CN206321315U - The density calibration system of mass flowmenter - Google Patents

Abstract

The utility model provides a density calibration system for a mass flowmeter, which comprises: a calibration solution device, which is used to provide a variety of calibration solutions with different densities; a solution pump, which is used to provide power to flow the calibration solution at a certain pressure In the calibration pipeline; a standard gauge and a plurality of mass flowmeters to be tested are evenly installed on the calibration pipeline along the output end of the solution pump; the standard gauge is used to calibrate the density of the solution in the calibration pipeline; the computer, respectively Connect a plurality of mass flowmeters to be tested, standard meters and switches; it is used to control the switches to switch the calibration solution of different media to calibrate the density of the mass flowmeter, and write the calculated density calibration coefficient according to the density calibration mathematical model Corresponding mass flow meter. Using computer calibration solutions in different media, the density of mass flowmeters is measured multiple times, and the density of mass flowmeters to be tested is calculated through the density calibration mathematical model, which improves the efficiency and accuracy of calibration.

Description

Density Calibration System for Mass Flow Meter

technical field

The utility model belongs to the technical field of instrument correction, in particular to a density calibration system of a mass flow meter.

Background technique

Mass flowmeter, that is, Coriolis force mass flowmeter, is a flow measurement instrument developed and designed using the principle of fluid mechanics. It is mainly used to measure the mass flow and density of gas and liquid, as well as the volume flow, total mass and total volume derived from mass flow and density, etc. Mass flowmeters can measure a wide range of fluids, including various liquids with high viscosity liquids, slurries containing solids, liquids containing a small amount of uniformly distributed gas, and gases with sufficient density, such as high-pressure gases. Overall, it is capable of measuring mass flow, density and temperature of liquids, suspensions, emulsions and gases.

For the establishment and realization of the mass flow mathematical model of the mass flowmeter, as well as the calibration process in production, there are a lot of explanations in many papers, journals and patents at home and abroad, and there are countless parameter methods available, but in terms of density There are not many literatures that can be referred to on the mathematical model, calibration method and related calibration equipment. For mass flowmeters, the first parameter is mass flow, and the parameter related to it and corresponding to the proportional output is the phase difference of the output sinusoidal signal detected on both sides of the sensor measuring tube; the second parameter is density, which is related to the inherent mechanical properties of the sensor itself. Frequency dependent, only the existence of the second parameter density, there will be engineering parameters such as volume flow and total volume derived from mass flow and density. Therefore, in many fields such as petroleum, petrochemical, papermaking, food, pharmaceuticals, etc., mass flow rate, density, volume flow rate and other parameters of various conventional fluids, unconventional fluids, slurry, liquefied gas and compressed natural gas will be used. flow meter. Therefore, for mass flowmeter manufacturers, it is very important to improve the design, production and processing technology of mass flowmeter sensors, as well as mass flow calibration devices and density calibration devices.

As shown in Figure 1, it is a schematic structural diagram of an existing Coriolis force mass flowmeter density calibration system, wherein, the low-pressure cylinder is used to store low-pressure dry air less than 5 atmospheres; the air valve is used for The switch used to control the low-pressure gas in the low-pressure cylinder entering the calibration pipeline; the calibration solution container, which is used to hold the medium solution for density calibration, and the calibration solution is usually proportioned in the container; the solution inlet port, which is the density calibration solution. The starting end is designed as a funnel, which is convenient for the calibration solution to flow into the sensor measurement pipeline through this port without side leakage; the calibration pipeline is used to calibrate the channel through which the medium solution flows; the mass flowmeter is the mass to be calibrated for density Flowmeter; fixed base frame, which is a cement pile, used to fix and clamp the mass flowmeter to be calibrated; the solution outlet port, which is the terminal of the density calibration pipe, is designed as a funnel, which is convenient for the calibration solution to flow into the meter through this port In the container of volume; switch, which is used to control the amount of density calibration solution flowing into the volume container; volume container, which is used to hold the medium solution for density calibration, and simultaneously measure the volume of density calibration solution; electronic scale, which is used The mass of the density calibration solution in the metered volume.

