The throttling device flowmeter is a flow measurement instrument based on the differential pressure principle. The flow rate is calculated by the pressure difference generated when the fluid flows through the throttling device. Its core components include the throttling device (primary device) and the differential pressure measurement system (secondary device), which are widely used in the field of industrial process control.

1. Working principle

1. Bernoulli equation and continuity law

When the fluid flows through the throttling device (such as orifice plate, nozzle, venturi tube), the flow cross section shrinks, resulting in an increase in flow velocity and a decrease in static pressure, forming a stable pressure difference (ΔP) before and after the throttling device. The pressure difference is proportional to the square of the fluid flow rate, and the flow rate can be calculated by measuring ΔP.

Formula expression:

$$ Q = K sqrt{rac{Delta P}{ ho}} $$

Where ( Q ) is the flow rate, ( K ) is the instrument coefficient, and ( ho ) is the fluid density.

2. Standardized design basis

The design follows international standards (ISO 5167) and national standards (GB 2624) to ensure that the specified accuracy (±0.5%~±1.0%) can be achieved without actual flow calibration.

2. Main types and features

3. Core technology advantages

1. Structural reliability

No moving parts, high temperature resistance (-50℃~850℃), high pressure (≤40MPa), optional materials such as stainless steel, Hastelloy, etc., with a service life of more than 10 years.

2. Wide adaptability

Supports gas, liquid, steam and partially mixed phase flow (such as gas-liquid mixture), with a wide range of Reynolds numbers (10⁴~10⁷).

3. Economical

Low manufacturing cost, maintenance only requires regular cleaning of pressure ports or calibration of differential pressure transmitters.

4. Typical application scenarios

1. Energy industry

- Steam metering: power plant boiler steam flow monitoring (orifice plate/nozzle)

- Natural gas trade settlement: high-pressure pipeline metering (V cone/Venturi)

2. Process industry

- Chemical reaction feed control: Balanced flowmeter optimizes ratio accuracy

- Metallurgical blast furnace gas: Wedge flowmeter resists dust clogging

3. Environmental protection field

- Sewage treatment: Corrosion-resistant throttling parts measure solid-containing fluids

5. Selection and installation points

1. Key parameters for selection

- Medium characteristics: density, viscosity, corrosiveness (determine the material)

- Working conditions: temperature, pressure, flow range (range ratio 10:1 is appropriate)

- Pipeline layout: straight pipe length (standard orifice plate requires 10D in front and 5D in back, V cone only requires 3D in front)

2. Installation specifications

- Pressure port orientation: gas takes the upper part, liquid takes the side, steam needs to add condensate tank

- Sealing requirements: Flange bolts are tightened three times according to ASME PCC1 standard

- Fluid state: ensure full pipe, single-phase flow, avoid bubbles or precipitation

Throttling device flowmeters are still the mainstream choice for industrial flow measurement due to their mature technical system and economy. When selecting, it is necessary to comprehensively consider the medium characteristics and working conditions, combine new throttling parts (such as V-cone, balanced type) to optimize performance, and strictly follow the installation specifications to ensure accuracy. The technical system of the flowmeter, the choice of flow measurement. When selecting, it is necessary to consider the medium working conditions, optimize the new parts (cone,) and install the specification accuracy