Self-sustaining continuous pyrolysis reactor for wood-resin composites and method for operating same

Abstract

The present invention relates to a self-sustaining pyrolysis reactor and a method for operating same, wherein the reactor is designed so that it can carry out the pyrolysis of wood-resin composite materials, such as MDF, MDP and plywood of all types, wherein the reactor uses an external heat source merely to start the pyrolysis process, and generates, at the end of its operation, not only charcoal but also high added value products, such as nitrogen salts, and wherein the reactor can be used in the field of mechanical engineering and biotechnology, as it relates to a plant biomass conversion method.

Description

[0001] CONTINUOUS PYROLYTIC REACTOR OF RESIN WOOD COMPOSITES WITH FEEDBACK AND METHOD FOR OPERATION OF THE SAME

[0002] FIELD OF APPLICATION

[0003]

[0001] This present invention patent application concerns a feedback pyrolysis reactor and a method of operation for the same, with this reactor constructed in such a way that it can carry out the pyrolysis of resin composite wood materials, such as MDF, MDP and plywood of all types, and with this reactor using an external heat source only to start the pyrolysis process, and generating at the end of its operation not only charcoal but also high added value products such as nitrogen salts, with this reactor having its application in the field of mechanics and biotechnology as it is a process of converting plant biomass.

[0004] FUNDAMENTALS AND ADVANTAGES OF THE INVENTION AND STATE OF THE TECHNIQUE

[0005]

[0002] The pyrolysis process is already widely described and well-known, with the word pyrolysis meaning "decomposition by heat," that is, the degradation of a material by thermal energy. Pyrolysis reactors work as follows: organic material, whether vegetable material like wood or another type of material, such as plastic, enters a chamber where it is heated by an external heat source. This heat can be obtained in various ways, such as by burning natural gas without the presence of oxygen. As the temperature of this chamber increases, the organic material decomposes into a gaseous fraction that we can call biogas or synthesis gas, and a solid carbon-based organic residue (charcoal) that remains inside the reactor and is later removed in the form of charcoal. In high-temperature reactors, the residue is composed primarily of the ash of the initial material.

[0006]

[0003] There are some types of pyrolytic reactors already known in the state of the art. Three of these reactors are the high-temperature pyrolytic reactor, the low-temperature pyrolytic reactor, and the simple conventional carbonization reactor.

[0004] In the high-temperature pyrolytic reactor, the reactor is heated by a heat source, this heat being generated via electrical energy or through the combustion of gas, oil, biomass, among other fuels, leading to the formation of biogas, bio-oil, and ash when the reactor operates at temperatures above 900°C, or biogas, bio-oil, and coal when this reactor operates at temperatures below 900°C.

[0007]

[0005] In the low temperature pyrolytic reactor, the heat source is microwaves, and charcoal can be produced, as the reactor temperature is controlled and other derivatives are also obtained as in high temperature pyrolytic reactors, such as biogas and bio-oil.

[0008]

[0006] In the conventional carbonization reactor, the heat source is the burning of the wood itself, with a control of the oxygen input into the furnace leading to the carbonization of the wood, producing only charcoal, and it is not possible to recover biogas and bio-oil, as in previous methods. This reactor, however, does not require an external heat source to operate.

[0009]

[0007] For the production of charcoal, one of these methods is via the use of a raw material that enters combustion in a relatively easy and sustained way, such as firewood in a conventional carbonization reactor, where the initial burning of the wood is used as a heat source so that the carbonization reaction can occur, however, this process requires pre-selected and high-cost raw material, as this raw material must be dry or with low humidity.

[0010]

[0008] In the case of raw materials with high humidity or that do not combust at low temperatures, pyrolytic reactors with an external energy source are used, such as high-temperature pyrolytic reactors or low-temperature pyrolytic reactors. This type of reactor uses low-cost raw materials, but uses fuel throughout the material processing, which increases the cost of the process.

[0011]

[0009] The pyrolytic reactor described in this patent application, the Clearchar feedback pyrolytic reactor, uses resin-bonded composite woods, such as MDF, MDP and plywood of all types, as raw material. Resin-bonded composite woods are materials manufactured from wood fibers or fractions.

[0012]

[0010] The acronym MDF stands for Medium Density Fiberboard. It is a reconstituted wood panel, produced by bonding wood fibers with synthetic resins and additives. The wood panels are glued together with resin and fixed with pressure.

[0013]

[0011] The acronym MDP stands for Medium Density Particleboard, and this is a particleboard panel made up of wood particles bonded together - mainly with urea resins - through the action of temperature and high pressure.

