Available capacity of a thermal power station (kW)

The available capacity (Pd)” of an installation is the maximum power at which t can be operated under the prevailing conditions, assuming no transmission network limitations. Available capacity may be gross or net, like the maximum electrical capacity. This capacity depends only on the technical state of the equipment and its ability to operate, not on the dispatching requirements. Available capacity in continuous operation is that which can be maintained for a prolonged period (as for maximum electrical capacity). The available capacity of an installation (Pd) is equal tot its maximum electrical capacity (Pm) less the total unavailable capacity (Pit) . The concept of available capacity can be applied to a unit or a power station and may be extended to a group of power stations. The available capacity of a group of power stations must represent all power stations in the group whether or not they are in operation. TE calculation of available capacity differs for thermal conventional and co-generation installations. (UNIPEDE 1991)

Average heat rate of a thermal power station (kJ/kWh)

The "average heat rate of a thermal power station" for a given period is the quotient of the heat consumption of a conventional thermal power station and the electrical energy produced during that period. It is recommended that the net calorific value (QNP) at constant pressure be used. If the gross calorific value is used this should be clearly indicated. Assessment of the heat content of the fuel burnt is to be related to the closest practical point to the place of combustion, e.g. at entry to the unit fuel bunkers. It is recognised that not all power stations will perform actual measurement at this point and that minor adjustment may be necessary. No allowance is to be made for degradation of the heat content (calorific value) of value held in stock. (UNIPEDE 1991)

Conventional steam power station

A "conventional steam power station" is usually taken to refer to one in which the energy in fossil fuels is converted into electrical energy by means of a steam turbine. (UNIPEDE 1991)

Electrical energy reserve of a conventional thermal power station (kWh)

The "electrical energy reserve of a conventional thermal power station" at a given time is the sum, for each kind of fuel in stock, of the quotients of the quantity stocked and the average monthly power station consumption of that fuel per kWh supplied and measured at the output terminals of the power station, taking account of the operating programme of the power station during that period. Note: This concept of electrical energy reserve of a thermal power station is obviously not applicable where the fuel used is blast furnace gas or natural gas, nor is it applicable to certain pithead power stations which do not have a fuel stock as such Where a thermal power station consumes mixtures of fuels, its "electrical energy reserve" should be calculated only on the tonnage of the mixture that can be constituted with the fuel in stock. (UNIPEDE 1991)

Gross calorific value of conventional fuel (kJ/kg)

The "gross calorific value of conventional fuel" at constant volume is the number of kilojoules of heat measured as being liberated when 1 kilogram of fuel is burned in oxygen in a calorimeter bomb under standard conditions are taken to consist of the gases, oxygen, carbon dioxide, sulphur dioxide and nitrogen, liquid water in equilibrium with its vapour and saturated with carbon dioxide, and solid ash. (UNIPEDE 1991)

Heat consumption of a conventional thermal power station (kJ)

The "heat consumption of a conventional thermal power station" is the heat equivalent of the fuel consumed. It is the product of the weight of fuel burnt and its calorific value. It is recommended that the net calorific value (QNP) at constant pressure be used. If the gross calorific value is used this should be clearly indicated. Assessment of the heat content of the fuel burnt is to be related to the closest practical point to the place of combustion, e.g. at entry to the unit fuel bunkers. It is recognised that not all power stations will perform actual measurement at this point and that minor adjustment may be necessary. No allowance is to be made for degradation of the heat content (calorific value) of value held in stock. (UNIPEDE 1991)

Maximum net heating capacity of a co-generation power station (kJ/s)

The "maximum net heating capacity of a co-generation power station" is the net heat transfer from the installation to the heating network. It is the heat in the hot fluid supplied to the heating network less, where appropriate, the heat returned to the installation by the fluid returning from the network. This capacity is net, meaning that it is related to the point of entry to the heating network, and excludes the heat consumed by the installation’s auxiliaries which use a hot fluid (space heating, liquid fuel heating, etc …) and losses in the installation/network heat exchangers. (UNIPEDE 1991)

Thermal efficiency and fuel consumption

The heat equivalent of the fuel consumed is the product of the weight of fuel burnt and its calorific value. Gaseous fuels may be metered by volume and the appropriate calorific value used. All fuels burnt at the power station including those used for auxiliary plant, auxiliary generators, maintaining boiler pressure, testing plant whilst off-load starting-up plant, and heating buildings directly associated with the power station are to be included. (UNIPEDE 1991)

Thermal efficiency of a thermal power station (%)

The "thermal efficiency of a thermal power station", for a given period, is the quotient of the heat equivalent of 1 kWh and the average heat rate expressed in the same units. (UNIPEDE 1991)

Thermal efficiency of conventional power stations within the system (%)

The "thermal efficiency of conventional plants within the system" for a given period is the quotient of the heat equivalent of 1 kWh and the heat rate of conventional power stations within the system, expressed in the same units. (UNIPEDE 1991)

Thermal generator set

A "thermal generator set" normally consists of a thermal prime mover mechanically connected to one or more generator(s) of electrical energy. (UNIPEDE 1991)

Thermal power station

A "thermal power station" is a power station in which the primary energy is converted to electrical energy using a thermodynamic process. (UNIPEDE 1991)

Thermal power station unit

A "thermal power station unit" consists of the steam generator(s), the thermal prime mover(s), the electrical generator(s), the generator transformer(s), the related steam and other circuits and auxiliary services, which form a coordinated system to convert the heat energy of fuels into electrical energy. The essential characteristic of a unit is that it is self-contained. (UNIPEDE 1991)