Acid velocity

Materials of Construction. Resistance of alloys to concentrated sulfuric acid corrosion iacreases with increasing chromium, molybdenum, copper, and siUcon content. The corrosiveness of sulfuric acid solutions is highly dependent on concentration, temperature, acid velocity, and acid impurities. An excellent summary is available (114). Good general discussions of materials of constmction used ia modem sulfuric acid plants may be found ia References 115 and 116. More detailed discussions are also available (117—121). For nickel-containing alloys Reference 122 is appropriate. An excellent compilation of the relatively scarce Hterature data on corrosion of alloys ia Hquid sulfur trioxide and oleum may be found ia Reference 122. 

A criterion for the position of the extent of the mesomerism of type 9 is given by the bond order of the CO bond, a first approximation to W hich can be obtained from the infrared spectrum (v C=0). Unfortunately, relatively little is known of the infrared spectra of amide anions. How-ever, it can be assumed that the mesomeric relationships in the anions 9 can also be deduced from the infrared spectra of the free amides (4), although, of course, the absolute participation of the canonical forms a and b in structures 4 and 9 is different. If Table I is considered from this point of view, the intimate relationship betw-een the position of the amide band 1 (v C=0) and the orientation (0 or N) of methylation of lactams by diazomethane is unmistakeable. Thus the behavior of a lactam tow ard diazomethane can be deduced from the acidity (velocity of reaction) and the C=0 stretching frequency (orientation of methylation). Three major regions can be differentiated (1) 1620-1680 cm h 0-methylation (2) 1680-1720 cm i, O- and A -methylation, w ith kinetic dependence and (3) 1730-1800 em , A -methylation, The factual material in Table I is... 

In common with any acidification the temperature, acid concentration, amount of acid, velocity of injection, viscosity of acid and fluid loss properties of formation have profound effects on the reaction rate. 

Amino Acid Velocity ((imol/mg Amino Add Velocity ( nmol/mg... 

A special feature of plate exchangers that requires some design attention is the possible acceleration of corrosion by the flow of the acid. Keeping the acid velocity low, at a level determined by the manufacturer, protects against such corrosion but reduces the acid-side film coefficient. The cooling water velocity should be sufficiently high to... 

Phosphoric Acid 75 185 85 - E - - 30 days approx., 726-793 tirs agitation — acid velocity 895 ft./min. 

Temperature, acid concentration, and acid velocity are three main factors that influence the corrosion rate of acid plant equipment. 

Corrosion rates generally increase with increasing acid velocity. An example is carbon steel which requires low temperatures (<38 °C) and low velocities of 0.3-0.9 m/s (DuPont, 2012) to ensure low corrosion rates in sulfuric acid service. 

An insoluble iron sulfate (FeS04) passive fihn forms on the surface of the carbon steel when in contact with sulfuric acid which minimizes corrosion (Eq. 30.1). High acid velocities break down the passive film exposing fresh metal to acid increasing corrosion. 

Stainless steels, such as 316L, can tolerate higher velocities up to 2.4 m/s. Polymers, such as Teflon , are not limited by acid velocity (DuPont, 2012). 

Acid velocity. Velocity has some effect on spending rate. In fracture... 

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