Pressure and gas composition

Table II summarizes the yields obtained from the CONGAS computer output variable study of the gas phase polymerization of propylene. The reactor is assumed to be a perfect backmix type. The base case for this comparison corresponds to the most active BASF TiC 3 operated at almost the same conditions used by Wisseroth, 80 C and 400 psig. Agitation speed is assumed to have no effect on yield provided there is sufficient mixing. The variable study is divided into two parts for discussion catalyst parameters and reactor conditions. The catalyst is characterized by kg , X, and d7. Percent solubles is not considered because there is presently so little kinetic data to describe this. The reactor conditions chosen for study are those that have some significant effect on the kinetics temperature, pressure, and gas composition.

In ex-situ measurements the catalyst is outside a proper reactor and it is in a state which is more or less different from the active state. The advantage is that we have a wide choice of temperature, pressure and gas composition. The disadvantage is that we don t really know how far the state is from the active state and we have no easy way of finding out. 

Figure 3 T)rpicai CSS solution of pressure and gas composition bed profiles for the Ot VSA process...

The application of Equations (13)-(20) is illustrated for binary mixtures of ethylene (1) and ethane (2) adsorbed on NaX zeolite (faujasite). The constants for the singlegas adsorption equations of state are given in Tables 1 and 2. The selectivity of NaX for ethylene relative to ethane is a function of temperature, pressure, and the composition of the gas. The selectivity at constant temperature (20 °C) is shown in Figure 3. The selectivity at the limit of zero pressure is the ratio of Henry s constants (Xi/X2=33.7). At constant mole fraction of ethylene in the gas, the selectivity decreases rapidly with increasing pressure. At constant pressure, the selectivity decreases with increasing mole fraction of ethylene in the gas. The selectivity at constant pressure and gas composition decreases with temperature, as shown in Figure 4. Decrease of the selectivity with temperature, pressure, and the mole fraction of the preferentially adsorbed species is typical behavior for binary adsorption. 

The infrared spectra were obtained using a commercial FTIR spectrometer (Mattson Centauri). The studies were performed in transmission mode, with the catalyst in the form of a pressed disc, using an environmental cell where the temperature, pressure, and gas composition could all be controlled [7]. All spectra were recorded at 4 cm resolution with the co-addition of 300 scans using an MCT detector. 

On behalf of KTI an experimental programme on these reactor concepts has been started at the University of Southern California (USC). Some of the experimental results, concerning the use of Knudsen diffusion membranes are available in the literature [32,40]. These data have been used to calculate the economics of an isothermal propane dehydrogenation membrane reactor concept and are compared with the commercial Oleflex and Catofin processes, based on an adiabatic concept. The experimental circumstances of these lab-scale experiments, especially residence time, pressures and gas composition are not the same as in commercial, large-scale processes. However, we do not expect these differences to have a great influence on the results of the work presented here. 

From what is known about the norm temperatures, it becomes clear which types of lines will be optimally excited in a plasma of a given temperature, electron pressure and gas composition, and the norm temperatures thus give important indications for line selection in a source of a given temperature. Atom lines often have their norm temperatures below 4000 K, especially when the analyte dilution in the plasma is high, whereas ion lines often reach 10000 K. Both types of lines are often denoted as soft and hard lines, respectively. 

Natural gas deviates from ideal behavior at increased pressures, but the deviation decreases at higher temperatures. Compressibility factors applicable to the deviation can be predicted at given temperatures and pressures if the composition is known. Gas gravity [(molecular weight of the sample/29) x density of air] is substituted for gas composition for gases that are almost free of nonhydrocarbon components. Gas viscosity can be predicted if the temperature, pressure, and gas composition are known. Viscosity of the natural gas decreases as the temperature decreases and increases as the gas gravity decreases. 

The rate data are reported at the temperature, pressure, and gas composition used by the authors. However, some authors have themselves converted their results to a given set of conditions, by means of activation energies and reaction orders that they consider appropriate. However, these parameters themselves may be structure sensitive, so that the results at the conditions actually used are of the most fundamental interest. 

Membrane processes, lika other unit operations, should be approached with a systematic design procedure supported by a solid data hese. Because of their neveity, Ibe del a hese for membrane processes is still mnch smaller lhan thei for corresponding older unit operations such as distillation. The current lack of information often necessitates the estimation and use of constant values for component permeabilities although thase coalficients are kaown to be functions of pressure and gas composition in many cases.28,29... 

Figure 11. Effects of pressure and gas composition on low-rate gasification in steam-hydrogen mixtures (1, 3)...

Measurements of are usually made at ambient conditions using simple gases such as N2, He, H2, and CO2. To predict for the same catalyst under reaction conditions, the effects of changes in temperature, pressure, and gas composition must be accounted for. One approach is to predict Dpore for the test gas (say. He) from Eqs. (4.5), (4.7), and (4.9) and to calculate r from Eq. (4.10) using measured values of and r. Then is predicted for the reactants at various reaction temperatures and pressures, and the same values of e and r are used to get from Eq. (4.10). The relative importance of Knudsen diffusion and bulk diffusion may change with reaction conditions, but and r should be constant. 

Thus the Knudsen diffusion coefficient is less strongly temperature sensitive than the free-space diffusion coefficient and, in particular, is independent of pressure and gas composition. 

High-temperature gas phase oxidation-corrosion data have been obtained for two exposures in the CONOCO COAL plant and one exposure in the HYGAS plant. Table VI summarizes the operating environments and in-plant times for these exposures. Since the pilot plants operate at variable temperatures, pressures, and gas compositions, weighted average values are given for the plant exposures. 

TG is based on continuous recording of mass changes of a sample of material, as a function of a combination of temperature with time, and additionally of pressure and gas composition. The TG curves reflect weight changes of coal sample in the process of coal oxidation caused by cod oxygen complex and various gases desorption and escape. 

The other consequence of the microcirculation is gob breathe. Gob breathe is described as periodical variation of air leakage volume, air pressure and gas composition in the gob. Evolution of relative air pressure attained from 1301 gob in Geting coal mine from February to March is presented in Table 1 where—stands air-in and -i-denotes air-out. 

Table 5 The effect of atmospheric pressure and gas composition on the apparent quantum requirement of photosynthesis In wheat leaves...

Among these mechanisms, viscous flow is non-selective while Knudsen diffusion is selective to smaller molecules. At high temperature, gas adsorption becomes weak and thus the surface diffusion and capillary condensation may be negligible. In fact, the perm-selectivity in micropo-rous membranes is a complex function of the temperature, pressure, and gas composition. Therefore, it is necessary to evaluate the perm-selectivity of the porous membranes using a gas mixture under similar operating conditions [3]. Table 2.2 gives an overview of the transport mechanisms in porous membranes. Note that the perm-selectivity is not always a key factor in MRs. 

It is easily altered for different pressures and gas compositions and temperatures. AU calculations are based on 1 kg mol of first catalyst bed feed gas. 

Power, target (sputtering) The power (watts) or power density (watts/cm ) applied to the sputtering target. This process variable, along with gas pressure and gas composition, are the parameters most often used to control the sputtering and sputter deposition processes. 

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