Base case design simulation

Throughout Chapters 1 and 3, the role of die process simulators is deemphasized. Rather, emphasis is placed on the steps in process synthesis and the development of the base-case design. Although from time to time these chapters refer to simulation results, a formal discussion of the role of process simulators during process creation is not attempted until Chapter 4 (and the accompanying multimedia CD-ROM). Chapter 3 introduces the steps in process synthesis without discussing many of the key heuristics used in making decisions. A more formal treatment is reserved for Chapter 5. 

Understand the many places that process simulators are useful during process synfliesB and when preparing the base-case design, as discussed in Sections 3.4 and 3.5. 

The mass- and energy-based indicators help to identify process alternatives for which sustainability metrics, environmental impact factors, as well as inherent safety indices can be estimated. The goal here is to optimize the process so that there is improvement in all these metrics with respect to the base case design. The application of the methodology requires a combination of tools ranging from databases to process simulation software (such as Aspen , Hypro , Sim Sci , etc.), to computational routines for various types of indicators and process synthesis/design tools. 

Hydrodealkylation of toluene is a process where toluene is converted into benzene by reaction with hydrogen, forming Diphenyl as a byproduct. This is a well known process, which has been studied in numerous publications. The reference design and flowsheet considered in this paper are taken from Seider et al. (1999), where further details can be found. The necessary steady state simulations have been performed with a commercial process simulator, from where the results have been transferred to a software developed for this work to calculate the indicator values. The steady state simulation results are also transferred to ICAS (ICAS Documentation, 2002) to determine the environmental impact factors, the sustainability metrics and the safety factors. Table 1 shows the most important indicator-values from the base case design. A detailed calculation results document can be obtained from the corresponding author. 

Closed loop simulations are given to demonstrate the improved controllability of the modifications resulting from the feedback optimal design methodology. The process is initially at the selected operating point from the base case design, i.e. MWav s = 25,000 and Few,., = 0.1673 mVh. 

Fig. 1. Simulation of polymerisation process for the base case design V = 0.1 m" and disturbance ATi = +3K...

The simulations indicate that the modifications have the ability to reject larger disturbances in the inlet temperature Tin than the base case design does. It is worth noticing that both the base case and the modifications can eventually be stabilised by the feedback control since there only exists output multiplicity in the MWav-Fc loop. But, a sudden change in the output could happen for a large disturbance during operation. 

Problem Stripper computer simulation for a base case did not match test data. Proper simulation was needed for revamp design checking. 

Abstract motif is a three-dimensional finite-element code developed to simulate groundwater flow, heat transfer and solute transport in deformable fractured porous media. The code has been subjected to an extensive verification and updating programme since the onset of its development. In this paper, additional verification and validation works with an emphasis on thermo-hydro-mechanical processes are presented. The verification results are based on cases designed to verify thermo-hydro-mechanical coupling terms, and isothermal and non-isothermal consolidations. A number of validation case studies have been conducted on the code. Example results are repotted in this paper. 

In order to be able to compare the CPB concept with other technologies, a basic design is made for a capture plant treating flue gases typically generated by a 600-MW coal-fired power plant, which is often used as a base case in literature sUidies. The bed dimensions and required process conditions are obtained by carrying out simulations by using the detailed model, which is described in the previous sections. The capital and operation costs are then estimated and the costs per ton of CO2 avoided are calculated. This section ends with a parameter study, in which the influence of several key parameters on the capture costs is evaluated. 

If the simulation fidelity is proven to be sufficient enough, it is ready to move to the next task, which is evaluation of the tower performance, because the purpose of reproducing the original design data is to understand the tower hydraulic and thermal performances of the base case and use the well defined base case to conduct what if analysis in order to identify improvements. 

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