Chapter 3: Problem 5
In the energy balance, the change in potential energy is usually based on the gravity field; which other fields might be relevant as well and which terms would then appear?
Chapter 3: Problem 5
In the energy balance, the change in potential energy is usually based on the gravity field; which other fields might be relevant as well and which terms would then appear?
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Get started for freeAn anaerobic digester (see Chapter 14 for this technology) produces biogas at \(1.1\) bar (absolute) and \(25^{\circ} \mathrm{C}\). This gas, composed of 60 vol. \(\% \mathrm{CH}_{4}\) and 40 vol. \(\% \mathrm{CO}_{2}\), is to be compressed to 25 bar (absolute) before delivery to its end use; assume the compression to be isentropic and reversible. Calculate the temperature after compression.
Power company "E" in the Netherlands operates a fluidized bed combustion-based boiler with wood residues as fuel. The plant contains a simple steam turbine. The steam conditions at the inlet of the turbine are \(525^{\circ} \mathrm{C}\) and 100 bar. Assume that condensation of the steam takes place at a temperature of \(20^{\circ} \mathrm{C}\) and that isentropic expansion of steam occurs in the turbine. a. What is the specific power \(\left(\mathrm{kJ} \cdot \mathrm{kg}^{-1}\right)\) of the turbine expansion process? b. If the power plant generates \(25 \mathrm{MW}_{\mathrm{e}}\) and water pump work can be neglected, what is the mass flow rate of steam through the turbine? c. What assumptions have you made for these calculations?
What is the difference between the "degree of conversion" and the "relative degree of conversion" for a chemical reaction \(2 \mathrm{~A} \rightarrow \mathrm{B}\) ? What changes when the degree of conversion is expressed on a molar basis?
Using Equation (3.6), derive a material balance for a reactant in a closed system.
A steam boiler drum produces steam at a mass flow rate of \(64 \mathrm{~kg} \cdot \mathrm{s}^{-1}\) at 60 bar. This stream still contains \(2 \mathrm{wt} \%\) moisture. The feedwater from the economizer (a heat exchanger) is fed to the drum at a mass flow rate of \(62 \mathrm{~kg} \cdot \mathrm{s}^{-1}\). It contains \(3 \mathrm{ppm}_{\mathrm{w}}\) solids. Makeup water, containing \(50 \mathrm{ppm}_{\mathrm{w}}\) solids, is also fed into the drum at a mass flow rate of \(2 \mathrm{~kg} \cdot \mathrm{s}^{-1}\). Steam production is such that the solid content of the moisture leaving with the steam is \(5 \mathrm{ppm}_{\mathrm{w}}\). Blowdown, which is the release of hot liquid from the bottom of the drum, must keep the concentration of solids in the drum to \(1000 \mathrm{ppm}_{\mathrm{w}}\) - a. Calculate the blowdown requirement in \(\mathrm{kg} \cdot \mathrm{s}^{-1}\). b. Calculate the heat loss associated with blowdown in \(\mathrm{kW}\).
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