Method for calibrating secondary air volume of coal-fired boiler on line

Abstract

A method for calibrating a secondary air volume of a coal-fired boiler on line comprises the following steps: performing an adjustment experiment on each secondary air volume in turns under a certain stable load point, and establishing a multivariate linear equation set through a balance relationship between experimental data and a total air volume of the boiler; obtaining a flow coefficient of each secondary air volume measuring device by solving the equation set; and during measurement of an actual air volume, obtaining an accurate air amount through the calculated flow coefficient, thus achieving the online calibration of the secondary air volume. According to the online calibration method, the shutdown of the boiler is not required and the secondary air volume adjust experiment can be performed in a stable load section in the running process of the boiler at any time, so that the normal operation of the boiler is basically not affected and the loss caused by the shutdown and the startup of the boiler can be avoided; additional measuring equipment is not required to be installed inside and detached from an air duct of the boiler; the calibration process is simple; equipment and human resources are saved; and the calibration cost is far lower than that in the conventional calibration method.

Description

technical field [0001] The invention relates to a method for accurately calibrating the secondary air volume of a coal-fired boiler under normal operating conditions, and belongs to the technical field of boilers. Background technique [0002] The wind-to-coal ratio in boiler technology largely determines the efficiency of coal-fired boilers. When the air volume is too large, the boiler exhaust loss is too large, resulting in a decrease in boiler efficiency; when the air volume is too small, the boiler’s incomplete combustion loss is too large, which will also lead to a decrease in boiler efficiency. There is an optimal air-to-coal ratio for coal-fired boilers. The concept of excess air coefficient is used in engineering to describe this concept. The physical meaning of excess air coefficient is the ratio of the actual amount of dry air sent into the boiler furnace to the theoretical air amount required for the complete combustion of coal fed into the furnace. There is a de...

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Problems solved by technology

The calibration accuracy of this method is not very high due to the lack of straight pipe sections on site, errors in the installation of pitot tube groups or flute tube groups, uneven wind flow, and differences in wind flow characteristics under cold and hot conditions.

In addition, the on-site working site is narrow and the conditions are harsh. It is very troublesome to install and remove the wind speed measurement device, the experiment time is long, and the calibration cost is high.