Information
-
Patent Grant
-
6638396
-
Patent Number
6,638,396
-
Date Filed
Monday, November 4, 200222 years ago
-
Date Issued
Tuesday, October 28, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Lazarus; Ira S.
- Rinehart; K. B.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 201 7
- 201 8
- 201 13
- 201 32
- 202 100
- 202 133
- 202 136
- 202 137
- 202 216
- 110 342
- 110 345
- 110 218
- 110 219
- 110 224
- 110 226
- 110 229
- 110 232
- 110 233
- 110 303
-
International Classifications
-
Abstract
A method and apparatus for processing a waste product and producing a synthesis gas is provided. The system includes a sealed, heated rotatable drum for preheating and preparing the waste material suitable for a plasma reactor, and processing the material in the reactor. The synthesis gas created by the reactor is used to preheat the waste material by circulating the hot synthesis gas around the drum. In an alternative embodiment, the hot synthesis gas flows through the drum to preheat the waste material and to clean the synthesis gas. Different methods of cooling and cleaning the synthesis gas are used. The system may comprise two plasma reactors in combination with a rotating desorber drum.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of processing a waste product and producing synthesis gas (“syngas”) and useable solid products. More particularly, this invention relates to a method and apparatus for processing a waste product, secondary material, or other feedstock containing carbon by employing a heated rotatable drum and a plasma reactor.
2. Background of the Invention
A gasification system is generally defined as an enclosed thermal device and associated gas cleaning system or systems that does not meet the definition of an incinerator or industrial furnace, well known to those skilled in the art, and that: (1) limits oxygen concentrations in the enclosed thermal device to prevent the full oxidization of thermally disassociated gaseous compounds; (2) utilizes a gas cleanup system or systems designed to remove contaminants from the partially oxidized gas that do not contribute to its fuel value; (3) transforms inorganic feed materials into a molten, glass-like substance (“slag”) at temperatures above 2000° F.; and (4) produces a synthesis gas.
Utilizing a plasma arc to gasify a material is a technology that has been used commercially for many years. Most plasma arc reactors produce a high quality syngas that can be used as a building block for other chemical manufacturing processes or as a fuel for energy production. Many feeds containing hydrocarbons, such as oil, coal, refinery residuals, and sewage sludge have all been successfully used in gasification operations. It is sometimes desirable to convert a hazardous stream of material into a useable product by gasifying the material. Upon gasification, the hazardous material, or feed, will typically be converted into a useable syngas and a useful molten material, or a molten glass-like substance called slag or vitreous frit. Since the slag is in a fused, vitrified state, it is usually found to be non-hazardous and may be disposed of in a landfill as a non-hazardous material, or sold as an ore, road-bed, or other construction material. It is becoming less desirable to dispose of waste material by incineration or desorption because of the extreme waste of fuel in the heating process and the further waste of disposing, as a residual waste, material that can be converted into a useful syngas and solid material.
Generally, the gasification process consists of feeding carbon-containing materials into a heated chamber (the gasifier) along with a controlled and limited amount of oxygen and steam. At the high operating temperature created by conditions in the gasifier, chemical bonds are broken by thermal energy and by partial oxidation, and inorganic mineral matter is fused or vitrified to form a molten glass-like substance called slag or vitreous frit. With insufficient oxygen, oxidation is limited and the thermodynamics and chemical equilibrium of the system shift reactions and vapor species to a reduced, rather than an oxidized state. Consequently, the elements commonly found in fuels and other organic materials end up in the syngas.
However, the carbon-containing feed materials may be difficult to manage because they are typically in an improper form for gasification. Furthermore, syngas produced by a plasma reactor is usually very hot, dirty, and difficult to manage. Therefore the industry would welcome a gasification system which is self-regulating, self-cleaning, and which produces a higher quality syngas and/or useable solid by-product.
The present invention overcomes certain deficiencies of the prior art.
BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS
Disclosed is an apparatus and method for processing a waste stream wherein a heated, sealed rotatable drum preheats and prepares the waste stream for gasification within a plasma reactor. The synthesis gas (syngas) produced by the reactor is used to heat the rotatable drum and, consequently, cool the syngas. The syngas is a useable product and the molten metal, glass, and slag is useable or disposable as a non-hazardous material. The hot syngas may be blended with a colder gas and the blend used to preheat the feed. The hot syngas also may be conveyed through the inside of the rotating drum to cool and clean the gas, as well as to preheat the feed.
Another embodiment described herein includes a first plasma reactor to gasify the solid material in the feed, and a second plasma reactor to treat the untreated vapors, with the heat from the first reactor, or the second reactor, used to heat the rotating drum.
