Understanding Steam System Tests and Critical Parameters

  • 9 January 2024
  • Author: Chem-Aqua, Inc
  • Number of views: 933
  • 0 Comments

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:

  • Increase energy, water, maintenance, and operation costs
  • Damage the steam system
  • Result in system failure

The table below summarizes common boiler treatment tests and their importance to the water treatment program.

Sample

Test

Purpose

Consequences

Corrective Measures*

Raw Water

Conductivity

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.

 

Hardness

Used to calculate water softener capacity setpoint.

Unexpected changes can result in hardness breakthrough or salt overuse.

 

Total Alkalinity

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.

 

Silica

May establish boiler blowdown control range.

May form insulating deposits both inside the boiler and within the steam system.

 

Softener

Hardness

Indicator of proper softener operation.

May cause scale deposit formation in downstream pretreatment equipment and boilers.

May consume treatment chemistry within the boiler.

Confirm:

  • Salt is in brine tank
  • Proper regeneration (e.g., elution study)
  • Softener capacity
  • Hard water not bypassing softener
  • Proper softener operation
  • Proper resin level and condition.

Chlorides

Indicator of successful softener regeneration rinse cycles.

May impact boiler conductivity and increase blowdown.

Evaluate proper softener regeneration and timings.

Conductivity

May establish boiler blowdown control range.

Indicator of successful softener regeneration rinse cycles.

Dealkalizer

Total Alkalinity

Indicator of proper dealkalizer operation.

May impact boiler cycles and lead to increased condensate system corrosion/neutralizing amine chemical usage.

Confirm:

  • Salt is in brine tank
  • Proper regeneration (e.g., elution study)
  • Dealkalizer capacity
  • High alkalinity water not bypassing dealkalizer
  • Proper dealkalizer operation
  • Proper resin level and condition

Chlorides

Indicator of successful regeneration rinse cycles.

May impact boiler conductivity and increase blowdown.

Evaluate proper regeneration and timings.

Conductivity

May establish boiler blowdown control range.

Indicator of successful softener regeneration rinse cycles.

Reverse Osmosis (RO)

Conductivity

Establishes boiler blowdown control range.

Ensures proper RO operation.

Impacts boiler blowdown.

Review RO operation.

Hardness

Ensure proper pretreatment and RO operation.

Causes scale formation and consumes treatment chemistry within the boiler.

Review pretreatment and RO operation.

Temperature/
Pressures/
Flow Rates

To monitor RO operation and normalize data.

Impacts RO performance.

Clean RO when indicated by normalized data.

Feedwater

Conductivity

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.

Hardness

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.

pH

Used for corrosion control in feedwater system.

May lead to corrosion if outside control range.

Check chemical feeds and condensate pH.

Iron

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:

  • Condensate treatment levels
  • Operation of condensate polisher
  • Deaerator operation
  • Oxygen scavenger feed
  • Condensate system for sources of iron contamination
  • Pretreatment iron levels

Silica

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.

 

Boiler Water

Neutralized Conductivity

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.

Silica

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.

Alkalinity/

P-Alkalinity/

M-Alkalinity/

OH-Alkalinity/

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.

Ensure:

  • Target cycles of concentration are maintained (e.g., neutralized conductivity, silica)
  • Proper chemical feed (e.g., alkalinity builder)
  • Soft feedwater
  • Adequate condensate quality (e.g., pH, contamination)

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.

Sulfite

Ensure proper oxygen scavenger residual levels.

Low levels can result in corrosion throughout the boiler system.

High levels can waste chemicals.

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).

Condensate

Conductivity

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.

pH

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.

Iron

Indicator of corrosion.

May cause deposits in boiler.

Corrosion can result in equipment failures and downtime.

If high, confirm:

  • Sample line is thoroughly flushed.
  • pH is within control range.
  • Condensate treatment chemicals properly fed.
  • Deaerator properly removing oxygen.
  • Pretreatment is properly removing alkalinity.
  • Process contamination is eliminated.

Hardness

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. 

Conclusion
Effective water treatment is a critical part of the preventative maintenance program for any steam system. When determining a new water treatment program and critical process parameters, partnering with an experienced solution provider is vital. A customized water treatment program from Chem-Aqua does more than protect steam systems. Tailored treatment solutions help maximize the life, efficiency, reliability, and safety of steam water systems while keeping energy, water, and maintenance costs to a minimum.

To learn more about Chem-Aqua and our superior line of programs, products, and services, visit www.chemaqua.com today.

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