Method for measuring wet natural gas flow rate by combining ultrasound with target flowmeter

Abstract

The invention discloses a rectification-technology-based method for measuring a wet natural gas flow rate by combining ultrasound with a target flowmeter. A measuring system includes an inverted U-shaped measuring pipeline, a nozzle rectification machine, an ultrasound flowmeter, the target flowmeter, a pressure sensor, a temperature sensor and the like. The nozzle rectification machine, the ultrasound flowmeter and the target flowmeter are mounted at the descending side of a U-shaped measuring pipe. Wet gas flows through the nozzle rectification machine and is adjusted into approximate homogeneous phase flow; when ultrasonic is propagated, the ultrasonic flowmeter which works in a transit time mode measures the apparent volume flow rate of the wet gas; in combination with the apparent volume flow rate measured by the ultrasonic flowmeter, the target flowmeter measures the apparent density of the wet gas; under the conditions that gas-phase components of the wet gas are known, the liquid phase is incompressible and the liquid-phase density is known, according to pressure and temperature parameters, the gas-phase density can be calculated; finally, according to the apparent volume flow rate and apparent density of the wet gas, the liquid-phase density and the gas-phase density, a liquid-phase volume fraction, a liquid-phase volume fraction, a liquid-phase volume flow rate, a liquid-phase mass flow rate, a gas-phase volume flow rate and a gas-phase mass flow rate are calculated, and therefore the online non-separation measurement of the wet natural gas flow rate is achieved.

Description

technical field [0001] The invention relates to the technical field of natural gas flow measurement, in particular to the combined wet natural gas flow measurement technology based on rectification technology and ultrasonic and target flowmeter. Background technique [0002] In the field of oil and gas metering, wet natural gas (hereinafter referred to as wet gas) is a special gas-liquid two-phase flow form, generally referring to the oil-gas mixture with a volume fraction of the gas phase greater than 90% and a volume fraction of the liquid phase and other components of less than 10%. . The American Petroleum Institute defines the gas-liquid two-phase flow of Lockhart-Martinelli (L-M) parameters as wet gas. Although the volume content of liquid phase components is usually small, its dynamic characteristics are extremely complex due to the existence of liquid phase which increases the instability of moisture flow. Due to the gravity of the droplet and the surface tension o...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: first, it is corrected according to the experimental results without a clear kinetic mechanism; second, it does not correct the liquid phase flow rate; third, this method is only applicable to a narrow section with high gas content range

However, this technology has relatively high requirements on the experimental site and equipment, and the maintenance and use are more complicated.

There are also some technologies that may have a risk of radiation, which will affect the health of the staff

[0007] Due to the existence of liquid phase, the error of moisture measurement is large, and it cannot even be measured when the proportion of liquid phase is large.

At present, the wet gas flowmeter still needs to be corrected according to the actual working conditions. The structures of the wet gas flowmeters are different, and the mathematical models are also different, and the adaptability to the working conditions is not strong.

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