Steam system optimization model

The only way to reconcile the true cost implications of a reduction in steam demand created by an energy reduction project is to use the optimization techniques described in the previous section. An optimization model of the existing utility system must first be set up. Starting with the steam load on the main with the most expensive steam (generally the highest pressure), this is gradually reduced and the utility system reoptimized at each setting of the steam load. The steam load can only be reduced to the point where the flowrate constraints are not violated. 

Complex steam systems usually feature many important degrees of freedom to be optimized. To establish the steam costs for retrofit of site processes requires an optimization model to be developed. This allows the steam loads for process heating to be gradually decreased and the steam system reoptimized at each setting. The result in cost... 

Although the details of establishing steam balances are discussed in Chapter 16 while steam equipment modeling equations are given in Chapter 15, the intention here is to combine all the related equations to develop a complete simulation and optimization model for the steam system. For specific applications, users can revise the model by providing specific configuration and conditions for the steam system. 

In 2000 two major petrochemical companies installed process NMR systems on the feed streams to steam crackers in their production complexes where they provided feed forward stream characterization to the Spyro reactor models used to optimize the production processes. The analysis was comprised of PLS prediction of n-paraffins, /xo-paraffins, naphthenes, and aromatics calibrated to GC analysis (PINA) with speciation of C4-C10 for each of the hydrocarbon groups. Figure 10.22 shows typical NMR spectral variability for naphtha streams. Table 10.2 shows the PLS calibration performance obtained with cross validation for... 

For all these phenomena, high-fidelity predictive CFD methods are sought to be applied in connection with experiments as predictive tools. This is true for flow assurance modeling, in particular as to subsea oil production and transport, and in EOR systems, including using steam or Carbone Dioxide injection in wellbores. At the downstream level, say when use is made of the treated gas for energy production, various technical issues still pertain, as in the gas turbine combustion sector, where CFD is also required to optimize fuel injection, atomization and mixing. 

There is also a heat loss term associated with the high-pressure steam drum. This term is typically used to imderstand the whether significant errors exist in boiler feed water flows, steam flows and temperatures, furnace convection section measurements, and fuel flow and composition measurements. During the optimization system commissioning sensitivity of this term to the aforementioned measurements helps those commissioning the system eliminate the worst measurements, and establish the validity of the models. 

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