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2014 Service Technician Training Program

Filtration & Pretreatment Basics

Mr. Stephen Lowe, CWT – Cascade Water Services, Inc.

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Feedwater

Boiler

Boiler

Softeners

Pretreatment

-

Boiler System Layout

-

Filtration

Raw Water

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Cartridge Housing & Filter

Cartridge Filter Housing

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How a cartridge filter works

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Cartridge Filters

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Other examples of cartridge filters

Multibag Side Stream Filter Single Bag Filter Feeder

Bag Filter Housing

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Bag Filters

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Media Filtration Units

Single Media ( Sand ) Multi Media

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Cyclonic Filtration

Ion Exchange Pretreatment Equipment

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Out Softener with Top-Mounted Control Valve

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Figure 2-9 - Page 2-44

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Softener Ion Exchange Resin

Softener Ion Exchange Resin

Most preferred→ Fe3+, Al3+, Pb2+, Sr2+, Ca2+ ,

Co2+, Ni2+, Cu2+, Zn2+, Mg2+, Mn2+ , Ag+,

Cs+, Cd+, K+, NH4+, Na+, H+ ←Least preferred

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Normal Softener Operation

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Ca, Mg

Na

hard water in

soft water out

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Four Steps to Softener Regeneration

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Backwash

Brine Draw

Slow Rinse

Fast Rinse

Service

Proper Softener Operation

• Reduces scale-forming potential

• Reduces treatment chemical requirements

• Helps maintain cleaner boiler tubes and surfaces

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Signs of a Poor Softener Regeneration

• Short run lengths

• High effluent conductivity or chloride levels

• Hardness in effluent

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Troubleshooting a Softener

• Take a composite sample

• Manually regenerate the unit

• Check the brine draw

• Eductor Valve

• Brine foot valve

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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)

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Reverse Osmosis (RO)

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Reverse Osmosis (RO)

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Surveying Reverse Osmosis (RO)

• Prefilter

• Pressure differential (ΔP) across RO

• Conductivity or hardness

• Flow rate of permeate

• Normalize Data

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Troubleshooting Reverse Osmosis

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Performance Tracking Data: 2-Stage RO RO Name:

Baseline Data (Enter new baseline data when new membranes are installed.)

Date Temp (F) Feed

Pressure (psig)

Interstage Pressure

(psig)

Permeate Pressure

(psig)

Concentrate Pressure

(psig)

Permeate Flow (gpm)

Concentrate Flow (gpm)

Feed Conductivity

(mmhos)

Permeate Conductivity

(mmhos)

Concentrate Conductivity

(mmhos)

Net Driving Presure (psig)

Salt Rejection (%)

Recovery (%)

5/13/11 77 201 185 5 170 40 12 200 4 800 177.1 98.0% 76.9%

Tracking Data

Date Temp (F) Feed

Pressure (psig)

Interstage Pressure

(psig)

Permeate Pressure

(psig)

Concentrate Pressure

(psig)

Permeate Flow (gpm)

Concentrate Flow (gpm)

Feed Conductivity

(mmhos)

Permeate Conductivity

(mmhos)

Concentrate Conductivity

(mmhos)

Runtime (hours)

Normalized Permeate Flow

(gpm)

1st Stage Pressure

Drop (psig)

2nd Stage Pressure

Drop (psig)

Net Driving

Pressure (psig)

Salt Rejection

(%)

Recovery (%)

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

Normalized Permeate Flow

(gpm)

1st Stage Pressure

Drop (psig)

2nd Stage Pressure

Drop (psig)

Net Driving

Pressure (psig)

Salt Rejection

(%)

Recovery

(%)

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.

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Reference: Wikipedia

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Feedwater

Boiler

Boiler

Softeners

Pretreatment

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Boiler System Layout

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Filtration

Raw Water

Feedwater System

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Feedwater Tanks and Deaerators

• Reduce dissolved oxygen levels

• Remove other gases

• Chemically remove residual oxygen

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Importance of Oxygen Removal

Oxygen causes severe pitting-type corrosion.

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Oxygen Pitting in a Standby Boiler

Tubercules Covering Oxygen Pits

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Chemical Injection Point Spray-type Deaerator

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