Mobile material decontamination apparatus

Abstract: A technique for decontaminating material, including disposing a grid network of perforated pipes on a base, and covering the same with contaminated soil. A barrier layer is laid on the contaminated material and provided with a vent port coupled to a vapor disposal unit via a suction system. A source of heated gas is coupled to the grid system to force heated air through the contaminated soil and vaporize the contaminants. A mobile decontamination system includes an insulated container (464) having a top lid (470) for loading contaminated material in the container, and an insulated back door for removing decontaminated material. Apertured pipes (506) on the container floor convey a high temperature gas to the contaminated material to vaporize the contaminants. A suction system is coupled to a vapor outlet (526) of the container (464) to remove vaporized contaminants. The contaminated vapors are incinerated and either discharged as a harmless gas, or recirculated to the container for providing thermal energy and further vaporizing contaminants in the material.

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates in general to the treatment of materials to remove toxic or unwanted substances therefrom, and more particularly relates to the treatment of excavated soil to remove or obviate the effects of the toxic or undesirable substances. BACKGROUND OF THE INVENTION In recent years, a special awareness or interest has been placed on the quality of the environment. This has been due, in a large part, to the realization that many substances, both old and newly developed, can lead to present and future detrimental effects. Chemicals and toxic materials which adversely affect the air, earth or water present a serious concern as to the storing of such substances, and the subsequent environmental cleanup in the event of contamination of the environment by the inadvertent release of such materials. One environmental concern that has prompted recent investigation and remedial action is that caused by petrochemical spills and leakages into the earth due to defective containers or pipelines. The oil, gas or fuel which contaminates the soil, if not checked, can pollute the soil as well as contaminate groundwater supplies and aquifers. One technique which has been employed effectively to decontaminate soil is to excavate the contaminated area and to process the soil through a kiln at an elevated temperature. While such a technique is effective, it is apparent that the time, cost and labor is appreciable and not cost effective for large contaminated areas. The in situ treatment of contaminated soil has been carried out by use of neutralizing chemicals and solvents, as well as nutrients and microorganisms to promote in situ biodegradation of the contaminants. In addition, in situ soil flushing has been carried out by injecting solvents or surfactants into the soil to enhance the contaminant solubility. This technique involves the drilling of an extraction well in the contaminated soil zone, the drilling of reinjection wells upgradient of the contaminant area, and the construction of a waste water treatment system. Subsequent to the soil treatment, the groundwater is reinjected upgradient of the extraction well, which then leaches through the contaminated soil. The leachate is then collected, treated and reinjected back into the system, creating a closed loop system. Yet another in situ treatment of contaminated soil involves a process in which production wells are drilled through the contaminated soil zone to a depth just above the water table. Monitoring wells are drilled around the production wells to monitor pressure gradients. A vacuum is then applied to the production wells. Because of the horizontal pressure gradient created in the soil zone by the vacuum pumps, volatiles in the soil percolate and diffuse through the air spaces between the soil particles to the production well. The vacuum established in the soil continuously draws volatile organic compounds and contaminated air from the soil pores, and draws free air through the soil surface down into the soil. The volatiles removed from the monitoring wells are then processed through a liquid-vapor separator. This procedure applies no heat input and is limited in both the rate of contaminant removal and the types of contaminants which can be vaporized. In another variation of the foregoing technique, the treatment system includes injection wells for injecting steam, hot air and liquid chemicals into the churned soil. Extraction wells operating in a partial vacuum environment provide a horizontal pressure gradient in the soil. The mixture heats the soil and raises the temperature of the chemicals, eventually causing them to evaporate. The evaporated chemicals are drawn horizontally to the extraction wells and piped to a processing system that cools the chemical vapors for conversion into a liquid. The liquid chemicals are then further processed by an incinerator to detoxify the contaminants. One disadvantage of this technique is that the steam is prone to condense in the soil and form a liquid barrier to the further movement of contaminants to the extraction wells. Another disadvantage is that the soil temperature cannot be raised substantially above 100°C (212°F) to remove less volatile contaminants. In US-A-4,670,634, there is disclosed a technique for decontaminating soil by the use of radio frequency energy to heat the soil. Electrodes located over the surface of the decontaminated area radiate RF energy into the soil and heat the soil to the extent that gases and vapors are produced. The rising gases and vapors are collected by a vapor barrier which operates under a slight vacuum. While the system appears to be effective, the energy requirements are substantial and costly, and the depth of the heat penetration into the soil is limited. In those in situ decontamination systems where the soil is heated to either vaporize or oxidize the contaminants, there is the recurring problem of how to deliver the energy to the contaminated zone in the most efficient manner. As noted above, in heating the soil with RF energy, such a technique is costly and time consuming. Experimental in situ decontamination efforts have been carried out in which hot gases generated by surface heaters are carried by ducts and forced into injection wells. Since there is a limit to which air can be heated, conveyed and injected, there is a corresponding limitation to which the subsurface soil contaminants can be heated. As a result, soil contaminants characterized by low volatilities, such as polychlorinated biphenyls (PCBs), are difficult to remove from the soil as they require substantially high soil temperatures. US-A-5,011,329, assigned to the assignee hereof, discloses a technique for carrying out the in situ decontamination of earth material, such as petroleum contaminated soil. According to such technique, bore holes are formed in the contaminated earth material and cased with a perforated casing. Hot air is forced in the cased bore holes, and into the contaminated earth material until the contaminants either are vaporized or oxidized. A surface extraction system, comprising a barrier layer coupled to a suction or vacuum pump, removes the contaminated vapors for incineration or other disposal. While this technique is highly effective to decontaminate the soil, it is not readily mobile and is not practical for surface decontamination or soil and materials that are saturated with moisture, where the moisture or ground water cannot be readily or economically removed. While many of the foregoing techniques are effective in providing decontamination of the soil, many of the shortcomings attendant with such techniques are that the processes incur high operating expenses which are not practical for small volumes of contaminated material, require expensive equipment or chemicals, some techniques are limited in the rate at which energy can be introduced into the soil and as a final result are not effective for small volumes of soil or where the soil is heavily water saturated and not readily removable. The reference DE-A-4 037 743 discusses the use of a vertical column in which contaminated material is carried downwardly on a screen, and air is blown upwardly to remove contaminants. A conveyor carries the raw material to the top of the column where it falls onto the uppermost portion of the