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Power Generation – Coal And Natural Gas Industry Acronyms

Power Generation – Coal And Natural Gas Industry Acronyms

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Designed for leaders across Energy & Utilities, this glossary explains operational, technical, environmental, safety, commercial, and performance terminology used in coal- and gas-fired generation. It helps executives and practitioners navigate the systems, metrics, standards, and regulations central to the Power Generation – Coal And Natural Gas Practice.

A B C D E F G H I J K L M N O P R S T U V W Z

A
ACC Air-Cooled Condenser:
A heat exchanger that condenses steam-turbine exhaust using ambient air instead of a water-cooled circulating system, reducing water consumption but making performance more sensitive to weather.
ACI Activated Carbon Injection:
An emissions-control process that injects powdered activated carbon into flue gas to capture mercury and certain other pollutants before particulate collection.
ADB Air-Dried Basis:
A coal-analysis reporting basis measured after a sample has reached approximate equilibrium with laboratory air, enabling consistent comparison of fuel properties.
AF Availability Factor:
The percentage of a reporting period during which a generating unit is capable of operating, regardless of whether it is dispatched.
AFBC Atmospheric Fluidized-Bed Combustion:
A boiler technology that burns solid fuel in a fluidized bed at approximately atmospheric pressure, supporting fuel flexibility and in-bed sulfur capture.
AFR Air-Fuel Ratio:
The ratio of combustion air to fuel, a fundamental control variable affecting efficiency, flame stability, carbon monoxide formation, and nitrogen-oxide emissions.
AFT Ash Fusion Temperature:
The temperature range over which coal ash deforms, softens, and melts, helping operators assess slagging risk and boiler fuel suitability.
AGC Automatic Generation Control:
A control function that adjusts plant output in response to system-operator signals to support frequency regulation, interchange schedules, and balancing requirements.
AIG Ammonia Injection Grid:
A network of nozzles that distributes ammonia into flue gas upstream of a selective catalytic reduction reactor, with distribution quality affecting removal efficiency and ammonia slip.
APC Air Pollution Control:
The equipment and processes used to limit particulate, sulfur, nitrogen-oxide, mercury, acid-gas, and other atmospheric emissions from generating units.
APC Auxiliary Power Consumption:
The electricity consumed by plant equipment such as pumps, fans, mills, compressors, and emissions controls, usually expressed as output or as a percentage of gross generation.
APH Air Preheater:
A heat exchanger that transfers energy from boiler flue gas to incoming combustion air, improving efficiency while influencing corrosion, fouling, and draft-system performance.
AR As-Received Basis:
A fuel-analysis basis that includes the moisture present when the sample was received, reflecting the condition in which coal is delivered and consumed.
ASME American Society of Mechanical Engineers:
A standards organization whose boiler and pressure-vessel codes and performance test codes are foundational to thermal-plant design, inspection, and acceptance testing.
A-USC Advanced Ultra-Supercritical:
A coal-fired steam-cycle class using temperatures and pressures beyond conventional ultra-supercritical designs to achieve higher efficiency, requiring advanced high-temperature materials.
AVT All-Volatile Treatment:
A steam-water chemistry regime using volatile alkalizing agents, with or without an oxygen scavenger, to control corrosion in condensate and feedwater systems.
AVR Automatic Voltage Regulator:
A generator excitation-control system that regulates terminal voltage and reactive-power behavior within equipment and grid-operating limits.
B
BACT Best Available Control Technology:
A case-specific emissions limitation applied under the U.S. Prevention of Significant Deterioration program, considering technical feasibility, environmental effects, energy impacts, and cost.
BFP Boiler Feed Pump:
A high-pressure pump that delivers feedwater through heaters and economizers to the boiler or heat-recovery steam generator.
BMCR Boiler Maximum Continuous Rating:
The maximum steam output a boiler is designed to sustain continuously under specified operating conditions.
BMS Burner Management System:
A safety control system that manages fuel admission, purging, ignition, flame monitoring, shutdown, and trip logic for boilers, duct burners, and combustion turbines.
BOP Balance of Plant:
The supporting mechanical, electrical, civil, control, fuel, water, and environmental systems outside the principal turbine, generator, or boiler package.
Btu British Thermal Unit:
A unit of heat commonly used to express fuel energy content, heat input, and plant heat-rate performance.
C
CAA Clean Air Act:
The principal U.S. federal statute governing air-quality standards, stationary-source permitting, hazardous pollutants, and power-plant emissions requirements.
CACE Conductivity After Cation Exchange:
A sensitive steam-water chemistry measurement used to detect ionic contamination that can drive corrosion, deposition, and turbine damage.
CAM Compliance Assurance Monitoring:
A U.S. regulatory framework requiring certain facilities to monitor indicators demonstrating that emissions-control equipment continues to operate properly.
