Process integration composite curve

Although the composite curves can be used to set energy targets, they are not a suitable tool for the selection of utilities. The grand composite curve is a more appropriate tool for understanding the interface between the process and the utility system. It is also, as is shown in later chapters, a useful tool for study of the interaction between heat-integrated reactors and separators and the rest of the process. 

Let us now consider a few examples for the use of this simple representation. A grand composite curve is shown in Fig. 14.2. The distillation column reboiler and condenser duties are shown separately and are matched against it. Neither of the distillation columns in Fig. 14.2 fits. The column in Fig. 14.2a is clearly across the pinch. The distillation column in Fig. 14.26 does not fit, despite the fact that both reboiler and condenser temperatures are above the pinch. Strictly speaking, it is not appropriately placed, and yet some energy can be saved. By contrast, the distillation shown in Fig. 14.3a fits. The reboiler duty can be supplied by the hot utility. The condenser duty must be integrated with the rest of the process. Another example is shown in Fig. 14.36. This distillation also fits. The reboiler duty must be supplied by integration with the process. Part of the condenser duty must be integrated, but the remainder of the condenser duty can be rejected to the cold utility. 

Establish the heat integration potential of simple columns. Introduce heat recovery between reboilers, intermediate reboilers, condensers, intermediate condensers, and other process streams. Shift the distillation column pressures to allow integration, where possible, using the grand composite curve to assess the heat integration potential. 

Figure 16.38 shows a heat pump appropriately integrated against a process. Figure 16.38a shows the overall balance. Figure 16.38b illustrates how the grand composite curve can be used to size the heat pump. How the heat pump performs determines its coefficient of performance. The coefficient of performance for a heat pump can generally be defined as the useful energy delivered to the process divided by the power expended to produce this useful energy. From Figure 16.38a ...

The appropriate placement of distillation columns when heat integrated is not across the heat recovery pinch. The grand composite curve can be used as a quantitative tool to assess integration opportunities. The scope for integrating conventional distillation columns into an overall process is often limited. Practical constraints often prevent integration of columns with the rest of the process. If the... 

Refrigeration cycles offer many opportunities for heat integration with the process. These can be explored using the grand composite curve. 

The most fundamental concepts in Pinch analysis are Composite and Grand Composite Curves. Composite Curves (Fig. 10.1-left) visualises the flow of heat between the hot and cold process streams selected for heat integration. A composite curve is obtained by plotting the cumulative enthalpy of streams, cold or hot, against temperature. The relative position of the composite curves depends on the minimum temperature difference between cold and hot streams. This sets also the Pinch position as the place where the heat transfer between the hot and cold streams is the most constrained. 

The counter-current heat flow of the streams selected for integration may be represented by means of Composite Curves (CC). Another diagram. Grand Composite Curve (GCC) allows the visualisation of the excess heat between hot and cold streams, against temperature intervals. This feature helps the selection and placement of utilities, as well as the identification of the potential process/process matches. 

The process integration principles outlined above provide the guidelines for process changes in general. It is clear that both composite curve and grand composite curve are very powerful tools that allow us to optimize process integration for the entire... 

PROCESS INTEGRATION OPPORTUNITY ASSESSMENT Composite curves... 

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