CA3022018A1 - Plasma arc carbonizer - Google Patents

Abstract

A system and method for plasma arc anaerobic thermal conversion processing is provided to convert waste into bio-gas; bio-oil; carbonized materials; non-organic ash, and varied further co- products. The system and process supports a variety of processes, including to make, without limitation, carbon, carbon-based inks and dyes, activated carbon, aerogels, bio-coke, and bio-char, as well as generate electricity, produce adjuncts for natural gas, and/or various aromatic oils, phenols, and other liquids, all depending upon the input materials and the parameters selected to process the waste, including real time economic and other market parameters which can result in the automatic re-configuration of the system to adjust its output co-products to reflect changing market conditions. Plasma arc carbonizer off-gases produced during carbonization are supplied to a controlled heated column for refining and recovery of the carbonizer hot gases into distillates.

Description

PLASMA ARC CARBONIZER
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority of United States Provisional Patent Application Serial No. 62/360,141 filed July 8, 2016, which is incorporated herein by reference.
FIELD OF THE INVENTION

[0002] The present invention in general relates to a system for converting waste into useful co-products, including hydrocarbon based gases, hydrocarbon-based liquids, and carbonized material; and in particular to carbonation systems using plasma arc units as heating sources.
BACKGROUND OF THE INVENTION

[0003] Pyrolysis is a general term used to describe the thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen.
Pyrolysis differs from other high-temperature processes like combustion and hydrolysis in that it usually does not involve oxidative reactions. Carbonization in these instances operates at less than 5 atomic %
oxygen and typically less than 2 atomic % and is often characterized by irreversible simultaneous change of chemical composition and physical phase.

[0004] Pyrolysis is a case of thermolysis, and is most commonly used for organic materials, and is one of the processes involved in charring. Charring is a chemical process of incomplete combustion of certain solids when subjected to high heat. The resulting residue matter is called char. By the action of heat, charring reductively removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon in a zero-oxidation state. Polymers such as thermoplastics and thermoset, as well as most solid organic compounds like wood and biological tissue, exhibit charring behavior when subjected to a pyrolysis process, which starts at 200-300 C (390-570 F) and goes above 1000 C or 2150 F, and occurs for example, in fires where solid fuels are burning. In general, pyrolysis of organic substances produces gas and liquid products and leaves a solid residue richer in carbon content, commonly called char.
Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization.

[0005] The pyrolysis process is used heavily in the chemical industry, for example, to produce charcoal, activated carbon, methanol, and other chemicals from wood, to convert ethylene dichloride into vinyl chloride to make PVC, to produce coke from coal, to convert biomass into syngas and biochar, to turn municipal solid waste (MSW), and other carbonaceous matter into safely disposable substances, and for transforming medium-weight hydrocarbons from oil into lighter ones like gasoline. These specialized uses of pyrolysis are called by various names, illustratively including dry distillation, destructive distillation, or cracking. Efficient industrial scale pyrolysis has proven to be difficult to perform and requires adjusting reactor conditions to feedstock variations in order to achieve a desired degree of carbonization.

[0006] Converting waste from a liability to an asset is a high global priority. Currently employed technologies rely on incineration to dispose of carbonaceous waste with useable quantities of heat being generated while requiring scrubbers and other pollution controls to limit gaseous and particulate pollutants from entering the environment. Incomplete combustion associated with conventional incinerators and the complexities of operation in compliance with regulatory requirements often mean that waste which would otherwise have value through processing is instead sent to a landfill or incinerated off-site at considerable expense.

Alternatives to incineration have met with limited success owing to complexity of design and operation outweighing the value of the byproducts from waste streams.

[0007] To address this global concern, many methods have been suggested to meet the flexible needs of waste processing. Most of these methods require the use of a waste processing reactor, or heat source, which are designed to operate at relatively high temperature ranges 200-980 C (400 to 2200 F) and allow for continuous or batch processing.

