CN201715533U - Powder feeding device of pulverized coal boiler at power station - Google Patents

Abstract

The utility model relates to a powder feeding device for a pulverized coal boiler of a power station. Existing devices have deficiencies in reducing ignition heat. The utility model comprises a powder bin and a powder feeding airflow pipe, the inlet end of the powder feeding airflow pipe communicates with the flue between the low-temperature superheater and the economizer of the pulverized coal boiler system of the power station, and the outlet end connects with the combustion chamber of the pulverized coal boiler system of the power station. The powder outlet of the powder bin is connected with the powder feeding air pipe through the powder feeder, and the powder feeding air pipe is provided with a regulating valve and a circulating fan, and a section of the powder feeding air pipe between the regulating valve and the circulating fan is connected with an adjacent The high-temperature flue gas pipeline and steam pipeline of the furnace; the powder feeding airflow tube between the circulating fan and the outlet end is equipped with an external heating device. The utility model has a simple structure, can effectively reduce the ignition heat of the pulverized coal airflow, and utilizes part of the waste heat of the flue gas at the tail of the boiler to improve the heat energy utilization efficiency.

Description

A pulverized coal boiler powder feeding device for a power station

technical field

The utility model relates to a pulverized coal boiler powder feeding device of a power station, which is suitable for boilers using pulverized coal as fuel.

technical background

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.

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.

Contents of the invention

The purpose of the utility model is to provide a power plant pulverized coal boiler powder feeding device that can effectively reduce the fire heat in view of the deficiencies in the prior art.

The utility model comprises a powder bin and a powder feeding airflow pipe, the inlet end of the powder feeding airflow pipe communicates with the flue between the low-temperature superheater and the economizer of the pulverized coal boiler system of the power station, and the outlet end connects with the combustion chamber of the pulverized coal boiler system of the power station. The powder outlet of the powder bin is connected with the powder feeding air pipe through the powder feeder, and the powder feeding air pipe is equipped with a regulating valve and a circulation fan, and the circulation fan is set at the connection between the powder feeding air pipe and the powder feeder and at the entrance On the powder feeding air pipe between the two ends, the regulating valve is set on the powder feeding air pipe between the circulating fan and the inlet end, and the powder feeding air pipe between the regulating valve and the circulating fan is connected with the high temperature flue gas pipe of the adjacent furnace Road and steam pipeline; the powder feeding airflow tube between the circulating fan and the outlet is provided with an external heating device.

The high-temperature flue gas pipeline of the adjacent furnace communicates with the flue between the low-temperature superheater and the economizer of the pulverized coal boiler system of the adjacent furnace power station; the steam pipeline communicates with the medium-pressure steam pipeline of the utility station of the power plant .

The external heating device is a resistance heating device or an intermediate frequency heating device sleeved outside the pipeline.

The utility model has a simple structure, and can use the high-temperature flue gas produced by the pulverized coal boiler system of the power station to increase the concentration of the pulverized coal airflow in the primary air to 0.8-2kg/kg, effectively reducing the ignition heat of the pulverized coal airflow. During this process, the pulverized coal airflow enters the burner before it is ignited to generate pyrolysis, and part of the volatile matter is precipitated, and _CO2 , _H2O , _O2 and other gases in the powder feeding airflow are partially gasified with coal char to generate CO , H ₂ and other flammable gases can also effectively reduce the ignition heat of pulverized coal airflow. The reaction equation is as follows:

C+H ₂ O→CO+H ₂ -135kJ

2C+O ₂ →2CO+221kJ

C+CO ₂ →2CO-170kJ

Due to the large amount of volatile matter precipitation, the pore area on the surface of the pulverized coal particles is greatly increased, which increases the reaction area between the pulverized coal surface and oxygen, and makes the pulverized coal flow easier to ignite.

