CN102052951B - Measurement device and method for multi-phase interface liquid level based on dual-modality sensor - Google Patents

Abstract

The invention belongs to the technical field of multi-phase interface liquid level measurement, and relates to a multi-phase interface liquid level measurement device based on a capacitance/resistance dual-mode sensor, which is used to measure the liquid level of a multi-phase interface, including a host computer, a signal generator Unit, power amplifier, analog multi-way switch, capacitive/resistive dual-mode sensor and signal acquisition unit, characterized in that the capacitive/resistive dual-mode sensor includes N rows and 3 columns distributed on the same plane Electrode array, N is an integer greater than or equal to 3, wherein the electrodes in the first column and the second column are all rectangular electrodes, and the electrodes in the third column are circular in shape, and their size is smaller than that of the first column and the second column The electrodes located in the same column are electrodes of the same material and size, and the distance between the electrodes is also the same. The invention also provides a method for measuring the liquid level of the multi-phase interface realized by the above-mentioned measuring device. The invention has simple and reliable structure, convenient installation, is not easy to be blocked by viscous crude oil, and can realize accurate measurement of multiphase interface liquid level.

Description

A device and method for measuring multi-phase interface liquid level based on dual-mode sensor

technical field

The invention belongs to the technical field of multiphase interface liquid level measurement, and relates to a measurement system based on a capacitance/resistance dual-mode sensor.

Background technique

The crude oil directly extracted from the oil well contains a large amount of water, sediment and natural gas, and through the separation of the three-phase separator, several interfaces such as sediment/water, water/oil, natural gas/oil, etc. will be formed in the oil storage tank . In order to determine the amount of crude oil in the oil storage tank, it is necessary to first measure the upper and lower liquid levels of the crude oil in the oil storage tank. Obviously, in order to achieve this goal, it is necessary to design a multi-interface measurement and control system.

At present, the traditional capacitive liquid level measurement system can only detect the position of a single interface. When detecting the position of multi-phase interface at the same time, only one pair of electrodes cannot achieve the goal. Using the multi-electrode sensor structure (plus references), it is theoretically possible to distinguish the gas/oil/water interface, but the water directly produced from the oil well is mainly seawater, which has a high conductivity (up to 5 simon/m ), due to the conductive short-circuit effect of water, the measured capacitance value is not proportional to the dielectric constant of water, and is often much smaller than the theoretical value. Therefore, in practice, the measured capacitance cannot accurately distinguish the seawater/oil interface.

Contents of the invention

In view of the defects and deficiencies in the prior art mentioned above, the object of the present invention is to propose a measuring device using a capacitance/resistance dual-mode sensor. The invention can accurately distinguish the gas/oil interface by using the capacitance measurement, and can accurately distinguish the water/oil interface by using the resistance measurement. The present invention adopts following technical scheme:

A multi-phase interface liquid level measuring device based on a capacitance/resistive dual-mode sensor is used to measure the liquid level of a multi-phase interface, including a host computer, a signal generating unit, a power amplifier, an analog multi-way switch, a capacitance/resistance A dual-mode sensor and a signal acquisition unit, the capacitive/resistive dual-mode sensor includes an N×3 electrode array distributed on the same plane, where N is an integer greater than or equal to 3, wherein the first column and The electrodes in the second column are all rectangular electrodes, and the electrodes in the third column are circular in shape, and their size is smaller than that of the electrodes in the first and second columns. The electrodes in the same column are electrodes of the same material and size, and the distance between electrodes is also the same. Same; when measuring, place the sensor vertically in the multiphase liquid to be measured, and control the analog multiplex switch from bottom to top to strobe the electrodes in the first column or an electrode in the second column in turn by the host computer, and Simultaneously strobe another electrode in the same row as the selected electrode but in the third column; apply an excitation voltage signal to the two gated electrodes through the signal generation unit and power amplifier, and collect the two electrodes by the signal acquisition unit The induced current is sent to the upper computer, and the upper computer measures the liquid level of the multi-phase interface according to the collected induced current.

The measuring device of the multiphase interface liquid level based on the capacitive/resistive dual-mode sensor is characterized in that, the capacitive/resistive dual-mode sensor has 9-90000 electrodes, and each electrode is made of a metal sheet Made, the thickness is 0.0001-1mm.

