 HI's PBPV System (Revised 13Oct99 at 02:10) The Technology - HI calls its system a "Plasma-Based Pyrolysis/Vitrification" (PBPV) System. HI’s PBPV System is a one-step process capable of sustaining extremely high temperatures (approximately 3,000 degrees Fahrenheit, in the process chamber) utilizing a plasma arc torch to reduce a wide variety of hazardous and non-hazardous liquid and solid waste materials to their basic compounds or elements. The process reformulates these elements into one or more of three useful by-products: a synthetic gas (syngas) usable as a fuel or chemical feedstock, metals that can be reused, and a glass-like, vitrified solid that may be used as an aggregate or safely used as a landfill. The PBPV System is an environmentally-sound waste treatment solution suited for medical and hazardous waste streams that pose significant treatment and disposal difficulties and therefore have higher associated processing costs.
Material Feed System - The Material Feed System will be comprised of a shredder/extruder with airlock hopper for feeding solids, and a pump system for feeding reactive, hazardous, or toxic liquids. The airlock hopper will isolate the feed extruder compartment from atmosphere via two hydraulic slide gate doors with enclosed bonnets and inflatable seals. The airlock hopper will be installed directly over the feed extruder compartment to allow gravity feed charging of the extruder. The combination shredder/extruder type auger will feed waste into the PBPV System's processing chamber through a water-cooled feed tube and a rotary isolation gate valve. Steam may be injected to achieve the desired product gas composition. Process Chamber - The process chamber will be a gas-tight vessel with an insulated refractory lining enclosed by a reinforced carbon steel shell. The chamber will be specially designed for use in the PBPV System to process both liquid and solid, organic and inorganic waste streams. During processing, organic compounds will be gasified, producing a synthesis (fuel) gas. Inorganic material can be introduced in virtually any form for molten processing in the PBPV system. Metals and minerals with high boiling points collect in the chamber bottom where they react or vitrify to form a non-leachable glass. If the proportion of ferrous or nickel alloys is large enough, the melt will stratify with metal on the bottom and glass on top. Flux is added to adjust the liquid’s temperature of the glass and to create an amorphous glass as opposed to crystalline material. Both metal and glass material will be drained through a tap into a water quench handling system. The process chamber also includes a fuel gas heating system for preheating the chamber and maintaining its temperature during periods when waste is not being processed. Plasma Heating System - The Plasma Heating System will be comprised of three major components: Plasma Arc Torch, Power Supply, and Control System. A non-transferred arc plasma torch will provide the source of heat for HI’s PBPV System. This torch will be cooled using an isolated, skid mounted, closed-loop system supplied by the plasma torch manufacturer, rejecting heat to a cooling tower system. De-ionized water is preferred for the torch coolant closed-loop side. As an option, a water purification system can be included to produce the necessary treated water. The power supply will be provided with it's own controls, interlocks, and switchgear; and will be totally enclosed in a metal housing. Water-cooling will be by a closed-loop cooling system within the power supply cabinet, with treated water as the coolant. De-ionized water will be supplied from the same source as the plasma torch cooling system. Heat will be rejected to an external, closed-loop system, then to a cooling tower system. The control system will interface with the PBPV System's SCADA. Product Gas Treatment System - The Product Gas Treatment System will be comprised of the following major components: high temperature ceramic filter, quench chamber, wet scrubber, Induced draft fans (2 - one standby), scrubber liquor tank, scrubber recirculation pumps (2 - one standby), and an acid neutralization system consisting of a sodium hydroxide (NaOH) tank with mixer and metering pump. Product gas leaving the process chamber will be filtered to remove particulate, cooled in the quench tower, then treated in a packed tower scrubber to remove acid gases. Wastewater Treatment System - Blowdown water from the Quench/Scrubber, as well as all other process water discharges will be treated by a wastewater treatment system before discharge into a sewer. Glass Handling System - This system will consist of a mechanical conveyor in a water-filled upper trough. One end of the conveyor will have an incline rising out of the water. Seal plates attached to the bottom of the process chamber will be immersed in the upper water-filled trough to maintain a gas seal. Glass exiting the process chamber will be sprayed with cooling water at the discharge chute. The aggregate fragments will then fall into the quench trough and settle to the bottom. At the bottom of the quench trough, a scraper conveyor will remove the aggregate from the trough by pulling it up a dewatering slope. A detachable chute will be installed at the discharge point to direct the solidified and cooled aggregate into a collection drum. Gas Analyzer - A multi-component gas analyzer system will be provided for continuous measurement of hydrogen, carbon dioxide, carbon monoxide, methane, and oxygen. The gas analyzer will be used for process control and refinement by sending gas composition information to the control system to make adjustments to operational parameters, including feed rate and steam injection rate (only when required). Thermal Oxidizer - A regenerative thermal oxidizer consisting of two reinforced insulated chambers filled with heat exchange media, converts the syngas to carbon dioxide and water. The unit is started by heating the heat exchange media to 1500 degrees F via a propane powered process heater which is turned off once operating temperature is reached. Syngas is mixed with air and reacts in the oxidizer to form carbon dioxide and water while releasing chemical energy that maintains operating temperature in the heat exchange media. The syngas/air mixture is directed through both oxidizer chambers in series, where heat exchange media in the first chamber initiates the syngas/air reaction which, in turn, heats the media in the second chamber. Poppet valves automatically cycle to alternate syngas/air point of entry from one chamber to the other, thereby using heat stored in the heat exchange media to maintain efficient conversion of the syngas/air mixtures as low as approximately 3 % of the L.E.L. If waste streams low in organic content result in syngas content below this level, temperature below set point is sensed in the primary chamber initiating the injection of propane directly into the syngas feed duct as required to maintain operating temperature. Controls - The Supervisory Control and Data Acquisition (SCADA) system will control the PBPV System and process and record selected data on computer disks for later analysis. The control room will be a prefabricated structure with a roof, walls (with glazing), and a door. The size of the room will be 150 square feet. The environment will be controlled with a packaged combination heating and cooling unit. Energy Recovery Systems - A big advantage of the HI’s PBPV System is the generation of a usable fuel gas. The processing of organic materials produces a synthetic fuel gas that is rich in H2 and CO with a BTU content about one third of natural gas. For large system, PEAT has investigated the potential of this gas to generate sufficient energy to drive the process. For a 300 ton per day system, there can be enough electricity generated to drive the system plus produce an additional amount of energy to return to the electrical grid. Initial investigations of electrical energy recovery on smaller systems indicate that it will not produce sufficient electricity to completely power the process. This is caused by the operating efficiencies of small systems in the generation of electrical power. PEAT conservatively estimates that an energy recovery package to produce electrical power for a small system will produce enough electricity to offset approximately one third of the electrical costs. Waste heat from a micro-turbine system will be used to power an absorption chiller for facility heating and cooling.
Hawkins Industries, Inc. & HI Disposal Systems, LLC = HI Companies Mailing Address: P.O. Box 1724, Indianapolis, IN 46206-1724 USA Voice: 317-693-1265 or 800-995-1265 - Fax: 317-262-1265 or 800-973-1265 (e-mail: info@hicompanies.com - web site: www.hicompanies.com) Copyrighted © 1997 1998 1999 2000 by Hawkins Industries, Inc., - All rights reserved TERMS & CONDITIONS - The material contained on "www.hawkinsindustries.com or www.hidisposalsystems.com" may not be re-published, re-broadcast, re-written or re-distributed without prior written permission from Hawkins Industries, Inc. |
