electromagnetic flow meter suppliers

electromagnetic flow meter supplier

The gasification device adopts GE coal-water slurry pressurized gasification technology. This technology adopts a single burner design on the top of the gasifier. 60% of the coal-water slurry and high-pressure oxygen are burned into the furnace through the burner. The furnace temperature is 1200℃～1300℃. The synthesis gas generated by the combustion reaction enters the chill chamber water bath along the downcomer, and then exits the gasifier along the ascending pipe through the baffle and enters the downstream evolution device for processing. At the same time, the black water produced by the system is sent to the flash evaporation system, flash steam and heat recovery are achieved through flash evaporation and sedimentation, the gray water is recycled and reused to achieve the purpose of energy saving and consumption reduction, and the generated slag and fine slag are sent out of the boundary.
   The gasification device has high pressure, high temperature, serious medium erosion, strong corrosiveness, severe working conditions, and frequent instrument equipment failures. Due to the original selection and material of some instruments and equipment, the risks of leakage, internal leakage, high pressure and low pressure of syngas and other flammable and explosive media are relatively high. Technical research on key equipment with frequent failures of the gasification device is a guarantee The necessary conditions for the long-term stability of the gasifier.
 1 Difficult problems and solutions existing in the actual operation of the gasification unit
   1) Due to the special physical characteristics of coal water slurry, it is very difficult to measure. It contains about 65% of extremely fine coal solid particles, plus auxiliary additives. Under high pressure conditions, the lining of the electromagnetic flowmeter sensor and the measuring tube are required due to the extrusion of the medium on the lining and the scouring environment of the electrode. The adhesion performance of the electrode and the anti-noise and anti-leakage performance of the electrode have high requirements, and the coal water slurry is a non-Newtonian fluid with complex composition, difficult measurement and corrosiveness. According to the coal slurry flow measurement experience in the same industry, most of the coal slurry flowmeters in the Texaco gasifier in the current coal chemical industry are designed and selected using electromagnetic flowmeters, but the actual use effects are very different. This issue has always been a difficult problem discussed by professionals in the coal chemical industry.
   2) The synthesis gas temperature at the outlet of the gasifier was originally designed to be three thermal resistances in the same casing, three out of two interlocking stops. Due to the large vibration and temperature fluctuation of the synthesis gas pipeline at the outlet of the gasifier, the gasifier shutdown accident, so in order to avoid such accidents, the temperature of the synthesis gas at the outlet of the gasifier needs to be modified and optimized.
   3) The medium of the black water flow control valve of the slag pool pump of the gasification device is the black water of the gasifier, which has strong scouring and corrosive effects on metal materials, and frequent perforation of the valve body and inner valve of the instrument control valve in use For destructive failures of parts, the valve's average failure-free period is only about 45 days, and valve maintenance costs are high, which affects the long-term operation of the gasifier.
 2 Solutions to the failure of the gasification unit
 2.1 According to the gasifier's mixed combustion conditions and the characteristics of coal water slurry, how to solve the problem of coal slurry flow measurement, so as to provide a guarantee for the stable, long-lasting and optimal operation of the gasifier
   The gasifier uses 60% coal-water slurry and high-pressure oxygen for combustion. The medium composition of the coal-water slurry is complex, the pulsating signal is strong, and the measurement is difficult. Under such complex working conditions, the preferred measurement method in the industry is the electromagnetic flowmeter. Although the electromagnetic flowmeter meets the measurement requirements of the coal water slurry flow of the gasification device most of the time, there are still many problems. After many years of use, the summary Some methods have been proposed to improve the stable operation of electromagnetic flowmeters.
   The coal-water slurry electromagnetic flowmeter is a very critical measurement device for the gasification device. First, the gasifier coal-water slurry electromagnetic flowmeter takes three intermediate values to participate in the oxygen-to-coal ratio control, and then the gasifier coal-water slurry electromagnetic flowmeter takes two from three to participate. The gasifier is shut down by interlocking logic. Therefore, higher requirements are put forward for the timeliness, accuracy, and stability of the measurement of the coal water slurry electromagnetic flowmeter. These performance indicators are also key considerations when selecting models.
 2.1.1 The main problems existing in the electromagnetic flowmeter of coal water slurry
 1) Severe distortion of the measured value
   In the actual normal operation of the gasifier, the CWM electromagnetic flowmeter often has large deviations between the actual value and the measured value, zero drift, large fluctuations and other measured value distortion phenomena. Problems such as fluctuations and unstable measurement values of the CWS electromagnetic flowmeter will directly affect the normal operation of the gasifier. Due to this problem, accidents of the gasifier shutdown have been caused by mistake.
