Abstract: This paper introduces the application of electromagnetic flowmeter in the production process of water supply enterprises and several matters that should be paid attention to. The experience summarized in the actual production process will be summarized for reference after rectification.
In recent years, the rapid and sustainable development of the social economy, the urban water supply situation is growing, the urban water supply area and scope are expanding year by year, and the total water supply is also increasing. With the requirements of automation and intelligence in the production process, the water supply side and the user side have higher and higher requirements on the accuracy and stability of the flow meter for water fee trade settlement. The sensor structure of the electromagnetic flowmeter is simple and unaffected. The temperature and viscosity of the measured medium, the measurement range is wide, there is no mechanical inertia, the reaction is sensitive, the instantaneous pulsating flow can be measured, and the flow in both the positive and negative directions can be measured. Therefore, electromagnetic flowmeters have been widely used in the case where the number of urban water supply enterprises is increasing year by year.
1.1 Basis for data indication in tap water production process
The installation of the electromagnetic flowmeter in the waterworks is required for the measurement of production. It can reflect the medicinal electrical changes and the matching of the pump required by the real-time data transmission to guide the production automation. By adjusting the drug consumption and power consumption, it can effectively Control production costs.
1.2 Management and monitoring of water supply areas
Due to the measurement accuracy, high stability of the electromagnetic flowmeter and the ability to measure the flow in both the forward and reverse directions, the water supply enterprise can analyze the flow rate of the local water supply area and provide water leakage and recovery of the water supply area. Digital basis. At the same time, through data reflection, the water supply requirements of the water supply area can be met through reasonable dispatch between the waterworks. With the pressure measuring system, the abnormal situation of the pipe network can be reflected in real time. When the pipe bursting condition is encountered, the leaking section can be locked early, the water stoppage caused by the bursting repair can be reduced, and the interests of the water supply enterprise can be guaranteed.
1.3 As the basis for trade settlement
Water meter is the main economic settlement tool for water supply enterprises. The general mechanical watch is prone to the phenomenon of staying in the table and stopping the watch. Some water meters are remote and scattered. It is a certain difficulty in meter reading and settlement, and the appearance of “estimate the table” and “human water” It has a negative impact on users and water companies. The use of the electromagnetic flowmeter solves the above problems, real-time data transmission and corresponding generation of record documents, and setting an abnormal flow alarm system to make the water supply safety and the accuracy of copying become scientific and reasonable.
During the installation and commissioning of a flowmeter located in the Jinben area of Sanshui District, Foshan City, the electromagnetic flowmeters at this location could not be measured normally due to power failure, module breakdown and signal interference caused by thunderstorms. It has a big impact on monitoring and settlement. Our company has made the following countermeasures for the above phenomena.
2.1 Power Supply Maintenance
Due to the need for real-time data transmission and recording, the electromagnetic flowmeter must be connected to the power supply network. However, any power outage will result in the loss of data, which will have a major impact on production management, pipe network monitoring and trade settlement. Therefore, under the premise of the situation, our company will supply the corresponding flow meter room or meter box to the electromagnetic flowmeter, and the built-in UPS uninterrupted battery to ensure the electricity demand of the electromagnetic flowmeter. The advantage of the UPS uninterruptible power supply is that its circuit design makes the whole machine more efficient, does not interfere with the power grid, achieves power loss reduction, and is reliable and durable. In the daily use and management process, our company pays attention to the regular discharge and maintenance of the UPS uninterruptible power supply, prolonging its service life, and at the same time solving the problem of power failure of the electromagnetic flowmeter.
2.2 Lightning protection measures
Due to the frequent thunderstorms in the south, electromagnetic flowmeters installed in open areas are susceptible to lightning strikes during thunderstorms, and even modules are subject to breakdown. Therefore, lightning protection grounding measures are particularly important for the protection of electromagnetic flowmeters.
In response to the lightning strike situation, our company carried out rectification of the lightning protection network on the flow meter room of the station. The specific scheme is shown in Figure 1.
