|Re: OT-A Slow Day in The Cabinet Shop
Group: rec.woodworking · Group Profile
Author: dpb Date: Jun 7, 2010 23:25
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+
From B&W (Babcock & Wilcox) site...
> 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.
> 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
> 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).