CN112378464A - Small flow meter measuring device combined with uniform-velocity tube flow meter and method thereof - Google Patents
Small flow meter measuring device combined with uniform-velocity tube flow meter and method thereof Download PDFInfo
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- CN112378464A CN112378464A CN202011039043.2A CN202011039043A CN112378464A CN 112378464 A CN112378464 A CN 112378464A CN 202011039043 A CN202011039043 A CN 202011039043A CN 112378464 A CN112378464 A CN 112378464A
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- 238000000034 method Methods 0.000 title claims abstract description 8
- 238000005259 measurement Methods 0.000 abstract description 15
- 238000001514 detection method Methods 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 8
- 238000012544 monitoring process Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000013112 stability test Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
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- 238000000691 measurement method Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/02—Compensating or correcting for variations in pressure, density or temperature
- G01F15/022—Compensating or correcting for variations in pressure, density or temperature using electrical means
- G01F15/024—Compensating or correcting for variations in pressure, density or temperature using electrical means involving digital counting
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Abstract
The application discloses small flow meter metering device and method that combine uniform velocity tube flowmeter, relate to the instrument and measure technical field, aim at solves the problem that the measuring error that the small signal excision caused in the current measurement increases, install small flow meter metering device at uniform velocity tube flowmeter, small flow meter metering device includes first shut-off valve, the second shut-off valve, the third shut-off valve, the fourth shut-off valve, first blowoff valve, the second blowoff valve, the balanced valve, differential pressure transmitter and remote control end, read measurement differential pressure value through the remote control end and adjust the flow acquisition mode according to numerical value size, reduce the loss that the small signal excision caused, improve detection accuracy.
Description
Technical Field
The invention relates to the technical field of instrument measurement, in particular to a small flow meter measuring device combined with a uniform velocity tube flow meter and a method thereof.
Background
At present, the flow measurement by using the differential pressure principle is one of the most reliable flow measurement modes in the world, and represents that the products, namely the orifice plate and the uniform velocity tube flow meter, are widely applied. At present, most of large-scale enterprises adopt a uniform-speed pipe flowmeter with small pressure loss to reduce the pressure loss of a power energy medium pipe network to the minimum. However, the differential pressure of the uniform velocity tube flowmeter is small, a micro differential pressure transmitter is required to be matched for flow measurement, the flow and the differential pressure form an open square relationship, the smaller the flow, the larger the amplification factor is, the larger the measurement error is, and when the differential pressure transmitter has zero drift, false flow can be generated, so that the measured data is inaccurate. When the differential pressure operates at the bottom limit, the error and the theoretical error of flow measurement can reach 100%, the flow during the operation at the bottom limit is small, the total amount of the whole day is not greatly influenced, but the measurement error is larger under the condition that the operation at the bottom limit is carried out for a long time. In order to solve the influence of small signals on the metering data in engineering, return-to-zero processing is generally carried out, namely 10% of full-scale flow output is determined as a cut-off point. The small signal removal of the flow is a method for solving the contradiction of zero drift covering of the flow meter, the flow does not exist after the small signal removal is not adopted, and the measurement data is not counted, so that the effectiveness of the power energy measurement data of an enterprise is greatly influenced, various power energy of the enterprise is lost, the reasonable energy use of the enterprise cannot be met, and the cost accounting requirement is carried out.
Disclosure of Invention
The application discloses little flowmeter metering device who combines uniform velocity tube flowmeter, aim at solve loss and the measurement accuracy problem that the small-signal excision caused in the prior art.
