JPH053841Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> This invention relates to a fluidized bed boiler, and particularly to a fluidized bed boiler device that can effectively prevent burnout of interbed heat exchanger tubes even when the plant is shut down.

<Prior art and its problems> In a fluidized bed boiler, the heat transfer coefficient in the fluidized bed is several times higher than that in the empty column, so heat transfer tubes are placed in the bed to connect the evaporator, superheater, It is used as a reheater, etc. Figure 2 shows an example of a conventional fluidized bed boiler.
It descends and enters the evaporator 6 placed in the fluidized bed 5 in the boiler body 4 by the circulation pump 3 to recover the heat in the bed, and then returns to the boiler drum 1 via the riser pipe 7. The steam generated by the circulating flow of the canned water flows through a pipe 8' into a superheater 8, which is also an intralayer heat transfer tube, and is turned into superheated steam, which is then supplied to a high-pressure turbine 9. The steam leaving the high-pressure turbine 9 flows into a reheater 10, which is another intralayer heat transfer tube, and is resuperheated, and then supplied to a low-pressure turbine 11. Steam exiting the low-pressure turbine 11 is cooled to water in a condenser 12, and is returned to the drum 1 via a deaerator 13 and a pump 14.

In the above-mentioned apparatus, if fluid flow inside the boiler becomes impossible due to a power outage in the plant or a failure of the pump, there is a risk that the intrabed heat exchanger tubes will be burned out by the residual heat of the fluidized bed 5. As for the evaporator 6, it is possible to cool the pipe body by the flow of the internal fluid by performing natural circulation, and the inventors and others have bypassed the pump 3 which acts as resistance during this natural circulation to cool the internal fluid. A bypass pipe 15 is proposed that allows the fluid to flow.

However, in the case of superheaters and reheaters, such flow cannot be expected at all because the internal fluid is steam.

<Means for solving the problem> This idea was constructed in order to solve the above-mentioned problems, and in order to prevent burnout of the superheater and reheater, which are intralayer heat transfer tubes, the steam, which is the internal fluid, is The structure is such that the steam is allowed to flow and the tube body is cooled by this steam.

<Summary of the Means> In short, this invention consists of a boiler drum, a superheater in a fluidized bed, a high-pressure turbine with a steam inlet valve, a reheater, and a low-pressure turbine connected in series through a pipe.
A discharge pipe with a steam release valve 20 is provided which branches from a pipe connecting the reheater and the low-pressure turbine and releases steam to the outside of the system, and the steam is released by a signal from a pressure sensor installed in the branch pipe. A pipe line that separates a high-pressure turbine from a steam flow path in a fluidized bed boiler that opens a valve 20 and adjusts the amount of steam released to prevent burnout of the superheater tube and the reheater tube in the event of an in-house power outage or turbine failure. A valve 21 connecting the high pressure turbine inlet line 16 with a valve 27 and the reheater inlet line 17
This is a burnout-prevention type fluidized bed boiler characterized by having a bypass pipe line 18.

<Example> Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 1, a high-pressure turbine inlet pipe 16 with an inlet valve 27 that connects the superheater 8 and the high-pressure turbine 9, and a reheater inlet pipe 17 that connects the high-pressure turbine 9 and the reheater 10, It is connected by a bypass line 18 with a valve 21 so as to bypass the high pressure turbine 9. On the other hand, a steam release valve 20 is attached to a low-pressure steam line 19 that connects the outlet of the reheater 10 and the low-pressure turbine 11 to release internal steam to the outside of the system (for example, into the atmosphere). Since this valve allows steam to flow while suppressing the residual pressure in the boiler as much as possible, as will be described later, it is desirable that it be able to be finely adjusted and be small.

In the above configuration, if the flow of steam in the intralayer heat transfer tubes stops due to a power outage or the like, the following operation is performed. That is, the inlet valve 27 of the high-pressure turbine 9 is closed and the valve 21 of the bypass line 18 is opened so that steam bypasses the high-pressure turbine and flows into the reheater 10, and the steam release valve 20 is opened to allow steam to flow into the reheater 10. is released outside the system. As a result, superheater 8 and reheater 1
0, steam flows, and this steam cools the tube body, thereby preventing burnout of the superheater tube and reheater tube due to residual heat of the fluidized bed 5. In this case, since the steam is discharged using the residual pressure of the boiler, the flow of steam in the tube must be kept to a minimum and necessary to prevent burnout of the superheater and reheater. Therefore,
It is preferable that the pressure inside the drum is detected by the pressure detector 22, and the opening degree of the steam release valve 20 is adjusted based on this.

In this case, if the evaporator 6 is arranged as an intrabed heat transfer tube, the canned water is circulated and flowed to prevent burnout of the evaporator 6 as described above, so that the heat in the fluidized bed is supplied to the drum 1. , this will serve to suppress the drop in boiler residual pressure.

<Effects> By implementing this idea, even if there is a risk of burnout of the superheater, reheater, etc. due to residual heat in the fluidized bed due to an in-house power outage, etc., the superheater, reheater, etc. can be removed by simply controlling the steam release valve 20. The steam flow rate in the heater can be controlled at the same time, and the residual pressure of the boiler can be used to effectively prevent burnout of these devices.

[Brief explanation of drawings]

Figure 1 is a drawing showing an embodiment of this invention;
The figure is a piping system diagram according to the prior art. 1... Boiler drum, 4... Boiler body, 5...
... Fluidized bed, 8 ... Superheater, 10 ... Reheater, 20
...Steam release valve, 27...Inlet valve.

Claims (1)

[Scope of utility model registration request] A boiler drum, a superheater in a fluidized bed, a high-pressure turbine with a steam inlet valve, a reheater, and a low-pressure turbine are connected in series by a pipe line, and a pipe branching from the pipe line connecting the reheater and the low-pressure turbine is provided. A discharge pipe with a steam release valve 20 for releasing steam outside the system is provided, and the steam release valve 20 is opened in response to a signal from a pressure detector installed in the branch pipe to adjust the amount of steam released, thereby preventing power outage within the station. In a fluidized bed boiler that prevents burnout of the superheater tube and the reheater tube in the event of turbine failure, a valve 27 separates the high pressure turbine from the steam flow path.
A burnout-preventing fluidized bed boiler characterized in that a bypass pipe 18 with a valve 21 connects a high-pressure turbine inlet pipe 16 and a reheater inlet pipe 17.