solid product from the reactor in a continuous manner. The mineral additive significantly improves the homogenisation of the feedstock and facilitates the transfer of heat which is necessary for the reaction. Consequently it causes the formation of smaller temperature gradients in the reaction mixture and reduces the separation of solid products of the reaction.

Selecting the softening point of the solid product so as to be less than 50°C, preferably 51 -60°C, allows for the use of the discharged solid product as a component of bitumen.

Changing the movement direction of the reaction mixture in the receiving area for solid products in the reactor allows to increase the residence time in the reactor and to increase the efficiency of agglomeration of the solid products on the particles of the mineral additive.

Continuous discharge of solid reaction products helps to avoid maintenance shut-downs necessary to remove the resulting solid products which significantly impair the capacity of the system and significantly reduce its energy efficiency.

Execution of the apparatus in a container housing gives the possibility of a quick and cheap change of the plant location without dismantling and building a permanent infrastructure at the site of operation.

The invention will now be further illustrated in the preferred embodiment, with reference to the accompanying drawings, in which: Fig. L is a schematic diagram of an apparatus for the thermal processing of waste plastics

Fig. 2 is a schematic diagram of the mixing elements in the area of discharging solid products

Example 1

An apparatus for the continuous thermal processing of waste plastics consists of a system of dosing raw material in the form of chaff, granules or agglomerates along with the mineral additive, an extruder in which the feedstock gains plasticity and the pyrolysis process starts, a decomposition reactor equipped with mixing elements wherein the formation of the hydrocarbon product takes place and a system of receiving and separating products, and an automatic control system. In the reactor, the solid products formed in the process condensate on the particles of the catalyst fed and then their sedimentation and agglomeration take place, and the agglomerated solid product is discharged in a continuous manner from the reactor.

An apparatus for continuous thermal processing of waste plastics is shown in fig. 1 . It consists of a thickener 7 into which raw material in the form of chaff, granules or agglomerates is fed along with the mineral additive, an extruder 6 in which the feedstock gains plasticity and the pyrolysis process starts, a decomposition reactor 1 equipped with mixing elements 2 wherein the formation of the hydrocarbon product takes place. The volatile products 9 emerge from the reactor 1 to the condenser 8, from which, after cooling, they are transported by gravity to the intermediate tank 11 . Periodically, the intermediate tank 11 is emptied and the liquid products are transported via the light and medium oil fraction pump 13 into the light and medium oil fraction collecting tank 12. The ingredients not undergoing condensation are discharged through the degassing system 3 and used for energy purposes of the plant. The solid products of the process are removed in a continuous manner 4 and deposited 5. Then, some of them after grinding are fed to the thickener, together with the polymer feedstock. The condenser is equipped with a heat removal system comprising a fan 10, a coolant pump 14 and a heat exchanger 15. The mixing elements 2 in the area of separating solid products, shown in fig. 2, are adapted for changing the movement direction of the reaction mixture prolonging the residence time in the reaction zone. Recycling the reaction mixture is provided by modified geometry or rotation direction of the mixing elements in the area of separating the solid products in relation to other mixing elements.

The apparatus is made in a container housing allowing transportation without disassembling the apparatus and location without having to build a permanent infrastructure at the site of operation through powering by generators using part of the resulting volatile products.

Example 2

The extruder was fed raw material having an average composition of: 67% of polyethylene, 18% of polypropylene, 5% of polystyrene and 10% of a mineral additive in the form of halloysite containing 90% of a fraction of 0.1 -1 mm at a rate of 120 kg/h. The molten reaction mixture at a temperature of 380°C was fed into the reactor maintained at a temperature of 430°C. After 30 min. from the beginning of the dispensing, condensation of liquid products began at a rate of 109 kg/h. The properties of the resultant liquid product are presented in Table 1 .

Table 1

A solid product was discharged from the reactor at a rate of 6 kg/h and was characterized by a softening point of 58°C.