The disclosed devices and methods comprise a combination of features and advantages which enable them to overcome certain shortcomings of the prior art methods and apparatus. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed description of preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
FIG. 1
shows a schematic view of a plasma reactor.;
FIG. 2
shows a schematic view of an alternative plasma reactor;
FIG. 3
shows a schematic view of a waste processing plant using a rotating drum in combination with a plasma reactor;
FIG. 4
shows a schematic view of an alternative waste processing plant using a rotating drum in combination with a plasma reactor;
FIG. 5
shows a schematic view of a waste processing plant using a rotating drum in series with two plasma reactors;
FIG. 6
shows a schematic view of another version of a waste processing plant using a rotating drum in combination with a plasma reactor that gasifies only the solids and high boilers that process the waste; and
FIG. 7
shows a schematic view of an alternative waste processing plant using a rotating drum in series with two plasma reactors.
NOTATION AND NOMENCLATURE
Certain terms are used throughout the following description and claims to refer to particular system components. This document does not intend to distinguish between components that differ in name but not finction. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the terms “connects,” “connected,” and “interconnected” are intended to mean and refer to either an indirect or a direct connection between components or apparatus. Thus, for example, if a first apparatus “connects with” or is “connected to” to a second piece of equipment or apparatus, that connection may be through a direct connection of the two devices, such as by a conduit, or through an indirect connection via other devices, apparatus, conduits and other intermediate connections. As an even more specific example, a first apparatus may be connected to or interconnected with a second apparatus (by conduit or piping, for example) even where there is a third device or apparatus in between the two.
Further, the present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention, including an apparatus and method for processing a waste product so that it is converted into useable gases, liquids, and solids. This exemplary disclosure is provided with the understanding that it is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. In particular, various embodiments of the present invention provide a number of different constructions and methods of operation. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results.
Reference to the term “waste” or “waste product” is intended to mean any feedstock which may contain carbon which will convert to syngas or other compounds which are desirable in the gas product or other elements which may contribute to the molten products. These feedstocks may be wastes, secondary materials, or raw materials for a manufacturing process. Further the term “syngas” means “synthesis gas” which is a gas manufactured by reforming compounds through conversion processes that involve thermal disassociation and partial oxidation. In the present invention, thermal disassociation and partial oxidation reactions occur between the waste feed and cooling mediums when subjected to a plasma arc. The resulting synthesis gas is commonly understood to be primarily composed of hydrogen and carbon monoxide, however, the composition of the gas produced in the presence of the plasma arc is not critical to the present invention. The gas may include any combination of elements or compounds present in the waste feed and/or cooling medium. To the extent that any term is not specially defined in this specification, the intent is that the term is to be given its plain and ordinary meaning as understood by a person of ordinary skill in the art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is not intended to describe the complete operation of a plasma reactor, and the power supply used for powering and controlling the plasma torch of a plasma reactor, since a complete plasma reactor system, with power supply and controller, is known and can be purchased commercially. However,
FIGS. 1 and 2
are simplified schematic drawings used to illustrate the basic operation of a typical plasma reactor.
The plasma reactor of
FIG. 1
is referred to as reactor
100
. Plasma torch
102
is provided with electrodes
104
that, when energized, produce arc
106
. Plasma torch reforming and cooling medium
114
, which is usually a controlled combination of air, steam, and/or oxygen, is injected to the inside of the torch via inlets
105
as shown by FIG.
1
. When the reforming and cooling medium
114
contacts arc
106
, plasma
108
is produced that flows to the contacting chamber
110
, where the feed that is to be reformed
112
is injected and contacted by the plasma
108
. Plasma
108
is an ionized, conductive gas which is created by the interaction of a gas with the electric arc. Plasma
108
is at a controlled temperature, usually from 8,000° F. to 30,000° F.
The molecules in the feed
112
that can be gasified are disassembled to their basic atoms and certain of the metals are melted. These atoms flow to collecting chamber
121
through opening
122
and reach a temperature, usually from 2000° F. to 3000° F., in collecting chamber
121
. The molten metals and glass
123
collect in the bottom of the collecting chamber and are drawn off through outlet
124
. The silicate slag
125
floats on top of molten metals
123
and is drawn off through outlet
126
, as shown in FIG.
1
. At the lower temperature in collecting chamber
121
, the higher reactive atoms recombine and form the synthesis gas or syngas
120
. For example, one carbon atom combines with an oxygen atom and forms a carbon monoxide molecule (CO). The quantity of oxygen injected with feed
112
and reforming and cooling medium
114
is controlled since excessive oxygen combines with the carbon monoxide molecules and forms carbon dioxide (CO
2
). Accordingly, the elements commonly found in the feed (C, H, O, S, CL) end up in the syngas
120
as CO, H
2
, H
2
O, CO
2
, N
2
, CH
4
, H
2
S, HCL with lesser amounts of COS, NH
3
, HCN, elemental carbon and trace quantities of other hydrocarbons.
