Heat integration case study

Task Revisit the case study shown in Figs. 10.6 and 10.7 and apply the presented formulation over a 20 h time horizon. Assess the benefits of heat integration in this particular case, i.e. compare the energy requirements for the heat integrated case to the standalone case. 

Distillation sequencing. Unless there are constraints severely restricting heat integration, sequencing of simple distillation columns can be carried out in two steps (1) identify the best few nonintegr-ated sequences, and (2) study the heat integration. In most cases, there is no need to solve the problems simultaneously. ... 

The objective of this case study is to use heat integration via the pinch diagram to reduce this operating cost. A value of Ar" " = 10 K. 

The case study was solved using the uneven discretization of time formulation presented in this chapter. The mathematical model for the scenario without heat integration (standalone mode) involved 88 binary variables and gave an objective value of 1060 rcu. This value corresponds to the production of 14 t of product and external utility consumption of 12 energy units of steam and 20 energy units... 

Fig. 10.8 Gantt for the case study - heat integration (Majozi, 2006)...

A uneven discretization of time mathematical formulation for direct heat integration of multipurpose batch plants has been presented. The formulation results in smaller problems compared to the discrete-time formulation, which renders it applicable to large-scale problems. Application of the formulation to an industrial case study showed an 18.5% improvement in objective function for the heat-integrated scenario relative to the standalone scenario. 

Whilst direct heat integration, i.e. without any use of heat store, resulted in 25% improvement in terms of external cold utility requirements, use of heat storage showed more than 75% improvement. In this particular case study, both direct and... 

A mathematical approach for optimization of energy use in heat integrated multipurpose batch plants has been presented and tested in a case study. The results have shown that heat integration with heat storage considerations can result in energy savings of more than 75%, compared to standalone operation that relies solely on... 

In order to compare the economics as well as the overall C02 emissions from each schematic studied in this joint venture, a reference case was analyzed. The reference case included only the process steps associated with coal gasification, shift, and hydrogen purification, but none of the steps associated with C02 sequestration or coalbed methane recovery. Three other process schemes were examined in this study and compared to the reference case. Figure 1 depicts simplified process flow diagrams for the reference case and the other three schemes (note the overall heat integration for each scheme is not shown). The top portion of the figure shows the process steps that are the same for each scheme up to hydrogen purification, while the operations inside the dashed boxes represent the steps that differ between the four cases. 

The thermal entrance region in a hydrodynamically fully developed flow in a rectangular duct may be studied by the use of the integral method. In this section, the uniform wall temperature and the uniform wall heat flux cases are discussed. The physical model is based on the following assumptions ... 

Based on the results of the process development work the design of a commercial-scale HTU process unit is now under way. Heat integration and energy economy are of prime importance to keep the processing cost low. A useful criterion for the energy economy is the thermal efficiency. This paper discusses a case study of such a process design. 

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