Discharge riser

The riser tip must be at least as high as any part of the vessel or its overhead piping, to prevent discharge impingement. 

Multiple PR Valve Discharges to a Single Atmosphere Riser - Where two or more PR valves are manifolded into a single riser discharging to the atmosphere, the following additional requirements apply ... 

Application of this procedure to inadvertently ignited safety valve discharges can involve a special problem. Certain combinations of pressure ratio and length of safety valve riser can result in choked flow, with a pressure discontinuity at the exit. The pressure of the jet then adjusts to atmospheric pressure in a system of shock waves or expansion waves over a distance of a few pipe diameters. These waves can affect the local mixing of the jet with the crosswind. Since the calculation procedure incorporates correlations for subsonic jets, it cannot be expected to be entirely accurate in this case. Nevertheless, since the wave system... 

Riser Inlet Riser Outlet Blower Discharge Rcgen. Dense Phase Regen. Flue Gas Ambient... 

RTD s separate the catalyst and the oil vapor immediately at the end of the riser. The cyclone vapor usually discharges directly to the second-stage cyclones and then to the reactor vapor line. The catalyst is directly discharged into the stripper. The reactor is simply a vessel for holding the cyclones. Technologies are offered by ... 

Riser Cracking—Applied to fluid catalytic cracking units where the mixture of feed oil and hot catalyst is continuously fed into one end of a pipe (riser) and discharges at the other end where catalyst separation is accomplished after the discharge from the pipe. There is no dense phase bed through which the oil must pass because all the cracking occurs in the inlet pipe (riser). 

The riser cannot be considered as an isolated entity in the CFB loop. When no particles are introduced into or discharged from the loop, the solids mass flow rate in the riser is equal to that in the downcomer. For a given quantity of solids in the loop, the presence of fewer solids in the riser implies the presence of more solids in the downcomer. Likewise, the pressure drop across the riser must be balanced by that imposed by the flow through its accompanying components such as the downcomer and the recirculation device. Furthermore, the flow characteristics of the riser can be significantly affected by the behavior of the accompanying components in the loop. 

In the DCC unit, the hydrocarbon feed is dispersed with steam and cracked using a hot solid catalyst in a riser, and enters a fluidized bed reactor. A known injection system is employed to achieve the desired temperature and catalyst-to-oil contacting. This maximizes the selective catalytic reactions. The vaporized oil and catalyst flow up the riser to the reactor where the reaction conditions can be varied to complete the cracking process. The cyclones that are located in the top of the reactor effect the separation of the catalyst and the hydrocarbon vapor products. The steam and reaction products are discharged from the reactor vapor line and enter the main fractionator where further processing ensure the separation of the stream into valuable products. 

Back River treatment plant. As shown, the influent is introduced at the bottom of the tank. It then rises through the center riser pipe into the influent well. From the center influent well, the flow spreads out radially toward the rim of the clarifier. The clarified liquid is then collected into an effluent launder after passing through the effluent weir. The settled wastewater is then discharged as the effluent from the tank. 

The recycling of solids causes a spread in the residence time, and hence in the conversion of the particles as some rise only once through the riser while otha s are recycled several times. Partly unreacted feed can hence be discharged, causing insufficient conversion. It can be demonstrated (Smolders et al. [8]) that the conversion in the product stream (X a ), is equal to ... 

The drip tube/riser distributor is a variation of the orifice/riser device, with tubes added to the orifices to ensure close contact with the packing (not shown in Figure 12.55). When it is necessary that all tubes discharge evenly, a double tubesheet affair can be used with liquid under pressure pressure drop through the orifices and tubes must be estimated carefully for this arrangement. 

One important facet of the coolant flow is the submerged cooling provided by having the outlet risers go over the top of the reactor before being discharged into the downcomer. 

---