Vaporizing-gas drive

Vaporization of crude oil The lighter hydrocarbons are vaporized by the high pressure CO2 in a process analogous to a high pressure vaporizing gas drive. In this way, miscibility can be generated in the reservoir to provide an effective displacement of the crude oil. 

Fiydrothermal plants produce electric power at a cost competitive with the cost of power from fossil fuels. Besides generating electricity, hydrothermal energy is used directly to heat buildings. Across the United States, geothermal hot-water reservoirs are much more common than geothermal steam reservoirs. Most of the untapped hot-water reservoirs are in California, Nevada, Utah, and New Mexico. The temperatures of these reservoirs are not hot enough to drive steam turbines efficiently, but the water is used to boil a secondary fluid, such as butane, whose vapors then drive gas turbines. 

The Freeh two-step furnace, with separate control of the vaporization and atomization functions, represents a substantial improvement on commercial Massmann-type and THGA furnaces for interference-free analyses by ETA-AAS. However, it has the disadvantage that it relies on diffusion and convection to transport sample vapours from the cup vaporizer to the tube atomizer. Transport by purging is one solution to this shortcoming. For this purpose, the Massmann-type atomizer is heated to a steady-state atomization temperature and the THGA vaporizer is pulse-heated to have the purge gas drive the analyte from the vaporizer to the atomizer [21],... 

The vaporization of Th shares the problems of several of the early actinides, where the great stability of the monoxide gas drives the reaction... 

In the second stage nuclei grow into droplets. The driving potential for growth is the non-equilibrium between vapor and the new phase measured in terms of supersaturation. Therefore, growth ceases when conversion of vapor into liquid has reduced supersaturation to unity. The final state is a cloud of droplets suspended in the vapor/gas atmosphere. 

Introducing gas into the bowl also increases the vapor pressure driving force... 

If a warm vapor-gas mixture is contacted with cold liquid so that the humidity of the gas is greater than that at the gas-liquid interface, vapor will diffuse toward the liquid and the gas will be dehumidified. In addition, sensible heat can be transferred as a result of temperature differences within the system. For air-water-vapor mixtures (Le = 1) contacted with cold water, the methods of water cooling apply with only obvious modification. The operating line on the gas-enthalpy-liquid-temperature graph will be above the equilibrium curve, the driving force is H — H, and Eq. (7.54) can be used with this driving force. For all other systems, for which Le 1, the general methods below must be used. 

For the gas phase, energy transfers both as a result of a thermal driving force and as a by-product of vaporization. Thus,... 

LPG. LPG could be a principal alternative transportation fuel if its other uses were displaced by natural gas. A significant number of LPG fueling stations are located throughout the United States. LPG is a Hquid fuel and does not suffer the same driving range problem as natural gas. Because LPG vapor pressure is high, the storage tank has to withstand 2800 kPa (400 psi). 

D. Rectification in vertical wetted wall column with turbulent vapor flow, Johnstone and Pigford correlation =0.0.328(Wi) Wi P>vP 3000 < NL < 40,000, 0.5 < Ns. < 3 N=, v,.gi = gas velocity relative to R. liquid film = — in film -1 2 " [E] Use logarithmic mean driving force at two ends of column. Based on four systems with gas-side resistance only, = logarithmic mean partial pressure of nondiffusing species B in binary mixture. p = total pressure Modified form is used for structured packings (See Table 5-28-H). 

Example 6 Solvent Rate for Absorption Let us consider the absorption of acetone from air at atmospheric pressure into a stream of pure water fed to the top of a packed absorber at 25 C. The inlet gas at 35 C contains 2 percent by volume of acetone and is 70 percent saturated with water vapor (4 percent H2O by volume). The mole-fraction acetone in the exit gas is to be reduced to 1/400 of the inlet value, or 50 ppmv. For 100 kmol of feed-gas mixture, how many Idlomoles of fresh water should be fed to provide a positive-driving force throughout the pacldug How many transfer units will be needed according to the classical adiabatic method What is the estimated height of pacldug required if Hqq = 0.70 m ... 

Evaporators require a source of heat to operate. This heat may be supplied from a boiler, gas turbine, vapor compressor, other evaporator, or a combination of sources. Multiple effect evaporators are very popular when cheap, high pressure steam is available to heat the system. A Mechanical Vapor Recompression evaporator would use electricity or a gas turbine to drive a compressor that recycles the heat in the evaporator. 

Typically, the liquid out the bottom of the tower must meet a specified vapor pressure. The tower must be designed to maximize the molecules of intermediate components in the liquid without exceeding the vapor pressure specification. This is accomplished by driving the maximum number of molecules of methane and ethane out of the liquid and keeping a.s much of the heavier ends as possible from going out with the gas. 

An important variable that determines the size of a given desiccant bed is the relative saturation of the inlet gas. This variable is the driving force that affects the transfer of water to the adsorbent. If saturated gas (100% relative humidity) is being dried, higher useful capacities can be expected for most desiccants than when drying partially saturated gases. However, in most field gas dehydration installations the inlet gas is samrated with water vapor and this is not a variable that must be considered. 

The major mechanism of a vapor cloud explosion, the feedback in the interaction of combustion, flow, and turbulence, can be readily found in this mathematical model. The combustion rate, which is primarily determined by the turbulence properties, is a source term in the conservation equation for the fuel-mass fraction. The attendant energy release results in a distribution of internal energy which is described by the equation for conservation of energy. This internal energy distribution is translated into a pressure field which drives the flow field through momentum equations. The flow field acts as source term in the turbulence model, which results in a turbulent-flow structure. Finally, the turbulence properties, together with the composition, determine the rate of combustion. This completes the circle, the feedback in the process of turbulent, premixed combustion in gas explosions. The set of equations has been solved with various numerical methods e.g., SIMPLE (Patankar 1980) SOLA-ICE (Cloutman et al. 1976). 

The centrifugal compressor is well established for the compression of gases and vapors. It has proven its economy and uniqueness in many applications, particularly in which large volumes are handled at medium pressures. This compressor is particularly adaptable to steam turbine or other continuous speed change drives, as the two principles of operation and control are quite compatible. It is also adaptable to the electric motor, gas engine, and gas turbine with each installation being specific to a particular problem or process. Installation as well as operating costs can be quite reasonable. 

The overall driving force for mass transfer is AT = Pg—Pi, where Pi is the concentration of oxygen in the liquid phase expressed as an equivalent partial pressure. For the experimental conditions, T/ 0 due to the fast, liquid-phase reaction. The oxygen pressure on the gas side varies due to the liquid head. Assume that the pressure at the top of the tank was 1 atm. Then Tg = 0.975 atm since the vapor pressure of water at 20°C should be subtracted. At the bottom of the tank, 1.0635 atm. The logarithmic mean is appropriate AT =1.018 atm. Thus, the transfer rate was... 

---