CN114199351A

CN114199351A - Large-diameter sewage flow simulation and calibration device and method

Info

Publication number: CN114199351A
Application number: CN202111480581.XA
Authority: CN
Inventors: 方立德; 李志轩; 李红莲; 郭素娜; 赵宁; 王帆
Original assignee: Hebei University
Current assignee: Hebei University
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-03-18

Abstract

The invention provides a large-diameter sewage flow simulation and calibration device and method. The large-diameter sewage flow simulation and calibration device includes a water flow regulation system, a detection section and a return channel. The water flow control system is connected through the water supply pipe and the detection pipe in the detection section. A standard flow meter is installed on the water supply pipe, and a flowmeter to be tested is installed on the detection pipe. The detection pipe is set above the return channel, and the return channel is connected to the water flow control system. With the device in the present invention, the water flow can be adjusted by adjusting the frequency of the control gate valve or the lifting pump on the water supply pipe, and the state of the fluid in the detection pipeline under different flow rates can be simulated more comprehensively for measurement and calibration.

Description

Large-caliber sewage flow simulation and calibration device and method

Technical Field

The invention relates to the technical field of flow detection, in particular to a large-caliber sewage flow simulation and calibration device and method.

Background

With the attention of people and governments on environmental protection, sewage treatment projects are vigorously built all over the country, and as most of pipelines used for sewage treatment are pipelines with larger calibers, the verification of sewage pipeline flowmeters with larger calibers is an important part in verification work. However, as stated in "research on calibration method of large-caliber flow meter" by Miao nationality, the standardization of the large-caliber flow meter is still imperfect in China, and there is still an optimization space for the related technology and the calibration method. The patent application with the application number of 201711214191.1 discloses an on-line calibrating device for a large-caliber liquid flowmeter, which is mainly used for calibrating a calibrated liquid flowmeter installed on a liquid pipeline, uses an inserted flowmeter as a standard flowmeter, and solves the problem that the large-caliber flowmeter cannot be calibrated on site due to corrosion of the inner wall and the outer wall of the pipeline and narrow operation space of the pipeline. The patent application No. 201110396651.3 discloses a method for calibrating a large-caliber electromagnetic flowmeter on line, which comprises the steps of measuring geometric parameters of a pipeline, analyzing the flow form of liquid in the pipeline, analyzing the position of a sensitive point through mathematical modeling, then placing a temperature and pressure testing device for measurement, and finally obtaining the average flow velocity through data analysis. The calibration method for the large-caliber electromagnetic flowmeter is novel in concept and accurate in calibration on the premise of not changing a pipeline. The patent application No. 201621041635.7 discloses a flowmeter on-site verification and data processing system, which eliminates human errors caused by traditional manual visual inspection by improving the existing metal measuring device, changes the whole operation from the original manual operation into full-automatic data acquisition and calculation, reduces the system errors, and improves the detection precision and the measurement efficiency. In the research on the on-line calibration mode of the large-caliber electromagnetic flowmeter based on the standard meter fixed-point measurement transfer of Zhangfei, Gunn, Liuxiaoping and Shenqi, a method for improving the calibration precision by setting laboratory traceability data under the same conditions in a standard meter according to the caliber, the material and the flow rate of a pipeline of a flowmeter to be calibrated on site is provided.

More current research in calibrating large bore flow meters is an improvement over existing devices or methods. The various above certification devices and methods are directed to field calibration of large bore flow meters, and the design of calibration devices for large bore flow meters used in laboratories is relatively small.

Disclosure of Invention

The invention aims to provide a large-caliber sewage flow simulation and calibration device and method, which are convenient for calibrating and calibrating corresponding flowmeters in laboratories.

The invention is realized by the following steps: a large-caliber sewage flow simulation and calibration device comprises a water flow regulation and control system, a detection section and a backflow channel. The water flow regulation and control system is connected with a detection pipeline in the detection section through a water supply pipe, a standard flowmeter is installed on the water supply pipe, a flowmeter to be detected is installed on the detection pipeline, the detection pipeline is arranged above the backflow channel, and the backflow channel is connected into the water flow regulation and control system. By adopting the structure, the flow of water can be adjusted by adjusting the control gate valve on the water supply pipe, and the states of the fluid in the detection pipeline under different flow can be more comprehensively simulated for measurement and calibration.