[0014]

[0012] Laminated plywood is made from thin sheets of pressed wood, usually in an odd number, glued together with adhesive, with a dyed cover and pine core. The product is made with urea-formaldehyde-based glue and is best suited for construction, packaging, pallet racking, etc.

[0015]

[0013] According to ABNT standard NBR 10.004 / 2004, which addresses the definition and classification of solid waste, MDF is classified as Class I - Hazardous. It may contain synthetic resins and, in addition, the material may be treated with halogenated products, antifungals, paints, varnishes, adhesives, and coated with plastics and PVC, which makes it unfeasible for use as fuel under any combustion conditions. This class includes waste with characteristics of flammability, corrosivity, reactivity, toxicity, and pathogenicity, for example: paint residues, used oils, solvents, rags, cloths, and paper contaminated with oils and greases, and MDF waste.

[0016]

[0014] Because this type of waste poses a risk to the environment and society, it requires special disposal, which increases the cost of the product. Because of this, many establishments have been disposing of this waste incorrectly, such as inert construction material or household waste, in landfills. When disposed of in the soil, MDF dust and shavings can be a source of contamination, also reducing the landfill's capacity and useful life.

[0015] This leads to a large availability of material on the market and a lack of a viable way to utilize it.The Clearchar reactor was developed as a modified pyrolysis reactor to efficiently process resin-treated composite wood. The Clearchar reactor uses as an energy source the gas generated by heating these woods during the pyrolysis process. This gas is a result of the decomposition of the resin that constitutes these woods. This also makes this type of material flame-retardant. When exposed to a heat source or flame, the resin decomposition prevents the propagation, extinguishing the flame and preventing the wood from burning sustainably. This same flame-retardant process is present in products such as electrical cables, which, despite being coated in plastic, do not ignite when exposed to heat like ordinary plastic. This also occurs in many other materials such as foams and treated fabrics.

[0017]

[0016] Due to this characteristic of not propagating flame, the conventional carbonization reactor cannot be used in the conversion of resin-containing composite wood into charcoal, as the resins prevent the burning of resin-containing composite wood in a sustained manner, which is essential for the functionality of this type of process.

[0018]

[0017] High and low temperature pyrolysis reactors can convert resin-bonded composite wood into charcoal, but to do so they require an external heat source to keep the process active, which makes this process inefficient from an energy point of view since a lot of energy is spent to convert resin-bonded composite wood into charcoal, not being a viable option for treating this material.

[0019]

[0018] However, the Clearchar pyrolysis reactor described in this patent application uses an external heat source only to start the pyrolysis process, and when the reactor's working temperature is reached, the gases generated by heating the resin-treated composite wood are burned in the reactor's combustion chamber, feeding back into the pyrosis process, and from that moment on, the process becomes self-sustaining, not needing an external fuel source, and because it is a continuous-working reactor, as long as raw material is being fed, the process will operate autonomously.

[0020]

[0019] Regarding prior art documents, one document found is BG112015, entitled “METHOD AND EQUIPMENT FOR ROTARY PYROLYSIS” and published on 11 / 30 / 2016, with a summary translated and reproduced below: “The present invention relates to a method and equipment for rotary pyrolysis, the use of which is found in the combustion of residual biomass. With the rotary pyrolysis method, the necessary heat is created by burning externally generated hydrogen through the electrolysis of water. High temperatures are generated without creating nitrogen oxides. In this method, pyrolysis is achieved in a rotating and vibrating pseudo-boiling bed, both stationary and mobile. The mechanism includes a vertically positioned rotary pyrolysis reactor, equipped with a tangentially positioned power device, a mechanism located at the bottom of the reactor for removing hard solids, and a recirculation loop located on the side of the reactor body.The body consists of a cone-shaped base and a cylindrical part, as the power device is placed in the middle of this cylindrical part. On both sides of the power device, holes are drilled vertically, one below the other, from top to bottom, into which are placed an upper and a lower steam nozzle. Below which, in openings in the molded cone-shaped base, hydrogen torches are mounted. Steam ejectors are mounted between the hydrogen torches and the lower steam nozzles.

[0021] GENERAL DESCRIPTION OF THE INVENTION

[0022]

[0020] A feedback pyrolysis reactor and a method of operation for it, with this reactor constructed so that it can perform the pyrolysis of resin-bonded composite wood materials, such as MDF, MDP and plywood of all types, and with this reactor using an external heat source only to start the pyrolysis process, and generating at the end of its operation not only charcoal but also high value-added products such as nitrogen salts, with this reactor having its application in the field of mechanics and biotechnology because it is a process of converting plant biomass

[0023] DESCRIPTION OF FIGURES

[0024]

[0021] The invention will be described in detail below, and for better understanding, references will be made to the attached drawing, which represents:

[0022] Figure 1: Diagram showing the reactor and its constituent elements.