Syngas
120
in chamber
121
flows through outlet
128
of container
121
and to cyclone
130
through cyclone inlet
132
. Solids flow out bottom outlet
134
and cleaned syngas flows out top outlet
136
. The operation of a cyclone is well known by those familiar with the art.
Referring now to
FIG. 2
, a simplified schematic drawing can be seen depicting the basic operation of another version of a plasma reactor. The plasma reactor of
FIG. 2
is referred to as reactor
200
. The plasma torch of reactor
200
is provided with electrodes
204
that, when energized, produce arc
206
. Plasma torch reforming and cooling medium
214
flows to chamber
221
as shown by FIG.
2
. When the reforming and cooling medium
214
contacts arc
206
, plasma is produced within chamber
221
. Some reactors having special graphite electrodes which may not require a cooling medium. As feed
212
enters chamber
221
, the molecules of feed
212
are disassemble to their basic atoms. The molten metals and glass
223
collect in the bottom of collecting chamber
221
and are drawn off through outlet
224
. The silicate slag, aluminates, and other salts
225
float on top of molten metals and glass
223
, and are drawn off through outlet
226
. The higher reactive atoms recombine and form the syngas
220
which flows through outlet
228
of chamber
221
to inlet
232
of cyclone
230
. Solids collected by the cyclone, mostly carbon, flow out bottom outlet
234
of cyclone
230
and syngas flows out the top outlet
236
.
Referring next to
FIG. 3
, a process plant
300
incorporating a plasma reactor
301
is shown. The apparatus processes waste product and produces useful products including syngas, molten metals, and silicate slag that can be used for various types of construction or building material.
As shown in
FIG. 3
, process plant
300
includes a plasma reactor
301
, such as the previously described reactors of
FIGS. 1 and 2
. Reactor
301
comprises a collecting chamber
321
, a contacting chamber
310
, and a plasma torch
302
with attached cooling and reforming medium supply
314
and electric supply
315
. Molten metal flows out the bottom outlet
324
of chamber
321
; silicate slag flows out outlet
326
; and syngas
320
flows out top outlet
328
. Syngas
320
then flows through inlet
332
of cyclone
330
. Subsequently, separated solids flow out outlet
334
of cyclone
330
and clean syngas flows out top outlet
336
. Syngas
320
then flows through inlet
342
of venturi exhauster
340
, which is known to those skilled in the art and is commercially available. Syngas
320
flows out outlet
344
to the inlet
355
of outside enclosure
362
of rotating drum
360
.
Plant
300
also includes rotatable drum
360
. The operation of rotating drum
360
, as well as other features and details of drum
360
, is described in the following patents, which are hereby incorporated herein by reference: U.S. Pat. No. 5,078,836 entitled “Method and Apparatus for Retorting Material,” U.S. Pat. No. 5,227,026 entitled “Retort Heat Exchanger Apparatus,” and U.S. Pat. No. 5,523,060 entitled “Apparatus for Retorting Material.” Thus, rotating, mounting, and other means associated with drum
360
are not described herein because the components and operation of rotating drum
360
is sufficiently disclosed in the above-referenced patents.
Drum
360
is attached to stationary inlet bulkhead
363
by seals
364
and attached to stationary outlet bulkhead
366
by seals
367
. Seals
364
and
367
separate the inside of the drum from the outside. The drum is configured such that feed
311
placed through the inlet bulkhead opening
365
progresses through the drum to the outlet opening
368
. Drum
360
is enclosed by stationary enclosure
362
and attached to drum
360
by seals
351
. Enclosure
362
is provided with hot syngas
320
via gas inlet
355
and gas outlet
357
so that hot syngas
320
flows from the inlet to the outlet as shown by curves
347
, thereby heating drum
360
.
Material to be processed
311
flows into rotating drum
360
and is heated by the hot syngas
320
that flows between the outside of drum
360
and the inside of drum enclosure
362
as, shown by flow arrows
347
. In flowing through the rotating heated drum, the waste
311
is ground to a fine powder and most of the liquids are vaporized, thereby transforming material
311
into a prepared plasma feed. Prepared plasma feed
311
flows out bulkhead outlet
368
to plasma contacting chamber
310
through chamber conduit and inlet
312
. Sorter
316
, an apparatus for sorting and removing particles that are too large to be processed by the reactor, may optionally be placed in conduit
312
. Particles that are too large may be removed through line
317
and or returned to inlet line
311
or otherwise processed.
