Introduction

The main objective of energy efficiency optimization is to minimize the energy consumption and cost. This is usually done by increasing the energy efficiency of the system/subsystems and equipment and optimizing the process parameters to achieve the desired objective within the operating constraints. Some of the means of achieving the desired objective are

• Optimal energy mix

• Optimal process mix

• Optimal process parameters

These allow for minimum energy cost while meeting all the production targets in quality and quantity. This chapter describes these features of energy efficiency optimization, using practical industrial examples.

Energy Mix Optimization

At the micro level, a number of energy resources are used by the process and power industry to meet the required energy conversion into steam and power, among other products. These energy resources include coal, lignite, fuel oil, fuel gas, waste heat, imported utilities like steam and power, and organic wastes. At the macro level, the energy resources used are fossil fuels, hydel power, nuclear power, natural gas, and nonconventional energy.

At the industrial level, a number of options are available to meet the energy demands of the process, which are evaluated during the process design stage. Each energy resource has an associated cost, and hence, there exists a need to optimize the energy input resources such that the total energy cost is minimum. This refers to the case of a fired heater used for the processing of crude oil in a refinery.