Loss calculation

Example 8 Compressible Flow with Friction Losses Calculate the discharge rate of air to the atmosphere from a reservoir at 10 Pa gauge and 20 G through 10 m of straight 2-in Schedule 40 steel pipe (inside diameter = 0.0525 m), and 3 standard radius, flanged 90 elhows. Assume 0.5 velocity heads lost for the elhows. 

To ascertain profit or loss (calculated as income minus expenditure for a given accounting period), income and expenditure must be matched. For example, any rent paid in advance beyond the current accounting period should not be included in the profit or loss calculation. Similarly, goods sold but not yet paid for in a given accounting period should not be included in the revenue total for that period. 

For a high-temperature system, a separate subheader may be run up to the point where the temperature drops down to the allowable limit of a less expensive material. It may then be connected to the main flare header (either low pressure or high pressure).To properly evaluate this a heat loss calculation is needed. As a rule of thumb a heat loss of 10 BTU/hr/ft may be assumed for a quick estimate for bare pipe. Consideration should also be given to the need for expansion joints. Main flare headers may be as large as 36 to 42 inches in diameter for a large-capacity plant. Expansion joints of such magnitudes may be so expensive as to call for a separate small header for the hot flare system. 

Lapple s method is useful when the upstream pressure of a header is known and the downstream pressure has to be calculated. However, it is often required to develop the pressure profile of the flare headers as a function of the distance from the stack. For this reason, it is more convenient to calculate the pressure drop backward, starting from the flare stack exit where the pressure is atmospheric. Figure 20 provides another plot which enables the pressure loss calculation when the downstream pressure is known. 

Ducts and fittings Diameter, length, specific data for pressure-loss calculation... 

The important factor in the pressure loss calculations will be c, the velocity of the conveyed material, and therefore it is important to know this term. It is clear that with the same gas velocity v, the velocity of the conveyed material will be different at various pipe inclination angles S. In this section we... 

Height allowance A percentage added to heat loss calculations to compensate for the vertical temperature gradient. 

The head losses calculated using K coefficients by these figures can be added directly to the total friction head loss for the straight pipe portions of a system. When equivalent lengths are determined, they must be added to the straight pipe before determining the total head loss, as shown in the example calculations for a water system. 

Note For quick estimates not as accurate as friction loss calculations... 

A fan conveying standard air at 3,000 acfm is to be selected for a system. (Using the duct loss calculations in Chapter 2, Flow of Fluids V. 1, 3 Ed., of this series). Establish at assumed 4,400 ft/min (Table 12-15). 

Rheological Classification of Drilling Fluids 829. Flow Regimes 830. Principle of Additive Pressures 834. Friction Pressure Loss Calculations 836. Pressure Loss Through Bit Nozzles 839. 

Underreamer Hydraulics. Pressure losses across the underreamer nozzles (orifice) are shown in Figures 4-178 and 4-179 [58]. The shaded area represents the recommended pressure drop required for cutters to fully open. These pressure drop graphs can be used for pressure losses calculations (given pump output and nozzles) or for orifice (nozzle) selection (given pump output and pressure loss required). 

It also contains heat loss calculation methods. This Standard should be the basis for any specification drawn up by a company that does not have its own in-house insulation standards manual. 

Neglecting radiation losses, calculate the mass of dry air passing through the dryer and the humidity of the air leaving the dryer. 

Using the yield figures given, and neglecting any other losses, calculate the flow of ethylene to each reactor and the flow of DCE to the pyrolysis reactor, for a production rate of 12,500 kg/h vinyl chloride (VC). 

Figure 3.47 Experimental and calculated values of the relative frictional pressure losses --, calculation from Kirillov et al. (1978) ---, calculation from CISE (1963) -------, calculation from Gill et al. (1963) ----, calculation from Schraub (1968). (From Kirillov et al., 1978. Copyright ... 

Hydrolysis rate measurements. Hydrolysis rates were examined by mixing polymer solutions with hydrochloric acid, in apparatus previously described (5). Solutions of polymer and acid are mixed rapidly, and the torque on a rotating PTFE coated fork, attached to a Brookfield LVTD viscometer, recorded as a function of time. Decreases in viscosity were approximated to first-order, and half-lives for viscosity loss calculated. 

These data were obtained by mixing the SOx additive with a low alumina cracking catalyst and steaming at 1400°F in 100% steam in a fixed bed for 5 hours. The concentration of additive was adjusted so that the initial activity was approximately the same for all materials. (The amounts were the same as those used for the regenerability test.) The SO2 removal ability was then measured before and after steaming and the % loss calculated. The average deviation was 7%. 

Moisture.—5-10 grams of the finely divided bather are dried at loo-105 to constant weight and the percentage loss calculated. 

The pressure loss through the bends and check valves can be included in the line pressure-loss calculations as an equivalent length of pipe . The equivalent-length recommendations are taken from Ref. P1 (p.164). All the bends are assumed to be 90 elbows of standard radius, and the isolation valves as plug-type valves. 

Figure 68. Dielectric loss calculated for the composite model (solid lines) experimental curves [17, 51, 54] (dashed lines) contribution to loss due to dipoles performing restricted rotation in the parabolic potential (dot-dashed lines).

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