Pyrolysis reactor with optimized reaction sequencing

Abstract

System and method for processing pyrolyzable materials in order to recover usable end products are disclosed. The pyrolysis process comprises a number of stages. First pre-treating is to reduce moisture content to approximately 15%. Second is to optimize the volatile organic under the heat and vacuum. This treatment stage is carried out at the temperature between 350 to 400 C. Next, the material is treated with heat and vacuum to produce hot gas and solid carbon residue. This stage is carried out at the temperature up to 800 C. The solid carbon residue can be separated from the hot gas, the volatile organic materials condensed to produce liquid hydrocarbon and gas products. Pyrolysis processes and system according to the present invention are able to thermally decompose carbon-containing materials, including, but not limited to, tires and other rubber-containing materials, hydrocarbon-containing products including pyrolysis oil, used oil and lubricants, organic wastes and alike, carbon containing minerals like brown and bituminous coal, oil shale and oil bearing schists. System and pyrolysis methods according to aspects of the present invention may be successful on a commercial scale.

Claims

1. A pyrolysis reactor for processing pyrolyzable materials in order to recover usable end products comprising: (a) a substantially cylindrical retort, extending through and stationary relative to said reactor and having an upstream end and a downstream end, each end being outside of said reactor; (b) feeding means for feeding the substance containing pyrolyzable materials into said retort, said feeding means communicating with the upstream portion of said retort; (c) means located within said retort for moving the pyrolyzable materials from the upstream portion of said retort to the downstream portion thereof; (d) solids residue removing means for removing solids residue from said retort, said solids residue removing means communicating with the downstream portion of said retort; (e) solids residue introducing means for introducing said solids residue removed from said retort, one end of said introducing means communicating with said solids residue removing means and the other end thereof communicating with the bottom portion of said retort; (f) solids residue extracting means for extracting solids residue from said retort and communicating with the lower downstream portion of said retort; (g) heating means for heating the particles; (h) usable end products means condensable hydrocarbon vapors and product gas (i) hydrocarbon vapors removing means for removing hydrocarbon vapors from said retort, said hydrocarbon vapors removing means communicating with said retort at least one point located upstream, with respect to the flow of said pyrolyzable materials in said retort, from said feeding means; (j) solids residue flow controlling means for controlling the flow of the solids residue while the solids residue is being employed as particles of the said retort such that the solids residue flow from the upstream portion to the downstream portion of said retort and in a direction substantially countercurrent to the flow within said retort of the pyrolyzable materials, said solids residue flow controlling means including at least one partition separating said retort into a plurality of successively adjacent sections, each partition which is downstream, with respect to the flow of particles in said retort; and (l) regulating means for regulating the levels of the pyrolyzable materials maintained within the said retort whereby solids residue which is in a section of said retort downstream, with respect to the flow of particles in said retort, from another section thereof may be caused to overflow into the section of the retort which is immediately downstream therefrom with respect to the flow of particles in said retort.

2. A system according to claim 1 further including: (a) heating means to heat the granular material; and (b) heating means coupled in gas flow communication with said heating means to pyrolyze said granulated material and to produce hot gases which are transferred from said heating means; (c) classifier means coupled to receive granular material; (d) transfer means coupled to said classifier means to convey the receive granular material to said heating means.

3. A system to heat granular material and to pyrolyze comprising: (a) multiple hearth heating means including, i. an upper zone to heat the granular material; ii. a lower zone to receive hot granular material and to pyrolyze said material; (b) classifier means coupled to receive granular material from said multiple hearth heating means; (c) transfer means coupled to said classifier means to convey the granular material to said lower zone means.

4. A system according to claim 3 further including means to convey the hot granular material directly from said upper zone to said lower zone.

5. A process for pyrolyze granular material comprising: (a) introducing the granular material into a heating means; (b) heating the granular material to produce hot gases; (c) transferring the hot gases from the heating means to heat the granular material; (d) transferring the hot granular material to a classifier; (e) transferring the granular material from the classifier to the heating means to be heated.