Electromagnetic flowmeter lightning protection network rectification plan
Construction requirements for lightning protection nets: (1) along the direction of the medium round steel, excavation trenches, the round steel laying depth is not less than 80 cm; (2) 6 angle steels are connected by a diameter of 12 round steel, the welding position is full Welding, and applying anti-rust paint; (3) Ground net round steel is introduced into the room, the end welding nut is convenient for the equipment grounding wire connection; (4) After the ground net is welded, after the detection resistance is less than 2 Ω, it is backfilled.
2.3 Signal transmission
Since the components of the electromagnetic flowmeter include the transmitter and the converter, the transmitter will be interfered by different excitation modes in the environment. When the interference is severe, the flowmeter itself cannot be metered normally, which will seriously affect the water production and water supply. Schedule monitoring. Therefore, the signal to suppress and eliminate interference is also a key to the normal operation of the electromagnetic flowmeter.
For the signal interference situation, our company has carried out the rectification of the installation grounding of the electromagnetic flowmeter. The specific scheme is shown in Figure 2.
The electromagnetic flowmeter was rectified by the installation grounding
Flowmeter grounding construction requirements: (1) Excavate the trench next to the flowmeter well, the groove depth is not less than 80 cm; (2) hit the ground pole in the trench, the top of the ground is about 10 cm above the trench, The ground poles are welded with 12 mm diameter round steel and coated with anti-rust paint; (3) The ground net round steel is introduced into the flowmeter well, and the end welding nut facilitates the flange connection at both ends of the equipment. Connect with 25 m 2 copper wire; (4) After the ground wire connection is completed, the resistance needs to be checked. When the result is less than 2 Ω, it can be backfilled. In-phase interference can be reduced by connecting the flanges at both ends of the device. When connecting, be careful not to connect to the ground wire of the device. In order to improve the anti-interference ability, shielded wire transmission can be used between the transmitter and the conversion, and the signal wire and the power supply are respectively placed in different sleeves.
After rectification according to the above scheme, the UPS uninterruptible power supply is added and the electromagnetic flowmeter and other transmission equipment are grounded separately. During strong thunderstorms, the flowmeter equipment can operate normally without causing abnormality of the flowmeter caused by lightning strikes; signal interference The phenomenon still occurs, but the anti-interference ability is obviously enhanced, which improves the working efficiency of the flowmeter, and the overall effect is ideal.
3.1 Installation Management
The standard installation of electromagnetic flowmeter is an effective guarantee for the management of the water supply industry. According to the installation situation of our company, the following experiences are summarized:
(1) In order to ensure the measurement accuracy, the electromagnetic flowmeter safety pipeline requires a front straight pipe 10D and a rear straight pipe 5D to ensure the stable development of the flow state. In special cases, the installation of straight pipe 5D and rear straight pipe 3D can be used;
(2) There should be enough straight pipe sections in the flowmeter well to facilitate future measurement and testing;
(3) When installing, care should be taken to avoid interference from external magnetic fields and to avoid strong vibration of the flowmeter. If conditions permit, do a good job of heat insulation and waterproofing;
(4) Install backup power supply and make maintenance measures such as grounding lightning protection.
3.2 Daily management
In order to ensure the normal and safe operation of the flowmeter equipment, its performance is stable and accurate, and daily maintenance work is an important part. (1) The flowmeter manager must be familiar with the performance of the equipment and the handling of the fault. The management personnel will archive the original data and operating conditions of the flowmeter to facilitate timely processing of the data when the fault occurs. (2) Keep the flowmeter running the surrounding environment clean and daily inspection should pay attention to the power supply, indicator light and equipment display. (3) In order to ensure the accurate measurement of the flowmeter, the flowmeter is periodically verified and calibrated by the volumetric method or the standard gauge method, and can also be detected by the testing equipment provided by the manufacturer. In the absence of professional testing equipment, the multimeter can be used to measure the current and voltage through the flowmeter sensor for conversion detection. Analyze and record the actual operation of the flowmeter through inspection.
With the continuous development of modern technology, accurate and stable electromagnetic flowmeters have been promoted and applied in the water industry and other modern industrial fields. As the technical management personnel of the flowmeter in the water supply industry, it promotes the replacement of the flowmeter through standard management and experience, so that the highly intelligent measuring equipment guarantees safe water supply and accurate measurement.