JP2002267154A - Boiler device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unburnt matters in ash and achieve a highly efficient operation by more raising the temperature of combustion air of a boiler. SOLUTION: A boiler device having a heater 6 relatively little in temperature change due to heat absorption is provided with an air duct evaporator 9 connected in parallel with the heater 6. The temperature of the combustion air supplied from an air preheater 2 is raised through the air duct evaporator 9 to supply the combustion air to a boiler wind box 3. The air duct evaporator 9 has its inlet/outlet connected to the heater 6 by communicating pipes 8. Flow rate is adjusted by valves 10 disposed in the communicating pipes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler, and more particularly to a boiler suitable for reducing unburned ash in coal-fired boilers.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional boiler apparatus. The air sent from the pushing fan 1 is approximately 300
It is heated to about ° C and sent to the wind box 3.
The combustion air sent from the wind box 3 is supplied to the furnace 4
Combustion with fuel at, superheater 5, evaporator 6, economizer 7
And heat is recovered by the air preheater 2 and sent to the chimney.

[0003] The conventional boiler apparatus has a system for directly supplying combustion air heated by the air preheater 2 to the wind box 3.

[0004]

In the above prior art, since only the air preheater 2 is heated, no consideration has been given to a rise in the temperature of combustion air that is effective in reducing unburned ash in ash.

An object of the present invention is to further reduce the unburned ash content by further increasing the temperature of the combustion air.
The purpose is to enable more efficient operation.

[0006]

In order to solve the above problems, the present invention mainly employs the following configuration. A boiler device having a heater having a relatively small temperature change due to heat absorption, comprising a wind path evaporator connected in parallel with the heater, wherein the combustion air sent from an air preheater is supplied to the air path evaporator. A boiler device that raises the temperature through the boiler and feeds it to the boiler wind box.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A boiler device according to an embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing a schematic flue duct system and a fluid path in a boiler apparatus according to an embodiment of the present invention, wherein 1 is a push-in fan, 2 is an air preheater, 3 is a wind box, 4 is a furnace and Cage, 5 is a superheater, 6 is an evaporator, 7 is a economizer, 8 is a connecting pipe, 9 is an airway evaporator, 10 is a valve, and 11 is a steam separator.

In FIG. 1A, the combustion air sent from the pushing fan 1 is heated to about 300 ° C. by an air preheater 2 and further heated by an airway evaporator 9. The high-temperature combustion air is burned together with the fuel in the furnace 4,
After passing through the superheater 5, the evaporator 6, and the economizer 7, heat is recovered by the air preheater 2 and sent to the chimney. The above is a series of flows of the air from the pushing fan.

FIG. 1 (2) shows the flow path of the boiler water. The connection relationship between the evaporator 6 and the wind path evaporator 9 is as shown. The airway evaporator 9 is connected to the entrance and exit of the evaporator 6 by a communication pipe 8, and the flow rate is adjusted by a valve 10. The wind path evaporator 9 uses saturated steam (about 400 to 420 ° C.) taken out from the inlet of the evaporator 6 as a heat source. The fluid that has passed through the airway evaporator 9 is returned to the brackish water separator inlet 11.

As described above, the air sent from the pushing fan 1 is heated to about 300 ° C. by the air preheater 2 and then taken out from the inlet of the evaporator 6 before being put into the wind box 3. The air is further heated by an airway evaporator 9 using saturated steam (about 400 to 420 ° C.) as a heat source. At this time, the combustion air heated to about 300 ° C. by the air preheater 2 is further heated by the airway evaporator 9 to 20 to 30 ° C.

[0011] The higher the temperature of the combustion air charged to the boiler, the lower the unburned ash content in the ash is,
This enables highly efficient operation. As shown in FIG. 4, when the temperature of the combustion air is increased by 20 ° C., about 10 to 15
%, The unburned matter in the ash is reduced, and the boiler can be operated with high efficiency.

Here, the temperature of the combustion air can be increased by increasing the temperature of the gas at the boiler outlet by adjusting the boiler transmission surface, but in this case, the boiler efficiency is reduced. But,
In the present invention, since the air on the outlet side of the air preheater is heated, the efficiency can be improved without a decrease in the boiler efficiency due to an increase in the gas temperature.

FIG. 3 shows a P-I diagram of a certain plant. As shown in the drawing, the temperature rise in the evaporator is as small as 5 to 7 ° C. due to the characteristics of the pressure and temperature range. The temperature difference with the fluid that has passed through the evaporator is also small. Here, the fluid (water / steam) passing through the evaporator 6 has a characteristic that the temperature change is small even if the enthalpy rises due to heat absorption. It can be said that there is little temperature difference with the fluid returning to boiler and there is almost no influence on the boiler characteristics.

[0014]

According to the present invention, it is possible to reduce the unburned portion in the ash and to heat the air at the outlet side of the air preheater, thereby improving the efficiency without lowering the boiler efficiency due to a rise in gas temperature. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic flue duct system and a fluid path in a boiler device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic flue duct system and a fluid path in the prior art.

FIG. 3 is a diagram showing an example of a PI diagram of a plant.

FIG. 4 is a diagram showing a relationship between air temperature and unburned ash content.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Push fan 2 Air preheater 3 Wind box 4 Furnace / cage 5 Superheater 6 Evaporator 7 Energy saving device 8 Communication tube 9 Airway evaporator 10 Valve 11 Steam separator

Claims (2)

[Claims] 1. A boiler device having a heater having a relatively small temperature change due to heat absorption, comprising a wind path evaporator connected in parallel with the heater, wherein a combustion air sent from an air preheater is supplied. A boiler device, wherein the temperature is increased through the wind path evaporator and is supplied to a boiler wind box. 2. The boiler device according to claim 1, wherein the air path evaporator is connected to the heater and its inlet and outlet by a connecting pipe, and the flow rate is adjusted by a valve installed in the connecting pipe. Boiler equipment characterized.