Interstage velocities

The effect of neglecting interstage velocities in modelling a real turbine stage the approximate equivalence of kinetic energy and enthalpy at nozzle inlet... 

Neglecting the interstage velocities implies putting cq, =0 for all I, so that equations (16.2) and (16.3) would then be reduced to... 

We may gain a further insight into the implications of neglecting the interstage velocities by using the concept of stagnation specific enthalpy introduced in Section 14.5. Writing /for., = Aq., -I- Cgj/2, equation (16.2) converts to ... 

But an accurate calculation of the performance of the nozzle requires a knowledge of both the stagnation and the local values of pressure. For example, the equation for mass flow for an impulse stage (e.g. equation (14.63)) will depend on the ratio pi.i/por.z. where the absence of a pressure drop over the blade implies p j = p2j = po.i+il unfortunately we will not have po.i+i available, only the value p oj+i, which will have to stand for bothpo.i+i and Por./+i- In fact, the assumption of zero interstage velocities means that we cannot distinguish between the stagnation and local values of any of the thermodynamic variables, and must be content with the approximations ... 

Fig. 9. Invariant cycling state temperature profiles for a three-stage, 800 mm diameter pilot plant S02 converter with interstage cooling. Profiles were measured just before switching of the flow direction and are for S02 at 7.6 vol% and a superficial velocity of 0.07 m/s. Catalyst was a commercial potassium-promoted vanadia, Type S101. (Figure adapted from Xiao and Yuan, 1996, with permission of the authors.)...

Temperature, T, affects both density and viscosity, increasing interphasc migration velocity. Installation downstream of the primary separator where 93% water removal typically occurs but upstream of any interstage or produced-water coolers provides the best performance. 

It is shown (Fig.3) a comparison of a model solution with the respective solids residence time distribution - the latter obtained by spectrophotometric registration of Ni-Al tracer concentration at the reactor outlet.From this and other curves generated by a computer it has been concluded that solids move essentially in backmixed flow,characterized by both liquid interstage backflow rates and solids settling velocities. 

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