Ultra-High Performance VOC Destruction Technology for Semiconductor Fabrication Operations

Ultra-High Performance VOC Destruction Technology for Semiconductor Fabrication Operations
David F. Bartz – Alzeta Corp., Frederick E. Moreno – Alzeta Corp. (SSA Journal Volume 6 Number 2 – June 1992 pp. 49 – 55 )

Conventional incineration of volatile organic compounds (VOCs) emitted from semiconductor fabrication processes normally requires high temperature, prolonged residence time, and high levels of turbulence in large, heavy equipment to achieve high destruction removal efficiency (DRE). These conditions also result in high NOx emissions, high fuel usage, large size, slow thermal response (unsuitable for batch operations) and high capital cost. A new, alternate thermal destruction process using porous ceramic radiant burner technology has demonstrated exceptional destruction performance (99.99%) concurrently with 10ppm NOx and CO in a compact, very quick response (2 second) thermal oxidation system. Combustion air, laden with volatile organic vapor is thoroughly mixed with gaseous support fuel prior to combustion. The resulting combustion process in the ceramic matrix brings fuel, air and VOC intimately together accelerating the destructive process. Laboratory and field tests have routinely achieved 99.99 + % DRE with chlorinated and non-chlorinated solvents and gasoline vapors (emissions below detectable limits of 1 part per billion). NOx and CO emissions have also been consistently extremely low. Most recent development and testing has been with inward fired adiabatic burner technology. The VOC-fuel-air mixture flows radially inward and burns on the interior of a radiant porous ceramic cylindrical combustion surface. Advantages over prior designs include:

  1. Ultra high destruction removal efficiencies (99.99%+) simultaneous with less support fuel use because the inward fired burner is inherently radiantly recuperated permitting very high combustion efficiency with much leaner fuel/air mixtures. This level of performance will likely be required as the regulations falling out of Title III of the 1990 Clean Air Act come into effect;
  2. Fast (seconds) on and off and rapid response to changes in stream conditions making the technology suitable for rapidly changing or batch type operations such as semiconductor manufacturing, photolithography processes, printed circuit board manufacturing, and other intermittent processes;
  3. Ultra low NOx and CO (below 10 ppm ref. to 3% oxygen) due to uniform low temperature and stable operation with very lean fuel/air mixtures;
  4. Compact, light weight skid-mounted (and roof-mounted) systems. No large, heavy refractory lined combustion chamber or ceramic fill yielding quicker thermal response, compact and light weight designs and lower cost construction; and
  5. Units can be located near clusters of fab machines and quickly moved when process changes warrant. Modular configuration and quick response eliminate the need for large, costly, continuous operation regenerative incinerators that process the flow of an entire fab facility. Multiple, smaller units located close to groups of fab machines can provide a more flexible, lower cost, higher performance environmental solution with higher levels of availability that are achievable by a single, large system serving an entire plant.

Two full size inward fired incinerator packages have been tested thus far and testing at a semiconductor facility is planned. A field unit was installed in Hayward, California, in August, 1991, to destroy gasoline vapor produced form vacuum extraction. It has operated continuously. The unit was extensively instrumented and was equipped with a data logger to monitor operational and VOC stream trends. The laboratory unit (similar to the field unit) was fully characterized for environmental and operational performance with several organic solvents and vapors (both chlorinated and non-chlorinated). Efforts are now underway to install a prototype unit specifically designed for semiconductor process environmental control and to prepare the technology for commercial introduction. The paper describes the inward-fired adiabatic radiant burner technology and presents the results of laboratory and extensive field testing including DRE performance and emissions data for NOx, CO and hydrocarbons.



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