Application of Microwave Solid Flow Meter in Detection of Pulverized Coal

Abstract: The application information of microwave solid flow meter in pulverized coal detection is provided by excellent flow meter and flow meter manufacturers and quotation manufacturers. Abstract: Flowmeters are widely used in many flow measurement. This paper mainly introduces a microwave solid flowmeter and its application in flow measurement. 1. Introduction Large coal-fired units in thermal power plants generally use direct-blown pulverizing systems, each mill. For more flowmeter manufacturers to select models and price quotations, you are welcome to inquire. The following is the application article details of microwave solid flowmeters in pulverized coal detection. Flowmeters are widely used in many flow measurement. This paper mainly introduces a microwave solid flowmeter and its application in flow measurement. 1. Introduction Large-scale coal-fired units in thermal power plants generally use a direct-blown pulverizing system. Each coal mill outlet has 4 to 8 primary air pulverized coal pipes directly connected to the boiler burner, and pulverized coal passes through the pulverized powder pipeline. sent to the boiler burner for combustion. Due to the different lengths and the number of elbows of each pulverized coal pipeline, the pressure loss of each pipeline is different, resulting in uneven distribution of pulverized coal among the pulverized coal pipelines, resulting in the burner not being able to operate under the optimal air-to-coal ratio condition. Normal operation reduces combustion efficiency, increases NOX emissions and increases boiler failure rates. 2. Analysis of problems in pulverized coal detection When the pulverized coal distribution between the pulverized coal pipelines is uneven, the pulverized coal concentration will be too high, too low, and the flow rate will be too high or too low. When the pulverized coal concentration is too high, the following situations will occur: pulverized coal blocks the pipe, cannot transport pulverized coal to the furnace, and at the same time causes the pulverized coal in the pipeline to spontaneously combust and burn out the pulverized coal transportation pipe; the pulverized coal combustion is incomplete, the efficiency is low, and the CO increases. Large, aggravate the high temperature corrosion of the heating surface in the furnace and the heating surface of the superheater; the local slagging of the furnace and the superheater will seriously affect the normal operation of the boiler. When the pulverized coal concentration is too low, the following conditions will occur: the furnace temperature is reduced, it is easy to flame out, the pressure of the boiler is reduced, and the load requirements cannot be met; a large amount of NOX is generated, the environment is polluted, the superheater is high temperature, and even the superheater burst and other accidents; Atmospheric pressure, increase the flow rate of primary air (powder conveying pipe), the tangential circle of the furnace is offset from the center of the furnace, causing local slagging on the furnace wall, excessive smoke temperature deviation on the heating surface at the tail, and even tube bursting. When the flow rate of the mixture of pulverized coal and air is too fast, it will affect the optimal concentration of pulverized coal, and the following conditions will occur: aggravate the wear of the powder pipe; the mixture flow rate at the burner outlet is too fast, and the combustion lags, causing the center of the flame to be skewed and easy to cause Partial coking on the furnace wall and partial overheating of the superheater at the end of the furnace; incomplete combustion, increased carbon content in the ash and increased flue gas temperature, reducing boiler efficiency. When the flow rate of the mixture is too slow, in addition to affecting the optimal pulverized coal concentration, the following conditions will occur: the amount of pulverized coal deposited in the pulverized coal pipeline increases, causing pipe blockage; causing pulverized coal spontaneous combustion, or even pulverized coal pipeline explosion; the flow rate of the mixture at the burner outlet If it is too slow, a large amount of pulverized coal will be separated from the main air flow, and the long-term removal will increase the coal consumption, and will also cause the furnace to flame out and the secondary combustion to block the ash outlet at the lower part of the boiler. 3. Pulverized coal measurement solution The method to solve the above problems is to measure the flow rate and mass flow of pulverized coal in the pulverized coal pipe online, and adjust the secondary air volume of each burner as a reference to meet the best combustion conditions. In the direct-blown pulverizing system, the control of pulverized coal volume is monitored by the primary air volume entering the boiler pulverizer. Therefore, the primary air flow signal is particularly important. For the flow rate measured by the Venturi tube flow, when the front and rear flow fields are stable and uniform, the flow coefficient K is a constant, and the ventilation rate can be obtained only by measuring the fluid density and pressure difference. Due to the constraints of the working environment and equipment conditions, the differential pressure signal is distorted, the coefficient K is not constant, and the maximum deviation is more than 34%. Therefore, it is unreliable to adjust the air volume through the baffle to control the amount of coal entering the boiler. When the boiler load increases or decreases, the stoker can only adjust the air coal by relying on the on-site experience and the detected reference air volume. If the online measuring instrument for the flow and concentration of pulverized coal is installed in the powder conveying pipe (ie the primary air duct), the amount of pulverized coal can be optimally controlled, coal consumption can be reduced, the labor intensity of the stokers can be reduced, and the working environment can be improved. For the direct-blown pulverizing system, installing an on-line measurement device for the flow and speed of pulverized coal on the primary air duct can not only solve the above-mentioned problems of large error and unreliability in the measurement of the air volume of the two-in-two-out pulverizer, but also timely detect the direct flow and speed of the pulverized coal. The air lock of the blowing separator leaks and does not work.

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