Syngas
320
flows from collecting chamber
321
out outlet
328
through cyclone
330
, venturi exhauster
340
, and drum enclosure
362
as previously described. Syngas
320
then flows through conduit
348
to inlet
352
of recirculation blower
350
. Syngas
320
flows from outlet
354
of blower
350
to driving fluid inlet
346
of exhauster
340
. Recirculation blower
350
is used to increase the flow of gas around drum
360
, thereby improving the heat transfer rate. Exhauster
340
is used to blend the hot syngas
320
coming from reactor
301
with the cooler syngas
320
coming from drum
360
so as to obtain a more manageable temperature such as, for example, between 800° F.-2000° F. Excess syngas
320
is drawn off selectively from outlet
354
by stream
337
, which is controlled by control valve
356
. Control valve
356
, well known by those familiar with the art, is usually controlled by the desired temperature of prepared feed
312
before feed
312
enters mixing chamber
310
.
After being processed by rotating heated drum
360
, the prepared feed
312
consists of vapors and pulverized solids. It is necessary to pulverize the solids since the plasma reactor
301
is unable to process lumps or larger pieces of solids. The above referenced and incorporated patents teach how the rotating drum
360
is used to pulverize the solids.
Referring now to
FIG. 4
, a schematic drawing illustrates another embodiment of the present invention combining a waste processing drum with a plasma reactor. The embodiment of
FIG. 4
may be preferred because it is more economical than the embodiment of
FIG. 3
, depending mainly on the composition of the unprepared feed. For example, in treating a feed containing a high percentage of condensables, such as water or light hydrocarbons that do not need to be processed by the plasma reactor, the embodiment of
FIG. 4
may be preferred over that of FIG.
3
.
The apparatus of
FIG. 4
is referred to as process plant
400
. Plant
400
includes rotatable drum
460
which is attached to stationary inlet bulkhead
463
by seals
464
and attached to stationary outlet bulkhead
466
by seals
467
. Seals
464
and
467
separate the inside of drum
460
from the outside. Drum
460
is configured such that unprepared feed
411
placed through the inlet bulkhead opening
465
progresses through the drum to the outlet opening
469
.
Plasma reactor
401
comprises a collecting chamber
421
, a contacting chamber
410
, and a plasma torch
402
with attached cooling and reforming medium supply
414
and electric supply
415
. Molten metal flows out the bottom outlet
424
of chamber
421
; silicate slag flows out outlet
426
; and syngas
420
flows out top outlet
428
. Syngas
420
flows through inlet
461
of bulkhead
466
. Syngas
420
then flows through the inside of drum
460
to the outlet opening
468
of bulkhead
463
. In flowing through drum
460
, the hot syngas
420
is cooled and the feed
411
is heated, vaporizing all of the water and light constituent portions of feed
411
. Drum
460
is also provided with outer shell
462
having seals
449
.
Material to be processed
411
flows through the inside of rotating drum
460
, and is heated by the hot syngas
420
which also flows through drum
460
as shown by flow arrow
429
. After being processed by drum
460
, materials to be processed
411
exit drum
460
via outlet
469
of bulkhead
466
as prepared feed
412
. Syngas
420
, as well as other vapors vaporized from the feed
411
, exits drum
460
via outlet
468
of bulkhead
463
. This exit stream
452
flows to inlet
456
of venturi scrubber
454
. Hot streams, such as stream
452
, sometimes contain large hydrocarbon molecules which vaporize in the drum, but which also may condense and foul the conduit out of the drum. Therefore, an external rotatable auger with seal (not shown) may be installed somewhere along the stream
452
conduit which can drill and clean the conduit in a few seconds, without the need to shut down plant
400
.
Syngas
420
flows from outlet
459
of venturi
454
to scrubber inlet
472
of scrubber
470
. Scrubber
470
contains demister element
478
, well known by those familiar with the art. Syngas
420
flows up the inside of scrubber
470
, as shown by arrow
474
, through demister
478
, and out outlet
479
to become product stream
436
. The liquid elements flow down the inside of scrubber
470
, as shown by arrow
476
, and out the bottom outlet
471
to the inlet
481
of pump
480
. After passing through pump
480
, the liquid elements flow out pump outlet
482
, then through air cooler
484
and out air cooler outlet
486
. The liquid stream is then divided into venturi driving stream
488
that goes to venturi driving inlet
458
and stream
491
that goes to liquid disposal stream
496
. The flow of stream
496
is controlled by control valve
492
which, in turn, is controlled by level controller
493
.
