Energy Performance Index EPI Method

What about the FE for vented LP steam In this case, FElp should also be calculated based on the path from which this vented LP steam is generated. This is because a certain amount of fuel equivalent is consumed to make the LP steam no matter whether it is used or vented or not. For vented LP steam, the economic value is zero but FE is not. 

4 FE for Condensate Condensate temperature is typically around 200 F. The condensate FEcond can be determined by the difference of condensate temperature and raw water temperature (ambient). FEcond is usually in the range of 100-150 Btu/lb of condensate. Although FEcond is small relative to steam, accumulated loss could be significant for a large amount of condensate loss. Also, condensate loss is costly due to the extra chemicals required to treat makeup water. 

5 FE for BFW Water The energy required for providing boiler makeup water includes the heat content and the pump power used to elevate its pressure. The BFW heat content is the major portion of FEbpw. which is determined by the difference of BFW temperature (typically around 250 °F) and raw water temperature (ambient). The FEbfw is in the range of 150-200 Btu/lb of BFW. 

Naturally, one would think that the first and second laws of thermodynamics should be used as methods for assessing energy efficiency for industrial processes. If we 

Clearly, this efficiency is not very insightful as energy input is provided at very high quahty in terms of temperature, pressure, and composition, while the energy losses are at a much lower quahty however, they are compared on the same basis. 

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