CBM Condition-Based Maintenance:
A maintenance strategy that uses measured equipment condition to determine when intervention is needed rather than relying only on fixed intervals.
CC Combined Cycle:
A generating configuration that uses gas-turbine exhaust to produce steam for a steam turbine, increasing output and efficiency relative to simple-cycle operation.
CCGT Combined-Cycle Gas Turbine:
A gas-fired power plant combining one or more combustion turbines, heat-recovery steam generators, and a steam turbine.
CCR Coal Combustion Residuals:
Solid byproducts such as fly ash, bottom ash, boiler slag, and flue-gas desulfurization material that require regulated handling, storage, beneficial use, or disposal.
CEMS Continuous Emissions Monitoring System:
Instrumentation that continuously measures and records regulated stack emissions and operating parameters for compliance and performance management.
CF Capacity Factor:
Actual electricity generated during a period divided by the amount that could have been generated through continuous operation at rated capacity.
CFB Circulating Fluidized Bed:
A boiler technology that recirculates entrained solids through the combustion chamber, supporting diverse fuels, lower combustion temperatures, and in-furnace sulfur capture.
CFR Code of Federal Regulations:
The codification of U.S. federal rules, including environmental, safety, and operating requirements applicable to thermal generating facilities.
CHP Coal Handling Plant:
The systems used to receive, unload, convey, crush, sample, store, reclaim, and deliver coal to generating-unit bunkers or silos.
CHP Combined Heat and Power:
The simultaneous production of electricity and useful thermal energy from one fuel source, improving overall fuel utilization where a suitable heat load exists.
CI Combustion Inspection:
A scheduled gas-turbine maintenance scope focused on combustors, fuel nozzles, transition pieces, igniters, and associated hot-section components.
CO Carbon Monoxide:
A regulated combustion product whose concentration is used to assess combustion completeness, tuning quality, and permit compliance.
CO2 Carbon Dioxide:
The principal greenhouse gas produced by fossil-fuel combustion and a central measure for emissions inventories, reporting, and generation-efficiency initiatives.
COD Commercial Operation Date:
The contractually defined date when a generating facility has satisfied required tests and conditions and begins commercial service.
COMS Continuous Opacity Monitoring System:
An optical monitoring system that measures stack-gas opacity as an indicator of particulate emissions and air-permit compliance.
CPMS Continuous Parametric Monitoring System:
A system that continuously records operating parameters used to demonstrate proper operation of emissions-control equipment when direct pollutant measurement is not required.
CPU Condensate Polishing Unit:
Ion-exchange or filtration equipment that removes dissolved and suspended contaminants from condensate to protect boilers, steam generators, and turbines.
CSAPR Cross-State Air Pollution Rule:
A U.S. program addressing interstate transport of sulfur-dioxide and nitrogen-oxide pollution from power plants through state emission budgets and compliance obligations.
CT Combustion Turbine:
A rotary engine that converts energy from high-temperature combustion gases into shaft power for electric generation.
CTG Combustion Turbine Generator:
The integrated turbine-generator train used in simple-cycle or combined-cycle service.
CUI Corrosion Under Insulation:
External degradation hidden beneath insulation on piping and equipment, requiring risk-based inspection because it may remain undetected until leakage or failure occurs.
CWA Clean Water Act:
The principal U.S. federal statute regulating wastewater discharges, cooling-water intake structures, stormwater, and other water-related impacts.
CWP Circulating Water Pump:
A high-volume pump that moves cooling water through the condenser and cooling system, making it a major auxiliary load and reliability-critical asset.
D
DA Deaerator:
A feedwater-system vessel that uses steam heating and venting to remove dissolved oxygen and other noncondensable gases while providing feedwater storage.
DAF Dry, Ash-Free Basis:
A fuel-analysis basis that excludes moisture and ash, allowing comparison of the combustible organic portion of different coals.
DB Duct Burner:
A supplemental burner installed in a gas-turbine exhaust duct or heat-recovery steam generator to increase steam production and combined-cycle output.
DCS Distributed Control System:
The plant-wide automation platform used to monitor processes, execute control logic, manage alarms, and support operator actions.
DLE Dry Low Emissions:
A gas-turbine combustion approach that limits pollutant formation without steam or water injection, typically through premixed combustion and precise fuel-air control.
DLN Dry Low NOx:
A lean-premixed gas-turbine combustion system designed to reduce nitrogen-oxide formation without diluent injection while maintaining stable combustion.
DM Demineralized Water:
Water treated to remove dissolved ions for use as boiler makeup, cycle makeup, turbine washing, or other high-purity applications.
DO Dissolved Oxygen:
Oxygen present in plant water and steam cycles whose concentration is controlled to manage corrosion under the selected chemistry regime.