 2) The measurement response speed to the actual flow change is slow
   The gasifier has higher requirements for the timeliness of the coal water slurry flow measurement, because it is related to the normal and safe operation of the gasifier. By collecting the measurement data during the actual operation of the gasifier coal-water slurry electromagnetic flowmeter, after analysis, it is found that the change of the measured value of the coal-water slurry electromagnetic flowmeter lags behind the actual flow change by about 25s when the actual disturbance occurs. . This means that when the actual flow of coal water slurry decreases, the measured value does not reflect the change in the actual decrease in time and quickly. This phenomenon is more terrible, because under the control strategy of a fixed oxygen-to-coal ratio, the measured value of the coal slurry flow does not change during the lag time, so the oxygen flow will not change, and the actual coal slurry flow has been reduced. It may cause over-oxygen in the gasifier, and in serious cases, there may be a safety hazard of explosion.
 3) Measurement disturbance caused by coal slurry quality
   The measuring medium of the coal slurry flowmeter of the gasification unit is coal water slurry, sludge-containing wastewater, and MTO waste lye. The ordinary flowmeter is affected by the impact of solid particles in the coal water slurry on the electrode, oil film interference, and floc interference. Pulse and noise interference are generated, and the fluctuation is relatively large. At the same time, the flow of coal water slurry participates in the calculation of the oxygen-to-coal ratio and locks and stops, which affects the long-period stable operation of the gasifier.
 2.1.2 In view of the problems of the above coal water slurry electromagnetic flowmeter, analyze the causes and propose solutions
   There are many reasons for the measurement value distortion and the slow response speed of the electromagnetic flowmeter when measuring coal water slurry, such as: installation does not meet the specifications, grounding does not meet the requirements, unreasonable parameter settings, high pressure coal slurry pump (reciprocating pump) against coal The influence of slurry flow measurement, the influence of blending conditions on coal slurry flow measurement, the change of coal slurry composition, etc. The main reasons that affect the flow measurement of coal water slurry are analyzed as follows:
 1) Electromagnetic interference
   There are many large motors with moving equipment in the high-pressure coal slurry pump workshop. The operation of the motor will release a large amount of electromagnetic signals. The electromagnetic flowmeter is very sensitive to the surrounding electromagnetic signals, because the measurement signal of the electromagnetic flowmeter is very weak, generally only 2.5mV~ 8mV. Therefore, to the requirements of the electromagnetic flowmeter, the working ground must be reliable and firm, and meet the requirements of the grounding specification.
 2) High pressure coal slurry pump
   The stability of the high-pressure coal slurry pump has a great influence on the measurement of coal slurry flow. Because the high-pressure coal slurry pump is a reciprocating pump, the coal slurry fluid presents a regular pulsating flow during normal operation, with small pulsation and easy filtration. When the high-pressure coal slurry pump malfunctions, the coal slurry fluid will fluctuate greatly, and the pulsating flow will cause large fluctuations in the measured value of the coal slurry flow. Therefore, during the normal operation of the high-pressure coal slurry pump, timely inspections should be conducted to deal with abnormalities in time.
 3) Composition of coal slurry
   The mixed combustion of sludge water in the gasifier causes the composition of the coal slurry to be more complex. The coal water slurry containing sludge water is acidic. The acidic coal water slurry is highly corrosive to the electromagnetic flowmeter, which will affect the flow rate of the coal slurry. The measurement has a great impact; the air bubbles in the coal water slurry are also a factor that cannot be ignored in the electromagnetic flowmeter measurement; the coal water slurry is a fluid with a high solid content, and the noise generated by the solid particles hitting the electrode is expressed as the coal slurry flow rate. Fluctuations in measured values. The solution is as follows:
   ① Put forward requirements for the electrode of the electromagnetic flowmeter. The use of a smooth electrode with a small surface area can greatly reduce the frequency of particles hitting the electrode, and the surface of the electrode will not be easily scratched.
   ② Use the new low-noise noise shielding technology, and use molecular-grade ceramic isolation sensors on the electrode surface to effectively shield measurement noise such as iron filings, oil films, bubbles, flocs, and particle impacts. Practice has proved that the use of low-noise electrode measurement results is better.