screen to be carried downwardly. The reference EP-A-405 067 discloses two embodiments of a container for removing contaminants from the material. In one embodiment, the contaminated material is dumped on a flat table and a dome cover is placed over the material. An inert gas, such as air, is passed through the contaminated material via perforated pipes to collect the contaminants and pass the same to activated charcoal units. Heat exchangers are utilized to cool the air before it is forced into the container so that the charcoal units remain operable. In another embodiment, a steel container is utilized with a side door for rolling into the container wire mesh carts filled with contaminated material. Perforated pipes allow the compressed air to be dispensed into and through the contaminated material. Contaminated vapors are collected at the top of the container and passed to the charcoal filters, much like the first embodiment. DE-A-3 907 946 discloses the use of a mobile container having a hinged lid and a burner for heating the contaminated material. The vaporized contaminants then escape to the atmosphere by way of an exhaust vent. From the foregoing, it can be seen that a need exists for an improved technique to remove contaminants from a material in an efficient and cost effective manner. Yet another need exists for an efficient utilization of energy, in which combustion gases used in heating the injection gas are reused for injection into a mobile decontaminator to raise the temperature so that volatile and less volatile contaminants can be vaporized from the contained material. Yet another need exists for a technique to deliver high temperature gases to a mobile piping grid system or a container to achieve oxidation of low volatile contaminants. SUMMARY OF THE INVENTION In accordance with the invention, soil decontamination apparatus as defined in claim 1 and corresponding techniques as claimed in claim 19 are disclosed which substantially reduce or eliminate many of the shortcomings associated with the prior art techniques. According to an important feature of the invention, a mobile containment vessel includes an opening for loading the container with excavated contaminated material. Subsequent to the decontamination process, the decontaminated material is removed from the vessel via the same opening or a different opening in the side of the container. The container is an insulated vessel that includes an interior circulation system for forcing hot gases via an injection inlet into the container to vaporize the contaminants, and a vapor outlet for recovering contaminated vapors for incineration or other processing or disposal thereof. In the preferred embodiment of the invention, a system of perforated pipes is fabricated on the floor of the container so that the hot air emitted therefrom is forced through the contaminated material to increase the temperature thereof. As the contaminants reach a temperature of vaporization, the contaminants are vaporized and removed at the top of the system via the vapor outlet where the pressure is less than that at the injection inlet. In accordance with another feature of the invention, a mobile hot gas circulation system includes a blower/burner assembly to provide a source of hot gas coupled to the perforated injection pipes within the container. A high-temperature incinerator or other disposal system is connected to the vapor outlet of the container for incinerating the vapor contaminants and discharging the same as harmless gases into the air. According to another embodiment of the invention, a closed-loop circulation system includes a blower/burner having an inlet connected from the container vapor outlet, and an outlet for forcing hot gases into the perforated injection pipes via the injection inlet to form a closed loop system. In the closed-loop system the high-temperature vent gases removed from the container via the vapor outlet are coupled to the burner for reheating, incineration and reinjection into the perforated injection pipes. In addition, perforated exhaust pipes are disposed between the perforated injection pipes, with the exhaust pipes extending through the sidewall of the container. The exhaust pipes have adjustable valves therein for controlling the extent of gases exhausted from the system to the atmosphere. In this manner, a controlled amount of the incinerated vapors passing through the burner back to the container are conveyed from the injection pipes to the exhaust pipes and exhausted. With this path of recirculated gases, the residence time is increased, and complete incineration is assured. An aggregate may be placed between the injection pipes and the exhaust pipes to facilitate the incineration process. Additionally, a reactive material, such as limestone, can be placed in lieu of or in addition to the aggregate for reacting with chlorinated hydrocarbon gases to remove the hydrogen chloride and allow the resulting harmless gases to be exhausted from the system. A fresh air make-up inlet is provided with the closed loop system for replacing substantially the same volume of air that is discharged by way of the exhaust pipes. A highly efficient system is realized by reusing the high-temperature vent gases for recirculation through the system to vaporize additional contaminants in the material within the container. When the contaminated material comprises water-saturated soil, the excess moisture is drained by way of liquid drain formed at the bottom of the container, and thereafter capped during the operation or the blower-burner. The decontamination process is carried out in the following manner. The contaminated material is first loaded into the container and allowed to set so that water or moisture can be drained off through the liquid drain outlet. The container is then closed and sealed, whereupon a hot gas at a temperature of about 649°C (1200°F) to about 871°C (1600°F) is forced by the burner/blower assembly into the container so that the remaining water moisture is evaporated and removed from the system. After a soil temperature of about 100°C (212°F) has been reached and substantially all of the water vapor has been removed, the soil temperature further increases to vaporize and/or oxidize the contaminants. The maximum temperature to which the soil is raised depends upon the temperature by which the contaminants become vaporized. If a closed-loop type system is employed, a certain portion of the vaporized contaminants are incinerated and removed from the system, and the remaining vent gas is reheated and again recirculated for continued vaporization of the contaminants. The same volume of vent gas that is incinerated and output from the system is supplied as make-up air to thereby support combustion in the burner. In accordance with another aspect of the invention, the entire system is made mobile by fabricating the blower/burner assembly separate and apart from the containment vessel. The blower/burner assembly can be transported on a trailer, as can be the containment vessel, and connected together at the destination either by rigid or flexible insulated tubing. BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the present invention will become apparent from the following and more particular description of the preferred embodiment of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same or similar elements or functions throughout the views, and in which: FIG. 1 is a side view of a mobile decontamination system, showing the blower/burner assembly coupled to a containment vessel; FIG. 2 is a partially sectioned rear view of the containment vessel illustrating the structural features of the floor and sidewalls of the container; FIG. 3 is a partial cross-sectional view of the container lid and sidewall, with the seal assembly therebetween; FIG. 4 is a top view of the container with the lid removed; FIG. 5 is a plan view of the container lid, as viewed from below; FIG. 6 is a rear view of the container of the invention with the door thereof shown in an opened position; FIG. 7 is a cross-sectional view of a portion of the lid, with the container rear sidewall in the sealed engagement of the container door; FIG. 8 is a cross-sectional view of another embodiment of a perforated floor structure for use with the container; FIG. 9 is a side view of the container of the invention, with the lid shown removed therefrom and the back door latched to the container; FIGS. 10a and 10b are top views of the door latching mechanism, shown with the latching apparatus in different positions; FIG. 11 is a frontal plan view of another embodiment of the decontamination container of the invention; FIG. 12 is a side plan view of the container of FIG. 11; FIG. 13 is a schematic diagram of the decontamination system of the invention; FIG. 14 is a sectional view of an arrangement of aggregate disposed on the floor of container decontamination unit; FIG. 15 is a sectional view depicting the use of a solid fuel in the container decontamination unit; FIG. 16 is a flow chart of the steps carried out to decontaminate material using the mobile material decontaminator of the invention; FIG. 17 illustrates a burner adapted for fixing to a casing head for heating and injecting hot air directly into a vertical injection well of the invention; and FIG. 18 is a cross-sectional view of an adapter for utilizing a burner in horizontal air flow situations. