Mixer concentric

M 47] [M 48] [P 44] The current maximum flow rate of a small-scale interdigital concentric mixer (StarLam300) is 10001 h 1 at about 3 bar pressure drop [130], For the large-scale counterpart (StarLam3000) even 3000 1 h 1 at only 0.7 bar is determined. Extrapolating the flow rate-pressure relationship further to 10 bar yields a flow rate of nearly 2000 1 h 1 for the StarLam300 and nearly 10 000 1 h 1 for the... 

A principle behind the program is to keep the number of building blocks small. At this stage typical hardware included in the program are reactors, storage tanks, concentrators, mixers, splitters and filters. The development continues so more hardware will be included in the future. The specified hardware can be saved and reloaded from a database for future use. 

Non-gradient internal circulation reactor achieves high-speed circulation by the impeller of stirrer to promote gas flow in the reactor to obtain an ideal mixing in the reactor and to avoid the gradients of temperature and the concentration. Mixers are generally driven by magnetic to make dynamic seal become static seal, which is now more applicable. The performance of above main reactor is shown in Table 7.3. 

Static tube aerators are economically attractive and have a high transfer efficiency. They are weU-suited for lagoon appHcations. On the other hand, they are poor mixers and are not recommended for use when the sludge concentration is over 3000 mg/L. 

The natural process of bringing particles and polyelectrolytes together by Brownian motion, ie, perikinetic flocculation, often is assisted by orthokinetic flocculation which increases particle coUisions through the motion of the fluid and velocity gradients in the flow. This is the idea behind the use of in-line mixers or paddle-type flocculators in front of some separation equipment like gravity clarifiers. The rate of flocculation in clarifiers is also increased by recycling the floes to increase the rate of particle—particle coUisions through the increase in soUds concentration. 

Rubber-mill chips are dissolved similarly to resins, to provide color concentrates. Dough mixer and chip concentrates must be diluted with solvent and other vehicles to make finished inks. Media milling is becoming a method of choice in both flexo and gravure ink manufacturing. Other high speed dispersing units, such as the Morehouse, Cowles, Kady, and others, are also used. 

Air is compressed to modest pressures, typically 100 to 200 kPa ( 15-30 psig) with either a centrifugal or radial compressor, and mixed with superheated vaporized butane. Static mixers are normally employed to ensure good mixing. Butane concentrations are often limited to less than 1.7 mol 1 to stay below the lower flammable limit of butane (144). Operation of the reactor at butane concentrations below the flammable limit does not eliminate the requirement for combustion venting, and consequendy most processes use mpture disks on both the inlet and exit reactor heads. A dow diagram of the Huntsman fixed-bed maleic anhydride process is shown in Figure 1. 

Some studies (6) have been carried out to measure distribution of soHds in mixing tanks. Local soHds concentrations at various heights are measured at different impeller speeds. Typical data (Fig. 16) demonstrate that very high mixer speeds are needed to raise the soHds to high levels. At low levels, soHds concentration can exceed the average concentration at low mixer speeds. These soHds distributions depend on the impeller diameter, particle size, and physical properties. 

Anhydrous monocalcium phosphate, Ca(H2PObe made in a pan mixer from concentrated phosphoric acid and lime. The high heat of reaction furnishes essentially all the necessary thermal input and subsequent drying is minimized. A small amount of aluminum phosphate or a mixture of sodium and potassium phosphates is added in the form of proprietary stabilizers for coating the particles. Heat treatment converts the coating to a protective polyphosphate (19). 

Manufacture. Chlorinated TSP is made batchwise by addition of a 15% NaOCl solution containing some NaOH to a hot (75—80°C) concentrated Hquor consisting of di- and trisodium phosphates, in a mole ratio of about 1 10, in a suitable reactor, eg, a pan mixer (222). The mixture is allowed to cool slowly under constant agitation until crystallization occurs (62°C). When crystallization is complete, cooling is continued to about 45°C and the slightly moist crystals are air dried. Overdrying can result in decreased stabiHty. 

A similar process has been devised by the U.S. Bureau of Mines (8) for extraction of nickel and cobalt from United States laterites. The reduction temperature is lowered to 525°C and the hoi ding time for the reaction is 15 minutes. An ammoniacal leach is also employed, but oxidation is controlled, resulting in high extraction of nickel and cobalt into solution. Mixers and settlers are added to separate and concentrate the metals in solution. Organic strippers are used to selectively remove the metals from the solution. The metals are then removed from the strippers. In the case of cobalt, spent cobalt electrolyte is used to separate the metal-containing solution and the stripper. MetaUic cobalt is then recovered by electrolysis from the solution. Using this method, 92.7 wt % nickel and 91.4 wt % cobalt have been economically extracted from domestic laterites containing 0.73 wt % nickel and 0.2 wt % cobalt (8). 

Density. The difference in density between the two hquid phases in eqiiilibrium affects the countercurrent flow rates that can be achieved in extrac tion equipment as well as the coalescence rates. The density difference decreases to zero at a plait point, but in some systems it can become zero at an intermediate solute concentration (isopycnic, or twin-density tie line) and can invert the phases at higher concentrations. Differential types of extractors cannot cross such a solute concentration, but mixer-settlers can. 

Ga.s-Lic(uid Ma.s.s Tran.sfer Gas-liqiiid mass transfer norrnallv is correlated bv means of the mass-transfer coefficient K a ersiis powder le el at arioiis superficial gas elocities. The superficial gas clocitv is the ohirne of gas at the a erage temperature and pressure at the midpoint in the tank di ided bv the area of the essel. In order to obtain the partial-pressure dri ing force, an assumption must be made of the partial pressure in equilibrium wdth the concentration of gas in the liquid, Manv times this must be assumed, but if Fig, 18-26 is obtained in the pilot plant and the same assumption principle is used in e ahiating the mixer in the full-scale tank, the error from the assumption is limited. 

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