Dominion Generation (DG) has installed selective catalytic reduction (SCR) systems on many of the large coal-fired generating units it operates. The catalyst used has an SO2 to SO3 oxidation rate of about 1%, which roughly doubles the SO3 concentration at the outlet of the boiler economizers. The magnitude of the increase was proportional to the […]
Flyash and condensed sulfur trioxide (SO3) are the major components of flue gas that contribute to the opacity of a coal plant’s stack emissions (stack opacity). Estimates are that 75% to 85% of bituminous coal-fired plants with selective catalytic reduction (SCR) and/or wet flue gas desulfurization (FGD) systems are likely to produce enough SO3 vapor […]
Carbon capture and sequestration (CCS) have elbowed their way into the nation’s lexicon with the rise in concern over climate change. But few of the journalists who are hyping global warming have taken the trouble to learn the ins and outs of producing affordable electricity from coal. Citizens of the industrialized world now wring their […]
As gencos seek to improve plant reliability and availability, many are turning to on-line condition monitoring for help. Huge advances in the capabilities of on-line diagnostics have occurred over the past five years. By using this technology, plant personnel can spot early warning signs of impending equipment failure and take action to correct the underlying […]
Part I of this three-part series (POWER, October 2006) explored the negative impacts of sulfur trioxide (SO3) on the operation and maintenance of back-end plant equipment. In this issue, we list and quantify the likely and potential benefits of limiting the concentration of SO3 in flue gas to 3 ppm at the entrance to the air heater. Part III—to appear in the April 2007 issue—will describe the characteristics of an optimal SO3 removal technology and present the technical details and operating experience of one patented process that has worked successfully at a half-dozen plants for up to three years.
The welds on superheater and reheater headers are arguably the most stressed parts of a modern steam plant. For that reason, it’s surprising that they also may be the most under-inspected. Cracks are rare, but they can be repaired if found early. One plant avoided a long forced outage to replace a reheater outlet header by using the correct condition assessments and welding techniques.
A systematic, performance-driven maintenance program for optimizing combustion can achieve great results. The challenge for an O&M staff is deciding which proven strategy and tactics for reducing NOx and improving plant reliability to adapt and implement. The structured approach presented here has proven its worth at several plants that have wrestled with problems similar to yours.
The compliance clock is ticking / First-class maintenance in a developing country / Bypass losses squander big bucks / Revised operating procedures
Mandatory standards advance / To drain or not to drain / Practical aspects of burning landfill gas / Time management
Safety issues related to the use of gaseous chlorine for disinfecting cooling water are pushing plant operators to examine other alternatives. Two units of Cardinal Generating Station recently switched to a liquid chlorination system, with pumpless vacuum injection, that was easy to install and has proven reliable. That switch has resulted in one less safety headache for the operations staff and one less invitation to regulatory scrutiny.