The following is a list of common definitions related to power generation.
The following is a list of common definitions related to power generation.
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Abatement | Effort to avoid emission of carbon dioxide Undertaking abatement activities on a power plant would serve to reduce its carbon intensity. | Carbon intensity |
| AGC | Automatic generation control Used by the system operators to control the output of generators connected to the electricity network | Governor (device) |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Bagasse | Waste plant fibre left after the juices have been removed from sugar cane by crushing. Burning bagasse in boilers at sugar mills is a common form of renewable energy using biomass. | Biomass |
| Bag filter | A casing containing thousands of long cloth bags used to remove fly ash from flue gas. The bags are back-flushed using compressed air. | Precipitator |
| Barring | The process of slowly turning the turbine-generator shaft to prevent bowing while it is still hot after shutdown Typically, barring is achieved using turning gear, a small electric motor and gearbox connected to the generator shaft. Early in the history of power plants, barring was done by operators turning the shaft with a bar. This is still done if electric barring is not available, as the consequences of bowing a shaft are enormous. | Turning gear |
| Biomass | Living or recently dead material such as plant matter, used as either fuel or industrial production as biofuel It is a renewable resource obtained from several different plants, for example wood waste, sugar cane, corn, hemp and others. | Biofuel |
| Black start | Starting a unit without external power supply from the electricity network In the context of an electricity market, that capability of completing a black start is known as system restart ancillary service (SRAS). Black start capability is typically provided by a local gas turbine, generating sufficient electrical power to drive pumps and fans on only one unit in the power station until it comes online. Once that unit is up, it can provide auxiliary power to the others at the same location, or feed into the grid again. A black start does not require a synchronising step as the network is down, but subsequent generators coming online will need to synchronise. | Ancillary services |
| Blade | In a reaction turbine, the blade is the main moving part attached to the turbine shaft It extracts the pressure and heat energy from the steam and converts it to rotating mechanical energy by turning the shaft. | Reaction turbine |
| Bled steam | Steam extracted from the turbine to provide heat to the feedwater heaters Note that the deaerator is also a feedwater heater – it also receives bled steam from the turbine, but the steam is mixed with and heats the water instead of transferring heat through a shell and tube heat exchanger. | LP heater, HP heater, deaerator, auxiliary steam |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| CAES | Compressed air energy storage | Grid energy storage |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| DAF | Dry ash free An analysis of coal based on removal of water and ash from the coal sample |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| EAF | Equivalent availability factor Calculation of availability based on unit outages and load reductions | EFOR, KPI, availability |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| FCAS | Frequency control ancillary service, ramp rate regulation |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Gasification | A chemical process that converts a solid fuel into gases. Where the gasification is carried out immediately prior to combustion in a combined cycle gas turbine, this configuration is known as IGCC. Gasification of coal may also be carried out underground, as in UCG. Finally, some gasification plants target synthetic oils as the end products, in gas to liquid. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Heat rate | The amount of fuel energy required to produce electrical energy Heat rate is the inverse of efficiency, incorporating a factor of 3600 due to the differing units of fuel energy (kJ) and electrical energy (kWh) – there are 3600 kJ in 1 kWh. | Efficiency |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Ionisation | Heating the atoms or molecules of a gas so that the electrons dissociate from the nuclei. By this means a gas transitions into the plasma phase. Transition between the liquid and gas phases is called evaporation and condensation. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Joule–Thomson effect | The phenomenon where a gas or liquid changes temperature when it experiences a pressure drop If this pressure drop occurs as the gas passes through a valve or other restriction, this would be called a throttling process. The effect is applied in air conditioning and refrigeration equipment, which incorporates a thermal expansion (TX) valve. | Thermal expansion valve |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Kyoto Protocol | An international agreement made in 1997 that sets emissions reduction targets for developed countries and establishes mechanisms to reduce the emissions of developing countries The Kyoto Protocol is an addendum to the United Nations Framework Convention on Climate Change. The protocol includes the Clean Development Mechanism (CDM), designed to encourage energy-efficiency initiatives in developing countries. The Certified Emission Reduction (CER) process validates the effect of the initiatives. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Labyrinth seal | Strips and grooves on a shaft that provide a torturous path for sealing steam Used in sealing of steam on turbine shafts, and sealing of oil and hydrogen on generator shafts. | Gland seal |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Mollier chart | Enthalpy–enthalpy diagram, showing the enthalpy on the vertical axis, and the entropy on the horizontal axis This chart is useful for calculating the turbine isentropic efficiency, as a vertical line represents expansion at constant entropy, and the height of the line is the enthalpy drop. Also known as h-s diagram. | T-s chart |
