SoCare-MSI supplies BTG Rotary Concentration Meter and valve

1 item Unit VBW1100-DN100 (FB0104992-HB0101022）

Materials: BTG FB0104992 pulp flow control main mass valve.

Diameter - 100 mm, DIN/ANSI flange-less, ball type, segmental; actuator motor voltage: 230 V

C Control unit HB0101022 VBW-1100 (wall mounted).

2 position Sensor MEK2500

Rotary sensor for measuring BTG FMEK-2500 pulp mass concentration

Stainless steel housing

Flow control: 0.5 liter/min

Impeller: Large

Sensor element: B

Mechanical seal: FPM (standard)

O-ring seal: Viton/Nitrile

Communication protocol: 4-20 mA+HART(R).

Cable length: 10 m

The BTG Rotary Concentration Meter is a classic and widely recognized instrument in the pulp and paper industry for measuring the consistency of pulp slurries.

Here’s a detailed breakdown of what it is, how it works, and its role.

What is a BTG Rotary Concentration Meter?

It is an online, process control instrument that measures the consistency of pulp stock. "Consistency" in this context refers to the weight percentage of oven-dry wood fibers in a pulp-water slurry. It is a critical parameter for controlling the quality and efficiency of papermaking.

While "Rotary Concentration Meter" is the common name, the more technically accurate term is a Rotary Consistency Transmitter (RCT). BTG (now part of the Ecolab group) is a leading manufacturer of these devices.

Key Principle: Shear Force Measurement

The fundamental principle behind the BTG meter is measuring the shear force that a pulp slurry exerts on a sensing element.

· Water is a Newtonian fluid: Its resistance to flow (viscosity) is constant.

· Pulp slurry is a non-Newtonian fluid: Its resistance to flow changes with the applied force. The more fibers present (higher consistency), the greater the resistance or "drag" when you try to move an object through it.

The BTG meter measures this "drag" or shear force directly.

How It Works: Step-by-Step

A BTG Rotary Concentration Meter is typically installed directly in the pulp pipeline. Its operation can be broken down as follows:

1. Sensing Element: The core of the instrument is a rotor (a bladed or slotted cylinder) that is immersed in the flowing pulp slurry.

2. Constant Speed Motor: A motor drives this rotor at a constant, slow speed (e.g., 5-10 RPM).

3. Measuring Drag: As the rotor turns, the fibers in the slurry create a drag force that tries to slow it down. The higher the consistency, the greater the drag force.

4. Reaction Torque: This drag force creates a proportional reaction torque on the sensor's housing or on a stationary measuring element near the rotor.

5. Torque Measurement: A highly sensitive torque sensor measures this reaction force. The instrument does not measure the speed of the rotor; it measures the force required to keep it turning at a constant speed.

6. Signal Output: The measured torque is converted into an electrical signal (e.g., 4-20 mA) that is proportional to the pulp consistency. This signal is sent to the plant's control system (DCS/PLC).

Key Features & Characteristics

· Robust and Proven Technology: This design has been used for decades and is known for its reliability in the harsh environment of a pulp or paper mill.

· Online and Continuous: Provides a real-time measurement, allowing for immediate control of dilution valves or refiners.

· Sensitive to Fiber Type: The calibration is dependent on the type of pulp fiber (e.g., softwood, hardwood, recycled). A meter calibrated for one type will need re-calibration if the fiber type changes significantly.

· Compensations: Modern versions include temperature compensation, as the viscosity of the water phase can change with temperature and affect the reading.

· Installation-Sensitive: Requires a properly sized and installed flow chamber to ensure a full pipe and representative flow across the sensor for an accurate reading.

Common Applications in Pulp & Paper Mills

BTG Rotary Concentration Meters are used throughout the process:

· Pulp Blending: Ensuring the correct consistency of different pulp types before they enter the paper machine.

· Machine Chest Outflow: Controlling the consistency of stock fed to the paper machine.

· Refiner Control: Monitoring and controlling the consistency ahead of refiners, which is critical for proper fiber development.

· Recycled Fiber (RCF) Lines: Measuring consistency in pulpers and cleaner systems.

· Chemical Addition: Accurate consistency measurement is needed for precise chemical dosing (e.g., dyes, additives).

Advantages and Limitations

Advantages 

Direct Measurement: Measures the fundamental fiber property (shear force). 

Robust Design: Handles abrasive slurries well.

Wide Measurement Range: Effective across typical process consistencies (e.g., 1% to 6%). 

Industry Standard: Well-understood technology with extensive support. 

Limitations

Fiber-Specific Calibration: Requires different calibrations for different pulps.

Sensitive to Contaminants: Large debris or "ropes" of fiber can damage the sensor.

Affected by Air Entrainment: Air bubbles in the slurry can cause erratic readings.

Requires Maintenance: Bearings and seals need periodic inspection and replacement.

In essence, the BTG Rotary Concentration Meter is a workhorse instrument that provides a critical measurement for the pulp and paper industry. By measuring the torque required to rotate a sensor at a constant speed through a pulp slurry, it gives a reliable and continuous indication of fiber concentration, which is indispensable for process automation, quality control, and cost savings.

If you are working with one, it's crucial to have it properly calibrated for the specific pulp type and to maintain it according to the manufacturer's guidelines

Pls contact us if you need: info@socaremsi.com

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