Basic Info.
Main Application
Water, Wastewater, Diesel Fuel, Fuel Oil, Nature Gas, Corrosive Liquid/Gas
Application
Industrial Production
Type
Volume Type Flow Meter
Measuring Principle
Electrical Principles
Measurement Object
Closed Pipeline
Certification
GB, CE, ISO, Sil
Origin
Tianchang City, Anhui Province, China
Product Description
Electromagnetic flow meters have a history of over 50 years of application and have been widely used in various industries such as water/wastewater, chemical, pharmaceutical, papermaking, and food. Large caliber instruments are commonly used in water supply and drainage engineering. Small and medium-sized caliber is commonly used in solid-liquid dual equality difficult to measure fluids or high demand areas. Small caliber and micro caliber are commonly used in places with hygiene requirements such as the pharmaceutical industry, food industry, and biotechnology.
With the acceleration of China's industrialization process, environmental pollution problems are becoming increasingly serious, and the call for sustainable development in society is also increasing. The concept of harmonious coexistence between humans and nature is accepted by people, and the governance of various types of pollution is becoming more urgent. Shaoxing Water Treatment Development Co., Ltd. is an urban comprehensive sewage treatment enterprise mainly engaged in printing and dyeing industrial wastewater. The first and second phases of the completed projects have reached a sewage treatment capacity of 700000 tons per day. Because in sewage treatment processes, it is necessary to measure and control the discharge of sewage, additives, sludge, etc., flow measurement is very important.
1 Measurement principle
The working principle of electromagnetic flowmeter is based on Faraday's law of electromagnetic induction. When a conductive metal rod moves at a certain speed perpendicular to the direction of the magnetic field line, an induced voltage is generated. If the magnetic field strength is B, the length of the metal rod is L, and the speed is v, then the induced voltage generated is: (see figure below)
Working principle diagram of electromagnetic flowmeter
In an electromagnetic flowmeter, the conductive medium inside the measuring tube is equivalent to a conductive metal rod in the Faraday test, and the two electromagnetic coils at the upper and lower ends generate a constant magnetic field. When a conductive medium flows through, an induced voltage is generated. The two electrodes inside the pipeline measure the induced voltage generated. The measurement pipeline achieves electromagnetic isolation from the fluid and measurement electrodes through non-conductive linings (such as rubber and Tflon).
Assuming that the magnetic field intensity (B) generated by the electromagnetic induction coil is constant, the induced voltage (Ue) generated is proportional to the fluid velocity (v), and the cross-sectional area of the pipeline (A) is known, the volumetric flow rate (Qv) can be calculated using the following formula:
The electromagnetic flowmeter consists of two main parts: a flow sensor and a transmitter. The sensor measurement tube is equipped with excitation coils above and below. After passing the excitation current, a magnetic field is generated and passes through the measurement tube. A pair of electrodes are installed on the inner wall of the measurement tube and come into contact with the liquid, leading out the induced electromotive force and sending it to the transmitter. The excitation current is provided by the transmitter. According to the assembly method of converters and sensors, there are two types: separated type and integrated type. In sewage treatment processes, large-diameter flow meters are mostly split type, with some installed underground and others above ground. Small caliber is mostly integrated.
There are also significant differences in the functions of electromagnetic flow meters in the market, with simple ones measuring unidirectional flow and only outputting analog signals to drive rear position instruments; Multi functional instruments include measuring bidirectional flow, range switching, upper and lower limit flow alarms, air traffic control and power supply cut-off alarms, small signal cut-off, flow display and total calculation, automatic verification and fault self diagnosis, communication with upper computer and motion configuration, etc. The serial digital communication function of some models of instruments can be equipped with multiple communication interfaces and chips (ASICs) to connect to the Hart protocol system, PROFIBUS, Modbus, FF fieldbus, etc.
