Flapper plate

If we perform a moment balance about the hinge rings of a typical flapper valve plate, we can quantitatively predict the effect that the flapper plate... 

The first term accounts for the height the catalyst must back up above the bed in order to overcome the weight (more precisely, torque ) imposed by the flapper plate. 

Given A flapper valve of 41 cm is submerged 1.5 m in a fluidized bed of catalyst. The existing 1 cm thick flapper plate is experiencing erosion and a proposal has been made to replace the plate with a special hardened-steel plate having double the thickness. 

Determine the additional backup of dipleg catalyst that the much thicker and heavier flapper plate will produce. 

If we now recompute the submergence for the 2 cm thick flapper plate our new value for h becomes ... 

Obviously, the thickness of the flapper plate has a negligible impact on catalyst backup above within the dipleg. This is true despite the fact that the 2 cm flapper plate is computed to have a mass of 64 kg (141 pounds) Thus, irrespective of other influences, the pressure difference between the dilute phase of the vessel and the dilute phase of the dipleg almost always governs the distance that the dipleg solids back up above the bed level. This is one reason why we want to constrain the pressure drop across the cyclone system. Other reasons relate to erosion concerns that are associated with excessive cyclone velocities—hence, pressure drop—and the desire, in some operating units, not to reduce the pressure of the gas exiting the vessel any more than necessary. 

No trickle or flapper valves are used on the first stage. The riser cyclone diplegs terminate with a splash plate (Figure 9-4A). The upper reactor cyclone diplegs use conventional trickle valves. Sealing the upper reactor cyclone diplegs with about two feet of catalyst provides... 

Number of independent equations Number of degrees of freedom Number of independent variables Number of zeros of function Pressure upstream of nozzle in flapper/nozzle system Pressures applied to limbs of manometer tube or pressures downstream and upstream of orifice plate Distillation column pressure Pressure in feedback bellows of pneumatic controller Frictional drag per unit cross-sectional area of manometer tube... 

An integrated mixer/valve with a cantilever-plate flapper valve allows for non-continuous mixing by diffusion [49]. The mixer/valve consists of two wafers (i) a lower silicon wafer with a cantilever-plate flapper valve and fluid ports and (ii) an upper glass wafer that contains the fluidic channel. Initially the sample flows down the channel. When it is time to mix a reagent with the sample, the reagent is injected into the sample stream, and the two mix diffusively in a few seconds. After the desired section of sample is prepared, the reagent is shut off and the mixed... 

The basic consideration in the design of the flapper (membrane) valves, as shown schematically in Fig. 2.6a, is the ability to rapidly open and close the openings in the base plate according to the combustor operating frequency. Moreover, the valves must withstand the maximum pressure in the combustion chamber, yet open with only a small pressure difference. 

Fig. 11.1.4. Flapper-type underflow sealing valves featuring free-swinging hinged seal plates. Ducon type CA Trickle Valve (left) and type FA Trickle Valve (right). Courtesy Ducon Technologies Inc.

Fig. ll.B.l. Forces acting on a flapper valve plate submerged in a fluidized bed... 

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