Turbine Flow Meter Measurement of Steam Flow

Turbine flow meter in a certain flow range vortex separation frequency is proportional to the average flow rate in the pipeline, the vortex generating body into the capacitive probe or piezoelectric probe (detector) and configure the corresponding circuit, which constitutes the capacitive detection turbine flow Meter or piezo-detection turbine flow sensor.
In order to ensure a complete measurement function, the flow pattern at the entrance should not be disturbed. The length of the upstream straight section should be approximately 15 times the diameter of the turbine flowmeter (D), and the length of the downstream straight section should be approximately 5 times the flowmeter diameter (D). When a non-streamline vortex sounder is placed in the fluid, two rows of regular vortices are generated alternately from both sides of the vortex. This vortex is called a Karman turbine.

The verification technology of steam flowmeters is currently still in the research stage in China. Some domestic production plants have successively established standard devices using steam as the working medium. However, due to high energy consumption and poor working conditions, they are striving to find new ways to use air as their working medium. According to investigations, there are mainly two types of standard devices that use air as the working medium.

One type is the sonic nozzle type. Although the measurement accuracy of the device satisfies the measurement requirements, the device has a high build rate of about one million units per unit. Practice has proved that the technology is feasible, but the investment costs and management and operation costs are huge, and it is impossible for general measurement verification agencies to adopt them universally.

Another type is the blower orifice plate type. Although the cost is not high but the accuracy is low, combined with the pressure loss of this type of device, and the pressure of the wind source is low, the measurement range often fails to meet the verification requirements. The national measurement department has confirmed this. In addition, some domestic companies are also seeking to use vortex flowmeters instead of nozzles or orifice plates to try, but the use of parameters is not yet mature.

In order to solve the above problems of steam metering, Changzhou Liangbang Instrument and Nanjing Quality and Technical Supervision College cooperated to develop the LDQ gas flow standard device. For the first time, turbine flowmeters were used in the transmission of gas (including steam) flow values, and satisfactory results were obtained. Its advantages are as follows:

1. This device adopts turbine flow meter as the transmission standard. It has the advantages of wide measuring range, small pressure loss, good repeatability, etc. It overcomes the defects of large pressure loss and insufficient range of other types of devices, and its cost is low. Its investment is sonic nozzle type. The device is about 20%.

2. The main error of the standard table (system error) is eliminated by the error tracking method, which greatly improves the measurement accuracy of the device.

3. The air-steam conversion factor for the transfer of steam flow values ​​is determined by a large number of experimental data through regression processing, and the confidence is relatively high.