Abstract: Electromagnetic flowmeters are widely used because they have smooth and straight sections and a high resistance to corrosion. The measured volume flow is virtually unaffected by fluid density, viscosity, temperature, pressure, and electrical conductivity. Various industrial production. In this project, the electromagnetic flowmeter was changed locally to make it more effective in the production control process, and at the same time, the reliability of the equipment operation was improved.
Keywords: electromagnetic flowmeter lining material solid content ore slurry 1 Overview With the rapid development of industrial automation, various smart instruments are playing an increasingly important role in industrial design. In modern industrial production, the application of intelligent systems is becoming more and more extensive, which also reduces the possibility of man-made problems in production. However, the accuracy and operability of various instruments have also increased. The following is a discussion of the application, problems and solutions of the electromagnetic flowmeter with high solid content in the extraction of vanadium pentoxide from a certain stone coal.
2 Introduction to process flow This project is a comprehensive utilization of stone coal. The existing vanadium extraction process produces a large amount of waste residue. Its main component is silica, but it contains a lot of vanadium resources, and the utilization of vanadium resources is low. At the same time, the content of alkali in the waste slag is high. If the waste slag is randomly stacked, it will cause environmental pollution. The main feature of this project is to use the vanadium secondary slag in the existing vanadium extraction process as the main raw material for the preparation of precipitated silica, and to fully utilize the silicon resources in the waste residue. The company has created new economic growth points for the company and at the same time solved the problems of vanadium resource waste and environmental pollution caused by the existing vanadium production. In addition, the project uses the waste heat generated in the decarbonization process of the existing vanadium production line as a heating source. It replaces the traditional method of using bituminous coal as the main fuel, that is, the waste heat generated in the production has been effectively and reasonably used, which further reduces the fuel cost, achieves the purpose of energy conservation and emission reduction, and comprehensive utilization of resources, and the process flow The block diagram is as follows.
During the preparation of the slurry, a certain amount of sodium hydroxide is added to make the vanadium in the ore dissolve as much as possible in the alkaline solution. The solid content in the slurry produced is relatively high, about 50%, in order to ensure the next process. For stable operation and product quality, accurate metering of the amount of slurry added to the dissolving tank is required. And through the DCS control system to control the opening of the valve. To ensure the stability of the flow. This puts high demands on the anti-corrosion, corrosion resistance and accuracy of the flowmeter. This article mainly elaborates on the correct selection of flowmeters in the project and the use of electromagnetic flowmeters in high solid content slurries.
3 Flowmeter selection method In industrial production, the measurement of the four thermal parameters of temperature, pressure, flow, and liquid level is generally considered to be the most difficult to achieve the expected accuracy and reliability of flow measurement. This relates to issues such as the supply of the process database, the selection of the instrument, the correct installation and use, and of course the quality of the instrument itself.
When selecting the flow measurement instrument, the main consideration is the suitability of the process media and application conditions, as well as the scale, function, accuracy, and economics of the instrument.
The electromagnetic flowmeter is a meter for measuring the conductivity of a liquid in accordance with Faraday's electromagnetic induction law. From its working principle, it is in accordance with the condition of the alkaline solution with high solid content proposed by the project for the flow meter.
4 In this project, the electromagnetic flowmeter selection problems and solutions to discuss 4.1 Electromagnetic flowmeter working principle Electromagnetic flowmeter is based on Faraday's electromagnetic induction law made of a measuring liquid leakage instrument. That is, when a conductor cuts magnetic field lines in a magnetic field, an induced potential is generated in the conductor. The magnitude of the induced potential is proportional to the magnetic induction intensity and the strength of the magnetic force of the cutting fluid.
4.2 Advantages and Disadvantages of Electromagnetic Flowmeters 4.2.1 Advantages of Electromagnetic Flowmeters (1) The measurement channel is a straight, straight section of tubing that will not block and is suitable for the measurement of liquid-solid two-phase fluids containing solid particles, such as pulp, sludge, sewage, etc. .
(2) No pressure loss caused by flow detection.
(3) The measured volumetric flow is virtually unaffected by the fluid density, viscosity, temperature, pressure, and conductivity.
(4) Within the flow range, wide range of caliber.
(5) Corrosive fluids may be applied.
4.2.2 Disadvantages of Electromagnetic Flowmeters (1) Fluids with very low conductivity cannot be measured.
(2) Gas, steam, and liquids containing large bubbles cannot be measured.
(3) Cannot be used for higher temperature fluids.
4.3 Liner discussion of electromagnetic flowmeters The following lining materials are analyzed, discussed and selected based on the characteristics of the medium.