[0008] "Chain Drag Carbonizer, System and Method for the Use thereof' as detailed in U.S.
Patent No. 8,801,904; the contents of which are hereby incorporated by reference, provides an apparatus and process for anaerobic thermal conversion processing to convert waste into bio-gas;
bio-oil; carbonized materials; non-organic ash, and varied further co-products.

[0009] In the technology presented, any carbonaceous waste is converted into useful co-products that can be re-introduced into the stream of commerce at various economically advantageous points. The carbonizer as disclosed has utility to support a variety of processes, including to make, without limitation, carbon, carbon-based inks and dyes, activated carbon, aerogels, bio-coke, and bio-char, as well as generate electricity, produce adjuncts for natural gas, and /or various aromatic oils, phenols, and other liquids, all depending upon the input materials and the parameters selected to process the waste, including real time economic and other market parameters which can result in the automatic re-configuration of the system to adjust its output co-products to reflect changing market conditions.

[0010] "Infectious Waste Disposal" as detailed in Patent Cooperation Treaty Application PCT/US16/13067; the contents of which are hereby incorporated by reference provides a medical waste handling and shredding sub-system with a built-in oxidizer to eliminate potential airborne infectious waste prior to converting the medical waste into useful co-products, including hydrocarbon based gases, hydrocarbon-based liquids, precious metals, rare earths (vaporization temperatures range from about 1200 C to about 3500 C), and carbonized material in a system having as its transformative element an anaerobic, negative pressure, or carbonization system.
The system includes a sealed enclosure that houses a shredder that is fed by a vertical lift and/or a belt conveyor that supplies the infectious waste running from the exterior of the sealed enclosure to the shredder. The shredder further includes a hopper to receive waste and a process airlock where shredded wasted material accumulates and is transferred to the feed conveyor. A
rubberized exterior flap permits containerized and bagged waste to enter the sealed enclosure via the belt conveyor. The sealed enclosure may be maintained at a negative pressure. A thermal oxidizer in fluid communication with the sealed enclosure and a hood acts to destroy any airborne infectious matter from the sealed enclosure and any airborne infectious waste collected by the hood. The thermal oxidizer may be run on a mixture of natural gas and reaction-produced carbonization process gases re-circulated to convert heat through the use of either conventional steam boilers or through Organic Rankin Cycle strategies to operate electrical turbine generators, or in the alternative, to conventional or novel reciprocating engine driven generators. A feed conveyor transfers shredded material from the shredder to a carbonizer.

[0011] Another approach to improve upon the incomplete combustion associated with conventional incinerators is the use of plasma technology. Plasma is a form of ionized gas, where freely flowing electrons give positive or negative charges to atoms, thus making plasma a highly efficient conductor of electricity and generator of heat. The heat generating properties of plasma are utilized in plasma gasification, a process that can break waste down to 1/300th of its original size by using ionized gases to produce temperatures greater than three times the surface temperature of the sun. The plasma gasification process can safely treat almost all forms of hazardous and non-hazardous wastes by breaking down the waste matter into component molecules and producing a synthesis gas (syngas) which can be used as an industrial feedstock to produce biofuels, synthetic fuels, hydrogen, or simply as a fuel (replacing fossil fuels) to generate steam or electricity.

