Partial volumes pressure vessel calculations

This chapter contains handy formulas for pressure vessels. Some of the formulas are from ASME, Section VIII, Division I 11], and others are associated formulations to calculate weights and partial fluid volumes. 

There are also handy pressure vessel formulas—calculation of head formulas with partial loaded volumes and head weights— included, making this a handy field guide. 

Before calculating the pressures, we must visualize the reaction vessel. The container s total volume is 5.00 L, but 0.150 L is occupied by the aqueous solution. This leaves 4.85 L for the gas mixture. The partial pressure of hydrogen is calculated using the ideal gas equation and assuming that no H2 remains in solution this is a good assumption because hydrogen gas is not very soluble in water ... 

For the semi-batch stirred tank reactor, the model was based on the following assumptions the reactor is well agitated, so no concentration differences appear in the bulk of the liquid gas-liquid and liquid-solid mass transfer resistances can prevail and finally, the liquid phase is in batch, while hydrogen is continuously fed into the reactor. The hydrogen pressure is maintained constant. The liquid and gas volumes inside the reactor vessel can be regarded as constant, since the changes of the fluid properties due to reaction are minor. The total pressure of the gas phase (P) as well as the reactor temperature were continuously monitored and stored on a PC. The partial pressure of hydrogen (pnz) was calculated from the vapour pressure of the solvent (pvp) obtained from Antoine s equation (pvpo) and Raoult s law ... 

We can calculate the volume of the vessel from the final given conditions plus the value of the partial pressure of the water vapor in the final state... 

At 600°C, a gas mixture of CO and CI2 is prepared that has initial partial pressures (before reaction) of 0.60 atm for CO and 1.10 atm for CI2. After the reaction mixture has reached equilibrium, the partial pressure of COCblg) at this temperature is measured to be 0.10 atm. Calculate the equilibrium constant for this reaction. The reaction is carried out in a vessel of fixed volume. 

In a certain experiment a student starts with 0.862 atm of N2 and 0.373 atm of H2 in a constant-volume vessel at 375°C. Calculate the partial pressures of all species when equilibrium is reached. 

Partial molar properties are defined for any property that has an extensive form for example, volume, enthalpy, etc. They are intensive properties and as such, they are functions of pressure, temperature, and mol fractions. To see how partial molar properties can be useful, consider the following thought experiment a vessels that contains a mixture (for example, a solution of several components) is poured into another vessel B. We will calculate the enthalpy in vessel B as it builds up during this process. The differential of is given bveq. fo.Sl the process obviously takes place under constant pressure and constant temperature, therefore, dT=o and dP = o. This simplifies the differential to the form. 

Liquid water and liquid benzene have very small mutual solubilities. Equilibria in the binary water-benzene system were investigated by Tucker, Lane, and Christian as follows. A known amount of distilled water was admitted to an evacuated, thermostatted vessel. Part of the water vaporized to form a vapor phase. Small, precisely measured volumes of liquid benzene were then added incrementally from the sample loop of a hquid-chromatography valve. The benzene distributed itself between the hquid and gaseous phases in the vessel. After each addition, the pressure was read with a precision pressure gauge. From the known amounts of water and benzene and the total pressure, the liquid composition and the partial pressure of the benzene were calculated. The fugacity of the benzene in the vapor phase was calculated from its partial pressure and the second viiial coefficient. 

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