System for improving outlet temperature adjustment flexibility of coal mill

Abstract

The invention discloses a system for improving the flexibility of outlet temperature adjustment of a coal mill. The system comprises a primary air fan (1), an air preheater (2), the coal mill (3) anda bypass cold air pipeline (4), wherein the outlet of the primary air fan (1) is divided into two paths, one path is communicated with the inlet of the coal mill (3), the other path is communicated with the inlet of the air preheater (2), the outlet of the air preheater (2) is communicated with the inlet of the coal mill (3), and the bypass cold air pipeline (4) is communicated between the inlet and the outlet of the air preheater (2). The bypass air pipelines are additionally arranged on the front pipeline and the rear pipeline of the primary hot air side of an original air preheater, so thatthe primary air volume entering the air preheater for heating is adjustable, when the moisture of coal for actual combustion is low, the primary air volume entering the air preheater is reduced through the arranged bypass air channels, the primary air-hot air ratio of the inlet of the coal mill is reduced, and the outlet temperature of the primary air-powder mixture is ensured to meet the designrequirement.

Description

technical field [0001] The invention belongs to the technical field of pulverizing systems for coal-fired boilers, and in particular relates to a system for improving the flexibility of adjusting the outlet temperature of coal mills. Background technique [0002] Coal quality characteristics have an important impact on the safety, economy and environmental protection characteristics of boiler combustion. At present, subject to the continuous consumption of coal resources and fluctuations in the coal market, and in order to better control the cost of power generation, the quality of incoming coal for major power plants is constantly changing, and many power plants use coal of mixed quality and source The actual coal quality deviates from the design check coal quality. The change of coal quality directly leads to the change of the combustion characteristics of the boiler, which brings great hidden dangers to the safe and stable operation of the unit. [0003] For most of the...

AI Technical Summary

Problems solved by technology

However, there is still no effective solution and method for the situation that the design coal has high moisture content (such as lignite) and the actual combustion coal has low moisture content (such as bituminous coal).

For coal with high moisture content, the proportion of hot air in the primary air is designed to be higher, that is, the corresponding hot air pipes are thicker and the cold air pipes are thinner. When a large proportion of boilers are mixed with low-moisture coal, the required amount of hot air is greatly reduced. In this case, even if the original cold air duct adjustment door is fully opened, the temperature of the primary hot air at the coal mill inlet is still high, and the hot air volume is still too large, which eventually leads to the coal mill outlet air being mixed with low-moisture coal. The temperature of the powder mixture exceeds the design requirement, which seriously affects the safety of the unit operation

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