The flow chart of the calibration method of the density calibration system of the mass flowmeter in Fig. 1 is described in detail as follows:

Step 1, put the mass flowmeter density calibration system in a constant temperature closed room at 25°C, and at the same time, make the gas valve and the switch at the end of the calibration pipeline in the closed state;

Step 2, install the mass flowmeter to be tested on the calibration pipeline as shown in Figure 1, and ensure that the calibration pipeline and the mounting flange of the mass flowmeter are in a sealed state, that is, there is no leakage, and at the same time, the mass flow rate is guaranteed The meter housing is perpendicular to the ground;

Step 3, power on the mass flowmeter to be calibrated for density, and place more than 5 calibration solutions of different densities (medium solution 1, medium solution 2, medium solution 3...) in the secret room for density calibration In the middle, keep working in this state for about 180 minutes, the purpose is to make the temperature of the entire system of mass flowmeter density calibration and the temperature of the density calibration solution be the same as or infinitely close to the temperature of the closed room;

Step 4, collect the empty pipe frequency of the output sensor on the mass flowmeter converter to be calibrated on the currently calibrated pipeline in the current 25°C constant temperature closed chamber;

Step 5, open the sealing cover above the solution inlet, slowly pour the density calibration medium solution 1 into the solution inlet through the calibration solution container device, observe the change of the liquid level at the solution outlet, when the liquid level is close to the top of the solution outlet, stop Continue to pour density calibration medium solution 1 into the solution inlet;

Step 6, delaying for 2 minutes, until the density calibration medium solution 1 is in a stable state in the calibration pipeline device, collect the frequency value of the output sensor on the current mass flowmeter converter;

Step 7, slowly adjust the switch at the end of the calibration pipeline, discharge the density calibration medium solution 1 in the pipeline into the container at the upper end of the electronic scale, so that the discharge volume of the density calibration medium solution 1 reaches the position of the 1000ml scale of the container;

Step 8, obtain the mass indication of 1000ml of density calibration medium solution 1 measured on the electronic scale, and pour the density calibration medium solution 1 back into the original solution device, and replace it with a dry container of the same capacity and place it on the electronic scale;

Step 9, press the sealing cap above the solution inlet end tightly to the solution inlet end, slowly adjust the air valve until the density calibration medium solution 1 in the calibration pipeline is driven out of the calibration pipeline, and then close the air valve;

Step 10, repeat steps 5 to 9 to complete the calibration process of other density calibration medium solutions (medium solution 2, medium solution 3...);

Step 11, calculate the density coefficient of the mass flowmeter to be density calibrated according to the density calibration record data, and write the coefficient into the EEPROM of the mass flowmeter converter through key operation;

Step 12, performing density accuracy detection and repeatability detection of the mass flowmeter;

Step 13, open the sealing cover above the solution inlet and the switch at the end of the calibration pipe, slowly pour the density calibration medium solution 1 through the calibration solution vessel device into the solution inlet, observe the change of the liquid level in the container, when the liquid level scale When it is close to 1000ml, turn off the switch at the end of the calibration pipeline, and continue to pour an appropriate amount of density calibration medium solution 1 into the solution inlet;

Step 14, fine-tune the opening of the switch at the end of the calibration pipeline until the drop value of the density calibration medium solution 1 reaches the 1000ml scale position in the container, collect the current output density value of the mass flowmeter converter and the electronic scale to measure the density calibration medium solution 1 the total mass of

Step 15, press the sealing cap above the solution inlet end tightly to the solution inlet end, fine-tune the air valve until the density calibration medium solution 1 in the calibration pipeline is driven out of the calibration pipeline, and then close the air valve;

Step 16, repeating steps 13 to 15 to complete the density verification process of other selected density calibration medium solutions;

Step 17, calculating the density output accuracy and repeatability of the mass flow meter.

