Piping inlet

Inlet Piping Configurations. An incorrect piping configuration can create undesirable flow distortions that, especiaUy for double-suction pumps, means turbulence. Air pockets trapped in the pipe can cause uneven flow, vibrations, and pump damage. 

An acid egg, or blowcase, consists of an egg-shaped container which can be filled with a charge of liquid that is to be pumped. This container is fitted with an inlet pipe for the charge, an outlet pipe for the discharge, and a pipe for the admission of compressed air or gas, as illustrated in Fig. 10-58. Pressure of air or gas on the surface of the liquid forces it out of the discharge pipe. Such pumps can be hand-operated or arranged for semiautomatic or automatic operation. 

Excessive pressure drop in the separator and in the inlet piping... 

Generation of fine mist in the inlet piping, which escapes collection in the separator... 

Figure 7.17 Locally wasted region at an inlet pipe. See Fig. 7.18. Note the severe attack at the discharge end of the straight pipe.

Inlet pipe-circulation The coolant flows to the machine through inlet pipes from a source other than the surrounding medium and then freely discharges to the surrounding medium (as in the use of separately driven blowers) 1 Self-circulation Movement of the coolant is normally through a fan mounted on the rotor shaft, like a normal fan cooled motor (Figures I.l8(a)-(d) and 1.19(a) and (b)... 

Inlet and outlet pipe circulation The coolant Hows from a source other than the surrounding medium through the inlet pipes and is discharged remotely through the outlet pipes 3 ... 

Since a spool piece in the inlet piping is required for maintenance reasons, it is recommended that this be replaced by a flow measuring section containing the required instrumentation. 

On the expander side, the expander wheel is surrounded by the nozzle vanes. The nozzle vanes, in turn, reeeive gas from a toroidal spaee that is eonneeted to tlie expander inlet piping. Any non-uniformity in the torus spaee and/or in the nozzle vane design may result in a non-uniform pressure distribution around the expander wheel. Non-uniform gas pressure around the expander wheel will result in a non-uniform load and, henee, produee a gas dynamie radial load on the bearing. In the expander ease, however, the nozzle throat flow resistanee is mueh larger than the easing peripheral pressure nonuniformity. The latter aets as a buffer making the expander wheel eireumferential pressure variations smaller than those of the eompressor side. This smaller pressure variation produees mueh less radial load when eompared to that of the eompressor side. 

Used for small duties, clean process, and only infrequent cleaning required. Vaporization is usually less than 30%, but less than 15% if the fractionator pressure is below 50psig. The viscosity of the reboiler feed should be less than 0.5 cp. Put a butterfly valve in the reboiler inlet piping. This type is used in nearly 100% of chemical plant thermosyphon applications (70% of petrochemical). 

Figure 5-28. Chart for minimum straight inlet piping. Use this chart and the given factors in conjunction with Figure 5-29. Courtesy of Elliott Company...

Inlet pipes to vessels should be directed toward the center. Also, the inlet pipe should protrude into the tank and as close as possible to the normal... 

When the predetermined system blowdown pressure is reached, the pilot valve closes, full system pressure is restored to the dome above the piston, and the piston is quickly moved to the closed position. The pilot valve pressure sensing point may be located in the main valve inlet neck, or on the shell of the vessel being protected. The valve is less affected by inlet piping pressure drop in the latter case, as described below. 

Process systems handling polymers and resins (e.g., butyl rubber or ethylene-propylene diene monomer rubbers) are often subject to plugging at dead-end locations such as PR valve inlets. In extreme cases, complete blockage of inlet piping and valve nozzle can result. This problem can be eliminated by the application of a flush-seated PR valve, in which dead-end areas are eliminated by placing the valve disc flush with the vessel wall, in the flow pattern of the contents. 

Chattering caused by undersized inlet piping may sometimes be eliminated on pilot operated PR valves if the pilot valve pressure tapping is taken directly from the vessel being protected. However, it is recommended that the above inlet pressure drop limitations still be applied, to avoid the capacity reduction that would result from excessive inlet losses and to ensure freedom from chatter. 

Heat tracing of PR valve inlet piping should be provided where plugging by icing, deposition of wax or congealing of viscous liquids may occur at ambient temperatures. 

Flare systems are subject to potential flashback and internal explosion since flammable vapor/air mixtures may be formed in the stack or inlet piping by the entry of air, and the pilot constitutes a continuous ignition source. Flares are therefore always provided with flashback protection, which prevents a flame front from travelling back to the upstream piping and equipment. Design details are described later. 

Inlet Piping and Flashback Protection - In non-freezing climates, for services... 

The Seal Drum - A typical flare seal drum for an elevated flare stack is illustrated in Figure 7. A baffle maintains the normal water level, and the vapor inlet is submerged 75 mm to 100 mm. Drum dimensions are designed such that a 3 m slug of water is pressured back into the vertical inlet piping in the event of... 

An example of a distributor design is shown in Figure 10. Hole density is low at the top of the pipe and is increased lower on the pipe. The maximum open area density of about 10% assures reasonable bubble formation in this design. The average veloeity out of the top row of holes starts at about 40 m/s and increases as the pressure rises and total flow increases. Total areas of holes plus bottom slot should be equal to at least two times the cross sectional area of the inlet pipe. 

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