The caliber range of electromagnetic flow meters is wider than other types of flow meters. E+H Company provides three types of sensors: W, P, and H, which are respectively applied in the water and sewage industries (W type), chemical and food industries (P type), and food and pharmaceutical industries (H type), with a caliber range of 2 millimeters to 2 meters. The transmitter can provide multiple choices of 10, 50, 23, and 53, with 10 being the economical type for water industry development, 50 being the ordinary type, 53 being the enhanced type, and 23 being the two wire system. There are two options for accuracy: 0.5% and 0.2%. It can measure both positive and negative flow rates, as well as pulsating flow rates.
The prerequisite for using an electromagnetic flowmeter is that the measured liquid must be conductive and cannot fall below the threshold (i.e. lower limit value). Conductivity below the threshold will result in measurement errors until it cannot be used, and even if it exceeds the threshold, it can be measured even if it changes. The indication error does not change much, and the threshold of a universal electromagnetic flowmeter is between 10-4 and (5) × Between 10-6) S/cm, it varies depending on the model. When in use, it also depends on the length of the flow signal line and its distributed capacitance between the sensor and converter. The manufacturer's user manual usually specifies the length of the signal line corresponding to the conductivity.
The conductivity of industrial water and its aqueous solution is greater than 10-4S/cm, and the conductivity of acid, alkali, and salt solutions is between 10-4-10S/cm. There is no problem with their use, and the conductivity of low alcohol distilled water is also 10-5S/cm. Electromagnetic flow meters cannot measure liquids with low conductivity, such as petroleum products and organic solvents. Cannot measure gases, vapors, and liquids containing large bubbles. It was found from the data that some pure or aqueous solutions have low conductivity and are considered unusable. However, in practical work, there may be instances where impurities are present and can be used, which are beneficial for increasing conductivity. For aqueous solutions, the conductivity in the data was measured in the laboratory using a pure water ratio. The actual aqueous solution used may use an industrial water ratio, and the conductivity will be higher than what was measured, which is also beneficial for flow measurement.
Characteristics of electromagnetic flow meters
Electromagnetic flow meters are not affected by external factors such as temperature, pressure, viscosity, etc. They measure the pressure loss caused by no contraction or protrusion inside the tube. In addition, the initial signal detected by the flow element is a voltage that varies linearly with the average flow rate of the fluid, independent of other properties of the fluid, and has great advantages. According to the characteristics of sewage such as large flow rate variation, impurity content, low corrosiveness, and certain conductivity, electromagnetic flowmeter is a good choice for measuring the flow rate of sewage. It has a compact structure and small volume. Easy to install, operate, and maintain, the measurement system adopts intelligent design, with enhanced overall sealing, and can work normally in harsh environments. However, due to technical reasons, it is difficult to enlarge the diameter of vortex flow meters, and the quality of pipeline ultrasonic flow meters lacks a competitive advantage in price compared to electromagnetic flow meters. So in the water and sewage industry, electromagnetic flow meters, especially large-diameter electromagnetic flow meters, have great advantages and have been widely used.
The E+H electromagnetic flowmeter has powerful functions and simple operation, with specific characteristics as follows:
1) Measure the flow components inside the pipeline without pressure loss, and the straight section requires bottom.
2) The measurement is not affected by changes in fluid density, viscosity, pressure, temperature, or conductivity.
3) There are various materials available for lining, such as hard rubber, polyurethane, PTFE, PFA, etc.
4) The DC/AC power supply, four wire/two wire system, explosion-proof/non explosion-proof, economy/standard types of the transmitter are subdivided to meet your different needs.
5) Photosensitive key, can avoid opening the lid operation; Chinese menu display, more convenient for domestic users to use.
6) Quick setting menu, guiding to complete parameter settings, convenient and fast.
7) High measurement reliability, good repeatability, and long-term maintenance free. Range ratio up to 1000:1
8) Provide various output methods such as current, frequency, pulse, Hart, Profibus PA, Profibus DP, FF, etc. for selection.
