Coal power plant efficiency

The addition of H2O and CO2 to the fuel gas modifies the equilibrium gas composition so that the formation of CH4 is not favored. Carbon deposition can be reduced by increasing the partial pressure of H2O in the gas stream. The measurements (20) on 10 cm x 10 cm cells at 650°C using simulated gasified coal GF-1 (38% H2/56% CO/6% CO2) at 10 atm showed that only a small amount of CH4 is formed. At open circuit, 1.4 vol% CH4 (dry gas basis) was detected, and at fuel utilizations of 50 to 85%, 1.2 to 0.5% CH4 was measured. The experiments with a high CO fuel gas (GF-1) at 10 atmospheres and humidified at 163°C showed no indication of carbon deposition in a subscale MCFC. These studies indicated that CH4 formation and carbon deposition at the anodes in an MCFC operating on coal-derived fuels can be controlled, and under these conditions, the side reactions would have little influence on power plant efficiency. 

The output temperature is given by the ambient temperature of the waste-heat loop and can be taken to be 30°C for purposes of estimation. The input temperature of the steam is limited by physical constraints on the reactor primary cooling loop to be about 300°C. Therefore, the maximum Carnot efficiency is approximately carnot = (573 K-303 K)/573 K = 0.47, whereas the actual efficiency is typically 8dec = 0.35 when measured as electrical power outside the plant to total thermal power in the core. For comparison, a coal-powered plant might have values of carnot = 0.65, 8eiec = 0.5 due to higher steam temperatures... 

When coal is used in electricity generation, the heat is used to create steam, which is then used to power turbine generators. Approximately 40% of Earth s current electricity production is powered by coal, and the total known deposits recoverable by current technologies are sufficient for at least 300 years of use. Modem coal power plants utilize a variety of techniques to limit the harmfulness of their waste products and to improve the efficiency of burning, although these techniques are not widely implemented in some countries, as they add to the capital cost of the power plant. 

In a gasification-based power plant, the hot, high pressure coal gases from the gasifier turn a gas turbine. Hot exhaust from the gas turbine is then fed into a conventional steam turbine, producing a second source of power. This dual, or combined cycle arrangement of turbines is not possible with conventional coal combustion. It offers major improvements in power plant efficiencies. 

A tremendous increase in energy efficiency together with certain limitations regarding comfort and lifestyle permits a second age of fossil fuels. The carbon capture in coal power plants facilitates a long-term electricity production from coal. 

The increased efficiency of the combined cycle for electrical power generation results in a 50% decrease in carbon dioxide emissions compared to conventional coal power plants. As the technology is required to develop economical methods of carbon sequestration, the removal of carbon dioxide from combustion by-products to prevent its release to the atmosphere, coal gasification units could be modified to further reduce their climate change impact because a large part of the carbon dioxide generated can be separated from the syngas before combustion. 

Case 1 Importing Power from Coal Power Plants The average efficiency for... 

Efficient Carbon Capture for Coal Power Plants... 

While the steam generator efficiency t)sg 0.92), the steam turbine efficiency (j/x = 0.9-0.92), the generator efficiency (t/q > 0.98), and the corresponding efficiency for the power plant s electrical auxiliary power consumption ( /aux io 0.93) all have relatively high values above 0.9, the net efficiency of a coal-fired steam power plant is mainly affected by the thermal efficiency of the cycle /th,id> which today is about 0.55. Besides the minimization of losses by an optimized flue gas heat utilization, the application of optimized turbine blading, or the reduction of the auxiliary power consumption, the main potential for enhancing the overall power plant efficiency can be seen in increasing the live steam parameters. 

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