Sources Annular

Because indirect-heat calciners frequently require close-fitting gas seals, it is customaiy to support aU parts on a selFcontained frame, for sizes up to approximately 2 m in diameter. The furnace can employ elec tric heating elements or oil and/or gas burners as the heat source for the process. The hardware would be zoned down the length of the furnace to match the heat requirements of the process. Process control is normaUy by shell temperature, measured by thermocouples or radiation pyrometers. When a special gas atmosphere must be maintained inside the cyhnder, positive rotaiy gas se s, with one or more pressurized and purged annular chambers, are employed. The diaphragm-type seal ABB Raymond (Bartlett-Snow TM) is suitable for pressures up to 5 cm of water, with no detectable leakage. 

In high heat flux (heat transfer rate per unit area) boilers, such as power water tube (WT) boilers, the continued and more rapid convection of a steam bubble-water mixture away from the source of heat (bubbly flow), results in a gradual thinning of the water film at the heat-transfer surface. A point is eventually reached at which most of the flow is principally steam (but still contains entrained water droplets) and surface evaporation occurs. Flow patterns include intermediate flow (churn flow), annular flow, and mist flow (droplet flow). These various steam flow patterns are forms of convective boiling. 

Then, 11 m3 (70 barrels) of 15 /, HC1 were pumped downhole through a coil tubing. The bottomhole pressure history is in this case precisely derived from surface data, since the latter are collected in the open annular space between the coil tubing and the casing. No computation of friction pressure drops all along the injection string is needed, which removes a major source of errors in the derivation of bottomhole data. The bottomhole pressure is just equal to the sum of the surface... 

Figure 4. Ion source and reaction chamber for ion-molecule equilibria. Solution to be electrosprayed flows through elestrospray capillary ESC at 1 -2 pL/min. Spray and ions enter pressure reduction capillary PRC and emerge into forechamber FCH maintained at 10 torr by pump PL. Ions in gas jet, which exits PRC, drift towards interface plate IN under influence of drift field imposed between FCH and IN. Ions enter the reaction chamber RCH through an orifice in IN and can react with reagents in the reagent gas mixture RG. This flows into RCH and out of RCH to FCH where it is pumped away. Ions leaking out of RCH through orifice OR are detected with a mass spectrometer. To reduce the inflow of solvent vapors into the pressure reduction capillary PRC, a stream of dry air is directed through the pipe Al, at 60 L/min, and pure N2 is directed at SG into the annular space at the entrance of the pressure reduction capillary, PRC. From Klassen, J. S. Blades, A. T. Kebarle, P. J. Phys. Chem. 1995, 99, 1509, with permission.

Blowout preventers (BOPs) function is to cut off the flow of potential blowout. In all wells being drilled there are normally three holes or pipes within pipes that are at the surface of the wellhead -conductor pipe, casing pipe, and drill pipe. The drill pipe is the actual hole while the outer two are annulus formed around the inner pipe. Any one of these under varying conditions can be a source of through which oil or gas can escape during drilling. The annular preventer is a valve that appears... 

Figure 8.1 Schematic diagram of electron impact (El) source for mass spectrometry. The sample enters the evacuated chamber as a gas and is intersected by a beam of electrons released from the heated cathode and accelerated towards the positive anode at the top. The impact of the electrons atomizes and ionizes the sample, and the resulting positive ions are attracted towards the annular cathode on the right, passing through it and out of the source towards the mass selection device.

It is sometimes argued that - by reciprocity - STEM and HRTEM can perform similar tasks since a STEM can be thought of as a HRTEM with detector and electron source being exchanged if the detector is a point detector on the optical axis . Indeed, bright field -and annular dark field imaging can be executed in either a STEM or a HRTEM as shown for the latter in Figure 4. ... 

For this purpose, the flow tube emptied directly into a high-pressure ion source. This source was essentially a sealed box with a gas inlet for the Cl reagent gas, a 0.58 mm hole to allow injection of a magnetically collimated electron beam, and a 0.99 mm hole to allow ions to exit into the mass spectrometer. The flow tube was coupled to the source using a 0.1 mm annular gap that thermally isolates the source from the flow tube, but allows little of the gas flow to escape. Even at a flow tube temperature of 1000 K, the source temperature increased no more than 50 K. To avoid any variations in source conditions with flow tube temperature, the source was thermostated to a constant temperature of 100 K. 