The liquid in the bottom of scrubber
470
contains some hydrocarbons and solids. Side stream
490
may be drawn off and controlled by hand control valve
494
, and centrifuged by centrifuge
495
. The solids stream
497
and the hydrocarbon stream
499
flow out of centrifuge
495
, as shown, and the water stream
498
is returned to the scrubber.
Recirculation blower
450
, burner
451
, and fuel and oxygen supply line
453
all assist in providing optional start up and/or additional heat to drum
460
. Burner
451
may optionally supply heat to the drum during startup and operation. When burner
451
is used, blower
450
recirculates hot gas from shell
462
via inlet
442
to burner
451
via outlet
444
as shown by arrow
440
. Exhaust gas flows to the atmosphere by exhaust stack
448
.
Referring to
FIG. 5
, a schematic drawing shows a further embodiment of the present invention. The apparatus of
FIG. 5
is referred to as process plant
500
. Plant
500
includes rotatable drum
560
that is attached to stationary inlet bulkhead
563
by seals
564
and attached to stationary outlet bulkhead
566
by seals
567
. Seals
564
and
567
separate the inside of drum
560
from the outside. The drum is configured by sloping the drum and/or having internal baffles (not shown) that lift and push the feed forward, as taught by the above-referenced and incorporated patents, such that feed
511
placed through the inlet bulkhead opening
565
progresses through the drum to the outlet opening
578
, yet hot gas flowing through nozzle
561
flows back through the drum to outlet
568
.
Plant
500
also includes a plasma reactor
501
. Reactor
501
comprises collecting chamber
521
, contacting chamber
510
, and plasma torch
502
extending from contacting chamber
510
and including inlets for a cooling and reforming medium supply
514
and electric supply
515
. Molten metal flows out the bottom outlet of chamber
521
through outlet
524
; silicate slag flows out outlet
526
; and syngas
520
flows out top outlet
528
. Syngas
520
flows through inlet
561
of bulkhead
566
. Syngas
520
then flows through the inside of drum
560
to the outlet opening
568
of bulkhead
563
. While flowing through drum
560
, hot syngas
520
is cooled and the unprepared feed
511
is heated, vaporizing the water and light constituents.
Feed
511
flows through the inside of rotating drum
560
and is heated by hot syngas
520
that flows through the drum as shown by flow arrow
529
, thereby forming prepared feed stream
512
. Syngas
520
, as well as other vapors vaporized from the feed, referred to as exit stream
552
, then flows out outlet
568
of bulkhead
563
and into cross exchanger
570
. Cross exchanger
570
preheats stream
552
, converting it to preheated stream
5122
, which then flows to contacting chamber
5102
of plasma reactor
5012
, the second plasma reactor included in plant
500
. Plasma reactor
5012
comprises collecting chamber
5212
, contacting chamber
5102
, and plasma torch
5022
extending from contacting chamber
5102
and having inlets for an electric power supply and a supply of reforming and cooling medium, not shown but similar to those of reactor
501
. Collecting chamber
5212
contains molten metal outlet
5242
, slag outlet
5262
, and syngas outlet
5282
. Syngas
5202
flows from the collecting chamber
5212
to inlet nozzle
532
of cyclone
530
. The solids collected by cyclone
530
flow out nozzle
534
and clean syngas flows out nozzle
536
and then through cross exchanger
570
to become a cooler syngas stream
538
.
FIG. 6
is a schematic drawing of yet another embodiment of the present invention. The apparatus of
FIG. 6
is referred to as process plant
600
. Plant
600
includes a plasma reactor
601
. Reactor
601
comprises a collecting chamber
621
, a contacting chamber
610
, and a plasma torch
602
extending from contacting chamber
610
and having inlets for a cooling and reforming medium supply
614
and electric supply
615
. Molten metal flows out the bottom outlet
624
of chamber
621
; silicate slag flows out outlet
626
; and syngas
620
flows out top outlet
628
. Syngas
620
flows through inlet
632
of cyclone
630
, with separated solids then flowing out outlet
634
of cyclone
630
and clean syngas flowing out top outlet
636
. Syngas
620
then flows through inlet
642
of venturi exhauster
640
and through outlet
644
to the inlet
655
of outside enclosure
662
of rotating drum
660
.
Plant
600
also includes rotatable drum
660
. Drum
660
is attached to stationary inlet bulkhead
663
by seals
664
and attached to stationary outlet bulkhead
666
by seals
667
. Seals
664
and
667
separate the inside of drum
660
from the outside. Drum
660
is configured such that feed
611
placed through the inlet bulkhead opening
665
progresses through the drum to the solids outlet opening
678
, and the vapors and gases produced inside of the heated and rotating drum
660
flow out the vapor outlet
658
of inlet bulkhead
663
. Drum
660
is enclosed by stationary enclosure
662
and attached by seals
651
. Enclosure
662
is provided with hot gas inlet
655
and hot gas outlet
657
so that hot gas flows from the inlet to the outlet as shown by curves
647
and heats the drum.
