Oxidant-rich

The third key section of the process deals with ethylene oxide purification. In this section of the process, a variety of column sequences have been practiced. The scheme shown in Figure 2 is typical. The ethylene oxide-rich water streams from both the main and purge absorbers are combined, and after heat exchange are fed to the top section of a desorber where the absorbate is steam stripped. The lean water from the lower section of the desorber is virtually free of oxide, and is recirculated to the main and purge absorbers. The concentrated ethylene oxide vapor overhead is fed to the ensuing stripper for further purification. If the desorber is operated under vacuum, a compressor is required. 

A solid propellant is a mechanical (heterogeneous) or a chemical (homogeneous, or colloidal) mixture of solid-state fuel and oxidizer-rich chemicals. Specially-formed charges of solid propellant (grains) arc placed in the combustion chamber of the solid rocket motor (SRM) at a production facility. Once assembled, the engine does not require additional maintenance, making it simple, reliable and easy to use. 

There is an optimum fuel and oxidant flow rate to the flame, or, more precisely, an optimum fuel-oxidant flow rate ratio. If the flame is oxidant-rich, it is too cool. If it is fuel-rich, it is too hot. Again, monitoring the absorbance of an analyte standard while varying the flow rates helps to find the optimum ratio. Instrument manufacturers literature will also provide assistance. Safety issues relating to the proper flow rate of these gases will be addressed in Section 9.3.7. 

Molybdenum isotope variations appear to be on the order of 3.5%o in Mo/ Mo ratios, where the largest fractionation is seen between aqueous Mo in seawater and that incorporated in Fe-Mn crusts and nodules on the seafloor (Chapter 12 Anbar 2004). This isotopic contrast is interpreted to reflect fractionation by Mo sorption to Mn oxide-rich sediments relative to aqueous Mo. The 5 Mo values for euxinic sediments in turn are distinct from those of Fe-Mn crusts, highlighting the isotopic contrasts between major repositories of Mo in surface and near-surface environments. As discussed by Anbar (2004) in Chapter 12, a major focus of research on Mo isotopes has been the potential use as a paleoredox indicator in marine systems. 

Microscopically, the BIF is composed mainly of iron oxide rich bands that alternate with microcrystalline silica bands, quartz, chert and jasper. The ratios of these constituents are different from one sample to another. Occasionally, the samples contain sulfides, garnet and graphite. 

The rate of heat generation by a mixture depends on the mixture ratio of oxidizer and fuel components. As the mixture ratio becomes fuel-rich or oxidizer-rich, the rate of heat generation decreases, as does the reaction rate. At a certain mixture... 

Polymeric materials are used as binders to hold sohd particles together so as to formulate composite explosives or composite propellants. The polymeric materials also constitute part of the fuel ingredients when the crystalline particles are oxidizer-rich. Various types of hydrocarbon polymers are used as polymeric binders. 

Combustion Wave Structure of Oxidizer-Rich AP Propellants... 

Fig. 7.6 Burning rate versus (BDR) of oxidizer-rich AP-HTPB propellants at 3.5 MPa.

Fig. 7.7 Burning rate of an oxidizer-rich AP-HTPB propellant with the composition htpb(0 08) if low-pressure region.

Fig. 7.9 Heat flux and heat of reaction in the gas phase and in the condensed phase for an oxidizer-rich AP-HTPB propellant at low pressures below 0.1 M Pa.

When large spherical AP particles dg = 3 mm) are added, large flamelets are formed in the dark zone.Pl Close inspection of the AP particles at the burning surface reveals that a transparent bluish flame of low luminosity is formed above each AP particle. These are ammonia/perchloric acid flames, the products of which are oxidizer-rich, as are also observed for AP composite propellants at low pressures, as shown in Fig. 7.5. The bluish flame is generated a short distance from the AP particle and has a temperature of up to 1300 K. Surrounding the bluish flame, a yellowish luminous flame stream is formed. This yellowish flame is produced by in-terdiffusion of the gaseous decomposition products of the AP and the double-base matrix. Since the decomposition gas of the base matrix is fuel-rich and the temperature in the dark zone is about 1500 K, the interdiffusion of the products of the AP and the matrix shifts the relative amounts towards the stoichiometric ratio, resulting in increased reaction rate and flame temperature. The flame structure of an AP-CMDB propellant is illustrated in Fig. 8.1. 

