CN103697974A - Verifying device and verifying method of liquid metal flowmeter - Google Patents

Abstract

The invention relates to a verification or calibration device and method for measuring flow meter equipment. In order to solve the problems of the existing liquid metal flowmeter calibration device and calibration method, such as low calibration accuracy, narrow calibration range, and low safety, the present invention provides a liquid metal flowmeter calibration device and calibration method. test method. The device includes a storage tank, a heater, an electromagnetic pump, a main measuring cylinder, an auxiliary measuring cylinder, a preheater, a liquid metal flowmeter interface A, a liquid metal flowmeter interface B, and a steam trap. A calibration method using the liquid metal flowmeter calibration device described above, the method uses a segmented calibration mode to calibrate different ranges of the liquid metal flowmeter. The liquid metal flowmeter calibration device of the present invention belongs to the original standard device, which can realize the actual flow calibration of the liquid metal flowmeter transmission flow value or test accuracy, high calibration accuracy, large calibration range, and high safety. The cost is low and has good applicability.

Description

Calibration device and calibration method for a liquid metal flowmeter

technical field

The invention relates to a verification or correction device and method for instrument equipment used to measure flow, in particular to a liquid metal flowmeter verification device and verification method.

Background technique

Flow standard devices can be divided into two categories: original standard devices and transfer standard devices according to the value traceability system. The original standard device uses the basic quantity length (derived as volume) or mass and time to comprehensively derive the flow rate. Compared with the transfer standard device that uses standard flowmeters for value transfer, the original standard device has high precision, complex system composition, and large investment. Usually, flow measurement research institutes and large-scale flow meter factories mainly focus on setting original standard devices.

For liquid metal flowmeters (such as: permanent magnet type, electromagnetic type, differential pressure type, etc.), the operating medium includes lithium, sodium, sodium potassium alloy, lead, lead bismuth alloy, lithium lead alloy, mercury, etc. Liquid metal materials, and the working temperature of these liquid metal materials often exceeds 600°C, will oxidize when exposed to air, and some will explode when exposed to water. Due to the existence of these reasons, there is a lack of suitable liquid metal flow standard devices in the prior art, so the flow meter factory usually only gives the flow rate based on theoretical derivation when the liquid metal flowmeter leaves the factory, such as through the magnetic flux density and working fluid. The flow rate of the permanent magnet flowmeter is derived from the relational formula of the physical properties, and its accuracy is usually low (greater than 5%). Generally, it can only be used as a monitoring instrument, and it is impossible to realize the flow value or test accuracy of the liquid metal flowmeter. Real flow verification.

At present, since the measurement departments at all levels of the country have not established liquid metal flowmeter calibration devices, the calibration of liquid metal flowmeters can only be completed by the user itself. For actual flow calibration, it is necessary to design a suitable calibration device and calibration method for liquid metal flowmeters.

Contents of the invention

In order to solve the problems of the existing liquid metal flowmeter calibration device and calibration method, such as low calibration accuracy, narrow calibration range, and low safety, the present invention provides a liquid metal flowmeter calibration device and calibration method. test method.

A liquid metal flowmeter calibration device, comprising a storage tank, a heater, an electromagnetic pump, a main measuring cylinder, an auxiliary measuring cylinder, a preheater, a liquid metal flowmeter interface A, a liquid metal flowmeter interface B, and a steam trap;

In the vertical direction, the storage tank is set at the lowest point, the bottom of the auxiliary graduated cylinder is higher than the top of the storage tank, and the bottom of the main graduated cylinder is higher than the top of the auxiliary graduated cylinder;

Both the main measuring cylinder and the auxiliary measuring cylinder are airtight containers, all of which are provided with an inlet, a bottom outlet and an overflow port, and the liquid level anti-fluctuation measures are adopted inside to prevent the liquid metal from fluctuating when the liquid metal is contained;

Both the liquid metal flowmeter interface A and the liquid metal flowmeter interface B can connect the pipeline when the liquid metal flowmeter is not connected, and can connect the liquid metal flowmeter in series when the liquid metal flowmeter is connected. the interface in the road;

The preheater is distributed in all positions where the liquid metal may exist in the liquid metal flowmeter calibration device during the entire calibration process;

The inlet of the heater is connected to the storage tank through a pipeline with a valve V1, and the end of the pipeline connected to the storage tank extends into the storage tank; the outlet of the heater is connected to the inlet of the electromagnetic pump through a pipeline;