[0012] FIG. 1 illustrates a typical plasma assisted gasification system 10 for treating inputted waste. The inputted waste, which may include any combination of solid, liquid, and gaseous wastes, including both hazardous and non-hazardous wastes is delivered into the feed system 12. Solid waste of the inputted waste is passed through a pre-treatment process where the solid waste is shredded into smaller pieces to prevent blockages in the feed nozzle 14. The waste is then passed through an airlock 16 which prevents gases from escaping into the atmosphere.
The plasma gasifier 18 is an insulated air-tight container with plasma torches 20 at the base of the plasma gasifier 18 to provide the heat required to gasify the waste feed.
The plasma torches 20 consume a very small portion of the total energy available from the feedstock (2-5% of total energy input) in providing part of the heat required to drive the endothermic gasification process.
Partial combustion provides the balance of heat required. Torch power is controlled by an automatic control system, which adjusts the gasification conditions to accommodate the potentially highly variable nature of the feedstock. A plasma arc is contained within the body of the plasma torch 20, and therefore, the waste material is not directly subjected to the plasma arc.
Hence, the classification of the process as plasma assisted gasification.
Nonetheless, the plasma torches 20 facilitate operating temperatures above typical flame temperatures associated with combustion of the waste feedstocks, and also in excess of the melting points of metals and inorganic materials. Either air or oxygen and/or steam is injected above the torches to provide a source of oxygen for the gasification process and control the H2:CO ratio.
Importantly, the gasification occurs in an oxygen starved environment, such that a combustible syngas product is produced, rather than a non-combustible flue gas, which would be the case if all the feed material was combusted.

[0013] Continuing with FIG. 1 any carbon based, or organic molecules that are inside the gasifier 18 become volatilized and are turned into synthesis gas 22 (syngas), which is a mixture of H2, CO, and CO2. Inorganic compounds become vitrified, or melted down and converted into an obsidian like substance, and metals are melted down into a form of slag 24.
An overflow mechanism is used to control the amount of slag 24 available in the chamber at all times, ensuring that enough slag 24 is left to maintain the required high temperatures.

[0014] After leaving the gasifier chamber 18 the syngas 22 passes through a series of filtration systems 26 where the syngas 22 is cooled by using water injection and is filtered of all particulate matter (which can then be fed back into the plasma gasifier). The cooling process acts to prevent the formation of dioxins and furans as these undesirable compounds are known to form within a specific temperature range. The gas will then be reheated to create a series of catalytic reductions to reduce the amount of NOx and convert it into atmospheric nitrogen and water. A series of scrubbers will then remove any acids, chlorides, fluorides, sulphates, phosphates, sodium and calcium.

[0015] A turbine may be connected to the process to generate electricity, which can be used to not only power the plant, but also provide an alternate clean source of renewable power.
Cogeneration also referred to as combined heat and power (CHP) is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat. All thermal power plants emit a certain amount of heat during electricity generation. The heat produced during electrical generation can be released into the natural environment through cooling towers, flue gas, or by other means. By contrast, CHP captures some or all of the by-product heat for heating purposes, or for steam production. The produced steam may be used for process heating, such as drying paper, evaporation, heat for chemical reactions or distillation. Steam at ordinary process heating conditions still has a considerable amount of enthalpy that could be also be used for power generation.

[0016] While there have been many advances in recovering useable byproducts from recycled waste there continues to be a need for further limiting emissions from the recycling and recovery process that further maximizes recovered byproducts. Thus, there exists a need for a process of waste reaction that is efficient to operate to limit environmental pollution in the course of such a conversion, and to produce useful co-products that aid the overall economic value of the process.
SUMMARY OF THE INVENTION

[0017] A system is provided for treating waste, that includes a carbonizer with one or more plasma arc units, where the carbonizer converts the waste to useable products, and resultant hot gases produced from the carbonizer are supplied to a thermal oxidizer.

[0018] A method is provided for treating waste with a plasma arc carbonizer, where the method includes adjusting a set of parameters of the carbonizer based on waste feed stock to be inputted, loading the waste feedstock into the carbonizer; and collecting useable byproducts obtained from the carbonizer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further detailed with respect to the following drawings. These figures are not intended to limit the scope of the present invention but rather illustrate certain attributes thereof.