[0025] DETAILED DESCRIPTION OF THE INVENTION

[0026]

[0023] THE CONTINUOUS FEEDBACK PYROLYTIC REACTOR OF RESIN WOOD COMPOSITES AND METHOD FOR OPERATION THEREOF describes a feedback pyrolysis reactor (1), which we name Clearchar reactor, its functionality being the production of charcoal from resin composite woods such as MDF, and a method for the operation of this reactor. In this reactor, the pyrolysis gas is burned in a combustion chamber (4) in a controlled manner, to ensure the adequate burning of the pyrolysis gas, leading to low pollutant gas emissions since gases are burned continuously and always at a temperature above 600° C.

[0027]

[0024] This reactor (1) has as its main feature the use of the gas generated in the pyrolysis process as a heat source so that the process operates continuously. By operating at a temperature in the range of 600° C, the conversion of wood into charcoal is optimized, thus minimizing the formation of ash and excessive burning of the wood, prioritizing the conversion of wood into charcoal. Another feature of this reactor (1) is the recovery of nitrogenous compounds generated by the degradation of the resin, in the form of nitrogen salts.Due to the burning of nitrogen-rich pyrolysis gas in a combustion chamber (4) isolated from the pyrolysis chamber (2), and with controlled temperature, we are able to adjust the combustion of the pyrolysis gas efficiently, generating a low residual particulate matter in the exhaust gases and a high conversion rate of nitrogen oxide gases into nitrogen salts in the gas scrubber, avoiding the release of harmful greenhouse gases such as nitrogen oxides, carbon monoxide, methane, among others, which would be released with the pyrolysis of MDF in conventional pyrolysis reactors.

[0028]

[0025] Regarding the physical construction of the reactor (1), it has a pyrolysis chamber (2) in which the wood compound is placed via an inlet (3), with this chamber (2) being connected via a small interconnection (5) with a combustion chamber (4), and with this combustion chamber (4) heated through an opening in its base by a gas heater (6), carrying out the transfer of gases between this combustion chamber (4) and the pyrolysis chamber (2). The dimensioning of the interconnection (5) is such as to make the connection between the pyrolysis (2) and combustion (4) chambers almost non-existent, in order to optimize the pyrolysis process and maintain this interconnection (5) with a temperature close to the temperature of the combustion chamber (4). The reactor has a flow chimney (7) coupled to the combustion chamber (4), with this chimney (7) located after the inlet (3) to prevent heating of the wood outside the pyrolysis chamber (2).A material conveying screw (8) is located internally in the pyrolysis chamber (2), with this screw (8) having the ability to rotate, with this rotation being used during the pyrolysis process to assist it during this by transporting the material undergoing pyrolysis from the inlet (3) of the reactor (1) to a gate valve (9), with this gate valve (9) being coupled to the pyrolysis chamber (2) and which assists the exit of the material after the material moved by the screw (8) reaches this valve (9) and has undergone the pyrolysis process. The gate valve (9) and the inlet (3) are located at opposite ends of the reactor to enable the movement of the material through the screw (8) throughout the pyrolysis chamber (2).

[0029]

[0026] A common problem in pyrolysis reactors is the obstruction of the pyrolysis gas pipes and the system in general, due to the formation of tar and carbon deposits in the pyrolysis gas pipes. In the Clearchar reactor (1) this problem does not exist, since the connection (5) between the pyrolysis chamber (2) and the combustion chamber (4) is almost non-existent and as this interconnection (5) is always maintained at a temperature close to the combustion chamber (4), there is thus no formation of tar or carbon deposits, increasing the efficiency of the process and achieving a significant reduction in operating costs.

[0030]

[0027] Another important factor is that the Clearchar reactor (1) does not require the pyrolysis gas washing step, and no liquid effluents are generated during the operation of the Clearchar reactor (1), whereas conventional pyrolysis reactors generate liquid effluents in the form of bio-oil mixed with gas washing water.

[0031]

[0028] By not burning pyrolysis gases, conventional reactors generate highly polluting gases, such as carbon monoxide and VOCs, or volatile organic compounds, and in the Clearchar reactor (1) the pyrolysis gases are burned efficiently and the nitrogen compounds from the burning of resin composite woods are concentrated through the degradation of the resin, generating a byproduct of the process with high added value, in the form of nitrogen salts.

