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FLEXO Magazine : March 2009
TECHNOLOGIES & TECHNIQUES Take the Heat... and Reuse it Solutions for Reducing Operating Costs Using Oxidizers By Mike Scholz T he mainstream media today is full of allusions to energy awareness and conservation. Just as visible these days are media references to astronomical dollar figures that can boggle the mind. This article does not seek to break out of that mold, but rather to conform to it. Oxidizer stack heat recovery of- fers a tremendous opportunity for both energy conservation and energy cost reduction. Consider the following: . At any hour of the day there are likely to be more than 10,000 oxidizer systems in service, using a high-temperature reaction chamber (with or without catalyst) to treat the ex- haust gases from a wide range of industrial processes. · The final component of nearly all of these oxidizer systems is an exhaust stack, where the treated exhaust gases are re- leased to the atmosphere at elevated temperatures. · Historically, oxidizer systems have been sized to treat ex- haust airflows from 100SCFM (Standard Cubic Feet per Minute) up to several hundred thousand SCFM. But con- servatively, the average oxidizer system airflow processing capability (i.e. size) can be estimated to be between 15,000 and 20,000SCFM. · Now, considering these 10,000 stacks emitting hot, treated gases to the atmosphere around the clock; if heat recovery equipment capable of dropping the exhaust stack tempera- - ture by 100 0 F could be installed into each one of them, this would lead to an overall value of over 18 billion BTUs (British Thermal Units) per hour of energy conservation! · In dollars, assuming $lo/MMBTU and year-round operation, this equates to recovering over $1.5 billion worth of energy per year! Taking this into account, it is no surprise that a wide range of stack energy recovery options have been developed and marketed to end-users of oxidizer systems. This article will discuss three important aspects of energy reclamation from hot oxidizer stacks: 1. Energy reclamation from oxidizer stacks is one of three potential areas of optimization for oxidizer systems. 2. There are distinct challenges that must be addressed in the process of evaluating potential energy savings options. 3. There are multiple potential equipment options for this ap- plication, each with its own benefits and limitations. ABC'S OF OXIDIZER STACK ENERGY RECOVERY Using ABC's in the title of this section is actually a misnomer. Truthfully, it should say CDE's. The reason for this is twofold: First of all, any plan for recovering waste heat in the exhaust stack of an oxidizer system is already a Plan C. For anyone taking a hard look at optimizing the energy efficiency of an oxidizer sys- MARCH 2009 www.flexography.org FLEXO
Sustainable Winter 2009