Energy Management

Implementing the next phase of an energy audit

This article explores the implementation and sustaining phases of an energy audit.

By Ven V. Venkatesan

Once an energy audit team presents its findings, along with a prioritized list of actions, decision makers must decide which — if not all — recommendations should be implemented. (Keep in mind, unless the cost benefits of the recommendations are attractive, decision makers will focus on other compelling budget priorities.) Then, for those projects getting the go-ahead, the third phase of the energy audit cycle can begin.

Implementing phase: The first step in the third phase of the energy audit cycle (Phases 1 and 2 were highlighted in last month’s column) is to develop an implementation plan. Each team should include members from relevant disciplines. Some recommendations, such as fixing steam leaks and reducing excess air levels at the fuel-fired boilers and heaters are straightforward and require obvious actions. These projects can be started quickly, typically yield quick results, and require zero or little capital investment.

For instance, in a graphite plant that molds and bakes calcined petroleum coke powder into large-sized electrodes, an energy expert attempted to control excess air at one of several baking furnaces to record the best-achievable operational settings. Because the baking cycle undergoes several stages of heating over a 72-hr period, a portable flue gas analyzer, along with the recordings of the existing on-line flue-gas oxygen analyzer, monitored and adjusted hourly the excess air level. Due to its capability of measuring the CO and combustible gas contents in flue gas, the portable flue gas analyzer trimmed the oxygen levels. A fuel-oil flow totalizer also recorded hourly readings from the baking furnace. This oxygen-trimming exercise resulted in developing a chart of operational settings for the baking furnace that established just 5% excess air achieved complete combustion at some stages of the baking cycle. The exercise also reduced fuel oil consumption 12% compared to the average fuel oil use per cycle recorded earlier in that same furnace.

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