This paper discusses the problems that should be paid attention to when the intelligent vortex flowmeter is used for steam measurement. The methods of temperature and pressure compensation are discussed. This paper analyzes the measurement error caused by the change of instrument constant caused by the change of temperature and pipe diameter, points out the correction method, and discusses some specific problems in the actual measurement of steam.

The intelligent vortex flowmeter is widely used in steam measurement because of its convenient installation, wide measurement range, high accuracy, good repeatability and easy maintenance. Based on the measurement principle of vortex flowmeter and the unique properties of steam, the following problems should be paid attention to in order to achieve accurate measurement, especially for the meters of trade settlement.

Reasonable selection and installation of flowmeter is the premise of accurate measurement of steam

1.1 flowmeter selection

The principle is to select caliber based on flow, but the following two conditions shall be met.

1.1.1 requirements for pipe Reynolds number

1.1.2 requirements for steam flow rate in pipeline

1.2 flowmeter installation

The principle is to ensure straight pipe section and avoid vibration source and electromagnetic interference. The straight pipe section has the function of rectifying. To keep a certain straight pipe section is to keep the steam flowing in the pipe.

1.2.1 installation selection of pressure tap position

1.2.2 installation and selection of temperature measuring port

2. Automatic compensation of temperature and pressure is the guarantee of accurate measurement of steam

In trade settlement, steam is measured by mass flow m Q. For vortex flowmeter, the actual measured volume flow is v Q, and then the mass flow is calculated.

2.1 temperature and pressure compensation of saturated steam

3.1 error of pipe inner diameter introduction

3.2 functions of flow totalizer as trade settlement

In order to reduce the dispute of steam measurement trade, the following functions can be added to the flow totalizer:

① power off memory function, so as to check the power off and transmission time of flowmeter;

② the function of using steam to judge, because the vortex flowmeter is easy to be affected by vibration, it can judge whether there is steam flow in the pipeline and whether there is internal leakage of the valve according to the temperature and pressure parameter values, so as to eliminate the impact of vibration when the user does not use steam.

③ small flow complements the recording function. When the instantaneous flow is less than the measurable flow of vortex flowmeter, the automatic accumulation of the guaranteed minimum amount of user agreement can be realized.

④ super flow double recording function, when the instantaneous flow exceeds the agreed steam consumption, automatic accumulation of double metering can be realized according to the regulations.