System and method for monitoring oxygen at furnace exit of circulating fluidized bed boiler

Abstract

The invention discloses a system and method for monitoring oxygen at the furnace exit of a circulating fluidized bed boiler. The system comprises a coal feeding quantity detecting device used for detecting the quantity of coal entering the boiler from a furnace entrance, an air volume detecting device used for detecting the total air volume supplied to the boiler, a coal calorific value measuring device used for measuring the calorific value of the coal fed into the boiler, and a data processing device used for figuring out the oxygen at the furnace exit by utilization of the coal feeding quantity, the total air volume and the calorific value of the coal, so as to perform accurate and well dynamic monitoring on the oxygen at the furnace exit.

Description

technical field [0001] The invention relates to a monitoring system and a monitoring method for the oxygen amount at the furnace outlet of a boiler, in particular to a monitoring system and a monitoring method for the oxygen amount at the furnace outlet of a circulating fluidized bed boiler. Background technique [0002] The oxygen content of the flue gas (that is, the oxygen content at the furnace outlet) is an important thermal parameter for power plants to save energy and maintain the economical combustion of boilers. It has a functional relationship with the excess air coefficient, which directly reflects the air-to-coal ratio of the boiler combustion process. , which is of great significance to combustion economy. If the oxygen content in flue gas is too high or too low, energy will be wasted, so it should be limited within a reasonable range. [0003] At present, the oxygen sensors for measuring the oxygen content of boiler flue gas are mainly thermomagnetic oxygen se...

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Problems solved by technology

[0004] (1) The failure rate is high, and the main failures include fly ash wear, ash blocking, platinum electrode poisoning or peeling off, electric heater damage, etc.

[0005] (2) The measurement accuracy is low. Due to the accuracy of the sensor itself, the uneven distribution of flue gas oxygen, and the influence of air leakage at the installation site, the measurement accuracy is not easy to guarantee, and the comprehensive error is large.

[0006] (3) The dynamic characteristics are poor. The zirconia oxygen meter works on the principle of a concentration cell. Oxygen molecules have a permeation process in the zirconia dielectric, which causes a hysteresis in measurement; at the same time, in order to reduce fly ash wear, Many oxygen meter probes are equipped with ceramic protective sleeves, but this increases the possibility of dust blocking and the hysteresis of measurement

[0007] (4) Difficulty in overhaul, maintenance and calibration

[0008] In addition, there are many disadvantages such as high cost, slow response speed, unfavorable online monitoring of the process and feedback signals required for online closed-loop control.

[0009] Therefore, it is impossible to accurately and dynamically monitor the oxygen amount at the furnace outlet

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