Injection tubing

Fig. 18. Jet trajectory of a round jet in bounded cross flow where J = Pj V j p (a) flow geometry, ratio of height of tunnel to diameter of injection tube HID) = 12 and (b) flow streamlines where the data points are experimental deterrninations and the lines correspond to calculated predictions for (—)...

In ESMS (Figure 11.2), a dilute solution of the analyte is pumped through the capillary at a flow rate of typically 0.1 to lOpl/min. A high voltage (typically 2-5 kV) is applied to a narrow bore sample injection tube (capillary) relative to its surrounding, which generally includes a counter electrode that is... 

Figure 3 Scheme of the apparatus for measurement of PCL. 1, Vessel for irradiation of a photosensitizer-containing solution 2, UV lamp 3, shutter 4, injection tube 5, peristaltic pump 6, measuring cell 7, photomultiplier 8, computer. (From Ref. 45.)... 

Injection into unsaturated deposits must also consider that when the injected water leaves the injection tubing, it is at atmospheric pressure, and the driving head is lost which lowers injection efficiency. In addition, the capillary and surface tension forces in the void spaces provide resistance to water movement, thus limiting injection efficiency. Injection into only the saturated zone (Figure 8.8b) maintains a positive head pressure on the water until it exits the well screen. This limits the chemical reaction that might occur in the well bore. Since the void spaces are saturated, there are no capillary or surface tension forces to overcome. 

Bischoff and Levenspiel (B14) considered this problem, and have presented design charts which allow estimation of errors in the calculated dispersion coefficients for various conditions. It was found that when the ratio of injection to tube diameter is less than 20%, or e < 0.2, then the assumption of a point source, or e-> 0, was good to within 5%. Thus for many cases, the neglect of the finite size of injection tube is justified. 

Now if we have data of C/Cj. as a function of pipe radius, r, we can use standard least-squares techniques to estimate Ko, Ki, K, . In addition, we can find the standard deviations of the estimates of Ki by the least-squares procedure, which gives an indication of the precision of the data. The first constant, Ko, should be unity if we have a perfect mass balance, and the deviation from this value gives an estimate of the reliability of the data. Knowing the injection tube size, we can find the Ni/q from the least squares K from Eq. (59). 

For the modification of a 4-mm MAS NMR probe, an injection tube with an outer diameter of 1 mm is used, and the hole in the rotor cap has an inner diameter of 1.4 mm. This 4-mm CF MAS NMR probe reaches sample spinning frequencies of 12 kHz and is suitable for the investigations of atoms in the framework of solid catalysts, such as Na, Al, and nuclei. Approximately 50 mg of catalyst powder can fit in the rotor reactor of a 4-mm CF MAS NMR probe. 

A disadvantage of CF MAS NMR probes with injection tubes is that these systems are not gas tight at the outlet in the rotor cap. Hence, they are limited to catalytic investigations at atmospheric pressure. On the other hand, because pure... 

Data reported in the paper by Li and Chyu (2003) show that the thickness of the PEN area does not depend on the cell length. On the contrary, the diameter varies linearly with the length. An advantage of this practice is a volume reduction in the case of small cells. Moreover, it is possible to keep about the same operating conditions, independently of the cell length. Figure 7.2 shows the Reynolds number inside the cell with and without the injection tube. The active area is ... 

If the current density and the gas utilization are assumed as constant, the mass flow rate per unit active area is constant. Without injection tube, the gas velocity does not depend on the cell length ... 

When the injection tube is used, it is possible to choose its diameter so that the Reynolds number is about constant in the air channels. A similar consideration can... 

