Our objective here is to briefly popularize the concept of Pinch Analysis. Many existing sources are available to get more detailed information. A very simple example will be used to introduce the concepts.

1. The data

We start from a mass and energy balance data set to extract the information on the process streams that need some heating or cooling. This is expressed in terms of load (kW, GJ/hr, ...), initial and final (or target) temperature. See for example figure 1 for a very simple process of hot water production in a paper mill that consumes 4240 kW of steam. Figure 1 can represent an existing design which is itself based on many choices done by the engineer. To optimize the real problem and avoid any "topology trap" that would lead us on the same path than the original designer, we shall not start from this flowsheet, but rather from the basic generic flowsheet as shown in figure 2. 

From the energy balance, we extract the basic thermodynamic data for streams numbered 1 to 5 as shown in figure 3 (Please keep in mind this example aims at explaining the basic concepts. Here, there would be better ways to extract the data, this one is chosen to meet our purpose).

Computer process simulation is the best way to obtain the M&E balance data. It then becomes possible to simulate precisely the effect of any modification to the flowsheet, and there are often many of them found with Pinch Analysis in the course of the study. We can then update the original streams' data set with the computer simulation output. 

We may also need information in the following general areas, as defined by the mandate scope of work:

1. Energy costs and characteristics of utility equipments, including cogen;

2. Existing design of installed energy recovery equipment;

3. Heat transfer coefficients and pressure drop limitations;

4. Cost equations for different types of heat recovery equipment;

5. Constraints of any sort;

6. Management objectives;

7. Process / operation / production changes planned for the future.