Examples for Thermodynamic Diagrams

A vessel containing ethylene (C2H4) at 300 psia and 0 F is exposed to a fire in the process area. The temperature in the vessel is 600 F when the fire is extinguished. Estimate the final pressure in the vessel. 

Since the vessel size does not change appreciably, this situation maybe approximated by a constant volume process. Using the thermodynamic diagram, the initial volume is about 0.43 ft 3/lb. At this same volume and final temperature of 600 F, the pressure is  

A batch reactor is to contain 2,000 lb of ethylene (C2H4) at 1,000 psia and 200 F. Estimate the reactor 

Using the thermodynamic diagram, the volume is about 0.2 ft 3/lb of ethylene at these conditions. Substitution of this into the equation below for the reactor size provides  

A process vessel is to contain 300 lb of at 300 psia and 600 F. Estimate the process vessel size. 

Reactor Size = 12.000 Ibl (0.32 fr3/lbl = 640 ft 3 Example 3 - Process Vessel Size 

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The final temperature is read off directly from a thermodynamic diagram when that method is used for the compression calculation, as in Example 7.7. A temperature calculation is made in Example 7.10. Such determinations also are made by the general method for nonideal gases and mixtures as in Example 7.8 and for ideal gases in Example 7.4. 

The direct application of Eqs. (7.25) through (7.27) presumes the availabili of tables of data or an equivalent thermodynamic diagram for the fluid bei compressed. Where such information is not available, the generalized correlatio of Sec. 6.6 may be used in conjunction with Eqs. (6.62) and (6.63), exactly illustrated in Example 7.6 for an expansion process. 

Paths of various processes are conveniently traced on a thermodynamic diagram. For example, consider the operation of the boiler in a steam power plant. The initial state is liquid water at a temperature below its boiling point the final state is steam in the superheat region. As the water goes into the boiler and is heated, its temperature rises at constant pressure (line 1-2 in Figs. 6.2 and 6.3) until saturation is reached. From point 2 to point 3 the water vaporizes, the... 

Alloys represent special problems for -pH diagrams. Overlaying of the diagrams for the individual elements has shown some, albeit limited, promise (16). The problem may indicate that the effects of alloying are manifested more in the kinetics than in the thermodynamics of corrosion and electrochemistry. For example, passivity of pure iron in acid is not predicted from -pH diagrams it is a kinetic effect. 

Paths of processes are easily traced on a thermodynamic diagram. For example, consider the operationof the boilerin a steam powerplant. The initial state is liquid water at a temperature... 

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