Preferably, the water flow regulating and controlling system comprises a control system, a reservoir, a water supply pipe, a lift pump, a control gate valve and a standard flowmeter, wherein the water supply pipe is connected with the lift pump and the control gate valve in sequence and then is connected with the detection pipeline, the standard flowmeter is installed on the water supply pipe, and the control system is connected with the lift pump, the control gate valve and the standard flowmeter. By adopting the structure, after the flow required by detection is set, the control system can automatically adjust by reading the reading of the standard flowmeter, so that the flow meets the set value.

Preferably, the control system regulates the flow in the supply line in two ways: the frequency of the frequency converter is adjusted or the opening degree of the control gate valve is adjusted, and the mode of adjusting the frequency converter is more energy-saving and accurate, so that the mode of adjusting the frequency converter is used by default when in use, and the mode of adjusting the opening degree of the control gate valve can be changed into the mode of adjusting the opening degree of the control gate valve when special needs exist.

Preferably, the water outlet of the water supply pipe is in a flat fan-shaped structure, and the water outlet of the water supply pipe extends into the detection pipeline and seals the interface of the water outlet and the detection pipeline. By adopting the structure, the water outlet flow of the water supply pipe is more uniform, and the uncertainty of overlarge water flow is reduced.

Preferably, in the detection pipeline, three layers of baffles are sequentially arranged between the water outlet of the water supply pipe and a detection point of the flowmeter to be detected, and the heights of the three layers of baffles are sequentially reduced along the water flow direction. With the structure, when the three layers of the baffles are filled, and fluid enters the detection pipeline from the water supply pipe, an equal amount of fluid overflows from the baffles and flows through the measurement point of the flowmeter to be detected. Therefore, after the three layers of baffles are full, the flow rate flowing through the flowmeter to be detected in unit time is equal to the flow rate entering the detection pipeline from the water supply pipe, namely equal to the flow rate flowing through the standard flowmeter. The water flow in the detection pipeline can be enabled to accord with the characteristic of gravity flow, the buffering and rectifying effects on the incoming flow are achieved, the flow velocity is more uniform, and the detection accuracy is improved.

Preferably, a temperature sensor and a flow velocity sensor are arranged in the detection pipeline, so that the water flow condition is monitored in real time, and the data can be used for analyzing the influence of the water temperature and the flow velocity on the measurement result.

Preferably, the backflow channel is a rectangular groove, one end of the rectangular groove, which is located below the detection pipeline, is closed, and one end of the rectangular groove, which is connected to the reservoir, is opened. By adopting the structure, the water can quickly flow back to the reservoir of the water flow regulating and controlling system after the water outlet of the detection pipeline is received.

The device provided by the invention can be used for carrying out large-caliber sewage flow simulation and calibration work in a laboratory, can be used for calibrating and calibrating the flowmeter to be tested in different flow states, is simple to operate and convenient to test, and has relatively accurate calibration and calibration results due to relatively small errors.

Drawings

FIG. 1 is a schematic view of the structure of the apparatus of the present invention.

FIG. 2 is a functional block diagram of a water flow regulation system of the present invention.

FIG. 3 is a flow chart of a method of the present invention.

In the figure: 1. a reservoir; 2. a water supply pipe; 3. a lift pump; 4. controlling a gate valve; 5. detecting a pipeline; 6. a baffle plate; 7. a temperature sensor; 8. a return channel; 9. a first support bar; 10. a second support bar; 11. a standard flow meter; 12. a flowmeter to be detected; 13. a flow rate sensor.

Detailed Description

As shown in fig. 1, the large-caliber sewage flow simulation and calibration device provided by the invention is a flow circulation system, and mainly comprises a water flow regulation and control system, a detection section and a return canal.

Water flow regulating and controlling system

The water flow regulating system is the main control part of the device of the invention and comprises a water reservoir 1, a lift pump 3, a control gate valve 4, a standard flow meter 11, a water supply pipe 2 and a control system (not shown in figure 1).

The water storage tank 1 is filled with sewage, the lift pump 3 is arranged in the water storage tank 1, and the lift pump 3 is used for pumping the water in the water storage tank 1 out to the water supply pipe 2. One end of the water supply pipe 2 is extended into the water reservoir 1, and the end of the water supply pipe 2 is connected to the lift pump 3. One end of the water supply pipe 2 extending into the reservoir 1 is a water inlet, and the other end is a water outlet, and the height of the water outlet is far higher than that of the water inlet. The water supply pipe 2 is further provided with a control gate valve 4, and the amount of water flow flowing into the water supply pipe 2 can be controlled by controlling the opening degree of the valve of the control gate valve 4. The control gate valve 4 is provided above the lift pump 3. The water supply pipe 2 is further provided with a reference flowmeter 11, the reference flowmeter 11 is positioned above the control gate valve 4, and the flow rate of water flowing through the water supply pipe 2 can be detected by the reference flowmeter 11.

