RTO Glossary / RTO Engineering & Upgrades
Secondary Heat Recovery in RTO Systems
Secondary heat recovery captures available thermal energy beyond the RTO’s internal regenerative heat-recovery function and transfers it to a suitable external process or utility demand.
What Secondary Heat Recovery Means in an RTO
The ceramic beds primarily recover heat to preheat incoming exhaust and reduce the oxidizer’s own heat demand. Secondary recovery asks a different question: whether remaining usable energy can serve another load, such as a compatible air-heating or water-heating duty.
Not every RTO has useful surplus heat. The available amount and temperature change with inlet conditions, solvent loading, internal recovery, and operating mode. The receiving process must need the heat at the time it is available.
For application-specific context, explore Expanded polystyrene manufacturing and Ship & Shore’s Heat recovery and heat exchangers.
Why Secondary Heat Recovery Matters
A recovery project succeeds when useful energy displaces a real utility demand. Nameplate heat duty is not the same as annual savings. Account for production hours, heat-user availability, exchanger performance, added resistance, controls, maintenance, and installation cost.
| Engineering distinction | What it means | What to review |
|---|---|---|
| Primary regenerative recovery | Reuses heat within the oxidizer | Evaluate ceramic-bed thermal performance. |
| Secondary recovery | Transfers available heat to another demand | Identify the receiving process and useful temperature level. |
| Annual useful recovery | Energy actually used over time | Match source availability with the heat-user schedule. |
Engineering Considerations
Evaluate the term against the actual process and installed equipment. Useful review inputs include:
- Actual available heat across production modes, not only at peak load.
- Required temperature and duty of the proposed heat user.
- Overlapping schedules and seasonal changes in demand.
- Materials, fouling, corrosion, pressure drop, and control integration.
- Measured baseline, installed cost, maintenance needs, and verification plan.
Practical RTO Takeaway
Start with the heat user. A recovery opportunity has commercial value when available energy can reliably replace an existing demand without compromising the emissions-control system.
How This Shows Up in the Field
SSE’s EPS energy-recovery case study describes reuse of stack heat within the facility. It provides application context, not a transferable savings guarantee; a new project needs its own heat balance and evaluation of coincident demand.
Related project: EPS energy recovery case study. Project examples describe the cited installation; equipment suitability and results for another facility require their own engineering review.
Secondary Heat Recovery FAQ
How does secondary recovery differ from RTO thermal efficiency?
RTO thermal efficiency concerns internal heat reuse, commonly through ceramic media. Secondary recovery concerns heat delivered to an external demand. The two metrics should not be combined or substituted without clearly defining their basis.
Can secondary heat recovery be retrofitted?
Potentially. Evaluate the available thermal duty, receiving process, equipment materials, flow resistance, controls, and site installation constraints. A retrofit must preserve the oxidizer’s required operating conditions.
How should savings be estimated?
Estimate useful delivered heat over actual operating hours and compare it with displaced energy on a consistent efficiency and cost basis. Include added electrical demand, maintenance, downtime, and heat-user availability.
Is there a useful heat demand near your RTO?
Share the heat-user requirements and operating schedules with Ship & Shore Environmental to discuss the feasibility of secondary recovery.
Related Ship & Shore Resources
SSE secondary heat recovery guidanceAdditional application context for using recoverable oxidizer heat.
Expanded polystyrene manufacturingProcess-specific exhaust collection and pentane-control considerations.
EPS energy recovery case studyAn example connecting VOC treatment with a useful facility heat demand.
Related RTO Glossary Terms