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 depicts an embodiment of a material decontamination system 460 that is well adapted for decontaminating small volumes of excavated, contaminated material, and that can be readily moved from location to location. The system 460 includes a skid-mounted burner/blower assembly and vapor disposal equipment, and a skid-mounted containment vessel 464 in which contaminated material can be loaded from the top and removed from the back. The burner/blower assembly is coupled to the container 464 by a first flexible pipe 466 for removing vaporized contaminants from the container 464, and one or more other flexible pipes 468 for coupling pressurized, hot air to the container 464. Although the insulated flexible piping is convenient, the connections between the equipment skid 474 and the container skid 476 can be rigid pipes, preferably insulated. Also shown is a removable lid 470 for loading contaminated dirt or other material into the container 464, and a hinged door 472 that can be opened to remove decontaminated material therefrom. While the burner/blower assembly and the container 464 can be fabricated as an integral unit, it is preferred for purposes of mobility that the burner/blower assembly be mounted on a skid 474 so that such assembly can be placed within an empty container 464 and transported together. The container 464 itself is also mounted on a skid 476 to provide a base and for allowing movement in the locale of the contaminated material. In the preferred form of the invention, the burner/blower assembly includes three gas-powered burners 480, a compressor 482, a bank of catalytic converters 484, and a control panel 486 for manually controlling the operation of the system 460. While not specifically shown, the burners 480 are coupled to a single combustion chamber that has four outlets, each coupled to a corresponding injection pipe of the container 464. FIG. 2 is a front plan view of the container 464 with the lid 470 shown removed upwardly from the container. In the preferred embodiment of the invention, the container 464 is about 6.1m (twenty feet) long, 2.4m (eight feet) wide, and 2.14m (seven feet) tall so that it can be transported on a trailer on public highways. The container 464 can accommodate about 31.7-34.5 metric ton (35-38 ton) of material, but preferably is not loaded completely full in order for a small air space to exist at the top thereof. The container 464 is of a double wall construction having an inner metal sidewall 500 of 6.34mm (quarter inch) carbon steel spaced apart from an outer 6.34mm (quarter inch) sidewall steel plate 502 by about 3.8cm (one and one-half inches). Disposed between the sidewalls 500 and 502 is a 2.54cm (one inch) thick board-type insulation 504 to increase the thermal efficiency of the unit. Particularly, an insulation of the type Enerok 1200/80 that is bonded together at its ends and to the inner sidewall 500 with a Sairset AP Green Mortar. An air space 505 thus exists between the insulation 504 and the outer sidewall 502. With an insulated container 464, much of the heat energy is utilized to vaporize contaminants and little heat energy is lost through the sidewalls. The container 464 is a rigid unit with all metal seams welded, and with spaced apart upright steel supports (not shown) in the sidewalls, and to which the inner and outer walls 500 and 502 are welded. The decontamination container 464 is described herein as being constructed using double sidewalls, with insulation therebetween. However, an alternate sidewall construction can have a single, sturdy inner sidewall, with insulation disposed on the outer surface thereof. With this sidewall arrangement, vertical channels can be welded to the four sidewalls so that the board-type insulation identified above can be inserted in the channels and held against the outside surface of the inner sidewall. During transportation, the insulation can be removed so that it is not damaged. The lid 470 can be similarly constructed and insulated to achieve a more cost effective container unit. Multiple injection pipes, one shown as reference number 506 are spot welded to the floor of the container 464 to provide ducts for carrying hot air to the interior of the container 464. Each injection pipe 506 is 10.16cm (four inches) in diameter. Further, each injection pipe 506 has nineteen 1.27cm (one-half inch) holes formed on each lateral side thereof, staggered with respect to the holes on the other side, so that hot air can exit the pipes outwardly on opposite sides of the pipes at the 38 locations. The injection pipes 506 are each constructed of 316 type stainless steel and spot welded to the bottom of the container 464. In this manner, liquid that is drained from contaminated material can run under the injection pipes 506 to a central liquid outlet 508 formed at a front, lower corner of the container 464. The liquid drain 508 comprises a pipe extending through the double sidewall and can be capped to prevent the escape of hot air during the decontamination process. Each air injection pipe 506 includes a flange 510 that can be coupled either to the flexible pipe 468 extending from the burner/blower assembly, or to a rigid connection pipe. The container 464 is mounted on a skid 476 comprising an "H" beam shown as reference character 512 extending along each side of the container 464, as well as an H-beam extending centrally under the floor of the container 464. Each H-beam has welded thereto a lateral front and rear pipe 514 to fix the ends of the H-beams together. Each H-beam is welded to the bottom of the container 464 to make an integral and rigid structure. Further shown in FIG. 2 is the removable lid 470 which also includes a double wall, insulated construction. The general surface of the lid 470 includes an inner 3.17mm (eighth inch) carbon steel sidewall 520, an outer 3.17mm (eighth inch) carbon steel sidewall 522, with 3.8cm (one and one-half inches) of insulation 524 interposed therebetween. The peak of the lid 470 comprises a 15.24cm (six inch) diameter vapor outlet pipe 526 for withdrawing contaminated vapors from the material within the container 464. Eyelets 527 are welded to the outlet pipe 526 for lifting the lid off the container 464. The end of the vapor outlet pipe 526 has a flange 529 welded thereto. The inner and outer lid sidewalls 520 and 522 are welded to the vapor outlet pipe 526 which extends the entire length of the lid 470. As illustrated, the lid 470 includes a peripheral skirt 528 that fits down over the outer sidewall 502 of the container 464. As will be described in more detail below, the lid 470 includes an inner peripheral planar ledge that presses down tightly on a seal assembly 530 formed around the top edge of the container 464 to provide a seal. In the preferred embodiment of the invention, the lid 470 weighs about 0.9 metric ton (one ton) and thus the weight thereof provides a compressive force on the seal assembly 530, thereby also sealing the unit from the escape of contaminated vapors. FIG. 3 illustrates a cross-sectional view of a portion of the lid 470 and a portion of the container sidewalls and the engagement therebetween. As can be seen, the skirt 528 of the lid 470 extends somewhat beyond the outer sidewall 502 of the container 464 so that the lid 470 can rest securely on top of the container 464 and cannot shift laterally when in place. Fabricated atop the double sidewall of the container 464 is the seal assembly 530 for sealing