Problem
A large consulting and contracting firm owns and operates
several ex-situ Thermal Desorption Units (TDUs). Each single-load
Thermal Desorption Unit has the capacity of desorbing 15 tons of
soil per hour at a temperature of 400°F - 900°F. These Thermal
Desorber Units have been designed to operate on both chlorinated
and non-chlorinated RCRA, CERCLA, and private industry sites. Since
each TDU has the flexibility to operate on hydrocarbon and
halohydrocarbon sites, the selected pollution control system had to
share this flexibility. Also, due to varying environmental
regulations throughout the country, as they relate to HCL discharge
limits, the selected pollution control system had to eliminate any
HCL generated through oxidation of chlorinated compounds. Finally,
the controls systems portability was a crucial factor since this
contractor's profitability is based upon how quickly the system is
mobilized, the site is remediated, and the unit is demobilized for
movement to the next site.
ACTION
The lack of inexpensive natural gas feeds at many sites, and
therefore the required propane fuel source, lead the customer to
believe that the 1600°F - 2000°F operational temperature of a
thermal incinerator would lead to unacceptable fuel costs. After
examining various equipment capital and operational costs, this
consultant/contractor recognized the benefits of a Chlorinated
Catalytic Oxidizer (Chloro-CatTM) coupled with an HCL
Scrubber. After a thorough technical evaluation and bid process,
GLOBAL TECHNOLOGIES was selected to solve their VOC problem by
providing a mobile treatment package.
SOLUTION
Global's experience in the chlorinated catalytic oxidation and
HCL treatment prior to the initiation of this project was
extensive. At this point, Global had installed over 30 such systems
to treat chlorinated streams from Soil Vapor Extraction (SVE) and
airstripper sites. This experience proved invaluable in designing
and implementing the proper solution. Each rotary kiln TDU could be
expected to exhaust up to 5,000 SCFM of desorption air at a
temperature between 400°F - 900°F and a chlorinated VOC
concentration of 3,000 ppmv. Utilization of a high temperature
baghouse on the TDU skid removed concerns associated with dust or
dirt plugging of the monolithic catalyst cells.
Global utilized an induced draft FRP fan on the backend of the
treatment package due to the high temperature, highly saturated
exhaust from the TDU. As with all Global chlorinated catalytic
systems, a 316L stainless steel shell and tube heat exchanger was
installed in the 316L stainless steel reactor. The chlorinated
catalytic system was designed to provide 99% destruction efficiency
at a temperature of 500°F - 850°F to reduce auxiliary fuel usage.
Safety systems were installed to ensure no HCL condensation or
system corrosion.
The 50' drop deck trailer, upon which the chlorinated system was
mounted, also incorporated a Liquid Propane Vaporizer, a storage
area for equipment transport, and an HCL Scrubber capable of 99.9%
HCL removal in both caustic and pure water mode.
The most recent compliance testing of this turnkey package
demonstrated over 99% destruction of all compounds. The result is
another satisfied Global client.