Method and system for measuring primary air flow at inlet of coal mill

Abstract

The invention discloses a method and system for measuring the primary air flow of an inlet of a coal mill. The method comprises the following steps that the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow before mixing and the primary air temperature of the inlet of the coal mill after mixing are obtained; the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing are obtained through the obtained cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow before mixing and the primary air temperature at an inlet of the coal mill after mixing, and then the cold primary air flow before mixing is obtained; and the primary air flow of the inlet of the coal mill is obtained through the hot primary air flow before mixing and the cold primary air flow before mixing. The measuring method can accurately obtain the primary air flow of the inlet of the coal mill.

Description

technical field [0001] The invention belongs to the technical field of boilers, and relates to a method and a system for measuring the primary air flow at the inlet of a coal mill. Background technique [0002] The direct blowing pulverizing system is a pulverizing system widely used in thermal power plants at present. For the direct blowing pulverizing system, the primary air flow at the inlet of the pulverizer is a key parameter for the adjustment of the pulverizing system, and it is also an important factor in the automatic control of the boiler. in accordance with. Accurately measuring the primary air flow at the inlet of the coal mill is beneficial to accurately control the coal mill inlet air ratio, stabilize the combustion in the furnace, adjust the center of the flame in the furnace, and protect the burner nozzle, which is very important for the safe, stable and economical operation of the boiler. significance. [0003] Due to the compact layout of thermal power pl...

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Problems solved by technology

[0003] Due to the compact layout of the thermal power plant, the inlet space of the coal mill is small, and the cold primary air usually enters the hot primary air pipe from the side or top of the hot primary air pipe, and the mixed hot primary air is closer to the coal mill inlet , there are not enough straight pipe sections for mixing, resulting in uneven primary air flow field in the air duct at the inlet of the coal mill after mixing

The current measurement of the primary air flow at the inlet of the coal mill after mixing is usually directly measured by the air volume measuring device arranged in the air duct at the inlet of the coal mill. Due to the uneven flow field and local eddy currents at this position, the measured primary air flow There is a deviation from the actual primary air flow, and the deviation changes irregularly with the opening of the hot and cold air doors, which leads to the inability to accurately control the primary air flow at the coal mill inlet

In the prior art, disturbance devices or rectifying grids are usually installed in the mixed pipeline to improve the uniformity of the mixed flow field, and the air volume measurement device installed in the inlet air duct of the coal mill directly measures the mixed primary flow rate. However, due to the small space at the inlet of the coal mill and many elbows, the temperature field in the air duct can be improved by adding a disturbance device or a rectifying grille, but the flow field is still not uniform enough, resulting in measurement results that still cannot meet the requirements of the project. Require

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