Keeping in touch with some of my old firefighter brothers and now actively involved in the Power Generation Industry, we are learning – unfortunately through passed major industrial explosions involving the accumulation of combustible powder – that accidents have mainly occurred when operators underestimate, or dismiss entirely, the devastating potential of combustible particulate solids.

A mechanical failure within the conveyor system can cause enough heat buildup to start a coal fire. Inadequate lubrication in the bearing of a roller or the friction between a seized roller and the conveyor belt can buildup heat sufficient to ignite a coal laiden belt.

Although many such incipient fires may not have been as widely advertised as Russia’s recent Sayano-Shushenskaya hydro-electric castastrophy, they have occurred. (John Cowdrey will also point out that even this devistating catastrophy hasn’t hit the main-stream U.S. media.) Plant Operators throughout our industry speculate that the frequency of incidents may be rising with small contained fires occurring regularly at many plants.

To be explosive, coal dust must have a large enough volatile ratio (determined by laboratory analysis), a small enough particle size, and sufficient quantity. Coals with a volatile ratio greater than 0.12 are considered a dust explosion hazard. This category includes PRB and bituminous coals but not anthracite coals. Bituminous and anthracite coals burn, but only bituminous coals explode.

The National Fire Protection Association’s NFPA 654 standard (Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids) warns that only 1/32 of an inch of dust over 5% of a room’s surface area presents a significant explosion hazard and makes the following recommendations:

• Minimize the escape of dust from process equipment and ventilation systems.

• Use dust collection systems and filters.

• Prefer surfaces that minimize dust accumulation and facilitate cleaning.

• Provide access to all hidden areas for inspection purposes.

• Inspect for dust residues in open and hidden areas at regular intervals.

• Clean dust residues at regular intervals.

• Use cleaning methods that do not generate dust clouds, if ignition sources are present.

• Only use vacuum cleaners approved for dust collection.

• Locate relief valves away from dust hazard areas.

• Develop and implement a formal program for performing hazardous dust inspections, testing, housekeeping, and dust control using defined methods at defined intervals.

Although the driving technology is not new, improvements have continually been made in this area of our industry with control systems, generators, and turbines to increase efficiency, reliability and output.

The most common of these newer turbines is the Pelton wheel, which is basically a series of cups attached to a hub (under the baby blue cover in the pictures of Manitou Unit #2). A jet of water is aimed at the cups and the resulting force on the cups causes the turbine to spin. Electricity is subsequently created by the relative motion between magents and conductive windings inside the gray & red generator.

Other types of turbines include the Turgo, Crossflow and various axial flow turbines, where the shaft through the center of the turbine runs in the same direction as the water flow, much like a boat propeller.

The first hydroelectric power plant was built in 1882 in Appleton, Wisconsin to provide 12.5 kilowatts to light two paper mills and a home. Today’s hydropower plants generally range in size from several hundred kilowatts to several hundred megawatts, but a few mammoth plants have capacities up to 10,000 megawatts and supply electricity to millions of people.

Worldwide, hydropower plants have acombined capacity of 675,000 megawatts and annually produce over 2.3 trillion kilowatt-hours of electricity. Our nation’s largest hydropower plant is the 7,600 megawatt Grand Coulee power station on the Columbia River in Washington State. The plant is being upscaled to 10,080 megawatts, which will place it second in the world behind a colossal 13,320 megawatt plant in Brazil.

Hydropower supplies 9 percent of the country’s electricity, accounts for 49 percent of all renewable energy used in the US. And after cutting my teeth in this industry with a couple of good people in a coal-fired plant, I am excited to be working on the forefront of renewables.

Change is good ;)