The present invention also provides a method for measuring the liquid level of a multi-phase interface realized by using the capacitance/resistance dual-mode sensor, comprising the following steps:

(1) Calibrate the induced current value of pure gas and pure oil. This step can be completed before the experiment. Take any pair of rectangular electrodes, place them in pure gas and pure oil respectively, apply an excitation signal at one end, and measure the induction at the other end. The signal is stored in the host computer, assuming that the induced current values of pure gas and pure oil are I _a and I _o respectively;

(2) Use the resistance mode to find the height of the lower liquid level of the oil: the upper computer controls the analog multi-way switch to select the electrodes in the second column and the two electrodes in the same row in the third column from bottom to top, and apply Excitation signal, and sequentially measure the induced current value sequence I, when I>0, pause, at this time, the height of the lower liquid level of the oil can be obtained as h ₁ =m×(a-1), m is the electrode gap of the third row of electrodes Distance, a is the serial number of a row of electrodes gated when I>0, and the numbering method is from bottom to ascending sequence, a∈(1, 2L, N);

p为第二列电极的极间距离，H为矩形电极的宽度，b为当0＜I′＜1时选通的电极编号，b∈(a，L，N)；(3) Use the capacitive mode to find the height of the upper liquid level of the oil, and the host computer controls the analog multi-way switch to select the electrodes in the same row in the first column and the second column from a to the upper, apply the excitation signal, and sequentially Measure the induced current value sequence I′; make When 0<ξ<1, stop, at this time, the upper liquid level of the oil can be obtained

p is the distance between the electrodes of the second column, H is the width of the rectangular electrodes, b is the electrode number selected when 0<I'<1, b∈(a, L, N);

(4) Finally, use h=h ₂ −h ₁ to obtain the liquid level height of crude oil.

The biggest advantage of the present invention is that the capacitive/resistive dual-mode sensor is designed as a single-polar plate type, so the structure is simple and reliable, the installation is convenient, and it is not easy to be blocked by viscous crude oil. Relatively speaking, this technique is more practical and convenient, and it is one of the most feasible measurement tools for multiphase interface liquid level.

Description of drawings

Fig. 1 is a schematic diagram of a system device based on a dual-mode sensor of the present invention;

Fig. 2 is a schematic diagram of a dual-mode sensor;

Fig. 3 is a schematic diagram of the simulated multi-phase interface to be measured.

Specific implementation method

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic diagram of a device based on a dual-mode sensor system according to the present invention. It consists of a host computer 1, a signal generating unit 2, a power amplifier 3, an analog multi-way switch 4, a capacitive/resistive dual-mode sensor 5 and a signal acquisition unit 6. The signal generation unit adopts direct digital synthesis (DDS) chip AD7008, which can generate sinusoidal excitation signals with different amplitudes and phases. The amplitude and phase of the excitation signal can be set by a computer, amplified by a power amplifier and installed on the excitation electrode array 8 . The computer controls the signal acquisition unit to collect the induced current value for the electrode arrays 7 and 9 .

Adhere N×3 electrode arrays on the same plane (N is an integer greater than or equal to 3) on the insulating plate 10, the electrode arrays 7, 8 are rectangular in shape, and the electrode array 9 is circular, as shown in Figure 2 . The capacitive/resistive dual-mode sensor is composed of uniformly arranged electrode arrays. The number of electrodes is 9-90000. The electrodes are made of metal sheets with a thickness of 0.0001-1mm. The size of the measured liquid depends on the number of electrodes. Depending on the surface height, the size of the electrode array 9 is much smaller than the size of the electrode arrays 7 and 8 . The insulating plate is made of non-conductive material, such as plastic.

p为矩形电极阵列的极间距离，H为矩形电极的宽度，b为当0＜I′＜1时选通的电极编号，b∈(a，L，N)，I_a、I_o为标定纯气体及纯油时的感应电流值。标定过程为取一对矩形电极，分别置于纯气体和纯油中，一端施加激励信号，测量另一端的感应信号。最后利用h＝h₂-h₁得到原油的液位高度。For the measurement of the liquid level of the multiphase interface, the measurement of the most special oil liquid level in the gas/oil/water three-phase is given here, and the present invention is also applicable to the measurement of other multiphase interfaces. As shown in Figure 3, the gas/oil/water three-phase liquid measures the liquid level of the oil by using the dual modes of the resistance sensor and the capacitance sensor respectively, and uses the resistance mode to obtain the height of the lower liquid level of the oil, and the host computer controls the simulation The multi-way switch sequentially selects the electrode array 8 from bottom to top, applies the excitation signal, and sequentially measures the induced current value sequence I of the electrode array 9. When I>0, pause, and the height of the lower liquid level of the oil can be obtained at this time as h ₁ = m × (a-1), m is the distance between the electrodes of the electrode array 9, a is the number of electrodes selected when I>0, a∈(1, 2L, N); For the height of the upper liquid level of the oil, the upper computer controls the analog multi-way switch from a to the upper strobe electrode array 8 in turn, applies the excitation signal, and measures the induced current value sequence I' of the electrode array 7 in sequence, when 0<I'<1 , pause, at this time, the upper liquid level of the oil can be obtained as

