Comparing Costs Of Flameless Oxidation To Flame Oxidation

Description

Flameless Regenerative Thermal Oxidation is a destructive technology for off or waste-gas treatment of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). The method converts VOCs to carbon dioxide, water without treatment of the vapors to any flame. The technology attains thermal oxidation of VOCs using heated packed ceramic pieces. The vapors are oxidized when they travel through the heated ceramic media bed.

Comparisons

When comparing regenerative thermal oxidizers there are several different methods used in initiating the pre heat stage of operation. Some regenerative thermal oxidizer systems have used heating elements as the source to elevate the temperatures to destruction levels, while others use burners or (after the pre heat stage) turn the burners off and inject natural gas as part of the emission stream to influence the rise in temperature. These are called flameless regenerative thermal oxidizers.

Electric systems have been around for some time, however for larger systems over 10,000 SCFM many have proven to be a non-stop maintenance nightmare with element failure, constant element replacement, ceramic media melting and equipment down time. Developments in electrical element technology may soon make this technology more viable. However, with the reduction in price of natural gas, further progress may be insignificant or may only be utilized in countries which have limited natural gas quantities.

Many times, regenerative thermal oxidizers being exported outside the U.S market will pre heat the regenerative thermal oxidizer systems using propane, plant tail gas, or diesel fuel as the source of Btu’s to bring the equipment up to temperature. Regenerative thermal oxidizers are very resilient and as such are able to pre heat and maintain temperatures using many types of Btu types and supplies.

Whatever energy source used to supplement and sustain necessary temperature to achieve thermal destruction, it can become costly. Many manufactures have tried various techniques and some methods have proved to be viable while others are simply fuel hogs.

One such fuel hog is the flameless regenerative thermal oxidizer. The terminology emphasizes that no additional fuel would be required, this is simply not true. In systems that have lower VOC’s and are unable to sustain an auto thermal condition the supplemental fuel in injected and mixed with the plants VOC’s. As a result the injected additional fuel offers lower Btu value than simply running the fuel through a burner system.

Many times these flameless regenerative thermal oxidizer systems use 50+% more fuel than their counterparts which offer direct burner control. This amount can add to the operational fuel costs thousands of dollars per year, not to mention the lack of natural resource concerns.

Costs

An example of fuel use comparison on a 25,000 SCFM Regenerative Thermal Oxidizer is listed below:

Thermal Destruction Temperature of 1500°F – No VOC Loading: 6,100,000 Btu’s

Thermal Destruction Temperature of 1500°F – Natural Gas Injection No VOC Loading: 10,250,000 Btu’s

With supplementing the VOC’s by means of natural gas you are in fact operating without a flame at typical cost of 50+% greater. In this situation a plant operating a regenerative thermal oxidizer system which has VOC levels of 4400 ppmv stated as methane. The required additional fuel by burner would approximate 1,000,000 Btu’s based on the national average cost would approximate $4.75 per hour. However, using the same evaluation criteria for a natural gas injection or (Flameless) regenerative thermal oxidizer the system; the cost would estimate around $19.00 per hour.

These examples are based on field examinations and are approximate considerations. Over the year operating a natural gas injection or (Flameless) regenerative thermal oxidizer system would cost $14.25 per hour more than its flamed counterpart at an annual cost of over $41,000. Totaling calculations are based on 8 hour days 360 days per year. For more information about reducing regenerative thermal oxidizer operating costs by means of low fuel PLC controlled burners visit: American Environmental Fabrication & Supply, LLC or call +1 918 708-1253.