5. The system claimed in claim 1 wherein the hydrocarbon vapors removing means communicate with said retort at a plurality of points located substantially along the said retort and downstream, with respect to the flow of said granular material in said retort, from said feeding means.

6. The system claimed in claim 3 wherein: (a) the substance within the multiple hearth heating means of the said retort is heated to a temperature approximately 400 C. or 725 F., (b) the substance within the middle section of the said retort is heated to a temperature approximately 900 C. or 1652 F., (c) and the temperature of the section nearest the downstream end of the said retort maintained at approximately 149 C. or 300 F.

7. The system claimed in claim 3 wherein the length of time between when the said granular material is fed into the retort and when corresponding solids residue is removed from the retort is approximately: (a) 5 to approximately 15 minutes for the said upper zone of said retort; and (b) 45 to approximately 55 minutes for the said lower zone of said retort.

8. The system claimed in claim 3 wherein the removal of the hydrocarbon vapors is performed by removing the hydrocarbon vapors at a plurality of points located substantially along the said retort.

9. The system claimed in claim 1, wherein the thermal coating of the said reactor the inner metal bond coating layer, which contacts the surface of the said reactor, consists essentially of enamel frit, sand mixed with 50% solution of sodium tetra-Borat (Na.sub.2B.sub.4O.sub.7), clay, titanium dioxide, and colloidal silicon dioxide (SiO.sub.2). The metal bond coating layer is, in turn, coated with an outer layer containing fluoroplastic F4D and oxiethylated alkylphenols (polyethylene-ethylene-alkyl phenyl ethers) (RC.sub.6H.sub.4O(CH.sub.2CH.sub.2O).sub.nH or Neonol AF 9-12 oxyethylated nonylphenol (C.sub.9H.sub.19C.sub.6H.sub.4O(C.sub.2H.sub.4O).sub.12H).

10. The system claimed in claim 1, wherein the anti-adhesive coating system of the said reactor the inner metal bond coating layer, which contacts the surface of the exhaust system, consists essentially of perfluoropolyetheric acid 6MFK-180 (CF.sub.3O(CF.sub.2CF.sub.2O)nCF.sub.2COOH where n=34-35) mixed with 1,2-difluorotetracloroethane (C.sub.2Cl.sub.4F.sub.2) and 1,1,2-trifluorotrichlorethane (CF.sub.2ClCFCl.sub.2) at the 4:1 weight ratio.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects and advantages and novel features of the present invention will become apparent from the following detailed description of the preferred embodiment of the invention illustrated in the accompanying drawings, wherein:

[0024] FIG. 1 is a vertical view of the pyrolysis reactor of the invention;

[0025] FIG. 2a is a vertical view taken along the FIG. 1 and with portions shown the upper level of the pyrolysis of the invention in schematic;

[0026] FIG. 2b is a vertical view taken along the FIG. 1 and with portions shown the upper level of the pyrolysis of the invention in transparent schematic;

[0027] FIG. 2c is an enlarged fragmented sectional view of the bolted flange connection;

[0028] FIG. 3a is a vertical view taken along the FIG. 1 and with portions shown the middle level of the pyrolysis of the invention in schematic;

[0029] FIG. 3b is a vertical view taken along the FIG. 1 and with portions shown the middle level of the pyrolysis of the invention in transparent schematic;

[0030] FIG. 3c is a view taken from the FIG. 1 and with portions shown the upper view of the middle level of the pyrolysis of the invention in transparent schematic;

[0031] FIG. 3d is a view taken from the FIG. 1 and with portions shown the upper view of the middle level heating elements;

[0032] FIG. 4a is a vertical view taken along the FIG. 1 and with portions shown the lower level of the pyrolysis of the invention in schematic;

[0033] FIG. 4b is a vertical view taken along the FIG. 1 and with portions shown the lower level of the pyrolysis of the invention in transparent schematic;

[0034] FIG. 4c is a view taken from the FIG. 1 and with portions shown the upper view of the lower level of the pyrolysis of the invention in transparent schematic;

[0035] FIG. 4d is a view taken from the FIG. 1 and with portions shown the side view of the lower level of the pyrolysis of the invention in transparent schematic.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Specific details of several embodiments of the technology are described below with reference to FIGS. 1-4. Other details describing well-known structures and systems often associated with pyrolysis reactors have not been set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Many of the details, dimensions, angles, and other features shown in the Figures are merely illustrative of particular embodiments of the technology. Accordingly, other embodiments can have other details, dimensions, angles, and features without departing from the spirit or scope of the present technology. A person of ordinary skill in the art, therefore, will accordingly understand that the technology may have other embodiments with additional elements, or the technology may have other embodiments without several of the features shown and described below with reference to FIGS. 1-4.

