Partial pressure reduction

The amount of hydrogen partial pressure reduction depends upon the materials and the relative thickness of the cladding/ weld overlay and the base metal—the thicker the stainless barrier is relative to the base metal the better.32 Archakov and Grebeshkova33 mathematically considered how stainless steel corrosion barrier layers increase resistance of carbon and low alloy steels to high temperature hydrogen attack. 

Displacement-Purge Cycle This cycle, which is somewhat similar to the previous one, differs from it in that a gas or vapor which adsorbs about as strongly as the adsorbate is used to remove the adsorbate (see Figure 1) Removal is thus facilitated both by adsorbate partial-pressure reduction in the fluid around the particles and by competitive adsorption of the displacement medium. As with the inert-purge cycle, the maximum delta loading is the equilibrium loading ... 

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. 

A purge-swing adsorption cycle is usually considered to be one in which desorption takes place at the same temperature and total pressure as adsorption. Desorption is accomplished either by partial-pressure reduction using an inert gas purge or by adsorbate displace-... 

The partial pressure of impurity, shown on the x-axis, is lowered by reducing the pressure on the adsorbent bed and purging the bed with high purity hydrogen. The first increment of partial pressure reduction from right to left on the x-axis is achieved by lowering the system pressure. The... 

Example 16-14. Fractionation of Gasoline and Kerosene. The crude oil shown in Fig. 16-27 is to be fractionated into gasoline, kerosene, and other products. The top five plates of the tower, which separate gasoline from kerosene, operate at an equivalent pressure of 1,000 mm including the partial-pressure reduction of steam. The gasoline is to have an end point of about 380°F, and the kerosene is to have a gravity of 46 API. 

---