Dual Safety Barriers for Boiler Steam Drum Level Measurement: Jiwei JWrada® Radar and Ring-11 Vibrating Level Switch

In modern large-scale thermal power generation, petrochemicals, and biomass power sectors, the Boiler Steam Drum is recognized as one of the most critical measurement points for safety throughout the entire process. As a core component of the utility boiler, the steam drum is not only responsible for saturated gas separation but also undertakes the vital tasks of water storage and thermal balance regulation.

Under extreme conditions with temperatures up to 400 °C, achieving precise control of the Water Level and redundant alarming for High and Low Water Levels directly impacts the service life of the unit and the safety of personnel.

This article explores a “Software-Hardware Dual-Control” solution combining the Jiwei JWrada® 80GHz high-frequency radar level transmitter and the Ring-11 high-temperature/high-pressure vibrating level switch, based on a successful application in a 660MW unit utility boiler by Jiwei Automation.

I. Steam Drum Level Monitoring: The “Lifeline” of Power Plants

The steam drum level is the most critical parameter in boiler operation.

• High Water Level (Flooding): Saturated steam carries water into the superheater, reducing heat exchange efficiency and potentially causing water hammer damage to turbine blades, leading to catastrophic accidents.
• Low Water Level (Dry-out): The boiler water circulation is disrupted, causing heat exchange tube walls to overheat and burst due to dry firing, resulting in an emergency boiler shutdown.

However, under high-pressure conditions, the physical properties of water molecules undergo significant changes, presenting massive challenges for traditional measurement technologies like differential pressure or electrical contact types:

1. Density Fluctuations: As pressure rises, the density of saturated steam and saturated water converge, leading to significant errors in differential pressure measurements.
2. Gas Phase Interference: The steam drum is filled with high-density, high-velocity saturated steam, which easily absorbs or scatters microwave and ultrasonic signals.
3. Stringent Requirements: The application requires not only continuous measurement but also independent hardware limit interlocking protection.

II. Continuous Measurement Solution: JWrada® 80GHz Radar “Piercing the Steam”

To address the complex saturated steam environment inside the drum, the JWrada® PRO high-frequency radar level transmitter provides a performance advantage that sets it apart.

1. 80GHz Millimeter Wave: Ultimate Focusing Capability

In narrow bypass pipes or pre-installed nozzles, the JWrada® PRO features a beam angle of only 3°, ensuring highly concentrated microwave energy. It acts like a scalpel, bypassing wall scaling or internal components to directly capture the reflection signal from the gas-liquid interface, achieving measurement accuracy of ±1mm.

2. Cloud-Based Remote Collaboration: Proprietary Software Debugging

A core competitiveness of the Jiwei JWrada® is its self-developed cloud-based remote commissioning system. In the early stages of a power plant commissioning, surging pressure caused the dielectric constant (εr) of the medium to fluctuate non-linearly, resulting in cluttered echo signals. Jiwei engineers, without entering the high-risk site, remotely accessed the device’s Echo Curve and EFT (Interference Suppression Curve) via a cloud server.

The engineers optimized the “Steam Compensation Coefficient” and Dynamic Gain online, using software algorithms to precisely filter out high-pressure gas phase interference. This “Cloud Diagnosis” capability is currently unmatched by most domestic competitors, significantly improving startup efficiency.

III. Limit Interlock Solution: The “Iron Body” of Ring-11 Vibrating Switch

If the radar is the “eye,” then the Ring-11 High-Temperature and High-Pressure Vibrating Level Switch is the ultimate “circuit breaker” for steam drum safety.

1. Resilience to Extreme Conditions

The 400 °C temperature inside the steam drum is a nightmare for most electronic components. The Ring-11 is specifically designed for such extremes. Its fork is made of high-temperature resistant alloys and utilizes complex full-welding sealing processes to withstand static pressures, ensuring the fork’s frequency remains stable under high heat and pressure.

2. Anti-False Alarm: Immune to Buildup and Bubbles

Boiler water often contains chemicals or impurities that produce foam. The Ring-11 uses a frequency-shift detection technology. It only responds to the liquid phase it touches and remains immune to interference from saturated steam or material buildup. This characteristic ensures absolute reliability for high/low water alarms, eliminating unplanned shutdowns caused by false alarms.

IV. Real-World Case Study: 660MW Unit Utility Boiler Project

Project Background:

A large thermal power plant in Central China experienced frequent false alarms from original electrical contact level gauges under high pressure. Moreover, aging ceramic seals led to steam leakage, seriously threatening production safety.

Solution:

The plant introduced the Jiwei JWrada® radar level transmitter for primary continuous level monitoring and installed four Ring-11 vibrating level switches on both sides of the steam drum as interlocking protection for High-High and Low-Low water levels.

Application Results:

1. Commissioning: The radar was installed directly on top of the existing bypass pipe. Via the cloud platform, engineers completed the suppression of fixed interference at the bottom of the 3-meter pipe in just 15 minutes, with echo quality (Quality) stabilized above 80dB.
2. Safety Guard: During a transient high-water event caused by a feed pump failure, the Ring-11 accurately captured the moment the level reached the warning line, immediately triggering the protection system for emergency blowdown and successfully preventing a flooding accident.

V. Customer Benefits: More Than Just Reliability

1. Efficiency and Cost Reduction: The non-contact and long-life design of the JWrada® and Ring-11 reduces the annual teardown and seal replacement costs associated with traditional instruments.
2. Simplified O&M: Unique software advantages (fault code viewing, one-key parameter backup) allow plant personnel to monitor all instrument statuses via mobile or cloud platforms.
3. Data Transparency: Real-time echo curves and EFT analysis turn “invisible” internal drum levels into visible, analyzable data streams, supporting the plant’s digital transformation.

VI. Conclusion

Steam drum level measurement is a marathon of precision and safety. Jiwei Automation provides a closed-loop safety solution through the intelligent measurement of the JWrada® radar and the robust protection of the Ring-11 switch. Backed by the advantages of domestic replacement, self-developed software, and remote cloud O&M, Jiwei is guarding the heart of industrial production with greater strength and technical sophistication.