The Special Challenges Of Powder River Basin Coal

By Author: Conspec Controls
Total Articles: 15
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Many coal-fired power plants have switched from traditional high-sulfur bituminous coal to Powder River Basin (PRB) coal. PRB coal offers several advantages: it has a low sulfur content, reserves are plentiful, and it can be acquired using surface mining methods.

However, the increased use of PRB coal has presented special challenges in fire prevention at power plants. PRB coal has a lower BTU and higher moisture content, and produces more dust than regular bituminous coal. Fires in PRB coal-burning facilities have ranged from minor fires in coal piles to major events that have cost millions of dollars. The PRB Users Group recommends carbon monoxide (CO) detection for fire prevention in bag houses and silos

Along with the increased moisture of PRB coal comes the increased potential for spontaneous combustion. As the moisture in the coal is liberated and the coal oxidizes, both heat and carbon monoxide are created. Heat can build up to the point at which spontaneous combustion can occur.

Powder River Basin (PRB) coal's propensity to self-ignite presents an exceptional hazard, requiring special fire prevention ...
... and automatic detection and suppression efforts.

Due to its friability, PRB coal requires more stringent housekeeping methods, such as proper maintenance of stockpiles, guarding against accumulations of coal in the fuel-handling system, compaction of stockpiles, cleaning spills and washing float dust. An effective fire-mitigation plan must also include system-wide carbon monoxide, or CO, monitoring and control.

Most plants that burn PRB coal were not designed to deal with the fuel's propensity to ignite in bunkers, silos, and hoppers. Recognizing this, the PRB Coal Users' Group has developed a set of recommended practices for safely preventing, detecting, and extinguishing coal fires at power plants.

Safe handling and storage of PRB coal is the result of careful thought and attention to myriad details of equipment design and operation. Accidents happen when plant designers and operators discount design fundamentals or underestimate PRB coal's destructive potential.

PRB coal's environmental friendliness — and low price per BTU — come with a cost: dustiness that raises the risk of fires and explosions. Although many such incidents have not been widely publicized, they have occurred, and plant operators suggest that their frequency may be rising. Small-contained fires are reported to occur weekly at many plants, and several major explosions in recent years have caused extensive damage that cost many millions of dollars to repair.

In late 2006, the U.S. Chemical Safety and Hazard Investigation Board produced a study that found that at least 281 fires and explosions ignited by combustible dust had occurred in general industry between 1980 and 2005. Those incidents resulted in at least 119 fatalities and 718 injuries. One of the report's main findings was that secondary dust explosions, due to inadequate housekeeping and excessive dust accumulations, caused much of the damage and casualties in recent catastrophic incidents.

The PRB Coal Users' Group has developed recommended fire-prevention practices and guidelines for plants that burn PRB coal by itself or in blends. The guidelines are not equipment-specific because the physical layouts of coal-handling facilities vary significantly and because all fires are unique. The guidelines also are not comprehensive; their purpose is to recommend general practices that must be adapted for the specific needs of your plant.

The guidelines provide information about three areas: fire prevention and detection, firefighting equipment and training, and firefighting.

This article is provided by Conspec-Controls.com - A industrial gas detection company that specializes in Fixed CO Gas Monitors and PRB Coal Burning Facilities.