Third-stage

But for some liquids exists the third stage of liquid s penetration inside conical capillary, which was established in [5]. During this stage a channel is filling both from its entrance and from its closed top. Two liquid columns arise and are growing towards each other till the complete channel s filling (fig. 2). The most intriguing pattern can be observed when we exclude direct liquid s access to channel s entrance. It corresponds to the cases... 

The completion stage is identified by the fact that all the monomer has diffused into the growing polymer particles (disappearance of the monomer droplet) and reaction rate drops off precipitously. Because the free radicals that now initiate polymerization in the monomer-swollen latex particle can more readily attack unsaturation of polymer chains, the onset of gel is also characteristic of this third stage. To maintain desirable physical properties of the polymer formed, emulsion SBR is usually terminated just before or at the onset of this stage. 

To reduce catalyst losses even further, additional separation equipment external to the regenerator can be installed. Such equipment includes third-stage cyclones, electrostatic precipitators, and more recentiy the Shell multitube separator, which is Hcensed by the Shell Oil Co., UOP, and the M. W. Kellogg Co. The Shell separator removes an additional 70—80% of the catalyst fines leaving the first two cyclones. Such a third-stage separator essentially removes from the due gas stream all particles greater than 10 p.m (36). 

Table 3. Particle-Size Distribution from a Shell Third-Stage Separator ...

Dependable operation is critical. Second-stage or even third-stage cyclones may be used as backup. 

Specimen Location Main gas compressor third-stage cooler... 

The regenerator (Figure 4-80) is represented by a simplified model that ineludes the total volume and mass balanee ealeulation. The regenerator exit temperature is assumed eonstant for the duration of the transient. The third-stage separator is handled as a fixed volume and assoeiated pressure drop. Blow-down (bypass) flow is subtraeted from the input flow. 

As a first step in the driver analysis, the eapital required to make eaeh alternative operational is estimated. An orifiee ehamber is required to reduee the flue gas pressure for the steam turbine and motor alternatives. In this partieular ease, it is assumed that a third-stage separator is required for the power reeovery alternatives only and that an eleetrostatie preeipitator is used in all eases. Construetion and engineering are estimated as pereentages of total direet material and total material and eonstruetion, respeetively. An allowanee of 15% is made for eontingeney. Beeause the separator often ineludes a royalty fee, this item is added to the power reeovery alternates. As shown in Table 4-7, the motor alternative will require the least eapital. The power reeovery alternatives require additional eapital amounting to 4.63 and 4.75 per million respeetively. 

Several constraints were faced in the design phase of the project. For example, special attention was given to the fact that 400 Series stainless steel, carbon, and some grades of aluminum were not compatible with the process. Additionally, the expander discharge temperature was required to stay between 35-70°F. The operating rpm of the expander wheel was determined by the rpm required by the third stage of the air compressor. 

The main power source is a 2,200 kW rated motor, which drives two high-speed pinions through integral gears. The first stage of the compressor operates at 17,900 rpm, while the second and third stages operate at 21,800 rpm. The unit is controlled by a local control system, but operators can also monitor the operating parameters from the plant control room. 

Other suggestions that address gas flow deviation include a retrofit of the stator-nozzle assembly or replacing rotors with shorter blades. However, it is easier to increase volume flow by lowering inlet pressure. Increased capacity of the third-stage separator and the auxiliary equipment avoids the possibility that excess catalyst will pass through the equipment. 

The first and third stages involve substitution only whilst the second stage involves simultaneous addition and substitution. 

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