الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 112 |  |  |
| | | from | 112 | | |
Abstract
Energy optimization has become a priority for industry because of energy high cost as well as environmental concerns. This thesis presents a systematic approach for heat exchanger network retrofitting to maximize energy recovery in industrial plants (refineries, chemical and petrochemical). Additionally, it introduces unconventional solutions through energy and utility optimization for some equipment, such as steam generation, Organic Rankine Cycle (ORC) and absorption chillers. These techniques (waste heat recovery) increase heat recovery and decrease utility consumption through using the excess heat. If this heat is a high-grade heat, it can be used for steam generation. If it is a low-grade heat, it can be used for absorption chillers to produce chilling water or Organic Rankine Cycle to generate electricity. The introduced methodology focuses on practical energy reduction that can be achieved in process plants; complex modifications are excluded unless the resulting energy reduction required it. The reliability of the considered approach is examined individually at each proposed modification. The proposed methodology begins with identifying maximum possible energy reduction using pinch analysis to decide either to proceed with retrofit or not. There are two main steps in this approach; the first is to perform the heat exchanger network suggested modification such as re-piping, resequencing, stream splitting, heat exchanger addition, etc., while the second is to apply waste heat recovery techniques such as absorption chillers, Organic Rankine cycle (ORC) and steam generation. Many energy reduction alternatives are presented to select the best one, based on the nature of each plant, which can be needed for chilling or electricity. The preheat train of a crude distillation unit (CDU) is used as a case study to demonstrate the effectiveness of the proposed approach. The present approach results show a reduction in energy consumption with minimum changes in topology compared with energy consumption estimated by using pinch technology. The energy reduction after applying the traditional retrofit (1st step) is 10% for hot and cold utilities, respectively. waste heat recovery techniques reduced 62.5% in the cold utility. The results show that the duties of fired heater, air coolers and water coolers are deceased by 10%, 81%, and 62% respectively. Moreover, low pressure steam (LPS) generation is increased by 54%. in terms of economic analysis, a total savings of 6,512,866 $/yr is expected with a payback period 1.16 yr.