Great Purges

Used to summarize and detail the interrelationship of utilities such as air, water (various types), steam (various types), heat transfer mediums such as Dowtherm, process vents and purges, safety relief blow-down, etc., to the basic process. The amount of detail is often too great to combine on other sheets, so separate sheets are prepared. 

The great English herbalist Nicholas Culpepper (16161654) extolled elder by saying, "The juice of the leaves snuffed up into the nostrils purge the tunicles of the brain." In 1644, a book written by Dr. Martin Blockwich called Anatomie of the Elder was... 

Air (purge reduction) seals Air seals (also called purge reduction or gas seals) are often installed near the top of flare stacks. Others are located near the base of the flare. They are used to prevent air from entering the stack and are often recommended to prevent flashbacks and explosions. They also greatly reduce the amount of purge gas required. There are two basic types of air seals primarily used diffusion (sometimes called molecular or labyrinth seals) and velocity types. 

Let me tell you, in conclusion, that the bath in which the bridegroom is placed, must consist of two hostile kinds of matter, that purge and rectify each other by means of a continued struggle. For it is not good for the Eagle to build her nest on the summit of the Alps, because her young ones are thus in great... 

In his Natural and Moral History of the Indies, Father Jose de Acosta wrote in 1590 "The Creator hath furnished the West Indies with so great a treasure of silver, as all that which we reade of in antient Histories and that which is spoken of the mines of Spaine, and other provinces, is not comparable to that we see in those partes. The maner to purge and refine siluer [sic] which the Indians have vsed was by melting, in dissolving this masse of mettall by fire, which casts the earthly drosse aparte, and by his force separates silver from lead, tinne from copper, and other mettalls mixt. 

The recent availability of economical, stable and high-resolution pressure transducers has led to the development of a new type of helium pycnometer which offers extreme simplicity of operation along with great speed and accuracy. A schematic diagram of this pycnometer is shown in Fig. 21.1. The volume in the shaded area is considered the sample cell. After purging the system with helium and bringing all volumes to ambient pressure, the sample cell is pressurized to P2> about 15 psi above ambient. Valve is opened to connect the additional volume to that of the cell. 

In specialty metal processing such as titanium, the metal is milled with a dilute hydrofluoric acid bath. The bath must be purged of the titanium laden waste acid and replenished with fresh acid periodically. As in the stainless steel case, the titanium waste acid can be neutralized with KOH to precipitate out the metals. The fluoride recovery is greatly dependent upon good pH end point control. If pH is monitored carefully, a greater than 90% fluoride recovery can be achieved. 

B. Distillation and Purging. The great efficiency of fractional distillation for the removal of water from hydrocarbon and chlorocarbon solvents is often not well appreciated. The physical origin of this good separation is in part the large positive deviation of the water vapor pressure from Raoult s law because of the lack of affinity of water for these liquids. Typically, the distillation of a simple hydrocarbon solvent with a column of 100 plates and discarding the first two... 

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