Specifying and selecting a regenerative thermal oxidizer (RTO) for control of your industrial process heating emissions can be a daunting task. Fortunately, there are tools available to increase your potential for success right from the start.
It does not require an in-depth knowledge of regenerative thermal oxidizer operation or features — at least not right away. What is critical, initially, is an understanding of details you already know well: your industrial process heating application and your business goals. Documenting these into an RTO specification will be a springboard for success. Table 1 will provide a useful guide for this effort.
Documenting your process conditions and your business goals will help ensure potential oxidizer suppliers will bid to the same baseline. Having easily comparable bids will simplify your proposal review process. It also will also help ensure:
- The RTO will be sized for the specific range of conditions expected now and in the future.
- Only necessary oxidizer features will be quoted by suppliers.
- Any RTO operating-cost comparisons can be based on your specific operating conditions.
- A clear project scope — that is, oxidizer location, a specification for included ductwork and the like — is used to ease turnkey project-cost comparisons.
The permitting process is not addressed in this article, but I recommend early involvement by your in-house environmental engineer or an outside consultant. Their knowledge of regulations specific to your locale, facility and process will be valuable for the development of an emission compliance plan — necessary both now and in the future.
Analyzing Regenerative Thermal Oxidizer Proposals
Once proposals are received based on your specification, the next step is evaluating the various proposed regenerative thermal oxidizers for suitability and long-term performance. What should be considered in the evaluation process?
An important criterion for selecting a regenerative thermal oxidizer design — and supplier — is proven experience in your specific application. An application with highly condensable VOCs or multiple hot and cold airstreams mixing may not be well suited for the RTO supplier/design that has focused on one-source applications at ambient temperature with low flashpoint VOCs. Being the end user who is the “learning curve” for an RTO design or supplier can be painful.
If an RTO design meets the experience metric, a more in-depth analysis should be made, beginning with the major components of the oxidizer system. These components must be assessed individually and as a system. Table 2 looks at the components that make up an RTO system, and it provides guidance on their importance and possible questions to ask.
An example will help illustrate the process. Also included in table 1, in the column labeled Source 1, are the hypothetical process conditions and growth plans we will use to select a regenerative thermal oxidizer.
This hypothetical application is simple, with no particulates or halogens in the airstream and light VOC concentrations. A standard rotary or poppet valve RTO without additional features will be the offering of most suppliers. Insulated valves and ductwork will be suggested due to 225°F (107°C) temperature.
Based on these application details, the likely recommendation for the hypothetical application is a 17,000 scfm capacity RTO with insulated/clad poppet or rotary switching valve; structured or random ceramic media; fuel injection; mild steel construction; and insulated ducting/valve. The size recommended (17,000 scfm) addresses the two-year growth plan. Planning for four years out has too many unknowns.
Because a regenerative thermal oxidizer with poppet valves will perform as well as a rotary valve RTO for Source 1, the switch valve selection can be based on value. The ceramic media bed designs must be evaluated individually. Secondary heat recovery has potential ROI because the RTO exhaust temperatures will be above 300°F (149°C).
In conclusion, successfully navigating the selection of your regenerative thermal oxidizer (RTO) from specification through proposal review does not have to be overwhelming. These simple checklists will help you build a well-thought-out RTO specification and also guide a methodical review of RTO proposals. With these checklists, your team and any needed outside environmental engineering support can assemble a clear, forward-looking plan for your current and future emission control needs. This specification then provides a solid baseline that RTO suppliers can quote from — and will thank you for — and it will ease your proposal review process.
Review the proposed RTO components/system with the second checklist to differentiate one RTO system from another. This will help you evaluate each RTO from a position of knowledge and understanding, allowing you to ask informed questions of each supplier. These checklists and guidelines are not all you will need, but they do provide high level maps to guide your efforts.