Controlled Environment
Equipment Corporation
Controlled Environment
Equipment Corporation
A major Wisconsin food and Biofuels distilling and brewing facility successfully installed in late 2005 a RETOX Dual Chamber Regenerative Thermal Oxidizer (RTO) to achieve greater than 99% VOC abatement for their plant ethanol and alcohol VOC compliance. The 25,000 scfm RTO system was designed and manufactured by Adwest Technologies, Inc. of Anaheim, CA to meet not only the very high 99% VOC Destruction, but to also not generate any harmful nitrous oxide (NOx) byproducts due to the unique flameless operation of the RTO system.
Controlled Environment Equipment of North Prairie, WI, was the overall energy and environmental contractor for the Biofuels facility which also included interior plant capture, ductwork design and a high efficiency air to glycol fluid secondary heat recovery system that they integrated with the dual chamber RTO Oxidizer module. According to Dave Swinehart, VP at Controlled Environment "The RETOX RTO was selected due to Adwest's low pressure drop design which has 95% primary energy recovery for the RTO at full flowrate which provides our client with the lowest RTO energy usage. The RTO oxidizer's Flameless combustion was an added bonus in that no NOx byproducts are created since the burner is only used for the initial cold startup. The Adwest flameless RTO design with energy saving natural gas injection (NGI) has also been successfully installed for the past 20 years so we also are getting a market-proven mature VOC abatement system that is exceptionally reliable in meeting current and future EPA and state DNR air regulations".
Schematic A illustrates the simplicity of a typical two or dual chamber RTO Oxidizer system where the VOC laden process gas enters a forced draft fan. The VOCs the enter the RTO poppet valve flow control system which directs the VOCs into the first heat recovery bed where the they are then heated to 1500-1600 degrees F in the oxidation chamber where the VOCs are converted to water vapor. The solvent heat release of the VOCs that is liberated from the oxidization/combustion process are then adsorbed and stored in the second energy recovery bed. The poppet valve flow control system automatically switches the flowrate direction several times each hour so that both ceramic energy recovery beds store the energy for preheating the inlet VOCs. The RETOX Dual Chamber RTO provides self-sustaining operation at approximately 3% LEL inlet loadings without any external natural gas required. An integral PLC Control system with plant Ethernet capability provides automatic system monitoring and control while providing the plant with real-time energy usage, energy savings and VOC compliance.
Since the successful startup in late 2005 the regenerative thermal oxidizer with integral air to glycol coil heat recovery system has provided reliable VOC abatement while generating 3,000,000 btu/hr of secondary energy for the plant's drying processes. This recovered energy from the RTO Oxidizer exhaust is then utilized by the plant's internal drying process and product chilling systems. At the biofood plant's current natural gas energy price of $ 1.10/therm this unique secondary energy recovery system saves the plant over $33.00/hr in energy savings. In addition, the flameless RTO system with secondary heat recovery provides a reduction of over 3,000,000 pounds of carbon dioxide (CO2) Green House Gases (GHG's) making this biofoods processing facility one of the most efficient plants in operation today.
The bottom line according to Mr. Swinehart "is that his client is totally pleased in achieving high levels of VOC abatement while significantly reducing plant process drying and cooling costs while reducing green house gases to a minimal level." The RTO, duct, capture and energy recovery system were all designed with durable 316 stainless steel components and construction for long and reliable system life which also can accommodate potential acid gas condensation which is common in these types of biofuels and biofoods applications.
The Adwest RETOX dual chamber RTO system has an integral "bake-out" system, which is similar to a self-cleaning oven, that can volatilize and organic residue or condensables that are emitted from the process. Annual internal inspections of the RTO system have not shown any need at this plant for utilizing the bake-out feature.
This cost effective energy and environmental RTO Oxidizer system illustrates the importance to evaluate and design the VOC Abatement system integral with the plant /process energy recovery requirements. With the escalating cost of energy and fuel, many biofuels plants can achieve both successful EPA Air Compliance while possibly generating most, if not all of the process energy requirements for their facilities.
Let our experienced engineers design a cost-effective and efficient solution to control the VOC emissions at your facility. The action you take today may save you many thousands of dollars in years to come. Contact the CEE Engineering Department (262) 968-6565 or scampbell@CEE-corp.com.