Treatment of Vapors from In Situ Thermal Remediation: Selecting the Best Option and Operating it Properly(PPT)

摘要

In situ thermal remediation (ISTR) technologies are frequently used for treatment of highly contaminated source zones including sites with light and dense nonaqueous-phase liquids (LNAPL/DNAPL). Since thermal treatment often results in removal of tens or hundreds of thousands of pounds of chemicals from the subsurface in a period of several months, vapor treatment systems must be designed to handle dynamic process conditions including elevated temperatures, substantial moisture content, high contaminant mass loading and often acidic conditions. In addition, vapor treatment systems must be robust, providing reliable operational up-time because, unlike conventional “cold” vapor extraction systems, a hot ISTR site will continue to generate steam and contaminant-laden vapors even if the extraction system shuts down. An improperly or inadequately designed or operated vapor treatment system can cause schedule delays, cost over-runs and the potential release of uncontrolled fugitive emissions. Included is a discussion of lessons learned and means and methods to improve reliability of ISTR vapor treatment systems at both the design and field-operational stage. Knowledge and consideration of these critical design and operational parameters is important not only for thermal remediation contractors, but also for regulators, consultants and other remediation practitioners who may design, specify, evaluate or select contractors or vapor treatment systems for ISTR projects.