17-09-2012, 10:58 AM
Steam Turbines
Steam_Turbines.pdf (Size: 190.09 KB / Downloads: 78)
Why they are used for CHP?
Steam turbines have been generating power in America for many years. Power generated by steam turbines have lit the first light bulbs and propelled our ships for over 100 years. In fact, the first power plant (run by Thomas Edison using his dynamos and located at Pearl Street in New York City) was a CHP plant that generated power using a steam turbine. The excess steam was used to heat homes. Today, most of the electricity produced in the United States is done so by steam turbines. It is safe to say the steam turbines are a known, well understood and proven technology.
Because a steam turbine runs off of steam produced by a boiler, it can support many different types of fuels. Natural gas, coal, nuclear, wood, municipal solid waste and more can all be used to run a steam turbine. As a result, facilities that have an excess of waste products such as oil or wood tend to implement steam turbines. As the figure below indicates, current steam turbine CHP systems run off of a variety of fuels.
Brief technological description:
Steam turbines are slightly different than other CHP prime movers in that they require a separate boiler or “HRSG” (Heat Recovery Steam Generator) to create its working fluid (steam). Sometimes, plants will already have a boiler producing steam for a process or to satisfy a heating/cooling load and rather than using a “pressure reducing valve” to “isenthalpically” reduce the pressure of the steam, they will run the steam through a “back pressure steam turbine” and generate electricity. In CHP applications, a boiler or HRSG will generate steam which will be put through a steam turbine. The steam turbine will produce electricity and the remaining exhaust steam can be used for hot water or heating/cooling.
Costs:
Steam turbine plus boiler installation costs are between $800-$1000/kW. If a boiler is already in place, the installation cost of just a steam turbine alone is $400-$800/kW. Maintenance costs for the steam turbine are estimated to be $0.004/kWhr. Steam turbines have been known to last beyond 50 years with over 99% availability. Table 1 gives cost info for steam turbines only.
Emissions:
Steam turbines do not emit anything themselves. However, the steam generator emits pollutants. Therefore, the emissions from a steam turbine system are highly variable and depend on the type of fuel being used to create the steam and the method by which steam is created. Boilers will emit NOx, SOx, PM, CO, and CO2. Typical boiler emissions are shown in the following table.
Steam_Turbines.pdf (Size: 190.09 KB / Downloads: 78)
Why they are used for CHP?
Steam turbines have been generating power in America for many years. Power generated by steam turbines have lit the first light bulbs and propelled our ships for over 100 years. In fact, the first power plant (run by Thomas Edison using his dynamos and located at Pearl Street in New York City) was a CHP plant that generated power using a steam turbine. The excess steam was used to heat homes. Today, most of the electricity produced in the United States is done so by steam turbines. It is safe to say the steam turbines are a known, well understood and proven technology.
Because a steam turbine runs off of steam produced by a boiler, it can support many different types of fuels. Natural gas, coal, nuclear, wood, municipal solid waste and more can all be used to run a steam turbine. As a result, facilities that have an excess of waste products such as oil or wood tend to implement steam turbines. As the figure below indicates, current steam turbine CHP systems run off of a variety of fuels.
Brief technological description:
Steam turbines are slightly different than other CHP prime movers in that they require a separate boiler or “HRSG” (Heat Recovery Steam Generator) to create its working fluid (steam). Sometimes, plants will already have a boiler producing steam for a process or to satisfy a heating/cooling load and rather than using a “pressure reducing valve” to “isenthalpically” reduce the pressure of the steam, they will run the steam through a “back pressure steam turbine” and generate electricity. In CHP applications, a boiler or HRSG will generate steam which will be put through a steam turbine. The steam turbine will produce electricity and the remaining exhaust steam can be used for hot water or heating/cooling.
Costs:
Steam turbine plus boiler installation costs are between $800-$1000/kW. If a boiler is already in place, the installation cost of just a steam turbine alone is $400-$800/kW. Maintenance costs for the steam turbine are estimated to be $0.004/kWhr. Steam turbines have been known to last beyond 50 years with over 99% availability. Table 1 gives cost info for steam turbines only.
Emissions:
Steam turbines do not emit anything themselves. However, the steam generator emits pollutants. Therefore, the emissions from a steam turbine system are highly variable and depend on the type of fuel being used to create the steam and the method by which steam is created. Boilers will emit NOx, SOx, PM, CO, and CO2. Typical boiler emissions are shown in the following table.