Pollution Prevention and Control Technologies for Plating
Section 3 - Chemical Recovery
3.2 ATMOSPHERIC EVAPORATORS
3.2.2 Development and Commercialization
Atmospheric evaporators are essentially adjuncts to plating tank
evaporation. They increase the head room in the plating tank,
thereby increasing the quantity of rinse water/drag-out that can
be recovered using recovery rinsing. The use of recovery rinsing
in the plating industry was documented more than 50 years ago.
The use of evaporators for chemical recovery extends back more
than 40 years (see reference list in ref. 1). Most of the early
evaporators used by the plating industry were the vacuum type,
which was basically a technology transfer from the chemical processing
industry. These were large units, often with capacities of 400
to 600 gph (1,500 to 2,300 l/hr). Large units were used because
water conservation and pollution control were less important at
that time, resulting in higher flow rates. Also, energy was much
less expensive at that time and therefore there was less incentive
to minimize flows prior to evaporation. In 1974, with the advent
of rapidly rising energy costs, there began a movement to down-size
recovery systems (ref. 300).
Coupled with the Federal pollution control standards, first promulgated
in 1979, plating shops turned to the small and inexpensive atmospheric
evaporators for chemical recovery. Based on the results of the
Users Survey, it is apparent that purchases of this technology
have continued into the 1990's.
There are approximately 25 companies that manufacture evaporative
recovery equipment applicable to the plating industry. This includes
vacuum and atmospheric evaporators for both chemical recovery
and waste concentration (ref. 421). The firms most often mentioned
in the Users Survey were Poly Products Corporation, Techmatic
Inc. and NAPCO.
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