JP2543785Y2 - Circulating fluidized bed boiler - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating fluidized bed boiler capable of preventing explosion in a furnace when starting a cold can without any kind of fire and improving safety.

[0002]

2. Description of the Related Art In a circulating fluidized-bed boiler, when a cooler is started, combustion air is heated to about 900 ° C. by a duct burner to supply the combustion air to a furnace, and silica sand or the like stored in the furnace is heated. The bed material such as a desulfurizing agent such as an inert powder or limestone is fluidized by the combustion air to form a dense layer portion, and the bed material is heated to about 500 ° C. (coal spontaneous ignition temperature) or more, In this state, coal as fuel is put into the furnace, and the coal is spontaneously ignited by the heat of the bed material to start burning.

[0003]

[Problems to be Solved by the Invention] However, since coal combustion relies on spontaneous ignition from the start of combustion, volatile gas is generated before the coal starts burning, and this volatile gas is generated. Then, an explosion occurred in the furnace, damaging the equipment, adversely affecting the surroundings, and causing a safety problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circulating fluidized bed boiler capable of preventing explosion in a furnace due to volatile gas generated from input of coal to start of combustion and improving safety. It is assumed that.

[0005]

A furnace having a dense layer formed by a bed material on a lower side and a combustion gas outlet on an upper side; a combustion air supply pipe for supplying combustion air to the furnace; In a circulating fluidized bed boiler comprising a duct burner incorporated in a combustion air supply pipe capable of heating combustion air, and a cyclone communicating with a combustion gas discharge port of the furnace and returning separated particles to the furnace, the circulating fluidized bed boiler is formed in the furnace. Stone above the rich layer of the bed material and below the combustion gas outlet
Volatile gas generated from coal before it starts burning
The present invention relates to a circulating fluidized bed boiler provided with an on-bed burner for burning gas.

[0006]

The volatile gas generated during the period from the input of coal to the start of combustion can be burned by the on-layer burner, thereby preventing explosion in the furnace.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

First, a circulating fluidized bed boiler will be described.
In the figure, reference numeral 1 denotes a furnace, in which one end of a combustion air supply pipe 2 in which a duct burner (starting burner) 3 is incorporated is connected to the bottom of the furnace 1, and high-temperature combustion air 4 heated by the duct burner 3. Is supplied from the combustion air supply pipe 2 to the rich portion 5 of the furnace 1, and the rich portion 5 is provided with a fuel supply port 6 for supplying coal, limestone, and the like. A heat transfer tube 7 such as a steam generator or a superheater is provided in an upper portion of the furnace 1, and a combustion gas outlet 8 is provided in an upper portion of the furnace 1. Communicates with the upper part of cyclone 9,
The lower end of the cyclone 9 communicates with the rich layer 5 through a J valve 10 so that the furnace 1 → the combustion gas outlet 8
Floating particulates can be circulated in the route of → cyclone 9 → J valve 10 → furnace 1.

In the furnace 1 of the circulating fluidized-bed boiler described above, a position above the dense layer portion 5 where the input coal is spontaneously ignited by the heat of the fluidized medium as the bed material and burns, and below the combustion gas discharge port 8 ( In the passage in which the high-temperature combustion gas rises), an on-layer burner 11 for a fire is provided.

[0010] Heated by the duct burner 3 to about 900
° C is supplied from the combustion air supply pipe 2 into the furnace 1, and the supplied heated combustion air 4 heats the bed material in the rich layer portion 5 of the furnace 1. When the temperature reaches a temperature equal to or higher than the spontaneous ignition point of the coal (a temperature of about 500 ° C. or higher), coal or the like is charged into the dense layer portion 5. The injected coal is heated to the spontaneous ignition temperature by the heat of the bed material, and combustion starts.

Since coal is combusted by spontaneous combustion, a volatile gas 12 is generated before the coal starts burning, and this volatile gas 12 explodes in the furnace 1 or may be used in a subsequent process. There is a possibility of reaching the cyclone 9 and exploding in the cyclone 9. However, at the same time as the coal is injected into the rich layer 5, the burner 11 on the layer is ignited to burn the volatile gas 12 above the rich layer 5. As a result, the volatile gas 12 can be burned to prevent explosion, avoiding damage to equipment, and improving safety.

When coal combustion starts due to spontaneous ignition, the combustion operation of the on-bed burner 11 is stopped. At this time, the volatile gas 12 is not generated by the combustion of the coal.

It should be noted that the present invention is not limited to the embodiment shown and described. For example, it is optional to provide a plurality of on-layer burners, and various modifications may be made without departing from the gist of the present invention. Obviously you can get it.

[0014]

As described above, according to the circulating fluidized bed boiler of the present invention, since a large amount of volatile gas generated from the time of coal input to the start of combustion is burned, the furnace caused by the volatile gas is used. Various excellent effects such as prevention of occurrence of an internal explosion or the like, prevention of equipment damage and improvement of safety, and simplicity of the structure can be achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a circulating fluidized bed boiler of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace 2 Combustion air supply pipe 3 Duct burner 4 Combustion air 5 Rich layer part 6 Fuel supply port 8 Combustion gas discharge port 9 Cyclone 10 J valve 11 Layer burner 12 Volatile gas

Claims (1)

(57) [Scope of request for utility model registration] 1. A furnace having a dense layer formed by a bed material on a lower side and a combustion gas outlet on an upper side, a combustion air supply pipe for supplying combustion air to the furnace, and a combustion air supply In a circulating fluidized bed boiler equipped with a duct burner incorporated in a tube and capable of heating combustion air, and a cyclone communicating with a combustion gas outlet of the furnace and returning separated powder to the furnace,
Coal starts burning above the thick layer portion of the bed material formed in the furnace and below the combustion gas discharge port .
Before burning volatile gas generated from coal.
Circulating fluidized bed boiler, characterized in that a layer on the burner fit.