Effect of noise on gas ultrasonic flowmeter

Work in high pressure and large traffic QiZhan as births, machinery and equipment transformer and basins in the oil and gas pipelines caused by noise will cause certain harm of gas ultrasonic flowmeter work, lead to instability of flow meter test results, reduced the frequency stability of flow meter, greatly reduced the precision of gas ultrasonic flowmeter measurement precision.In this paper, the basic principle of gas ultrasonic flowmeter is introduced in detail, and the reason caused by noise is analyzed.

Crude oil is the key power source of chemical plant in modern industrial production and life.As a new type of flowmeter, the gas ultrasonic flowmeter not only has a wide range of detection, but also has the advantages of high quality pressure, high precision and double flow measurement.

Effect of noise on gas ultrasonic flowmeter

The basic principle of gas ultrasonic flowmeter

 

Gas ultrasonic flowmeter is a kind of spread using time difference and execution of hydrocarbon gases, such as gas meter, water flow traffic detection is based on ultrasonic ultrasonic transducer replacement, keep the ultrasonic single pulse charging and send, and spread with ultrasonic current in oil and gas material and put back the clock of time water flow calculation, and finally calculate the oil and gas flow, total flow.In the process of oil and gas pipeline processing, the source of noise includes pressure regulating valve, throttle stop valve and other pipeline positions.The key factors that jeopardize the accuracy of accurate measurement of the gas ultrasonic flowmeter are the rate pervasion and vortexes of the flow conditions on the spot.In order to deal with this problem, multi-channel equipment is usually used in practical operation, as shown in figure 1, to reduce the harm of ultrasonic velocity vortex to the detection precision.

 

Cold said ultrasonic flowmeter cold said layout

 

The root cause of noise

 

In general, the ultrasonic noise generally comes from within the material being tested and noise comes from the pressure regulating valve and meter two position switch power supply power supply system, when the pressure regulating valve and relief valve intercept caused by high frequency ultrasound and the output power of the flowmeter, press close to the flow AGC limit will reduce, to produce gas ultrasonic flowmeter dry scratching noise reducing the precise measurement of the flow meter high efficiency.

 

Noise reduction improvement and prevention measures

 

Install pressure regulating valve to ensure installation interval

 

Reducing noise is the main way of considering the pressure regulating valve, and installed in the middle and lower reaches of gas ultrasonic flowmeter, pressure after metrological verification first, in accordance with GB/T18604-2014 "with gas ultrasonic flowmeter accurately measure the total flow of oil and gas related requirements:" if the manufacturer production flow meter is not show on the middle and lower reaches of over length information content, under the standard of regulator without liquidity, upstream and downstream flow meter to take over the period of at least should have at least 50 d specifications;"In the case of the flow regulator, the upstream and downstream connection sections of the flow meter should have a minimum of 30D and the downstream connection sections should have a minimum of 5D."

 

Refit "T" head to reduce noise kinetic energy

 

At a certain level, the transmitting point efficiency of the "T" bend will weaken the kinetic energy of noise propagated upward and downstream, thus greatly reducing the monopulse harm of noise to ultrasonic waves.If carbon dioxide and water content in oil and gas are high, water will be stored in the oil and gas delivery pipe. If the "T" bend pipe adopts the method of burying underground, it is very easy to cause water storage in the pipeline. However, carbon dioxide dissolved in water under high temperature standard will easily lead to the adverse effect of pipeline erosion.Therefore, the "T" bend is best installed in the road as shown in figure 2.

 

Road mounting plan for "T" type

 

Refit 90℃ bend pipe to improve anti-noise working ability

 

In order to improve the noise resistance of the flowmeter, it is highly recommended to refit the 90℃ bend.In the specific steps, the 90℃ bend pipe is installed in the middle of the flow meter and the filter device, so that the noise sound wave frequency can be changed in the relative path of the oil and gas pipeline, thus weakening its diffusion kinetic energy.It is important to note that during the spot installation, the length of the connection must be taken into account and the installation requirements of the flow meter must be considered to ensure that the flow meter is maintained in the best possible condition.

 

Add noise reduction device to ensure all normal operation

 

Nowadays, among the noise sources that endanger the actual operation of the gas ultrasonic flowmeter, the noise frequency section caused by the electric pressure regulating valve is the largest.Therefore, it is necessary to protect the noise of pressure regulating valve.For example, some gas ultrasonic flowmeters installed in a station and pressure regulating valve have a certain interval, can be installed in the indoor space noise reduction machine equipment, so as to reduce the noise data signal strength, with continuous noise reduction effect.

 

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