分流式電磁流量計(jì)在石油行業(yè)的應(yīng)用

Application of shunt electromagnetic flowmeter in petroleum industry

在石油行業(yè)的流量測(cè)量工作上，油和水兩相混合流動(dòng)的現(xiàn)象非常常見(jiàn)，那么如何進(jìn)行油水兩相流流量的測(cè)量？在石油行業(yè)應(yīng)用廣泛的電磁流量計(jì)又是怎樣發(fā)揮作用的呢？

In the flow measurement of oil industry, the phenomenon of oil and water two-phase mixed flow is very common, so how to measure the flow rate of oil-water two-phase flow? How does electromagnetic flowmeter, which is widely used in petroleum industry, play a role?

在進(jìn)行油水兩相流流量測(cè)量時(shí)存在著難題。在測(cè)量油水混合液體時(shí)，如果含水量較高且流過(guò)電磁流量計(jì)傳感器的流速足夠高，就可以達(dá)到理想的測(cè)量效果，但是在低流速或者含水量較低的情況下，就會(huì)存在較大的測(cè)量誤差。而如果能夠采用分流的測(cè)量方法，那么就能更好的用流量計(jì)進(jìn)行油水兩相流流量的測(cè)量。

There are some difficulties in the measurement of oil-water two-phase flow. In the measurement of oil-water mixed liquid, if the water content is high enough and the flow rate through the electromagnetic flowmeter sensor is high enough, the ideal measurement effect can be achieved, but in the case of low flow rate or low water content, there will be large measurement error. If the split flow measurement method can be used, the flowmeter can be better used to measure the flow rate of oil-water two-phase flow.

既然采用分流方式能夠降低電磁流量計(jì)的流量測(cè)量下限，并且可以拓寬含水率的應(yīng)用范圍，那么具體怎樣進(jìn)行分流，下面小編會(huì)進(jìn)行詳細(xì)的講解：

Since the flow measurement lower limit of electromagnetic flowmeter can be reduced and the application range of water content can be widened by using the diversion method, the following small group will explain in detail how to carry out the diversion:

分流式電磁流量計(jì)機(jī)械結(jié)構(gòu)設(shè)計(jì)使在低流量時(shí)，在有滑脫作用的情況下使輕質(zhì)相的油在傘布下聚集，當(dāng)堆積到上進(jìn)液口的位置時(shí)，上部的油相從上進(jìn)液口處流入，流經(jīng)儀器內(nèi)壁與分流管形成的環(huán)形空間，受上封隔器的阻隔作用，油從下出液口流出，傘布下含有一部分油的水相受下封隔器的阻隔作用，從下進(jìn)液口流入分流管，進(jìn)入電磁流量傳感器流道，流經(jīng)電磁流量傳感器，流體經(jīng)電磁流量傳感器檢測(cè)后，由上出液口流出，完成流量測(cè)量。通過(guò)分流掉一部分油的方法使流經(jīng)電磁流量傳感器內(nèi)流體的含水率得到提高，從而提升了測(cè)量準(zhǔn)確度。

The mechanical structure design of the shunt electromagnetic flowmeter enables the oil of light phase to accumulate under the umbrella cloth under the condition of slippage when the flow rate is low. When it accumulates to the position of the upper liquid inlet, the upper oil phase flows in from the upper liquid inlet and flows through the annular space formed by the inner wall of the instrument and the shunt pipe. Under the blocking effect of the upper packer, the oil flows out from the lower liquid outlet, and there is a part under the umbrella cloth The water phase of oil separation, blocked by the lower packer, flows into the diversion pipe from the lower inlet port to the flow passage of the electromagnetic flow sensor, and flows through the electromagnetic flow sensor. After being detected by the electromagnetic flow sensor, the fluid flows out from the upper liquid outlet to complete the flow measurement. By diverting part of the oil, the water content of the fluid flowing through the electromagnetic flow sensor is improved, and the measurement accuracy is improved.

電磁流量計(jì)投運(yùn)注意事項(xiàng)

Precautions for operation of electromagnetic flowmeter

之前我們?cè)?jīng)講解過(guò)，在選購(gòu)電磁流量計(jì)和現(xiàn)場(chǎng)安裝需要注意的一些事項(xiàng)，那么除此之外，在流量計(jì)投運(yùn)前需要進(jìn)行哪些方面的檢查呢？下面我們就電磁流量計(jì)投運(yùn)前后常見(jiàn)的問(wèn)題進(jìn)行簡(jiǎn)單的講解。

We have explained some matters needing attention in purchasing electromagnetic flowmeter and field installation. In addition, what kind of inspection should be carried out before the flowmeter is put into operation? We will briefly explain the common problems before and after the electromagnetic flowmeter is put into operation.

在使用過(guò)程中，可能會(huì)出現(xiàn)電磁流量計(jì)安裝使用的一年時(shí)間基本沒(méi)有出現(xiàn)故障問(wèn)題，但是工作一年后則出現(xiàn)異常情況的狀況，如果不是因?yàn)闇y(cè)量管道不滿管、介質(zhì)里邊含有氣體等原因，那么就需要考慮是不是電纜線出現(xiàn)故障。如果沒(méi)有做好流量計(jì)傳感器和轉(zhuǎn)換器的電纜接頭處的防潮防水工作，就很有可能會(huì)出現(xiàn)下述測(cè)量不穩(wěn)定的情況：

In the process of use, the electromagnetic flowmeter may be installed and used for one year without failure, but after one year of operation, there will be abnormal conditions. If it is not because the measurement pipe is not full of pipe and there is gas in the medium, it is necessary to consider whether the cable is faulty. If the cable joints of flowmeter sensor and converter are not well protected from moisture and water, the following unstable measurement conditions may occur:

1、測(cè)量結(jié)果偏小。這主要是由于信號(hào)線對(duì)地絕緣下降引起信號(hào)衰減、勵(lì)磁線圈對(duì)地絕緣下降以及勵(lì)磁電流下降，從而造成測(cè)量結(jié)果偏小；

1. The measurement result is too small. This is mainly due to the decrease of signal line to ground insulation, the decrease of excitation coil insulation to ground and the decrease of excitation current;

2、測(cè)量結(jié)果波動(dòng)。信號(hào)電纜連接處接觸電阻不穩(wěn)定、勵(lì)磁回路電纜連接處接觸電阻不穩(wěn)定，從而造成測(cè)量結(jié)果出現(xiàn)波動(dòng)；

2. The measurement results fluctuated. The contact resistance of the signal cable connection is unstable, and the contact resistance of the excitation circuit cable connection is unstable, which causes the measurement results to fluctuate;

為了避免以上測(cè)量不穩(wěn)定情況的出現(xiàn)，應(yīng)在電磁流量計(jì)投運(yùn)前就應(yīng)對(duì)測(cè)量管道和流量計(jì)進(jìn)行檢查，檢查管道雜物是否清理干凈，電極處是否做好防潮防水工作，電氣線路接地是否可靠，是否做好絕緣電阻及接地電阻的測(cè)試等，這類異常情況的判別需要深入現(xiàn)場(chǎng)進(jìn)行檢查排除。

In order to avoid the instability of the above measurement, the measurement pipeline and flowmeter should be inspected before the electromagnetic flowmeter is put into operation, to check whether the pipeline sundries are cleaned up, whether the electrode is well moistureproof and waterproof, whether the electrical circuit grounding is reliable, and whether the insulation resistance and grounding resistance test are done well. The discrimination of such abnormal conditions needs to be carried out on site Check and eliminate.