Feed
611
flows through the inside of rotating drum
660
and is heated by the hot syngas that flows on the outside of drum
660
and on the inside of drum enclosure
662
as shown by flow curves
647
. While flowing through the rotating heated drum
660
, the feed
611
is ground to a fine powder and most of the liquids are vaporized. The solids from this prepared plasma feed flow out outlet bulkhead nozzle
678
and the vapors flow out outlet
658
of inlet bulkhead
663
. The solids stream
612
flows to plasma contacting chamber
610
, where it reacts with the plasma and forms molten metals, silicate slag, and syngas
620
as previously described. Syngas
620
flows from collecting chamber
621
through outlet
628
, cyclone
630
, venturi exhauster
640
, and to drum enclosure
662
as previously described.
Syngas
620
then flows through conduit
648
to inlet
652
of recirculation blower
650
. Syngas
620
flows from outlet
654
of blower
650
to driving fluid inlet
646
of exhauster
640
. Recirculation blower
650
is used to increase the flow of gas around drum
660
and thereby improve the heat transfer rate. Exhauster
640
is used to blend the hot syngas
636
coming from reactor
601
with the cooler syngas coming from drum
660
(via conduit
648
and blower
650
) to obtain a more manageable temperature, such as, for example, less than 2000° F. Excess syngas is drawn off selectively from outlet stream
654
of blower
650
by stream
637
, which is controlled by control valve
656
. Control valve
656
, well known by those familiar with the art, is usually controlled by the desired temperature of prepared feed
612
before feed
612
enters mixing chamber
610
.
The vapors and gases produced inside of drum
660
flow through outlet
658
of inlet bulkhead
663
to inlet
674
of venturi scrubber
670
. The vapors and gases then flow to container
693
through venturi scrubber outlet
676
, with liquids collecting in the bottom of container
693
and gases flowing out outlet
672
to inlet
679
of scrubber
675
. Gases in scrubber
675
flow through demister element
678
and out outlet
673
, and liquids collect in the bottom of scrubber
675
and are selectively drained through outlet
677
. Venturi driving fluid pump
680
pumps liquid from container
693
through pump inlet
671
and through outlet
682
to conduit
683
. From conduit
683
, the liquids pass through cooler
684
to venturi scrubber inlet
688
. A side stream
691
can be drawn from the pump outlet
682
and becomes stream
696
that is controlled by control valve
692
. Stream
696
can include hydrocarbons, dirt, and/or water, and can be removed for separation by any separation means known in the art, including but not limited to, gravity, centrifuge, or a water treating system. Clean makeup water is returned through inlet
698
of container
693
, and liquid surface
695
is maintained and controlled by control valve
699
and level controller
697
.
FIG. 7
is a schematic drawing of a further embodiment of the present invention. The apparatus of
FIG. 7
is referred to as process plant
700
. Plant
700
includes a first plasma reactor
701
having a collecting chamber
721
, a contacting chamber
710
, and a plasma torch
702
extending from contacting chamber
710
having inlets for a cooling and reforming medium supply
714
and electric supply
715
. Molten metal flows out the bottom outlet
724
of chamber
721
; silicate slag flows out outlet
726
; and syngas
720
flows out top outlet
728
. Syngas
720
flows into inlet
732
of cyclone
730
, with the separated solids flowing out outlet
734
of cyclone
730
and clean syngas flowing out top outlet
736
. Clean syngas
720
then flows through cross exchanger
770
to become cooler product syngas stream
7382
.
Plant
700
also includes a second plasma reactor
7012
to process the vapors and gases formed in the drum
760
. Plasma reactor
7012
comprises a collecting chamber
7212
, a contacting chamber
7102
, and a plasma torch
7022
having an electric power supply and a supply of reforming and cooling medium (not shown). Gases to be reformed flow from outlet
758
of inlet bulkhead
763
through cross exchanger
770
and into inlet
7122
of contacting chamber
7102
. Collecting chamber
7212
includes molten metal outlet nozzle
7242
, slag outlet nozzle
7262
, and syngas outlet nozzle
7282
. Syngas
7202
flows from the collecting chamber
7212
through outlet
7282
to inlet nozzle
7322
of cyclone
7302
. The separated solids collected by cyclone
7302
flow out nozzle
7342
and clean syngas flows out nozzle
7362
to inlet
742
of venturi exhauster
740
. Plant
700
allows solids to be processed by the first plasma reactor
701
and the relatively clean gas feed to be processed by the second plasma reactor
7012
.
