Energy loss audit

The major loss assessment components are discussed below. 

Heat loss assessment is conducted mainly based on temperature and pressure measurement. It is essential that a reference temperature be defined as the first step. The reason for defining a reference temperature in the energy loss audit is that heat above this temperature is considered as recoverable and thus accounted as loss if it is rejected to coolers. The typical reference temperature is 100 °F. The actual reference temperature to be selected for the heat loss calculation depends on the technical feasibility and economic viability for low-temperature heat recovery. 

On the other hand, other heat losses occur at relatively low temperatures. The question is what to do with such low-temperature heat. In general, there are a number of ways to recover low-temperature heat. One way is to use it for process heating such as feed preheating. In this case, a new heat exchanger may be installed to 

Equipment Services Process Temperature, °F In Out Duty, MMBtu/h 

Low Grade Heat Recovery Options Heat Sink Temperature, op Heat Source Temperature, °F End Use 

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An energy loss audit, as discussed here, seeks to identify key recoverable losses. The audit is relatively quick and is designed to determine improvement potential. If the energy loss audit identifies large energy losses, more detailed energy assessment efforts will be undertaken later if so required. Detailed assessment methods will be discussed in the later chapters. 

Table 3.2 Tabulated Energy Loss Audit Summary for the Example of Table 3.1...

The energy loss audit detected two major energy loss items Reaction effluent heat is rejected to the air cooler at 510 °F and stripper bottom product runs down in the water cooler at 470 °F, respectively. However, the energy loss audit could not determine the fuel-saving benefits of recovering these two heat losses and this question can only be answered by the heat recovery targeting assessment discussed later. 

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