Revised Model for Clean Cycle Optimization

TABLE 7.1. Sample Spreadsheet for Optimal Cleaning Cycle Based on the Simple Model 

In the second case, the value of k is reduced to 0.15 [°C/day] because heavy fouling exchangers were replaced with more advanced heat exchangers. At a lower fouling rate k, three effects can be observed  

The model described in the previous section assumes that the plant will shut down during cleaning of the exchanger train. This is usually not the case in reality where 

In the case that one train is cleaned while the other train continues to operate, the net margin in period 2 is no longer zero and therefore an extra term is introduced to equation (7.7) to yield 

This K can be negative when the cleaning cost is compensated by the unit margin made from the unit miming on one preheat train. 

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