Steam flow control. Equipment for measuring steam flow

Main Characteristics and Specifics of Accounting for Saturated and Superheated Steam

Measuring steam is complicated by its high temperature and pressure, which also affect other properties of the measured medium.

If the dryness fraction of saturated steam drops below 70%, this may be a consequence of changes in the technological process, which can lead to the formation of a two-phase medium. Such situations often arise due to damage to pipe insulation or incorrect selection of pipeline diameter, which can cause a drop in steam temperature or pressure.

In addition, corrosion and scale deposits can distort the flow, creating mechanical obstacles. Shock loads from thermal and hydraulic factors are also possible. Therefore, steam measuring instruments must be durable enough to operate under such conditions. According to current standards, steam metering devices must be able to adjust their readings considering changes in temperature and pressure to ensure high measurement accuracy.

Steam Volume Analysis: Applied Methods

There are many methods for steam assessment in industry, but the choice of appropriate flow meters for accurate accounting remains quite limited.

There are two most common methods for measuring steam flow: using differential pressure devices and vortex meters.

The first method involves installing a differential pressure device inside the pipeline. Such devices typically include diaphragms, although nozzles, Venturi tubes, and other types of local hydraulic resistances can also be used.

When passing through the diaphragm, the flow changes its characteristics. An increase in pressure is observed before the differential device, and a decrease after it. The pressure difference before and after the diaphragm is directly related to the volume of steam passing through.

The second approach to measuring steam flow uses the principle of vortex flow meters, which is based on the effect of vortex formation when a body of a certain shape is placed in the flow of the measured medium. Vortices alternate on both sides behind the obstacle in the flow. The frequency of their formation is directly related to the flow velocity. By measuring pressure oscillations induced by the vortex flow behind the obstacle, the flow velocity and, accordingly, the steam flow rate can be calculated.

When using vortex flow meters for steam accounting, it is also important to consider the pressure and temperature of the medium under operating conditions. These data are entered into the thermal calculation, which allows determining the mass of steam or the amount of thermal energy contained in it.

To estimate the mass of saturated steam, it is sufficient to use one external sensor, since there is a strict relationship between steam pressure and temperature.

In most cases, algorithms for calculating steam parameters are already included in the software of analyzers or controllers that are part of measurement systems. However, in the products of the vortex flow meter series «IZMERKON», these algorithms are embedded within the software of the electronic converter module, which is an integral part of the flow meter itself.

Thanks to the integration of algorithms into the electronic unit with computing functions, the vortex flow meter IZMERKON VT 470 has the ability to independently perform the necessary adjustments and calculations.

In addition to internal algorithms, vortex flow meters provide a number of additional advantages:

• support for remote data transmission, including the use of wireless technologies;
• application of digital signal processing to improve measurement accuracy;
• provision of free specialized software for working with the devices.

Steam Metering Unit Based on Vortex Flow Meters

The company «IZMERKON» offers the supply of vortex flow meters IZMERKON VT 470 series, which are registered in the State Register of Measuring Instruments and designed for measuring steam flow.

We provide various technical solutions for steam accounting and strive to fully meet the requests and expectations of clients, following key principles:

• selection of the most suitable technical solution considering its feasibility;
• ensuring economic benefit for the client;
• ensuring safety in the industrial sphere during equipment use.

If you have any questions regarding the operation of flow meters or accounting systems, please contact our engineers for the necessary additional information by phone +7 (812) 309 56 05 or via the feedback form.