to the planar ledge 534 of the lid. The seal assembly 530 includes a metal channel 536 welded to the top edge 538 of the container sidewall. The channel 536 is welded around the peripheral edge 538 so that no leaks can occur under the channel 536. Fastened within the channel 536 is a packing rope 540. The packing rope 540 extends substantially above the channel 536 and deforms when the lid 470 rests thereon, thereby providing a seal. In the preferred form, the packing rope 540 can withstand temperatures of 1093°C-1204°C (2000-2200°F) and is obtainable from McMaster-Carr Supply Company, Chicago, Illinois. The seal assembly 530 is also shown in the top plan view of FIG. 4. A view from the under surface of the container lid 470 is shown in FIG. 5. Shown in phantom are the internal supports 546 formed between the inner and outer walls 520 and 522 for support purposes. As can be seen, the vapor outlet pipe 526 extends the entire length of the lid 470 and includes a plurality of holes 550 for drawing therein vaporized contaminants. The vapor outlet pipe 426 includes a total of five, 7.62cm (three-inch) holes evenly spaced apart along the length of the pipe. A plan view from the backside of the container 464 is shown in FIG. 6. The container 464 includes a double wall door 472 hinged to the container sidewall by three hinges, one shown as reference numeral 552. The hinges 552 are welded to the container as well as to the door 472. Like the sidewalls of the container 464, the door 472 is fabricated as two 6.34mm (quarter inch) steel plates spaced apart 3.8cm (one and one-half) inches. A board type insulation is placed between the door sidewalls to provide thermal insulation to the unit. While not shown, the door 472 is constructed with internal reinforcement to provide rigidity thereto and prevent distortion thereof due to heavy loading thereon, especially when water logged earth material is dumped in the container 464. The door opening edge of the container 464 also includes a seal assembly 554 that provides a hermetic seal between the container sidewalls and the door 472. The door seal assembly 554 is shown in more detail in FIG. 7. In this figure, the double wall door 472 is shown sealed against the back opening of the container 464, and with the lid 470 resting in a sealed relationship thereon. As described above, the lid 470 is sealed to the container top edge by way of the seal assembly 530. The door seal assembly 554 is constructed similarly, with a channel member 556 welded to the back edge sidewall 502 of the container 464, and with a packing rope 558 held in the channel. The packing rope 558 provides a tight seal with respect to the inside wall of the door 472. As can also be appreciated from FIG. 7, when the lid 470 rests on the top edge of the container 464, the lid skirt 528 extends downwardly in overhanging relationship with respect to the top of the hinged door 472. In this manner, once the lid 470 is placed on the container, the hinged door 472 cannot be opened. To that end, the skirting 528 of the lid 470 provides additional support to the hinged door 472 against internal loads within the container 464. While not shown, one or more support rods can be utilized to hold the container sides by turnbuckles so that the sides do not bow outwardly under loads. With reference back to FIG. 6, one injection pipe 506 is shown sectioned to illustrate the location of the perforations 562 and 564. The injection pipe 506 includes a first hole 562 and an offset second hole 564. As noted above, the holes are 1.27cm (half inch) in diameter and formed in a staggered manner in the opposing sidewalls of the injection pipe 506. The holes 562 and 564 formed laterally in the injection pipes 506 tend to prevent material from falling into the injection pipe 506 and obstructing the flow of hot air therethrough. The injection pipes 506 also provide support and rigidity to the bottom of the container 464. The other injection pipes are shown with the back ends thereof capped by screw-on caps 560 secured to internal threads of the pipes. The removable caps 560 allow debris and other particles to be removed from the injection pipes 506, should such pipes become clogged or obstructed with contaminated material loaded in the container 464. Advantageously, decontaminated material can be removed from the container 464 by opening the door 472 and scooping the decontaminated material out of the container 464 with a front end loader, or the like. Although decontaminated material located between the injection pipes 506 may not be easily removed, such remaining material is not significant. An alternate floor construction of the container 464 is shown in FIG. 8. Here, a double wall, insulated floor structure is shown with spaced apart metal plates 570 and 572 with thermal insulation 574 disposed therebetween. Attached to the floor wall 572 is an apertured metal floor plate 576 spaced apart and supported by I-beam members 578. The I-beam members 578 may be welded to one wall structure and screwed or riveted to the other. The floor plate 576 is apertured with a number of holes 579 to allow hot air forced into the floor chambers 580 and 582 to be directed upwardly through the holes 579 and into the contaminated soil loaded on the floor. The front end of the floor chambers 580 and 582 are connected either to a manifold (not shown) with flanged injection pipe inlets or directly through inlets to a source of hot air. The back end of the floor chambers 580 and 582 can have access plates for cleaning residue that may have fallen through the holes 579, and in addition would have a liquid drain pipe for removing contaminated liquid that has drained from the material. Those skilled in the art may devise of many other types of apertured floor structures that can withstand the loads anticipated as well as provide ducting for the distribution of hot air into the container 464. The container door 472 is locked in a closed condition with "over the center" type of latches, as shown in the side view of the container unit depicted in FIG. 9. The door latch assembly 590 comprises a pair of lever-operated latches that securely hold the door 472 in a sealed relationship with the back edges of the container 464. Although a pair of lever-operated latches 590 are shown, additional or other types of latching mechanisms may be utilized. Also shown are a number of pluggable instrumentation ports 592 for use in inserting thermocouple probes or other instrumentation apparatus inside the container 464 to monitor the progress of the decontamination process. Temperature or instrumentation ports 592 are spaced vertically in the container 464 so that the temperature gradient of the material in the container can be monitored to assess the progress of the decontamination cycle. When not used, the instrumentation ports 592 can be capped to prevent the escape of the contaminated material or hot air. Preferably, after the container 464 is loaded with a material to be decontaminated, but before the decontamination process is commenced, a thermocouple probe can be inserted through the port 592 and partially into the material to monitor temperature, moisture or other parameters. After the material has been decontaminated, the probes are removed before removal of the decontaminated material from the container 464. FIGS. 10a and 10b illustrate in more detail the lever-operated latches for maintaining the hinged door 472 in a closed and sealed condition. FIGS. 10a and 10b are top views of a portion of the container sidewall 600, the back peripheral edge 602 of the container and the hinged door 472. The lid seal assembly 530 as well as the door seal assembly 554 are also shown. The latch assembly 590 includes a door tab, shown as numeral 604, welded to the vertical edge of the door 472. A pair of connecting members, an upper one thereof shown as numeral 608, is hinged to the door tab 604 by a pin 606. Fastened in a hinged manner between the upper and lower connecting members 608 is a handle 610. The handle 610 is hinged by means of a pin 612, or the like. A short end of the handle 610 includes a camming surface 614 for engagement with a block 616 welded to the container sidewall 600. The latch parts are fabricated so that when the camming edge 614 of the handle 610 is engaged with the block 616, and the handle 610 forced clockwise, as shown in the drawings, to an over center position, the container door 472 is tightly secured