4.3.1 Neoprene (1) Main performance: 1 oil, solvent, oxidation resistance, resistance to general acid, alkali, salt and other media corrosion; 2 has excellent elasticity, wear resistance, but poor cold resistance.
(2) Scope of application: Non-acidic, strong alkali, strong oxidizing medium at 10°C~80°C; 2 Measurable sewage and mud.
4.3.2 Natural rubber (1) Main properties: 1 Better wear resistance, corrosion resistance, insulation and low temperature resistance. 2 poor oil resistance, poor aging resistance and oxidation resistance.
(2) Applicable range: -10°C～70°C Non-strong acid, strong alkali, strong oxidizing medium, suitable for drinking water.
4.3.3 Polyurethane rubber (1) Main properties: 1 It has excellent abrasion resistance and elasticity; 2 It has poor acid and alkali resistance.
(2) Scope of application: 1-25°C～60°C; 2 Neutral strong wear of pulp, coal slurry and mud.
4.3.4 Teflon (1) The main performance: 1 hydrophobic and non-sticky, strong high temperature resistance; 2 has excellent corrosion resistance, strong acid resistance, strong alkali, organic solvents and various salt solutions; 3 Good anti-vacuum capacity, high anti-negative pressure can add metal mesh, improve negative pressure resistance; 4 poor wear resistance.
(2) Scope of application: 1-25 °C ~ 140 °C non-strong wear medium; 2 sanitary media.
4.3.5 Polytetrafluoroethylene (1) Main properties: 1 is a kind of material with the most stable chemical properties in plastics. It is resistant to boiling hydrochloric acid, sulfuric acid, nitric acid, and aqua regia. It is also resistant to concentrated alkali and various organic solvents. Chlorine trifluoride, high temperature oxygen trifluoride, high flow rate of liquid chlorine, liquid chlorine, ozone corrosion; 2 poor wear resistance; 3 poor resistance to negative pressure.
(2) Scope of application: 1-25°C～140°C; 2 strong corrosive medium such as concentrated acid and alkali; 3 Hygienic medium.
4.3.6 Fluorinated Ethylene Propylene (3) Main properties: 1 Hydrophobicity and non-adhesion; 2 Corrosion resistance second only to Teflon; 3 Metal nets can be added to improve the negative pressure resistance when the negative pressure resistance is high. ; 4 poor wear resistance.
(4) Scope of application: 1-25°C～100°C non-strong wear medium; 2 Hygienic medium.
4.4 Problems encountered during application and methods for solving them Through the discussion of several types of lining materials mentioned above, it is not difficult to find that chloroprene rubber and natural rubber have a good wear resistance but poor corrosion resistance. Although Teflon, PTFE, and fluorinated ethylene propylene can meet alkali corrosion resistance, wear resistance is not very good. After repeated comparisons, the PTFE with the best stability was selected for trial operation to test the performance of the electromagnetic flowmeter.
The flowmeter was used for 2 to 3 months before it could not be used normally; to clarify the reason. After removing the electromagnetic flowmeter, it was found that there was no problem with the lining at the outlet of the electromagnetic flowmeter, but there was a detachment phenomenon from the measurement tube at the flanging of the flange outer lining material at the entrance. A gap appeared between the lining and the metal measuring tube, which caused the liquid to enter the gap, resulting in the meter not being used normally.
After clarifying the reasons for this problem, they communicated with the manufacturers and discussed with engineers and technicians. Decided to take two measures to solve this problem: 1 further optimize the control in the refining process, so that the solid particle diameter in the slurry to reduce the erosion of the electromagnetic flow meter at the entrance; 2 reduce the flow rate of slurry delivery; 3 A 2~3mm thick stainless steel gasket is added to the inlet of the electromagnetic flowmeter and the flange of the pipeline to reduce the erosion of the flanged lining material at the entrance flange of the electromagnetic flowmeter. Stainless steel gaskets can be changed regularly. After the above measures were taken, obvious results were achieved. After nearly two years of operation assessment, the electromagnetic flowmeter was stable in operation, accurate in measurement, and free from failure. Therefore, in this project, it is feasible to use electromagnetic flowmeters made of Teflon-lined materials for solids with higher solids content.
5 Concluding remarks As an instrument electrical professional engineer, how to better understand the situation of the process media, understand the characteristics and advantages and disadvantages of each type of flowmeter itself, and discover the problems that may arise in some projects, and the ability to solve problems is our Constant work should be improved. The improvement of the conditions for the use of electromagnetic flowmeters is a useful attempt, and it also increases our awareness of innovation.