In the existing Coriolis force mass flowmeter density calibration system, it can only accommodate the density calibration and detection of 3 mass flowmeters at most, which greatly reduces the calibration efficiency of mass flowmeters; at the same time, in the whole calibration and detection In the process, manual participation is required, and the density of the calibration solution is measured with a small container as the volume. The electronic scale measures the quality of the calibration solution, and the standard value of the density of the calibration solution is determined by calculation. However, these factors will bring a certain degree of measurement calibration error, which reduces the accuracy of the entire mass flowmeter density calibration system.

Utility model content

In view of the above-mentioned shortcomings of the prior art, the purpose of this utility model is to provide a density calibration system for mass flowmeters, which is used to solve the problem of manual operation of mass flowmeters in the prior art during density calibration, which causes the entire mass flowmeter to Low efficiency and low precision of density calibration.

In order to achieve the above purpose and other related purposes, the utility model provides a density calibration system for a mass flow meter, including:

Calibration solution device, which is used to provide a variety of calibration solutions with different densities; solution pump, which is used to provide power to flow the calibration solution in the calibration pipeline at a certain pressure; The output end of the solution pump is evenly installed on the calibration pipeline; the standard meter is used to calibrate the density of the solution in the calibration pipeline; the computer is connected to a plurality of mass flow meters, standard meters and switches to be measured respectively; it is used for Control the switch to switch the calibration solutions of different media to calibrate the density of the mass flowmeter, and write the calculated density calibration coefficient into the corresponding mass flowmeter according to the density calibration mathematical model.

As mentioned above, the density calibration system of the mass flowmeter of the present invention has the following beneficial effects:

By replacing the original manually operated density calibration system with a computer-controlled density calibration system, compared with the original density calibration system, the number of each calibration is changed from three to ten, which improves the efficiency of product calibration; adopts computer The control switch switches the calibration solutions in different media, and the density of the mass flowmeter is measured multiple times under each calibration solution. There is no need for human participation in the calibration process. The density of the mass flowmeter to be tested is calculated through the density calibration mathematical model, which not only eliminates the The calibration error of the traditional mass volume method also greatly improves the accuracy of the density calibration of the mass flowmeter; at the same time, a constant pressure and constant flow tank is introduced into the density calibration system, which eliminates the calibration solution produced by the solution pump when it is working. The problem of flow and air bubbles essentially improves the calibration accuracy of the mass flow meter.

Description of drawings

Fig. 1 shows the structural representation of the existing Coriolis force mass flowmeter calibration system provided for the utility model;

Fig. 2 shows the structural diagram of a density calibration system of a mass flowmeter provided by the utility model;

Fig. 3 shows a structure diagram of an embodiment of a mass flow meter density calibration system provided by the utility model.

detailed description

The implementation of the present utility model is illustrated by specific specific examples below, and those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification.

Please refer to Figure 2 to Figure 3. It should be noted that the structures, proportions, sizes, etc. shown in the drawings attached to this specification are only used to match the content disclosed in the specification, for those who are familiar with this technology to understand and read, and are not used to limit the implementation of the utility model Therefore, it has no technical substantive meaning. Any modification of structure, change of proportional relationship or adjustment of size shall still fall within the scope of The technical content disclosed by the utility model must be within the scope covered. At the same time, terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit this specification. The practicable range of the utility model, and the change or adjustment of its relative relationship, without any substantial change in the technical content, shall also be regarded as the practicable scope of the utility model.

Please refer to Figure 2, the utility model provides a structural diagram of a density calibration system for a mass flowmeter, including:

Calibration solution device 1, which is used to provide a variety of calibration solutions with different densities; solution pump 3, which is used to provide power to flow the calibration solution in the calibration pipeline at a certain pressure; standard meter 4 and a plurality of mass flowmeters to be tested 5 is evenly installed on the calibration pipeline along the output end of the solution pump 3; the standard meter 4 is used to calibrate the density of the solution in the calibration pipeline; a computer 6 is connected to a plurality of mass flowmeters to be measured 5, Standard table 4 and switch 3; it is used to control the switch 3 to switch the calibration solution of different media to calibrate the density of the mass flowmeter 5, and write the calculated density calibration coefficient into the corresponding mass flowmeter 5 according to the density calibration mathematical model .

