Layout of diesel power plant

A diesel power plant is a generating station in which a diesel (compression-ignition) engine is the prime mover driving an alternator. It is used for standby, peak load and small isolated loads.

Schematic of a diesel power plant

 Air filter -> Intake    Exhaust -> Silencer -> Stack
                 |          ^
 Fuel tank  +----v----------+----+   coupling  +-----+
 -> filter->| DIESEL ENGINE      |============| Alt |->Bus
 -> pump -> | (injectors)        |            +-----+
 -> injector+--+-----------+-----+               |
               |           |                  Exciter
     Cooling water     Lube oil
     pump <-> cooling  pump <-> oil
     tower/radiator    cooler, filter
     Starting: compressed air bottles / electric motor

Systems of a diesel power plant

1. Engine and alternator: the diesel engine (2- or 4-stroke) converts the chemical energy of fuel into mechanical work; it is coupled to an alternator with its exciter on a common bed plate.

2. Fuel supply system: storage tank → transfer pump → day tank → filters → fuel (booster) pump → fuel injection pump → injectors. It stores, cleans and injects the correct quantity of fuel at high pressure at the right time.

3. Air intake system: air filter, intake ducts and (often) a turbo-charger/supercharger with intercooler. It supplies clean air for combustion.

4. Exhaust system: exhaust manifold, silencer (muffler) and chimney. It removes exhaust gases and reduces noise; exhaust heat may be recovered in a waste-heat boiler or to heat oil/water.

5. Cooling system: water pump, jacket, heat exchanger, radiator or cooling tower. It removes about 30 % of fuel heat to keep cylinder, piston and valves within safe temperature.

6. Lubrication system: oil sump, pump, filter and oil cooler. It reduces friction and wear and also cools pistons and bearings.

7. Starting system: compressed-air bottles with compressor (large engines), electric starter motor with battery (small engines), or an auxiliary petrol engine. The engine cannot start by itself.

8. Governing system: governor that changes the fuel supply to keep speed (frequency) constant as load varies.

9. Electrical system: alternator, exciter, switchgear, protection, and control panel.