The proper treatment of condensate water with activated carbon is a unique challenge, requiring a product that achieves high removal of hydrocarbons while leaching little silica into the condensate stream. Jacobi Carbons has answered this challenge with our newest product, PetroSorb™ HS-D.
Within the petrochemicals and power generation industries it is common practice to recycle condensed steam for use as boiler feed water. Such processes improve plant economics offering a ready source of “pure” heated water ( >80oC) that may not require further demineralization by Ion Exchange systems (IEx). Recycling of the condensate also avoids environmental issues associated with the disposal of water.
However, condensate feed waters frequently contain entrained hydrocarbons from process equipment (e.g. leaking seals on pumps etc.,) or associated hydrocarbon process streams. These hydrocarbons must be removed from boiler feed waters to avoid coking in boiler tubes that reduces heat transfer and boiler efficiency.
Hydrocarbon concentrations may be in excess of 6 mgL-1 but are more typically 2 to 4 mgL-1; and at these concentrations activated carbon is an extremely efficient adsorption media, frequently achieving >95% removal.
Removal of this hydrocarbon contamination with standard activated carbon requires addition of a downstream demineralization IEx system to prevent trace quantities of minerals leached from the activated carbon entering the condensate return loop. A complication with this process is that silicon is also leached from the carbon. This is detrimental to both high-pressure boilers & turbines and ion exchange systems. Deposition of silica in boiler tubes creates scaling heat transfer problems similar to coking and deposition upon rotary vanes of turbines can be catastrophic. Additionally due to its weak ionic charge silica deposited on the beads of IEx systems cannot be removed with normal regeneration cycles and requires use of a specific caustic backwash cycle.
Initially,
bituminous coal based and peat based activated carbons were used in condensate treatment applications. However, both these products are derived from non-renewable resources and their leachable silica content is unacceptably high. In recent years, renewable resource based acid washed coconut activated carbons have been developed offering reduced silica leach properties. However, even these may release silica in the ppm range, a level too great for the application.
In response to this challenge, Jacobi developed PetroSorb HS-D, a specialty washed product with the lowest silica leach properties of any product on the market today. Leach studies on this product have shown lower silica levels after fewer bed volumes of water than other commercially available carbons.
To review the design and operational considerations for using activated carbon as a pretreatment to ion exchange in condensate water treatment, and discuss the silica leach characteristics of various commercially available carbons for this service, please utilize our contact us form to request additional information.
Click the button below to download a Jacobi Technical Bulletin for more information on Condensate Water Treatment.
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