Keywords: electromagnetic flowmeter lining material solid content ore slurry 1 Overview With the rapid development of industrial automation, various smart instruments are playing an increasingly important role in industrial design. In modern industrial production, the application of intelligent systems is becoming more and more extensive, which also reduces the possibility of man-made problems in production. However, the accuracy and operability of various instruments have also increased. The following is a discussion of the application, problems and solutions of the electromagnetic flowmeter with high solid content in the extraction of vanadium pentoxide from a certain stone coal.
2 Introduction to process flow This project is a comprehensive utilization of stone coal. The existing vanadium extraction process produces a large amount of waste residue. Its main component is silica, but it contains a lot of vanadium resources, and the utilization of vanadium resources is low. At the same time, the content of alkali in the waste slag is high. If the waste slag is randomly stacked, it will cause environmental pollution. The main feature of this project is to use the vanadium secondary slag in the existing vanadium extraction process as the main raw material for the preparation of precipitated silica, and to fully utilize the silicon resources in the waste residue. The company has created new economic growth points for the company and at the same time solved the problems of vanadium resource waste and environmental pollution caused by the existing vanadium production. In addition, the project uses the waste heat generated in the decarbonization process of the existing vanadium production line as a heating source. It replaces the traditional method of using bituminous coal as the main fuel, that is, the waste heat generated in the production has been effectively and reasonably used, which further reduces the fuel cost, achieves the purpose of energy conservation and emission reduction, and comprehensive utilization of resources, and the process flow The block diagram is as follows.
During the preparation of the slurry, a certain amount of sodium hydroxide is added to make the vanadium in the ore dissolve as much as possible in the alkaline solution. The solid content in the slurry produced is relatively high, about 50%, in order to ensure the next process. For stable operation and product quality, accurate metering of the amount of slurry added to the dissolving tank is required. And through the DCS control system to control the opening of the valve. To ensure the stability of the flow. This puts high demands on the anti-corrosion, corrosion resistance and accuracy of the flowmeter. This article mainly elaborates on the correct selection of flowmeters in the project and the use of electromagnetic flowmeters in high solid content slurries.
(Map Stone Coal Comprehensive Utilization Process Flow Diagram)
3 Flowmeter selection method In industrial production, the measurement of the four thermal parameters of temperature, pressure, flow, and liquid level is generally considered to be the most difficult to achieve the expected accuracy and reliability of flow measurement. This relates to issues such as the supply of the process database, the selection of the instrument, the correct installation and use, and of course the quality of the instrument itself.
When selecting the flow measurement instrument, the main consideration is the suitability of the process media and application conditions, as well as the scale, function, accuracy, and economics of the instrument.
The electromagnetic flowmeter is a meter for measuring the conductivity of a liquid in accordance with Faraday's electromagnetic induction law. From its working principle, it is in accordance with the condition of the alkaline solution with high solid content proposed by the project for the flow meter.
4 In this project, the electromagnetic flowmeter selection problems and solutions to discuss 4.1 Electromagnetic flowmeter working principle Electromagnetic flowmeter is based on Faraday's electromagnetic induction law made of a measuring liquid leakage instrument. That is, when a conductor cuts magnetic field lines in a magnetic field, an induced potential is generated in the conductor. The magnitude of the induced potential is proportional to the magnetic induction intensity and the strength of the magnetic force of the cutting fluid.
4.2 Advantages and Disadvantages of Electromagnetic Flowmeters 4.2.1 Advantages of Electromagnetic Flowmeters (1) The measurement channel is a straight, straight section of tubing that will not block and is suitable for the measurement of liquid-solid two-phase fluids containing solid particles, such as pulp, sludge, sewage, etc. .
(2) No pressure loss caused by flow detection.
(3) The measured volumetric flow is virtually unaffected by the fluid density, viscosity, temperature, pressure, and conductivity.
(4) Within the flow range, wide range of caliber.
(5) Corrosive fluids may be applied.
4.2.2 Disadvantages of Electromagnetic Flowmeters (1) Fluids with very low conductivity cannot be measured.
(2) Gas, steam, and liquids containing large bubbles cannot be measured.
(3) Cannot be used for higher temperature fluids.
4.3 Liner discussion of electromagnetic flowmeters The following lining materials are analyzed, discussed and selected based on the characteristics of the medium.
4.3.1 Neoprene (1) Main performance: 1 oil, solvent, oxidation resistance, resistance to general acid, alkali, salt and other media corrosion; 2 has excellent elasticity, wear resistance, but poor cold resistance.
