Riser pipes

Balancing Valve Hand or mechanically operated valve installed in each riser pipe of a multicell tower to control water flow. 

Self-Supporting Stack - This type of unit is designed so that the flare riser pipe has no lateral strucmral support. For short flares, this type is the least expensive to erect and maintain. 

A marine riser must be held in tension to prevent the riser from collapsing under its own weight. This can be accomplished by adding buoyant material to the riser pipe, or by mechanical tensioning devices (Figures 4-498, 4-499). Tensioning devices are usually required in water depths greater than 250 ft. 

In the long term (20-40 years), the overall domestic HW system is subject to pinhole leaks stemming from the galvanic corrosion of steel riser pipes (usually located in inaccessible areas), with resultant flooding within the building. Galvanic corrosion develops because these systems typically contain a wide range of mixed metals such as black... 

To install the screen and riser piping, the drilling equipment extends the borehole to the approximate desired depth of the bottom of the screen. Short sections of screen and/or riser pipe can be assembled above ground. A cap or plug (also with Aush joint threads) is commonly added to the bottom of the lowest section to prevent the enAy of formation materials. Precautions should be taken to keep the sections free of... 

Once the grout materials have cured (dependent on grout composition and site conditions, but commonly approximately 24 h), a locking protective cover is installed in concrete over the top of the riser pipe. A concrete pad is commonly installed around the protective cover with its upper surface sloped away from the cover to shed precipitation and/or surface water (Figure 1). 

After the silica flour or soil mixture has set, add a layer of silica sand as a filter pack, then fill the remainder of the borehole with bentonite or a grout seal (Figure 5). Access lines may be run from the lysimeter reservoir through a protective PVC riser pipe to the land surface. A locking protective casing should be used to secure the abovegrade lysimeter components. If the lysimeter is used immediately after installation, it is necessary to purge any water used to prepare the siiica flour or soil slurry. Remove at least the water volume equivalent to approximately one third of that used to make slurry. 

A well point system consists of several individual well points spaced at 0.6 m to 1.8 m intervals along a specified alignment. A well point is a well screen (length 0.5 to 1.0 m) with a conical steel drive point at bottom. Individual well points are attached to a riser pipe (diameter 2.5 to 7.5 cm) and connected to a header pipe (diameter 15 to 20 cm). At the midpoint, the header pipe is connected to a centrifugal pump. As yield at different well points may vary, a valve at the top of each riser pipe is used to control the drawdown so that the screen bottom is exposed. The pump provides 6 to 7.5 m of suction, but friction losses reduce the effective suction to 4.5 to 5.4 m. 

An example of a basic environmental test bed would be a temperature controlled tank of a liquid, perhaps sea water. This basic structure is applicable to a considerable range of products and can involve acceleration by using more severe conditions than in service. In one use of such a rig, the insulation on oil riser pipes is tested by circulating hot oil through the pipe whilst it is immersed in the tank. 

Filtration is achieved bv adsorption within the pores in the media. The oil droplets coalesce into larger drops and after the bed reaches oil saturation the coalesced oil passes upward through the riser pipes with the water. 

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. 

The boiler shown in Fig. 15.2 relies on natural circulation. The density difference between the water plus steam in the downflow pipes and the riser pipes causes the water to circulate through the pipes. A typi-... 

Temporary circulation pumps are often necessary, as permanently installed pumps may be unsuitable or unable to provide the velocity necessary for flushing and cleaning work. Typically the water velocity necessary is 6 to 9 ft/sec (2 to 3 m/sec). Once in motion, debris velocity is virtually independent of particle size, but is clearly a function of water velocity. Relatively high velocities are needed to lift particles up from horizontal pipe surfaces and dirt pockets (dirt collection points at the base of riser pipes), and especially to overcome problems of particle retardation when moving from the horizontal through a vertically upward bend. Special provisions may need to be made to ensure the cleaning of dead-leg areas,... 

Back mixing the phenomenon observed when a catalyst travels at a slower rate in the riser pipe than the vapors. 

RCC process a process for the conversion of heavy feedstocks in the riser pipe (q.v.). 

Riser pipe the pipe in a fluid catalytic cracking process (q.v.) where catalyst and feedstock arc lifted into the reactor the pipe in which most of the reaction takes place or is initiated. 

S W fluid catalytic cracking process a process in which the heavy feedstock (q.v.) is injected into a stabilized, upward flowing catalyst stream whereupon the feedstock-stream-catalyst mixture travels up the riser pipe (q.v.) and is separated by a high efficiency inertial separator from which the product vapor goes overhead to fractionation. 

While at first sight the installation shown in Figure 6.28 seems reasonable, we can see that the size of the inlet riser piping is smaller than the SRV inlet size, which will lead to excessive pressure drop once the valve opens. The valve will chatter and be damaged or even destroyed prematurely. The valve will also not flow its rated capacity and is therefore a hazard. 

Catalyst falling to the bottom of the separator is passed by an airlift to a regenerator unit. Here, the air burns carbon deposited on the catalyst and reheats the catalyst before its return to the riser pipe. In some systems, and to prevent overheating in the regenerator, the oxidation of carbon proceeds only to carbon monoxide and carbon monoxide combustion to carbon dioxide occurs in a second regenerator. 

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. 

Af is again the sum of the actual resistances of the reboiler plus the downcomer and riser pipe plus the inlet and outlet losses at the vessel and exchanger. 

Fig. 12.5 Experiment illustrating osmotic pressure. The riser pipe on the left serves as manometer.

With the help of a carrot and a riser pipe with a fuimel-shaped end, it is easy to construct an experiment to prove the existence of osmotic pressure (Experiment 12.8). 

Experiment 12.8 Experimental demonstration of osmotic pressure The inside of the carrot is hollowed out in a cylindrical form and filled with a colored saturated calcium chloride solution. Then the riser pipe is attached. After a short time, one observes a continuous rise of the solution in the riser pipe. 

Cooling-water heat losses must be tallied, especially from bottom-fired zones, that is (a) skidrails pipes—insulated -I- uninsulated, (b) crossovers pipes—insulated -I- uninsulated, (c) riser pipes—insulated -f uninsulated. 

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