The outlet end of the electromagnetic pump is connected to one end of the interface A of the liquid metal flowmeter through a pipeline, and the other end of the interface A of the liquid metal flowmeter is respectively connected to the inlet of the main measuring cylinder and the pipeline with the valve V2 through the pipeline with the valve V3 and the pipeline with the valve V2. One end of the interface B of the liquid metal flowmeter is connected, and this end of the interface B of the liquid metal flowmeter is also connected to the outlet at the bottom of the main measuring cylinder through a pipeline with a valve V4;

The other end of the liquid metal flowmeter interface B is connected to the inlet of the auxiliary graduated cylinder through a pipeline with a valve V5;

The overflow port of the main measuring cylinder is connected with the overflow port of the auxiliary measuring cylinder through a pipeline, and the pipeline connecting the overflow opening of the main measuring cylinder and the overflow opening of the auxiliary measuring cylinder is also connected with the storage tank through a pipeline with a valve V8;

The outlet at the bottom of the auxiliary graduated cylinder is connected to the storage tank and the heater inlet respectively through a pipeline with a valve V6 and a pipeline with a valve V7;

The top of the storage tank is also connected to one end of the steam trap through a pipeline, and the other end of the steam trap is connected to a gas inlet and outlet controlled by a valve;

All pipelines arranged horizontally adopt an inclination angle of 2 to 6 degrees to facilitate the discharge of liquid metal back to the storage tank.

The valves V1, V4, V6, V7, and V8 of the liquid metal flowmeter calibration device are preferably pneumatic shut-off valves.

The valve V2 of the liquid metal flowmeter calibration device is preferably an electric cut-off valve.

The valves V3 and V5 of the liquid metal flowmeter calibration device are preferably electric regulating valves.

The storage tank, heater, electromagnetic pump, main measuring cylinder, auxiliary measuring cylinder, all pipelines and all valves of the liquid metal flowmeter calibration device are preferably made of stainless steel to be compatible with liquid metal.

A calibration method using the above-mentioned liquid metal flowmeter calibration device, the method uses a segmented calibration mode to calibrate different ranges of the liquid metal flowmeter, specifically as follows:

(1) The measuring range below 1.0m ³ /h shall be calibrated by the calibration method of gravity-driven constant pressure head standard volume method, and the steps include ⑴-⑺;

⑴ Install the liquid metal flowmeter to be calibrated on the liquid metal flowmeter interface B, connect the liquid metal flowmeter to be calibrated in series in the pipeline, keep the pipeline at the interface A of the liquid metal flowmeter connected, and then check the entire device Air tightness check;

(2) Turn on the heater and preheater, and heat the liquid metal flowmeter calibration device to a temperature higher than the melting point of the liquid metal used in all positions where the liquid metal may exist during the entire calibration process;

(3) Close the valves V6, V7, V8 and V2, open the valves V1, V3, V4, V5 and the gas inlet and outlet valves, press the liquid metal into the electromagnetic pump by feeding inert gas into the gas inlet and outlet, turn on the electromagnetic pump, and open the valves V6 and V8 , establish a cycle through the valve V3, the main measuring cylinder, the valve V4, the liquid metal flowmeter to be verified, the valve V5, the auxiliary measuring cylinder, and the valve V6, and make the flow rate of the liquid metal at the outlet of the electromagnetic pump greater than 2m ³ /h;

(4) Adjust the heater and preheater so that the temperature of the liquid metal in the calibration device of the liquid metal flowmeter is kept constant at the temperature required for calibration throughout the calibration process;

(5) Gradually close the valve V5 to make the main measuring cylinder overflow. At this time, the gravity of the liquid metal in the upstream of the liquid metal flowmeter to be calibrated will generate a stable driving pressure head. Continue to close the valve V5 to make the liquid metal passing through the valve V5 The flow is equal to the required verification flow value;

⑹Close the valve V6, the liquid level of the liquid metal in the auxiliary measuring cylinder will gradually rise, and record the volume increment of the liquid metal in the auxiliary measuring cylinder and the time used to obtain the liquid metal flow rate, that is, the flow rate of the liquid metal flowmeter to be verified, and then open Valve V6, to discharge the liquid metal in the auxiliary graduated cylinder;

(7) Repeat steps (4) to (6) one or more times, and take the average value;

