Steam power plants

State-of-the-art first law efficiencies of boilers are typically between 85% and 90%, that is, the fraction of fuel energy value (heat of combustion) captured in steam. It is not surprising that the efficiency is not 100%, since the flue gas that exits the boiler is much hotter than the temperature of the environment and therefore takes with it some of the energy ( heat goes up the chimney ). Typical conditions in a steam cycle are as given in Table 9.6 [3,10]. In this table, we have not included the exergies of the fuel, since we will 

Computation of the thermodynamic efficiency in a steam cycle (1) inlet, (2) pre-combustion, (3) post-combustion, pre-compressor, (4) post-turbine to exhaust, (5) gas inlet. 

The steam production allows for the computation of the exergy flow at various points (Table 9.7). For example, the exergy flow at point (1) is simply 2.73 x 10-4 x 1402.8 = 0.38kj/s. The exergy value of the flue gas stream (5) is computed by using the first law efficiency and realizing that the flue gas stream is a heat stream being discarded  

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A key development in water-tube furnace design was the Babcock and WHcox boHet of 1877 (Fig. 2) (3). This can be considered the direct evolutionary ancestor of the 1000 MW steam power plants a century later (see Steam). 

Creep of Thick-walled Cylinders. The design of relatively thick-walled pressure vessels for operation at elevated temperatures where creep caimot be ignored is of interest to the oil, chemical, and power industries. In steam power plants, pressures of 35 MPa (5000 psi) and 650°C are used. Quart2 crystals are grown hydrothermaHy, using a batch process, in vessels operating at a temperature of 340—400°C and a pressure of 170 MPa (25,000 psi). In general, in the chemical industry creep is not a problem provided the wall temperature of vessels made of Ni—Cr—Mo steel is below 350°C. 

Fig. 2. MHD-steam power plant where HRSR is heat recovery seed recovery and the seed is an easily ionizable potassium salt. See text.

Parameter Conventional steam power plant MHD- Eady -Steam power plant Advanced... 

J. W. Pepper, Effect of Nitric Oxide Control on MHD-Steam Power Plant Economics andPeformance, SU-IPR Report No. 614, Institute for Plasma Research, Stanford University, Calif., Dec. 1974. 

Natural gas is the fuel of choice wherever it is available because of its clean burning and its competitive pricing as seen in Figure 1-30. Prices for Uranium, the fuel of nuclear power stations, and coal, the fuel of the steam power plants, have been stable over the years and have been the lowest. Environmental, safety concerns, high initial cost, and the long time from planning to production has hurt the nuclear and steam power industries. Whenever oil or natural gas is the fuel of choice, gas turbines and combined cycle plants are the power plant of choice as they convert the fuel into electricity very... 

More specifically, environment professionals in Dnepropetrovsk have offered a number of local CP projects. One of them is concerned with treatment of ash of the local steam power plant. According to Canadian experts, 32 elements may be recovered from the ash in addition to the residual coal, making the business of ash treatment highly profitable. 

The steam power plant should become another site for an exciting project enabling a 2-fold reduction in the degree of flue gas cleaning while cutting the electric power consumption by a factor of 2 to 3. The new process that applies pulsed voltage to the precipitation filters has been successfully introduced at several other plants in Ukraine. 

It is of special importance to the Lower Dnieper region where Pridneprovsk, Zaporizhia and Krivoi Rog steam power plants, Europe s biggest, are operated alongside with hundreds of smaller plants, cogeneration units and boilers. To abate pollution, one has to find its... 

A Chemistry Diagnostic System for Steam Power Plants... 

An example of this is a commercial central power station using a heat engine called a Rankine steam power plant. The Rankine heat engine... 

Why is the Carnot cycle not a realistic model for steam power plants ... 

COMMENTS The effect of increasing the boiler pressure on the quality of the steam at the exit of the turbine can be seen by comparing the two cases. The higher the boiler pressure, the higher the moisture content (or the lower the quality) at the exit of the turbine. Steam with qualities less than 90% at the exit of the turbine, cannot be tolerated in the operation of actual Rankine steam power plants. To increase steam quality at the exit of the turbine, superheating and reheating are used. 

Steam is generated in the boiler of a steam power plant operating on an ideal Rankine cycle at 10 MPa and 500° C at a steady rate of 80 kg/sec. The steam expands in the turbine to a pressure of 7.5 kPa. Determine (1) the quality of the steam at the turbine exit, (2) rate of heat rejection in the condenser, (3) the power delivered by the turbine, and (4) the cycle thermal efficiency (%). 

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