Stabilization techniques

Oil Burners The structure of an oil flame is shown in Fig. 27-28, and Fig. 27-29 illustrates a conventional circiilar oil burner for use in boilers. A combination of stabilization techniques is used, typically including swirl. It is important to match the droplet trajectories to the combustion aerodynamics of a given burner to ensure stable ignition and good turndown performance. 

OsB (5), and one can only find estimates of the potential energy surface around Esa (6 = 0) by stabilization techniques [48]. 

Stability may be inherent or induced. In the latter case, the original system is in a condition of metastable or neutral eouilibrium. External influences which induce instability in a dispersion on standing are changes in temperature, volume, concentration, chemical composition, and sediment volume. Applied external influences consist of shear, introduction of a third component, and compaction of the sediment. Interfacial energy between solid and liquid must be minimized, if a dispersion is to be truly stable. Two complementary stabilizing techniques are ionic and steric protection of the dispersed phase. The most fruitful approach to the prediction of physical stability is by electrical methods. Sediment volumes bear a close relation to repulsion of particles for each other. 

There are six stabilization techniques currently available however, only two of them have found widespread application. These are cementation and stabilization through the addition of lime and fly ash.25 26 There is currently developmental work being undertaken to make use of bitumen, paraffin, and polymeric materials to reduce the degree to which metals can be taken into solution. Encapsulation with inert materials is also under development. 

New computational approaches are developed to explore flame stabilization techniques in subsonic ramjets. The primary focus is statistical modeling of turbulent combustion and derivation of the adequate boundary conditions at open boundaries. The mechanism of flame stabilization and blow-off in ramjet burners is discussed. The criterion of flame stability based on the clearly defined characteristic residence and reaction times is suggested and validated by numerical simulations. 

The present study is to elaborate on the computational approaches to explore flame stabilization techniques in subsonic ramjets, and to control combustion both passively and actively. The primary focus is on statistical models of turbulent combustion, in particular, the Presumed Probability Density Function (PPDF) method and the Pressure-Coupled Joint Velocity-Scalar Probability Density Function (PC JVS PDF) method [23, 24]. 

One of the problems in combustors that utilize premixed flames is the attainment of stable performance over an extended range of operation (turndown ratio). The condition, at which the combustion wave is driven back causing the flame to be extinguished when the flow velocity exceeds the burning velocity everywhere in the flow field, is of particular interest to this study. The physical mechanisms responsible for the blow-out limits and flame stabilization of jet flames is still a topic of extensive research [1, 2]. The flame stabilization technique discussed in this paper is aimed to control the velocity gradient in the region close to... 

The results presented above clearly demonstrate the merits of the counter-current shear layer control as a flame stabilization technique. With the use of the high-resolution PIV, the near flame structure is measured with sufficient detail to obtain the velocity gradients with accuracy. Prom these measurements, it is observed that the transverse velocity gradient dU /dr assumes large values at the nozzle exit as compared to that of laminar premixed Bunsen burner flames. 

The U.S. Department of Energy (DOE) is researching technologies for the stabilization and immobilization of fly ash contaminated with radionuclides and metals that will reduce waste material volume and consistently satisfy regulatory requirements. The Mixed Waste Focus Area (MWFA), a DOE/EM-50 program, has stated the need for improved stabilization methods that would accept higher ash waste loadings. To address these issues, the MWFA has invested in a sintered ceramic stabilization technique developed by Clemson University. 

At Kirtland Air Force Base in New Mexico, an in situ application of MAECTITE was used to treat 2000 yd of soil contaminated with lead and cadmium. Following MAECTITE treatment, leachable lead and cadmium levels in soils were less than residential human health standards. In addition, contaminant levels were low enough that the treated waste could be categorized as nonhazardous by Resource Conservation and Recovery Act (RCRA) standards. Total costs for the project were 125,000, which was almost 40% less than alternative stabilization techniques considered at the site (D21483F, p. 3). 

WASTECH processing does not destroy wastes it is a stabilization technique. According to the vendor, results vary according to the contaminant treated. 

Photocorrosion can be prevented by adding a redox couple to the electrolyte whose potential is more favourable than the decomposition potential such that the redox reaction occurs preferentially. When n-CdS is used as photoanode in aqueous electrolytes, the electrode is photocorroded since the reaction, CdS -1- 2h - S -1- Cd, occurs readily. By adding NaOH and sodium polysuphide to the electrolyte (Ellis et al, 1976), photocorrosion is prevented. The /S redox couple preferentially scavenges the photoholes. At the anode, sulphide is oxidized to polysulphide (free sulphur) and free sulphur is reduced back at the dark cathode. Similarly n-Si anodes have been stabilized by using a nonaqueous electrolyte containing a ferricinium/ferrocene redox couple (Legg et al, 1977 Chao et al, 1983). Unfortunately, a similar stabilization technique cannot be applied to photoelectrolysis cells. Some examples of electrode... 

The conventional tartaric stabilization techniques applied in the wine industry are based on two opposite principles. One is aimed at heightening HT- and T2- precipitation by reducing wine temperature and leads to the so-called cold stabilization technique. To accelerate nucleation, wines are seeded with exogenous KHT crystals, cooled and kept at —4°C for 4-8 days... 

Any applied use of the simple heat stabilization technique to wood will be limited by the large loss in abrasion resistance and toughness. 

While this is a very positive boundary condition for the development of low-dose formulations, the major drawback of the low-dose formulation range is, as mentioned earlier, the potential exacerbation of chemical instability of active pharmaceutical ingredients. Thus, stabilization techniques are of high interest to the formulator dealing with this formulation space. Specifically, stabilizers from various classes of antioxidants have been applied.23,24 It is obvious that the specific knowledge of potential and actual degradation pathways of the drug will be crucial for the development of stable formulations. 

In conclusion we presented an absolute frequency measurement and a frequency comparison of two iodine stabilized frequency-doubled Nd YAG laser systems, one set up at the Institute of Laser Physics, Novosibirsk, Russia, the other at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. The individual frequency stability and the reproducibility of the two laser systems were characterized. It was found that despite fundamental differences as far as frequency generation, signal detection and frequency stabilization techniques are concerned the combined frequency reproducibility of the two laser systems was better than 1.5 0.7 kHz. In a further experiment the absolute frequencies of HFS components of the R(56)32-0 and P(54)32-0 transitions in I2 were determined using a phase-coherent frequency chain. This chain links the frequency of the -stabilized Nd YAG laser to a CH4-stabilized He-Ne laser at 3.39 pm. The He-Ne reference was calibrated before the measurement against an atomic... 

Various types of cement and pozzolanas (e.g., coal burning fly ash, lime, blastfurnace slag and similar materials) are mostly used as the stabilizing matrix. That stabilization technique is used for the immobilization of inorganic or organic waste. 

Deactivation of light naphtha aromatization catalyst based on zeolite was studied, by kinetic analysis, micropore volume analysis and model reactions. Coke accumulates at the entrance of zeolite channel, blocks it and hinders reactant molecule to access active sites in zeolite channel. Our own stabilization technique passivates coke-forming sites at the external surface of the zeolite. This minimizes the coke formation at the entrance of zeolite channel and increases on-stream stability. The stabilized catalyst enabled us to develop a new light naphtha aromatization process using an idle heavy naphtha reformer that is replaced by CCR process. 

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