RCO vs. RTO Fuel Costs: What Determines the Difference?
Does an RCO Always Use Less Fuel Than an RTO?
No single oxidizer configuration has the lowest fuel cost for every application. A catalytic oxidizer can require less burner energy because the catalyst promotes oxidation at a lower temperature. A regenerative thermal oxidizer (RTO), however, can recover a high proportion of heat from the treated exhaust. The result depends on the complete process duty rather than operating temperature alone.
For this comparison, HiTemp recuperative catalytic oxidizer means a catalytic system using an air-to-air heat exchanger. This distinction matters because RCO commonly means regenerative catalytic oxidizer elsewhere in the emissions-control industry.
How the Two Configurations Differ
| Cost factor | HiTemp recuperative catalytic oxidizer | Regenerative thermal oxidizer |
|---|---|---|
| Oxidation method | Catalyst promotes oxidation at a lower reaction temperature | Thermal oxidation without a catalyst bed |
| Heat recovery | Air-to-air heat exchanger preheats the incoming stream | Ceramic media beds alternately store and release heat |
| Primary fuel advantage | Lower required reaction temperature for a compatible stream | High regenerative heat recovery during stable operation |
| Potential penalties | Catalyst replacement, fouling or poisoning; exchanger pressure drop and fouling | Valve switching, purge losses, media pressure drop and maintenance |
| Important stream limits | Catalyst compatibility, particulates, aerosols and catalyst poisons | Particulates, condensables, corrosive compounds and media plugging |
What Determines Actual Fuel Cost?
A useful comparison calculates burner demand over the same airflow, contaminant loading, operating schedule and required destruction efficiency. At a minimum, the analysis should include:
- normal, minimum and maximum exhaust airflow;
- inlet gas temperature, oxygen and moisture;
- VOC and HAP species, concentrations and variability;
- required chamber or catalyst inlet temperature;
- verified heat-recovery performance across the operating range;
- heat loss, leakage, purge and cycle losses;
- startup, shutdown, standby and turndown operation;
- burner efficiency and fuel heating value; and
- annual operating hours and delivered natural-gas price.
Annual burner-fuel cost is based on the quantity of fuel consumed, its heating value, operating time and the applicable delivered rate. Natural gas does not lose half of its billed energy value merely because the oxidizer operates at a high temperature. Fuel comparisons should use the same billing and energy basis—such as dollars per therm or dollars per million Btu—for both alternatives.
How VOC Loading Changes the Comparison
VOC oxidation releases heat. As inlet concentration rises, that heat can reduce auxiliary burner demand and may allow an oxidizer to approach autothermal operation. At lower or highly variable concentrations, heat recovery and turndown performance become especially important. Safety limits, including the allowable fraction of the lower explosive limit, must also be incorporated into the design.
Fuel Is Not the Only Operating Cost
A lifecycle comparison should also consider fan electricity, pressure drop, catalyst testing and replacement, heat-exchanger or media cleaning, valve and seal maintenance, downtime, spare parts and monitoring obligations. A lower calculated fuel rate may not produce the lowest total annual cost if other operating or maintenance requirements are materially higher.
RCO and RTO Cost Questions
What Information Is Needed to Compare RCO and RTO Fuel Costs?
A defensible comparison requires normal and maximum airflow, inlet temperature, VOC species and concentration profile, required destruction efficiency, operating temperatures, heat-recovery performance, operating hours, startup frequency, fuel heating value and delivered fuel price.
What Does RCO Mean?
RCO commonly means regenerative catalytic oxidizer. HiTemp has also historically used RCO for a recuperative catalytic oxidizer with an air-to-air heat exchanger, so the configuration should be stated explicitly in specifications and cost comparisons.
Learn more about HiTemp recuperative catalytic oxidizers, catalytic oxidizer systems and thermal oxidizer systems. For a project-specific energy comparison, contact HiTemp Tech Corporation with the available process data.