On Mon, 27 Feb 2012 23:04:49 +0000, Andy Champ
wrote:

On 27/02/2012 18:14, The Other Mike wrote:
Like I said hours ago. A none evert

A what?

Where the hell did 'evert' come from?

Just accept it's a tennis player and nothing else

On CCGT - shouldn't you be able to fire it up in open mode, in a minute
or so to cover a peak, and let the steam come in later to get efficiency?

Yes, but that is wasteful and shags mechanicals - think of it like
firing up a cold engine and immediately taking it to 6000 revs, or
letting it warm up slowly over half an hour of driving at 40mph before
flooring it.


--

The Other Mike wrote:
On Mon, 27 Feb 2012 23:04:49 +0000, Andy Champ
wrote:

On 27/02/2012 18:14, The Other Mike wrote:
Like I said hours ago. A none evert
A what?

Where the hell did 'evert' come from?

Just accept it's a tennis player and nothing else

Not quite right...

evert:
to turn inside out; to turn outward.


On CCGT - shouldn't you be able to fire it up in open mode, in a minute
or so to cover a peak, and let the steam come in later to get efficiency?

Yes, but that is wasteful and shags mechanicals - think of it like
firing up a cold engine and immediately taking it to 6000 revs, or
letting it warm up slowly over half an hour of driving at 40mph before
flooring it.


latest CCGT will come up in OCGT - about as fast as a jet engine warms
up. Like a few minutes ramping up over 12-30 minutes: It takes longer
for the steam circuits to come on stream and double the power. But 15-20
mins for half power (and full fuel gulp)

Did you know that it takes 10,000 euros of fuel to fire up a big CCGT
set? all of that is lost ifyou switch it off and let it cool down again.





--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Wed, 29 Feb 2012 23:45:25 +0000, The Other Mike wrote:

This is the loading profile of one 500MW coal fired unit dating from
the late 1960's that had been in the high 400's till 2230 the day
before, before coming offline at 2300.

353MW per hour ramp rate between 0701 and 0812

I make it 363MW but whats 10MW(*)... B-)

(480-50)/71)*60

So a station with 4 units in a similar state could ramp up not far
short of 1.5GW/hour. Just 3 other stations with 4 units each gives
5.8GW/hr ramp rate.

So the loss of 400MW from Tilbury can be made up from a *single* unit
at a coal station in less than 2hrs. Spread it out over a eight units
(50MW each) and you are down to minutes...

Would it be safe to assume that this is a controlled and steady
demand lead ramp rate rather than an "Oh F..k we need more power and
we need it now" ramp rate.

--
Cheers
Dave.

Dave Liquorice wrote:
On Wed, 29 Feb 2012 23:45:25 +0000, The Other Mike wrote:

This is the loading profile of one 500MW coal fired unit dating from
the late 1960's that had been in the high 400's till 2230 the day
before, before coming offline at 2300.

353MW per hour ramp rate between 0701 and 0812

I make it 363MW but whats 10MW(*)... B-)

(480-50)/71)*60

So a station with 4 units in a similar state could ramp up not far
short of 1.5GW/hour. Just 3 other stations with 4 units each gives
5.8GW/hr ramp rate.

So the loss of 400MW from Tilbury can be made up from a *single* unit
at a coal station in less than 2hrs. Spread it out over a eight units
(50MW each) and you are down to minutes...

Would it be safe to assume that this is a controlled and steady
demand lead ramp rate rather than an "Oh F..k we need more power and
we need it now" ramp rate.

yes..that sort of variation is down to Dinorwig which can go from zero
to hero (2GW?) in less than 5 minutes IIRC.

Oh. Wiki of course

"The power station comprises six 300MW GEC generator/motors coupled to
Francis-type reversible turbines. The generators are vertical shaft,
salient pole, air cooled units each having 12 electromagnetic poles
weighing 10 tonnes a piece, producing a terminal voltage of 18kV,
synchronous speed is 500rpm. From standstill, a single 450-tonne
generator can synchronise and achieve full load in approximately 75
seconds. With all six units synchronised and spinning-in-air (compressed
air), 0MW to 1800MW load can be achieved in approximately 16 seconds.[6]
Once running, the station can provide power for up to 6 hours before
running out of water."

Now THAT is impressive.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Thu, 01 Mar 2012 00:14:08 +0000, The Natural Philosopher
wrote:

The Other Mike wrote:
On Mon, 27 Feb 2012 23:04:49 +0000, Andy Champ
wrote:

On 27/02/2012 18:14, The Other Mike wrote:
Like I said hours ago. A none evert
A what?

Where the hell did 'evert' come from?

Just accept it's a tennis player and nothing else

Not quite right...

Oh but it is

http://en.wikipedia.org/wiki/Chris_Evert

evert:
to turn inside out; to turn outward.

That would explain it too, and as to why it was in my spell checker

On CCGT - shouldn't you be able to fire it up in open mode, in a minute
or so to cover a peak, and let the steam come in later to get efficiency?