against the seal assembly 554. The latched condition of the container door 472 is shown in FIG. 10b. As noted in the drawing, the handle 610 is rotated so that an elongate portion thereof is flush against the container and is disposed between an upper and lower lock tab 620. When in such a position, a bolt or rod 622 can be inserted through a hole in the locking tab 620 to maintain the latch in a locked position. Also noted in the drawings, the handle 610 is slightly angled along its length so that an end 624 is spaced from the container outer sidewall and grasping thereof is facilitated. Many other locking arrangements may be devised by those skilled in the art to secure the door 472 to the container 464. FIGS. 11 and 12 illustrate another embodiment of a decontamination unit adapted for incinerating the vaporized contaminants. The container 630 can have single or double sidewall construction, as described above, and insulated to increase the thermal efficiency. However, in this embodiment, the lid 632 functions solely as a cover to the container 630, without vapor outlets. Rather, one or more vent gas outlets 634 are constructed in the frontal sidewall of the container 630, preferably at the top in the air space area. It is contemplated that three 15.24cm (six-inch) diameter flanged pipes fabricated into the frontal wall of the container 630 will provide adequate area for removal of contaminated vapors from the container 630. Formed at the back part of the container 630 are one or more fresh air ports 636 functioning to admit fresh air into the container 630 for mixing with the contaminants that have been vaporized from the contaminated material loaded into the container 630. It is contemplated that a pair of fresh air ports 636, each having an opening of about 30.48cm (twelve inches) by 15.24cm (six inches) will provide adequate area for admitting a sufficient volume of make-up air to support combustion of fuel utilized to generate the thermal energy required in removing the contaminants from the contaminated material. While not shown, the fresh air ports 636 are open to the atmosphere, but can be provided with covers to prevent moisture or rain from entering the container. The container 630 utilizes the injection pipes 506 welded to the container floor, as described above in the previous embodiment. The injection pipes 506 are flanged for connection to individual combustion chambers and associated burners, or connected to a manifold which, in turn, connects to one or more burners. Disposed between the injection pipes 506 are a number of exhaust pipes 638. FIG. 14 illustrates an exhaust pipe 638 supported slightly above the floor 640 of the container 630, and disposed between adjacent injection pipes 506. As noted, the injection pipes 506 each have holes formed laterally in the side walls thereof, while the exhaust pipes 638 have holes 642 formed in the bottom thereof, about 1.27cm (one-half inch) off the container floor 640. Plural holes 642 are formed along the bottom surface of each exhaust pipe 638. The back end of each exhaust pipe 638 is capped, while the front of each such pipe 638 extends through the frontal sidewall of the container 630, but is sealed therearound by welding, or the like. Further, and as illustrated in FIG. 12, each exhaust pipe 638 extends through the front sidewall of the container 630 and is directed upwardly above the top of the container for exhausting harmless gases into the air. Each vertical section 644 of the exhaust pipes includes an adjustable valve 646 that can be manually adjusted to control the flow of gases exhaust through the pipes 644. As will be explained in more detail below, the valves 646 are utilized to indirectly control the volume of fresh air admitted to the system, the combustion in the burners, and thus, the temperature of the system. One or more stand offs 648 may be utilized to space the vertical section 644 of the exhaust pipes from the container, thereby facilitating movement of the lid 632 with respect to the container 630. A closed loop system employing the container of FIGS. 11 and 12 is shown in FIG. 13. The vent pipes 634 are each connected to the input of a respective blower 482, the output of which is connected to a respective burner 480. Each burner 480 has an output coupled to a combustion chamber 481, and the output of the combustion chamber 481 is connected to the flanged input of the injection pipe 506. As can be seen from FIG. 13, the only air inlet to the closed loop system is via the fresh air inlets 636, and the only outlet of the system is via the exhaust pipes 644. As will be explained in more detail below, the valves 646 directly control the volume of gases exhaust from the system, which volume is less than the volume circulated through the system, thereby assuring incineration of the contaminated vapors. In order to assure a sufficient residence or contact time of the incinerated vapors, an exhaust to the system is provided out of the container 630, rather than at the output of the combustion chamber 481. Because of the relatively short contact time in the burners 480 and the associated combustion chambers 481, it is possible for trace amounts of hydrocarbons to escape destruction, due to imperfect mixing. An increased contact time of hydrocarbons and other contaminated vapors is provided by the structure illustrated in FIG. 14. Here, an aggregate 650 is shoveled, or otherwise placed between the injection pipes 506 and the exhaust pipes 638. Preferably, the aggregate 650 is of a loose composition for allowing the flow of hot air therethrough, but is sufficiently large so as not to clog the holes in either the injection pipes 506 or the exhaust pipes 638. For processing material contaminated with hydrocarbons, the aggregate 650 can be small rocks or stones capable of withstanding the 871°C (1600°F) temperatures of the hot air injected into the pipes 506 and forced out of the holes in the sidewalls thereof. As can be appreciated, the aggregate 650 also becomes heated such that the hot air which is passed through the burner 480 and the combustion chamber 481 also passes through the hot aggregate 650 and exits the system via the exhaust pipes 638. It should be noted that the only gases that pass from the injection pipes 506 to the exhaust pipes 638 are incinerated gases, not the contaminated vapors. As noted above, the rate at which the gases exit the system depends on the setting of the valves 646. The gases that pass from the injection pipe 506 to the exhaust pipes 638 is thereby controlled, and the path thereof is increased due to the aggregate 650, thereby increasing the residence time and assuring complete destruction of the contaminants. Preferably, the contact time of the gases depends on the type of aggregate and to the extent compacted, the exhaust rate of gases from the system, the spacing between the injection pipes 506 and the exhaust pipes 638, as well as other parameters. It is contemplated that the contact time utilizing the present invention will be greater than one second so that at 649°C-816°C (1200°F-1500°F), the reaction goes to completion and only harmless gases are discharged into the atmosphere. As further noted in FIG. 14, the hydrocarbon contaminated material 652 can be loaded directly on the aggregate 650. The aggregate 650 need not be replenished every time a new load of contaminated material is processed. The aggregate 650 can advantageously benefit the incineration process, especially when processing chlorinated hydrocarbons. When decontaminating chlorinated hydrocarbons, a hydrogen chloride gas is given off, which gas cannot be vented to the atmosphere. Rather, the hydrogen chloride gas itself must be removed before being exhausted to the atmosphere. Hence, when processing chlorinated hydrocarbons, the aggregate 650 can be graded and sized limestone such that when the hydrogen chloride passes therethrough, calcium chloride is formed, thereby tying up the chlorine in the aggregate 650. Limestone is an inexpensive and readily available aggregate that can be utilized in the bed of the container 630, in the path of the incinerated gases before being exhaust from the system. Other types of aggregate 650 can be utilized, such as iron shavings which, when reacted with hydrogen chloride, results in ferric chloride. Other aggregate materials such as sodium hydroxide and soda ash can also be utilized to destroy the hydrogen chloride gases and allow harmless gases to