DSI Dry Sorbent Injection:
An emissions-control method that injects dry alkaline material into flue gas to reduce sulfur trioxide, sulfur dioxide, hydrogen chloride, or other acid gases.
E
EAF Equivalent Availability Factor:
The percentage of maximum generation capability available during a period after accounting for full outages and capacity deratings.
EDI Electrodeionization:
A continuous water-purification process combining ion-exchange media and an electric field, commonly used to polish reverse-osmosis permeate.
EFOR Equivalent Forced Outage Rate:
A reliability measure that combines forced outages and forced deratings to quantify the portion of time-equivalent capacity made unavailable unexpectedly.
EFORd Equivalent Forced Outage Rate Demand:
A demand-adjusted generating-unit reliability metric that measures forced unavailability during periods when the unit is needed to operate.
EGT Exhaust Gas Temperature:
The measured temperature of gas leaving a combustion turbine, used for control, performance assessment, fault detection, and hot-section protection.
EGU Electric Generating Unit:
A regulatory and operational term for equipment that converts fuel or another energy source into electricity, often defining the unit subject to specific emissions requirements.
EIA U.S. Energy Information Administration:
The federal statistical agency that collects and publishes data on generation, fuel consumption, plant characteristics, costs, capacity, and emissions.
ELG Effluent Limitations Guidelines:
U.S. national wastewater standards that establish technology-based discharge requirements for industrial categories, including steam-electric generating plants.
EOH Equivalent Operating Hours:
A gas-turbine maintenance measure that weights operating hours and duty severity to help determine inspection and overhaul intervals.
EPA U.S. Environmental Protection Agency:
The federal authority that administers major air, water, waste, and chemical regulations affecting fossil-fueled generating facilities.
EPC Engineering, Procurement, and Construction:
A project-delivery model in which one contractor assumes integrated responsibility for design, equipment and material procurement, construction, and defined performance obligations.
EPCRA Emergency Planning and Community Right-to-Know Act:
A U.S. law requiring qualifying facilities to support emergency planning and report inventories and releases of specified hazardous chemicals.
EPRI Electric Power Research Institute:
A research organization that develops technical guidance, data, tools, and collaborative programs used by power generators to improve safety, reliability, efficiency, and environmental performance.
ESP Electrostatic Precipitator:
An air-pollution-control device that electrically charges and collects fly ash and other particulate matter from flue gas.
F
FAC Flow-Accelerated Corrosion:
Wall thinning caused when flowing water or wet steam dissolves a protective oxide layer, creating a significant integrity risk in susceptible piping and components.
FBC Fluidized-Bed Combustion:
A solid-fuel combustion process in which upward-flowing air suspends fuel and bed material, promoting mixing, fuel flexibility, and lower-temperature combustion.
FD Forced Draft:
The portion of a boiler draft system that uses fans to push combustion air into the furnace and overcome upstream air-side resistance.
FFH Factored Fired Hours:
A gas-turbine maintenance measure that adjusts fired operating hours for factors such as starts, fuel, load profile, and operating severity.
FGD Flue Gas Desulfurization:
A group of wet, dry, or semi-dry processes used to remove sulfur dioxide and related acid gases from combustion exhaust.
FGR Flue Gas Recirculation:
The return of a portion of exhaust gas to the combustion zone to moderate flame temperature, control steam conditions, or reduce nitrogen-oxide formation.
FMEA Failure Modes and Effects Analysis:
A structured method for identifying potential equipment or process failures, evaluating their consequences, and prioritizing preventive controls.
FO Forced Outage:
An unplanned removal of a generating unit or major component from service because continued operation is not possible or prudent.
FOH Forced Outage Hours:
The hours during which a unit is unavailable because of an unplanned outage, used in reliability and availability reporting.
FOM Fixed Operations and Maintenance:
Plant costs that do not vary directly with electricity output, such as core staffing, recurring contracts, insurance, and routine fixed maintenance.
FOR Forced Outage Rate:
A measure of the proportion of operating and forced-outage time represented by unplanned unit unavailability.
FSFL Full-Speed Full-Load:
A turbine operating condition at rated rotational speed and full dispatched or rated load, often used as a startup milestone and performance reference.
FSNL Full-Speed No-Load:
A turbine condition at rated rotational speed before meaningful generator load is applied, commonly reached during startup and synchronization.
FSSS Furnace Safeguard Supervisory System:
A boiler safety system that enforces purge, light-off, fuel-admission, flame-proving, and master-fuel-trip sequences.
FWH Feedwater Heater:
A heat exchanger that uses turbine extraction steam to preheat feedwater, improving Rankine-cycle efficiency and managing thermal conditions.
