What is an RTO – Regenerative Thermal Oxidizer?
A regenerative thermal oxidizer (RTO) is an essential element in any facility that performs operations that produce industrial process exhaust. RTOs are responsible for cleansing the environment of air toxins, odors, volatile organic compounds (VOCs), and hazardous air pollutants (HAPs) that can be detrimental to one’s health, work environment, or production itself. RTOs are found in a wide variety of industries that perform procedures that require ventilation ranging from waste management facilities and chemical plants to food processing and vehicle manufacturing factories.
The way RTOs work is by utilizing ceramic material to absorb heat from industrial exhaust gas and using it to preheat incoming gas. The RTO uses this stored heat to kill off any pollutants in the air discharged from process exhaust streams at a temperature ranging anywhere from 815 °C (1,500 F) to 980 °C (1,800 F).
The Purpose of Dampers for Your RTO
Industrial dampers (or valves) in a regenerative thermal oxidizer system are there to supply tight shut-off of process air to maintain destruction and removal efficiency (DRE) and appropriate heat exchanger operation thermal energy recovery (TER). Industrial dampers regulate airflow and allow for isolation of ducting and other equipment for maintenance purposes.
Choosing the right industrial damper for your RTO is imperative for maintaining optimal efficiency over a long period of time. Considerations such as maximum system pressure, air type, system design, temperature changes, and any stressors must be taken into account when selecting your custom industrial damper to maximize your RTO usage and maintain efficient VOC destruction. At Flexcom we’re determined to provide our customers with the appropriate custom industrial damper for your regenerative thermal oxidizers based on research, experience, and industry needs.
Butterfly Industrial Dampers for RTOs
The standard for RTOs for over 30 years, Butterfly Industrial Dampers inhabit less space than other valves and are extremely versatile owing to their design. These custom industrial dampers utilize a solid center-mounted rotating disc (or discs) that turns 90 degrees (activated by an actuator) for opening and closing to control the gas stream flow. In the closed position it blocks close to the entire stream flow (approximately 99.75% of airflow), and in open provides little in the way of flow restrictions. They are reliable in both modulating and on-off applications.
Butterfly industrial dampers require relatively low operating torque requirements while maintaining a fairly tight seal in closed positions. While the size and type of the custom industrial damper will determine torque and actuator requirements, the butterfly industrial damper is known for its versatility and effectiveness. The industrial butterfly dampers used in RTOs are the on-off type. Multi vane dampers are typically rectangular or square and can have several vanes or blades. These dampers can withstand temperatures up to 2000 degrees fahrenheit.
Poppet Industrial Dampers for RTOs
Initially created for use in fabric filter systems, poppet industrial dampers were later used in RTOs and have been ever since (for over 15 years now). Activated by an electric or pneumatic actuator the custom poppet industrial damper is a flat circular plate that is raised and lowered to press against or move away from a cylinder shaped seat. In the closed position gas seeking to flow past the cylinder is blocked, and in the open position there’s a one to two foot gap between the cylinder opening and flat plate.
Flexcom’s custom poppet industrial dampers are not for use in modulating applications. These are meant for on-off control only.
In RTO’s, poppet industrial dampers are particularly advanced sealing several gas paths while redirecting gas in various directions simultaneously. These dampers are activated by pneumatic or hydraulic cylinder actuators that provide high-cycle service and low-leakage isolation – poppet industrial dampers with zero-leak blades and seats are available as well. Poppet valves with three and four-way configurations are also common in some RTOs. A three-way poppet has one inlet and two outlets and cycles between two seats diverting flow through one while sealing the other. And four-way poppet dampers have two inlets and two outlets.
Hot Side Industrial Dampers (Bypass Dampers)
While most regenerative thermal oxidizers operate at temperatures ranging from 1800º-1850º F, there are times when the heat may exceed that limit. For this reason installing a hot side industrial damper (or bypass damper) is an integral step for securing your RTO. A bypass damper will control the core temperature of your RTO and support it in maintaining a consistent temperature. Note that if temperatures in your RTO do not remain consistent, it will not convert gases and result in minimal heat recovery and conversion. This can also result in your RTO shutting down.
A hot side damper is vital under conditions where the level of volatile organic compound (VOC) concentration increases and pushes temperatures above their limit. When this occurs a variable energy-recovery (VER) system will activate the bypass damper opening it up to control the temperature. As the bypass damper opens, some of the hot gas from the burner chamber is diverted from the heat-exchange beds, thus regulating the temperature.
For more information on dampers in general please refer to Flexcom’s Industrial Dampers page.