(2) The measuring range above 1.5m ³ /h is calibrated by the standard volume method of the electromagnetic pump driven constant pressure head, and the steps include ⑻-⒀;

⑻Install the liquid metal flowmeter to be calibrated on the liquid metal flowmeter interface A, connect the liquid metal flowmeter to be calibrated in series in the pipeline, keep the pipeline at the liquid metal flowmeter interface B connected, and then carry out the whole device Air tightness check;

⑼ Turn on the heater and preheater, and heat the liquid metal flowmeter calibration device to a temperature higher than the melting point of the liquid metal used in all positions where the liquid metal may exist during the entire calibration process;

⑽ Close the valves V6, V7, V8 and V2, open the valves V1, V3, V4, V5 and the gas inlet and outlet valves, press the liquid metal into the electromagnetic pump by feeding inert gas into the gas inlet and outlet, turn on the electromagnetic pump, and open the valves V6 and V8 , to establish a cycle of sequentially passing through the liquid metal flowmeter to be verified, valve V3, main measuring cylinder, valve V4, valve V5, auxiliary measuring cylinder, and valve V6;

⑾Adjust the liquid metal flow at the outlet of the electromagnetic pump to the required calibration flow value, adjust the heater and preheater, so that the temperature of the liquid metal in the calibration device of the liquid metal flowmeter is kept at a constant temperature during the calibration process. required temperature;

⑿Close the valve V4, the liquid level of the liquid metal in the main measuring cylinder will gradually rise, record the volume increment of the liquid metal in the main measuring cylinder and the time it takes, and obtain the flow rate of the liquid metal, that is, the flow rate of the liquid metal flowmeter to be calibrated, and then open Valve V4, to discharge the liquid metal in the main measuring cylinder;

⒀Repeat steps ⑾～⑿ one or more times, and take the average value;

(3) When the required calibration range is within the range of 1.0-1.5m ³ /h, one of the two calibration methods (1) or (2) shall be selected as the calibration method.

When the liquid metal flowmeter needs to be fully calibrated, the required calibration data of the liquid metal flowmeter to be calibrated can be obtained by changing the temperature required for the corresponding calibration and the required calibration flow value in this calibration method .

The liquid metal flowmeter calibration device of the present invention adopts different calibration methods for different ranges, among which, the small range adopts the gravity-driven constant pressure head standard volume method for calibration, and the large range uses the electromagnetic pump to drive the constant pressure head standard volume method. This design enables the calibration device to have a very large calibration range, and not only ensures the calibration accuracy of a small range, but also ensures that the calibration device has a lower overall height when a large range is used. Since the height of the liquid metal system is directly proportional to the hazard after leakage, the reduction of the total height significantly improves the safety of the calibration device, so this design also takes into account the accuracy and safety of the calibration device.

At the same time, the whole structure design of the liquid metal flowmeter verification device of the present invention is reasonable, the scale of the device is effectively reduced, and the safety and economy of the verification device can be taken into account. The vapor trap used is used to prevent liquid metal vapor from accumulating in the liquid metal flowmeter calibration device, so as not to affect the calibration.

The calibration device of the liquid metal flowmeter of the invention belongs to the original standard device, and can realize the actual flow calibration of the transmission flow value or test accuracy of the liquid metal flowmeter. Using the liquid metal flowmeter calibration device and calibration method of the present invention to calibrate the liquid metal flowmeter, the calibration accuracy is high, and the calibration range is better than 1%, and the standard volume of the constant pressure head driven by gravity is adopted. The calibration method is better than 0.5%; the calibration range is large, and the ratio of the maximum calibration range to the minimum calibration range is greater than 150; the calibration device has high safety, low cost, and good applicability.

Description of drawings

Fig. 1 schematic diagram of liquid metal flowmeter calibration device of the present invention

Reference signs: 1. Storage tank, 2. Valve V1, 3. Heater, 4. Electromagnetic pump, 5. Liquid metal flowmeter interface A, 6. Valve V2, 7. Valve V3, 8. Main measuring barrel, 9 .Valve V4, 10. Liquid metal flowmeter interface B, 11. Valve V5, 12. Auxiliary measuring cylinder, 13. Valve V6, 14. Valve V7, 15. Valve V8, 16. Steam trap, 17. Gas inlet and outlet

Detailed ways

The implementation of the present invention will be further described below in combination with specific examples.

