Key testing parameters for boiler feed water primarily include hardness, dissolved oxygen, pH, silica, sodium ions, etc., which must strictly comply with the national standard GB/T 1576-2018. Deploying online water quality analyzers for real-time monitoring is a critical measure to prevent scaling and corrosion, ensuring safe, economical, and long-term operation of the boiler.
The boiler is the "heart" of many industrial plants, and the feed water is the "blood" that keeps this heart healthy. Untreated feed water, like blood with impurities, causes continuous damage to the boiler—scaling, corrosion, carryover—ultimately leading to soaring energy consumption, unplanned shutdowns, and even safety incidents. Do you truly understand the quality of every drop of water entering your boiler?
During operation, water in the boiler continuously evaporates and concentrates, meaning even trace impurities in the feed water are amplified infinitely. The hazards mainly manifest in three aspects:
1. Scaling Risk: Calcium and magnesium ions (i.e., hardness) in water form hard scale on heat transfer surfaces under high temperature. The thermal conductivity of scale is only 1/30 to 1/50 that of boiler steel. Research indicates that a 1 mm scale layer on heat transfer surfaces increases fuel consumption by 5% to 8%. This not only causes significant energy waste but also leads to local overheating, bulging, and even tube failure.
2. Corrosion Risk: Dissolved oxygen is the most active corrosive agent in boiler systems, corroding economizers, feedwater pipelines, and steam drums. Simultaneously, low pH (acidic conditions) also accelerates corrosion. Corrosion thins metal walls, leading to leaks, tube failures, and reduced equipment lifespan.
3. Steam Quality Deterioration Risk: In medium and high-pressure boilers, silicates and sodium salts from the feed water can be carried over by steam into the turbine, forming insoluble silicate or salt deposits on blades, severely reducing turbine output and efficiency.
Therefore, strict control of feed water quality is the most cost-effective method to manage these risks at the source.
According to the national standard "Water Quality for Industrial Boilers" (GB/T 1576-2018), the key parameters and control requirements for boiler feed water (typically referring to softened water, demineralized water) are shown in the table below. This standard is the authoritative basis for boiler water treatment design and operation.
| Parameter | Significance of Control | Typical Control Target (e.g., Medium-Pressure Boiler) | Primary Hazard |
Hardness | The primary parameter for scaling prevention, refers to the total concentration of calcium and magnesium ions. | ≈0 mmol/L (Approaching zero) | Scaling, Fuel Waste, Overheating/Tube Failure |
Dissolved Oxygen | Key parameter for preventing oxygen corrosion, especially for boilers with heat recovery. | ≤0.1 mg/L (After deaeration) | System Corrosion, Pitting Perforation |
pH Value | Indicates acidity/alkalinity; prevents acid corrosion. | 8.5 – 9.5 (Note for systems with copper alloys) | Acidic Corrosion, Hydrogen Damage |
Conductivity | Indirectly reflects the total dissolved solids (TDS), monitors ion exchange resin exhaustion. | <10 μS/cm (For demineralized water) | Scaling, Carryover |
Silica (SiO₂) | Prevents formation of silicate scales in the turbine. | Strict requirements based on boiler pressure | Turbine Scaling, Efficiency Loss |
Sodium Ion (Na⁺) | Monitors cation exchange resin leakage and contamination. | <100 μg/L (For demineralized water) | Superheater Salt Deposits |
Pro Tip: For power station boilers using demineralized water, Cation Conductivity is an extremely important derived parameter. Measured after passing the sample through a cation exchange column, it eliminates the effect of additives like ammonia, providing a purer reflection of harmful anion concentrations (like Cl⁻, SO₄²⁻), making it a sensitive indicator for detecting water quality abnormalities.
Offline sampling and analysis have inherent lag and cannot capture instantaneous changes in water quality. Implementing a Boiler Feed Water Online Monitoring System is like installing "24/7 sentinels" for the boiler. Its core value lies in:
Real-time Alarming: Immediate alerts if parameters like hardness or dissolved oxygen exceed limits, prompting operators to check softeners, deaerators, etc., preventing unsuitable water from entering the boiler.
