Thermal Pinch Analysis

Introduction

Energy Efficiency has become one of the important factors to consider in designing chemical processes due to the trending energy prices, limited fossil fuel resources and strict environmental regulations being applied worldwide. It has become important to increase processing energy efficiency in order to improve overall production economics of existing plants and new designs as well. (1),me.
Heat integration and optimization is a reliable method for energy conservation and energy efficiency. It uses heat sources and sinks in the plant within the plant and utilizes it to the maximum thus reducing external cooling and heating with the relevant cost and emissions. It has several definitions, almost invariably referring to the thermal

Pinch Analysis is a methodology for minimizing energy consumption of processes by calculating thermodynamically feasible energy targets (or minimum energy consumption) and achieving them by optimizing heat recovery systems, energy supply quality and process operating conditions. It is also known as "heat integration", "energy integration" or "pinch technology“. The main target of the present work is to review pinch analysis as a technique for heat recovery explaining its strengths and limitations and introduce the concept of beyond pinch which is a new methodology developed by GAP-Tech from its experience in energy conservation and process optimization.

It first identifies sources of heat (termed hot streams) and sinks (termed cold streams) from the material and energy balance. (3, Smith)
Pinch analysis is an integral part of the overall strategy for process development and design, often known as process synthesis, as well as the optimization of existing plants. The process design hierarchy can be represented by the “onion diagram” shown in figure 1. Using Pinch Analysis, it is possible to identify appropriate changes in the core process conditions that can have an impact on energy savings (onion layers one and two). After the heat and material balance is established, targets for energy saving can be set prior to the design of the heat exchanger network. Figure 1 : Onion Diagram

A key concept of pinch analysis is setting energy targets. These targets are absolute thermodynamic targets, showing what the process is inherently capable of achieving if the heat recovery, heating and cooling systems are correctly designed.