Pulverized coal combustion boiler

Abstract

A pulverized coal combustion boiler 100 comprising: a furnace 50; a plurality of burners 6 for supplying and burning pulverized coal fuel in the furnace arranged at positions of a plurality of stages having different heights on a furnace front wall 51 and a furnace rear wall 52 of furnace wall surfaces forming the furnace 50, the furnace rear wall 52 arranged for facing the furnace front wall 51; a plurality of mills 2 arranged for supplying the pulverized coal fuel to the plurality of burners 6 arranged at each of the plurality of stages; and pulverized fuel pipes 5 arranged for distributing and supplying the pulverized coal to the plurality of burners 6 at each of the stages of the furnace front wall 51 and the furnace rear wall 52 from each of the plurality of mills 2.

Description

CLAIM OF PRIORITY[0001]The present application claims priority from Japanese application serial No. 2006-342414, filed on Dec. 20, 2006, and Japanese application serial No. 2006-351536, filed on Dec. 27, 2006, the contents of which are hereby incorporated by reference into this application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a pulverized coal combustion boiler to burn pulverized coal.[0004]2. Description of Related Art[0005]In a conventional pulverized coal combustion boiler as shown in Japanese Application Patent Laid-Open Publication No. 2001-221406, one mill that produces and supplies pulverized coal is disposed on each of three burner stages (upper stage, middle stage, and lower stage) arranged on a furnace front wall and a furnace rear wall that constitute a furnace (six mill total).[0006]The feed rate of supplying coal to the boiler is reduced to lower the heat output in the furnace when the pulverized coal combustio...

AI Technical Summary

Benefits of technology

[0022]The arrangement of opposed burners at the water wall pipes of the furnace front wall and the furnace rear wall of the once-through boiler is excellent in ensuring the combustion performance in a wide load range because of the configuration that is advantageous for the stable retention of the combustion flames by the burners alone. However, because of the imbalance problem of the generated vapor temperatures, the application of the combustion method in which the opposed burners are arranged at the water wall pipes of the furnace front wall and the furnace rear wall of the furnace is difficult when the water walls of the once-through boiler furnace are formed with vertically arranged water wall pipes.

[0023]A first object of the present invention is to provide a pulverized coal combustion boiler for leveling heat loads of the plurality of water pipes constitute the furnace wall surfaces of the furnace in the entire load range to control the thermal stress generated in the furnace water pipes, enhancing safety of the furnace wall surfaces and extending life of the pulverized coal combustion boiler.

[0024]A second object of the present invention is to provide a pulverized coal combustion boiler having opposed burners placed at the water pipes vertically arranged on the furnace front wall and the furnace rear wall for making the heat loads in the furnace uniform to control an increase in the pipe wall temperatures of the water pipes of the furnace.

Problems solved by technology

This results in a substantial difference in the heat absorbing balance between the furnace front wall and the furnace rear wall.

As a result, the fluid temperature of water pipe outlets provided in the plurality of water pipe walls that constitute the furnace wall surfaces of the furnace front wall and the surface rear wall becomes imbalanced and the elongation of the water pipes are varied so that the thermal stress is generated on the furnace wall surfaces, which may damage the furnace wall surfaces.

This is reflected in the fluid temperature of the outlets of the water wall pipes of the furnace, causing imbalanced temperatures of the vapor generated in the water wall pipes.

Images