be exhausted to the atmosphere. FIG. 15 illustrates another technique which increases the efficiency of the decontamination process carried out in either of the container embodiments described above, although FIG. 15 illustrates the apparatus of the container described in connection with FIGS. 11 and 12. An aggregate 650 is utilized around and above the injection pipes 506 and the exhaust pipes 638. Disposed above the aggregate 650 is a layer of solid fuel 654, such as coal. Other solid fuels can be utilized. Preferably, about a 2.54cm-5.08cm (1-2 inch) layer of coal can simply be spread over the aggregate 650 so that when ignited, a source of heat internal to the container 630 is provided. In view that a solid fuel, such as coal, burns at a temperature of at least 1260°C (2300°F), a substantial amount of thermal energy is generated, thereby expediting the decontamination process. As described above in connection with the embodiments utilizing solid fuel, the solid fuel can be ignited by hot air and then utilized as the sole source of thermal energy, or can be utilized in conjunction with the heat generated by a burner 480. The aggregate 650, or other material is utilized to prevent the floor and other metal structures of the container 630 from becoming too hot and susceptible to destruction. An operational sequence for carrying out the decontamination process is illustrated in flow chart form in FIG. 16. The decontamination process is commenced by loading the container 630 with the contaminated material 652, leaving a sufficient air space above the material to allow the passage of the mixed contaminated vapors and fresh air to the vapor outlet 634. This is shown in block 660 of the flow chart. According to block 662, the excess liquid, if any, in the contaminated material 652 is allowed to drain out through the open drain 508. Liquid drainage can be facilitated by compressing the top of the contaminated material 652 with the bucket of a front end loader, or the like. Alternatively, excess liquid can be allowed to drain by simply allowing the material to remain for a period of time, such as 12-24 hours. Thereafter, temperature probes are inserted into the ports 592, the drain 508 is closed and the container 630 is closed, as noted in block 664. The blowers 482 are activated to start hot air circulation in the system and then the burners 480 are ignited. The exhaust pipe valves 646 are adjusted for a combustion chamber temperature of about 816°C (1500°F). Evaporated water and moisture are the first byproducts generated from the contaminated material 652 during the early stages of the contamination process. The process flow block 666 illustrates activation of the equipment, and step 668 shows the moisture vaporization step which continues while the temperature of the material 652 increases to around 93.3°C-121°C (200°F-250°F). A number of temperature probes disposed in the instrumentation ports 592 can be utilized for measuring such parameter. After a substantial amount of moisture has been removed from the contaminated material 652, the temperature of the contaminated material continues to increase because of the hot air forced into the container via the injection pipes 506. A pressure differential of about 41E+3 to 68.3E+3 Pa (3-5 psig) exists between the top and bottom of the contaminated material 652. A maximum pressure exists at the bottom of the container 630, and essentially atmospheric pressure in the air space at the top. About 22.7m 3 (800 SCFM) of air is compressed to about 41E+3 to 156.5E+3 Pa (3-8 psig), and heated by the burner 480 with a fuel, such as propane or other suitable fuel. As noted above, one or more burners 480 heat the compressed air to about 871°C (1600°F), or higher, as measured in the combustion chamber 481. The hot air enters the bottom of the container 630 and is forced upwardly from the holes in the injection pipes 506 through the contaminated material 652 which continues to rise in temperature and give off vapors, depending upon the type of contaminant and the temperature of volatilization thereof. This is depicted in block 670. The temperature of the contaminated material 652 is elevated gradually to an end point of about 482°C (900°F) or even higher to vaporize and oxidize all the contaminants. During the course of the temperature rise of the material 652, hydrocarbon contaminants are vaporized in an order of declining volatility, up to a temperature where none of the contaminants are sufficiently volatile to vaporize, namely, about 343°C-399°C (650-750°F). During the course of the temperature rise of the material 652, the remaining water content is also vaporized, providing a reduction of partial pressure of the water insoluble hydrocarbons in the vapor phase, and thus increasing the driving force for vaporization of less volatile hydrocarbons. The water is evaporated over the initial temperature range from ambient to about 100°C (212°F), except for a very small amount of absorbed capillary moisture which may require temperatures ranging upwardly to about 149°C (300°F). This adsorbed moisture is of little consequence, and for all practical purposes may be ignored. The temperature at which the soil moisture is vaporized depends on the water vapor holding capacity of the air employed. Typically, most of the water initially evaporates between 60°C-77°C (140-170°F). During the decontamination process, the exhaust pipe valves 646 are adjusted to control the volume of incinerated gases removed from the system, which corresponds to the amount of fresh air entrained into the system. Since full combustion in the burners 480 is dependent on the availability of sufficient fresh air or oxygen, the valves 646 are adjusted to obtain optimum burner efficiency which, with the type of burners utilized, comprises a combustion temperature of about 816°C (1500°F). With insufficient fresh air, the temperature will drop, which is an indication to the operator to open the valves 646 to achieve a combustion chamber temperature of 816°C (1500°F). The temperature of the incinerated gases exhaust via pipes 644 is very close to the combustion chamber temperature. Importantly, the only valves controlling the volume of air and gases circulated in the system are the exhaust valves 646. It can be appreciated that the pressure differential between the ends of the exhaust pipes 644 is essentially equal to that in the contaminated material 652, and is controlled by the valves 646. It is contemplated that for every volume of incinerated gases vented through the exhaust pipes 644, about three volumes of gases will be circulated through the contaminated material 652, although a range of about 1:1 to 5:1 will provide acceptable results. After the volatile hydrocarbons have been removed by vaporization, the involatile hydrocarbons, if any, are removed by slow oxidation occurring as the material 652 continues to be heated to 427°C-482°C (800-900°F), as shown in block 672. At temperatures above about 343°C-371°C (650-700°F), it is not necessary to incinerate or dispose of the vent gases and vapors since at such temperatures no volatile hydrocarbons are present. In a closed loop decontamination system such as shown in FIG. 13, the vent gases are mixed with sufficient make-up air to support combustion, the mixture being recycled through the blower 482 and the burner 480, and the contaminated material 652. As noted above, it is contemplated that about 2-4 volumes of vent gas per volume of make-up air comprise the mixture that is recirculated through the burner/blower assemblies to be reheated and injected into the container 630. The burner 480 consumes the hydrocarbon vapors in the vent gas, which augments and reduces the amount of primary fuel required by the burner 480. The injection burner discharge is coupled via the combustion chamber 481 to the injection pipes 506 for a residence time greater than one second, before at least a portion of the incinerated gas is vented to the atmosphere. The volume of gas exhausted from the system is replenished to the system as make-up air drawn in through the ports 636. The quantity of gas vented is controlled to maintain sufficient oxygen in the burner 480 and thus maintain the combustion chamber temperature at about 871°C (1600°F). If insufficient gas is vented, then the make-up air will be insufficient also, and the temperature within the system will begin to fall. Since the system is closed between the intake port 636 of