Guiding Regeneration/Maintenance: Online conductivity or sodium analyzers can accurately determine ion exchange resin exhaustion, guiding timely regeneration, avoiding waste or water quality breakthrough associated with time-based regeneration.
Data Tracing & Optimization: Continuous historical data recording helps analyze water quality trends, providing a basis for optimizing water treatment processes and reducing chemical consumption.
Reducing Labor Costs & Errors: Automated monitoring reduces frequent manual sampling and testing, minimizing human error.
A complete boiler feed water online monitoring solution typically includes the following core online analyzers:
1. Online Hardness Analyzer:
Location:Outlet of the water softener.
Role:Ensures softened water hardness is absolutely within limits; the final barrier against scaling.
2. Online Dissolved Oxygen Analyzer:
Location: Deaerator outlet, feedwater pump inlet.
Role: Monitors deaeration effectiveness in real-time to prevent oxygen corrosion. Luminescent/optical sensors are a good choice for low maintenance.
3. Online pH & Conductivity Analyzers:
Location: Demineralized water product point, feedwater tank outlet.
Role: pH monitoring controls ammonia dosing for pH adjustment; conductivity monitors the purity of demineralized water.
4. Online Silica / Sodium Analyzer (for High-Pressure Boilers):
Location: Outlet of polishing demineralization (if applicable).
Role: Provides trace-level monitoring of silica and sodium ions, meeting the stringent requirements of power station boilers.
When selecting instruments, focus on their measurement accuracy, long-term stability, anti-interference capability, and ease of maintenance.
Background: A chemical plant operated a 35 t/h steam boiler. The softened water system used a sodium ion exchanger. Previously, they relied on manual sampling and titration once per shift for hardness checks.
Problem: During a night shift, the internal distributor of an ion exchanger suffered minor damage, leading to resin loss and reduced softening efficiency. Within the interval between manual samples, a significant amount of hard water entered the boiler.
Solution: The plant installed Yinrun Environmental's Online Hardness Analyzer on the softened water outlet pipeline, with set alarm limits. Just two weeks later, the system triggered a hardness exceedance alarm in the early morning. The operator on duty promptly inspected and identified the exchanger abnormality, immediately switched to the standby unit, and initiated repairs.
Result: Successfully prevented approximately 50 tons of hard water from entering the boiler, averting a potential scaling incident and unplanned shutdown. Estimated savings in cleaning costs and production losses exceeded 200,000 RMB. The plant subsequently deployed a more comprehensive Yinrun Boiler Water Online Monitoring System at key points.
Facing complex operating conditions and strict standards, an integrated, intelligent monitoring solution is crucial. The Yinrun Environmental Boiler Water Online Monitoring System is designed for industrial applications and offers the following advantages:
Accuracy and Reliability: Core sensors employ mature technologies, ensuring accurate measurements and high stability for long-term reliable operation in industrial environments.
Integrated Design: Allows flexible configuration of monitoring units for hardness, dissolved oxygen, pH, conductivity, silica, sodium, etc., forming a unified solution that simplifies installation and maintenance.
Smart Connectivity: Equipped with a color touchscreen, supports 4-20mA / RS485 Modbus outputs, enabling easy integration into DCS or plant monitoring systems for remote monitoring and data analysis.
Professional Support: Provides full-process services from solution design and installation/commissioning to technical training, ensuring the system functions effectively.
Actionable Advice: Evaluate whether your current method of monitoring boiler feed water has blind spots or delays. Consider introducing online monitoring technology to shift from reactive response to proactive prevention.
Quality control of boiler feed water is the cornerstone of safe and economical boiler operation. Investing in a reliable online water quality monitoring system is not merely about purchasing equipment; it is a significant upgrade to your enterprise's operational safety, energy efficiency, and sustainable development capabilities. It helps you eliminate hazards at the source, making boiler operation more secure and efficient.
Take Action Now: If you wish to learn more about boiler water treatment monitoring technologies or obtain a customized solution, please feel free to contact our professional technical team for a free consultation.
