BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to recycling treatment, and more particularly to plastic recycling system and method thereof.

Description of Related Arts

Plastic products are widely used in daily life, but how to deal with the plastic waste afterwards is a difficult problem. The traditional methods include landfill, incineration and recycled granulation. Plastic waste is buried underground and expected to be naturally degraded after hundreds of year. This is apparently not an appropriate way to treat plastic waste.

As stated above, there are three traditional methods of treating plastic waste, including landfill, incineration and recycled granulation. Landfill is a treatment that plastic waste is buried underground and expected to be naturally degraded after hundreds of years. In fact, plastic waste is hardly to be degraded in the natural environment but will merely become micro particles spreading everywhere that causes a secondary pollution to the environment. Incineration is a treatment to directly combust the plastic containing mainly compositions of hydrocarbons. However, during the combustion process, plastic will release a large amount of harmful substances, such as dioxin. Recycled granulation refers to the crushing of the plastic waste into particles by means of mechanical process and then re-making such particles into recycling plastic products. However, the application scope of such recycled granulation is limited, wherein high-quality plastic products can be processed recycled granulation to produce poor quality recycling plastic products, while poor-quality plastic products are difficult to process recycled granulation.

In addition, there is another common way of plastic recycling treatment by means of pyrolysis, i.e. decomposition brought about by high temperatures, to decompose plastic formed by the polymerization of multiple molecules into small molecular hydrocarbon compounds. Specifically speaking, the plastic wastes are contained in a reaction container and thermal energy is provided to heat the reaction container, wherein petroleum or natural gas is generally used as fuel to provide heat at the bottom of the reaction container, so that the plastic wastes in the reaction container are melted and then gasified and pyrolyzed into a variety of small hydrocarbon compounds. During such pyrolysis process, the temperature and pressure of the reaction container are required to be accurately controlled, wherein either the temperature of the reaction container is too high or too low will adversely affect the reacting plastic and the efficiency of the whole process. However, it is apparent that the control of the supplying heat through fuel combustion is relatively difficult and oxygen in the air is required in the fuel combustion process, that spontaneously gathers oxygen in the air around the reaction container. Therefore, once any of the hydrocarbon products in the reaction container under high temperature leaks out, it is easy to trigger an explosion.

In order to ensure the heat generated at the bottom portion of the reaction container can be transferred to the entire reaction container and, at the same time, to avoid any contact of the reactants in the reaction container with outside air, the reaction container must be remained in a sealed condition during the pyrolysis process until the reaction is completed. During the gasification process, the pressure in the entire reaction container will be increased sharply and the operator outside the reaction container is unable to directly observe the progress of the reaction inside the reaction container, so the reaction time is generally extended to ensure a complete reaction. In other words, the conventional plastic recycling method by pyrolysis is not only dangerous in safety concern but also difficult to be safely controlled, resulting in relatively low operation efficiency.

SUMMARY OF THE PRESENT INVENTION

The invention is advantageous in that it provides a plastic recycling system and method thereof adapted for thermal decomposition process, such as pyrolysis, for plastic material while it can be precisely controlled throughout the process.

Another advantage of the invention is to provide a plastic recycling system and method thereof, which can provide a more safe and reliable environment for thermal decomposition and pyrolysis of plastic.

Another advantage of the invention is to provide a plastic recycling system and method thereof, wherein the temperature of both the plastic gasification environment and plastic pyrolysis environment can be more precisely controlled, so that the expected product(s) can be obtained.

Another advantage of the invention is to provide a plastic recycling system and method thereof, wherein the reaction temperature of the different positions in a reaction unit can be more precisely controlled so as to obtain predetermined end product(s), wherein the reaction unit has a lower space portion adapted for plastic gasification and an upper space portion adapted for plastic pyrolysis.

Another advantage of the invention is to provide a plastic recycling system and method thereof, which do not require any fuel and oxygen in air to process combustion for producing heat to the reaction unit of the plastic recycling system, so that the plastic recycling system of the present invention will not gather oxygen in air there and generate carbon dioxide resulted in fuel combustion.

Another advantage of the invention is to provide a plastic recycling system and method thereof, which includes a reaction unit having a lower space portion adapted for plastic gasification and an upper space portion adapted for plastic pyrolysis, wherein the producing of heat for the upper space portion and the lower space portion can be controlled independently.

Another advantage of the invention is to provide a plastic recycling system and method thereof, which includes a reaction unit having a lower space portion adapted for plastic gasification and an upper space portion adapted for plastic pyrolysis, wherein the heat applied to the upper space portion and the lower space portion can be produced independently.

Another advantage of the invention is to provide a plastic recycling system and method thereof, wherein a heating unit that converts electricity into heat to produce thermal energy is provided to heat the reaction unit, wherein the heating unit can be arranged around the reaction unit upon predetermined demands instead of being limited to heat the bottom portion of the heating unit as in the conventional fuel combustion method.

Another advantage of the invention is to provide a plastic recycling system and method thereof, wherein each of plastic gasification environment and the plastic pyrolysis environment can be arranged with the heating unit independently, so that the reaction unit does not need to rely on traditional fuel combustion method that uses air convection to transmit heat, and thus the sealing requirement for the reaction unit can be reduced.

In accordance with another aspect of the invention, the present invention provides a plastic recycling method comprising the following steps:

(a) heating plastic waste in a reaction unit by at least one heating unit that converts electricity into heat to thermally decompose the plastic waste to produce at least a decomposed product, including fuel in gas phase, and

(b) condensing the gas phase decomposed product to useable liquid phase fuel product.

In one embodiment, the step (a) further comprises the steps of heating the reaction unit with a gasification heating module to gasify the plastic in the reaction unit to gasified plastic, and then heating the gasified plastic by a decomposition heating module to decompose and split the gasified plastic in the reaction unit.