Wherein, the computer 6 can be replaced by an industrial computer or a terminal, and the calibration solution device 1 can be multiple, and each calibration solution device 1 is filled with a calibration solution with the same medium density; and the calibration solution device 1, the solution pump 3, the standard gauge 4. The mass flowmeters 5 are connected to each other using calibration pipes; and a switch 2 is set on the calibration pipe between the output end of each calibration solution device 1 and the solution pump 3, and the input end of each calibration solution device 1 A switch 2 is arranged on the connected calibration pipelines, and the switch 2 here ensures that only one medium calibration solution flows in the calibration pipeline in the density calibration system at a time.

A switch for controlling the flow of the calibration solution is arranged between the solution pump 3 and the standard meter 4, and a corresponding switch 2 is set here to ensure that the solution pump 3 flows the calibration solution to the standard meter 4 through its own power, and at the same time , when the switch is closed, the solution pump keeps running to displace the air bubbles in the calibration pipeline, wherein the switch 2 is a valve, a gate and a solenoid valve, preferably a solenoid valve, which can be directly controlled by the computer 6, through the computer 6 Remotely control and switch the calibration solutions in different media, and measure the density of the mass flowmeter 5 multiple times under each calibration solution, without human participation in the calibration process, and calculate the density of the mass flowmeter 5 to be tested through the density calibration mathematical model, Not only eliminates the calibration error of the traditional mass volume method, but also greatly improves the accuracy of the density calibration of the mass flow meter 5 .

If there is a requirement for the pressure and flow rate of the calibration solution in the density calibration system, a constant pressure and constant flow tank for steady flow and pressure can be provided between the solution pump 3 and the switch 2 close to the standard meter 4. By opening the constant pressure The exhaust switch on the constant flow tank device, until the calibration solution supplied by the solution pump 3 fills the constant pressure constant flow tank to the maximum, then close the exhaust switch, the purpose is to eliminate the air bubbles in the calibration solution and the non-constant pressure of the calibration solution In the state of constant current, if a constant pressure and constant current tank is to be installed here, it must be connected to a computer by the control bus to achieve the purpose of automatic control.

In the present application, the computer 6 communicates with the multiple mass flowmeters 5 to be tested, the standard meter 4 and the switch 2 through the control bus, and the computer sends instructions to control the opening and closing of the switch 2, and collects the standard meter 4 and the mass flowmeter. For the data of the flowmeter 5, the density value and accuracy of each mass flowmeter 5 to be tested are calculated according to the density calibration mathematical model. Among them, the number of mass flow meters 5 to be tested is at most ten, compared with the original method that can only calibrate at most three at the same time, which improves the efficiency of calibration.

In this application, the density calibration mathematical model is as follows:

In formula (1), ρ: the density of the mass flowmeter calibration measurement medium solution, unit kg/M ³ ; K _d : the density coefficient output by the calibration calculation, dimensionless; F _e (25): the mass flowmeter sensor at a constant temperature of 25 The resonant frequency of the measuring tube at ℃ temperature, unit Hz; F _kt : the correction coefficient related to the material, structure and temperature of the mass flowmeter sensor, usually the change of the resonant frequency of the sensor measuring tube for every increase or decrease of 1°C ; T: mass flowmeter sensor temperature; F _r : the actual output frequency of the mass flowmeter sensor when the measuring pipe is filled with the measurement medium solution, unit Hz; in the case of calculating K _d , calculate the mass flow rate according to the read F _r The density of the medium solution calibrated by the meter.

