🚀 go-pugleaf

In message <gpmjcr$aav$1@news.motzarella.org>, ~misfit~ 
<misfit61nz@yahoo.com.au> writes


>> There is nearly always surplus capacity on the grid during off peak
>> times as because of the sheer size and mass of large turbine rotors
>> it takes several hours to run them up, also most turbine failures
>> occur during run down/up so engineers prefer to keep them under load
>> anyway,
>
>I think you'll find that they like to keep them spinning, but not 'under
>load', at least no more load than minimum.

They keep the rotors turning because if you leave them stopped they 
start to bend under their own weight.

It doesn't take a lot of steam to keep the rotors turning so they don't 
burn very much fuel. As soon as you draw any power from them they slow 
down unless you turn up the steam pressure, which requires more fuel. 
The generators that are under load are kept at a fixed 3600rpm by 
adjusting the steam pressure; more load, more steam required. So the 
fuel usage is mostly dependent on the load. If you cut down the amount 
of electricity being drawn from the grid you cut down the amount of fuel 
being used.

There is never any power that's not being used and increased load 
immediately increases the amount of fuel being used. The systems are 
automated so that when a generating set is put under load it slows down. 
The slowdown triggers the steam valve to open more. Opening the steam 
valve draws in more water. Drawing in more water cools the boiler. 
Cooling the boiler triggers an increase in the fuel feed.

Some systems can respond to increased demand in less than a second. 
Others take a lot longer. Slow systems like nuclear reactors are used 
for base-load. Fast response systems are used for peak loads like 
half-time at the cup-final.




-- 
Bernard Peek
London, UK. DBA, Manager, Trainer & Author.