In order to solve the problems, the following technical scheme is adopted in the application:
a small flow metering device combined with a uniform-velocity tube flowmeter comprises the uniform-velocity tube flowmeter and a small flow metering device, wherein the small flow metering device comprises a first cut-off valve, a second cut-off valve, a third cut-off valve, a fourth cut-off valve, a balance valve, a first blowdown valve, a second blowdown valve, a differential pressure transmitter and a remote control end;
two exit ends of the uniform velocity tube flowmeter are respectively provided with one end of a first cut-off valve and one end of a second cut-off valve, the other end of the first cut-off valve is connected with one end of a third cut-off valve through a pressure guide pipeline, the other end of the second cut-off valve is connected with one end of a fourth cut-off valve through a pressure guide pipeline, a balance valve and a differential pressure transmitter are installed between the other end of the third cut-off valve and the other end of the fourth cut-off valve, meanwhile, the first blowdown valve and the second blowdown valve are respectively connected through the pressure guide pipeline, and a remote control end is connected to.
Preferably, the differential pressure transmitter model is E + H PMD230 or EJA 120A.
Preferably, the remote control end comprises a distributor, a PLC controller and a user operation station, the differential pressure transmitter is connected with the distributor of the remote control end through a cable, the distributor is connected with the PLC controller through a cable, and the PLC controller is connected to the user operation station through a cable.
Preferably, the PLC controller model is SLC-500.
The application also provides a small flow metering method combined with the uniform velocity tube flowmeter, which is applied to the small flow metering device combined with the uniform velocity tube flowmeter and comprises the following steps:
(a) a differential pressure transmitter in the device transmits a measured differential pressure value to a PLC controller;
(b) the PLC judges the value transmitted by the differential pressure transmitter;
(c) if the measured differential pressure value in the step (b) is more than 0.5% and within 1% of the range of the differential pressure transmitter, switching the flow acquisition mode to a linear output mode;
(d) if the measured differential pressure value in the step (b) is larger than 1% of the measuring range of the differential pressure transmitter, switching the flow acquisition mode to a square root output mode;
(e) and (c) if the measured differential pressure value in the step (b) is less than 0.5% of the measuring range of the differential pressure transmitter, cutting off a small signal.
(f) And calculating the flow according to the flow acquisition mode and the measured differential pressure value.
The method has the advantages that the remote control end reads the numerical value of the differential pressure transmitter in real time, adjusts the flow acquisition mode according to the numerical value and selects a proper node for small signal cutting, so that the uniform-speed tubular flowmeter can accurately measure under the working condition of small flow; through multiple comparison, the differential pressure transmitter capable of minimizing the influence of temperature change is selected, so that the reliability and stability of the measurement result are guaranteed.
Drawings
FIG. 1 is a schematic structural diagram of the present application;
the system comprises a flow meter of a uniform velocity pipe, a first cut-off valve, a third cut-off valve, a first blow-down valve, a second cut-off valve, a balance valve, a fourth cut-off valve, a differential pressure transmitter, a second blow-down valve, a distributor, a PLC (programmable logic controller) and a user operation station, wherein the flow meter of the uniform velocity pipe is 1, the first cut-off valve is 2, the third cut-off valve is 3, the first blow-down valve is 4, the second cut-off valve is 5.
Detailed Description
The small flow metering device combined with the uniform velocity tube flowmeter shown in the figure 1 comprises a uniform velocity tube flowmeter 1 and a small flow metering device, wherein the small flow metering device comprises a first cut-off valve 2, a second cut-off valve 5, a third cut-off valve 3, a fourth cut-off valve 7, a balance valve 6, a first blow-off valve 4, a second blow-off valve 9, a differential pressure transmitter 8 and a remote control end; two exit ends of the uniform velocity tube flowmeter 1 are respectively provided with one end of a first cut-off valve 2 and one end of a second cut-off valve 5, the other end of the first cut-off valve 2 is connected with one end of a third cut-off valve 3, the other end of the second cut-off valve 5 is connected with one end of a fourth cut-off valve 7, and a balance valve 6 and a differential pressure transmitter 8 are arranged between the other ends of the third cut-off valve 3 and the fourth cut-off valve 7 and are simultaneously respectively connected with a first blow-off valve 4 and a second blow-off valve 9.
In the above device, in order to better implement control, the remote control end includes a distributor 10, a PLC controller 11 and a user operation station 12, the differential pressure transmitter 8 is connected to the distributor 10 of the remote control end through a cable, the distributor 10 is connected to the PLC controller 11 through a cable, the PLC controller 11 is connected to the user operation station 12 through a cable, and the model of the PLC controller 11 may be selected to be SLC-500.