The lift pump 3, the control gate valve 4 and the standard flowmeter 11 are all connected with a control system, and with reference to fig. 2, the control system of the invention adopts a Mitsubishi FX3U series PLC control system, the control system is externally connected with a touch screen for display and operation, the control system outputs data to a computer, the computer stores and calculates experimental data, and the computer can also be externally connected with a printer for printing verification reports. The control system can control the start and stop of the lifting pump 3 and the opening degree of a valve on the control gate valve 4, and the flow reading measured by the standard flowmeter 11 can be read by the control system. Before specific calibration, the flow required by measurement is preset in a control system, a lift pump 3 is started, a control gate valve 4 is opened, water flows through a detection point of a standard flow meter 11, the control system reads the reading of the standard flow meter 11 to control the opening of the control gate valve 4 and the frequency of the lift pump 3 (the frequency of the lift pump is controlled by a frequency converter), and the flow in a water supply pipe 2 is regulated and controlled to meet the requirement.

Detection section-

The structure of the detection section mainly comprises a detection pipeline 5, a support rod, a baffle 6, a temperature sensor 7, a flow velocity sensor 13 and a flowmeter 12 to be detected. The detection pipeline 5 is transversely arranged, the height of the detection pipeline 5 is higher than that of the water storage tank 1, and the lift pump 3 outputs water in the water storage tank 1 to the detection pipeline 5 through the water supply pipe 2. Therefore, the other higher port (i.e. the water outlet) of the water supply pipe 2 extends into the detection pipeline 5 from one end (the water inlet end) of the detection pipeline 5, moreover, the water outlet of the water supply pipe 2 is designed into a flat fan-shaped structure, and the place where the water supply pipe 2 is connected with the detection pipeline 5 is sealed by sealant.

The detection duct 5 is supported by a support rod. The bracing piece sets up in the below that detects pipeline 5, specifically, the bracing piece is including setting up two first bracing pieces 9 and two second bracing pieces 10 that set up in the left below of detection pipeline 5 in the below on detection pipeline 5 below right side, and the position that four spinal branch vaulting poles and detection pipeline 5 bottom contacted is connected with the bearing so that rotate. In the embodiment of the present invention, the two second support rods 10 on the left side are close to the water inlet end of the detection pipeline 5, and the two first support rods 9 on the right side are close to the water outlet end of the detection pipeline 5. The two second support bars 10 on the left side are designed as fixed support bars, and the two second support bars 10 have the same height. Two first bracing pieces 9 on the right side are telescopic bracing pieces, namely the height of the right end of the detection pipeline 5 can be adjusted by adjusting the first bracing pieces 9, or the inclination or slope of the detection pipeline 5 can be adjusted. However, the height of the first support bar 9 is adjusted to be not more than the height of the left second support bar 10 at the highest to prevent the fluid from flowing back in the sensing tube 5. The heights of the two first supporting rods 9 are equal.

Be provided with baffle 6 near its water inlet end department in detecting pipeline 5, baffle 6 sets up the right side at delivery pipe 2 delivery port promptly, by delivery pipe 2 delivery port outflow water get into in detecting pipeline 5 in the back, at first blockked by baffle 6, consequently baffle 6 plays and is used for buffering rivers. In the specific implementation of the invention, the baffle 6 is designed into a three-layer structure, which specifically comprises the following steps: from left to right (or along rivers direction) be provided with first layer baffle, second floor baffle and third layer baffle according to the preface, these equidistant setting of three-layer baffle, moreover, the height of these three-layer baffle reduces according to the preface along rivers direction, is the echelonment and distributes. The water flowing out of the water outlet of the water supply pipe 2 is firstly accumulated at the first layer of baffle plate, and when the liquid level is higher than that of the first layer of baffle plate, the water flows to the second layer of baffle plate; when the liquid level is higher than the second layer of baffle plates, the water flow overflows to the third layer of baffle plates; when the liquid level is higher than the third layer of baffle, the water flow overflows from the third layer of baffle, and then the water flow starts to flow freely in the detection pipeline 5. The structure of the baffle 6 should be adapted to the inner wall of the detection pipeline 5, namely: the baffle 6 is a plate-shaped structure with an arc-shaped lower part and a straight line upper part.