At the same time, the utility model utilizes part of the waste heat of the flue gas at the tail of the boiler, which saves energy and improves the utilization efficiency of heat energy. And can effectively reduce the CO ₂ and NO _x in the boiler exhaust tail gas.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Detailed ways

As shown in FIG. 1 , a power plant pulverized coal boiler powder feeding device includes a powder bin 9 and a powder feeding airflow pipe 7 . The inlet end of the powder feeding flow pipe 7 communicates with the flue between the low-temperature superheater 2 and the economizer 3 of the pulverized coal boiler system 1 of the power station, and the outlet end communicates with the burner 12 of the pulverized coal boiler system 1 of the power station. The powder outlet of the powder bin 9 communicates with the powder feeding airflow pipe 7 through the powder feeder 10 . The powder feeding air flow pipe 7 is provided with a regulating valve 4 and a circulating fan 8, wherein the circulating fan 8 is arranged on the powder feeding air pipe 7 between the connection between the powder feeding air pipe and the powder feeder and the inlet end, and the regulating valve 4 is arranged on the On the powder feeding airflow pipe 7 between the circulating fan 8 and the inlet port. A section of the powder feeding airflow pipe 7 between the regulating valve 4 and the circulating fan 8 is connected with the adjacent furnace high-temperature flue gas pipeline 5 and the steam pipeline 6, and the adjacent furnace high-temperature flue gas pipeline 5 is connected with the pulverized coal boiler system of the adjacent furnace power station. The flue between the low-temperature superheater and the economizer is connected, and the steam pipeline 6 is connected with the medium-pressure steam pipeline of the utility station of the power plant. The powder feeding airflow pipe 7 between the circulating fan 8 and the outlet end is provided with an external heating device 11, which is a resistance heating device or an intermediate frequency heating device sleeved outside the pipeline.

During work, part of the high-temperature flue gas is extracted from the powder feeding airflow pipe 7 through the circulating fan 8 as the powder feeding flue gas, and then water vapor is mixed into the powder feeding flue gas through the steam pipeline 6 to form a powder feeding mixed gas, and the external heating device 11 is used to Heat the powder feeding mixture to keep it at a high temperature of 800-1000°C. The powder feeding machine 10 sends the pulverized coal in the powder bin 9 into the powder feeding airflow pipe 7, and uses the heated powder feeding mixed gas to send the pulverized coal with a concentration of 0.8-2kg/kg into the burner of the pulverized coal boiler of the power station , continue to use the external heating device 11 for heating during the powder feeding process, and keep the air temperature of the powder feeding mixed gas at 800-1000°C.

When the pulverized coal boiler system of the power station is started, the powder feeding flue gas is extracted from the running pulverized coal boiler system of the adjacent furnace power station through the high temperature flue gas pipeline 5 of the adjacent furnace; From its own power plant pulverized coal boiler system.

Claims (3)

1. A pulverized coal boiler powder feeding device of a power station, comprising a powder bin and a powder feeding airflow pipe, characterized in that: the smoke between the inlet end of the powder feeding airflow pipe and the low-temperature superheater and the economizer of the pulverized coal boiler system of the power station The outlet end is connected with the burner of the pulverized coal boiler system of the power station; the powder outlet of the powder bin is connected with the powder feeding air flow pipe through the powder feeding machine, and the powder feeding air flow pipe is equipped with a regulating valve and a circulation fan, and the circulation fan is set On the powder feeding air pipe between the connection between the powder feeding air pipe and the powder feeder and the inlet end, the regulating valve is set on the powder feeding air pipe between the circulating fan and the inlet end, and the section between the regulating valve and the circulating fan The high-temperature flue gas pipeline and steam pipeline of the adjacent furnace are connected to the powder feeding airflow pipe; an external heating device is arranged outside the powder feeding airflow pipe between the circulating fan and the outlet end. 2. A power plant pulverized coal boiler powder feeding device as claimed in claim 1, characterized in that: between the high-temperature flue gas pipeline of the adjacent furnace and the low-temperature superheater and economizer of other power plant pulverized coal boiler systems The flue is connected; the steam pipeline is connected with the medium-pressure steam pipeline of the utility station of the power plant. 3. A power plant pulverized coal boiler powder feeding device as claimed in claim 1, characterized in that: said external heating device is a resistance heating device or an intermediate frequency heating device sleeved outside the pipeline.

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