G
GADS Generating Availability Data System:
The North American system for collecting standardized generating-unit performance, outage, derating, and event data for reliability analysis and benchmarking.
GCV Gross Calorific Value:
Fuel energy content including the heat recoverable by condensing water vapor in the combustion products, equivalent in concept to higher heating value.
GHG Greenhouse Gas:
A heat-trapping atmospheric gas, with carbon dioxide from fossil combustion forming the largest direct climate-related emission from these plants.
GMC Gross Maximum Capacity:
The maximum sustainable generator output before subtracting power consumed by station auxiliaries.
GPHR Gross Plant Heat Rate:
Fuel energy input divided by gross electrical output, used to assess conversion efficiency before deducting plant auxiliary consumption.
GSU Generator Step-Up Transformer:
The main transformer that raises generator terminal voltage to the level required for connection to the transmission system.
GT Gas Turbine:
A combustion turbine that converts the energy of compressed, heated gas into shaft power for generation or mechanical drive.
GTCC Gas Turbine Combined Cycle:
A configuration that recovers gas-turbine exhaust heat to raise steam and generate additional electricity in a steam-turbine cycle.
H
HAP Hazardous Air Pollutant:
A pollutant regulated under the U.S. Clean Air Act because of potential health or environmental effects, including mercury and certain acid gases and metals.
HAZOP Hazard and Operability Study:
A systematic team-based review that uses guide words to identify process deviations, hazards, safeguards, and operating problems.
HCl Hydrogen Chloride:
An acid gas formed from chlorine in fuel and regulated as a hazardous air pollutant for affected generating units.
HGI Hardgrove Grindability Index:
A standardized indicator of how readily coal can be pulverized, affecting mill capacity, power consumption, fineness, and maintenance.
HGP Hot Gas Path:
The gas-turbine components exposed to the highest combustion temperatures, including transition pieces, turbine nozzles, blades, and shrouds.
HHV Higher Heating Value:
Fuel energy content that includes the latent heat recovered if combustion water vapor is condensed, commonly used in North American heat-rate reporting.
HMI Human-Machine Interface:
The operator-facing displays and controls used to monitor plant status, manage alarms, issue commands, and interpret process conditions.
HP High Pressure:
The highest-pressure section of a steam cycle or turbine train, requiring careful control of temperature, chemistry, stress, and component condition.
HRH Hot Reheat:
Steam leaving the reheater on its way to an intermediate-pressure turbine section, with temperature control important to efficiency and component life.
HRSG Heat Recovery Steam Generator:
Equipment that captures gas-turbine exhaust heat to generate steam for a combined-cycle steam turbine or process use.
I
I&C Instrumentation and Control:
The sensors, analyzers, control systems, logic, actuators, and communications used to operate and protect plant processes.
IAPWS International Association for the Properties of Water and Steam:
The organization that develops internationally recognized formulations and technical guidance for water, steam, and cycle chemistry.
IBD Intermittent Blowdown:
Periodic removal of boiler water from low points to discharge settled solids and control accumulated contaminants.
ID Induced Draft:
The portion of a boiler draft system that uses fans to pull flue gas through the furnace and downstream emissions-control equipment.
IGCC Integrated Gasification Combined Cycle:
A plant configuration that converts coal or another feedstock into synthesis gas, cleans it, and uses it in a combined-cycle generating system.
IGV Inlet Guide Vane:
An adjustable compressor component that controls airflow, startup behavior, part-load performance, and exhaust conditions in a gas turbine.
IM Inherent Moisture:
Moisture held within a coal particle’s pore structure, influencing reported heating value, handling behavior, and pulverizer performance.
IP Intermediate Pressure:
The middle-pressure section of a multi-casing steam turbine or associated steam system, typically receiving reheated steam.
IPB Isolated-Phase Bus:
A high-current bus system in which each electrical phase is enclosed separately, commonly connecting a large generator to its main and auxiliary transformers.
ISO International Organization for Standardization:
The international standards body whose reference conditions and management standards support equipment ratings, testing, quality, and environmental programs.
J
JSA Job Safety Analysis:
A task-level review that breaks work into steps, identifies hazards, and specifies controls before maintenance or operating work begins.
K
KKS Kraftwerk-Kennzeichensystem:
A structured power-plant identification system used to code facilities, systems, equipment, and components consistently across engineering and asset documentation.
L
LAER Lowest Achievable Emission Rate:
A stringent U.S. emissions standard applied to major new or modified sources in areas that do not meet applicable ambient air-quality standards.
LCI Load-Commutated Inverter:
A power-electronics system commonly used as a static starter to accelerate large gas turbines through the generator before ignition and self-sustaining operation.
LCOE Levelized Cost of Energy:
The discounted lifetime cost of building and operating a generating asset divided by its discounted electricity production, enabling comparisons across options and scenarios.