[0037] For the purpose of this description the pyrolysis reactor 1 should be understood to include an upper zone (FIGS. 2a and 2b) wherein pyrolyzable materials is heated to a temperature approximately 400 C. or 725 F., a middle zone (FIGS. 3a, 3b, 3c and 3d) wherein dry pyrolyzable materials is heated to a temperature approximately 900 C. or 1652 F., and a lower zone (FIGS. 4a, 4b and 4c) wherein the ash is removed. Multiple temperature sensing means (not shown) are disposed within the divided chambers (sections) of the pyrolysis reactor in order to monitor as well as control the continuous pyrolysis operation.

[0038] FIG. 1 shows a diagram of one embodiment of the apparatus of the present invention. Pyrolyzable materials, in the form of sorted municipal wastes, used tires, used plastic and plastic wastes; bituminous coal or other wood residue is initially stored dried to approximate humidity level of 18% in a feedstock preparation section (not shown). The pyrolyzable materials are grinded to the grain size of approximately 5 mm in a grinder (not shown). As shown in FIG. 1, process material is loaded into a hopper 2. The hopper 2 has a closing lid or similar arrangement for limiting free admission of air, particularly if air contamination may be a concern, and then is directed, by suitable means, such as a conveyor 3 or a vacuum system (not shown) from feedstock preparation section into an inlet of the input end of a pyrolysis reactor vessel 1, which is shown in more detail in FIG. 2a. An outlet is provided at the exit end of the reactor vessel 1 to remove ash residue. This product is the result of the thermo-chemical processes occurring within the pyrolysis reactor, which will be explained in more detail hereinafter.

[0039] The reactor vessel 1 in the embodiment shown in FIG. 1 is an elongated cylindrical tube, approximately 1600 mm or 63 inches in diameter and 7000 mm or 24 feet long. The reactor vessel comprised generally of a cylindrical steel vessel sections having a removable top head 7, each section with cooperating bolted flanges 12 that can be bolted tightly together by a plurality of studs and nuts (FIG. 2c). The reactor vessel comprises an inert oxidation-resistant metal, such as steel 310S AISI, or titanium clad steel. In the embodiment shown, the walls of the reactor vessel 1 are 0.060 inches thick, although this dimension is not critical and can be varied substantially. Pyrolysis reactor 1 is inserted into a protective cylindrical shell and insulated by a thermal resistant material (not shown) such as ceramic fiber blankets (2600 degree Fahrenheit operating temperature) or pyrolytic graphite.

[0040] In the embodiment shown in FIG. 2a, inlet 5 is an opening having a circular or oval configuration. The diameter of the circular opening is approximately 7 inches, with the dimensions of the oval opening being commensurate. A vertical cylindrical steel protective shell 9 supported on a plurality of structural steel columns (not shown). Protective cylindrical shell 9 comprises an oxidation-resistant metal, such a steel type 304. A center shaft 6 is disposed in the centre of the upper section of the pyrolysis reactor. A removable top head 7 of the pyrolysis reactor is to prevent outside oxygen contained air mix with the granulated material undergoing first stage thermal conversion. The pyrolysis reactor 1 conventionally is equipped with a plurality of shell mounted burners 8. The burners 8 are fired utilizing either natural gas or a liquid fuel to provide the process heat required for the specific application. The burners 8 usually are equipped with gas pilots to ensure continuity of the combustion process and the burners 8 fire horizontally and quasi tangentially into the space available between the hearths 14. The gas burners 8 being employed operates either with a normal or full burner fuel supply or with a diminished or fuel-starved fuel supply during the pyrolysis cycle in a controlled manner. Exhaust gases are exiting from the burners 8 through the exhaust system 11. Exhaust valve 10 is to regulate the gas flow.

