On Jun 7, 5:25 pm, dpb
non.net> wrote:> Lew Hodgett wrote:
>> "dpb" wrote:
>
>>> Large fossil-fired generation is in the 35-36%%; Bull Run mentioned
>>> earlier is about 38%%; new super-criticals are up to at least pushing
>>> the 40%% mark if none have yet broken it.
>> ----------------------------------------
>> Glad to see some improvement over the years.
>
> ...
>
> There's not been a sizable central-station generation plant that had a
> thermal efficiency <30%% built since before WW-II I'd think. Even the
> old Kingston Fossil units, still operate in the low 30%% range after 50+
> years.
>
> From B&W (Babcock & Wilcox) site...
>
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>> Efficiency at a power plant is measured by the ratio of the
>> electricity generated compared to the energy in the fuel used.
>> Increasing steam temperatures and pressures provides more energy to
>> the steam turbine, enabling higher efficiency and allowing the same
>> amount of electricity to be generated by burning less coal. This
>> results in less production of CO2 and pollutants derived by coal
>> combustion, reduced fuel costs and smaller and less costly power
>> plants for the same power generated.
One big difference in pollutants is to burn that ' clean coal' those
adverts on US TV talk about. *smirk*
Seriously, one plant I worked at had a pile of 'summer coal' for those
hazy days.
>
>> Many existing US coal-fired plants operate with relatively low steam
>> temperatures and pressures (subcritical steam conditions). These old
>> plants are generally used during high electricity demand periods
>> because of the low generation efficiency, typically in the 30-35
>> percent range. When steam conditions exceed the combination of both
>> 760F and 3200psi, the steam (or working fluid) is said to reach
>> supercritical conditions. Efficiencies of these plants exceed 37
>> percent.
>
>> Supercritical plants with efficiencies around 40 percent are already
>> commercially available and being increasingly deployed. R&D projects
>> with advanced materials and manufacturing methods are underway to
>> permit increases of working fluid temperatures to 1200F, and then to
>> around 1400F. When this happens efficiencies will rise above 43
>> percent toward 48 percent.
>
>> It is important to note when evaluating coal plant performance, that
>> efficiency numbers, taken at face value, can be misleading. The US
>> convention for calculating efficiency, called higher heating value
>> (HHV), is different from that used in Europe, lower heating value
>> (LHV). One of the factors responsible for the difference is the way
>> moisture in coal is treated in the efficiency calculation. There are
>> other factors that enter into the calculation as well. The result is
>> that, for virtually identical plant performance (coal fuel in vs.
>> power out), the US efficiency (HHV basis) would be reported as being
>> up to 5 percent lower than European efficiency (LHV basis).
>
> --
One of OPG's stations had a blend B&W and CE boilers. Circ pumps and
tangential fires made the CE's my favourites. Those were only 500'MW
single shaft two-pole, the B&W were tandems. Big wheels on the LP
side. None were over 30%% efficient.