Yes, but that is wasteful and shags mechanicals - think of it like
firing up a cold engine and immediately taking it to 6000 revs, or
letting it warm up slowly over half an hour of driving at 40mph before
flooring it.


latest CCGT will come up in OCGT - about as fast as a jet engine warms
up. Like a few minutes ramping up over 12-30 minutes: It takes longer
for the steam circuits to come on stream and double the power. But 15-20
mins for half power (and full fuel gulp)

Did you know that it takes 10,000 euros of fuel to fire up a big CCGT
set? all of that is lost ifyou switch it off and let it cool down again.

They can afford it

A coal fired station from a cold start is not much different.

--

On Thu, 01 Mar 2012 00:21:49 +0000 (GMT), "Dave Liquorice"
wrote:

On Wed, 29 Feb 2012 23:45:25 +0000, The Other Mike wrote:

This is the loading profile of one 500MW coal fired unit dating from
the late 1960's that had been in the high 400's till 2230 the day
before, before coming offline at 2300.

353MW per hour ramp rate between 0701 and 0812

I make it 363MW but whats 10MW(*)... B-)

(480-50)/71)*60

So a station with 4 units in a similar state could ramp up not far
short of 1.5GW/hour. Just 3 other stations with 4 units each gives
5.8GW/hr ramp rate.

So the loss of 400MW from Tilbury can be made up from a *single* unit
at a coal station in less than 2hrs. Spread it out over a eight units
(50MW each) and you are down to minutes...

Would it be safe to assume that this is a controlled and steady
demand lead ramp rate rather than an "Oh F..k we need more power and
we need it now" ramp rate.

It is planned and can't be rushed, even though they are hot, having
being at up to 568 deg C a few hours before, thermal expansion of the
turbine casings and steam chests are strictly controlled to prevent
cracking and differential expansion Plus in the later stages of the
boiler you need the transition from wet steam to dry steam to take
place where there the boiler tubes are of a specific metallurgy. The
control systems take care of most of it nowadays. The timing for
synchronisation and for a defined load can be spot on within a minute
or so. But it's nothing that couldn't be achieved with a good human
operator 40 years ago.

Of course when at 'full load' it is nearly always possible to overfuel
a coal or oil fired unit for a short period, the emissions go out of
the window but acid rain never existed anyway It's possible to
get another 20MW out of some 500's and about 30MW out of a 660 for
about 20 mins or so. Some 500's have always done more than the
nameplate rating or have been uprated during a major overhaul - 500
generated, 480 sent out was the original design rating across the
board allowing 20MW for the ancillaries, some have always failed to
meet that.



--

On 01/03/2012 10:07, The Other Mike wrote:
On Thu, 01 Mar 2012 00:14:08 +0000, The Natural Philosopher
wrote:

The Other Mike wrote:
On Mon, 27 Feb 2012 23:04:49 +0000, Andy
wrote:

snip

On CCGT - shouldn't you be able to fire it up in open mode, in a minute
or so to cover a peak, and let the steam come in later to get efficiency?

Yes, but that is wasteful and shags mechanicals - think of it like
firing up a cold engine and immediately taking it to 6000 revs, or
letting it warm up slowly over half an hour of driving at 40mph before
flooring it.


latest CCGT will come up in OCGT - about as fast as a jet engine warms
up. Like a few minutes ramping up over 12-30 minutes: It takes longer
for the steam circuits to come on stream and double the power. But 15-20
mins for half power (and full fuel gulp)

Did you know that it takes 10,000 euros of fuel to fire up a big CCGT
set? all of that is lost ifyou switch it off and let it cool down again.

They can afford it

A coal fired station from a cold start is not much different.


Well, a quick google tells me an Airbus can take off as soon as the oil
has got to more than -10 celsius. Presumably a power station isn't that
cold... but then probably hasn't got that kind of lube either. Jets
will run quite well when cold. Other aircraft seem to need 4 minutes...
I'm not going to google that hard.

I didn't know it took EUR10k to fire the thing up, but I'm not at all
surprised.

Coal is a different matter. Until you've got the steam up to heat you
get nothing. Zilch, rien, nada.

Andy

On Thu, 01 Mar 2012 21:46:58 +0000, Andy Champ
wrote:

Well, a quick google tells me an Airbus can take off as soon as the oil
has got to more than -10 celsius. Presumably a power station isn't that
cold... but then probably hasn't got that kind of lube either. Jets
will run quite well when cold. Other aircraft seem to need 4 minutes...
I'm not going to google that hard.

I didn't know it took EUR10k to fire the thing up, but I'm not at all
surprised.

Coal is a different matter. Until you've got the steam up to heat you
get nothing. Zilch, rien, nada.

It's not just oil temperature. A typical aircraft engine on a 747
weighs maybe 6 tonnes. CCGT turbine weighs about the same as a fuly
laden 747. The engine core diameter on a CCGT is larger than the
entire engine on 747.

You can run them open cycle at far lower output, 10 minutes or so from
start to around 50% of their normal closed rating, the limiting factor
being the rate of temperature rise of a number of key parts to reduce
differential expansion.

--