LDAR Leak Detection and Repair:
A structured program for finding and correcting fugitive emissions from valves, connectors, seals, and other regulated equipment components.
LEL Lower Explosive Limit:
The minimum concentration of a combustible gas or vapor in air that can support flame propagation, central to gas detection and ventilation controls.
LHV Lower Heating Value:
Fuel energy content that excludes recovery of the latent heat in combustion water vapor, often used for gas-turbine efficiency reporting outside North America.
LNB Low-NOx Burner:
A burner designed to limit nitrogen-oxide formation by controlling fuel-air mixing, flame temperature, and combustion staging.
LOI Loss on Ignition:
The mass lost when an ash sample is heated under specified conditions, commonly used as an indicator of unburned carbon and combustion completeness.
LOTO Lockout/Tagout:
A hazardous-energy-control procedure that isolates, locks, verifies, and identifies energy sources before servicing or maintenance.
LP Low Pressure:
The lowest-pressure steam-cycle or turbine section, where moisture control, condenser vacuum, exhaust losses, and last-stage-blade condition are important.
LTSA Long-Term Service Agreement:
A multiyear contract covering defined maintenance, parts, field services, repairs, or performance commitments for major plant equipment, especially gas turbines.
M
MACT Maximum Achievable Control Technology:
A U.S. emissions-control standard for hazardous air pollutants based on the performance of leading sources within a regulated category.
MATS Mercury and Air Toxics Standards:
U.S. federal standards limiting mercury, acid gases, and toxic non-mercury metals from coal- and oil-fired electric generating units.
MCC Motor Control Center:
An electrical assembly containing motor starters, protection, controls, and distribution equipment for groups of plant motors.
MCR Main Control Room:
The central staffed location from which operators monitor, control, coordinate, and respond to plant and unit conditions.
MCR Maximum Continuous Rating:
The highest output equipment is designed to sustain continuously under specified conditions without exceeding operating limits.
MFT Master Fuel Trip:
A protective action that rapidly shuts off all fuel to a boiler or combustion system when unsafe conditions or critical equipment failures occur.
MMBtu Million British Thermal Units:
A standard unit used for natural-gas pricing, fuel consumption, thermal input, and variable generation-cost calculations.
MPC Model Predictive Control:
An advanced control method that uses a process model to optimize future control actions while respecting operating, emissions, and equipment constraints.
MTBF Mean Time Between Failures:
A reliability measure representing average operating time between repairable equipment failures.
MTTR Mean Time to Repair:
A maintainability measure representing the average time required to diagnose, repair, test, and return failed equipment to service.
MW Megawatt:
A unit of power equal to one million watts, commonly used to express instantaneous plant, unit, or equipment output.
MWe Megawatt Electric:
A unit used to distinguish electrical output from thermal energy input or heat output.
MWh Megawatt-Hour:
A unit of electrical energy equal to one megawatt produced or consumed for one hour.
MWth Megawatt Thermal:
A unit of thermal power used to distinguish heat input or useful heat output from electrical generation.
N
NAAQS National Ambient Air Quality Standards:
U.S. health- and welfare-based limits for specified outdoor pollutants that shape plant permitting, modeling, controls, and operating restrictions.
NBIC National Board Inspection Code:
A recognized code governing installation, inspection, repair, and alteration of boilers, pressure vessels, and pressure-retaining items.
NCF Net Capacity Factor:
Net electricity generated during a period divided by the net generation possible through continuous operation at rated net capacity.
NCV Net Calorific Value:
Fuel energy content excluding latent heat recovery from water vapor, equivalent in concept to lower heating value.
NDE Nondestructive Examination:
Inspection methods used to assess materials, welds, and components without impairing their future serviceability.
NDT Nondestructive Testing:
Testing techniques such as ultrasonic, radiographic, magnetic-particle, and liquid-penetrant methods used to detect defects without damaging the item examined.
NERC North American Electric Reliability Corporation:
The organization that develops and enforces mandatory reliability standards and administers generating-performance data programs for the bulk power system.
NESHAP National Emission Standards for Hazardous Air Pollutants:
U.S. federal requirements that limit hazardous air pollutants from designated source categories using specified control and work-practice standards.
NFPA National Fire Protection Association:
A standards organization whose codes address boilers, combustion systems, fuel handling, electrical safety, fire protection, and related plant hazards.
NGCC Natural Gas Combined Cycle:
A gas-fired configuration that combines combustion-turbine generation with steam generation from recovered exhaust heat.
NMC Net Maximum Capacity:
The maximum sustainable electrical output available for export after subtracting plant auxiliary loads.
NOx Nitrogen Oxides:
Combustion-related air pollutants regulated because they contribute to ozone, particulate formation, and other adverse environmental effects.