Example

The liquid metal flowmeter calibration device and calibration method of the present invention are used to calibrate a permanent magnet liquid metal flowmeter. The liquid metal used is sodium, and the calibration range is 0.2-2.0m ³ /h. The required temperatures are 200°C, 300°C, and 400°C, and the required calibration flow values are 0.2m ³ /h, 0.5m 3 /h, ^{0.8m 3} /h, 1.1m ³ /h ^, 1.4m ^{3 /} h h, 1.7m ³ /h, 2.0m ³ /h.

Among them: the range below 1.2m ³ /h adopts the calibration method of gravity-driven constant pressure head standard volume method for calibration, and repeats steps ⑷～⑹ once; the range above 1.2m ³ /h adopts the standard volume method of electromagnetic pump driven constant pressure head Verify by the verification method, repeat steps ⑾～⑿ once.

The verification results show that the liquid metal flowmeter verification device and verification method of the present invention have high verification accuracy, good data consistency, safe and applicable verification device, stable performance and convenient operation.

Claims (7)

1. a liquid metal flow gauge checking apparatus, is characterized in that: this device comprises storage tank, well heater, electromagnetic pump, main graduated cylinder, secondary graduated cylinder, primary heater, liquid metal flowmeter interface A, liquid metal flowmeter interface B, vapor trap;

In vertical direction, storage tank is arranged on minimum point, and secondary graduated cylinder bottom is higher than storage tank top, and main graduated cylinder bottom is higher than secondary graduated cylinder top;

Described main graduated cylinder and secondary graduated cylinder are closed container, are equipped with entrance, outlet at bottom and overflow vent, and inside all adopts the anti-fluctuation measure of liquid level, the liquid fluctuating of liquid metal while preventing from holding liquid metal;

Described liquid metal flowmeter interface A and liquid metal flowmeter interface B are not when liquid metal flowmeter accesses and can make pipeline connection, and when liquid metal flowmeter accesses, can make liquid metal flowmeter be connected on the interface in pipeline;

Described primary heater is distributed in all positions that this liquid metal flow gauge checking apparatus liquid metal in whole checking procedure may exist;

Described calorifier inlets end is connected with storage tank by the pipeline with valve V1, and storage tank inside is stretched in one end that this pipeline is connected with storage tank; Heater outlet end is connected with electromagnetic pump inlet end by pipeline;

Electromagnetic pump endpiece is connected with one end of liquid metal flowmeter interface A by pipeline, the other end of liquid metal flowmeter interface A is connected with one end of main graduated cylinder entrance and liquid metal flowmeter interface B respectively by the pipeline with valve V3 and with the pipeline of valve V2, and this end of liquid metal flowmeter interface B is also connected with main graduated cylinder outlet at bottom by the pipeline with valve V4;

The other end of liquid metal flowmeter interface B is connected with secondary graduated cylinder entrance by the pipeline with valve V5;

Main graduated cylinder overflow vent is connected by pipeline with secondary graduated cylinder overflow vent, connects main graduated cylinder overflow vent and also by the pipeline with valve V8, is connected with storage tank with the pipeline of secondary graduated cylinder overflow vent;

Secondary graduated cylinder outlet at bottom is connected with storage tank and calorifier inlets end respectively by the pipeline with valve V6 and with the pipeline of valve V7;

Storage tank top is also connected with one end of vapor trap by pipeline, and the other end of vapor trap is connected with the gas inlet-outlet of being controlled by valve;

All pipelines of lateral arrangement all adopt the angle of inclination of 2～6 degree to flow back to storage tank to be conducive to liquid metal.

2. liquid metal flow gauge checking apparatus as claimed in claim 1, is characterized in that: valve V1, the V4 of described liquid metal flow gauge checking apparatus, V6, V7, V8 are pneumatic stopping valve.

3. liquid metal flow gauge checking apparatus as claimed in claim 1, is characterized in that: the valve V2 of described liquid metal flow gauge checking apparatus is electric check valve.

4. liquid metal flow gauge checking apparatus as claimed in claim 1, is characterized in that: valve V3, the V5 of described liquid metal flow gauge checking apparatus is electric control valve.

5. liquid metal flow gauge checking apparatus as claimed in claim 1, is characterized in that: the storage tank of described liquid metal flow gauge checking apparatus, well heater, electromagnetic pump, main graduated cylinder, secondary graduated cylinder, all pipelines and valvular material all adopt stainless steel.

