(105c) Exergy Destruction Effect on GHG Emissions in Industrial Process Heaters

This paper addresses the process heaters GHG emissions due to different levels of entropy generation. Factors affecting and playing a significant role in the enhancement of the process heater efficiency are focused on.

The importance of furnace efficiency calculation is recognized by all process engineers. The calculation of thermal and exergetic efficiency is important because it evaluates the furnace performance and shed some lights on what to do to improve it. Understanding the fundamentals of furnace calculations provides a structure for engineers aiming to gain information and understand operation. Many researchers shown in many papers how the thermal efficiency is calculated using flue gas analysis. However, few papers are published using the second law analysis especially for large industrial heaters. The method introduced here considers fuel gas analysis and stack temperature to calculate the exergetic efficiencies. In recent years irreversibility (sometimes referred to as Entropy Generation) and availability (sometimes referred to Exergy) are getting grounds day by day now since they are vey powerful in analyzing complex thermodynamic systems such as fired heaters as shown in this paper.

The main objective of this paper is to introduce simple exergy analysis for the industrial process heater, calculate its thermal efficiency and GHG emissions using the second law of thermodynamics. All chemical reactions of more than nine fuel components taking place in the burner have been analyzed. The exergy destructed (availability lost) and ýentropy generated from the heat and mass flows in the process heater sections (burner, radiation section and convection section) have been investigated. Thermal design modifications in order to improve the efficiency of the process heater and consequently GHG emissions are suggested. In addition recommendations are developed for the operation of process heaters for efficient use of fuel and less GHG emissions. These recommendations are applicable in any industrial facility.