Missing flow calculation

Data correlation (performance test), 491-497 material balance, 492 energy balance, 492-494 missing flow calculation, 494 hydraulic losses, 494-495 pumps, 495-496 Debutanizer, 261, 377-381 Decoking crew (coking cycle), 50, 56-57... 

Step 2 Calculate Missing Flows The balancing starts from the LP header and goes upward to MP and HP headers until the boiler. The initiator of the balancing procedure is the assumption of LP to deaerator as 25 klb/h. 

With the DA steam of 19 klb/h newly calculated, the same procedure as above for calculating the missing flows is repeated to give the closed steam balance as shown in Figure 16.6. 

Component balance Fractionation efficiency Overall unit energy balance Furnace efficiency Heat exchanger U s Calculate missing flows Hydraulic losses Pump efficiency Identify capital projects Normalizing data... 

During this preparation stage, analysts will frequently find that there is insufficient quantity or quality of measurements to close the material balance. Analysts should make eveiy effort to measure aU stream flows and compositions for the actual test. They should not rely upon closing material balances by back-calculating missing streams. Tne material balance closure will provide a check on the vahdity of the measurements. This preparatoiy material balance will help to identify additional measurements and schedule the installation of the additional instruments. 

In space, NASA calculates fluid flow by applying equations such as Eq. (6.12). This equation is missing the constant g since Earth s gravity force is missing in space [9]. 

A comparison of the Ml nonlinear relationship (2-155) with the linear form (2-156) is shown in Fig. 2 22. Although (2-156) is often used in fluid dynamic calculations because of the simplicity that derives from the fact that it is linear, it can be seen from Fig. 2 22 that it requires T/ Too <strong reduction in the interfacial tension as F Too often has important consequences in flow systems, because the convection of surfactant on the interface often produces local regions of high concentration, but these will all be missed if the linear form (2-156) is used. Further discussion of surfactant adsorption at the fluid interface can be found either in classic textbooks48 or the research literature (e g., Pawar and Stebe)49... 

In this last equation, the first term on the right-hand side is the entropy change of stream 1 from its initial temperature to the final temperature of stream 3, and the second term is the entropy change of the cold stream from its initial temperature to the exit temperature in stream 3. The entropy terms can be calculated since all temperatures are known. What is still missing is the mass flow rate of stream 2. This is obtained from the energy balance ... 

FIGURE 1U2. (a) Purity (% normal paraffins) and (b) flow rate of the hydrocarbon stream leaving the sieve bed during steady-stale cyclic operation of the Ensorb linear paraffins unit at Baytown refinery (arbitrary units). The lines are theoretical curves calculated from a detailed numerical simulation of the system, points arc plant data. (Courtesy of Aromatics Technology, Exxon Chemicals Corporation. Plant data were provided by Miss Ann Lucas and the numerical simulation was carried out by Dr. H. Yoshida.)... 

Hence, we can measure the fuel flow, correct both the fuel flow and power to ISO conditions, and then eompare the results to the expected fiiel consumption from Figure 4. The deviation in this case is the degradation parameter we ean monitor over time. The problem most will face for this rule is a reliable measurement of the fuel flow rate. Many installations either have missing or inaccurate fuel meters. This can be substituted for by ealeulating the fuel flow. For machines with Mark V or VI controllers, we can use the choking condition on the gas control valve (GCV) to do this. A robust approach then would be to compare the calculated to the measured value (if available) and use it accordingly in the fuel consumption rule. 

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