The differential pressure of the physical quantity is measured by the uniform velocity tube flowmeter 1, the balance valve 6 is used for realizing that a positive pressure chamber and a negative pressure chamber of the differential pressure transmitter 8 have the same static pressure when the zero point of the differential pressure transmitter 8 is calibrated on line, namely, the zero point adjustment of the differential pressure transmitter 8 is realized, namely, the zero point adjustment of the differential pressure transmitter 8 refers to the zero point adjustment of the input pressure or the differential pressure when the input pressure or the differential pressure is 0 and the output is not 0, the zero point drift of the differential pressure transmitter 8 is eliminated, the first cut-off valve 2, the second cut-off valve 5, the third cut-off valve 3 and the fourth cut-off valve 7 are used for starting the differential pressure transmitter 8 or stopping the differential pressure transmitter 8 for operation, and the differential pressure of the physical quantity measured by the uniform velocity tube flowmeter 1 is converted into a 4; the first and second blowoff valves 4 and 9 discharge the measured material flowing down after the measurement.
Example 1
In the embodiment, through simulating field application conditions, the differential pressure transmitter 8 with excellent performance is screened out through test data, the model of the differential pressure transmitter 8 preferably adopts E + H PMD230 or EJA120A, and the specific screening mode is as follows:
by using the high-low temperature test box, a continuous high-low temperature change test is performed on the differential pressure transmitter 8 for energy metering, the influence range of the transmitter on temperature change is mastered, and an influence range relation table of the temperature change on the transmitter output is established. Firstly, the differential pressure transmitter 8 is correctly connected, after the power is supplied for 20 minutes, zero point and range adjustment is carried out, and after the adjustment is finished, the differential pressure transmitter 8 is horizontally placed in a high-low temperature test box (at the moment, the environmental temperature is 25.7 ℃). When the temperature of the digital display instrument indicates-10 ℃ and keeps 10 minutes, the output current value of the differential pressure transmitter 8 is recorded, the output current of the transmitter is recorded once when the temperature rises by 1 ℃, the current output is preferably stable, three differential pressure transmitters, namely E + H PMD230, EJA120A and STD930 are selected for comparison test in the test, and E + H PMD230 or EJA120A is preferably adopted according to the stability test result.
In addition, the stability test of the differential pressure transmitter 8 to the change of the power supply voltage is also carried out, and the three differential pressure transmitters can have stable current output within the normal voltage fluctuation range.
In combination with the above test options, the differential pressure transmitter is preferably E + H PMD230 or EJA 120A.
Example 2
On the basis of the differential pressure transmitter screened in the application embodiment 1, the embodiment also provides a small flow measurement method combined with a uniform velocity tube flow meter, which comprises the following steps:
(a) a differential pressure transmitter in the device transmits a measured differential pressure value to the PLC controller 11;
(b) the PLC controller 11 judges the value transmitted by the differential pressure transmitter;
(c) if the measured differential pressure value in the step (b) is more than 0.5% and within 1% of the range of the differential pressure transmitter 8, switching the flow acquisition mode to a linear output mode;
(d) if the measured differential pressure value in the step (b) is larger than 1% of the measuring range of the differential pressure transmitter, switching the flow acquisition mode to a square root output mode;
(e) if the measured differential pressure value in the step (b) is less than 0.5% of the measuring range of the differential pressure transmitter, cutting off a small signal;
(f) and calculating the flow according to the flow acquisition mode and the measured differential pressure value.
In general, a square root output mode is adopted, and according to the common knowledge, the relationship between a differential pressure value and a measured flow rate is as follows:
wherein, Δ Px is the measured differential pressure, Δ Pmax is the maximum range of the measured differential pressure, i.e. the range of the differential pressure transmitter, Qx is the measured flow, and Qmax is the maximum flow.
