JPH0311521Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fluidized bed boiler, and particularly to a fluidized bed boiler having an evaporator tube, a reheater tube, and a superheater tube each provided in the fluidized bed. , relates to a fluidized bed boiler suitable for securing cooling steam for reheater tubes and superheater tubes at the initial stage of startup.

[Background of the idea]

Conventionally, in a fluidized bed boiler, an evaporator tube 6, a reheater tube 5, and a superheater tube 4 are each provided within the fluidized bed as shown in Figure 1, so the thermal conductivity is high and the heat transfer area can be made compact. There are advantages that can be achieved. However, the combustion temperature (layer temperature) of the fluidized bed is 800
~900°C, so when the fluid boiler is started, cooling water or steam flows into the superheater tubes 4 and reheater tubes 5 until they reach steady operation. If the tube is empty, the tube temperature will rise and burnout may occur.

For this reason, in the fluidized bed boiler shown in FIG. 1, the following operating method is used to prevent burnout of the superheater tube 4 and reheater tube 5 during startup. In other words, the first operating method is to
Hot air 9 of around 800℃ is sent into each fluidized bed, and steam is gradually generated in the evaporator tube 6 while maintaining the bed temperature of each fluidized bed at 500 to 600℃, which is below the allowable metal temperature of the inner tube material. and superheater tube 4 and reheater tube 5
In this method, after a sufficient steam flow rate for cooling is secured within the reactor, fuel is injected into each fluidized bed to raise the bed temperature to 800 to 900°C, and steady operation begins. The second operating method is to attach the burner 1 (hereinafter referred to as the above-bed burner) to the peripheral wall above the bed of the fluidized bed, as shown in Fig. 1.
Before starting each fluidized bed, the water-cooled wall 3 is heated by the over-bed burner 1, and the steam generated here is vented to the superheater tube 4 and the reheater tube 5, and then the starting of each fluidized bed is started. It's a method.

In the first operation method, steam is generated at a relatively low layer temperature of 500 to 600°C, so it takes a very long time to secure cooling steam in the superheater tube 4 and reheater tube 5. , it takes time to reach normal operation by adding fuel to this part. In other words, the starting loss increases.

In the second operating method, the start-up time is shorter than in the first operating method, but in order to efficiently heat the water-cooled wall 3 and generate cooling steam, a plurality of bed burners are required. In addition to the equipment costs for the main body, the initial cost increases due to the reinforcement of the steel frame and other supports due to the increased weight of the boiler main body due to the installation of layered burners.

[Purpose of invention]

An object of the present invention is to provide a fluidized bed boiler that can be started up in a short time without requiring a bed burner and without burning out tubes in the fluidized bed.

(Summary of the invention) In this invention, a fluidized bed cell with an evaporator tube is separated from a cell with a reheater tube and a superheater tube, and the fluidized bed cell with an evaporator tube is operated independently at the initial stage of startup. However, the steam generated here is used as cooling steam for the reheater tube and superheater tube.

[Example of idea]

2 and 3 respectively show an embodiment of the present invention, in FIG. 2, a fluidized bed 11 with an evaporator tube 10, a fluidized bed 14 with a superheater tube 12 and a reheater tube 13, and a peripheral wall 15. It is divided through. Further, the evaporator 10, superheater tube 12, and reheater tube 13 are each connected to an air/water drum (not shown). Furthermore, fluidized bed 11 and fluidized bed 1
4 is the same as the conventional example in that hot air 9 from the hot air stove 2 is introduced into each of them.
This differs from the conventional example in that the layered burner 1 is not provided.

When starting up, start the blower and water pump,
Purging of the exhaust gas pipe before startup is the same as before. After these operations, both the fluidized bed 11 and the fluidized bed 14 are heated by the hot air 9 from the hot air stove 2.
A layer temperature of 500-600℃ is reached. Next, when heating material (coal powder) is introduced only into the fluidized bed 11, the coal starts to heat up and the bed temperature of the fluidized bed 11 rises to 800 to 900°C. As the bed temperature of the fluidized bed 11 increases, the evaporation tube 10
The steam generated therein is vented to the superheater tube 12 and the reheater tube 13 via an air/water drum (not shown). The amount of fuel input to the fluidized bed 14 is gradually increased in accordance with the increase in the amount of vented steam in the superheater tube 12 and the reheater tube 13. When the amount of aeration steam in the superheater tube 12 and the reheater tube 13 reaches 25% MCR, steady operation of the fluidized bed 14 is started, and the bed temperature here is maintained at 800 to 900°C. During operation of the fluidized bed boiler, combustion gas flows in the direction shown by the arrow in the figure, passes through the economizer 7, and is discharged to the outside of the furnace.

Note that the above-mentioned starting operation can be automatically performed by a starting control means (not shown). That is, after the startup control means supplies fuel to the fluidized bed 11 and starts it, it detects the amount of ventilation steam in the superheater tube 12 and the reheater tube 13, and if the value is, for example, 25
When %MCR is reached, the fuel supply means for the fluidized bed 14 is controlled to increase the amount of fuel input to an amount suitable for steady operation. Such a starting control means itself can be easily realized by combining well-known techniques in accordance with the above-described starting operation procedure that is a feature of the present invention.

In FIG. 3, in place of the hot air furnace and hot air supply line in FIG. 2, in-bed burners 16 and 17 are provided in the fluidized bed 11 and fluidized bed 14, respectively,
8 and reheater tube 19 are arranged in upper and lower stages of the same fluidized bed.

In the fluidized bed boiler shown in FIG. 3, at startup, the fluidized bed 11 and the fluidized bed 14 are first heated to a bed temperature of 500 to 600°C by the burners 16 and 17 in the bed, and then the fluidized bed 11 is heated with fuel. (coal powder) is introduced. The subsequent operation method is the same as the method explained based on FIG. 2.

This embodiment also has effects similar to those of the above embodiment.

[Effect of idea]

As described above, according to the present invention, there is no need to provide an overbed burner, and the first fluidized bed cell with an evaporator can be maintained at a bed temperature of 800 to 900°C even in the initial stage of startup, so it can be reheated in a short time. The necessary amount of steam can be secured in the container tube and the heater tube, and the startup time can be shortened without burning out the tubes.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional fluidized bed boiler.
FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 3 is a schematic diagram showing another embodiment of the present invention. 1... Upper layer burner, 4, 12, 18... Superheater tube, 5, 13, 19... Reheater tube, 6, 10...
Evaporation tube, 7... Economizer, 16, 17... In-bed burner.

Claims (1)

[Claims for Utility Model Registration] (1) A first fluidized bed cell having an evaporator tube, a second fluidized bed cell separated from this cell and having a reheater tube and a superheater tube, and a first fluidized bed cell having a reheater tube and a superheater tube. a line for introducing steam generated in the evaporator tube into the reheater tube and the superheater tube when starting the fluidized bed cell, and a start control means for controlling start of the first and second fluidized bed cells. , after starting the first fluidized bed cell, the startup control means detects an amount of aeration vapor introduced from the evaporation tube to the reheater tube and the superheater tube via the line, A fluidized bed boiler characterized in that steady operation of the second fluidized bed cell is started after detecting that the amount of aeration steam has reached a predetermined value. (2) The fluidized bed boiler according to claim 1, wherein the first fluidized bed cell and the second fluidized bed cell are separated by a peripheral wall. (3) The first fluidized bed cell and the second fluidized bed cell are provided below and communicate with each other via a wind box divided into two and a dispersion plate. A fluidized bed boiler according to claim 1 of the utility model registration claim.