A temperature sensor 7 and a flow rate sensor 13 are arranged on the right side of the three-layer baffle plate, and the temperature and the flow rate of the water flow in the detection pipeline 5 are detected through the temperature sensor 7 and the flow rate sensor 13. A flowmeter 12 to be detected is arranged on the right side of the two sensors on the detection pipeline 5, and the flowmeter 12 to be detected is used for monitoring the water flow condition in real time. After passing through the flowmeter 12 to be detected, the water finally flows out from the water outlet at the right end of the detection pipeline 5. The water outlet at the right end of the detection pipeline 5 is arranged at the bottom position of the detection pipeline 5 close to the right end.

The temperature sensor 7, the flow velocity sensor 13 and the flowmeter 12 to be detected are all connected with a control system in the water flow regulating and controlling system, and data detected by the temperature sensor 7, the flow velocity sensor 13 and the flowmeter 12 to be detected can be read in real time through the control system.

③ return channel

The return channel 8 is a rectangular groove structure which is obliquely arranged, and the opening of the rectangular groove faces upwards. The water flowing out of the water outlet at the right end of the detection pipeline 5 flows into the return channel 8 and can flow into the reservoir 1 along the return channel 8. The upper end of the return channel 8 is therefore located to the right below the test tube 5 and is closed so that water from the outlet at the right end of the test tube 5 can fall directly into the return channel 8. The lower end of the return channel 8 projects into the reservoir 1 and is open. The water flowing out of the detection pipeline 5 enters the backflow channel 8, and under the action of gravity, the water automatically flows into the reservoir 1 along the backflow channel 8, so that the circulation of water flow is realized.

As shown in fig. 3, the specific process of simulation and calibration using the apparatus of the present invention is as follows: firstly, a switch is opened, the lift pump 3 starts to work, the control gate valve 4 is opened, and a calibration scheme is set in the control system, wherein the calibration scheme comprises the required measurement times, the number of groups for reading experimental data in each measurement, the flow in the pipeline required by each measurement and the flow regulation and control mode (adjusted by a frequency converter or the control gate valve). The control system automatically detects the reading of the standard flow meter and changes the frequency of the lift pump or the opening of the control gate valve until the flow in the conduit meets the set point (it can be assumed that the set point is met when the error between the two is less than a certain value, e.g. the set point is met when the error between the two is less than 5%). If the flow in the pipeline does not meet the set value (if the error between the flow and the set value is more than or equal to 5 percent), the PID algorithm is needed to calculate the control quantity, then the frequency of the lift pump or the opening of the control gate valve is changed, and after about 2 seconds of delay, the control system detects the reading of the standard flowmeter until the requirement is met. When the flow in the pipeline meets the set value, the control system can simultaneously read the readings of the set group number standard flowmeter, the flowmeter to be detected and the temperature sensor and the flow velocity sensor in the detection pipeline, and process and display the experimental data. The calibration of the flowmeter to be detected under the condition of different flow rates in the pipeline can be realized by setting different calibration schemes.

The device of the invention uses the control system to read simultaneously, so human errors do not exist, and under the condition of good overall tightness of the device, the errors of the device mainly come from the frequency of the lift pump, the instability of water flow, the change of temperature and flow rate and the standard flowmeter. The baffle plate with the rectifying function is arranged in the detection pipeline, so that water flow entering the detection pipeline is buffered, the stability of the water flow is greatly increased, and errors caused by instability of the water flow can be ignored. The uncertainty of the error in other respects is analyzed below.

(1) Control system controls the uncertainty introduced by the flow size in the water supply pipe

The vector control type frequency converter is adopted to carry out closed-loop control on the output frequency, so that the stability of the flow rate of the lift pump is improved, the error of the output frequency of the frequency converter is about 2.5%, and the error can be further reduced by additionally arranging the isolator. However, the PLC program regulates and controls the frequency converter by detecting the flow in the water supply pipe, so the output frequency error of the frequency converter does not influence the actual flow in the regulated and controlled water supply pipe. As described above and shown in fig. 3, the provisional allowable flow error is 5%, and in a uniform distribution,

then its class B relative standard uncertainty is:

(2) temperature sensor error induced uncertainty

The uncertainty of the platinum thermistor temperature measurement was found to be 0.5 deg.C. The water temperature is set to be about 15 ℃ during verification, and the water is uniformly distributed,

then its class B relative standard uncertainty is:

(3) flow rate sensor error induced uncertainty

Through investigation, the precision of the current flow meter on the market is about 1 percent, and the flow meters are uniformly distributed,

then its class B relative standard uncertainty is:

(4) standard flow meter error induced uncertainty

The standard flow meter error is the error of the flow meter itself, which acts as a standard flow meter. According to investigation, the highest precision of the electromagnetic flowmeter on the market at present can reach 0.3%, and if the electromagnetic flowmeter is adopted, the standard flowmeter error is 0.3%. According to the uniform distribution of the components,

then its class B relative standard uncertainty is:

