Flash converter

Fig. 6. Flash smelting-flash converting process for continuous production of metallic copper. Courtesy of Keimecott Corp.

First, if the conversion time of an AD converter is less than the switching time of the S H circuit an added S H would decrease the performance of an AD converter. This could be the case with fast flash converters. 

Word-at-a-time conversion. This technique (flash converters) converts an analog input signal in a very short step (5 to 200 nsec) into digital form by comparing the input signal with all possible values at a time. Therefore a high number of comparators (2" 1, for a resolution of n bits) is needed to produce the result. As the number of comparators increases exponentially, this technique is limited to moderate resolution (typically 8 bit). 

Flash converters are mainly used in very fast measurement devices with low to medium requirements on resolution (e.g. digital sampling oscilloscopes or video digitizers). 

The significant types of ADC are flash-type converter, successive approximation-type, counter-type, sigma-delta converter, and integrating-type ADC. The sigma-delta converter and the integrating type ADC offer more accuracy and noise reduction than any other type ADCs, but they are very slow. The flash converter is the fastest of all... 

Outotec s LUREC process uses an SO3 gas recycle step to treat up to 25 volume% SO2 feed gas (Daum, 2009 Storch, 2J009). The LURECT process was first installed in 2007 at the Yanggu Xiangguang copper smelter acid plant which treats high SO2 concentration feed gas produced by a flash smelting and flash converting furnace. 

Coefficients for converting an ASTM D 86 curve to an atmospheric flash curve[ and an application for a petroleum cut whose standard specific gravity isl 0.746. ... 

Sodium Bicarbonate. Many soda ash plants convert a portion of their production to sodium bicarbonate [144-55-8], NaHCO. Soda ash is typically dissolved, carbonated, and cooled to crystallize sodium bicarbonate. The mother Hquor is heated and recycled. The soHd bicarbonate is dried in flash or tray driers, screened, and separated into various particle size ranges. Bicarbonate markets include food, pharmaceuticals, catde feed, and fire extinguishers. U.S. demand was approximately 320,000 t in 1989 world demand was estimated at one million metric tons. 

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical Hquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of Hquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quaHty transportation fuels, and to study Hquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

Reduction to Liquid Metal. Reduction to Hquid metal is the most common metal reduction process. It is preferred for metals of moderate melting point and low vapor pressure. Because most metallic compounds are fairly insoluble in molten metals, the separation of the Hquified metal from a sohd residue or from another Hquid phase of different density is usually complete and relatively simple. Because the product is in condensed form, the throughput per unit volume of reactor is high, and the number and si2e of the units is rninimi2ed. The common furnaces for production of Hquid metals are the blast furnace, the reverberatory furnace, the converter, the flash smelting furnace, and the electric-arc furnace (see Furnaces, electric). 

For environmental and economic reasons, the eady practice of roasting zinc sulfide and discharging the sulfur dioxide to the atmosphere gave way to plants where the sulfur dioxide is converted to sulfuric acid. Desulfurization takes place while the ore particles are suspended in hot gases. Called flash-and fluid-bed roasters, these processes are described below. Some plants use combinations of roasters and sintering for desulfurization. 

The conversion of small rings to smaller ones, without loss, is not common. 3-Chloroazetidine isomerizes reversibly to 2-chloromethylaziridine (Section 5.09.2.2.5). Flash vacuum pyrolysis can convert isoxazoles to azirines (Section 5.04.4.3). More common is the isomerization of medium-sized, i.e. five- or six-membered rings, e.g. certain succinimides (Scheme 23) (81JOC27) to azetidinediones, or bicyclic 1,2-dioxetanes to bis-oxiranes (Section 5.05.4.3.2). 

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