the container 630 and the exhaust pipes 644, the make-up air, which enters and mixes with the vent gas from the material will automatically equate to the amount of incinerated gas discharged to the air. If excessive gas is vented, then oxygen available in the make-up air will exceed that needed to maintain the burner 480 at 871°C (1600°F), and the control of the temperature will revert to regulation of the amount of primary fuel. It can be appreciated that the amount of gas vented to the atmosphere can be increased within a suitable control range. Since the output of the blower 482 and burner 480 are preferably fixed, increasing the vent gas beyond that which provides a stoichiometric amount of oxygen to the burner 480, results in lower flow and thus slower heating of the contaminated material 652 and thus should be carefully monitored. In accordance with an important feature of the closed system of the invention, since about 2-4 volumes of air are passed through the contaminated material 652 for every volume vented, the amount of heat removed or exiting the system through the vent gas is greatly reduced. In other words, in contrast with a system in which all vent gases are first incinerated, or otherwise disposed of, and then exhausted, substantial energy is also lost. In the closed-loop system shown in FIG. 13, a substantial portion of the energy is maintained and recirculated in the system, thereby increasing the efficiency. In accordance with another feature of the invention, the requirements for incineration of the vaporized contaminants is reduced, as the recirculated vapors are incinerated in the high temperature burner 480 and reused as heated gases for further vaporization of the contaminants in the material 652. The recirculation of a portion of the vent gases is shown in flow diagram block 674. A safety feature of the recycling system is also available. If the material 652 is excessively contaminated, the vent gases could have more than enough fuel to sustain temperature in the burner 480 (above a lower explosion concentration), in which event the vent gases cannot explode in the air space above the material 652 because the oxygen content will be insufficient. The result of this is that smoke will be noticed in the gases vented to the atmosphere. Corrective steps include reducing the primary fuel to maintain combustion chamber temperature, and throttling the burner 480 to reduce the amount of vent gases being cycled to the burner 480 until the smoke disappears. As noted above, it is contemplated that the recirculation system will be operable for 10-12 hours to increase the temperature of the contaminated material 652 from about 65.5°C (150°F) to 100°C (212°F) for removal of moisture. Thereafter, the continued increase in temperature of the material 652 from about 100°C (212°F) to about 482°C (900°F) may take about ten hours, depending upon the type of material and extent of contamination. As noted above, the material temperature can be measured at various locations within the container 630 by the use of the probes inserted into the instrumentation ports 592. When the top portion of the material 652 reaches a temperature of about 482°C (900°F), it can be assured that most of the hydrocarbon contaminants have been vaporized and oxidized, whereupon the burner 480 can be turned off. Such steps are shown in block 676. The blower 482 is maintained operational (block 678) for a period of time to gradually cool the system down, as well as cool the decontaminated material in the container 630. The exhaust valves 646 can be opened to bring in substantial cool outside air to facilitate the temperature reduction of the system. It is contemplated that about four-five hours will be necessary to reduce the temperature of the system so that the container 630 can be opened, preferably by way of the hinged door 472 to remove the decontaminated material. This final step of the process is shown in flow diagram block 679. In the foregoing remediation systems, the source of hot air or gases is generated from a location remote from the actual perforated pipes, whether installed vertically in the ground, or horizontally in the ground or on the surface of the ground. While burners are available for generating the high temperature air required for volatilization and oxidation of contaminants, a certain amount of thermal energy is lost in transferring the heat to the perforated piping systems. Indeed, even though the surface pipes are insulated, the thermal energy lost between the burner and the perforated pipes can be as much as 149°C (300°F). With such an energy loss, the efficiency of the system is compromised. FIGS. 17 and 18 depict a technique for improving the efficiency of a hot gas remediation system by employing one or more burners connected directly to the perforated pipe, as shown in FIG. 17, or to a manifold as shown in FIG. 18. With regard to FIG. 17, there is illustrated a casing 680 having perforations (not shown) along its length for dispersing the hot gases into the contaminated formation. A high temperature refractory material or mortar 682 is filled in around the upper portion of the casing 680 for withstanding the high temperatures experienced at the upper portion of the casing 680. A combustion chamber 684 is adapted for mounting a high temperature burner 686 to the casing 680. The combustion chamber 684 comprises an upper high temperature chamber 688 and a reducer 690 that is fixed by way of a flanged arrangement 692 to the casing 680. The combustion chamber 684 is constructed of a refractory material, such as Brick Cast 3000. In the preferred embodiment of the invention, the cylindrical portion of the combustion chamber 688 has an inside diameter of about 11.2cm (4.4 inches), and is about .762m (2.5 foot) in height. Another flanged arrangement 694 allows the burner 686 to be bolted directly atop the combustion chamber 688. The burner 686 has a fuel inlet 696 and is fired by natural gas, or other fuels. A compressed air line 698 is connected to the top of the burner 686 for providing a supply of compressed air thereto so that the air can be heated and forced into the casing 680. Burners adapted for operating with pressurized air sources are available from Eclipse Combustion Division as type 84-10TBH. By providing a substantially constant stream of pressurized air to the burner 686, the output temperature thereof can be controlled by regulating the flow of fuel via line 696. FIG. 18 illustrates the burner 686 coupled to a right angle combustion chamber 700. In this embodiment, the combustion chamber 700 allows the burner 686 to remain operating in an upright position, while redirecting the hot gases laterally into the manifold 392. It should be noted that a burner 686 and corresponding combustion chamber 700 can be connected to one or more of the manifold sections 394, with the unused manifold sections capped at the flange 396. In order to provide an efficient distribution of hot air to the manifold 392, a single burner assembly (FIG. 18) can be connected to the center manifold section, or if two burner assemblies are utilized, they can be connected to the second and fourth manifold sections. With regard to FIG. 18, the carbon steel end plate 702 is formed integral with the refractory material of the combustion chamber 704, as is a similar end plate 706 to the other face of the combustion chamber. A stainless steel flanged member 708 is welded to the end plate 702 and thereby fixed to the body 704 of the combustion chamber. The flanged member 708 has formed therein threaded studs 710 for fastening a flanged part of the burner 686 thereto. Threaded studs 712 are similarly fixed with respect to the end plate 706 so that the entire burner assembly can be fastened to the manifold 392. In order to withstand the substantial high temperatures generated by the burner 686, the combustion chamber body 704 is formed of a refractory Brick Cast 3000 material. A coupling 714 is formed in the refractor combustion chamber body for instrumentation purposes. Further, a pair of eye members 716 are formed integral with the combustion chamber body 704 to allow lifting or otherwise support to the burner assembly. In view of the embodiments shown in FIGS. 17 and 18, those skilled in the art may readily realize that horizontal-operating burners can be utilized with similarly constructed combustion chambers so that the generation of the thermal energy can take place directly