| Max cap | Maximum capacity One of three modes describing the configuration of the unit around full load |
|
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Natural draft | A cooling tower design that uses natural convection currents of hot air to draw air into the tower to cool the water Typically, natural draft cooling towers are constructed as hyperboloid lattice steel and concrete. The shape is for structure not airflow. | Mechanical draft |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| OCGT | Open-cycle gas turbine A simple configuration of gas turbine including a compressor, combustion chambers and turbine The open-cycle gas turbine uses the Brayton cycle. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| PA | Primary air This term typically applies to fans, that is, primary air fans supply air to the pulverisers to carry pulverised fuel from the pulveriser to the burners. The term also applies to ductwork relating to the primary air system, for example hot and cold primary air ducts and dampers lead to the pulverisers. | * |
| Term | Explanation and discussion | References and related terms |
|---|
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Rankine cycle | The thermodynamic cycle used by most boiler–turbine generating units This cycle includes addition of heat in the boiler, extraction of energy through expansion of steam in the turbine, and rejection of heat using the condenser and cooling tower. | Brayton cycle |
| Reaction turbine | Design of a Turbine where energy is extracted from the steam predominantly by a change in pressure of the steam The vanes (stationary components fixed to the casing) direct the steam toward the blades (rotating components attached to the rotor) which produce a force on the rotor in a way similar to an aeroplane wing. The shape of the blade causes a difference in steam from one side of the blade to the other, causing the rotor to turn. | Impulse turbine |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| SA | Sealing air The sealing air fan provides air pressure to joints and seals around the moving parts of the pulveriser to prevent pulverised fuel and primary air leaking out. | Pulverizer |
| Safety valve | A flow control device designed to prevent the pressure in a vessel exceeding its design pressure |
| Term | Explanation and discussion | References and related terms | |
|---|---|---|---|
| Tandem compound | A design of turbine where multiple cylinders are arranged in line on a single shaft | Cross compound | |
| Tap changer | A device in a transformer to change the number of coils used | Since the voltage ratio of a transformer is based on the ratio of the number of turns between the primary and secondary coils, changing the number of turns changes the voltage. | Transformer |
| TDS | Total dissolved solids A measure of the impurities contained in cooling water | Langelier saturation index |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| UCG | Underground coal gasification | Gasification |
| Ultimate analysis | The detailed chemical analysis of a fuel that indicates the contents of carbon, hydrogen, sulphur, nitrogen, chlorine, oxygen, and ash – as percentages by mass In some analyses, the ash content may be listed as the specific elements, for example silicon and iron, as these determine the ash fusion temperature and associated slagging behaviour. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Valves wide open | One of three modes describing the configuration of the unit around full load As the name implies, in this mode the governor valves are positioned at 100%. The boiler is at rated pressure. Often abbreviated as VWO. | Maximum continuous rating |
| V2G | Vehicle to grid Supplying the electricity network with electricity stored in the batteries of battery electric vehicles or plug-in hybrid electric vehicles |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Warm start | Start of a unit after a shutdown of less than 96 hours but more than 6 hours The type of warm start, or whether it is in fact a cold start, depends on the degree of cooling experienced by the boiler and turbine during the shutdown. For example, the boiler may have been subjected to a forced cool to enable rapid progress on repair of a tube leak. |
|
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| X and Y protection | Duplicated electrical protection schemes in a power plant control system Typically, protection of electrical power systems is duplicated to ensure that the plant remains properly secure in the event of a failure of one of the protection systems. To ensure that the protection systems are completely independent of each other, they are installed by different vendors. |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
| Yaw | Movement of a wind turbine nacelle from side to side. When the wind direction changes, this movement orients the rotor to the direction of the wind, to maximise the power output. | Degrees of freedom (mechanics) |
| Term | Explanation and discussion | References and related terms |
|---|---|---|
A glossary also known as a vocabulary or clavis, is an alphabetical list of terms in a particular domain of knowledge with the definitions for those terms. Traditionally, a glossary appears at the end of a book and includes terms within that book that are either newly introduced, uncommon, or specialized. While glossaries are most commonly associated with non-fiction books, in some cases, fiction novels may come with a glossary for unfamiliar terms.