Generally, the flow field is assumed as a laminar flow, due to the relatively low velocities that the air reaches inside the cell. Nevertheless, Campanari and Iora (2004) performed a fluid dynamic calculation of the flow in the air injection tube and in the annular section of the cell the results indicated a transition from laminar to turbulent flow the values of the Reynolds number found were in some cases above 1000, whereas the transition between laminar and turbulent flow is stated to be in the range between Re = 750 and Re = 2700. The regime of the flow affects the heat exchange between the gas and the solid material and the diffusion of chemical species. Li and Suzuki (2004) too performed similar calculations and found values of the Reynolds number that were consistent with a regime transition in the air injection tube, but not for the annular section (Re = 385 with a velocity lower than 7.82 m/s). Li and Chyu (2003) state that the assumption of laminar flow is to be rejected. Other researchers, such as Haynes and Wepfer (2001) previously and Stiller et al. (2005) later, assume laminar flow. 

The starting powders were fed with a PRAXAIR powder feeder through an injection probe to the top of the plasma flame by argon carrier gas (3 lmin-1) with a constant feed rate of 10 g min-1. The outlet of the quartz injection tube of an inner diameter of 2 mm, was located 10 mm below the top of the induction coil. 

Injection is started in an empty mould when the final rotational speed of 20.000 rpm is reached. The movement of the injection tube is controlled by a commercial stepmotor system, this to ensure a smooth and reproducible movement of the injector tube. A typical axial... 

Also the NO released with the disproportionation of nitrite calls for special measures to avoid emission. The environmental problems and the lack of accurate control of the course of the pH level with time has led to the development of an additional deposition-precipitation method, namely the injection procedure. It has been observed that injection of an alkaline solution through a tube ending below the surface of the suspension of the support, avoids locally high concentrations. The reason is that high shear stresses can be established around the end of the injection tube, which is not possible at the surface of the suspension. The... 

In order to overcome these problems, a number of investigators have developed rapid-injection reactors. In such systems, coal and/or catalyst are injected into the reactor once the gas and liquid reactants are heated to the desired reaction temperature. The coal and/or catalyst may be mixed with liquid reactant (to form a slurry) and preheated to an allowable temperature where significant reaction does not occur before injecting into the reactor. This minimizes the amount of the coal and/or catalyst left in the injection tube... 

The rapid-injection reactor is particularly suitable for applications involving catalysts that require specific pretreatment procedures. For example, in applications with catalysts requiring presulfiding, the catalyst treatment can be undertaken in the injection tube. Upon completion of pretreatment, the injection tube can be attached to the reactor and the contents added to the reactor when desired. 

Method I Flow System. Monomer is fed in from the liquid monomer through an injection tube placed in the center of the reaction tube while the system was pumping. 

Figure 1. Artisfs drawing of an inductively coupled plasma, (a) Induction coily (b) coolant argon, (c) sample aerosol injection tube.

Sample aerosol is transported to the plasma with an argon-gas stream (1 L/min) and is injected into the central channel of the plasma through the aerosol-injection tube of the plasma torch. The sample material is rapidly vaporized, atomized, and excited as it passes through the surrounding, higher-temperature region of the plasma. 

Also, the insertion of solvents — particularly into plasmas — causes a number of spectral interferences and, at dissolved solid concentrations above ca. 1%, signal suppression and salt build-up on the nebulizer, the interface or the injection tube of the torch. 

In-situ leaching in the seams themselves proceeds with sulfuric acid or carbonate solutions. The leaching agent is fed in via injection tubes into the rock seam and brought to the surface via a central tube. In situ uranium leaching efficiency is 60 to 85%. Currently ca. 5000 t of uranium are extracted in this way. 

Solids are pulverized in a Wiley laboratory knife-blade mill to less than 1 mm in size. These solids are then metered into a 1.3-cm OD stainless steel injection tube by a screw feeder. The speed of the screw feeder is variable between 0-400 rpm. The solids are mixed with process air in the injection tube. The solids-air mixture comes out of the end of the 1.3-cm OD tube and into the annulus of a 3.7-cm ID alumina tube. This alumina tube extends to within 1.3 cm of the bottom of the 15-cm ID alumina containment vessel. During normal operation of the reactor, the depth of the molten salt expands from a quiescent level of 15 cm to an expanded depth of about 30 cm. 

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