Pressure reduction time

Case A sets a lower limit, case B an upper limit to the pressure reduction time and to the energy expenditure required during the second recovery step. The CO2 temperature will in reality lie above the saturation temperature at the given pressure, cf. Figure 12. 

PPG production planning and control PRT pressure reduction time... 

Among the measures which have successfully prevented metal dusting are the use of additives (steam, and compounds of S, As, Sb, and P) in the feed, reduction of pressure, reduction of temperature, and material change. The most common additives are sulfur compounds and steam. Susceptibility can be reduced by using a material in which the total percent of Cr plus two times the percent of Si is in excess of 22 percent. In some environments, a. small amount of a sulfur compound will stop the dusting. When sulfur compounds cannot be tolerated in the process stream, a combination of steam and an alloy with a Cr equivalent of over 22 percent may be most desirable. 

Moholkar et al. [11] studied the effect of operating parameters, viz. recovery pressure and time of recovery in the case of hydrodynamic cavitation reactors and the frequency and intensity of irradiation in the case of acoustic cavitation reactors, on the cavity behavior. From their study, it can be seen that the increase in the frequency of irradiation and reduction in the time of the pressure recovery result in an increment in the lifetime of the cavity, whereas amplitude of cavity oscillations increases with an increase in the intensity of ultrasonic irradiation and the recovery pressure and the rate of pressure recovery. Thus, it can be said that the intensity of ultrasound in the case of acoustic cavitation and the recovery pressure in the case of hydrodynamic cavitation are analogous to each other. Similarly, the frequency of the ultrasound and the time or rate of pressure recovery, are analogous to each other. Thus, it is clear that hydrodynamic cavitation can also be used for carrying out so called sonochemical transformations and the desired/sufficient cavitation intensities can be obtained using proper geometric and operating conditions. 

Some reduction of reflected overpressure results within a horizontal distance of about twice the barrier wall height. Beyond this distance, the effects of a barrier wail is virtually nil. Quantification of the pressure reduction is difficult and often times requires sophisticated computer modeling. Normally, it is more cost effective to upgrade the strength of the structure to be protected than it is to construct a barrier wall. This is especially true when the structure of interest does not have sufficient blast capacity in the roof to resist the blast load. 

Fig. 8. Effect of reduction time on conversion and hydrogenolytic behaviors. Catalyst, 10 wt % M0O3/AI2O3 calcined at 650°C for 3 hr and reduced at 450°C reaction temperature, 350°C WjF, 7.9 g catal hr/mole total pressure, 1 atm, H2/(2,5,3 -TrMeDPM + benzene) molar ratio, 2.0. [Data from Massoth (5S).]...

Pgnd p = 3 lO mbar. From these figures the corresponding time constants in the nomogram can be determined from there, the pump-down time tp can be found by calculating the pressure reduction R on the left side of column 5. The result is curve c in Fig. 2.77. 

Most studies of the effects of diuretics on serum lipids have lacked a placebo control to allow identification of time-dependent or environmental changes, or have been confounded intentionally or unknowingly by life-style interventions, including weight loss, diet, and exercise (347). The argument that the effects of diuretics on lipids may limit the beneficial effect of blood pressure reduction... 

For an adequate performance of the PIMMS it is necessary to install appropriate pressures and gas flows in the system, as well as a minimum time delay for the sample to reach the ionization chamber. The flow time of the sample gas governs the temporal resolution of the PIMMS measurements. Since the pressure of the plasma and sample gases are usually much higher at their origin than allowed in the plasma and the ionization chamber, respectively, there is a need for pressure reduction which will inevitably introduce a time delay. 

In spacecraft and similar closed-circuit fuel cell applications, partial pressure reductions are not a problem, other than for the production of waste-water. Therefore, constant supply pressure can be used, which greatly simplifies the control requirements, as the system becomes self-regulating on the demand side. In such applications, the waste can simply be blown down to a reservoir, based on time and current draw. 

One of the first to investigate the mathematical relationship between the vapor pressure reduction and the amount of solute was Francois Raoult. The mathematical relationship he determined is known as Raoult s law. What the law states is that the partial pressure of the solvent over a solution equals the vapor pressure of the pure solvent times the mole fraction of solvent in the solution. As Equation 10.4, this becomes... 

Breath-by-breath analysis of gases and volatiles is well known in medicine (1). The experimental techniques used, however, were not very well suited to our needs. For our purpose we needed a simple, reliable inlet system without extensive filtering and pressure reduction, but with a high sensitivity and short response times. 

This reaction is one of the most efficient catalytic processes in industrial chemistry, having an extremely short reaction time (lO s) and a high selectivity. The oxidation of ammonia benefits slightly from pressure reduction, since... 

The toxicity of coke for the metallic function was defined by its fouling effect on the reaction of cyclohexane dehydrogenation. For catalysts coked at high pressure, cyclohexane dehydrogenation was performed ex-situ with an initial reduction time of 8 h at 500°C. Preyious experience has shown that the reduction time (2 or 8 h) does not affect the actiyity of precoked catalysts. 

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