Pipe reduction

Analysis has also been carried out for the DEGR at the grid plate end of pipe. Reduction in the resistance of flow passage from grid plate to ruptured end causes leakage flow through that path to increase. However, increase in flow resistance in the path from pump header to ruptured end causes flow in that path to decrease and flow through the other unruptured pipe to increase. As a consequence of these two effects core flow falls to a minimum value (before scram) of 31%, which is better than the rupture at the header end. 

Further reductions in reservoir pressure move the shock front downstream until it reaches the outlet of the no22le E. If the reservoir pressure is reduced further, the shock front is displaced to the end of the tube, and is replaced by an obflque shock, F, no pressure change, G, or an expansion fan, H, at the tube exit. Flow is now thermodynamically reversible all the way to the tube exit and is supersonic in the tube. In practice, frictional losses limit the length of the tube in which supersonic flow can be obtained to no more than 100 pipe diameters. 

Different resins have been developed for use in different reduction—ratio appHcation ranges (111,112). The powders suitable for high reduction—ratio appHcations, such as wire coatings, are not necessarily suitable for the medium reduction—ratio appHcations, such as tubings, or the low reduction—ratio appHcations, such as thread-sealant tapes or pipe liners. AppHcations and processing techniques are being used, which utilize the unique combination of properties offered by PTFE in fine powder form (113—115). 

If the drill string becomes differentially stuck, mechanical methods or spotting fluids can be appHed, or the hydrostatic pressure can be reduced (147). In general, penetration of water- or oil-based spotting fluids into the interface between the filter cake and the pipe accompanied by dehydration and cracking results in reduction of differential pressure across the drill string (147,148). Spotting fluids are usually positioned in the open hole to completely cover the problem area. 

All lation. The combination of olefins with paraffins to form higher isoparaffins is termed alkylation (qv). Alkylate is a desirable blendstock because it has a relatively high octane number and serves to dilute the total aromatics content. Reduction of the olefins ia gasoline blendstocks by alkylation also reduces tail pipe emissions. In refinery practice, butylenes are routinely alkylated by reaction with isobutane to produce isobutane—octane (26). In some plants, propylene and/or pentylenes (amylenes) are also alkylated (27). 

Reduced Emissions and Waste Minimization. Reducing harmful emissions and minimizing wastes within a process by inclusion of additional reaction and separation steps and catalyst modification may be substantially better than end-of-pipe cleanup or even simply improving maintenance, housekeeping, and process control practices. SO2 and NO reduction to their elemental products in fluid catalytic cracking units exemplifies the use of such a strategy (11). 

Tees Tees may be cast, forged, or hot- or cold-formed from short pieces of pipe. Though it is impossible to have the same flow simultaneously through all three end connections, it is not economical to produce or stock the great variety of tees which accurate sizing of end connections requires. It is customary to stock only tees with the two end (run) connections of the same size and the branch connection either of the same size as the run connections or one, two, or three sizes smaller. Adjacent reducers or reducing elbow fittings are used for other size reductions. Branch connections (see subsection Joints ) are often more economical than tees, particularly when the ratio of branch to run is small. 

The transfer of supersaturated liquor from the vaporizer (point B, Fig. 18-69) often causes salt buildup in the piping and reduction of the operating cycle in equipment of this type. The rate of buildup can be reduced by circulating a thin suspension of solids through the vaporizing chamber however, the presence of such small seed ciystals tends to rob the supersaturation developed in the vaporizer, thereby lowering the efficiency of the recirculation system. 

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