6. a method of calibration for liquid metal flow gauge checking apparatus as claimed in claim 1, is characterized in that the method adopts the different ranges of segmentation checking mode liquid towards metal flow meter to carry out verification, specific as follows:

(1) 1.0m ³the following range of/h adopts the verification mode of the accurate volumetric method of segregation drive level pressure leader to carry out verification, and (1) its step comprise-(7);

(1) liquid metal flowmeter to be verified is arranged on to liquid metal flowmeter interface B, liquid metal flowmeter to be verified is connected in pipeline, the pipeline at liquid metal flowmeter interface A place keeps being communicated with, and then whole device is carried out to airtight test;

(2) heater and primary heater, be heated above the temperature of this liquid metal flow gauge checking apparatus all positions that liquid metal may exist in whole checking procedure the fusing point of adopted liquid metal;

(3) valve-off V6, V7, V8 and V2, Open valve V1, V3, V4, V5 and gas inlet-outlet valve, by passing into inert gas to gas inlet-outlet, liquid metal is pressed into electromagnetic pump, open electromagnetic pump, Open valve V6 and V8, set up successively the circulation through valve V3, main graduated cylinder, valve V4, liquid metal flowmeter to be verified, valve V5, secondary graduated cylinder, valve V6, and make the liquid metal flow of electromagnetic pump outlet be greater than 2m ³/ h;

(4) adjust well heater and primary heater, make temperature constant temperature in whole checking procedure of liquid metal in this liquid metal flow gauge checking apparatus temperature required in verification;

(5) close gradually minor valve V5, make main graduated cylinder produce overflow, now, in liquid metal flowmeter to be verified upstream, by liquid metal gravity, produce stable drive ram, continue to close minor valve V5, make to equal required checking flow value by the liquid metal flow of valve V5;

(6) valve-off V6, the liquid level of liquid metal in secondary graduated cylinder raises gradually, liquid metal dilatation and time used in the secondary graduated cylinder of minute segment record, obtain liquid metal flow, be liquid metal flowmeter flow to be verified, then open valve V6, discharge the liquid metal in secondary graduated cylinder;

Repeating step (4)～(6) one or many, average;

(2) 1.5m ³the above range of/h adopts electromagnetic pump to drive the verification mode of the accurate volumetric method of level pressure leader to carry out verification, and (8) its step comprise-(13);

(8) liquid metal flowmeter to be verified is arranged on to liquid metal flowmeter interface A, liquid metal flowmeter to be verified is connected in pipeline, the pipeline at liquid metal flowmeter interface B place keeps being communicated with, and then whole device is carried out to airtight test;

(9) heater and primary heater, be heated above the temperature of this liquid metal flow gauge checking apparatus all positions that liquid metal may exist in whole checking procedure the fusing point of adopted liquid metal;

(10) valve-off V6, V7, V8 and V2, Open valve V1, V3, V4, V5 and gas inlet-outlet valve, by passing into inert gas to gas inlet-outlet, liquid metal is pressed into electromagnetic pump, open electromagnetic pump, Open valve V6 and V8, set up successively the circulation through liquid metal flowmeter to be verified, valve V3, main graduated cylinder, valve V4, valve V5, secondary graduated cylinder, valve V6;

(11) the liquid metal flow of electromagnetic pump outlet is adjusted to required checking flow value, adjusts well heater and primary heater, make temperature constant temperature in whole checking procedure of liquid metal in this liquid metal flow gauge checking apparatus temperature required in verification;

(12) valve-off V4, the liquid level of liquid metal in main graduated cylinder raises gradually, liquid metal dilatation and time used in minute main graduated cylinder of segment record, obtain liquid metal flow, be liquid metal flowmeter flow to be verified, then open valve V4, discharge the liquid metal in main graduated cylinder;

Repeating step (11)～(12) one or many, average;

(3) when the range of required verification is at 1.0～1.5m ³in the time of within the scope of/h, verification mode is selected a kind of in (one) or (two) two kinds of verification modes.

7. the method for calibration of liquid metal flow gauge checking apparatus as claimed in claim 6, it is characterized in that: when needs liquid towards metal flow meter carries out comprehensive verification, by changing the temperature required and required checking flow value of corresponding verification in this method of calibration, obtain required liquid metal flowmeter checking data to be verified.

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