Concentric Tube Heat Exchangers are often used to maintain heat in the anaerobic digesters. Sludge from the digester is circulated through the inside tubes of the heat exchanger while hot water is passed through the surrounding outer tube as illustrated below. Heat exchangers are also designed to warm incoming sludge before it is transferred into the digester. Another application may be for cooling sludge from thermophilic biological processes.
- Counter-flow or concurrent flow designs are available.
- Full inner tube pipe diameter return bends prevent clogging, reduce head loss, and are fast and easy to remove for service procedures.
- Steel or stainless steel concentric tube designs are available.
- Galvanized steel or stainless steel insulated panel enclosures are available and have quick release and re-set latches used for panel removal and easy access to the heat exchanger tubes.
- Standard designs allow cleaning of the inner tubes without removing them from outer tube or the heat exchanger frame.
- Where restricted access to the heat exchanger installation point within operations buildings, (perhaps at lower levels in these buildings), OTI can design the heat exchanger in small modules that will fit through these restriction points. The modules are then assembled, anchored, and connected to plant piping to complete the installation.