p is the inter-electrode distance of the rectangular electrode array, H is the width of the rectangular electrode, b is the electrode number selected when 0<I'<1, b∈(a, L, N), I _a and I _o are calibration Induction current value for pure gas and pure oil. The calibration process is to take a pair of rectangular electrodes, place them in pure gas and pure oil respectively, apply an excitation signal at one end, and measure the induction signal at the other end. Finally, h=h ₂ -h ₁ is used to obtain the liquid level height of crude oil.

Measurement method of the present invention specifically comprises the following steps:

(1) First, calibrate the induced current value of pure gas and pure oil. This step can be completed before the experiment. Take a pair of rectangular electrodes, place them in pure gas and pure oil respectively, apply an excitation signal at one end, and measure the The induction signal is stored in the host computer, assuming that the induction signal values of pure gas and pure oil are I _a and I _o respectively;

(2) Next, use the resistance mode to find the height of the lower liquid level of the oil, and the host computer controls the analog multi-way switch to select the electrode array 8 from bottom to top in turn, apply the excitation signal, and measure the induced current value sequence of the electrode array 9 in sequence I, when I>0, pause, at this time the height of the lower liquid level of the oil can be h ₁ =m×(a-1), m is the distance between the electrodes of the electrode array 9, a is selected when I>0 Common electrode number, a∈(1, 2L, N);

p为矩形电极阵列的极间距离，H为矩形电极的宽度，b为当0＜I′＜1时选通的电极编号，b∈(a，L，N)；(3) Utilize the capacitive mode again to obtain the upper liquid level height of the oil, and the host computer controls the analog multi-way switch from a to the upper strobe electrode array 8 in turn, applies the excitation signal, and measures the induced current value sequence I of the electrode array 7 in sequence ’, when 0<I’<1, pause, at this time, the upper liquid level of the oil can be obtained as

p is the distance between the electrodes of the rectangular electrode array, H is the width of the rectangular electrode, b is the electrode number selected when 0<I'<1, b∈(a, L, N);

(4) Finally, use h=h ₂ −h ₁ to obtain the liquid level height of crude oil.

Claims (2)

1. A measuring device for multi-phase interface liquid level based on capacitive/resistive dual-mode sensor, used to measure the liquid level of multi-phase interface, including host computer, signal generating unit, power amplifier, analog multi-way switch, capacitor /resistive dual-mode sensor and signal acquisition unit, characterized in that the capacitive/resistive dual-mode sensor includes an N×3 electrode array distributed on the same plane, where N is an integer greater than or equal to 3, Among them, the electrodes in the first column and the second column are all rectangular electrodes, the electrode shape of the third column electrode is circular, and its size is smaller than the electrodes in the first column and the second column, and the electrodes in the same column are made of the same material and size. The electrodes and the inter-electrode spacing are also the same; when measuring, place the sensor vertically in the multiphase liquid to be measured, and the upper computer controls the analog multi-way switch to strobe the electrodes in the first column or the electrodes in the second column sequentially from bottom to top. One electrode, and at the same time gate another electrode in the same row as the selected electrode but in the third column; apply an excitation voltage signal to the two gate electrodes through the signal generation unit and power amplifier, and collect them by the signal acquisition unit The induced currents of the two electrodes are sent to the upper computer, and the upper computer measures the liquid level of the multi-phase interface according to the collected induced currents. 2. The measuring device of the multiphase interface liquid level based on the capacitive/resistive dual-mode sensor according to claim 1, characterized in that, for the capacitive/resistive dual-mode sensor, the number of electrodes is 9-90000 Each electrode is made of sheet metal with a thickness of 0.0001-1mm.

Images