Chlorine Emissions for the Sentry Scrubber 2000

The Sentry 2000 is a patented horizontal crossflow packed bed scrubber system with major applications in chlorine and sulfur dioxide emissions control. These systems have been installed for the emergency scrubbing of chlorine and sulfur dioxide container rooms should leakage of the containers or piping systems occur.

The major design criterion applied to scrubber systems is the stack discharge concentration during emergency operation. This concentration is specified by the Uniform Fire Code (UFC) not to exceed one half of the immediately dangerous to life and health (IDLH) level of a toxic gas. From the late 1980’s to 1995 the IDLH level, expressed in parts per million (PPM), had been set at 30 PPM for chlorine. During 1995, however, the chlorine IDLH level was changed to 10 PPM.

In 1993, Powell Fabrication & Manufacturing, Inc. in conjunction with Mr. Ralph Strigle, a world-recognized expert in packed tower scrubber systems, designed the Sentry 2000 to neutralize chlorine and sulfur dioxide. Based on mass transfer efficiency calculations, the Sentry 2000 system utilized packed bed technology developed over more than 50 years. Mass transfer efficiency calculations for packed beds have proven to be accurate when compared to actual systems. Additionally, results for packed beds, unlike spray chambers or venturi scrubbers, can be scaled upwards or downwards reliably. Enclosed is a technical paper by Mr. Strigle presenting the calculations used to predict and corroborate the performance of the Sentry 2000. System performance is verified using two independent methods consisting of mass transfer driving forces with inlet and outlet concentrations.

The Sentry 2000 was designed to operate at an inlet flow rate of 3,000 ACFM for contaminant release rates in excess of 78 lbs/min. This leakage rate is specified by the UFC and represents an overfilled one ton chlorine or sulfur dioxide cylinder emptying in 30 minutes. The design was originally based on the 1993 IDLH of 30 PPM for chlorine and 100 PPM for sulfur dioxide but is easily adaptable to reduced IDLH levels.

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