New method for reducing exhaust gas temperature of coal-fired boiler

Abstract

The invention relates to a new method for reducing the exhaust gas temperature of a coal-fired boiler. A pipeline adopted for the method comprises a high-temperature section air preheater, a medium-temperature section air preheater and a low-temperature section air preheater; the method comprises that connecting air duct are drawn out from the pipes of the two end outlets of the high-temperature section air preheater to the pipe of the outlet of a primary air box, respectively, the previous primary warm air powder feeding is changed into hot air powder feeding, connecting air duct regulating valves are mounted on the two connecting air ducts, air box outlet regulating valves are mounted on the pipes of the two end outlets of the primary air box for controlling the temperatures, and the effective sectional area of the connecting air ducts is equal to the sectional rear of the pipes of the outlets of the primary air box. The new method is characterized in that the previous primary warm air powder feeding is changed into hot air powder feeding so that the heat absorption capacity of the exhaust gas is improved, the exhaust gas temperature of the heated surface of the tail of the boiler is reduced and the low-load stable combustion capacity of the boiler is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of primary air-temperature air-feeding pulverized coal-fired boilers, in particular to a new method for reducing the exhaust gas temperature of coal-fired boilers. Background technique [0002] At present, in the design of coal-fired boilers in power plants, such as figure 1 As shown, the structural principle of the current hot air connecting pipeline is given. The heat released on the flue gas side of the air preheater includes the heat exchange between the extracted 30% warm air and the flue gas on the heating surface of the high temperature section. In actual operation This part of the heat of the flue gas is not absorbed by 30% of the warm air, so the actual operating exhaust gas temperature is about 30°C higher than the design value; due to the impact of the coal market in recent years, the coal used by the power plant deviates from the design value Larger, especially the low volatile content of coal, ...

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Problems solved by technology

[0002] At present, in the design of coal-fired boilers in power plants, such as figure 1 As shown, the structural principle of the current hot air connecting pipeline is given. The heat released on the flue gas side of the air preheater includes the heat exchange between the extracted 30% warm air and the flue gas on the heating surface of the high temperature section. In actual operation This part of the heat of the flue gas is not absorbed by 30% of the warm air, so the actual operating exhaust gas temperature is about 30°C higher than the design value; due to the impact of the coal market in recent years, the coal used by the power plant deviates from the design value Larger, especially the low volatile content of coal, the original warm air powder feeding is no longer suitable for existing coal types, which seriously affects the economic operation of the boiler;

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