Pipes frictional pressure loss

APeU 90° standard ell in two-phase flow, psi APf pipe friction pressure loss, psi... 

Step 5. The pipe friction pressure loss APf, psi, is calculated in this step ... 

Skin friction loss. Skin friction loss is the loss from the shear forces on the impeller wall caused by turbulent friction. This loss is determined by considering the flow as an equivalent circular cross section with a hydraulic diameter. The loss is then computed based on well-known pipe flow pressure loss equations. 

The friction factor depends on the Reynolds number and duct wall relative roughness e/D, where e is the average height ol the roughness in rhe duct wall. The friction factor is shown in Fig. 9.46. For a Urge Reynolds number, the friction factor / is considered constant for rough pipe surfaces. The friction pressure loss is Ap c. ... 

Fp) = Friction pressure loss (total) at design basis, for a system, psi, for process equipment and piping, but excluding the control valve... 

For flow in pipes and ducts, where frictional pressure losses are important. Equation 2-53 can be modified into... 

The wellbore, drill string and drilling fluid data from the previous example are used. Casing depth is 4,000 ft. Assuming a drill pipe length of 5,000 ft and a drill collar length of 500 ft, find the friction pressure losses. 

The theory of pressure losses can be established by developing Bernoulli s theorem for the case of a pipe in which the work done in overcoming frictional losses is derived from the pressure available. For a fluid flowing in a pipe, the pressure loss will depend on various parameters. If... 

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). 

The terms represent, respectively, the effect of pressure gradient, acceleration, line friction, and potential energy (static head). The effect of fittings, bends, entrance effects, etc., is included in the term Ke correlated as a number of effective velocity heads. The inclination angle 0 is the angle to the horizontal from the elevation of the pipe connection to the vessel to the discharge point. The term bi is the two-phase multiplier that corrects the liquid-phase friction pressure loss to a two-phase pressure loss. Equation (23-39) is written in units of pressure/density. 

A convenient way to measure the density of a liquid is to pump it slowly through a vertieal pipe and measure the differentia] pressure between the top and the bottom of the pipe. This differential head is directly related to the density of the liquid in the pipe if frictional pressure losses are negligible. 

Step 5 Calculate pipe straight segment friction pressure loss APf. 

The friction pressure losses are calculated by summing up the pipe and fittings losses. 

Various studies have been conducted in predicting the two-phase frictional pressure losses in pipes. The Lockhart-Martinelli correlations [19] shown in Figure 3-7 are employed. The basis of the correlations is that the two-phase pressure drop is equal to the single-phase pressure drop of either phase multiplied by a factor that is derived from the singlephase pressure drops of the two-phases. The total pressure drop is based on the vapor-phase pressure drop. The pressure drop computation is based on the following assumptions ... 

Hgure A2.2 Plot of long-pipe approximation parameter, bo, against frictional pressure loss in veiocity heads, Kt. and pressure... 

A typical flow rate of 2 m3/min in the drill pipe (diameter = 0.1 m) gives a fluid velocity of 4.2 m/s, which causes fully turbulent flow in most drilling fluids. The calculation of the pressure drop down the length of the drill pipe is made somewhat complex by the flow being turbulent and the non-Newtonian rheology of the drilling fluid. These calculations are, however, important as about 30% of the total frictional pressure losses occur in the drill pipe. 

Annulus. From the drill pipe, the drilling fluid is jetted out of the bit nozzles and into the annulus. The jets are designed to remove drilled cuttings away from the drill bit. The pressure drop across the nozzles accounts for about 60% of the total frictional pressures losses during the circulation of the drilling fluid. About 90% of the pressure drop across the nozzles is due to the turbulence at the outlet, with only about 10% due to the flow through the nozzles. 

To extend the prediction of vs to flow regimes where Rec 0.1 it is necessary to use empirical correlations between Rec and a friction factor, similar to the approach used for calculating frictional pressure losses in turbulent pipe flow. The cutting friction factor/ is defined by... 

Figure 61. Measured frictional pressure losses of cuttings-seawater slurry during pipe flow as a function of flow rate. (Reproduced with permission from reference 168. Copyright 1993 Society of Petroleum Engineers.)...

For a given F, the height of liquid in the tank at steady state h is a constant, and a larger flow rate requires a higher liquid level. The liquid height provides just enough hydraulic pressure head at the inlet of the pipe to overcome the frictional pressure losses of the liquid flowing down the pipe. 

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