Packed Beds. Data on liquid systems using a steady point source of tracer and measurement of a concentration profile have been obtained by Bernard and Wilhelm (B6), Jacques and Vermeulen (Jl), Latinen (L4), and Prausnitz (P9). Blackwell (B16) used the method of sampling from an annular region with the use of Eq. (62). Hartman et al. (H6) used a bed of ion-exchange resin through which a solution of one kind of ion flowed and another was steadily injected at a point source. After steady state conditions were attained, the flows were stopped and the total amount of injected ion determined. The radial dispersion coefficients can be determined from this information without having to measure detailed concentration profiles. 

Three-dimensional ion traps that operate on the principle of the quadrupole are another type of mass analyser (with or without a DC component). In ion traps, the ions are confined between the electrodes which have a particular shape that resembles the set-up of a quadrupole. Although they are physically simple devices, the fundamental principle of ion traps is very complex and they are more sensitive yet less expensive than quadrupoles. The volume determined by the so-called annular, superior and inferior electrodes is simultaneously the ion source and the mass-filter (see Fig. 16.12). Ion traps are usually coupled to separation techniques (GC/ MS, LC/MS). 

The mode of operation of an ion trap can be described in the following way the ions are generated in the central part of the filter by electron ionisation using a short electron pulse. A radiofrequency voltage is then applied to the annular electrode, which confines the ions in the source where they follow complex trajectories in the presence of a low helium pressure of about 0.01 Pa. The mass spectrum is obtained by increasing the radiofrequency amplitude, which destabilises ions of increasing mass. The increase in voltage causes the ions to increase the amplitude of their... 

S. Greenfield, Invention of the Annular Inductively Coupled Plasma as a Spectroscopic Source, J. Chem. Ed 2000, 77, 584. 

If the size of the production unit requires higher radiant power than can be provided, for technical reasons, by one lamp, clusters of light sources may be installed, which, consequently will alter the diameter or the height of the inner core of, for example, an annular photochemical reactor. However, following the check list of concepts (vide supra), optimal reaction conditions will in most cases limit the size of the photochemical reactor, and the planned rate of production may require several reactor units installed in a parallel mode (batch process) or in series (continuous process). 

Extended light sources may be installed around a tubular reactor or in the axis of an annular irradiated reaction volume. In the first case, an annular (or coaxial) radiation field focalized on the axis of the tubular reactor is created (Figure 10), and, in reaction mixtures of very low absorbance, irradiance as a function of the radius of the cylindrical reactor shows highest values in the axis of the reactor (positive geometry of irradiation, Figure 11 [2,3]). 

The extended light source may also be placed at the axis of a reactor composed of two coaxial cylindrical tubes (Figure 12). The emitted radiant power is absorbed by the reaction system contained in the annular reactor volume. Irradiance diminishes in a filled reactor with increasing radius (Eq. 36), this geometry is called the negative geometry of irradiation [2,3]. 

In sensitized or photocatalyzed reactions, conditions of total or constant absorbance can easily be controlled by the concentration of the sensitizer or photocatalyst added. In addition, experience has shown that the concept of spatial separation between the light source and the reaction mixture is in general not required. Dragoco uses immersion-type annular reactor geometries [2, 3, 69, 70] for the production of ( —)-rose oxide by rose bengal sensitized oxidation of (— )-citronellol (Eqs. 45-48, Figure 23). 

Equations (79) and (80) describe the radiant exitance at any point in space and originating from the total volume of the light source. By using geometrical concepts to describe a radiation field in an empty annular reactor (Figure 30), integration limits for the spherical coordinates (p, , fi) are given by Eqs. (81)-(84). 

The measurement of FPN from the N03 recovered from a backup Teflon-nylon or nylon filter with the ADM is subject to some of the same potential sources of error as with the DDM. No loss of FPN passing through the annular denuder is expected on the basis of particle-loss measurements (55). Although HONO is efficiently removed ahead of the filter or filters, nearly all of the PAN would reach the nylon filter. Retention of PAN on nylon filters has been reported to be insignificant. Thus, relatively little error in FPN is expected with the ADM and CO -glycerol coated denuders. 

The efficiency of HN03 collection with a single annular denuder should be confirmed by each user with a known source of HN03, regardless of denuder coating used. On the basis of laboratory studies, Ferm and Sjodin (42) reported a technique that can be used to correct simultaneously for penetration of HN03 through the first of tandem denuders as well as for artifact N03" due to atmospheric species retained with low efficiency. 

Solution. Assume an infinite plane containing m point sources per unit area each of strength m. The plane is located in the (y,z) plane at x = 0. All the point sources in the plane lying within a thin annular ring of radius r and thickness dr centered on the x-axis will contribute a concentration at the point P located along the x-axis at a distance, x, given by... 

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