Quenching secondary

The detector of choice for the efficient detection of 14-KeV y-rays is the gas proportional counter with a (mostly) krypton filling. (Methane, which we use, or carbon dioxide are typically added in a concentration of ca. 10% for quenching secondary discharges.)... 

The autoclave is not the only component of an LDPE plant which may be exposed to a decomposition. Local hot spots in a secondary compressor may initiate a decomposition reaction consequendy it is necessary to protect these units from serious overpressure by pressure relieving devices and to release the products of the decomposition reactions safely. The problem of the aerial decomposition referred to eadier has been largely overcome by rapidly quenching the decomposition products as they enter the vent stack. 

Hoechst WHP Process. The Hoechst WLP process uses an electric arc-heated hydrogen plasma at 3500—4000 K it was developed to industrial scale by Farbwerke Hoechst AG (8). Naphtha, or other Hquid hydrocarbon, is injected axially into the hot plasma and 60% of the feedstock is converted to acetylene, ethylene, hydrogen, soot, and other by-products in a residence time of 2—3 milliseconds Additional ethylene may be produced by a secondary injection of naphtha (Table 7, Case A), or by means of radial injection of the naphtha feed (Case B). The oil quenching also removes soot. 

The flame-space walls are stainless steel and are water cooled. No mechanical coke scraper is required. A water quench cools the cracked gas stream rapidly at the poiat of maximum acetyleae and this is followed by a secondary water quench. The primary quench poiat can be adjusted for variation ia throughput, to accommodate the depeadeace of acetyleae yield oa resideace time ia the flame space. 

A notable example of controlled water reuse was utilization of secondary sewage effluent from the Back River Wastewater Treatment Plant in Baltimore by the Sparrows Point Works of Bethlehem Steel (6). The Sparrows Point plant was suppHed primarily by weUs located near the brackish waters of Baltimore harbor. Increased draft on the weUs had led to saltwater intmsion. Water with chloride concentration as high as 10 mg/L is unsuitable for many steelmaking operations. Rollers, for example, are pitted by such waters. However, treated effluent from the Back River Plant can be used for some operations, such as coke quenching, and >4 x 10 m /d (10 gal/d) are piped 13 km to Sparrows Point. This arrangement has proved economical to both parties for >40 yr. 

This chapter presents a physical description of the interaction of flames with fluids in rotating vessels. It covers the interplay of the flame with viscous boundary layers, secondary flows, vorticity, and angular momentum and focuses on the changes in the flame speed and quenching. There is also a short discussion of issues requiring further studies, in particular Coriolis acceleration effects, which remain a totally unknown territory on the map of flame studies. 

We discovered a complementary procedure for conversion of OMen to other functional groups. The ester P-OMen bond was shown to be cleaved in a stereoselective manner reductively [85,86]. The cleavage takes place with almost complete preservation of stereochemical integrity at phosphorus. The reducing agents are usually sodium or Hthium naphthalenide, lithium biphenyUde, and Hthium 4,4 -di-fert-butylbiphenyl (LDBB). The species produced is then quenched with an alkyl hahde or methanol to afford tertiary or secondary phosphines, respectively (Scheme 5b). Overall, the displacement reaction proceeds with retention of configuration. 

P-Chirogenic diphosphine 19, which rhodium-chelate complex forms a seven-membered ring (rare case for P-stereogenic ligand), was also prepared in reasonable yield (68%) using the wide chemistry of secondary phosphine borane [37]. Deprotonation of the enantiomerically enriched ferf-butylmethylphos-phine-borane 88 (Scheme 15) followed by quenching with a,a -dichloro-o-xylene and recrystallization afforded optically active diphosphine-borane 89 (precursor of free phosphine 19). 

Secondary crystallization occurs most readily in polymers that have been quench-cooled. Quenched samples have low degrees of crystallinity and thus have relatively large volumes of amorphous material. A pre-requisite for secondary crystallization is that the amorphous regions must be in the rubbery amorphous state. Increased temperature accelerates the rate of secondary crystallization. The new volumes of crystallinity that form during secondary crystallization are generally quite small, amounting to less than 10% of the crystalline volume created during primary crystallization. 

---