In one embodiment, the step (a) further comprises a step of transmitting or delivering the gasified plastic from a gasification module of the reaction unit to a decomposition module of the reaction unit for decomposition such as pyrolysis by operationally connecting the gasification module with the decomposition module

In one embodiment, in the step (a), the gasification module is heated to the predetermined temperature by the gasification heating module of the heating unit and the decomposition module is heated to the predetermined temperature by the decomposition heating module of the heating unit.

In one embodiment, in the step (a), when the temperature of the decomposed product before leaving the decomposition module is lower than the predetermined temperature, the decomposed product is kept in or transmitted back to the decomposition module in order to continue to be heated to reach the predetermined temperature.

In one embodiment, in the step (a), the plastic contained at the lower portion of the reaction unit is heated by the heating unit arranged around the lower portion of the reaction unit and gasified to flow upwardly to the upper portion of the reaction unit for decomposition such as pyrolysis.

In one embodiment, the plastic recycling method further comprises the following steps after the step (a) and before the step (b):

(i) filtering the decomposed product by a filtration unit, and

(ii) transmitting the filtered decomposed product to a condensation unit for processing the condensing step (b).

In one embodiment, the plastic recycling method further comprises the following steps after the step (b):

collecting the liquid phase fuel product,

delivering a portion of the liquid phase fuel product to an electric power generation unit to generate electricity supplying the heating unit, wherein the electric power generation unit is electrically connected to the heating unit.

In one embodiment, in the step (a), wherein the decomposition module of the reaction unit is heated and controlled at the predetermined temperature ranged from 80° C. to 120° C. for plastic pyrolysis and decomposition.

In one embodiment, in the step (a), the gasification module of the reaction unit is heated and controlled at the predetermined temperature ranged from 380° C. to 440° C. for plastic gasification.

In accordance with another aspect of the invention, the present invention provides a plastic recycling system arranged for plastic recycling, which comprises:

at least a heating unit;

at least a reaction unit, wherein the heating unit is arranged to provide thermal energy to the reaction unit to heat the plastic disposed in the reaction unit by the thermal energy provided by the heating unit which converts electricity to the thermal energy, wherein the plastic is heated by the heating unit to be pyrolyzed to produce at least a decomposed product in the reaction unit, wherein the decomposed product includes a gas phase fuel product; and

a condensation unit which is operationally connected with the reaction unit, wherein the condensation unit converts at least a portion of the decompose product from the reaction unit into a liquid phase fuel product.

In one embodiment, the plastic recycling system further comprises a filtration unit which is operationally connected with the condensation unit for filtering the decomposed product.

In one embodiment, the heating unit is arranged at a bottom portion of the reaction unit to supply heat thereto, wherein, initially, the plastic is disposed in a lower space portion of a sealable reaction chamber of the reaction unit, so that when the plastic disposed in the lower space portion of the reaction chamber of the reaction unit is heated to a predetermined temperature, the plastic is gasified and flows towards an upper portion of the reaction unit where the gasified plastic is decomposed to obtain the decomposed product in gas phase.

In one embodiment, the heating unit comprises a gasification heating module and a decomposition heating module, wherein the gasification heating module is arranged to provide heat to at least a first portion of the reaction unit to gasify the plastic contained in the reaction unit, and that the decomposition heating module is arranged to provide heat to at least a second portion of the reaction unit to decompose the gasified plastic.

In one embodiment, the reaction unit comprises a gasification module and a decomposition module operationally connected with the gasification module, wherein after the plastic contained in the gasification module is gasified, the gasified plastic is transmitted to the decomposition module wherein the gasified plastic is decomposed to obtain the decomposed product in gas phase.

In one embodiment, the heating unit comprises a gasification heating module and a decomposition heating module, wherein the gasification heating module is arranged to provide heat to gasify the plastic contained in the gasification module, and the decomposition heating module is arranged to provide heat to decomposed the gasified plastic in the decomposition module, wherein the gasification heating module and the decomposition heating module are independently controlled.

In one embodiment, the decomposition module is positioned on top of the gasification module to form a sealable reaction chamber of the reaction unit in combination, wherein an inner space in the gasification module forms the upper space portion of the reaction chamber and an inner space in the decomposition module forms the lower space portion of the reaction chamber, wherein the plastic gasified in the gasification module flows upwardly to the decomposition module for decomposition process such as pyrolysis.

In one embodiment, the gasification module and the decomposition module of the reaction unit are connected through at least one transmission channel, wherein the gasified products obtained in the gasification module is transmitted to the decomposition module through the at least one transmission channel.

In one embodiment, the decomposition module has a sealable decomposing reaction chamber and at least one circulation channel, wherein an inlet of decomposing reaction chamber is operatively linked to a circulation outlet passage of the at least one circulation channel, and an outlet of decomposing reaction chamber is operatively linked to a circulation inlet passage of the at least one circulation channel, wherein when a temperature of the gasified decomposed product that is going to emit through the outlet of the at least one circulation channel and deliver to the condensation unit is lower than the predetermined temperature, the outlet of decomposing reaction chamber used to be connected to the condensation unit is reconnect to the circulation inlet passage of the at least one circulation channel, such that the gasified decomposed product is directed to transmit through the at least one circulation channel and back to the decomposing reaction chamber for further heating.

In one embodiment, the plastic recycling system further comprises an electric power generation unit which is electrically connected with the heating unit for electrically power supply and is operationally connected with the condensation unit, wherein at least a portion of the decomposed product in the condensation unit is recycled to the electric power generation unit for combustion to produce electricity supplying to the heating unit for producing heat energy.