It also includes a fixed frame, which is arranged on both sides of the mass flowmeter 5 and the standard meter 4 to support its work. The fixed frame is preferably a cement support, which can not only eliminate the vibration of the pipeline, but also eliminate the mass flowmeter to be calibrated for density. The influence of the instrument can also eliminate the influence of the mass flowmeter 5 sensor itself on the density calibration due to the mechanical vibration. At the same time, the fixed frame is also used to isolate the mass flowmeters 5 of the whole machine to be calibrated online, and to prevent the mutual influence between the mass flowmeters 5 to be calibrated.

As shown in Figure 3, it is a structural diagram of an embodiment of a density calibration system for a mass flowmeter provided by the utility model; including:

In this embodiment, the number of mass flowmeters 5 to be calibrated is ten, and the standard meter 4 and ten mass flowmeters 5 are respectively installed in the calibration pipeline along the output direction of the solution pump 3 from left to right. Above, both sides of the mass flow meter 5 and the standard meter 4 are used to support the fixed frame for its work. The medium solution device 1 is divided into five calibration solutions filled with different media, wherein the first to fifth solenoid valves are respectively installed on the calibration pipelines at the output ends of the first to fifth medium solution devices 1, and the first to fifth solenoid valves are respectively installed. The sixth to tenth solenoid valves are respectively installed on the calibration pipelines at the input end of the medium solution device 1, and the calibration pipelines output by the tenth mass flowmeter 5 (that is, the rightmost mass flowmeter 5) are respectively connected to each medium solution The input end of the device 1, so that the calibration solution of each medium can return to the medium solution device 1 after circulating in the calibration pipeline, and the eleventh solenoid valve is installed on the calibration pipeline between the solution pump 3 and the standard gauge 4 .

The computer 6 is respectively connected to the standard meter 4, a plurality of mass flowmeters 5 and a plurality of electromagnetic valves through a control bus, and switches the calibration solution of each medium by controlling the electromagnetic valve switch. For example, when the eleventh electromagnetic valve is opened, The medium solution device 1 that needs to contain the calibration solution of a certain medium opens its solenoid valve and closes other solenoid valves so that the calibration solution of this medium flows to the entire density calibration system. When the calibration solution of this medium has no bubbles in the calibration pipeline And in a static state, read the output frequency of the mass flowmeter to be tested in sequence; calculate the density coefficient of each mass flowmeter to be tested through the density calibration mathematical model, and then repeat the above steps to obtain one or more In the case of the medium solution, the density of each mass flowmeter 5 to be tested is calculated according to the density of the mass flowmeter 5 to be tested, and the accuracy of the corresponding mass flowmeter is calculated.

In this embodiment, according to the above-mentioned density calibration method of the mass flow meter, including:

Step 1, initialize the density calibration system to ensure that the mass flowmeter to be tested tends to a stable state;

Specifically, during the initialization process of the density calibration system, the computer controls all switches to be closed, and the mass flowmeter to be tested is installed in the calibration pipeline to ensure that the mass flowmeter is in a sealed state, that is, there is no leakage; the standard meter and mass flow The meters are all powered on, and the computer is connected to the calibration meter, mass flowmeter and solenoid valve through the bus control; state.

Step 2, when the mass flowmeter is in an empty pipe state, sequentially read the output frequency value of the mass flowmeter to be tested;

Step 3, turn on the switch of a certain medium calibration solution device and the switch close to the standard meter, so that the calibration solution of this medium circulates in the calibration pipeline until the calibration solution flowing in the mass flowmeter to be tested has no bubbles;

Step 4, turn off the switch of the calibration solution device and the switch close to the standard meter until the calibration solution in the calibration pipeline is in a static state;

Step 5, read the current density value of the standard meter, and sequentially read the output frequency value of the mass flowmeter to be tested;

Step 6, under the calibration solution of different media, repeat steps 3 to 5 to obtain the density value of the standard meter and the frequency value output by the mass flowmeter to be tested;

Step 7, call the density calibration mathematical model to calculate the density coefficient of each mass flowmeter to be tested in turn, and write it into the corresponding mass flowmeter to be tested;

Step 8, under each medium calibration solution, repeat steps 3 to 4 multiple times to obtain the standard density value of multiple calibrations of the standard meter, and the density value output by the mass flowmeter to be tested multiple times;

In step 9, the accuracy of the mass flowmeter is calculated according to the corresponding standard density values in the calibration solutions of various media and the density values output by the mass flowmeter.

