2014 Service Technician Training Program Filtration & Pretreatment Basics Mr. Stephen Lowe, CWT Cascade Water Services, Inc. Boiler System Layout Pretreatment Softeners - Feedwater Boiler Filtration Boiler Raw Water 3 1
Cartridge Housing & Filter Cartridge Filter Housing 5 How a cartridge filter works 2
Cartridge Filters 7 Other examples of cartridge filters Multibag Side Stream Filter Single Bag Filter Feeder Bag Filter Housing 9 3
Bag Filters 10 Media Filtration Units Single Media ( Sand ) Multi Media 4
Cyclonic Filtration Ion Exchange Pretreatment Equipment 14 Softener with Top- Mounted Control Valve Out 15 5
Softener Ion Exchange Resin Figure 2-9 - Page 2-44 16 Softener Ion Exchange Resin Most preferred Fe 3+, Al 3+, Pb 2+, Sr 2+, Ca 2+, Co 2+, Ni 2+, Cu 2+, Zn 2+, Mg 2+, Mn 2+, Ag +, Cs +, Cd +, K +, NH 4+, Na +, H + Least preferred 17 Normal Softener Operation hard water in Ca, Mg soft water out Na 18 6
Four Steps to Softener Regeneration Backwash Brine Draw Slow Rinse Fast Rinse Service 19 Proper Softener Operation Reduces scale-forming potential Reduces treatment chemical requirements Helps maintain cleaner boiler tubes and surfaces 20 Signs of a Poor Softener Regeneration Short run lengths High effluent conductivity or chloride levels Hardness in effluent 21 7
Troubleshooting a Softener Take a composite sample Manually regenerate the unit Check the brine draw Eductor Valve Brine foot valve 22 Resin Cleaning Softener must be regenerated and then taken off line Drain the bed and open to gain access to the resin Add resin cleaner to the bed and refill covering the resin Insert an air lance into the resin bed Pipe or PVC can be used Do not to disturb the support or gravel bed underneath the resin bed Introduce compressed air through the lance to agitate the resin bed. Continue every 30 min for 2-4 hours Refill, backwash until clear, and regenerate the softener tank twice prior to returning to service Reverse Osmosis (RO) 24 8
Reverse Osmosis (RO) 25 Reverse Osmosis (RO) 26 Surveying Reverse Osmosis (RO) Prefilter Pressure differential (ΔP) across RO Conductivity or hardness Flow rate of permeate Normalize Data 27 9
Troubleshooting Reverse Osmosis (gpm) Performance Tracking Data: 2-Stage RO RO Name: Normalized Permeate Flow 1st Stage Pressure Drop (psig) 2nd Stage Pressure Drop (psig) Net Driving Pressure (psig) Salt Recovery Rejection (%) (%) Baseline Data (Enter new baseline data when new membranes are installed.) Net Feed Interstage Permeate Concentrate Feed Permeate Concentrate Permeate Concentrate Driving Salt Rejection Recovery Date Temp (F) Pressure Pressure Pressure Pressure Conductivity Conductivity Conductivity Flow (gpm) Flow (gpm) Presure (%) (%) (psig) (psig) (psig) (psig) (mmhos) (mmhos) (mmhos) (psig) 5/13/11 77 201 185 5 170 40 12 200 4 800 177.1 98.0% 76.9% Tracking Data 1st Stage 2nd Stage Net Feed Interstage Permeate Concentrate Feed Permeate Concentrate Normalized Salt Permeate Concentrate Runtime Recovery Pressure Pressure Driving Date Temp (F) Pressure Pressure Pressure Pressure Conductivity Conductivity Conductivity Permeate Flow Rejection Drop Drop Pressure Flow (gpm) Flow (gpm) (hours) (%) (psig) (psig) (psig) (psig) (mmhos) (mmhos) (mmhos) (gpm) (%) (psig) (psig) (psig) 5/14/11 77 200 185 5 170 40 12 200 4 800 1432 40.1 15 15 176.6 98.0% 76.9% 5/15/11 77 201 186 5 171 41 13 198 4 795 1456 40.9 15 15 177.6 98.0% 75.9% 5/16/11 78 204 189 5.1 173 41 13 204 4.1 806 1480 39.7 15 16 179.9 98.0% 75.9% From AWT Website: Reverse Osmosis Calculation and Survey Workbook 28 Ultrafiltration Ultrafiltration is used as a pre-treatment step in reverse osmosis processes in many Middle Eastern countries to potable drinking water, as there is little fresh water available in those areas. Reference: Wikipedia 29 Boiler System Layout Pretreatment Softeners - Feedwater Feedwater System Boiler Filtration Boiler Raw Water 30 10
Feedwater Tanks and Deaerators Reduce dissolved oxygen levels Remove other gases Chemically remove residual oxygen 31 Importance of Oxygen Removal Oxygen causes severe pitting-type corrosion. Oxygen Pitting in a Standby Boiler Tubercules Covering Oxygen Pits 32 33 11
Chemical Injection Point Spray-type Deaerator 34 What to look for when inspecting a Deaerator Cracks around any weld seam in both the heater and storage sections Cracks in vent line piping water contamination can block proper venting Look for corrosion deposits Look to see that the distribution trays are stacked uniformly If cracks are found document the location for future reference 12