[0041] The presently preferred embodiment shown in FIG. 2b includes a conventional multiple hearth heaters 14. A plurality of hearths 14 are located within the vessel perpendicular to its axis, and spaced in the order of two (2) to five (5) feet or more depending on the application of the reactor 1. The number of hearths 14 varies and typically has ranged from a minimum of four to a maximum of seventeen. A center shaft 6 is supported by a plurality of support arms 13 parallel to the hearths 14. The double-wall air-cooled cast nodular iron or alloy center shaft 6 is mounted to rotate slowly about its vertical axis. The shaft 6 carries a number of attached rabble arms, each equipped with a set of removable alloy rabble teeth or plows. Drive means (not shown) is coupled to the upper end of the center shaft 6 to cause the center shaft to rotate so that the rabble arms urge material to travel across the hearths 14. The hearths 14 are constructed so that material flows downward through the furnace in a generally serpentine path.

[0042] Referring to FIG. 3, the present invention includes a cylindrical heater body having a recessed upper surface defining a heater chambers. The heater body 1 is fitted into a corresponding circular opening of a protective cylindrical shell. The heater chambers are substantially cylindrical chambers that are lined with insulators. The insulators are ceramic fiber blankets (2600 degree Fahrenheit operating temperature) or pyrolytic graphite. Pyrolytic graphite is an anisotropic material that conducts heat well in one direction and poorly in the transverse direction. It is installed or oriented into the heater chambers so that it conducts heat well in the direction parallel to the inner surfaces of the heater chamber and poorly in the perpendicular direction. This confines the heat within the heater chambers minimizing losses to the surrounding reactor walls, and helps ensure that the heating within the chambers are uniform.

[0043] FIG. 3a demonstrates outer arrangements of burners 8, heat conducting elements 15 and exhaust system 11, while FIGS. 3b-3d are to demonstrate internal arrangement of the heating schema. The illustrated heaters arrangement forms the overall heater unit for the middle section of the pyrolysis reactor. Such arrangement allows each heating element to be controlled separately with minimal effect on adjacent heaters. This arrangement allows each heating element (or group of elements) to be controlled separately to provide applied heat to maintain the desired axially constant reactor wall temperature. The heater control can be controlled to be responsive to the measured temperature for each reactor length segment. The improved heating method for the pyrolysis reactor can be practiced for any practical reactor size. Generally, it is expected that the operation could be low pressure due to the high operating temperatures. Utilization of the improved heating method would allow maximum reactor throughput at any size. Char/ash resulting from pyrolyzing the carbon contained in pyrolysis reactor 1 is easy to blend, easy to analyze, and easy to store. Pyrolysis reactor 1 also allows the char/ash to become a raw material rather than just a carbon enriched compounds. FIGS. 4a-4d are to demonstrate pyrolysis reactor 1 unloading schematic. During the continuous operation of the pyrolysis reactor, char/ash is being divided to four equal streams to be removed by unloading mechanism 18 (FIG. 4a). Bottom section of the reactor 1 as shown in FIG. 4a comprised of 4 unloading shafts 17, means to remove pyrolysis gases 16 and exhaust gases removing system 11. In addition, presently preferred embodiment shown a system to introduce argon-hydrogen mix (at the volume ratio of 75:15) or air-water stem mix ((at the volume ratio of 1:1) 19. FIGS. 4b-4c is to demonstrate detailed unloading schematics. FIGS. 4c-4d is to demonstrate unloading mechanism in more details. As can be seen from FIG. 4d, the waste-feeding screws are connected to air sealed chamber 20, which is in turn, is connected to char/ash de-activation and cooling system 22. The inner surface of the pyrolysis reactor 1 according to this invention may be coated with a film in any manner provided that a uniform film of a anti adhesive substance is formed on the desired surface portions of the pyrolysis reactor, the inner wall of the retort, the hearth outer surface, middle section of the reactor, unloading mechanism and/or the air vent portion. At the present time, however, there is practically no process available whereby an anti-adhesive film of sufficiently high wear resistant properties can be formed at a speed of commercial significance over an adequately large surface area. For this reason it is recommended to use the process now to be described.