However, when the fluid flow rate is small, the output of the flow rate and the differential pressure value have a proportional linear relationship, so that the linear output mode is adopted.
Meters are used for metering and it is generally desirable to measure the minimum flow as small as possible, and for small flow measurements, it is desirable to have no cut if there is a way to do so without having to set a small signal cut. However, the influence of the temperature drift and the time drift of the differential pressure transmitter 8 on the zero point of the flowmeter tends to be bidirectional, and the transmission distortion of the differential pressure signal and the intrusion of the disturbance such as vibration are uncertain factors. In a flow metering system, the influence of the small signal cutting on the metering system is very important, and in order to ensure the metering to be accurate and reliable, the small signal cutting needs to be arranged and used. At present, the small signal cutting optimization of the differential pressure type flowmeter does not have a fixed formula, the small signal is not required to be cut, and how to take values between the size of a cutting value is an optimization concept, and the general principle is to select the cutting value to be smaller as far as possible on the premise of achieving the purpose. The cutting point can be reasonably adjusted according to the field environment temperature, vibration and interference conditions, and the cutting value is properly reduced.
At present, along with the popularization of a metering monitoring network in each large-scale industrial enterprise, flow acquisition signals are sent to a PLC system to complete the dynamic monitoring of each power energy medium analog quantity metering value. Using EJA120A type differential pressure transmitter 8 as an example: the zero drift value is 0.35% of the upper limit of the differential pressure through simulation test, and the zero drift value is 0.5% of the upper limit of the differential pressure actually measured in field operation. By combining two factors, the small signal cut-off point is optimized to be reduced to 0.5% of the recommended value of the range differential pressure from 1% of the range differential pressure, the small signal cut-off point is reasonably reduced, and the metering loss of the uniform-speed tubular flowmeter caused by the small signal cut-off is reduced.
Taking the site PLC controller 11 adopting SLC-500 series PLC of AB company in usa as an example, the specific configuration is as follows:
a processor: 1747-L552B
10-groove frame: 1746-A10
Analog quantity input module: 1746-NI8
The analog input module 1746-NI8 has an input signal range of 4-20 mA.DC, corresponding to data formats 3277-16384. The acquisition of the metering value of each medium analog quantity is accurately finished. The small signal cut-off output returns to zero 4ma.dc (3277) when the differential pressure transmitter output is less than 0.5% (3341) input point of the span pressure, the differential pressure transmitter output is less than 1% (3408) input point of the span pressure and switches to linear output, and the differential pressure transmitter output is greater than 1% (3408) input point of the span pressure and switches from linear smoothing to square root output. The PLC controller 11 may send data to the user operating station 12 through which the operator may directly observe the measured data and the current flow collection mode.
Claims (5)
1. A small flow meter device combined with a uniform velocity tube flow meter, comprising a uniform velocity tube flow meter (1) and a small flow meter device, characterized in that: the small flow metering device comprises a first cut-off valve (2), a second cut-off valve (5), a third cut-off valve (3), a fourth cut-off valve (7), a balance valve (6), a first blow-down valve (4), a second blow-down valve (9), a differential pressure transmitter (8) and a remote control end;
two outlet ends of the uniform-speed pipe flowmeter (1) are respectively connected with one end of a first cut-off valve (2) and one end of a second cut-off valve (5), the other end of the first cut-off valve (2) is connected with one end of a third cut-off valve (3) through a pressure guide pipeline, the other end of the second cut-off valve (5) is connected with one end of a fourth cut-off valve (7) through a pressure guide pipeline, a balance valve (6) and a differential pressure transmitter (8) are installed between the other end of the third cut-off valve (3) and the other end of the fourth cut-off valve (7) in parallel, and simultaneously, the balance valve and the second blow-off valve (4) are respectively connected through pressure guide pipelines; the remote control end is connected to a differential pressure transmitter (8) through a cable.
2. A small flow meter device in combination with a homogenizer according to claim 1, wherein: the differential pressure transmitter (8) is of the type E + H PMD230 or EJA 120A.
