Isn't Rosemount 3051S CD0 the Right Choice for Stable Furnace Negative Pressure Measurement in Power Plants?

Reliable Furnace Negative Pressure Measurement for Thermal Power Plant Boilers

In thermal power plant boiler operation, furnace negative pressure (furnace draft) is one of the most critical safety parameters of the air-flue gas system. The furnace is normally kept under a slight negative pressure of -20 to -300 Pa to prevent high-temperature flue gas leakage, suppress deflagration risks and ensure stable combustion.

Because the pressure range is extremely small, the operation is continuous and the environment is harsh, furnace negative pressure measurement has long faced a number of field difficulties that place extremely high demands on instrumentation.

Key Challenges in Furnace Draft Measurement

• Zero drift caused by long-term high temperature and dust at the furnace tap point
• Tiny pressure signals that are difficult for conventional transmitters to reflect accurately
• Frequent process disturbances that make the negative pressure signal fluctuate noticeably

The Solution: Rosemount 3051S CD0 Micro Differential Pressure Transmitter

The Rosemount™ 3051S CD0 micro differential pressure transmitter, built on the Rosemount 3051S platform with an ultra-stable sensing module and extremely low zero drift, continuously outputs reliable furnace draft signals under high temperature, dusty and long-term continuous operation conditions. Combined with actual field operating conditions, the 3051S CD0 effectively solves the following problems.

Challenge 1: Zero Drift at High-Temperature, Dust-Laden Tap Points

Furnace negative pressure tap points are usually located near the upper part of the furnace or the combustion zone, where they are exposed to high temperature, dust and slight negative pressure for long periods. Under such conditions, ordinary micro differential pressure transmitters are prone to zero drift caused by diaphragm performance degradation and temperature effects. The measured value shifts as a whole and can no longer reflect the actual furnace pressure.

The 3051S CD0 identifies real furnace pressure changes through a dual-capacitance sensing structure and corrects related errors with temperature compensation. It maintains long-term zero stability under high-temperature tap point conditions, ensuring accurate and reliable negative pressure measurement.

Challenge 2: Weak Signals Are Difficult to Detect Accurately

The pressure value at the furnace negative pressure measurement point is very small — typically only tens to hundreds of Pa. Affected by impulse line damping and condensate pot buffering, conventional transmitters respond insensitively to tiny pressure changes at the tap point, making the signal “sluggish” during draft regulation and affecting the control accuracy of combustion and induced draft fans.

In small-range measurement, performance depends not only on sensor accuracy but also on whether low-range signals can be recognized. Instead of simple range compression, the 3051S CD0 adopts a sensing module natively designed for micro differential pressure, improving effective signal utilization at low ranges. High-precision signal processing inside the transmitter ensures that even attenuated micro negative pressure changes are reflected stably and continuously.

Challenge 3: Frequent Disturbances Cause Signal Fluctuation

Process disturbances inside the furnace — combustion fluctuations, coal mill start/stop and load changes — directly affect the pressure state at the negative pressure tap point. Combined with flue gas pulsation in the impulse lines, these disturbances easily cause obvious fluctuation of the negative pressure signal, resulting in unstable DCS displays and frequent adjustments by the automatic control system.

The 3051S CD0 provides digital damping and signal filtering functions. The damping time can be reasonably set according to the actual working conditions at the furnace draft tap point, effectively distinguishing real pressure changes from transient disturbances. As this processing is completed inside the transmitter, the output signal is smoother and more stable, which is highly beneficial for the stable operation of automatic control systems.

Customer Benefits

Furnace negative pressure measurement places high demands on instrument performance and adaptability in engineering applications. By adopting the Rosemount 3051S CD0, power plants can significantly improve the stability and controllability of negative pressure measurement, contributing to better boiler combustion control and the safe, stable operation of the entire unit.