By Scott Trunkett and Mike Palmer

The electric power generation industry is experiencing the most complex convergence of market pressures in history. Environmental regulations are more rigorous than ever, forcing producers to make substantial capital investments in emissions conformance. At the same time, deregulation, excess capacity, and reduced market demand are driving diminishing maintenance budgets. The threat of nonconformance penalties weighs heavily against the pressure to increase profits, and the decisions between capital expenditures, potential fines, and routine equipment maintenance become a precarious balancing act.

Plant operators employ an array of methods for managing effluents and operating efficiency, including the installation of Low NOx burners, over-fired air systems, and complex soot-blowing systems. These techniques, while contributing to the effective management of undesirable pollutants, significantly increase equipment wear rates, especially in waterwalls and boiler tubing.

Until recently, most wear-susceptible boiler tubing has been protected by weld cladding methods using various nickel alloys, stainless steels, or chrome carbide composites. Infiltration brazed tungsten carbide cladding, a recent finalist for the 2003 Global Energy Awards, is an emerging boiler tube protection technology that has experienced success in highly erosive, corrosive, and abrasive environments. This cladding, recently tested by EPRI at temperatures exceeding 1000 degrees Fahrenheit, lasted longer than virtually all other materials tested; and because the unique application process creates a true metallurgical bond between cladding and tubing, this material is not subject to chipping and spalling.

This paper will discuss the results of several comprehensive laboratory analyses, as well as realworld applications of advanced wear protection, including superheater tubes, burners, and other boiler components.

By K. Scott Trunkett

Power production facilities are under ever-increasing pressure to reduce production costs to compete in a market environment that is more complex today than it’s ever been in the past. Failure to effectively reduce production costs to a competitive level means reduced profits for each MW-hr sold, and may result in reduced dispatch load—a double jeopardy in a market plagued by over capacity.

The situation is further complicated by the need for production facilities to balance costs against compliance with a growing number of stringent air quality restrictions for NOx, SOx, Mercury, and particulates. These challenges often manifest themselves in a conflicting effort to reduce day-to-day operating costs while managing offsetting capital investment and maintenance costs.

By Douglas Goebel, Michael Saari, K. Scott Trunkett, Bonnie Courtemanche P.E.

Electric power generators are experiencing the most complex confluence of market pressures in the history of the industry. Environmental regulations are stricter than ever, forcing producers to make substantial capital investments in emissions conformance, while the pressures of deregulation are making available maintenance dollars ever more scarce. The threat of non-conformance penalties weighs heavily against the pressures of Wall Street, and the decisions between capital expenditures, potential fines, and everyday equipment maintenance becomes a precarious balancing act.

The current high-cost of LNG combined with transmission bottlenecks places low NOx coalfired megawatts at a premium, particularly in those regions where generating capacity closely matches demand. This increased value of low NOx megawatts puts further pressure on personnel to maintain peak performance of their NOx management systems.

After an electric power generator invests in NOx reduction technologies to achieve conformance, it is faced with maintaining the equipment to ensure that NOx rates remain within specified tolerance. Pulverized coal traveling at high velocities through coal burners and burner tips typically produces significant component erosion, causing owners to repeatedly replace parts and even entire burner assemblies. During the period between repairs, changes in burner geometry caused by excessive erosion can impact combustion characteristics, resulting in upward trending NOx emissions.

The most advanced Low NOx burner technologies utilize a unique tungsten carbide cladding applied through an infiltration brazing process to protect components against erosion wear, substantially increasing burner life while maintaining combustion characteristics for sustained low NOx performance. This paper will discuss the exhaustive laboratory analyses used to find the best wear solution for this extreme application, how it is applied, and the performance results of these burners in actual operation after more than two years of service.

By K. Scott Trunkett

A continuing concern to operators of steam turbines is increasing operating costs. These costs reflect not only the rising cost of fuel and materials but also the decreased efficiency of the aging turbine fleet. Over time, damage to turbine components and increased steam leakage are the major factors resulting in lost efficiency. Steam leakage alone can account for as much as 80 percent of the efficiency losses in turbines.

Since the cost of fuel and materials is largely beyond the control of steam turbine operators, the primary mechanism for realizing savings is in the improvement of turbine efficiency.

An innovative program has been developed to appraise, evaluate, and restore steam turbine efficiency without major modifications to components. New turbine seal technology coupled with improved repair methods can enhance efficiency gains. This paper describes improved methods of analysis, evaluation, and repair now available to improve unit performance.