3. A small flow meter device in combination with a homogenizer according to claim 1, wherein: the remote control end comprises a distributor (10), a PLC (programmable logic controller) (11) and a user operation station (12), the differential pressure transmitter (8) is connected with the distributor (10) of the remote control end through a cable, the distributor (10) is connected with the PLC (11) through a cable, and the PLC (11) is connected to the user operation station (12) through a cable.
4. A small flow meter device in combination with a homogenizer according to claim 3, wherein: the PLC controller (11) is SLC-500 in model.
5. A small flow metering method in combination with a uniform velocity tube flow meter, applied to a small flow metering device in combination with a uniform velocity tube flow meter according to any one of claims 1 to 4, comprising the steps of:
(a) a differential pressure transmitter (8) in the device transmits a measured differential pressure value to a PLC controller (11);
(b) the PLC (11) judges the value transmitted by the differential pressure transmitter (8);
(c) if the measured differential pressure value in the step (b) is more than 0.5% and within 1% of the range of the differential pressure transmitter, switching the flow acquisition mode to a linear output mode;
(d) if the measured differential pressure value in the step (b) is larger than 1% of the measuring range of the differential pressure transmitter, switching the flow acquisition mode to a square root output mode;
(e) if the measured differential pressure value in the step (b) is less than 0.5% of the measuring range of the differential pressure transmitter, cutting off a small signal;
(f) and calculating the flow according to the flow acquisition mode and the measured differential pressure value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011039043.2A CN112378464B (en) | 2020-09-28 | 2020-09-28 | Small flow metering device combined with uniform speed pipe flowmeter and method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011039043.2A CN112378464B (en) | 2020-09-28 | 2020-09-28 | Small flow metering device combined with uniform speed pipe flowmeter and method thereof |
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| Publication Number | Publication Date |
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| CN112378464A true CN112378464A (en) | 2021-02-19 |
| CN112378464B CN112378464B (en) | 2024-07-02 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN202852037U (en) * | 2012-09-25 | 2013-04-03 | 宝山钢铁股份有限公司 | Work valve for differential pressure transmitter |
| CN202974349U (en) * | 2012-06-25 | 2013-06-05 | 上海梅山钢铁股份有限公司 | Device capable of measuring flows of mediums of different densities |
| CN103185614A (en) * | 2013-02-13 | 2013-07-03 | 乌光 | Differential pressure flow transmitter with multiple ranges and automatic range switching function |
| CN103292848A (en) * | 2013-05-13 | 2013-09-11 | 华北电力大学 | Differential-pressure flow measurement device for fluids in circular-section pipes and measuring method |
| CN203964965U (en) * | 2014-05-29 | 2014-11-26 | 上海梅山钢铁股份有限公司 | A kind of wide flow measurement device |
| CN205748496U (en) * | 2016-07-06 | 2016-11-30 | 江小飞 | A kind of wide-range V-arrangement taper flow meter |
-
2020
- 2020-09-28 CN CN202011039043.2A patent/CN112378464B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202974349U (en) * | 2012-06-25 | 2013-06-05 | 上海梅山钢铁股份有限公司 | Device capable of measuring flows of mediums of different densities |
| CN202852037U (en) * | 2012-09-25 | 2013-04-03 | 宝山钢铁股份有限公司 | Work valve for differential pressure transmitter |
| CN103185614A (en) * | 2013-02-13 | 2013-07-03 | 乌光 | Differential pressure flow transmitter with multiple ranges and automatic range switching function |
| CN103292848A (en) * | 2013-05-13 | 2013-09-11 | 华北电力大学 | Differential-pressure flow measurement device for fluids in circular-section pipes and measuring method |
| CN203964965U (en) * | 2014-05-29 | 2014-11-26 | 上海梅山钢铁股份有限公司 | A kind of wide flow measurement device |
| CN205748496U (en) * | 2016-07-06 | 2016-11-30 | 江小飞 | A kind of wide-range V-arrangement taper flow meter |
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