Cooling Tower Water Treatment During Refinery Turnaround uses Bag Filters and Sand Filters

A Gulf Coast refinery requested Rain for Rent's assistance with a cooling tower cleaning project scheduled during a turnaround. 

After assessing the situation, Rain for Rent recommended a water filtration system consisting of a 48-2 sand media filter, Spillguard™ portable spill containment berm and a dewatering box to capture the backwash from the sand media system.  A diffuser made of Schedule 80 PVC  pipe with 1-inch holes in a single line down the length of the pipe was used to spray the discharge evenly into a solids/liquid separating dewatering box. 

The system worked beautifully during cooling tower recirculation, achieving the necessary water clarity.  However, after bringing one of the production units back on line, a significant quantity of insoluble iron was stirred up and circulated throughout the system.  Suddenly the sand media was unable to reduce the NTU to an acceptable level. 

The Rain for Rent, Baton Rouge team and regional filtration specialist ran a series of vacuum filtration tests on samples captured from the inlet line.  With the plant representatives observing, Rain for Rent determined that the particle sizes contained within the additional circulation volume were in the 1-3 micron range.  These particles were being transported through the sand media bed because the filtration capability was limited to capturing 20-micron particles and larger. 

A PF-400 particulate filter with 1 micron media was added to the system to polish the sand media effluent and reduce the NTUs to an acceptable level.  This method was chosen over a biopolymer flocculant as the plant did not want to introduce any polymers into the cooling tower system. 

The Rain for Rent filtration system effectively cleaned the cooling tower during the turnaround period and led to another filtration job at the site.