Could we use the waste heat from an RTO?

13. Could we use the waste heat from an RTO?

RTO’s are designed to be energy-efficient within themselves. Although the combustion temperature typically is around 800-850oC, the highly efficient heat recovery by the ceramic media means that only low-grade heat being emitted at around 100oC is normally available. This heat can be used for example via a heat exchanger for simple heating to warehouses and storage areas.

If levels of solvent are consistently high (typically above 2.5 g/m3) then the burner in the RTO would switch off in order to maintain the desired operating temperature, i.e. the unit becomes autothermal or self-sustaining. As the solvent levels increase (e.g. >4-5 g/m3) then excess heat is generated which usually is released from the combustion chamber directly to the stack via a high solvent bypass without recovering the heat, again to maintain the combustion temperature set point. If this situation occurs regularly, the high grade heat can be used for heat recovery for example to thermal oil.

Thermal oil heat recovery in a high temperature bypass of an RTO

The loading must however be assessed carefully to ensure that only excess heat is used. If not, then the RTO burner can be used as a primary heat source which is not energy-efficient.

The Carbon Trust could support such installations with interest-free loans - EPM Consultancy are registered with the carbon Trust and can assess the viability of various options for you.

If you would like to discuss any aspect of the information outlined in this question, please contact EPM at contact@epm.uk.com.

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