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
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