Method for controlling opening degree of primary air door at inlet of coal mill

Abstract

The invention discloses a coal mill inlet primary air door opening degree control method which comprises the following steps that the pressure of a hot primary air mother pipe and the coal feeding amount of a coal mill are kept unchanged, and a primary air door opening degree-primary air volume characteristic curve under the current pressure of the hot primary air mother pipe and the resistance of a primary air duct system is obtained through experimental testing; solid modeling is conducted according to the primary air duct and the primary air door structure, numerical simulation is conducted on the model, and the characteristics of the primary air door opening degree-primary air volume at the inlet of the coal mill under the hot primary air mother pipe pressure and the primary air duct system resistance under the test working condition are obtained; calculating a primary air door opening-primary air volume characteristic curve under different hot primary air mother pipe pressures and primary air duct system resistances by adopting numerical simulation; and according to the actual operation parameters, a corresponding primary air door opening-primary air volume characteristic curve is matched, and the primary air door opening is obtained according to the air volume demand value. The method is suitable for the situation that the air duct resistance of the actual coal mill is complex and changeable, the conception is ingenious, and the air door can be rapidly and accurately controlled.

Description

technical field [0001] The invention belongs to the technical field of automatic control of thermal power plants, and in particular relates to a method for controlling the opening of a primary damper at the inlet of a coal mill. Background technique [0002] The primary damper opening control method at the entrance of the coal mill is mainly feedback adjustment, that is, the primary damper opening is adjusted according to the difference between the primary air volume demand value and the current primary air volume actual value, and the primary damper opening is increased or decreased by opening or closing the primary air volume. Reduce the primary air volume so that the actual value of the primary air volume matches the demand value of the primary air volume. However, this feedback adjustment method needs to constantly compare the demand value of the primary air volume with the actual value of the current primary air volume, so that the damper adjustment has disadvantages su...

AI Technical Summary

Problems solved by technology

However, this feedback adjustment method needs to continuously compare the demand value of the primary air volume with the actual value of the current primary air volume, so that the damper adjustment has disadvantages such as slow response, large fluctuations, and large deviations, making it difficult to achieve fast and accurate control of the damper

The poor linearity of the primary air volume control will cause the primary air volume of the coal mill to fail to follow the change of coal volume in a timely and accurate manner. Too large or too small primary air volume will cause problems such as increased NOx emission concentration, coal mill blockage, and high CO emission concentration.

[0003] At present, domestic and foreign scholars' research on the primary damper at the entrance of the coal mill mainly focuses on the airtightness of the damper structure and the flexibility of adjustment. There is little research on the control method of the damper opening, and the adjustment response of the primary damper is slow, fluctuating, and large deviation. The problem has long plagued power plant operators

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