Calculating outlet piping

Calculate the pressure drop in the outlet piping (two-phase). 

In this example, the value of 1/a is small compared with 4/2L,/d, and could be ignored. When this is not the case it will be necessary to know whether the flow in the outlet pipe is laminar or turbulent, so that the appropriate value of a can be used. The following calculation shows how this can be done. 

The synthesis is carried out in a cascade of three consequtive reactors 9 of the same type. The parent substances are continuously sent through collector 8 into first reactor 9 from there, the products of the reaction flow into the second and the third reactors. The given level in the first two reactors is supported by pouring the products through the piping for the third, a pressure regulator is used with a gate located on the outlet pipe. Strict observance of the level is necessary to keep the calculated synthesis time. 

Calculate the relief area required based on the duty, inlet and outlet piping, and downstream equipment. This is also a rather involved calculational procedure. 

Ail of the terms of the Bernoulli equation, Equation 7.7-3, are known except tiP, the variable to be determined, and which must be calculated from the known liquid flow rate and the diameters of the inlet and outlet pipes. 

The size of outlet piping required for a safety disc is not necessarily the same as the disc receptacle size. Discs frequently are sized on the basis of pressure requirements rather than capacity requirements. In such instances it is possible for the outlet piping to be smaller than the pipe size of the disc receptacle. If an arrangement of this type is desirable, the pipe diameter must be calculated on the basis of the relief capacity requirements and the maximum allowable upstream pressure. The inlet piping, however, must have an area which is at least equal to that of the receptacle in order to comply with the ASME code. 

One can observe substantial differences between the previous 2D axisymmetric and present 3D simulations, both in calculated particle trajectories and in the behavior of specific parameters. Thus, 2D axisymmetric simulations expect downward particles motion in the region of the chamber central core and particle upward movement in the periphery of the chamber conical part. In contrast, the present 3D calculations predict asynunetric particle flow in the spray chamber particle descending motion in the central core and subsequent upward particle transport with recirculation that occurs mainly in the chamber half opposed to the air outlet pipe. Moreover, the results show that according to the previous 2D axisynunet-ric calculations, the large particles hit the walls during their... 

In the simulation of Gas-liquid two-phase separation, the gas outlet pipe length is set to 745 mm, droplet diameter is set to 10 p.m, the gas volume concentration distribution of the shaft section of the separator is get by simulation and calculation of the process of the separation by CFD software, and the contours volume fraction of gas is shown in Figure 4. 

For preliminary calculation, PI can be assumed to be equipment relieving pressure at 10% ovetpressure for non-fire case or 21% overpressure at fire case. After PRD inlet and outlet piping are designed, an updated PI and P2 based on hydraulic calculation should be used to recheck the vapor relief is sonic or not... 

For backpressure correction factor (Kb), estimate the backptessure at PRV outlet Then, find Kb from manufacturer s catalog. Kb depends on the type of PRV (conventional or balanced-bellows) used. Forpiloted-operated PRV and rupture disk, Kb equals to LO. Kb needs to be rechecked once the PRV outlet piping is designed, and its backpressure for rated flow case is calculated by a hydraulic analysis,... 

Another criterion for PRV outlet piping size is that max. vapor line velocity should be less fiian 50-75% of sonic velocity, depending on the project requirement. Sonic or critical velocity of vapor (Vc, in ft/sec) is calculated by following equation ... 

If in-house, personnel are required to provide a flare system piping layout, many good literature articles are available. Reference 2 has simplified the procedure by allowing the calculations to begin with the outlet (atmospheric pressure) and work back towards the source thus overcoming tedious trial and eiTor required by methods that require beginning at the source. 