In this embodiment, the following process can be obtained by expanding the process of the above method, which is described in detail as follows:

1. Open the mass flowmeter density calibration system software in the industrial computer (computer), and close all the electromagnetic valves in the entire calibration system;

2. Install the mass flowmeter to be calibrated on the calibration pipeline in order from front to back (along the output direction of the solution pump, that is, the distance close to the solution pump is the front, and the distance away from the solution pump is the rear) to ensure no leakage state;

3. Power on and initialize the mass flow rate and standard table to be calibrated for density, and the communication bus is connected with the bus communication interface of the industrial computer;

4. Carry out communication detection of the mass flow rate and standard meter to be calibrated to ensure that each online mass flow rate and standard meter communicates normally with the mass flowmeter density calibration system software in the industrial computer;

5. Trigger the mass flowmeter density calibration system in the industrial computer to start the density calibration process of the online mass flowmeter;

6. Delay for about 3 minutes, so that the mass flow rate to be calibrated online is in or tends to a stable working state in the state of an empty pipe;

7. According to the numbering sequence from front to back, sequentially collect the mass flow rate data in the state of empty pipe for online density calibration;

8. Open the first solenoid valve, the sixth solenoid valve and the eleventh solenoid valve on the calibration pipeline through the control bus, and the other solenoid valves are closed;

9. Driven by the solution pump, the medium solution in the first medium solution device flows through the calibration pipeline, the standard meter, and the online mass flowmeter to be calibrated for density, and then flows back to the first medium solution device through the calibration pipeline after circulation. Work in this state for a few (five) minutes, until the entire calibration pipeline and the measuring tube of the mass flowmeter to be calibrated online are completely filled with the medium solution in the first medium solution device without air bubbles;

10. Close the first solenoid valve, the sixth solenoid valve and the eleventh solenoid valve on the calibration pipeline through the control bus until the density calibration medium solution in the entire calibration pipeline is in a calm and non-flowing state. For example, a delay of 1 minute can be used. Achieving a calm and no-flow state;

11. Read the standard density value currently output by the standard meter through the bus, and read the mass flow rate to be calibrated online in sequence according to the number sequence, and output the frequency value in this state;

12. Repeat steps 8)-11) to complete the density calibration process of the medium solution in the second to fifth medium solution devices; the only difference is that the controlled solenoid valves are different, as follows:

The density calibration of the second medium solution device needs to control the second solenoid valve, the seventh solenoid valve, and the eleventh solenoid valve;

The density calibration of the third medium solution device needs to control the third solenoid valve, the eighth solenoid valve, and the eleventh solenoid valve;

The density calibration of the fourth medium solution device needs to control the fourth solenoid valve, the ninth solenoid valve, and the eleventh solenoid valve;

The density calibration of the fifth medium solution device needs to control the fifth solenoid valve, the tenth solenoid valve, and the eleventh solenoid valve;

13. Calculate the density coefficient of each mass flowmeter in sequence according to the density calibration mathematical model of the internal package, and write the density coefficients into the online mass flowmeter converter in sequence;

14. Repeated detection and calculation of the density output accuracy of the online mass flowmeter;

15. Open the first solenoid valve, the sixth solenoid valve and the eleventh solenoid valve on the calibration pipeline through the control bus, and the other solenoid valves are closed;

16. Driven by the solution pump, the medium solution in the first medium solution device flows through the calibration pipeline, the standard meter, and the online mass flowmeter to be calibrated for density, and flows back to the first medium solution device through the calibration pipeline after circulation. Work in this state for a few (five) minutes, until the entire calibration pipeline and the measuring tube of the mass flowmeter to be calibrated online are completely filled with the medium solution in the first medium solution device without air bubbles;

