O&M

Four concrete cooling towers at a coal-fired electrical generation plant exhibited reinforcing steel corrosion that was causing concrete deterioration. This case study follows the repairs to those towers—how the corrosion control solution was selected, how repairs were made, and how follow-up tests found the repairs to be effective three years later.

Since 1972, titanium-tubed power plant surface condensers have been providing corrosion-free service. Recent process advances are making the material suitable for even more applications.

In today’s solid-fueled power plant, managing emissions and moving materials more defines the task than the traditional work of making megawatts. That’s the message that emerged from the coal and solid fuels track at this year’s ELECTRIC POWER.

Radial, axial, and circumferential metallic seals installed on rotary, regenerative air preheaters have evolved little from the original metal strip designs that date back to the original Ljungström preheaters developed nearly a century ago. Unfortunately, metallic strip seals degrade soon after installation, allowing excessive air-to-gas leakage, which translates into increased fuel consumption and fan power.

Neural networks have already found practical application in many plants, and recent advancements in artificial intelligence promise to shape the design of the next generation of power plant supervisory controls. Will future plant operators be fashioned from silicon?

The international policy framework regulating the emissions of greenhouse gases from industrial and utility boilers is in flux. Meanwhile, most boiler owners are evaluating potential strategies for when, not if, more stringent emissions reduction regulations are put in place. One of the most attractive compliance options is the cofiring of biomass in existing coal-fired boilers.

Many large utility-scale units with copper alloy condensers and feedwater heaters lose generating capacity when copper and copper oxide deposits develop on high-pressure (HP) steam turbine blading. It is not unusual for a 400-MW unit to lose 10% of its generating capacity over a six-month period when water treatment processes aren’t properly tuned to prevent copper transport in the steam and condensate systems. In fact, one utility reported that it lost 20 MW of capacity in one month because of such deposits. The financial implications of such deposits, particularly in power markets where plants are pushed to their generating limits, are tremendous.

This series of articles focuses on the nuts and bolts of predictive maintenance (PdM), also known as condition-based maintenance. A well-defined and well-executed PdM program saves time and money by reducing unneeded time-based maintenance tasks and by identifying and fixing problems before they cause equipment failure or plant shutdown. In this article, we begin introducing condition-monitoring techniques commonly in use at power plants.

Fire protection systems for air-cooled hydroelectric generators have several special requirements due to these generators’ unique geometries. This survey of options will help plant owners and operators make the best equipment selections for their plants and thereby avoid unexpected surprises.

One of the largest returns on investment a plant can achieve is the improved condenser performance that results from an effective condenser tube cleaning. Perhaps it is time to reevaluate your choice of cleaning technologies, establish an optimal cleaning schedule, and add routine air and water in-leakage surveys to your plant’s maintenance schedule.

Because refractory is out of sight inside the gas flow path of a steam generator and its auxiliaries, it’s also often out of mind. That is, until the refractory fails and causes a forced outage.

Efficient boiler operation requires boiler auxiliary equipment to operate in harmony. In this third and last installment of our Power 101 series, we examine ways to decrease the auxiliary power requirements of boiler auxiliaries.

This year’s series will focus on predictive maintenance (PdM), also known as condition-based maintenance.

Imagine this scenario: Two separate power plants experience a bowing problem greater than 18 mils with a steam-turbine rotor. The turbines are from the same manufacturer and several repair options are reviewed. Management at both plants selects an innovative approach involving removal of a substantial amount of material, which is replaced with weld overlay and then machined to correct diameters and centerline of the balance piston area. One plant’s insurance company covers the repair, the other plant’s doesn’t. Why?

Thule (“Two Lee”) Air Base is a 254–square mile base located in a coastal valley in the northwestern corner of Greenland, within the Arctic Circle. The base, the U.S.’s northernmost military installation, is nestled between mountains and surrounded by icebergs and glaciers as far as the eye can see.

Beginning each spring and continuing through the fall, backpressure readings at Rosebud Operating Services Inc. indicated substantial drops in the condenser’s efficiency. Increased backpressure results in higher net plant heat rate and a corresponding measurable decrease in power generation.