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia (basidiomycetes) or paraphyses (ascomycetes). Cystidia are often important for microscopic identification. The subhymenium consists of the supportive hyphae from which the cells of the hymenium grow, beneath which is the hymenophoral trama, the hyphae that make up the mass of the hymenophore.
In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather, while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In meteorology, atmospheric divergence aloft occurs in two kinds of places:
Lists of mathematics topics cover a variety of topics related to mathematics. Some of these lists link to hundreds of articles; some link only to a few. The template to the right includes links to alphabetical lists of all mathematical articles. This article brings together the same content organized in a manner better suited for browsing. Lists cover aspects of basic and advanced mathematics, methodology, mathematical statements, integrals, general concepts, mathematical objects, and reference tables. They also cover equations named after people, societies, mathematicians, journals, and meta-lists.
In zoological nomenclature, a type species is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen(s). A similar concept is used for suprageneric groups and called a type genus.
An antagonist is a character in a story who is presented as the chief foe of the protagonist.
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple or compound. The edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. For more terms describing other aspects of leaves besides their overall morphology see the leaf article.
Trailokya literally means "three worlds" It can also refer to "three spheres," "three planes of existence," "three realms" and "three regions."
A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For instance, cold fronts can bring bands of thunderstorms and cumulonimbus precipitation or be preceded by squall lines, while warm fronts are usually preceded by stratiform precipitation and fog. In summer, subtler humidity gradients are known as dry lines can trigger severe weather. Some fronts produce no precipitation and little cloudiness, although there is invariably always a wind shift.
In taxonomy, a nomen nudum is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate description. This makes it a "bare" or "naked" name, which cannot be accepted as it stands. A largely equivalent but much less frequently used term is nomen tantum.
A modillion is an ornate bracket, more horizontal in shape and less imposing than a corbel. They are often seen underneath a cornice which it helps to support. Modillions are more elaborate than dentils. All three are selectively used as adjectival historic past participles as to what co-supports or simply adorns any high structure of a building, such as a terrace of a roof, parapet, pediment/entablature, balcony, cornice band or roof cornice. Modillions occur classically under a Corinthian or a Composite cornice, but may support any type of eaves cornice. They may be carved or plain.
In botany, a peduncle is a stalk supporting an inflorescence or a solitary flower, or, after fecundation, an infructescence or a solitary fruit. The peduncle sometimes has bracts at nodes. The main axis of an inflorescence above the peduncle is the rachis. There are no flowers on the peduncle but there are flowers on the rachis.
Landfall is the event of a storm moving over land after being over water. More broadly, and in relation to human travel, it refers to 'the first land that is reached or seen at the end of a journey across the sea or through the air, or the fact of arriving there.
The follow articles comprise the glossary of education-related terms:
In cave diving, a Torricellian chamber is a cave chamber with an airspace above the water at less than atmospheric pressure. This is formed when the water level drops and there is no way for more air to get into the chamber. In theory such chambers could pose a risk of decompression sickness to divers, similar to flying after diving. Also, in a Torricellian chamber the diver's depth gauge is unlikely to give an accurate reading of pressure as most depth gauges are not designed to show depths less than zero.
A horse length, or simply length, is a unit of measurement for the length of a horse from nose to tail, approximately 8 feet (2.4 m).
Nomen illegitimum is a technical term, used mainly in botany. It is usually abbreviated as nom. illeg. Although the International Code of Nomenclature for algae, fungi, and plants uses Latin terms for other kinds of name, the glossary defines the English phrase "illegitimate name" rather than the Latin equivalent. However, the Latin abbreviation is widely used by botanists and mycologists.
This is a glossary of technical terms, jargon, diver slang and acronyms used in underwater diving. The definitions listed are in the context of underwater diving. There may be other meanings in other contexts.