NPHR Net Plant Heat Rate:
Fuel energy input divided by net electrical output, making it a primary measure of plant efficiency and fuel-cost performance.
NPSH Net Positive Suction Head:
The pressure margin at a pump inlet above the liquid’s vapor pressure, used to prevent cavitation and related performance or damage problems.
NSPS New Source Performance Standards:
U.S. federal emissions standards for specified categories of new, modified, or reconstructed stationary sources.
NSR New Source Review:
A U.S. preconstruction air-permitting program for new facilities and major modifications, incorporating emissions-control and air-quality analyses.
O
O&M Operations and Maintenance:
The activities, personnel, processes, and expenditures required to operate generating assets safely and maintain reliability, compliance, and performance.
OCGT Open-Cycle Gas Turbine:
A gas-turbine plant that exhausts combustion gases without using them in a steam bottoming cycle, enabling fast starts but generally lower efficiency.
OEM Original Equipment Manufacturer:
The company that originally designs and supplies major equipment and often provides parts, technical guidance, repairs, upgrades, and long-term service.
OFA Overfire Air:
Combustion air introduced above the main burner zone to stage combustion and reduce nitrogen-oxide formation while completing fuel burnout.
OSHA Occupational Safety and Health Administration:
The U.S. federal agency that establishes and enforces workplace safety and health requirements applicable to plant operations, maintenance, and construction.
OT Oxygenated Treatment:
A steam-water chemistry regime that maintains controlled oxygen in high-purity feedwater to promote protective oxide formation in suitable systems.
OTSG Once-Through Steam Generator:
A steam generator in which water passes continuously through heating surfaces without a conventional steam drum, supporting compact designs and flexible operation.
P
P&ID Piping and Instrumentation Diagram:
An engineering drawing showing process equipment, piping, valves, instruments, control loops, and protective functions used for design, operations, and maintenance.
PA Primary Air:
Air used in pulverized-coal systems to dry and convey fuel from mills to burners and to support initial combustion.
PAUT Phased Array Ultrasonic Testing:
An advanced inspection method that electronically steers ultrasonic beams to detect and characterize flaws in welds and pressure-retaining components.
PC Pulverized Coal:
Coal ground to a fine powder and pneumatically conveyed to burners, enabling rapid and controlled combustion in utility boilers.
PdM Predictive Maintenance:
A strategy that uses trends, diagnostics, and predictive models to forecast equipment degradation and schedule work before functional failure.
PHA Process Hazard Analysis:
A systematic assessment of process hazards, failure scenarios, consequences, safeguards, and risk-reduction needs for covered systems.
PLC Programmable Logic Controller:
An industrial controller used for deterministic equipment sequencing, interlocks, local automation, and protective logic.
PLF Plant Load Factor:
Average plant output over a period divided by maximum or rated output, commonly used internationally as a utilization indicator.
PM Particulate Matter:
Airborne solid and liquid particles in flue gas that are controlled through devices such as electrostatic precipitators, fabric filters, and wet scrubbers.
PM Preventive Maintenance:
Planned work performed at defined intervals to reduce failure probability and preserve equipment function, safety, and reliability.
PM10 Particulate Matter with a Diameter of 10 Micrometers or Less:
A regulated particle-size category considered in emissions testing, air-quality modeling, permitting, and control-system performance.
PM2.5 Particulate Matter with a Diameter of 2.5 Micrometers or Less:
A fine-particle category with important health and regulatory implications, including direct emissions and particles formed from sulfur and nitrogen compounds.
POF Planned Outage Factor:
The proportion of period hours represented by scheduled unit unavailability for inspections, overhauls, repairs, or major projects.
POH Planned Outage Hours:
The scheduled hours during which a unit is unavailable for planned maintenance, inspections, modifications, or other approved work.
PPA Power Purchase Agreement:
A contract defining the sale of electricity, capacity, or associated products, including pricing, delivery, availability, testing, and performance obligations.
PRB Powder River Basin:
A major U.S. coal-producing region known for relatively low-sulfur subbituminous coal with distinctive moisture, heating-value, handling, and combustion characteristics.
PRDS Pressure-Reducing and Desuperheating Station:
A valve and spray-water arrangement that reduces steam pressure and temperature for auxiliary, process, startup, or bypass service.
PSD Prevention of Significant Deterioration:
A U.S. air-permitting program for major new or modified sources in areas meeting applicable ambient air-quality standards.
PSM Process Safety Management:
A regulatory and management framework for controlling catastrophic hazards associated with covered quantities of highly hazardous chemicals.
PSS Power System Stabilizer:
A generator excitation-control function that adds damping to electromechanical oscillations and supports stable interconnected operation.
PTC Performance Test Code:
A standardized procedure, particularly from the American Society of Mechanical Engineers, for testing boilers, turbines, and complete plants with defined accuracy and uncertainty.
