Cost model · BeamStack® in-situ cross-stack vs zirconia probe
Fuel saved by trimming excess oxygen
Lower excess oxygen means less heat carried out of the stack by air you did not need to heat. This model prices that saving on your plant. It is the only one of our cost models where the argument is fuel rather than instrument cost, and where the saving can be far larger than either instrument.
Plant
Rated capacity is not fuel consumption. The model converts one to the other using your load factor and boiler efficiency, so enter the nameplate rating here rather than an estimate of what you actually burn.
Combustion
The efficiency figure below is a rule of thumb, not a constant. The gain per percentage point of oxygen removed rises with flue gas temperature and with the starting oxygen level, so a plant with a hot stack recovers more than one with a cold stack. Use your own figure if you have one from a combustion survey.
Zirconia probe
BeamStack® cross-stack analyzer
Shared assumptions and financing
Enter your figures above
The model runs as soon as the fields are filled.
Annual fuel bill
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Annual fuel saved
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Extra capital over zirconia
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including installation
Net position over horizon
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present value
Cumulative net position, present value
Net position, BeamStack against zirconia Break-even line Payback
| Line | Zirconia | BeamStack | Difference |
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Method. Fuel input in MWh is rated capacity multiplied by operating hours and load factor, divided by boiler efficiency. The fuel bill is that figure multiplied by your fuel cost. The saving is the fuel bill multiplied by the oxygen reduction and the efficiency gain per percentage point. Capital and installation fall in month zero, fuel savings and service costs accrue evenly across the year, and everything is discounted to present value at the rate you set.
The chart is drawn to scale. The saving is a small percentage of a large number, and it looks like a small percentage of a large number, because a chart that exaggerated it to make it visible would not be worth showing you.
What this model does not decide. Whether your plant can hold a lower oxygen setpoint is a question about the burner, the turndown range, the control loop and the fuel, and it is answered by a combustion survey rather than by an analyzer datasheet. This model prices the saving if the trim is achievable. It does not establish that it is, and it is not a substitute for burner commissioning. The starting values are illustrative placeholders, not published prices for any product and not a quotation for any competing instrument.
