Pipes liquids, flow through

Figure 7-23. Parameters for pressure drop in liquid/gas flow through horizontal pipes. (Source Lockheed and Martinelli, Chem. Engr. Prog., 45, 39, 1949.)...

The net head or pressure measured in ft. or m that causes a liquid to flow through the suction side of a pump, enter the pump chamber, and reach the impeller. When the source of liquid is above the pump, NPSH equals the barometric pressure plus the static head, less the entrance head, frictional losses in the suction piping and vapor pressure of the liquid. When the source of liquid is below the pump, NPSH equals the barometric pressure less the static head, entrance head, frictional losses in the suction piping and vapor pressure of the liquid. NPSH is specific for each pump design and application and must be supplied by the manufacturer. 

Nalone, W.T., Holtmyer, M.D., Tinsley, J.M., and Chattopadhyay, J. "Additive for Reducing Friction Pressure Loss of Liquid Hydrocarbons Flowing Through Pipes," German Patent 2,056,700(1971), Chemical Abstracts 75(12) 78860y(1971). 

Liquid Viscosity — The value (in centipoise) is a measure of the ability of a liquid to flow through a pipe or a hole higher values indicate that the liquid flows less readily under a fixed pressure head. For example, heavy oils have higher viscosities (i.e., are more viscous) than gasoline. Liquid viscosities decrease rapidly with an increase in temperature. A basic law of fluid mechanics states that the force per unit area needed to shear a fluid is proportional to the velocity gradient. The constant of proportionality is the viscosity. 

Several distributor types are available trough, orifice-rise, and perforated pipe. Examples of these types are shown in Fig. 14-64. The trough distributor provides good distribution under widely varying flow rates of gas and liquid. The liquid may flow through simple V-notch weirs, or it may flow throu tubes that extend from the troughs to near the upper level of the packing. Some deposition of solids can be accommodated. 

FIGURE 10.4.5. Flow patterns in cocurrent liquid-gas flow through horizontal pipes. Cg = gas mass velocity (Ib s ft ) G = liquid mass velocity (lb ft ) m = liquid viscosity (centipoise) pg = gas density (lbft ) /5 = liquid density (lb(cuft) ) liquid surface tension (dynes cm ) X = ((/Og/0.075)(pi/62.3)) / = (73/cr)(jii(623/(from Ref. 2). (Reproduced with permission of The McGraw-Hill Companies.)... 

A liquid is flowing through a horizontal straight commercial steel pipe at 4.57 m/s. The pipe used is commercial steel, schedule 40, 2-in. nominal diameter. The viscosity of the liquid is 4.46 cp and the density 801 kg/m. Calculate the mechanical-energy friction loss Fy in J/kg for a 36.6-m section of pipe. 

A liquid is flowing through a 6-mm-diameter orifice with flange taps in a 50 NB sch. 40 pipe. The flow parameters are presented as follows. Estimate the maximum nonrecoverable pressure drop. 

Fig. 3. Comtrack 921 pipe prover. Liquid flow through the Comtrak s closed loop is created by the movement of a sealed piston. Flow meters being tested are installed in the loop upstream from the piston. As the piston advances, the caUbration fluid travels through the meters and returns to the back side of...

In biphase systems velocity of the steam is often 10 times the velocity of the liquid. If condensate waves rise and fill a pipe, a seal is formed with the pressure of the steam behind it (Fig. 2). Since the steam cannot flow through the condensate seal, pressure drops on the downstream side. The condensate seal now becomes a piston accelerated downstream by this pressure differential. As it is driven downstream it picks up more liquid, which adds to the existing mass of the slug, and the velocity increases. 

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