3 Installation requirements
The EMF series electromagnetic flowmeter provides a protection level of IP67 (dustproof and anti immersion level) or IP68 (dustproof and anti diving level). In sewage treatment plants, large diameter flow meter sensors are mostly installed underground, so it is recommended to choose IP68 (dustproof and submersible level). Usually, electromagnetic flow has the following requirements for the installation site:
1) When measuring mixed phase fluids, choose a location that will not cause phase separation; When measuring two-component liquids, avoid placing them downstream where the mixing is not yet uniform; When measuring chemical reaction pipelines, they should be installed downstream of the fully completed reaction section; Try to ensure that the front and rear straight pipe sections are not less than 5D and 2D respectively;
2) Try to avoid negative pressure inside the measuring tube as much as possible;
3) Choose a place with low vibration, especially for integrated instruments;
4) Avoid large motors, transformers, etc. nearby to avoid electromagnetic interference;
5) Places where it is easy to achieve separate grounding of sensors;
6) Try to avoid high concentrations of corrosive gases in the surrounding environment as much as possible;
7) Try to avoid direct sunlight as much as possible
4 Application situation and effect
The sewage treatment process mainly achieves the goal of sewage purification through processes such as biological oxidation, flocculation, and sedimentation, and requires a certain quantity meter for measurement at each stage. In the miscellaneous sewage industry, E+H mainly provides several products such as 10W, 50/53W, 23W, 50/53P, etc.
In the sewage treatment process, corresponding detection instruments need to be configured according to the process requirements to form a reliable control system. Shaoxing Sewage Treatment Plant is equipped with flow meters in the following process testing processes: (1) inlet pipe; (2) Detection of mud volume from initial sedimentation tank to sludge storage tank; (3) Residual sludge pump room and sludge flow detection; (4) Detection of return sludge flow rate in sludge pump room; (5) Detection of effluent flow rate of secondary sedimentation tank distribution well; (6) Detection of sludge inflow into the digestion tank; 7) Detection of sludge output from the digestion tank; (8) Detection of the dosage of coagulant in the flocculation tank, etc.
After being used in sewage treatment plants, the EMF series electromagnetic flowmeter runs well, and the operator reports that its measurement is accurate. The operation interface is user-friendly, and various parameters are clear at a glance. Moreover, the flowmeter installed on metal pipelines does not require a dedicated grounding ring. The EMF series electromagnetic flowmeter provides timely and accurate data for process detection and control, creating certain economic and social benefits.
Address:
20 Renhe South Road, Tianchang City, Chuzhou, Anhui, China
Business Type:
Manufacturer/Factory
Business Range:
Industrial Equipment & Components, Instruments & Meters
Management System Certification:
ISO 9001, ISO 14001
Company Introduction:
Anhui Tiankang (Group) Co., Ltd., founded in 1974, is located in Tianchang City on the bank of the Yangtze River, adjacent to the ancient city of Nanjing in the south and Yangzhou in the east. It is located in the vibrant "Yangtze River Delta" economic circle, with good investment and development prospects.
After more than 40 years of development, it has become a cross-industry and diversified group company with more than 30 subsidiaries and more than 6, 000 employees. Its products cover the fields of instrumentation, optical cables, medicine and medical care, protective supplies and new energy. With good quality and service, it is widely used in petroleum, electric power, chemical industry, communication, health, new energy and other industries. At the same time, the company has won a number of honorary titles such as China′s Top 500 private enterprise Manufacturing enterprises, China′s Top 100 electronic information enterprises, National high-tech enterprises, and National May Day Labor Award units.
The company has always adhered to the Tiankang spirit of "there is a leap to excellence", on the basis of creating a harmonious enterprise, constantly grasp the pulse of market development, actively seek economic strategic alliances, in the process of achieving high-quality development of enterprises, to revitalize the national industry and continue to work hard.