When the relieving scenarios are defined, assume line sizes, and calculate pressure drop from the vent tip back to each relief valve to assure that the back-pressure is less than or equal to allowable for each scenario. The velocities in the relief piping should be limited to 500 ft/sec, on the high pressure system and 200 ft/sec on the low pressure system. Avoid sonic flow in the relief header because small calculation errors can lead to large pressure drop errors. Velocity at the vent or flare outlet should be between 500 ft/sec and MACH 1 to ensure good dispersion. Sonic velocity is acceptable at the vent tip and may be chosen to impose back-pressure on (he vent scrubber. 

Note when used for pump system balance, this Zhf must be used as a negative number ( — 0.1863) because it is a pressure loss associated with the fluid flowing. For pipe line sizing, the pressure head on the tank of 5 psig and any elevation difference between tank outlet nozzle and pump suction centerline do not enter into the calculations. 

Note that determining the velocity at the inlet conditions to a pipe may create significant error when results are concerned with the outlet conditions, particularly if the pressure drop is high. Even the average of inlet and outlet conditions is not sufficiently accurate for some systems therefore conditions influenced by pressure drop can produce more accurate results w hen calculations are prepared for successive sections of the pipe system (long or high pressure). 

In general, the sonic or critical velocity is attained for an outlet or downstream pressure equal to or less than one half the upstream or inlet absolute pressure condition of a system. The discharge through an orifice or nozzle is usually a limiting condition for the flow through the end of a pipe. The usual pressure drop equations do not hold at the sonic velocity, as in an orifice. Conditions or systems exhausting to atmosphere (or vacuum) from medium to high pressures should be examined for critical flow, otherwise the calculated pressure drop may be in error. 

Reboiler piping at the liquid inlet and at the vapor outlet can be summarized for convenience in pressure drop calculations into the suggested equivalent feet of Table 10-32. The inlet assumes piping to conveniently pipe the reboiler to a distillation column using welded fittings and a full open gate... 

The consistency of the data can be checked by comparing values calculated using equation 5.18 with measured values for samples collected at the outlet of the pipe. 

Calculate the power required to pump oil of specific gravity 0.85 and viscosity 3 mN s/m2 at 4000 cm3/s through a 50 mm pipeline 100 m long, the outlet of which is 15 m higher than the inlet. The efficiency of the pump is 50% . What effect does the nature of the surface of the pipe have on the resistance ... 

A boat is tied to a dock by a line from the stern of the boat to the dock. A pump inside the boat takes water in through the bow and discharges it out the stem at the rate of 3 ft3/s through a pipe running through the hull. The pipe inside area is 0.25 ft2 at the bow and 0.15 ft2 at the stern. Calculate the tension on the line, assuming inlet and outlet pressures are equal. 

In any real situation, reactants only flow through the reactor because there is a difference in pressure between the inlet and the outlet. Methods for calculating the pressure drop in pipes and packed beds have been outlined in Chap. 1. Often, the pressure drop is negligible compared with the total pressure and it is usual to assume that a tubular reactor with plug flow operates at constant pressure. 

Here Ap = (p., - P2) is the differential between the pressures at the inlet and outlet ends of the piping element. The proportionality factor C is designated as the conductance value or simply conductance . It is affected by the geometry of the piping element and can even be calculated for some simpler configurations (see Section 1.5). 

A condenser consists of 30 rows of parallel pipes of outer diameter 230 mm and thickness 1.3 mm with 40 pipes, each 2 m long in each row. Water, at an inlet temperature of 283 K, flows through the pipes at 1 m/s and steam at 372 K condenses on the outside of the pipes. There is a layer of scale 0.25 mm thick of thermal conductivity 2.1 W/m K on the inside of the pipes. Taking the coefficients of heat transfer on the water side as 4.0 and on the steam side as 8.5 kW/m2 K, calculate the water outlet temperature and the total mass flow of steam condensed. The latent heat of steam at 372 K is 2250 kJ/kg. The density of water is 1000 kg/m3. 

Calculate the outlet air temperature for the double-pipe heat exchanger under the conditions of Example 7.33 if the tube has 24 steel fins 0.5 in (0.013 m) high and 0.03125 in (0.794 mm) thick. 

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