Rotatable drum
760
of plant
700
is attached to stationary inlet bulkhead
763
by seals
764
and attached to stationary outlet bulkhead
766
by seals
767
. Seals
764
and
767
separate the inside of drum
760
from the outside. Drum
760
is configured such that feed
711
placed through the inlet bulkhead opening
765
progresses through drum
760
to the solids outlet opening
768
, and the vapors and gases produced inside of the heated and rotating drum
760
flow out the vapor outlet
758
of inlet bulkhead
763
. Drum
760
is enclosed by stationary enclosure
762
and attached by seals
751
. Enclosure
762
is provided with hot gas inlet
755
and hot gas outlet
757
so that hot gas flows from the inlet to the outlet as shown by curves
747
and heats drum
760
.
Feed material
711
flows through the inside of rotating drum
760
and is heated by hot syngas
7202
that flows between the outside of drum
760
and the inside of drum enclosure
762
, as shown by flow curves
747
. While flowing through rotating heated drum
760
, waste
711
is ground to a fine powder and most of the liquids are vaporized, with the solids from this prepared plasma feed flowing out bulkhead outlet
768
and the vapors flowing out outlet
758
of inlet bulkhead
763
. The prepared solids stream
712
flows to plasma contacting chamber
710
. Syngas
720
flows from collecting chamber
721
through outlet
728
into cyclone
730
, and then via outlet
736
to cross exchanger
770
forming product stream
7382
as previously described.
Syngas
7202
flowing around drum
760
according to curves
747
flows through outlet
757
and conduit
748
to inlet
752
of recirculation blower
750
. Syngas
7202
then flows from blower outlet
754
to driving inlet
746
of venturi exhauster
740
and out outlet
744
of exhauster
740
. Cooler syngas
7202
has now been blended with hot syngas
7202
, and is returned to inlet
755
of drum enclosure
762
. Recirculation blower
750
is used to increase the flow of gas around drum
760
thereby improving the heat transfer rate. Exhauster
740
is used to blend the hot syngas
7202
coming from reactor
7012
with the cooler syngas coming from drum
760
to obtain a more manageable temperature in the range of, for example, less than 2000° F. Excess blended syngas is drawn off selectively from outlet stream
744
of exhauster
740
by stream
737
, which is controlled by control valve
756
. Control valve
756
, well known by those familiar with the art, is usually controlled by the desired temperature of prepared feed stream
712
before feed
712
enters mixing chamber
710
.
Although the present invention and its advantages have been described in relation to the specifically illustrated embodiments, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of the invention as defined by the claims. The following are some examples of such substitutions:
The hot syngas
7202
from reactor
7012
used to heat drum
760
of
FIG. 7
may be substituted with syngas
720
from reactor
701
.
A vessel with spray nozzles can be used to clean and/or cool the various gas streams, instead of a venturi scrubber. Also, there are many other known methods of cleaning and cooling gas streams.
Gas rotary lock valves or screw conveyors in the transfer lines between the drum and the reactors are not shown in the drawings, since they may or may not be required for different feeds and different modes of operation. Gas rotary lock valves and screw conveyors are well known by those familiar with the art.
Certain of the vessels in the plants described herein require internal refractory insulation and the use of particular materials to provide protection from the intense hot streams. Such methods of heat protection are well known by those familiar with the art and are not described herein.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. While the preferred embodiments of the invention and their methods of use have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are exemplary only, and are not limiting. Many other variations and modifications of the invention and apparatus and methods disclosed herein are possible and are within he scope of the invention. Accordingly, the scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. In particular, unless order is explicitly recited, the recitation of steps in a claim is not intended to require that the steps be performed in any particular order, or that any step must be completed before the beginning of another step.
Claims
- 1. The process of processing a waste material including the steps of:preparing a plasma reactor feed by preheating and pulverizing said waste material in a heated rotating drum; processing said prepared feed with a plasma reactor; removing gas created by said plasma reactor from said plasma reactor, blending said gas with a second gas stream forming a blended gas stream and circulating the blended gas stream over the outside of said rotating drum to cool said gas and heat said drum.
- 2. The process of processing a waste material including the steps of:preparing a plasma reactor feed by preheating and pulverizing said waste material in a heated rotating drum; processing said prepared feed with a plasma reactor; removing gas created by said plasma reactor from said plasma reactor, blending said gas with a second gas stream forming a blended gas stream and circulating the blended gas stream over the outside of said drum to heat said drum; and removing the water and hydrocarbon vapor from said drum and cooling said vapors to condense said water and the condensable hydrocarbon vapors to supply a stream of other gas.