[0020] FIG. 1 is a prior art functional diagram of a plasma gasification system that converts inputted waste to synthesis gas;

[0021] FIG. 2 is a perspective view of a plasma arc carbonizer with a piston driver for pushing containers of waste into the plasma heating zone in accordance with embodiments of the invention;

[0022] FIG. 3 is a side perspective view of a chain drag carbonizer with plasma arc heating sources in accordance with embodiments of the invention;

[0023] FIG. 4 is a perspective view of a plasma arc carbonizer with a controlled heated column for refining and recovery of carbonizer hot gases; and

[0024] FIG. 5 is a flowchart of a process for refining off-gases that are produced by a carbonizer in accordance with embodiments of the invention.
DESCRIPTION OF THE INVENTION

[0025] An inventive system and method for plasma arc anaerobic thermal conversion processing is provided to convert waste into bio-gas; bio-oil; carbonized materials; non-organic ash, and varied further co-products. In the inventive technology presented herein, any carbonaceous waste is converted into useful co-products that can be re-introduced into the stream of commerce at various economically advantageous points. The present invention has utility to support a variety of processes, including to make, without limitation, carbon, carbon-based inks and dyes, activated carbon, aerogels, bio-coke, and bio-char, as well as generate electricity, produce adjuncts for natural gas, and /or various aromatic oils, phenols, and other liquids, all depending upon the input materials and the parameters selected to process the waste, including real time economic and other market parameters which can result in the automatic re-configuration of the system to adjust its output co-products to reflect changing market conditions. In a specific embodiment of the plasma arc carbonizer, off-gases produced during carbinization are supplied to a controlled heated column for refining and recovery of the carbonizer hot gases. The controlled heated column performs hydro-carbon recycling, and acts as a cracking tower that takes the carbonizer off-gas as a feedstock and distills the off-gases into constituent parts under pressure and temperature conditions where the feedstock evaporates and condenses into a fractional column of distillates. The number of theoretical plates needed to exact a desired level of separation is readily calculated using the Fenske equation.

[0026] Distillates extracted are appreciated to be a function of the chemical nature of the feedstock and the carbonizer conditions. Illustrative distillates include C2-C36 compounds of alkanes, alkenes, ethers, esters, phenols, aromatics, lignins, polycyclics;
and substituted versions thereof where the substituent in place of a hydrogen atom is for example, a hydroxyl, an amine, a sulfonyl, a carboxyl, a halogen, or a combination thereof.

[0027] As used herein, the terms "carbonized material", "carbonaceous product" and "carbonaceous material" are used interchangeably to define solid substances at standard temperature and pressure that are predominantly inorganic carbon by weight and illustratively include char, bio-coke, carbon, activated carbon, aerogels, fullerenes, and combinations thereof.

[0028] It is appreciated that a feedstock is readily treated with a variety of solutions or suspensions prior to carbonizer to modify the properties of the resulting inorganic carbon product. By way of example, solutions or suspensions of metal oxides or metal salts are applied to a feedstock to create an inorganic carbon product containing metal or metal ion containing domains. Metals commonly used to dope an inorganic carbon product illustratively include iron, cobalt, platinum, titanium, zinc, silver, and combinations of any of the aforementioned metals.

[0029] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0030] Since a core element of the inventive process for refining off-gases that are produced by a carbonizer is carbonization, there are a wide variety of possible operating configurations and parameters to adjust product mixes and waste stream throughput. The system is readily re-configured, and system operating parameters changed, some in real time, to adjust co-product outputs and percentages thereof to reflect on-going market conditions. For illustrative purposes, wood, before entering the process, can have its moisture removed, but not so much as to "burst"
the plant cells within the cellular structure of the wood, but rather to rendered contained water as steam and thus destroy the cellular fabric of the wood. The temperature range, duration of exposure, mixing rate, and other factors claimed as part of the inventive process, machine and system of systems herein are thus focused on controlling the many variables inherent in such anaerobic thermal conversion processes in order to produce results with utility for future use as opposed to just destruction.

