Here are some of the most frequently asked questions about the IET's Plasma Enhanced Melter(TM) systems.

FAQ: Design

Question: How much automation is provided to minimize labor cost?

Answer: A typical system is fully automated, except for assuring that all supplies and waste are present in their appropriate storage/feeder systems for feeding to the PEM™, replenishing the graphite electrodes, intermittent draining of the molten glass into receptacles, removal of scrubber system filters and removal of the filled containers of glassy residue.

Question: Can you build a system smaller than the Model 4 PEM™? For example, could you build a system to process 0.5 metric ton per day.

Answer: The primary limiting factor in manufacturing small PEM™ systems is the need to maintain a physical size large enough to receive the waste with minimal pretreatment.

Question: Does a PEM™ process waste in batches or is the waste fed constantly via an auger or conveyor, or in the case of liquids, a pipe?

Answer: The type of mechanism used for introducing the waste into the system is dependent upon the waste being processed. Continuous feeding of the waste, such as through a screw conveyor for solids and a pipe or tube for liquids and gases, provides the highest operating rates and the highest level of efficiency. However, some wastes are placed in containers at the point of generation, such as medical waste. It is frequently more efficient to process these wastes in their containers on a batch basis than to attempt to convert the waste to a bulk form.

Bulk and batch systems are both equipped with a nitrogen injection system to minimize the volume of air introduced into the PEM™ chamber and to prevent the escape of process gasses from the chamber while waste is being introduced.

Question: Are the PEM™ system inner furnace bricks resistant to chlorine?

Answer: The characteristics of the refractory brick and materials in a PEM™ are carefully matched to the specific application to assure maximum refractory life, even when processing chlorinated wastes. Also, the system is operated in a manner that minimizes the corrosive effects of chlorine on the refractory materials. The materials of construction of the off-gas treatment system are also compatible with the contaminants in the gas, including chlorine.

Question: What is the rate of consumption of the graphite electrode material?

Answer: The PEM™ has two sets of electrodes, which are consumed at different rates. The size of the electrodes increases as the size of the system increases. For a Model 4 PEM™, the electrodes are made up of sections that are about 0.6 meters (2 feet) in length and 15 cm (6 inches) in diameter.; For most wastes, each of the three AC electrodes, which maintain the temperature of the molten glass residue, require addition of one section of graphite electrode material every 3 to 4 weeks. Each of the three DC electrodes, which provide the plasma energy, requires the addition of one length of electrode every 2 to 3 days when processing organic wastes and one length every week when processing inorganic waste, such as ash from municipal waste incinerators.

The electrodes are replenished by attaching a new section to the top of the electrode. The top of the electrode is outside the PEM™. The electrode is inserted into the PEM™ through a sealed control mechanism that automatically feeds the electrode into the PEM™ at the required rate. It is not necessary to open the PEM™ chamber to replenish the electrodes. It is, of course, necessary to turn off the electrical power to the PEM™ while replenishing the electrodes, which takes about 15 minutes.

Question: How much space is required for the equipment required for removal of the vitrified glass from the PEM™?

Answer: For small systems, the vitrified glass is typically collected in and disposed in 100 liter or 200 liter containers. The weight of these containers, when filled with glass residue, is approximately 500 kg and 1000 kg, respectively . The receiving container is placed inside a containment cylinder that is attached to the PEM™ by a collar. This unit has metal wheels that rest on short sections of track to allow the filled container to be easily rolled aside when it is full. The empty container is positioned below the outer diameter of the PEM™ processing unit. At least 6 feet of space is required for extension of the track for removal of full containers.

Question: What is the largest diameter of the waste entry port available for the Model 4 and Model 10 PEM™?

Answer: For the Model 4 it's 45cm(18in.), Model 10 it's 60cm(24in.)

Question: Which PEM™ model is large enough to process automobile tires whole?

Answer: The Model 10 PEM™ has a waste entry opening that is 60cm. in diameter and is the smallest PEM™ system that is able to process whole tires from automobiles.

Question: We would like to process municipal waste and used tires in the same system using the same feeder mechanism. Is this possible?

Answer: Yes, this is both possible and advantageous because of the high level of excess energy produced from tires.

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