at the entrance of the perforated piping systems. While the preferred and other embodiments of the invention have been disclosed with reference to specific hot gas injection apparatus and methods, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims: Apparatus for decontaminating material of the type having a mobile container (464) including a side door (472) and a plurality of apertured pipes (506) disposed in the container (464) for dispensing a heated gas, a container outlet (526) for removing the contaminants, a lid (470) removable from the container (464) for loading contaminated material into the container (464), a burner/blower (480, 482) for producing high temperature hot gasses to the plurality of apertured pipes (506) that are fixed in said container (464) to thereby heat the contaminated material to vaporize the contaminants, a fresh air inlet (636) for admitting fresh air to support combustion in said burner (480); characterized by: a coupling pipe (466) connected to said outlet (526) of the container (464) for coupling the vaporized contaminants to an inlet of said burner (480) for recirculation to said container (464) of the hot gasses and partially incinerated contaminants; an exhaust outlet (644) and path to increase a residence time for complete incineration of a portion of the vaporized contaminants to thereby result in the release of harmless gases via said exhaust outlet (644); and a valve (646) for controlling the amount of harmless gasses released and for controlling the amount of fresh air admitted to the burner (480). The apparatus of Claim 1, further including means for recirculating vapors incinerated by said burner (480) as a heated gas through the contaminated material. The apparatus of Claim 1, wherein said container (464), the outlet (526), the burner/blower (480, 482) supplying hot gasses to the apertured pipes (506) comprise a closed loop system for the recirculation of vaporized contaminants, and said fresh air inlet (636), said exhaust outlet (644) and said valve (646) control a volume of gas input and exhaust from the container (464), which volume is less than the volume of contaminated gasses recirculated. The apparatus of Claim 1, wherein said blower (482) forces heated air into the container via said apertured pipes (506). The apparatus of Claim 1, further including a combustion chamber (481) connected to said apertured pipes (506), said high temperature burner (480) connected to said combustion chamber (481), and said blower (482) providing pressurized air coupled to said burner (480). The apparatus of Claim 1, wherein said lid (470) includes a seal (540) for sealing to said container opening, and including an apertured pipe (526) extending along a length of the lid (470), said apertured pipe (526) for drawing vaporized contaminants therethrough. The apparatus of Claim 6, wherein said lid (470) includes a skirt (528) that fits over sidewalls of the container (464). The apparatus of Claim 7, further including a hinged door (472) attached to one sidewall of the container (464), said lid skirt (528) overhangs a portion of said door (472) to provide support thereto. The apparatus of Claim 1, wherein said container (464) is mounted on a first skid (476), and further including in combination said blower (482) for pressurizing air to be heated by said burner (480), and wherein said burner (480) and blower (482) are mounted on a second skid (474), and wherein said second skid (474) is fittable within said container (464) opening and transported with said first skid (476). The apparatus of Claim 1, wherein said outlet (526) and said apertured pipes (506) are connected respectively to an inlet and outlet of a burner/blower assembly (460). The apparatus of Claim 1, wherein said apertured pipes inside said container (464) are adjacent said exhaust outlets (644) for exhausting a portion of incinerated vapors to the atmosphere. The apparatus of Claim 11, wherein said exhaust outlets (644) comprise the only outlets of said container (464). The apparatus of Claim 11, further including a material (650) disposed between said apertured pipes (506) and said exhaust outlets (644) for removing hydrogen chloride. The apparatus of Claim 1, wherein said container outlet (526) is formed integral with said lid (470). The apparatus of Claim 1, wherein the container (464) is double walled (500, 502) with an insulating material (504) therebetween. The apparatus of Claim 1, further including a liquid drain (508) located in a bottom portion of said container (464). The apparatus of Claim 1, wherein said apertured pipes (506) are each fixed in a floor structure of the container (464) for supporting thereon the contamination material. The apparatus of Claim 1, wherein said burner (480) produces hot gasses in the temperature range of at least 649°C-815.5°C (1200°F-1500°F) to thereby heat the material and vaporize the contaminants therefrom. A method of decontaminating a material including the steps of loading contaminated material through an opening (470) into a container (464) and closing the opening to prevent a general escape of contaminated vapors, heating a gas with a burner (480) and forcing the heated gas into the container (464) via apertured pipes (506) to vaporize contaminants and force the vaporized contaminants out of an outlet (526) of the container (464), recovering the vaporized contaminants from the outlet (526) and coupling the vaporized contaminants to an inlet of the burner (480) to incinerate the vaporized contaminants and fresh air to said burner (480) to support combustion, the method being characterized by the steps: recirculating the incinerated contaminants back to the apertured pipes (506) to further vaporize additional contaminants in the material; coupling a portion of the incinerated contaminants from the apertured pipes (506) inside the container (464) to an apertured exhaust outlet (638) to be exhausted from the container (464) as a harmless gas via an exhaust pipe (644); and controlling the amount of harmless gas exhausted via said exhaust pipe (644) by a valve (646), which also controls the amount of fresh air coupled to said burner (480). The method of Claim 19, further including supplying the fresh air to the burner (480) via a fresh air inlet (636) connected to the container (464). The method of Claim 19, further including throttling the amount of incinerated contaminants passing through the apertured exhaust pipe (644) with the valve (646) to thereby control the efficiency and temperature of combustion of said burner (480). The method of Claim 19, further including passing the incinerated contaminants between said first and second apertured pipes (506, 638) through a hot aggregate (650) for increasing a contact time of the incinerated contaminants. The method of Claim 19, further including passing the incinerated contaminants between said first and second apertured pipes (506, 638) through a medium (654) to remove chemicals from the incinerated contaminants. The method of Claim 19, further including opening a side door (472) and shoveling the decontaminated material from the container (464). The method of Claim 19, further including heating the gasses to a temperature of at least 649°C (1200°F) before admitting the gas to the apertured pipes (506). The method of Claim 19, further including passing hot gasses through a plurality of combustion chambers (700) and into the apertured pipes (506). The method of Claim 19, further including collecting vaporized contaminants via a plurality of apertures of a pipe (526) fixed to a lid (470) that is removable from the container. The method of Claim 19, further including fixing a skid structure (476) under the container (464). The method of Claim 19, further including fixing a burner/blower assembly (460) to a skid (474), said assembly (460) for providing hot gasses to the container (464) via the apertured pipes (506). The method of Claim 19, further including constructing a burner/blower assembly (460) of a size so as to be placed in the container (464) for transportability thereof. The method of Claim 19, further including constructing the container (464) with double sidewalls (500, 502) with an insulation (504) therebetween.

Inventors: HRUBETZ MICHAEL G, NELSON JOSEPH M, HRUBETZ, MICHAEL G., NELSON, JOSEPH M.
Applicants: HRUBETZ ENVIRONMENTAL SERVICES, HRUBETZ ENVIRONMENTAL SERVICES, INC.
Application year: 1992
Main classification: B09B3
IPC codes: B09C1, E21B43, F23G7