Gases and pressure

A gas ionization detector consists of a tube filled with a high pressure gas and two electrodes. A tube filled with 2 MPa (20 atm) of xenon is common. The gas in the tube ionizes when x-rays pass through the tube causing a current to flow between a high voltage potential placed across the electrodes. This concept is similar to that used in a Geiger tube detector. Gas ionization detectors are utilized in some CT scanners. 

Compounds pressure, gas, and heat when subjected to shock, pressure, high temperature or other energy sources excludes inert gases. 

Hydrocarbon releases in the petroleum industry are either gaseous, mists or liquids and are either atmospheric releases or pressurized. Gas and mist releases are considered more significant since they are readily ignitable since they are in the gas state and due to the generation of vapor clouds which if ignited are instantly destructive in a widespread nature versus liquid fires that may be less prone to ignition, generally localized and relatively controllable. 

A 150MW unit, built in 1954-60, exists at this site, fuelled by low-pressure gas and mazut. This unit is now due for decommissioning in the next 2-5 years. 

In the process (Figure 8-4), the feedstock is mixed with coal powder in a slurry mixing vessel, heated in the furnace and fed to the reactor where the feedstock undergoes thermal cracking reactions for several hours at a temperature higher than 400°C (750°F) and under pressure. Gas and distillate from the reactor... 

Typical utilities that the electrolysis systems need include electricity for other pe ripheral equipment cooling water for the hydrogen generation unit pre pressurization gas and instrumentation gas (Fig. 6). 

Allowable pfcssurc pressure drop is assmned to be about 5% of tbe absoUtfe pressure and (2) vciy viscous oiganics, where die allowabie pressure diop is assumed to be dbout I50-2S0 kNAn ... 

Drivers can be grouped according to the type of energy supplied - electrical, expansion of a high pressure gas, and expansion of a high pressure hquid. An inportant consideration in the selection of a driver is to match the speed of the driver with the speed of the machine. If it is necessary to run both units at different speeds for technical or economic reasons, then gears will be needed to increase or decrease the speed of the driver. Fans for many apphcations are V-belt driven. 

First we consider the impact of an explosion involving a high-pressure gas, and then we consider the explosion of a flashing liquid due to rapid depressurization. A primary characteristic of an explosion is that it is rapid, indeed so rapid that there is insufficient time for the transfer of heat or mass to or from the exploding material. Instead, the... 

As in the case of atom recombination, a convenient pressure scale to use across the entire range is the inverse of the binary diffusion coefficient, am, of reactant A in solvent M, as compared to density p in the low-pressure gas and the inverse of solvent viscosity t in liquid solution [46]. According to kinetic theory the diffusion coefficient in a dilute Lennard-Jones gas is given by... 

As a general observation, a solid solute increases the likelihood of forming an additional liquid phase for two reasons. Assuming the fluid phase is composed of the supercritical solvent and an ambient liquid, the solid solute acts as an impurity inducing a form of boiling point elevation higher pressures are needed in order to maintain a single fluid phase. Secondly, in this mixed fluid, the solid solute can melt more easily due to both the interaction with the pressurized gas and the liquid component present... 

A variety of polymers are extrusion-foamed, including polyolefins, polystyrene, and polyesters if the polymer is subjected to high-pressure gas, and the pressure is suddenly decreased or the temperature rapidly increased, the gas will try to escape from the polymer, causing antiplasticization. This rapid escape of gas can cause the nucleation and growth of bubbles within the polymer. Once a significant amount of gas escapes, the of the polymer drops, and thus the structure formed is frozen . 

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