On January 27, the U.S. Chemical Safety Board (CSB) released a case study examining the causes of a heat exchanger rupture and ammonia release at the Goodyear Tire and Rubber Plant in Houston in 2008. Use these lessons learned to check your employee tracking system and to determine whether your plant has installed valves that […]

In operation since 2000, TECO Energy Inc.’s 132-MW San José Power Station was the first coal-fired power plant built in Central America and is still the largest one. Used as a baseload plant, the facility successfully combines high availability with a business model that promotes sustainable environmental practices and a safe workplace.

Steam turbines convert the thermal energy in motive steam to rotating mechanical energy, and the generator converts that energy into electrical power. One important requirement for safe and reliable operation is preventing water induction in the steam turbine and avoiding water hammer in the steam piping system. ASME standards present the design guidelines for removing moisture from steam lines; this article explains a practical design process.

If your facility has recently seen an upsurge in bearing failures on boiler feedwater (BFW) pumps, you are not the only plant experiencing these unnecessary and costly failures. The failure causes are often elusive, which is why plants have so many unresolved repeat failures.

Efficient boiler operation requires boiler auxiliary equipment to operate in harmony. The air preheater, for example, though it has few moving parts, is vital to maintaining efficient boiler performance. In this second installment of our Power 101 series, we examine performance degradation caused by corrosion and fouling of the air preheater that results from the combustion of coal plus the effects of ammonia and sodium bisulfite injection for SO₃ mitigation.

Designing large package boilers rated at over 400,000 lb/h steam production is a challenge because of shipping limitations within the U.S. and Canada.

San Miguel Electric Cooperative selected and installed an automatic sootblowing system for its Unit 1 to minimize clinkers in the boiler that caused semi-annual unscheduled outages. New boiler surface-cleaning equipment and intelligent cleaning software eliminated these expensive outages.

At Morgantown Generating Station, plant personnel used innovative methods to combine model predictive control with distributed control system–based process control algorithms to improve waterwall temperature control and main steam temperature control and to enhance unit ramp rate capability. The previous heat rate and NO_x optimization performance gains were retained. Focusing beyond basic loops of feedwater, air, and O₂, the project considered issues such as PID controller override configuration and limitations. The techniques used to overcome these challenges improved unit ramp rate capability beyond any previous unit performance.

An unintended consequence of employing selective catalytic reduction and wet flue gas desulfurization to reduce nitrogen oxide and sulfur dioxide levels at coal-fired power plants has been unwanted sulfur trioxide (SO₃) emissions. Picking the right sorbent in the right amount can eliminate that problem.

The Electric Power Research Institute has developed a pair of diagnostic tools that combine and integrate features from multiple sources of plant information. The Diagnostic Advisor and the Asset Fault Signature Database will improve diagnostics for and troubleshooting of equipment faults by providing a holistic view of the condition of plant equipment.

In all of these cases, frequent oil analysis monitoring and preestablished action plans were able to allow for transformer replacement before the occurrence of a catastrophic failure. Exelon’s experience, as well as that of other power utilities across the grid, has spawned a report by the Institute of Nuclear Power Operations (INPO) of Atlanta, Georgia, that recommends that performance monitoring and trending be applied to all large transformers in order to establish a baseline for transformer maintenance strategies.

Sudden bumps and shocks are great fun when you are off-roading or are riding on a rollercoaster. But when you are operating a piece of equipment, you want it to be running as smoothly as a Cadillac rolling down the interstate. Sudden changes in pressure produce vibration, cavitation, and water hammer and generally lower the lifespan and reliability of fluid systems.

The Electric Power Research Institute (EPRI) has identified four breakthrough technologies and funded them through its Strategic Research and Development Portfolio. EPRI expects to accelerate development of these innovations because they are likely to have significant effects on how electricity is generated and delivered.

The quality of the cooling water intake and the amount of debris in that water affects the operation and performance of the condenser and therefore the thermal performance of the typical steam plant.