Method for feeding pulverized coal in power station pulverized-coal fired boiler

Abstract

The invention relates to a method for feeding pulverized coal in a power station pulverized-coal fired boiler. The conventional method for feeding the pulverized coal has various drawbacks. The method comprises the following steps of: extracting 5 to 15 percent of the total smoke gas in a flue between a low temperature superheater and a coal economizer of a power station pulverized-coal fired boiler system, and taking the smoke gas as the smoke gas for feeding the pulverized coal; mixing 5 to 20 percent of water vapor with the smoke gas for feeding the pulverized coal to form mixed gas for feeding the pulverized coal; heating the mixed gas for feeding the pulverized coal to the temperature of between 800 and 1000 DEG C; feeding the pulverized coal with the density of 0.8 to 2kg / kg into a burner of the power station pulverized-coal fired boiler by using the heated mixed gas for feeding the pulverized coal; and keeping the airflow temperature of the mixed gas for feeding the pulverized coal between 800 and 1000 DEG C in the process of feeding the pulverized coal. The method has high primary air pulverized coal airflow density, can effectively reduce ignition heat of the pulverized coal airflow, saves energy by using partial waste heat of the smoke gas at the tail of a boiler, and improves thermal energy utilization efficiency.

Description

technical field [0001] The invention relates to a pulverized coal boiler powder feeding method in a power station, in particular to a powder feeding method that can significantly reduce the ignition of the pulverized coal air flow and utilize high-temperature flue gas with low oxygen content at the tail of the boiler furnace. technical background [0002] In the process of start-up and shutdown of power plant boilers and low-load stable combustion, it is necessary to find ways to reduce the ignition heat of the pulverized coal airflow, so as to achieve the purpose of rapid ignition of pulverized coal and stable combustion. [0003] For power plants, in the case of specific coal types and coal powder particle size distribution, commonly used methods to reduce ignition heat: 1. Hot air powder feeding: use hot air with a temperature of about 300°C to feed powder, but the temperature should not be too high , otherwise it will cause the pulverized coal to burn in advance in the p...

AI Technical Summary

Problems solved by technology

[0003] For power plants, in the case of specific coal types and coal powder particle size distribution, commonly used methods to reduce ignition heat: 1. Hot air powder feeding: use hot air with a temperature of about 300°C to feed powder, but the temperature should not be too high , otherwise it will cause the pulverized coal to burn in advance in the powder feeding pipeline, causing accidents; 2. Increase the concentration of pulverized coal: the normal primary air powder feeding concentration is about 0.6kg / kg, too high a concentration will easily cause the pulverized coal to deposit and block the powder feeding pipe Therefore, a thick-thin separation device is often added inside the burner to divide the pulverized coal concentration into two streams, the dense-phase pulverized-coal flow is ignited first, and then the entire pulverized-coal flow is ignited. The increase of the thick-thin separation device complicates the structure of the burner; 3. Adding flammable gas: Studies have shown that the addition of a small amount of flammable gas can significantly reduce the heat of ignition of the pulverized coal flow. Therefore, some researchers use water electrolysis to generate Brown gas for powder feeding, or put the gas on the coal gasification device Coal gas is introduced into the pilot burner to reduce the heat of ignition, both of which require additional water electrolysis or coal gasification