(2) Scope of application: Non-acidic, strong alkali, strong oxidizing medium at 10°C~80°C; 2 Measurable sewage and mud.
4.3.2 Natural rubber (1) Main properties: 1 Better wear resistance, corrosion resistance, insulation and low temperature resistance. 2 poor oil resistance, poor aging resistance and oxidation resistance.
(2) Applicable range: -10°C～70°C Non-strong acid, strong alkali, strong oxidizing medium, suitable for drinking water.
4.3.3 Polyurethane rubber (1) Main properties: 1 It has excellent abrasion resistance and elasticity; 2 It has poor acid and alkali resistance.
(2) Scope of application: 1-25°C～60°C; 2 Neutral strong wear of pulp, coal slurry and mud.
4.3.4 Teflon (1) The main performance: 1 hydrophobic and non-sticky, strong high temperature resistance; 2 has excellent corrosion resistance, strong acid resistance, strong alkali, organic solvents and various salt solutions; 3 Good anti-vacuum capacity, high anti-negative pressure can add metal mesh, improve negative pressure resistance; 4 poor wear resistance.
(2) Scope of application: 1-25 °C ~ 140 °C non-strong wear medium; 2 sanitary media.
4.3.5 Polytetrafluoroethylene (1) Main properties: 1 is a kind of material with the most stable chemical properties in plastics. It is resistant to boiling hydrochloric acid, sulfuric acid, nitric acid, and aqua regia. It is also resistant to concentrated alkali and various organic solvents. Chlorine trifluoride, high temperature oxygen trifluoride, high flow rate of liquid chlorine, liquid chlorine, ozone corrosion; 2 poor wear resistance; 3 poor resistance to negative pressure.
(2) Scope of application: 1-25°C～140°C; 2 strong corrosive medium such as concentrated acid and alkali; 3 Hygienic medium.
4.3.6 Fluorinated Ethylene Propylene (3) Main properties: 1 Hydrophobicity and non-adhesion; 2 Corrosion resistance second only to Teflon; 3 Metal nets can be added to improve the negative pressure resistance when the negative pressure resistance is high. ; 4 poor wear resistance.
(4) Scope of application: 1-25°C～100°C non-strong wear medium; 2 Hygienic medium.
4.4 Problems encountered during application and methods for solving them Through the discussion of several types of lining materials mentioned above, it is not difficult to find that chloroprene rubber and natural rubber have a good wear resistance but poor corrosion resistance. Although Teflon, PTFE, and fluorinated ethylene propylene can meet alkali corrosion resistance, wear resistance is not very good. After repeated comparisons, the PTFE with the best stability was selected for trial operation to test the performance of the electromagnetic flowmeter.
The flowmeter was used for 2 to 3 months before it could not be used normally; to clarify the reason. After removing the electromagnetic flowmeter, it was found that there was no problem with the lining at the outlet of the electromagnetic flowmeter, but there was a detachment phenomenon from the measurement tube at the flanging of the flange outer lining material at the entrance. A gap appeared between the lining and the metal measuring tube, which caused the liquid to enter the gap, resulting in the meter not being used normally.
After clarifying the reasons for this problem, they communicated with the manufacturers and discussed with engineers and technicians. Decided to take two measures to solve this problem: 1 further optimize the control in the refining process, so that the solid particle diameter in the slurry to reduce the erosion of the electromagnetic flow meter at the entrance; 2 reduce the flow rate of slurry delivery; 3 A 2~3mm thick stainless steel gasket is added to the inlet of the electromagnetic flowmeter and the flange of the pipeline to reduce the erosion of the flanged lining material at the entrance flange of the electromagnetic flowmeter. Stainless steel gaskets can be changed regularly. After the above measures were taken, obvious results were achieved. After nearly two years of operation assessment, the electromagnetic flowmeter was stable in operation, accurate in measurement, and free from failure. Therefore, in this project, it is feasible to use electromagnetic flowmeters made of Teflon-lined materials for solids with higher solids content.
5 Concluding remarks As an instrument electrical professional engineer, how to better understand the situation of the process media, understand the characteristics and advantages and disadvantages of each type of flowmeter itself, and discover the problems that may arise in some projects, and the ability to solve problems is our Constant work should be improved. The improvement of the conditions for the use of electromagnetic flowmeters is a useful attempt, and it also increases our awareness of innovation.
Soundproof Genset,Generating Set,Diesel Electric Genset
Oripo Power Engineering Co., Ltd. , http://www.fsgeneratores.com