Volumetric speed

An optimized relationship is obtained between the beU jar, 60° swing-leaf valve, LN trap, baffle for the oil, and the plane of action for the diffusion pump (DP) top jet. The valve open area equals 0.38 of the cross-sectional area of the inside diameter of the furnace. The volumetric speed factor for water vapor is thus 0.38 x 0.9 crr 0.34, where 0.9 is the Clausing factor. 

In (2) following designations are accepted T - temperature of a gas mix x and r - longitudinal and radial coordinates w - linear speed of a gas mix c,- and cpi - molar concentration and a thermal capacity of i-th component of a gas mix Aa and Ar - longitudinal and radial effective factors of heat conductivity AH - formal thermal effect of reaction (1) (T) - volumetric speed of reaction (1) Vj -stoichiometric factor of i-th component. 

It is consequent from (1.30) that heat removal efficiency is in inverse proportion to rector radius at constant linear speed V or in direct proportion at constant volumetric speed w of reaction mixture flow (productivity). That is one should increase R maintaining apparatus productivity approximately constant and trying to improve external heat removal. However at that reagents concentrations and temperature gradients appear (torch regime is formed) otherwise flow regime transforms from turbulent into laminar. Mentioned factors limit the radius of tubular turbulent reactor from the top [1, 60]. 

Distribution curves of reagents residence times are converged with mixing Tr to the low values region while volumetric speed of reagents w increases (Fig. 3.9) for all considered tubular turbulent apparatus constructions (Table 2.2). 

A more suitable and modern approach in coimection with chemistry applications is that of smoothly cutting-in a Roots vacuum pump in to a process without relying on a bypass valve but instead by using a frequency and thus speed controlled motor. Now the Roots vacuum pump wUl no longer start to operate at a certain operating pressure at full speed. Under certain circumstances it may be started even at atmospheric pressure, but under speed, respectively frequency control, and at a lower rotational speed and thus a low theoretical volumetric speed. The characteristic is the same as for a Roots vacuum pump equipped with a bypass valve, except that now the valve can no longer fail because it is missing. 

The volumetric speed of a single-zone reaction is the speed of the reaction per unit of volume (the areal speed will be used for 2D zones). We emphasize that this notion is only defined for reactions with a single reaction zone, which includes all homogeneous reactions, in other words that occur entirely in one phase ... 

The volumetric speed (areal speed) is thus expressed in moles per second and m (moles per second and m ). This magnitude is a priori based on the extent of the reaction (among others like temperature, concentration of the reactants, etc.) and therefore time, but is independent of the volume (or the surface) of the zone. 

Expression of the volumetric speed (areal) from variations in the amount of a component... 

Expression of volumetric speed according to variations in concentration in a closed system... 

This relationship is extremely useful for the computation of the volumetric speed of a reaction from concentration measurements in a closed system. 

The volumetric speed, which is the difference in the reactivities of both opposite reactions, is also called reactivity. Since it is obvious that the reactions take place in the same area, the global reactivity is ... 

In the case of a homogeneous reaction, since all the steps take place in the same zone - they have the same space function - a simple relationship between the volumetric speed and the reactivities of elementaiy steps is obtained by taking into account [1.12] ... 

It should be noted that if we change the component by substituting A with B, the equivalent of the previous relationship would not necessarily involve the same steps in the sum, nor the same coefficients. This would mean that there are several volumetric speeds depending on the component chosen to define it, which contradicts relation [1.3]. We will return to this problem in Chapters 6 and 7. 

This is a simple relationship by which to calculate a volumetric speed where we know the reactivity of a single elementary step. 

We thus obtain a volumetric speed that is proportional to nitrogen pentoxide concentration as if the overall reaction [2.R4] was elementaiy, except that the coefficient k is not a rate coefficient and does not follow Arrhenius law since constants kik and k2, which are rate coefficients, follow it. However if ... 

By including this in [5.29] and [5.32], the volumetric speed of hydrogen bromide formation is obtained nsing ... 

To illustrate this, we apply this method to hydrogen bromide synthesis for which the volumetric speed-concentration relation is relation [7.54], which will be written as follows ... 

In systems with concentrations that are held constant, the speeds with constant space function - which is the term ( ) of product isothermal conditions. This is true for the volumetric speed of a homogeneous system as well as for the areal speed of a catalytic system. This will be also true in the case of a strictly heterogeneous reaction that obeys the law of < E. Space functions are, however, frequently a function of time, which leads to absolute speeds or to rates that vaiy with time through this space function. 

This reactivity j is a volumetric speed in a homogeneous reaction. In the case... 

This property applies to all homogeneous systems in pseudo-steady state modes. Here, the function c ) is the volumetric speed and the unique space function is the ratio of the phase volume to the amount of reference substance chosen. 

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