Pulse Drying What is it?

Pulse Drying Pulse drying is a relatively new technique for rapidly drying high moisture/medium solids feed streams into a much more manageable dry powder form.

How does it work? The basis for the technology is the use of a pulse combustion burner. The burner, which is similar to the pulse burner used in the Fulton Boiler Company heaters, is aerodynamically designed to produce a pulsating gas flow within the burner system, along with the heat release, which is used for evaporation. In a continuously operating pulse burner the divergent exhaust nozzle amplifies the discreet detonations into an approximately 250 hertz waveform in the downstream hot exhaust gases. This combination of pressure waves and heat is used for drying free flowing, high moisture and medium solids feed streams.

The Pulse jet

What will it accomplish? The availability of drying systems and simple user friendly equipment for remediation of contaminated sludge in all developed and developing nations and in economically depressed nations is unlimited.

What will it accomplish? There are many reasons for this, mostly of an economic nature. The availability of sites for development in the developing nations and the emergent economies is limited because many potential sites are contaminated by hazardous, radioactive or chemical waste. Before any development can take place it is first necessary to clean up these waste streams and unusable sites.

What will it accomplish? This needs to be done using a simple and cost effective system, which can be relocated to these sometimes technologically and logistically isolated areas. The very high-tech complex approach being pursued in the developed nations is and may always be unavailable to these remote locations because of their high operating and disposal costs and their complexity of operation.

A mobile unit

A stationary unit

The Pulse burners

A schematic

The process The combustion gases travel into the Pulse Drying section (a divergent nozzle) where the water is evaporated from the atomized sludge mixture. This process greatly increases the surface area of the particulate exposed to the hot gases and encourages the outward migration of internal water to the molecular level. A multi stage cyclone is then used to separate the dried particulate from the vapors and dust created by the process and a particulate filter is employed to collect the dust emerging from the cyclone. Finally HEPA filters are employed to remove any remaining traces of dust from the exhaust. At this point in the process the temperature of the gas stream is less than 300 F.

The installation The Pulse Dryer System is a self-contained process that can be rapidly mobilized at almost any location. The whole Drying System and its Control Module may be mounted on a road capable trailer. The only requirements at the site are a support pad, electrical and a fuel supply. Additional shielding and ventilation that may be required for greater than low-level radioactive sludge can be added at the site. Arrangements can be made for filter change-out, initial sludge treatment and final product handling. The electricity and gas requirements total about 50 Kw, 440v/60Hz 3 Phase and a supply of propane, natural gas or liquid fuel. Sound shielding can be provided as required.

The operation Several options are available for the packaging of the final dry product. Metal Drums or High Integrity Containers, for some wastes, binders can be added of different types including clays for the disposal of mixed wastes. It would also be possible to vitrify the dry product if desired. Following completion of the project Pulse Dryers modular construction allows for ease of disassembly with a minimum of contaminated components which can be easily cleaned for re- use or free-release.

The cost Cost analyses depends on the job requirements including raw feed volume, labor, fuel costs and environmental requirements. There are presently two mobile units available that would reduce the capital/rental cost by a significant amount. Upon receipt of a purchase order it would take from 3 to 6 months to be in the field and ready to process. Local permits will effect the ultimate schedule. Assembly at the site for the dryer takes only a few days. The construction and materials of the System are robust and there are relatively few wearable parts. It is anticipated that maintenance costs will be negligible compared with the revenue volume that this equipment will produce. Hence the cost of processing will be related to the accumulated throughput for the system.

Summary The most efficient drying process known Simple to understand and operate Mobile, can go just about anywhere Available on short notice Low man-power usage (1 person per shift) Is self-contained Works 24 hours per day if required