Table 9.3 shows the measured detonation velocities and densities of various types of energetic explosive materials based on the data in Refs. [9-11]. The detonation velocity at the CJ point is computed by means of Eq. (9.7). The detonation velocity increases with increasing density, as does the heat of explosion. Ammonium ni-trate(AN) is an oxidizer-rich material and its adiabatic flame temperature is low compared with that of other materials. Thus, the detonation velocity is low and hence the detonation pressure at the CJ point is low compared with that of other energetic materials. However, when AN particles are mixed with a fuel component, the detonation velocity increases. On the other hand, when HMX or RDX is mixed with a fuel component, the detonation velocity decreases because HMX and RDX are stoichiometrically balanced materials and the incorporation of fuel components decreases their adiabatic flame temperatures. 

When AP particles are added to GAP-AN pyrolants, a number of luminous flame-lets are formed above the burning surface. These flamelets are produced as a result of diffusional mixing between the oxidizer-rich gaseous decomposition products of the AP particles and the fuel-rich gaseous decomposition products of the GAP-AN pyrolants. Thus, the temperature profile in the gas phase increases irregularly due to the formation of non-homogeneous diffusional flamelets. 

Ammonium nitrate (AN) is a crystalline oxidizer that produces an oxidizer-rich gas when thermally decomposed according to ... 

The antimicrobial activity of piperitone oxide rich Mentha rotundifolia M. suaveolens) oil was investigated by Oumzil et al., who found it less significant than that of pulegone or piperitone rich oils. The biosynthesis of the two levorotatory diastereomers from (15,25)(+)-piperitenone oxide... 

Some fountain compositions tend to be oxidant-rich due to the presence of excess potassium nitrate or sometimes various oxalates. The reason for this is to reduce the burning rate and/or to enhance the visual effects. Certainly if gunpowder is considered to be a mixture of fuels (charcoal and sulfur) and oxidant (potassium nitrate) then the maximum rate of burning should coincide with a slightly under-oxidised system. The burning rate is therefore reduced by adding excess nitrate to the system. 

A number of clays are layered silicate-like materials. Most clays contain finely divided quartz, micas, and feldspars. Iron oxide-rich clays are employed to make pottery and terracotta articles. Clays containing iron oxide and sand are used to make bricks and tiles. Clays rich in calcium and magnesium carbonate are known as marls and are used in the cement industry (Section 12.2). 

Payne, T.E. Waite, T.D. (1991) Surface com-plexation modeling of uranium sorption data obtained by isotopic exchange techniques. Radiochim. Acta 52-53 (Pt 2) 487-493 Peacock, M.A. (1942) On goethite and lepidocro-cite. Trans. Roy. Soc. Ca. 36 107-119 Peacock, S. Rimmer, D.L. (2000) The suitability of an iron oxide-rich gypsum by-product as a soil amendment. J. Environ. Qual. 29 1969-1975... 

Hybrid Rocket Propellants. A special proplnt combination of unlike materials, particularly of unlike physical characteristics. Typical hybrid proplnt combinations are a solid fuel (or oxidizer) in combination with a liquid oxidizer (or fuel) in tjiat order. Sometimes a grain of solid fuel is encased in the combustion chamber of a rocket engine and burned in combination with liq oxygen. Similarly, a liq fuel may be injected into a combustion chamber in contact with a solid oxidizer. Another example is the use of concentrated hydrogen peroxide and a hydrocarbon fuel. In this case, the hydrogen peroxide is converted by decompn into a hot gas contg oxygen. The fuel is injected downstream of the first reaction, mixed with the hot oxidizer-rich gas, and burns (Ref 1)... 

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