Jet impingement

Because the highest possible interfacial area is desired for the heterogeneous reaction mixture, advances have also been made in the techniques used for mixing the two reaction phases. Several jet impingement reactors have been developed that are especially suited for nitration reactions (14). The process boosts reaction rates and yields. It also reduces the formation of by-products such as mono-, di-, and trinitrophenol by 50%. First Chemical (Pascagoula, Mississippi) uses this process at its plant. Another technique is to atomize the reactant layers by pressure injection through an orifice nozzle into a reaction chamber (15). The technique uses pressures of typically 0.21—0.93 MPa (30—135 psi) and consistendy produces droplets less than 1 p.m in size. The process is economical to build and operate, is safe, and leads to a substantially pure product. 

FIG. 12-57 Special conveyor dryer with air jets impinging on surface of bed on first pass. Dried material is crushed and passed again through dryer, with air going through the now-permeable bed. [Chem. Eng., 192 (June 19, 1967).]... 

Fluidized-bed opposed-jet mills Hosokawa Micron Powder Systems Div.) differ from the Majac mill in that powder is not fed into the jets, but the jets impinge into a chamber mich contains suspended powder. The powder is entrained into the jets. This ehminates wear on the nozzles, and reduces contamination. Otherwise, construction and appheations are similar to the Majac mill. The fluidized-bed level is maintained a few inches above the jets. The Fluidized-bed mill is available in 13 sizes with air volumes ranging from. 50 to 11,000 mVh. One application is for toner grinding. 

When the width of the jet (calculated for free conditions) is less than the width of the room, airflow after jet impingement on a floor is similar to that in noncon-fined conditions. When the horizontally directed flow (along the particular line) reaches the wall, it is divided into two branches one following the direction of the branch with a maximum airflow and another flowing in the opposite direction. 

FIGURE 7.48 Schematic of inclined jet impingement with a floor surface. Reproduced from Zhi-... 

Details of jet impingement tests will be found in Section 19.1. Alloys resistant to impingement attack will be considered subsequently. 

Campbell points out that in evaluating condenser tube materials a test apparatus is required that will include all the principal hazards likely to be encountered in service and should thus cater for the following conditions impingement, slow moving water, heat transfer and shielded areas. Furthermore, the internal surfaces should not be abraded, as in the jet impingement test, but should be tested in the as-manufactured condition, particularly in view of the deleterious effect of carbon films produced during manufacture (see Sections 1.6 and 4.2). LaQue has pointed out the importance of specimen area in impingement tests... 

Fig. 2.4 Flow dynamics of normal jet impingement with an oscillating diaphragm. Reprinted from Lasance and Simons (2005) with permission...

Fig. 2.7 (a) Spray and jet impingement cooling. Reprinted from Lasance and Simons (2005) with permission, (b) Details of the test section, (c) HAGO nozzle and spray details. Parts (b reprinted from Fabbri et al. (2005) with permission... 

Static mixing catalysts Operation Monolithic reactors Microreactors Heat exchange reactors Supersonic gas/liquid reactor Jet-impingement reactor Rotating packed-bed reactor... 

The principle of operation of the impinging jet nozzle resembles that of the fan spray nozzle with the exception that two or more independent jets are caused to impinge in the atmosphere. In impact atomisers, one jet is caused to strike against a solid surface, and for two jets impinging at 180o(34), using SI units ... 

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