Maximum energy recovery

In practice, the integer number of shells is evaluated from Eq. (7.18) for each side of the pinch. This maintains consistency between achieving maximum energy recovery and the corresponding minimum number of units target Nu- ixs- In summary, the number of shells target can be calculated from the basic stream data and an assumed value of Xp (or equivalently,... 

Example 16.1 The process stream data for a heat recovery network problem are given in Table 16.1. A problem table analysis on these data reveals that the minimum hot utility requirement for the process is 15 MW and the minimum cold utility requirement is 26 MW for a minimum allowable temperature diflFerence of 20°C. The analysis also reveals that the pinch is located at a temperature of 120°C for hot streams and 100°C for cold streams. Design a heat exchanger network for maximum energy recovery in the minimum number of units. 

The pinch design method developed earlier followed several rules and guidelines to allow design for minimum utility (or maximum energy recovery) in the minimum number of units. Occasionally, it appears not to be possible to create the appropriate matches because one or other of the design criteria cannot be satisfied. 

Figure 16.16 Maximum energy recovery design for Example 16.2.

Figure 16.23a shows the complete design, achieving maximum energy recovery in one more unit than the target minimum due to the inability to tick off streams below the pinch. 

MER maximum energy recovery for given set of process streams... 

MER j, maximum energy recovery with network approach of AT... 

Potential maximum energy recovery versus practical achievable energy recovery of various plastics waste... 

The proposed network for maximum energy recovery is shown in Figure 3.27. 

Start with the design for maximum heat recovery. The number of exchangers needed will be equal to or less than the number for maximum energy recovery. 

Determine the pinch temperatures and the minimum utility requirements for the streams set out in the table below, for a minimum temperature difference between the streams of 20°C. Devise a heat exchanger network to achieve the maximum energy recovery. 

To design the network for maximum energy recovery start at the pinch and match streams following the rules on stream heat capacities for matches adjacent to the pinch. Where a match is made transfer the maximum amount of heat. 

Figure 23.42 shows an existing system that is set for maximum energy recovery, in which a new main is introduced away from the site pinch. The new main allows an increase in the steam generation and a change from steam use at a higher pressure to the new pressure. This has the... 

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