PTW Permit to Work:
A formal authorization process that defines work scope, hazards, isolations, precautions, responsibilities, and validity before specified tasks proceed.
R
RATA Relative Accuracy Test Audit:
A prescribed comparison of a continuous emissions monitor against an approved reference method to verify regulatory measurement accuracy.
RCA Root Cause Analysis:
A structured investigation that identifies the underlying technical and organizational causes of an event and establishes actions to prevent recurrence.
RCM Reliability-Centered Maintenance:
A methodology that selects maintenance tasks by analyzing asset functions, failure modes, consequences, and the effectiveness of available interventions.
RCRA Resource Conservation and Recovery Act:
The principal U.S. federal law governing solid and hazardous waste management, including requirements affecting coal-combustion residuals.
RH Reheater:
Boiler or steam-generator heat-transfer surfaces that raise the temperature of partially expanded steam before it returns to a later turbine section.
RLA Remaining Life Assessment:
An engineering evaluation of degradation, operating history, inspection findings, and material condition to estimate safe future service and required interventions.
RO Reverse Osmosis:
A membrane process that removes dissolved salts and other contaminants from makeup water or wastewater under applied pressure.
RTD Resistance Temperature Detector:
A temperature sensor whose electrical resistance varies predictably with temperature, widely used in bearings, windings, fluids, and process equipment.
RUL Remaining Useful Life:
An estimate of the operating time or cycles an asset can provide before reaching a defined failure, inspection, or replacement threshold.
S
SAT Station Auxiliary Transformer:
A transformer that supplies plant auxiliary systems from an external or station source, particularly during startup, shutdown, or loss of normal unit supply.
SC Supercritical:
A steam-cycle design operating above water’s critical pressure, eliminating distinct boiling in the furnace circuit and enabling higher efficiency than conventional subcritical units.
SCADA Supervisory Control and Data Acquisition:
A system for remote monitoring, data collection, alarming, and supervisory control of plant and offsite equipment.
SCGT Simple-Cycle Gas Turbine:
A gas-turbine generating configuration without a steam bottoming cycle, valued for rapid startup and operational flexibility.
SCR Selective Catalytic Reduction:
An emissions-control process that reacts ammonia with nitrogen oxides over a catalyst to form nitrogen and water.
SFC Specific Fuel Consumption:
The quantity of fuel consumed per unit of electrical output, used as an efficiency and operating-cost metric.
SFC Static Frequency Converter:
A power-electronics system that supplies controlled-frequency power to accelerate a gas-turbine generator during startup.
SH Superheater:
Boiler or steam-generator heat-transfer surfaces that raise saturated steam above its saturation temperature before turbine admission.
SIL Safety Integrity Level:
A discrete measure of risk-reduction performance required from a safety instrumented function, determined through hazard and risk analysis.
SIP State Implementation Plan:
A U.S. state’s enforceable plan for attaining and maintaining federal ambient air-quality standards, including source-specific requirements and permitting rules.
SIS Safety Instrumented System:
An independent arrangement of sensors, logic solvers, and final elements that moves a process to a safe state when defined hazardous conditions occur.
SNCR Selective Non-Catalytic Reduction:
A nitrogen-oxide control process that injects ammonia or urea into a suitable high-temperature flue-gas region without using a catalyst.
SO2 Sulfur Dioxide:
A regulated combustion pollutant formed from sulfur in fuel and controlled through fuel selection, sorbent injection, or flue-gas desulfurization.
SO3 Sulfur Trioxide:
A sulfur oxide that can form sulfuric-acid mist, contribute to visible plume and corrosion, and affect air-preheater and particulate-control performance.
SOFA Separated Overfire Air:
Combustion air introduced through ports separated from the main burner zone to provide deeper staging and reduce nitrogen-oxide formation.
SOH Scheduled Outage Hours:
Hours of unit unavailability associated with outages arranged in advance, including planned maintenance and scheduled corrective work.
SOx Sulfur Oxides:
A collective term for sulfur-containing combustion gases, principally sulfur dioxide and sulfur trioxide, that drive emissions-control and corrosion concerns.
SPCC Spill Prevention, Control, and Countermeasure:
A U.S. regulatory program requiring qualifying facilities to plan for and prevent oil discharges to navigable waters and adjoining shorelines.
ST Steam Turbine:
A rotating machine that converts the thermal and pressure energy of steam into shaft power for electricity generation.
STG Steam Turbine Generator:
The integrated steam-turbine and electrical-generator train used in coal-fired and combined-cycle plants.
STIG Steam-Injected Gas Turbine:
A gas-turbine configuration that injects steam into the combustor or flow path to increase output and, in some applications, reduce emissions.
