如何解析自考市场营销学.ppt

Heat work Designone aspect of process integrationJ. M. ShawInstructor CHE 465I would happily credit the authors who provided the example but am unable to do ?Process integration provides a discipline which allows designers to establish–The minimum energy to operate a process–A process design with the lowest energy intensity–An optimal investment strategy?Design decisions are made consciously and consistently. Global capital and operating cost implications and trade-offs e visible.?We will focus on the first bullet only and will introduce the terminology of the discipline as we go along!Start with a flow sheet without heat exchangers installedIdentify streams that require heating called “cold streams” and streams that require cooling “hot streams.”Without heat recovery we require 750 units for heating cold streams (steam?) and 660 units for cooling hot streams (cooling water?).pute the minimum energy required to operate the pute summary heating and cooling needs for the process. Do this step by step to avoid errors!These are called “composite curves”for heating and cooling is the theoretical minimum energy required to operate the process as designed?Think of your process as a single giant counter current heat exchanger with an infinite surface area!The minimum approach temperature of the hot and posite streams is 0 C! The temperature at which this occurs is called the “pinch”– 70 C in this that cannot be supplied by exchange must be supplied by utilities: ~ 200 units for heating and ~ 110 units for closely can this minimum energy requirement be approached in practice?Our analogy with a heat exchanger still holds and we establish a minimum approach temperature for posite streams, in this case 20 C, that arises around the units for heating and 210 units for cooling!Pay twice for inefficiencies! Heating and cooling requirements rise together!How do we translate these concepts into practical heat work de