Vortex Flowmeter (Transmitter) EF73

Steam is the heat source most commonly used at production sites. It is an extremely manageable type of energy, offering characteristics such as the ability for high temperature heating and the ability to recover heat through the recovery of condensate.

However, because steam is such a familiar heat source, its cost management tends to be neglected. The cost of steam should be managed in the same way as the cost of electricity, gas and raw materials is managed.

In order to manage and reduce the cost of steam, the first step is to find out the status of the plant. This is done by using a flowmeter installed on each production management unit to take an accurate measurement of the current amount of steam being used.

Features and Benefits

• Using the integrated temperature sensor for the correction, the compact single-unit transmitter calculates and displays the compensated mass flow for saturated steam.
• Capable of simultaneous analog (e.g. instantaneous flow) and pulse (e.g. mass flow) output
• Simple construction has no moving parts and is extremely durable
• Low pressure drop through body
• All sizes of wafer-type (flangeless) share a common face-to-face size

Typical applications

• Measurement of steam flow rates in steam piping and processes
• Measurement of condensate recovery rates
• Measurement of boiler feed water rates
• Do not use for toxic, flammable or otherwise hazardous fluids.

Connection Example

Saturated Steam

The compact single-unit transmitter calculates and displays the compensated mass flow for saturated steam, even when the pressure fluctuates.

If the flowmeter display is difficult to see due to the main body being installed in an overhead or remote location, the remote version can be used for distances up to 30 m.

 

Fluids for Which Both Temperature and Pressure Fluctuate (e.g. Air, Superheated Steam)

Combine a pressure transmitter with the EC351 flow computer to calculate the real-time compensation for superheated steam and air measurements even when pressure fluctuates.

 

Wide Measurement Range for High Precision Measurement

Wide rangeability yields the ability to perform highly accurate measurements even on processes and equipment with large fluctuations in flow rate.

Integrated DSC (Differential Switched Capacitance) Sensor and Temperature Sensor for Mass Flow Compensation

Vortices are detected using a balancing capacitance-type DSC sensor. The flowmeter performs measurements with a high resistance to noise from causes such as sharp temperature fluctuations or vibration. Additionally, the flowmeter offers superior durability due to lack of moving parts.

A temperature sensor and mass flow compensation calculation feature are built in. The steam temperature is detected and a real-time automatic mass flow compensation is carried out in response to fluctuations in the specific volume of the saturated steam.

DSC (Differential Switched Capacitance) Sensor Measures Velocity of Flow

A series of vortices is periodically shed downstream from alternate sides of a bluff body (vortex shedder) placed in the middle of the flow. These vortices are called von Karman vortices. A vortex flowmeter makes use of the directly proportional relationship between the shedding frequency of the von Karman vortices and the velocity of the fluid in the pipe (volumetric flow rate) under the correct conditions. It is possible to get an accurate measurement of the flow rate by measuring the shedding frequency of the von Karman vortices.

 

Velocity and Shedding Frequency of von Karman Vortices

Click on the buttons above to see the differences in the frequency vortices are shed depending on the velocity of flow.

Flow Rate Compensation by Temperature Sensor and Mass Flow Compensation Calculation Feature

Vortex flowmeters measure the flow velocity and display the measured flow rate as the volumetric rate of flow. However, the amount of steam is normally displayed as a mass flow rate using units such as kg/h or t/day. Consequently, if the value of its specific weight is used when measuring steam, it is then necessary to perform a unit conversion to mass flow rate. The specific weight of steam varies greatly depending on the steam pressure, so when measuring the flow rate of steam that is undergoing pressure fluctuations, it is not possible to achieve an accurate mass flow rate if calculations involve only a single specific weight.

The graph below shows the true specific weight values and the deviations of steam at a constant flow rate over a range of pressures from 0.3 MPaG to 0.7 MPaG, at a specific weight value of 0.5 MPaG for the purposes of unit conversion. As we can see from the graph, though the deviation is zero at a pressure of 0.5 MPaG, the deviation grows larger as the pressure moves away from 0.5 MPaG in either direction.

The point of doing mass flow compensation is to be able to perform calculations using the correct specific weight in real time. In the case of saturated steam, the specific weight can be identified if either the temperature or the pressure is known. To identify the specific weight of superheated steam, it is necessary to know both the temperature and the pressure.

Universal Mounting Position

The installation angle of the display section can be selected using notches located at 45° intervals on the display head, as can be seen by moving the mouse around on the picture of the flowmeter.

Note: There may be restrictions on the mounting position depending on the flow medium used.

Realization of Reduction in Total Cost

• DC24V power source OK
• No need for onsite setup during installation
• No need for installation of a box for the display or impulse lines as with an orifice flowmeter