Reaction volumetric

Baldwin and Mayor [25-29] studied H202 dissociation in reactors treated by boric acid (the common technique of reducing the contribution of heterogeneous dissociation). They found that the order of surface and volumetric reaction by H202 equals 1, and the rate constant at 713-833 K and M = N2 is the following ... 

In kinetically limited models, the pyrolysis rate is no longer calculated solely from a heat balance at the pyrolysis front. Instead, the rate at which the condensed-phase is volatilized depends on its temperature. This gives a local volumetric reaction rate (kg/m3-s) by assuming that all volatiles escape instantaneously to the exterior gas-phase with no internal resistance, the fuel mass flux is obtained by integrating this volumetric reaction rate in depth. One consequence is that the pyrolysis reaction is distributed spatially rather than confined to a thin front as with heat transfer limited models and the thickness of the pyrolysis front is controlled by decomposition kinetics and heat transfer rates. For a pyrolysis reaction with high activation energy or for very high heat transfer rates, the pyrolysis zone becomes thin, and kinetically limited models tend toward heat transfer limited models. 

Zqr coupling coefficient between chemical reaction and heat flow LSI coupling coefficient between chemical reaction and mass flow volumetric reaction rate m mass... 

Howard and Essenhigh [5] pyrolyzed coal particles, burning them in a one-dimensional plane-flame furnace. They measured the solid composition and the flame temperature along the axis of propagation. Particles attained a temperature of about 1100°C without ignition or significant devolatilization. They found that devolatilization of 0-200 p,m particles seems to be a volumetric reaction that is independent of particle size. 

The impact of biomass concentration on energy costs is substantial and clearly an optimum biomass concentration exists that maximizes volumetric reaction rate while minimizing the aeration costs. Most full-scale MBR plants aim to operate at a biomass concentration of between 10 and 15 g [38]. The average a value at typical MBR for municipal wastewater with an MLSS concentration of 12 kg m MLSS for municipal MBRs is about 0.6 [39]. A design value for a of 0.5 has been recommended [40]. 

Coulometric titrations have been developed for all types of volumetric reactions. Selected applications are described in this section. 

The final elements of the mass balances are the adsorption equilibria or the adsorption kinetics. According to Eqs. 6.5 and 6.6, adsorption and desorption steps are modeled as reactions with finite rate. The volumetric reaction rate based on the solid volume of all particles (Eq. 6.20) in the volume element is... 

For this reason each component element of a compound should be examined separately for analysis by one of the three basic types of volumetric reactions, namely acid/base, precipitation or redox analysis, as these represent a useful source of information on chemical reactions, familiar from laboratory practical work. 

It is possible to use solid catalysts in particulate forms in tubular reactors through the use of fluidised or fluid bed reactors, where the upward flow of the feed is sufficient to suspend the particulate catalyst in such a way that it seems to behave like a liquid (Figure 1.3). It is however preferable to use more structured catalysts, since better flow characteristics can be achieved, thus minimising hydrodynamic uncertainties and maximising volumetric reaction rates. 

The most challenging design has concerned a combustor for gas turbines [9,22]. In gas turbines, the adiabatic temperature is moderated by large excess air and the combustion intensity is in order of magnitudes higher than in furnaces, because of size constraints and, of course, because of pressure. Flameless oxidation has been sometimes described as volume combustion in contrast to surface combustion that hints to a turbulent flame front, where volumetric reaction rate is certainly much higher than in the former case. The basic question was then will a flameless oxidation system cope with the required... 

Subscript j is unnecessary when there is only one chemical reaction. When the kinetics are second-order, irreversible, and only a function of Ca, the dimensionless pseudo-volumetric reaction rate, based on bulk gas-phase concentrations, is... 

Assuming a constant-volume reaction (V = 0), the volumetric reaction rate is expressed as Equation (3.1.3-3a) ... 

In (5.37), r stands for the volumetric reaction rate, Ci represents the concentration of acid groups per unit volume of catalyst, and a, is the liquid-phase activity of component i. The temperature dependence of the reaction rate constant k can be expressed by the Arrhenius equation. All kinetic and thermodynamic parameters can be found elsewhere [7]. 

---