17. Close the first solenoid valve, the sixth solenoid valve and the eleventh solenoid valve on the calibration pipeline through the control bus until the density calibration medium solution in the entire calibration pipeline is in a calm and non-flowing state. For example, a delay of 1 minute can be used. Achieving a calm and no-flow state;

18. Read the standard density value output by the standard meter at this time through the bus, read the density value output by the mass flow to be calibrated online in this state from front to back, and calculate the accuracy of the mass flow meter;

19. Repeat steps 15)-18), and detect the density of the medium solution in the first medium solution device for the second time;

20. The mass flowmeter density calibration system software repeats steps 15)-18), and detects the medium solution density in the first medium solution device for the third time, and calculates the repeatability of the online mass flowmeter density output in turn;

21. Repeat steps 15)-20) to complete the verification of the density output and repeatability of the medium solution in the second to fifth medium solution devices;

22. Report the density calibration and detection results (accuracy and repeatability) of online mass flowmeters for production users.

In summary, the utility model replaces the original manually operated density calibration system with a computer automatically controlled density calibration system. Compared with the original density calibration system, the number of each calibration is changed from three to ten, which improves the The efficiency of product calibration; use computer-controlled switches to switch calibration solutions in different media, and measure the density of the mass flowmeter multiple times under each calibration solution. There is no need for human participation in the calibration process, and the mass to be measured is calculated through the density calibration mathematical model. The density of the flowmeter not only eliminates the calibration error of the traditional mass volume method, but also greatly improves the accuracy of the density calibration of the mass flowmeter; at the same time, a constant pressure and constant flow tank is introduced in the density calibration system, eliminating the need for solution pumps The trickle of calibration solution and air bubbles produced during work essentially improve the calibration accuracy of the mass flowmeter. Therefore, the utility model effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present utility model, but are not intended to limit the present utility model. Anyone familiar with this technology can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the utility model should still be covered by the claims of the utility model.

Claims (8)

1. A density calibration system for a mass flowmeter, characterized in that it comprises: Calibration solution device, which is used to provide multiple calibration solutions with different densities; Solution pump, which is used to provide power to flow the calibration solution in the calibration pipeline at a certain pressure; A standard meter and a plurality of mass flowmeters to be tested are evenly installed on the calibration pipeline along the output end of the solution pump; The standard table is used to calibrate the density of the calibration solution in the pipeline; Computer, which is respectively connected to a plurality of mass flowmeters to be tested, standard meters and switches; it is used to control the switches to switch the calibration solutions of different media to calibrate the density of the mass flowmeters, and the calculated density will be calculated according to the density calibration mathematical model The calibration coefficient is written into the corresponding mass flow meter. 2. the density calibration system of mass flowmeter according to claim 1, is characterized in that, described calibration solution device is a plurality of, each calibration solution device all holds the calibration solution of same density, each calibration solution device A switch is provided on the calibration pipeline between the output terminal and the solution pump, and a switch is provided on the calibration pipeline connected to the input terminal of each calibration solution device. 3. The density calibration system of mass flowmeter according to claim 1, characterized in that a switch for controlling the flow of the calibration solution is arranged between the solution pump and the standard gauge. 4. The density calibration system of mass flowmeter according to claim 2 or 3, characterized in that the switch is a solenoid valve. 5. The density calibration system of mass flowmeter according to claim 1, characterized in that, a constant pressure and constant flow tank for steady flow and pressure is provided between the solution pump and the switch close to the standard meter. 6 . The density calibration system of mass flowmeter according to claim 1 , characterized in that, the computer communicates with the mass flowmeter to be tested, the standard meter and the switch through a control bus. 7 . 7 . The density calibration system for mass flowmeters according to claim 1 , further comprising a fixed frame, which is arranged on both sides of the mass flowmeter and the standard meter for supporting their work. 8 . 8. The density calibration system for mass flowmeters according to claim 1, characterized in that the number of the mass flowmeters to be tested is at most ten.