。

Claims

1. a large-diameter sewage flow simulation and calibration device, is characterized in that, comprises three parts of water flow control system, detection section, return channel;

The water flow regulation system includes a water reservoir, a lift pump, a control gate valve, a standard flow meter, a water supply pipe and a control system; fluid water is contained in the water reservoir; the water inlet of the water supply pipe extends into the water reservoir , the lift pump is located in the reservoir and is arranged at the end of the water supply pipe, the lift pump is used to pump out the water in the reservoir and flow into the detection section through the water supply pipe; the control gate valve is arranged at the end of the water supply pipe. on the water supply pipe and above the lift pump, the standard flow meter is arranged on the water supply pipe and above the control gate valve;

The detection section includes a horizontal detection pipeline and a flowmeter to be detected arranged on the detection pipeline; the water outlet of the water supply pipe extends into the detection pipeline from the water inlet end of the detection pipeline;

The return channel is arranged obliquely, and its higher end is located below the detection pipeline, and its lower end is connected to the reservoir; the water flowing out from the water outlet end of the detection pipeline can freely fall into the return channel and flow into the return channel along the return channel. in a cistern;

The lift pump, the control gate valve, the standard flow meter and the flow meter to be tested are all connected to the control system, and the control system can control the frequency of the lift pump and/or control the opening of the gate valve, thereby controlling the water Flow size; the control system can also read the data detected by the standard flowmeter and the flowmeter to be checked.

2 . The large-diameter sewage flow simulation and calibration device according to claim 1 , wherein a buffer for water flow is provided between the water outlet of the water supply pipe and the flowmeter to be tested in the detection pipeline. 3 . Rectifying baffle.

3. The large-diameter sewage flow simulation and calibration device according to claim 2, wherein the baffle comprises a three-layer structure, the three-layer baffles are arranged at equal intervals, and the heights of the three-layer baffles are along the water flow direction decreasing in turn.

4 . The large-diameter sewage flow simulation and calibration device according to claim 2 , wherein a temperature sensor and a flow rate sensor are arranged in the detection pipeline between the baffle and the flowmeter to be detected. 5 .

5. The large-diameter sewage flow simulation and calibration device according to claim 1, wherein the return channel is a rectangular groove structure with an upper opening; the higher end of the return channel is closed, and the lower end is open .

6. The large-diameter sewage flow simulation and calibration device according to claim 1, wherein the detection pipeline is supported by a total of four support rods in two groups on the left and right; wherein, the two support rods on the left are fixed support rods, and The two left support rods are close to the water inlet end of the detection pipe; the right two support rods are telescopic support rods, and the right two support rods are close to the water outlet end of the detection pipe; the height of the telescopic support rods is not higher than The height of the fixed support rod.

7. The large-diameter sewage flow simulation and calibration device according to claim 1, wherein the water outlet of the water supply pipe has a flat fan-shaped structure, and the water outlet of the water supply pipe extends into the detection pipe, and is in two The joints are sealed with sealant.

8. The large-diameter sewage flow simulation and calibration device according to claim 1, wherein the control system is a Mitsubishi FX3U series PLC control system.

9. A method for simulating and calibrating large-diameter sewage flow, comprising the steps of:

a. Set up the large-diameter sewage flow simulation and calibration device as claimed in claim 1;

b. Set the calibration plan in the control system, the calibration plan includes the number of measurements required, the number of groups of experimental data read for each measurement, the flow in the pipeline required for each measurement, and the method of regulating the flow; the method of regulating the flow To change the frequency of the lift pump or control the opening of the gate valve;

c. Open the control gate valve and open the switch of the lift pump, so that the water in the reservoir flows into the detection pipeline through the water supply pipe under the action of the lift pump;

d. The reading of the standard flowmeter is automatically detected by the control system, and the flow in the water supply pipe meets the requirements by changing the frequency of the lift pump or controlling the opening of the gate valve;

e. The control system simultaneously reads the readings of the set number of standard flowmeters and the flowmeters to be inspected, and processes and displays these data.

10. The method for simulating and calibrating large-diameter sewage flow according to claim 9, wherein a temperature sensor and a flow rate sensor are also provided in the detection pipeline, and the temperature sensor and the flow rate sensor are both connected to the control system , When the control system reads the readings of the standard flowmeter and the flowmeter to be checked, it also reads the readings of the temperature sensor and the flow rate sensor.