[0032]

[0029] The method for operating this pyrolysis reactor (1) now follows:

[0033] • First Stage - The inlet (3) is loaded with resin-treated composite wood material that will undergo pyrolysis and the internal conveyor screw (8) must be switched off and without material, and the reactor (1) is then heated using the gas heater (6) until the temperature of the pyrolysis chamber (2) reaches 400 °C;

[0034] • Second Stage - Once the temperature of 400°C is reached in the pyrolysis chamber (2), the gate valve (9) at the outlet of the final material obtained is activated and the screw (8) is activated at a speed of 4 RPM with the gas burner (6) on;

[0035] • Third Stage - The screw (8) is loaded with resin-bonded composite wood material and the pyrolysis reaction begins, with the pyrolysis gases beginning to burn in the combustion chamber (4), slowly raising the temperature of the pyrolysis chamber (2);

[0036] • Fourth Stage - When the temperature of the pyrolysis chamber (2) reaches 500°C, the gas burner (6) is turned off and from that moment on the reactor (1) works in a self-sustaining manner; • Fifth Stage - The rotation speed of the conveyor screw (8) is gradually increased to a speed of 25 RPM, and the temperature of the pyrolysis chamber (2) is observed in order to maintain its temperature between 450 and 550°C;

[0037] • Sixth Stage - Once the working temperature and transport speed have been reached via the ideal rotation of the screw (8) of 25 RPM, it is only necessary to keep the inlet (3) loaded and the reactor (1) then works continuously, thus producing charcoal, and this charcoal being ejected from the pyrolysis chamber through the gate valve (9);

[0038] • Seventh Stage - To turn off the reactor (1), let the screw (8) transport the resin-treated composite wood material from the inlet (3) and as the material inside the pyrolysis chamber (2) runs out, the temperature of this chamber (2) drops and the reactor turns off (1) automatically.

Claims

METHOD, consisting of a reactor (1) having a material inlet (3), a pyrolysis chamber (2), a combustion chamber (4) with an opening at its base to which a gas heater (6) is coupled, a chimney (7) coupled to the combustion chamber (4) and a gate valve (9); the pyrolysis (2) and combustion (4) chambers are connected via an interconnection (5); the reactor (1) has a material conveyor screw (8) located internally in the pyrolysis chamber (2); the chimney is placed after the inlet (3), going towards the load movement; so that the gate valve (9) and the inlet (3) are located at opposite ends of the reactor (1); the reactor (1) characterized by having seven operating stages: - in the first stage, the reactor inlet (3) is loaded with resin-coated composite wood material and the internal conveyor screw (8) must be switched off and without material, and the reactor (1) is heated using the gas heater (6) until the temperature of the pyrolysis chamber (2) reaches 400 °C; - in the second stage, when the temperature of 400°C is reached in the pyrolysis chamber (2), the gate valve (9) is activated and the screw (8) is activated at a speed of 4 RPM with the gas heater (6) on; - in the third stage, the screw (8) is loaded with resinous composite wood material and the pyrolysis reaction begins, with the pyrolysis gases beginning to burn in the combustion chamber (4), slowly raising the temperature of the pyrolysis chamber (2); - in the fourth stage, when the temperature of the pyrolysis chamber (2) reaches 500°C, the gas heater (6) is turned off, then the gases generated by heating the resin composite woods are burned in the combustion chamber (4) of the reactor (1); - in the fifth stage, the rotation speed of the conveyor screw (8) is increased to a speed of 25 RPM, and the temperature of the pyrolysis chamber (2) is observed in order to maintain its temperature between 450 and 550 °C; - in the sixth stage, when the working temperature and transport speed are reached via the ideal rotation of the screw (8) of 25 RPM, the input (3) of resinous composite wood material is maintained and the reactor (1) then operates continuously, with charcoal then being produced and ejected from the pyrolysis chamber through the gate valve (9); - in the seventh stage, to turn off the reactor (1), the screw (8) is allowed to transport the resin composite wood material from the inlet (3) and as the material inside the pyrolysis chamber (2) runs out, the temperature of this chamber (2) drops and the reactor turns off (1) automatically. 2) METHOD, according to claim 1, characterized by carrying out the pyrolysis of resin-containing composite woods and, through the degradation of these resins existing in these woods via the pyrolysis process and subsequent concentration of nitrogen compounds, obtaining nitrogen salts as the final result. I declare for all due purposes that, in order to provide better understanding, I have rewritten the set of claims, joining claims 1 and 2 and, thus, moving the characterizing part, in addition to changing the numbering of claim 3 to 2, without, however, departing from and / or altering the inventive concept of the patent. The amendments do not add new material.

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