[0044] Formation of the Composite Coating for Steel

[0045] One of the tasks of the present invention is creation of the silicate basis anti adhesive protective coating with the self-sedimentation of fluoride suspension deposition on the substrate surface. The problem is solved by the introducing two layers of coating comprised of: the first layerenamel frit (B.sub.2O.sub.340.6-42.0; CoO0.3-0.7; Na.sub.2O6.0-6.5; CaO6.0-6.5; Al.sub.2O.sub.316.0-16.8; TiO.sub.223.2-24.0; Li.sub.2O0.3-0.7; SiO.sub.25.0-6.0 of mass %), sand, clay, titanium dioxide, mix of sodium tetra-Borat (Na.sub.2B.sub.4O.sub.7) and colloidal silicon dioxide (SiO.sub.2) at the weight ratio of 1:1; the second layerfluoroplastic F4D and oxiethylated alkylphenols (polyethylene-ethylene-alkyl phenyl ethers) (RC.sub.6H.sub.4O(CH.sub.2CH.sub.2O).sub.nH or Neonol AF 9-12 oxyethylated nonylphenol (C.sub.9H.sub.19C.sub.6H.sub.4O(C.sub.2H.sub.4O).sub.12H);

[0046] In order to prepare the first layer of the protective coating the following ratio of components (Mas. %) have been used: The first silicate layer ESP-200 enamel Frit56.75-70.67 Sand14.13-22.70 Clay4.24-5.68 titanium dioxide0.07-0.28 50% mix of sodium tetr-borate ad colloidal silicone0.28-0.34; Second fluoroplastic layer consist of: fluoroplastic F4D brand37.40-42.20,

[0047] The F4MD brand9.35-12.05, oxiethylated alkylphenols 3.61-6.54, distilled waterthe rest.

[0048] This silicate layer (0.15-0.30 mm thick) was applied on the grounded surface with method of a regional pouring, then was dried up and heated at a temperature of 79010 C., at the heating increase ratio of 50 C. per hour. Then fluoroplastic suspension was applied and dried at the temperature of 350 C. for at least 3 hours. The silicate and fluoroplastic coating has high operational properties (anti-adhesion and wear resistance). As a result, of the pyrolysis, the treated product is decomposed into a solid phase (a mixture of carbon residue that contains coke and tar, and a gaseous phase (pyrolysis gas). A part of the pyrolysis gas developed in the pyrolysis reactor is sent to the waste drier and/or to the burners 8 of the reactor for use as an additional heat carrier.

[0049] Thus it has been shown that the invention provides a novel reactor for pyrolytic processing and more efficient utilization of carbon contained wastes as compared to conventional reactors of this type. The aforementioned reactor is simple in construction, provides efficiency in the pyrolysis reaction, sufficient compaction of the waste material for displacement of air from the material being treated, efficient mixing of the material being treated, and efficient loading, unloading of the material into and from the reactor along with efficient conveyance of the material through the reactor. The structure of the reactor is characterized by a low metal-to-power ratio and hence by low manufacturing cost.

[0050] Although the invention has been shown and described with reference to specific embodiments, it is understood that these embodiments should not be construed as limiting the areas of application of the invention and that any changes and modifications are possible provided that these changes and modifications do not depart from the scope of the attached patent claims. For example, the retort and the external casing that surrounds the retort may have shapes different from those shown in the drawings and can be made from different heat-resistant materials. The loading and unloading mechanisms of the pyrolysis reactor may have structures different from those shown in FIG. 1 and FIG. 4. For example, an electric drive can be used for opening and closing the sliding gates. The sliding gates may be replaced by rotating gates pivotally installed on the inner walls of the loading hopper. The reactor sections can be assembled by inserting the male projections of one of the sections into female bores of the adjacent section.

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