Example 3

The extruder was fed raw material having an average composition of: 67% of polyethylene, 18% of polypropylene, 5% of polystyrene and 10% of a mineral additive in the form of a natural zeolite containing 92% of a fraction of 0.1 -1 mm at a rate of 200 kg/h. The molten reaction mixture at a temperature of 365°C was fed into the reactor maintained at a temperature of 415°C. After 30 min. from the beginning of the dispensing, condensation of liquid products began at a rate of 184 kg/h. The properties of the resultant liquid product are presented in Table 2.

Table 2

A solid product was discharged from the reactor at a rate of 9.5 kg/h and was characterized by a softening point of 60°C.

These examples relate to the processes implemented for the additive with a fraction of 0.1 -1 mm, of 90 and 92% by weight. Research has indicated beneficial effect of fraction 0.1 -1 mm in a much broader scope, i.e. 80%.

Claims

1. A mineral additive, in particular for application in the continuous processing of waste plastics consisting in melting the polymer feedstock formed thereof in the form of chaff, granules or agglomerates, subjecting the resulting phase to the pyrolysis process taking place in the extruder (6) and then in the reactor (1 ) in which hydrocarbon product is formed, characterized in that it comprises a fraction with a grain size in the range of 0.1 to 1 mm, which is at least 80% by weight of the additive, preferably at least 90% by weight of the additive.

2. A mineral additive according to claim 1 , characterized in that a fraction with a grain size up to 1 mm is 100% by weight of the additive.

3. A mineral additive according to claim 1 or 2, characterized in that it is a catalyst for the polymer feedstock pyrolysis process.

4. A mineral additive according to claim 1 or 2 or 3, characterized in that it comprises metals and/or metal oxides and/or metal aluminosilicates.

5. A method of thermal processing of waste plastics, wherein the polymer feedstock, preferably in the form of chaff, granules or agglomerates, is fed into the reactor (1 ), preferably through the extruder (6), in which extruder the feedstock gains plasticity and the pyrolysis process starts, wherein after feeding the feedstock into the reactor (1 ) the pyrolysis process is carried out leading to the formation of hydrocarbon product, characterized in that during the pyrolysis process solid products of pyrolysis are condensed on the mineral additive according to any one of the preceding claims, and then the condensation products are sedimented and agglomerated.

6. A method according to claim 5, characterized in that a mineral additive is fed into the system along with the polymer feedstock.

7. A method according to claim 5 or 6, characterized in that a mineral additive is from 1 to 15% by weight, preferably less than 10% of the feedstock comprising the additive and polymer feedstock.

8. A method according to claim 5 or 6 or 7, characterized in that from 0 to 50% by weight of a mineral additive is replaced by the addition to the feedstock in the form of a solid product discharged from the process, after grinding to a grain size below 1 mm and a fraction in the range of 0.1 to 1 mm greater than 80% by weight.

9. A method according to any one of claims 5 to 8, characterized in that in the area of the discharging solid products, the movement direction of the polymer feedstock changes.

10. A method according to any one of claims 5 to 9, characterized in that it is carried out continuously.

11. A method according to any one of claims 5 to 10, characterized in that the solid product is discharged from the reactor (1 ) continuously.

12. A method according to claim 11 , characterized in that the rate of discharge of solid products from the reactor (1 ) and adding the additive is selected such that the softening point of the solid product is not less than 50°C, preferably 51 -60°C.

13. An apparatus for continuous thermal processing of waste plastics comprising a polymer feedstock dosing system, preferably an extruder (6), wherein the pyrolysis process starts, decomposition reactor (1 ), wherein the formation of the hydrocarbon product takes place, equipped with mixing elements (2) and a system of receiving and separating the products (3, 8, 10, 11 , 12, 13, 14, 15), characterized in that at least one mixing element (2) located in the reactor (1 ) in the area of discharging of products is adapted to changing the movement direction of the reaction mixture.

14. An apparatus according to claim 13, characterized in that it comprises the means for discharging the solid product (4) in a continuous manner.

15. An apparatus according to claim 13 or 14, characterized in that it is made in a container housing.