Steam boiler systems provide energy to a variety of commercial, institutional, and industrial applications. Properly treated water is necessary for reliable and efficient operation of these systems. Water treatment control ranges for steam boilers can vary based upon the makeup water quality, boiler design, operating pressure, steam requirements, and steam quality/purity needs.
Boiler water quality guidelines are published by a number of industry organizations. These groups often include manufacturers, engineers, scientists, and allied industry representatives. When specifying a treatment program, water treaters often use these singularly or in combination to provide the best recommendations for the conditions at hand. Some commonly referenced guidelines include those from the American Boiler Manufacturer Association (ABMA) and the American Society of Mechanical Engineers (ASME). Individual equipment manufacturers may also publish guidelines for the care and maintenance of their specific equipment.
System water should be tested and monitored at the pretreatment process, feedwater, boiler, and condensate to ensure reliable operation at all stages. Operation outside of control parameters can result in problems that:
The table below summarizes common boiler treatment tests and their importance to the water treatment program.
Establishes boiler blowdown control range and monitors changes in raw water.
Impacts boiler blowdown and can indicate other water quality changes that may influence both pretreatment and boiler operation.
Used to calculate water softener capacity setpoint.
Unexpected changes can result in hardness breakthrough or salt overuse.
May establish boiler blowdown control range, impacts condensate system corrosion, or used to calculate dealkalizer capacity setpoint.
May impact neutralizing amine uses, boiler blowdown rate, or result in dealkalizer alkalinity breakthrough.
May establish boiler blowdown control range.
May form insulating deposits both inside the boiler and within the steam system.
Indicator of proper softener operation.
May cause scale deposit formation in downstream pretreatment equipment and boilers.
May consume treatment chemistry within the boiler.
Indicator of successful softener regeneration rinse cycles.
May impact boiler conductivity and increase blowdown.
Evaluate proper softener regeneration and timings.
Indicator of proper dealkalizer operation.
May impact boiler cycles and lead to increased condensate system corrosion/neutralizing amine chemical usage.
Indicator of successful regeneration rinse cycles.
Evaluate proper regeneration and timings.
Reverse Osmosis (RO)
Establishes boiler blowdown control range.
Ensures proper RO operation.
Impacts boiler blowdown.
Review RO operation.
Ensure proper pretreatment and RO operation.
Causes scale formation and consumes treatment chemistry within the boiler.
Review pretreatment and RO operation.
To monitor RO operation and normalize data.
Impacts RO performance.
Clean RO when indicated by normalized data.
Used for boiler cycle calculations.
Reference value for feedwater quality and monitoring of carryover occurrences.
Impacts boiler cycles.
May lead to scale deposits and corrosion in boiler system if outside range.
Perform condensate survey to find contamination source.
Evaluate pretreatment performance and/or boiler operation.
Indicates pretreatment problems or condensate contamination.
May lead to scale deposits if outside control range.
Check pretreatment operation or perform condensate survey to find hardness source.
Used for corrosion control in feedwater system.
May lead to corrosion if outside control range.
Check chemical feeds and condensate pH.
If high levels are present in raw makeup water, may indicate corrosion in makeup, feedwater, and/or condensate return systems.
Indicator of corrosion and can cause boiler deposits.
Depending upon the system, check:
Used for cycle indicator when present at sufficient concentration.
May be a limiting factor for boiler cycles of concentration.
Can cause boiler deposits.
Check pretreatment equipment and percent condensate return.
Used to monitor blowdown requirements.
Low levels (excessive blowdown) wastes water and treatment chemicals and can cause corrosion.
High levels (inadequate blowdown) can cause scale deposits and/or carryover. Scale deposits can result in boiler failure.
If low, blowdown should be reduced. Note: decreasing the blowdown will increase the chemical levels.
If high, blowdown should be increased or pretreatment should be checked. Note: increasing blowdown will decrease the chemical levels.
May be used to monitor blowdown requirements.
When a limiting factor, used to ensure silica stays within control range.
When used to monitor blowdown, low levels (excessive blowdown) wastes water and treatment chemicals and can cause corrosion.
High levels can cause scale deposits and/or carryover. Scale deposits can result in boiler failure.
Used individually or in combination to determine the ability of the program to absorb hardness leakage.
Provides generalized corrosion protection.
Low levels can allow scale deposits and corrosion to occur.
High levels can cause carryover, corrosion, and deposit formation.
Deposits and corrosion can cause steam system failure.
Tracer/Actives (Phosphate, Polymer, Fluorescein, Molybdenum)
Ensure target inhibitor chemical levels are maintained in boiler.
Low levels can allow scale deposits and corrosion to occur which can lead to steam system failure.
High levels can waste chemicals.
If low, increase feed rate of product. Note: decreasing blowdown may also increase tracer level.
If high, decrease feed rate. Note: increasing blowdown may also decrease tracer level.
Hardness in the feedwater can cause phosphate and alkalinity to drop. Eliminate the source of hardness.
Ensure proper oxygen scavenger residual levels.
Low levels can result in corrosion throughout the boiler system.
If low, increase feed rate of product. Note: decreasing blowdown may also increase sulfite level.
If high, decrease feed rate. Note: increasing blowdown may also decrease sulfite level.
Check deaerator for proper operation (e.g., proper venting, temperature).
May indicate boiler water carryover or condensate contamination.
Contamination may lead to boiler scale deposits.
Low purity steam due to carryover may impact processes using steam (e.g., wet packs or instrument staining)
Confirm and eliminate boiler carryover.
Conduct condensate survey to find source contamination.
Indicator of presence of carbonic acid and neutralizing amine.
Low pH can allow corrosion of the condensate return system.
High pH may indicate neutralizing amine overfeed. Can also result from carryover.
High or low pH may also result from condensate contamination.
If pH is low and iron levels are in range, consider adjusting pH control range lower.
Low pH: Confirm pretreatment operation and/or increase neutralizing amine feed.
High pH: Check for carryover. Reduce neutralizing amine feed if appropriate.
If necessary, perform condensate survey to identify and eliminate contamination source.
Indicator of corrosion.
May cause deposits in boiler.
Corrosion can result in equipment failures and downtime.
If high, confirm:
Indicator of heat exchanger leaks or other process contamination.
Hardness leaks can cause deposits or scale formation in the boiler and consumes chemistry.
Eliminate source of hard water.
Check operation of or install condensate polisher.
*Note: The corrective measures listed are general and may or may not be the best recommendation for your unique system requirements. Always consult with your water treatment professional to determine proper corrective measures.
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