[0031] System configuration in certain embodiments includes carbonization process heat source generators that are plasma arc units. In a specific embodiment, the plasma arc generators are nitrogen based. Reaction-produced carbonization process gases, if present, may be re-circulated to operate the drag chain reactor motors, used to heat water and generate steam for turbines or steam reciprocating engines or to supply subsequent distillation processes. The re-circulated heat in some inventive embodiments may also be used to preheat feedstock or to produce electricity. The pre-processing heating system preheats feedstock material prior to entering the reactor tube.

[0032] A carbonization system in specific inventive embodiments also utilizes a thermo-chemical reactor which may be a drag-chain reactor, or others such as, but not limited to batch, continuous-stirred-tank, thermal oxidizers, or plug-in reactors.

[0033] Another important element of an inventive system is the use of an air-seal, which not only aids mixing and heat diffusion, but allows pressurization of, or the creation of a partial or complete vacuum within the reactor for various reasons, including preventing gaseous contaminants from escaping the reactor, managing pressures, and managing the flow of gases within the overall reactor and associated processing elements.

[0034] Referring now to the figures, FIG. 2 is a perspective view of a plasma arc carbonizer 30 with one or more plasma arc generators 40, and a piston driver 34 for pushing containers of waste 36 into the plasma heating zone 42 of the sealed enclosure 38. The sealed enclosure 38 may be maintained at a negative pressure. An airlock 32 may be used to introduce the containers of waste 36 into the sealed enclosure 38 to prevent gases from escaping and to maintain the atmospheric conditions within the process chamber of the sealed enclosure 38.
The remaining solids illustratively including metals, glass, and carbon by-products are moved with the piston driver 34 to the drop slot 44 and collected in the bin 46. The collected materials may then be separated, and non-useable by-products may be reintroduced into the plasma arc carbonizer 30 for further processing. A thermal oxidizer 48 in fluid communication with the sealed enclosure 38 acts to destroy any airborne infectious matter and pollutants from the sealed enclosure 38.

[0035] FIG. 3 is a side perspective view of a chain drag carbonizer 50 with one or more plasma arc heating sources 40. Waste is inputted into an airlock 32 that introduces the waste to a shredder 52 that deposits the shredded waste on to a conveyer 56. The conveyer 56 carries the shredded waste into a plasma heated sealed enclosure 54. A thermal oxidizer 48 in fluid communication with the sealed enclosure 54 acts to destroy any airborne infectious matter and pollutants from the sealed enclosure 54.

[0036] FIG. 4 is a block diagram of a plasma heated system 100 with a plasma heated carbonizer 102 with a controlled heated column 104 for refining and recovery of by-products from carbonizer hot gases. The plasma heated carbonizer 102 may perform anaerobic thermal conversion processing with one or more plasma arc generators 40 to generate heat that converts input (arrow Al) illustratively including, but not limited to municipal solid waste, infectious medical waste, and bitumen into useable products (arrow A8) such as bio-gas;
bio-oil;
carbonized materials; non-organic ash. Non-useable output (arrow A9) from the plasma heated carbonizer 102 may either be safely disposed of, or recirculated back into the carbonizer 104 for further processing. The plasma heated carbonizer 102 may be operative with a controlled heated column 104 for refining and recovery of by-products from carbonizer hot gases as detailed in U.S.
Patent No. 8,801,904. Hot gases (arrow A2) generated by and in the carbonizer 102 are feed to the controlled heated column(s) 104 for hydro-carbon re-cycling (cracking).
Temperature cut points (zones) within the controlled heated column 104 are signified by outputs 106A-106D that supply distillates represented by arrows A3, A4, and AS. Remaining hot gases or solids (arrow A6) that do not distill out as a useable by-product may either be further scrubbed and safely disposed of, or recirculated (arrow A7) into the carbonizer 102 for further processing.

[0037] FIG. 5 is a flowchart of a process 200 for treating waste with a plasma arc carbonizer.
The process 200 starts by adjusting the parameters of the plasma arc carbonizer based on waste feed stock to be inputted (Step 202). Carbonizer parameters may illustratively include temperature, conveyor speed, dwell times, and atmosphere. In some inventive embodiments, once the carbonizer is at the required temperature, waste feedstock is loaded into the carbonizer (Step 204).
Subsequently, useable byproducts obtained from the carbonizer are collected, and non-useable outputs are either safely disposed of or reintroduced into the carbonizer (Step 206).

