Continuous Slugging

An important design detail is that the inlet line should be sloped at least 30" from the horizontal and the diameters of the vertical and sloped legs of the Y-seal are sized such that a 3 m slug of water is pressured back up the sloping inlet line, without spilling over into the header, in the event of flashback. Note that this requires an enlarged diameter section in the vertical leg of the Y-seal. The seal is maintained by a continuous flow of water at 1.26 dm /s and the water makeup is provided with steam injection, if required for winterizing or cold releases. 

The frequency of the batch treatment, or slug treatment, depends on the actual field response. The continuous method of treatment is relatively more expensive and can be four times as expensive as the batch treatment. 

Semi-annular flow. Liquid slugs were non-existent (Fig. 2.30e). A liquid film formed at the tube wall with a nearly continuous central vapor core, truncated periodically by churning liquid-vapor zones, which disappear gradually. 

The gas core with a thick liquid film is also shown in Fig. 5.14a, the second channel from the top. It is seen from this figure that a liquid film formed at the side walls of the channel with a continuous gas core in which a certain amount of liquid droplets exist. The flow with elongated cylindrical bubbles may be referred to as slug flow (Fig. 5.14b, the third channel from the top). 

Injecting a polymer solution as a protecting slug and then continuing with waterflooding [1823]... 

The core - flood apparatus is illustrated in Figure 1. The system consists of two positive displacement pumps with their respective metering controls which are connected through 1/8 inch stainless steel tubing to a cross joint and subsequently to the inlet end of a coreholder 35 cm. long and 4 cm. in diameter. Online filters of 7 im size were used to filter the polymer and brine solutions. A bypass line was used to inject a slug of surfactant solution. Two Validyne pressure transducers with appropriate capacity diaphragms are connected to the system. One of these measured differential pressure between the two pressure taps located about one centimeter from either end of the coreholder, and the other recorded the total pressure drop across the core and was directly connected to the inlet line. A two - channel linear strip chart recorder provided a continuous trace of the pressures. An automatic fraction collector was used to collect the effluent fluids. 

Finally, experimental procedures differing from that described in the preceding examples could also be employed for studying catalytic reactions by means of heat-flow calorimetry. In order to assess, at least qualitatively, but rapidly, the decay of the activity of a catalyst in the course of its action, the reaction mixture could be, for instance, either diluted in a carrier gas and fed continuously to the catalyst placed in the calorimeter, or injected as successive slugs in the stream of carrier gas. Calorimetric and kinetic data could therefore be recorded simultaneously, at least in favorable cases, by using flow or pulse reactors equipped with heat-flow calorimeters in place of the usual furnaces. 

When a pipeline is to be placed in service, the air in it shall be displaced. In order to avoid the creation of a combustible mixture, a slug of inert gas shall be introduced between the hydrogen and air. The hydrogen gas flow shall then be continued without interruption until all the air and inert gas have been removed from the facility. The vented gases shall be monitored and the vent closed before any substantial quantity of hydrogen gas is released to the atmosphere. Dead-ended legs of the pipeline system that cannot be swept by inert gas must be pressure purged. 

Flow-injection and continuous-flow systems are very similar. The major differences are outhned here. Continuous-flow systems are characterized by a relatively long start-up time prior to instrument stabilization, whereas the flow-injection approach requires little more time than that needed to stabilize the detector output. Tubing diameters on a flow-injection manifold are usually much smaller and the samples are injected into the flow line rather than aspirated. No wash cycle is employed in the flow-injection regime, since the sample is a discrete slug. Flow rates in continuous-flow manifolds are often larger than in the flow-injection regime. 

Second, when a liquid is flowing in a long tube, a liquid velocity profile will develop, and bubbles near the center of the tube will rise more rapidly than those near the wall. In slug flow, all slugs rise with nearly the maximum velocity, but in dispersed bubble flow, the variations in speed tend to cancel and give a component to the bubble velocity due to the average liquid velocity. As before, from continuity, this mean liquid velocity at any cross section must be (Qo + Qt)A, so that the bubble rise velocity is... 

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