- 3. The process of processing a waste material including the steps of:preparing a plasma reactor feed by preheating and pulverizing said waste material in a heated rotating drum; processing said prepared feed with a first plasma reactor; removing gas created by said first plasma reactor from said first plasma reactor to supply a first gas stream; processing with a second plasma reactor the gas and vapors created in said heated drum and removed from said drum; removing gas created by said second plasma reactor from said second plasma reactor, blending said gas with a second gas stream forming a blended gas stream and circulating the blended gas stream over said drum to heat said drum.
- 4. The process of processing a waste material and producing a gas from said waste material including the steps of:preparing a plasma reactor feed by preheating and pulverizing said waste material in a rotating drum; processing said prepared feed with a plasma reactor; removing gas created by said plasma reactor from said plasma reactor and flowing it through the inside of said drum to preheat said waste material and to vaporize the water and light hydrocarbons in said feed; removing the gas and water and hydrocarbons vapors from the drum; condensing the water and condensable hydrocarbons from the drum gas and vapors to furnish a stream of gas.
- 5. The process of processing a waste material and producing a gas from said waste material including the steps of:preparing a plasma reactor feed by preheating and pulverizing said waste material in a heated rotating drum; processing said prepared feed with a first plasma reactor; removing gas created by said first plasma reactor from said first plasma reactor and flowing it through the inside of said drum to preheat said waste material and to vaporize the water and light hydrocarbons in said feed; removing the gas and water and hydrocarbons vapors from the drum; processing said gas and vapors removed from said drum with a second plasma reactor.
- 6. A process for treating a waste material comprising:(a) introducing the waste material into a vessel; (b) heating and pulverizing the waste material under conditions effective to produce materials comprising waste powder and drum gas wherein the drum gas comprises volatile hydrocarbon components and water; (c) recovering the drum gas from the vessel; (d) subjecting the waste powder to a first plasma arc wherein the waste powder is converted to molten materials and synthesis gas; (e) recovering the synthesis gas of step (d); and (f) recovering the molten material of step (d), wherein the heating in step (b) is carried out by passing the synthesis gas from step (e) into the vessel wherein the synthesis gas mixes with the drum gas to form a combined gas mixture.
- 7. A process for treating a waste material comprising:(a) introducing the waste material into a vessel; (b) heating and pulverizing the waste material under conditions effective to produce materials comprising waste powder and drum gas wherein the drum gas comprises volatile hydrocarbon components and water; (c) recovering the drum gas from the vessel; (d) subjecting the waste powder to a first plasma arc wherein the waste powder is converted to molten materials and synthesis gas; (e) recovering the synthesis gas of step (d); and (f) recovering the molten material of step (d), wherein the heating in step (b) is carried out by at least one of (i) passing a blended gas stream comprising the synthesis gas from step (e) and a cooler gas stream around the outside of the vessel and (ii) passing the synthesis gas from step (e) into the vessel wherein the synthesis gas mixes with the drum gas to form a combined gas mixture.
- 8. The process according to claim 7 further comprising:(g) using the synthesis gas of step (e) as a heat source for the vessel of step (a).
- 9. The process according to claim 7 wherein the vessel is a rotatable drum.
- 10. The process according to claim 7 further comprising:(g) condensing the drum gas from step (c).
- 11. The process according to claim 10 further comprising:(h) recovering any unconfessed gas from step (g).
- 12. The process according to claim 7 further comprising:(g) subjecting the drum gas from step (c) to a second plasma arc wherein the drum gas is converted to materials comprising molten material, synthesis gas or both.
- 13. The process according to claim 12 wherein the synthesis gas produced in step (g) is used as the heat source for the vessel of step (a).
- 14. The process according to claim 7 wherein the heating in step (b) is carried out by passing the synthesis gas around the outside of the vessel of step (a).
- 15. The process according to claim 7 wherein the heating in step (b) is carried out by passing the synthesis gas into the vessel of step (a) wherein the synthesis gas mixes with the drum gas to form a combined gas mixture.
- 16. The process according to claim 15 further comprising:(g) separating the synthesis gas from the combined gas mixture to produce a second synthesis gas stream.
- 17. The process according to claim 16 wherein the second synthesis gas stream is produced by condensing at least a portion of the drum gas from the combined gas mixture.
- 18. The process according to claim 15 further comprising:(i) subjecting the combined gas stream to a second plasma arc wherein the combined gas stream is converted to materials comprising molten material, synthesis gas or both.
US Referenced Citations (38)