SWFGD Seawater Flue Gas Desulfurization:
A sulfur-dioxide removal process that uses the natural alkalinity of seawater, principally at coastal generating sites.
T
TBC Thermal Barrier Coating:
A heat-resistant coating applied to gas-turbine hot-section components to reduce metal temperature and support higher firing temperatures and component life.
TDLAS Tunable Diode Laser Absorption Spectroscopy:
An optical measurement technique used for fast, selective monitoring of combustion and flue-gas constituents such as oxygen, carbon monoxide, and ammonia.
TDS Total Dissolved Solids:
The combined concentration of dissolved substances in water, monitored to control scaling, corrosion, blowdown, and treatment-system performance.
TET Turbine Exhaust Temperature:
The temperature of gas leaving a combustion turbine, which influences control limits, heat-recovery performance, and diagnostic assessment.
TIT Turbine Inlet Temperature:
The gas temperature entering a turbine section, a key determinant of output and efficiency that is often inferred rather than measured directly.
TM Total Moisture:
The full moisture content of coal, including surface and inherent moisture, which affects delivered energy, handling, pulverization, and boiler performance.
TMCR Turbine Maximum Continuous Rating:
The maximum output a turbine is designed to sustain continuously at specified steam or gas conditions.
TMDL Total Maximum Daily Load:
A regulatory calculation of the maximum pollutant load a water body can receive while meeting water-quality standards, potentially constraining plant discharges.
TOC Total Organic Carbon:
A measure of organic contamination in water used to assess treatment performance, cycle purity, and wastewater characteristics.
TOFD Time-of-Flight Diffraction:
An ultrasonic inspection method that uses diffracted signals to detect and size flaws in welds and pressure-retaining components.
TRIR Total Recordable Incident Rate:
A standardized occupational-safety metric expressing recordable cases per 200,000 work hours for workforce and contractor performance monitoring.
TSI Turbine Supervisory Instrumentation:
Instrumentation that monitors critical turbine conditions such as vibration, speed, eccentricity, differential expansion, axial position, and casing expansion.
TSS Total Suspended Solids:
The concentration of particles suspended in water, commonly monitored in plant wastewater, ash-handling streams, and permitted discharges.
U
UAT Unit Auxiliary Transformer:
A transformer that supplies a generating unit’s auxiliary loads from the generator during normal operation.
UBC Unburned Carbon:
Carbon remaining in ash after combustion, indicating incomplete burnout and potentially reducing efficiency and ash marketability.
UEL Upper Explosive Limit:
The highest concentration of a combustible gas or vapor in air that can sustain flame propagation under specified conditions.
USC Ultra-Supercritical:
A high-temperature, high-pressure steam-cycle class that improves coal-plant efficiency and lowers fuel use and emissions per unit of output relative to subcritical designs.
UT Ultrasonic Testing:
A nondestructive inspection method using high-frequency sound waves to measure thickness and detect internal discontinuities in materials and welds.
V
VFD Variable-Frequency Drive:
A motor-control device that varies electrical frequency and voltage to regulate speed, reduce throttling losses, and improve process control.
VGV Variable Guide Vane:
An adjustable turbomachinery vane used to manage airflow, compressor stability, efficiency, and operating range.
VM Volatile Matter:
The portion of coal released as gases and vapors during standardized heating, influencing ignition, flame behavior, and combustion-system design.
VOC Volatile Organic Compound:
An organic substance that readily enters the atmosphere and may be regulated because it contributes to ground-level ozone or presents hazardous-air-pollutant concerns.
VOM Variable Operations and Maintenance:
Operating and maintenance costs that change with plant output, run hours, starts, or fuel throughput.
VWO Valves Wide Open:
A steam-turbine operating condition with control valves fully open, used to define maximum-flow capability and certain performance guarantees.
W
WESP Wet Electrostatic Precipitator:
An electrically charged collection device using wet surfaces to capture fine particulate, sulfuric-acid mist, and other difficult-to-control aerosols.
WFGD Wet Flue Gas Desulfurization:
A scrubber process that contacts flue gas with an aqueous alkaline slurry or solution to remove sulfur dioxide and other acid gases.
WHRU Waste Heat Recovery Unit:
Equipment that captures otherwise rejected heat from exhaust or process streams for steam production, water heating, or other useful duties.
WI Wobbe Index:
A measure combining fuel heating value and relative density to indicate the interchangeability and heat-input behavior of gaseous fuels through a fixed orifice.
WTP Water Treatment Plant:
Onsite systems that condition raw water and produce the quality required for boiler makeup, cooling, service, potable, or other plant uses.
Z
ZLD Zero Liquid Discharge:
A wastewater-management approach that eliminates routine liquid discharge by maximizing water recovery and converting remaining contaminants into concentrated brine or solids.