V-cone Flow Meters Overview:

V-cone Flow Meters, also known as inner cone flow meters, V-cones, or conical flow meters, are a novel patent-pending differential pressure flow meter. They share the same basic principle as other types of differential pressure flow meters, which is based on the principle of energy conservation in sealed pipelines. The unique design of the V-cone flow meter expands the flow measurement range and avoids some limitations of traditional differential pressure flow meters, resulting in superior working performance. The V-cone flow meter suspends a conical restriction piece in the center of the pipeline, which obstructs the medium flow and reshapes the velocity profile. The measured mediums include water, steam, air, coke oven gas, and organic gases. Medium conditions can range from very low temperatures to supercritical states. Operating temperature: up to 450°C, pressure: up to 25 MPa, capable of measuring high Reynolds numbers up to 5*10^6, and even lower Reynolds numbers as low as 8*10^3. Full-scale differential pressure signals can range from less than 0.1 kPa to several tens of kPa.

V-cone flow principle:

V-cone Flow Meters are special equipment for TS inspection and MA coal safety certificates, used for mine applications. They are a type of differential pressure flow meter. The principle of differential pressure has been in use for over a century in flow meters designed based on this principle. The principle is based on the conversion of energy within a sealed pipeline, meaning for a stable fluid, the flow rate is proportional to the square root of the velocity of the medium within the pipe. As the medium approaches the cone, its pressure is P1. When it passes through the cone's flow section, the speed increases and the pressure drops to P2. Both P1 and P2 are transmitted to the differential pressure transmitter via the cone flow meter's pressure taps. As the velocity changes, the differential pressure between the two pressure taps of the cone flow meter will increase or decrease.

The V-cone flow meter uses the same calculation formula for flow measurement as other differential pressure flowmeters, but its unique design of the shunt element forces the medium in the pipe center to flow around the cone, offering many advantages compared to other differential pressure flowmeters. We can understand the performance of the cone flow meter by using the ideal velocity curve distribution diagram. The fluid in the pipe is not subjected to any interference or obstruction, which is what we refer to as an ideal flow state. Its velocity distribution is uniform, with the velocity near the pipe wall almost zero, and the velocity at the pipe center is high due to the frictional force of the pipe wall. As the cone is suspended in the center of the pipeline, it directly contacts the high-velocity region of the fluid, forcing the high-velocity fluid near the center to mix with the low-velocity fluid near the pipe wall, thus equalizing the velocity. Therefore, even at low velocities, the cone flow meter can continuously act on the fluid with the velocity at the pipe center to produce an accurate differential pressure.

In reality, flow distribution is often uneven, and any changes on the pipeline can affect the fluid, such as at bends, valves, reducers, expanders, pumps, tees, and so on. The conical flow meter reshapes the upstream velocity distribution curve using a cone, ensuring measurement accuracy even under extremely adverse conditions.

V-cone Flow Characteristics:

Flowmeter Accuracy: ±0.5%, ±1.0%, ±1.5%. System accuracy should be referenced according to the application conditions and the accuracy of the secondary meter.

Repeatability: Better than ±0.1%

Span ratio: Typically 10:1, can be increased if necessary.

Low straight pipe requirements: A straight pipe section of 0~3D before the flowmeter and 0~1D after it is sufficient to ensure measurement accuracy. Experiments have proven that the V-cone flowmeter can approach a single elbow or double elbows at different planes with minimal impact on accuracy.

Long-term Stability: The conical shape design ensures a gradual transition of fluid flow through the cone, without abrupt changes. The β value can remain constant over the long term, allowing the instrument to be used for a long time without recalibration.

Signal Stability: All differential pressure flowmeters will exhibit "signal fluctuation," meaning that even if the fluid is very stable, the signal generated through a throttle element will still fluctuate. For orifice plates, the vortices formed after the throttle element are longer, and these long vortices produce high-amplitude, low-frequency fluctuation signals that can interfere with the readings of the differential pressure gauge. In contrast, cone flowmeters create smaller vortices downstream, resulting in low-amplitude, high-frequency fluctuation signals.

Pressure loss: Small, due to the absence of prominent baffles, the pressure loss of the conical flow meter is 3/4 less than that of the orifice plate.

No dead zones: The conical "blow-off" design eliminates dead zones, ensuring no fluid fragments, sludge, or impurities accumulate on the cone.

Mixing Function: The vortices produced downstream of the V-cone flowmeter are short vortices, which can mix the medium downstream. Therefore, the V-cone flowmeter, while functioning as a flowmeter, can also be used as a static mixer in many applications, quickly and thoroughly mixing the medium evenly.

V-cone flow application:

Medium: Coal gas (including gas with humidity below 5%), various hydrocarbons (including wet HC gases), various rare gases, air (including air containing water, SiO2 particles, and other suspended matter), flue gas, saturated steam (comprising both vapor and water phases), superheated steam, water, etc.

Conditions: From subcritical to supercritical state, temperature up to 450°C, pressure 25 MPa.

Calculations: Each conical flow meter is calculated using specialized software based on the properties, pressure, and temperature of the fluid. Users can select the β value according to their specific application conditions (composition of the medium being measured, temperature, pressure, pipe diameter, normal flow rate, allowable pressure loss).

Maintenance: The conical flow meter is maintenance-free and does not require regular maintenance or calibration.

Application Scope: