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Introduction

Modern fossil-fuelled power stations are a complex assembly of plant and apparatus, which converts chemical energy from the fuel into electrical energy.

This energy transformation process is carried out in three stages:-

1. Chemical energy in the fuel (gas or oil) is released as heat in the boiler when it burns with air.
2. Heat converts water in boiler tubes to steam, which is then used to drive a turbine that converts energy into mechanical rotational energy.
3. Rotational energy drives an alternator to produce electrical energy.

Fuel

Natural gas is delivered to Ballylumford Power Station from the North Sea via the subsea pipeline from Scotland to Northern Ireland (S.N.I.P) at high pressure (15-75bars).

Gas Pressure is reduced at pressure reducing stations (PRS's) before supplying the low Nox gas/oil burners on the main plant boilers. Heavy fuel oil is maintained as a back up emergency fuel when natural gas is not available.

Boiler

The chemical energy found in the fuel is released into heat energy in the boiler.

The heat liberated converts the water in the boiler tube walls into steam to drive the turbine. The boilers supply steam at a temperature of 540oC at pressures up to 165 bar. Each boiler can be fired on natural gas or heavy fuel oil using 12 off low Nox burners to burn the fuel.

Turbine

Heat energy, in the form of steam, supplied by the boiler is converted into mechanical energy in the turbine. The turbine and generator are coupled on a single shaft rotating at a controlled speed of 3000rpm (50Hz). The turbine comprises three sections:-

1. A high pressure turbine (H.P.) developing 26% of the power.
2. An intermediate pressure turbine (I.P.) developing 41% of the power.
3. A low pressure turbine (L.P.) developing 33% of the power.

Generator

The final stage of the energy conversion process takes place in the generator where mechanical energy is converted into electrical energy.

As the turbine shaft spins it rotates the generator rotor (electromagnet) within the stator windings and induces an electrical current therein, which is then fed into the Northern Ireland electricity grid.

Transformer

Electricity is produced at 13.8 to 15.0 kilovolts (kV) and raised by a step up Generator transformer to 275kV before being fed to Northern Ireland Electricity plc grid. High voltages are used in the transmission system to minimise electrical losses.

'B' Station Plant System