Over the years of writing columns for Process Heating, I’ve had a number of items worth communicating that are just too brief to fill an entire column. This is a collection of those little bits and pieces. Just because something is small doesn’t mean it shouldn’t see the light of day.
Purple Polka DotsI wish waste energy were covered with purple polka dots. Then we’d have a hard time ignoring it.
Low-Hanging FruitThis phrase is beginning to wear out its welcome, like “Think outside the box” and all those other business clichés. In this case, I’m applying it to energy savings, where the plant engineer or energy manager says, “We’ve picked all the low-hanging fruit. Now we have to work hard to get additional savings.”
I’ve got news for you, pal: if you don’t maintain and tune your equipment on a regular schedule, all that low-hanging fruit will grow back. I guess that’s one way to look like a hero year after year.
Think Outside the BoxWell, you knew this was coming. If someone says you have to “think outside the box,” then the box is too darn small. Get a bigger box and put this saying to rest.
Top 3 Look Awfully FamiliarA long-time friend and former service tech once told me the three biggest factors in combustion systems going out of adjustment are:
Oh Yeah, Blame the AirFor years, those of us in this business have recommended tuning up combustion systems at least quarterly, partly to account for changes in atmospheric conditions. Some people pooh-pooh the effect of seasonal climate changes; others swear even small variations in temperature and humidity have a profound effect on their process heating operations.
So what’s the truth? Worst-case scenarios probably occur in temperate climates, like here in the upper Midwest, where summer days are hot and humid, and the air is cold and bone-dry in the depths of winter. Suppose a winter tuneup was done on a system fed by outside air at 20oF (-7oC) and 10 percent relative humidity. On a summer day where the air is 90oF (32oC) and 70 percent relative humidity, its density and, therefore, its oxygen content, will be only 85 percent of what it was when the system was set up. If the air-fuel ratio control system cannot compensate for this, the ratio will go richer (less excess air). A system set up for 10 percent excess air will go fuel rich (6 percent excess fuel), while one set for 100 percent excess air at the outset will drift down to 71 percent excess air.
The flip side of this is that a system set up in the Dog Days of summer will go leaner (more excess air) through autumn and winter. Ten percent excess air becomes 29 percent, and 100 percent excess air climbs to 134 percent.
Temperature change alone accounts for almost 98 percent of the difference. Humidity isn’t a big factor, except in very sensitive situations. Obviously, if the combustion air supply is drawn from inside the building, the temperature and ratio swings won’t be as drastic as these.
The Black Button SyndromeYears ago, I bought a good 35 mm camera. It was state of the art, bristling with all sorts of features, including a couple of little black buttons whose purpose is still a mystery. My wife and I went on vacation with some friends who took a prewar German camera that looked positively Stone Age next to ours. But was there any difference in the quality of our pictures? Not so you could tell.
What’s the point of this? When specifying control equipment, don’t let yourself be dazzled by a lot of bells and whistles you’re really not likely to use, and which may make setup and maintenance more difficult. Stick to the basics and get good at them. You’ll be way ahead of the game.
Works of GeniusWhich brings me to a more general observation, applicable in most of life’s endeavors: A mediocre plan, executed patiently and carefully, will beat the socks off a brilliant strategy, executed badly or not given the time to show what it can do. The Tortoise and the Hare are still with us.
I hope there has been something here you find worth remembering.