Every furnace should be monitored. The basic information (oxygen, draft, fuel usage, and feed rate) simply doesn’t motivate operators to make improvements. Two calculated variables, furnace efficiency and BTU per unit of feed, are much better at providing a target value for your process. Today’s packaged furnaces are an improvement over previous models but this is where automation has created a problem.
I’ve noticed over the past few years that operators ignore these furnaces unless the controls interfere with productivity. In one case, the operators didn’t like the heater’s slow response at start up, so they had it retuned to allow a higher air ratio. However, they didn’t bother to call the technician back to reduce the excess air once the unit was stable.
Enter the all-important Money Loss calculator. This ingenious line of software code compares current efficiency to ideal or target efficiency to calculate a fuel difference so it can display a “Dollars Lost” variable on the control monitor.
By having Money Loss calculators on all furnaces, you can easily pinpoint problem furnaces, units, operators, shifts or procedures. Setting unit goals would be easy as the dollars are always displayed for operators to watch. In most cases, you would give allowances for start ups, shut downs, and upsets, but then hold every operator accountable after that. The best part is that we’re talking real money and something that goes to the bottom line. It’s easy to understand and can be used to teach operators how to reduce the money lost.
Easily create a Money Loss calculator by establishing a furnace efficiency calculated variable and then comparing it to target furnace efficiency. Using current furnace efficiency, take your fuel rate and determine the fuel needed to run your process. From that number, calculate fuel use if at target efficiency. For example, let’s say that you’re using 100 million BTU/ hr of fuel at 72% efficiency and target efficiency is 80%. The fuel needed for the process would be 72 million BTU/hr (100 BTU/hr × 72% efficiency).
Fuel usage at target efficiency would be 90 million BTU/hr (72 million BTU /hr÷ 80% efficiency). So the fuel difference would be 10 million BTU/hr. Multiplying that amount by the cost of energy gives efficiency loss expressed in real dollars. In this case, if energy cost $8/million BTU, you would be losing $80 per hour or $700,000 per year. Operators may relate most directly if you express that loss by the shift — their report would include a $960 loss in fuel that shift (12 hours at $80/hr). So, maybe it’s worth it to get a trained person to retune that heater.
Money Loss needn’t be confined to heaters. Some Energy Management System software, used to optimize your entire system, can calculate loss between optimized energy efficiency and actual unit operations. This can include motor/turbine switching, steam balancing, furnace and water usage, condensate return and contract pricing. The software can calculate total loss and contribution of individual pieces of equipment. To run key equipment at optimum, individual calculators are very useful.
You can even extend Money Loss calculators to utility systems To track when water, nitrogen, chemicals, and air can usage exceeds optimum. By translating losses to dollars and making operators aware of costs, you’ll be surprised at how fast those losses can be reduced.
Now, I know a few of you have thought of the $1-million question: “how long will it be before the operators start ignoring the Money Loss calculator?” To sustain savings long term, you’ll need incentives. In most cases, you can use the calculators as part of performance goals, which usually are tied to bonuses or raises. Or have a contest between shifts or units with a winner picked each month to receive a prize. The money calculator is worth sustaining because it communicates on a level that everyone understands: dollars saved.
Gary Faagau is Chemical Processing's Energy Columnist. You can e-mail him at GFaagau@putman.net.