PRESS RELEASE

CADDET – the Centre for the Analysis and Dissemination of Demonstrated Energy Technologies – published a brochure titled “Turbine Generator Uses Clean Gas from Sawdust Combustion,” Aerospace Research Corporation successfully negotiated with Pennsylvania Power & Light to open a continuous wood byproduct-burning plant in Pennsylvania.

The technology has attracted a great deal of international interest. According to Joseph Hamrick, president of Aerospace Research Corporation, Haiti, Costa Rica, Jamaica, Indonesia, New Zealand, the Dominican Republic and other countries have expressed interest in the technology.

Construction for a wood-burning gas turbine plant in Walker Township, Pennsylvania, was completed recently. This plant generates 12 MW per hour, or 72,000 MW a year. According to Hamrick, the plant will generate between 25 and 30 percent more revenue than is needed to make the monthly financing payments on the $6,000,000 plant.

The new technology developed by Aerospace overcomes the technical hurdles in using sawdust and other wood waste byproducts to fuel a turbine generator to produce electricity. Thus, not only is there a new market for waste wood byproducts, which often are simply disposed of, but these wood byproducts are being converted into energy, thereby reducing the amount consumed by other fuel sources, including nonrenewable ones.

The new process allows wood byproducts, such as sawdust, to be burned and converted into gas to supply a gas turbine, which in turn generates electricity. Wood burns too slowly and produces too much ash to be used as a fuel for conventional gas turbines, but the new process sidesteps these obstacles with an innovative approach.

The brochure described the demonstration of the technology at a gas turbine plant in Red Boiling Springs, Tennessee. Figure 1 shows the operating principle of Red Boiling Springs’ gas turbine. The new system produces clean gases for the turbine by burning partially dried pulverized poplar and oak wood chips at 1450F° (787C°). The sawdust, dried to about 25 percent moisture, is fed through the rotary air lock feeder into the combustion chamber where it is burned in the air delivered from the compressor. The swirling effect of the cyclone combustor ensures that residence time is adequate to completely burn all solid particles. Any remaining ash is removed from the combustion products as they pass through a single cyclone filter en route to the turbine. The turbine drives a 3 MW generator and produces electricity and heat. The heat byproduct is then used to dry the sawdust before it enters the combustion chambers. Both a primary and a secondary combustor are used. Without the second combustor, unburned char can move into the cyclone and burn, causing overheating of the walls and thus shortening their life.

A number of technological hurdles were overcome thanks to information and experience gained by the demonstration of the technology at Red Boiling Springs. For example, it was learned that overheating can occur if sawdust has accumulated in the bottom of the primary combustor. Solving this problem required three different steps: first, thermocouples were installed in the bottom of the combustor; second, an air jet was used to disperse accumulated sawdust; and third, quick acting values were installed to dump compressor air.

Wood byproduct-fired turbines of this type can provide a low-cost source of energy for areas where conventional methods are prohibitive. In addition, they provide a means of recovering energy from material that now poses disposal problems.

Hamrick sees enormous potential for the technology developed by his company. Additional refinements to the technology, driven in part by inquiries from potential international customers, have resulted in the process accepting other waste products for fuel. Sugar cane begasse, sorghum begasse, coffee bean hulls, wind grass, and other biomass can be used, making the process even more attractive to developing countries.

For more information about the innovative technology to use wood waste (and other biomass) as a fuel source, contact Joseph Hamrick of Aerospace Research Corporation at 1-540-427-3014 or send a request for information to Aerospace Research Corporation, 5454 Aerospace Road, Roanoke, VA 24014.

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