[0038] As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.

Claims (18)

1. A system for treating waste, the system comprising:
at least one plasma arc unit;
a carbonizer heated by said at least one plasma arc units and adapted to convert the waste to a useable product and resultant hot gases; and a thermal oxidizer in gaseous communication with said carbonizer to receive the resultant hot gases.

2. The system of claim 1 wherein the waste includes at least one of municipal solid waste, infectious medical waste, or bitumen that optionally contains non-reactive inorganics.

3. The system of claim 1 wherein said carbonizer employs anaerobic thermal conversion processing to treat the waste.

4. The system of any one of claims 1 to 3 wherein said carbonizer comprises a thermo-chemical reactor that is one of a drag-chain reactor, batch reactor, continuous-stirred-tank reactor, rotating drum, thermal oxidizers, or plug-in reactor.

5. The system of any one of claims 1 to 3 wherein said carbonizer operates under a reduced pressure of a partial or complete vacuum.

6. The system of any one of claims 1 to 3 wherein said at least one plasma unit operates with a nitrogen based atmosphere.

7. The system of any one of claims 1 to 3 wherein the useable products converted from the waste is one or more of carbon black, carbon-based inks and dyes, activated carbon, aerogels, bio-coke, bio-char, combustion feedstock to generate electricity, adjuncts for natural gas, aromatic oils, or phenols.

8. The system of claim 1 further comprising:
a sealed enclosure;
a piston driver for pushing one or more containers of waste into a plasma heating zone of said sealed enclosure.

9. The system of claim 8 further comprising:
an airlock in mechanical communication with the sealed enclosure, where the airlock introduces the one or more containers of waste into the sealed enclosure to prevent gases from escaping and to maintain the atmospheric conditions within the sealed enclosure.

10. The system of claim 8 further comprising:
a drop slot in said sealed enclosure;
a collection bin adapted to move remaining solids and carbon by-products that result from the treated waste with said piston driver to said drop slot for collection in the collection bin.

11. The system of claim 1 further comprising a controlled heated column adapted for refining and recovery of the resultant hot gases into distillates.

12. The system of claim 11 wherein the distillates comprise one or more of compounds of alkanes, alkenes, ethers, esters, phenols, aromatics, lignins, polycyclics; and substituted versions thereof where the substituent in place of a hydrogen atom is for example, a hydroxyl, an amine, a sulfonyl, a carboxyl, a halogen, or a combination thereof.

13. A method of using the system of claim 1 for treating waste with said plasma arc carbonizer, the method comprising:
adjusting a set of parameters of said carbonizer based on waste feed stock to be inputted;
loading waste feedstock into said carbonizer; and collecting useable byproducts obtained from the carbonizer.

14. The method of claim 13 wherein the adjustable set of parameters for said carbonizer include one or more of temperature, conveyor speed, dwell times, or atmosphere.

15. The method of claim 13 further comprising safely disposing of non-useable outputs from said carbonizer or reintroducing the non-useable outputs into said carbonizer.

16. The method of claim 13 further comprising supplying the resultant hot gases to a controlled heated column for distilling and refining and recovery into distillates.

17. The method of claim 16 wherein the distillates include one or more of compounds of alkanes, alkenes, ethers, esters, phenols, aromatics, lignins, polycyclics; or substituted versions thereof where the substituent in place of a hydrogen atom is a hydroxyl, an amine, a sulfonyl, a carboxyl, a halogen, or a combination thereof.

18. The method of claim 16 wherein any hot gases or solids that do not distill out as a useable by-product are either to be further scrubbed and safely disposed of, or recirculated into the carbonizer for reprocessing.