Outlet riser

Since the tubes are 8 ft long, and allowing 7 ft for the exchanger head, pipe outlet riser, and one ell, a good first estimate for LF is... 

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. 

In a maximum of about 55 process tubes. The potential for fuel melting ifould be reduced by back-flow froip the pressurized outlet risers and by heat tSTansfer to adjacent coole precess and graphite cooling tubes. 

The bottom of the outlet risers are Joined to a flushing manifold which can he used during reactor outages for once-threugh. -tooling of t hs r-5a. tor, for reactor dccontaminatlcn, or for flushes after decontamination. Water from the flushing manifold may he sent to the same three points as water from the diversion system. 

The mixing manifold consists of seven parallel lines. Each line Is fed hy all 16 outlet risers and each of five of these lines conducts water hack to one of the five parallel loops. 

PRIMARY COOLANT CORE OUTLET RISER SECTION... 

The portion of the RCS within the N Reactor building consists of 16 parallel lines that conducted cooling water from an Inlet water manifold In the 109-N heat exchanger building to the reactor. Each of these 16 lines terminates in a vertical header that has 54 to 66 Individual pressure tube header-to-lnlet nozzle connectors attached. Similar outlet risers and parallel lines conducted the coolant from the pressure-tube-outlet nozzle-to-header connectors to an outlet water manifold (WHC 1989a). 

Vapor rises up through risers or up-takes into bubble cap, out through slots as bubbles into surrounding liquid on tray. Bubbling action effects contact. Liquid flows over caps, outlet weir and downcomer to tray below. Figures 8-63-67, 79, and 81. 

Risers are normally designed for an outlet vapor velocity of 50 ft/sec to 75 ft/sec (15.2 to 22.8 m/sec). The average hydrocarbon residence time is about two seconds (based on outlet conditions). As a consequence of the cracking reactions, a hydrogen-deficient material called coke is deposited on the catalyst, reducing catalyst activity. 

The regenerated catalyst supplies enough energy to heat the feed to the riser outlet temperature, to heat the combustion air to the flue gas temperature, to provide the endothermic heat of reaction, and to compensate for any heat losses to atmosphere. The source of this energy is the burning of coke produced from the reaction. 

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

ER E s RTD offering is principally similar to the Lummus design. In the ER E design, the riser cyclones are not hard-piped to the riser. However, the outlet of the riser-cyclones are directly connected to the inlet of the upper cyclones. 

To ensure proper drainage, inspection personnel must examine overhead piping for proper pitch. Sprinkler systems are designed to drain back to the sprinkler riser, where a 2 in (5.1 cm) valve drain outlet is provided. When this is not possible and some piping is trapped, supplementary low point drain valves should be provided. Low-point drains should be shown on the system drawings. 

Unit modifications that can improve the operation start with the riser and the feed injection system [6,7], The riser should be straight and have the desired velocities at both ends, which reduces excessive slip at the bottom and excessive erosion and turbulence at the outlet. A reduced diameter section is normally included at the lower end of the riser, just above the feed nozzles, to accelerate the feed/catalyst mixture. This improves contacting between the catalyst and hydrocarbons and minimizes back mixing of the catalyst. 

Post-riser quench can be used if a reactor vessel has a metallurgical limit and a higher riser outlet temperature is desired. Higher octanes and more alkylation feed may be the result. Improved vaporization of the feed could lower delta coke. 

The vapor-line riser pressure drop, including the vapor outlet nozzle loss. 

Elevation increase promotes subcooling. Once upon a time many years ago, a tragic event occurred in Louisiana. A rat entered the condenser outlet pipe shown in Fig. 13.4. The condenser had been off line for cleaning. The rat, having crawled up the riser pipe to the reflux drum, got its head stuck in the drum s inlet nozzle. Your author, unaware of the rodent s predicament, put the exchanger back into service. The condensed butane now flowed across the rat. The rat died. Well, we all must come to that end eventually, although perhaps not quite that exact end. Such is the way of all flesh. 

When operated in a horizontal mode, inlet and out let risers were located at SI and S2 to insure complete flooding of the adsorption bed. Septa at SI and S2 also provided access for inlet or outlet liquid samples that could be analyzed. When regeneration studies were being performed, an internal thermocouple was used to monitor the adsorption bed temperature and the dry nitrogen regeneration gas was passed through the bed by switching valve VI. 

Metals passivation also allows refiners to increase reactor severity to increase FCCU conversion. One refinery increased C4 production (valuable alkylation feed) 17.2% by increasing conversion with the injection of antimony. Another refiner was able to increase the FCCU riser outlet temperature 8°F through decreased dry gas production with metals passivation. Yield of gasoline increased, and gasoline RON clear increased 0.7. 

Intermediate liquid outlets. Liquid may be withdrawn using a chimney tray or from a downcomer. A chimney tray is a flat, unperforated plate with vapor risers. It permits total withdrawal of liquid a downcomer drawoff permits only partial withdrawal because some weeping occurs through the tray. A downcomer drawoff may contain some entrained gas, which must be separated downstream or allowed for in downstream equipment design. 

A typical example of a circulating fluidized-bed reactor model has been presented by Schocnfeldcr et al. [112, 116]. Its structure shown in Fig. 21 is based on the definition of four axial zones. Above the bottom zone the splash zone is located. It yields a mixing condition to link the bottom zone with the upper part of the reactor. Due to the internal backmixing this upper section is referred to as the recirculation zone. At the riser outlet, an exit zone on top of the recirculation zone yields a second boundary condition. Here, complete mixing is assumed. 

Figure 5 shows typical test facilities used by different investigators. In configuration, they all consist of a fast column or riser, a gas-solids separator, a downcomer for solids recycle, and a loop seal valve and/or an additional controlling device for adjusting solids circulation rate, mounted in positions appropriate with the inlet and outlet geometry. These facilities can be grouped into three types. 

Other designs use stiff connections between the tube outlet and the header. The M. W. Kellogg reformer, used in more than 140 reformers, uses the concept shown in Figure 43 [446], The tubes of each row are welded to a horizontal header located inside the fire box between the flue gas tunnels. With equal numbers of tubes on both sides, a central riser connects the tube harp to the water-cooled transfer line on the top of the firebox. The tubes are suspended by spring hangers. 

This was determined by injecting a tracer gas (CO2) into the two air inlets to the riser and measuring by means of an infra-red analyser the CO2 content of the outlet gas stream from the bubbling bed gasifier. Preliminary experiments showed there was no cross flow, V Boss, from the secondary air inlet into the gasifier, V sec, and no gas carried over from the downcomer. The gas ctoss flow was thus calculated solely on the basis of the flow into the gasifier, V g i, the flow into the primary air inlet, the... 

---