RTO rule-of-thumb calculations / Energy planning

RTO Operating Cost Estimator

Explore how airflow, operating hours, fuel price, VOC heat contribution, and heat recovery affect estimated supplemental fuel cost.

This preliminary tool extends SSE’s published rule-of-thumb example at 1,500°F. It estimates steady-state fuel cost only. Startup fuel, fan electricity, maintenance, installation, and other costs are excluded. Use the result to start a project discussion, not to set operating conditions or size equipment.

Your operating scenario

Example values are editable. Enter your delivered fuel price; the default is an illustration, not a market-price forecast.

Standard cubic feet per minute; do not substitute ACFM.
Steady-state operation, 0–8,760 hours.
Multiply a USD/therm rate by 10 to obtain USD/MMBtu.
Use an engineering estimate or measured basis.
A scenario to evaluate, not a promised upgrade outcome.
Include known VOC heat contribution

If this information is unknown, leave VOC mass flow at zero. The model will apply no VOC fuel credit.

13,000 is the legacy alcohol/acetate example. Replace it with a suitable value for your mixture.

Your indicative fuel estimate

Select Calculate Fuel Cost to see your result.

This is a simplified planning model, not a performance guarantee or a complete operating-cost estimate. Review the assumptions below.

Your estimate is added to the inquiry below when you choose this button. Nothing is sent until you submit the inquiry.

How the estimator works

The calculation uses SSE’s legacy assumption of 28.24 Btu per standard cubic foot at 1,500°F, neglects inlet sensible heat, and adds 10% to the unrecovered sensible-heat load as a simplified heat-loss allowance.

Heat load (MMBtu/hour) = airflow × 60 × 28.24 × (1 − heat recovery/100) × 1.10 ÷ 1,000,000.

VOC heat credit (MMBtu/hour) = VOC mass flow × VOC heating value ÷ 1,000,000. Estimated supplemental fuel = the greater of zero or heat load minus VOC heat credit. Annual fuel cost = supplemental fuel × fuel price × operating hours.

The model assumes the entered VOC heating value is available as useful heat. It does not model combustion efficiency, moisture, composition-dependent heat capacity, dilution air, air leakage, burner turndown, purge cycles, thermal cycling, or hot-bypass effects. Actual requirements can differ materially. A zero result does not establish safe autothermal operation or zero total fuel consumption.

How this compares with the original worked example

At 10,000 SCFM and 95% heat recovery, the unrounded load is 0.93192 MMBtu/hour. For 60 lb/hour of VOC at 13,000 Btu/lb, the heat credit is 0.78 MMBtu/hour, leaving 0.15192 MMBtu/hour in this model. The original sheet rounded 1.5532 Btu/scf to 1.6 before multiplying by flow, producing 0.18 MMBtu/hour. This estimator keeps full precision until displaying results.

View SSE’s original calculation sheet (PDF). Its example is a screening calculation, not an equipment specification.

Turn an estimate into an engineering decision

Fuel use is one part of the decision. Review airflow, production changes, media condition, pressure drop, controls, and startup frequency before choosing an upgrade. Compare repair, retrofit, and replacement, explore custom RTO systems, or discuss ceramic media replacement and upgrades.

Have SSE review your operating-cost estimate

Share your facility location, process, and project timing. Use the estimate button above to include your assumptions and results. Complete technical specifications are not required to start.

Prefer to talk? Call 562-997-0233. Please do not include confidential process documents in this initial inquiry.

  • This field is for validation purposes and should be left unchanged.
  • Optional. Include your country code if you would like us to call you.
  • Tell us about your process, facility location and project timeline. Airflow or emissions data is helpful if available.

We review your inquiry, clarify the available operating data, and discuss the appropriate engineering evaluation and proposal scope.