JPH0512601B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fluidized bed boiler device, and particularly to a fluidized bed boiler device suitable for controlling main steam temperature and reheat steam temperature during partial load operation.

[Background of the invention]

In a power generation boiler, when the turbine load decreases, (1) the drum pressure (temperature) decreases and the enthalpy at the superheater inlet increases; however, the rate of change in the enthalpy at the superheater outlet is small, so the enthalpy at the superheater decreases. Pickups will decrease. (2) As the feed water temperature decreases, the enthalpy of the feed water also decreases, so the enthalpy pickup of the economizer and evaporator increases. (3) As the steam pressure (temperature) at the reheater inlet decreases, the enthalpy at the reheater inlet decreases, so the enthalpy pickup of the reheater increases. (4) Regarding the flow rates of main steam and reheat steam, the rate of decrease in the flow rate of reheat steam flow rate is small but low compared to the main steam flow rate. For these reasons, the relationship between the heat absorption rate and the load in a power generation boiler is as shown in Figure 1.For superheated steam (SH), as the load decreases, the proportion of the total heat absorption decreases. , reheat steam (RH) shows a tendency to increase as the load decreases. In addition, W/W in the figure is a saturated water cooling wall, ECO
indicates an economizer.

In response to such heat absorption characteristics of superheated steam and reheated steam, fluidized bed boilers have conventionally adopted spray control or parallel control as steam temperature control.

FIGS. 2 and 3 schematically show a steam temperature control system for a conventional fluidized bed boiler. In Figure 2,
A first reheater 1, a first superheater 2, and a parallel damper 3 are installed in the convection section, and a second reheater 4 and a second
Superheater 5 is arranged in the same fluidized bed cell.
In this fluidized bed boiler, the steam temperature in the reheater is controlled by controlling a parallel damper 3, and the steam temperature in the superheater is controlled by a spray 6 installed between the convection section and the intrabed heat transfer section. It's summery.
Spray 7 is for emergencies and is not normally used. In such a fluidized bed boiler, part of the superheater and reheater must be installed in the convection section, so one of the advantages of a fluidized bed boiler is the use of interbed heat transfer tubes to reduce the heat transfer area. is damaged. Furthermore, the heat transfer area of the convection section is structurally located at the top of the boiler, whereas the intralayer heat transfer tube is located at the bottom of the boiler. For this reason, the piping of the communication pipe between the convection section and the intralayer heat transfer section becomes long.

In the fluidized bed boiler shown in Fig. 3, the first reheater 1
and the second reheater 4 are both arranged in the fluidized bed,
The first superheater 2 is arranged in the convection section, and the second superheater 5
is placed in a fluidized bed. In this fluidized bed boiler, steam temperature control in the reheater and steam temperature in the superheater are performed by sprays 8 and 9, respectively. When the load on the turbine increases, the first
The reheat steam decreases as shown in the figure. Therefore, in the fluidized bed boiler shown in FIG. 3, the amount of spray 9 must be increased as the load becomes higher.
This reduces plant efficiency.

[Purpose of the invention]

An object of the present invention is to provide a fluidized bed boiler device that can control main steam temperature and reheat steam temperature without compromising the compactness of the heat transfer area or reducing plant efficiency even when the boiler load fluctuates. Our goal is to provide the following.

[Summary of the invention]

The present invention provides a fluidized bed in which a reheater, a superheater, and an evaporator are all arranged in a fluidized bed, and at least a fluidized bed cell in which the reheater is arranged and a fluidized bed in which the superheater is arranged. In a fluidized bed boiler device in which cells are partitioned and fuel is input into each cell independently, the total amount of fuel input, which is the amount of fuel input into the entire fluidized bed boiler, is controlled to increase or decrease according to the boiler load. The fuel distribution ratio of the fuel input to each fluidized bed cell in which the heater, superheater, and evaporator are installed is as follows, with the total fuel input amount being 100:
It is characterized by being formed so as to be controlled according to the boiler load.

In this way, the present invention does not simply change the amount of fuel input into the fluidized bed cell for the reheater and the fluidized bed cell for the superheater, but rather changes the total fuel input amount, which is the amount of fuel input to the entire fluidized bed boiler. After controlling the increase or decrease according to the boiler load, the fuel distribution ratio of the fuel to be input to the fluidized bed cell for the reheater, the fluidized bed cell for the superheater, and the fluidized bed cell for the evaporator, respectively, is determined based on the total fuel input. The amount is set to 100, and control is performed according to the boiler load.

Although it varies depending on the specifications of the boiler turbine,
Conventionally, for example, as shown in Figure 1, the relationship between the heat absorption rate and the load in a heat generating boiler is that for superheated steam, the proportion of the total heat absorption decreases as the load decreases. , the proportion of reheated steam tends to increase as the load decreases. In this way, since both characteristics show different trends, the second
As shown in Fig. 3 and Fig. 3, it was difficult to maintain the specified main steam temperature and reheat steam temperature without spraying, etc., but with the above structure of the present invention, By simply controlling the increase/decrease of the total fuel input amount, and by setting the total fuel input amount as 100 and controlling the fuel mixture ratio to be input to each fluidized bed cell according to the boiler load, the specified amount can be achieved without installing a spray etc. Main steam temperature and reheat steam temperature can be maintained.

[Embodiments of the invention]

FIG. 4 shows an embodiment of the present invention, in which a reheater 11, a superheater 12, and an evaporator 13 are arranged in separate fluidized bed cells A, B, and C, respectively, partitioned by peripheral walls. It is set up. Furthermore, an economizer 14 is provided in the convection section.

In this fluidized bed boiler apparatus, as shown in FIG. 5, the fluidized bed cell B in which the superheater 12 is installed can secure the required amount of heat absorption by the superheater 12 due to load fluctuations and changes in the area of the fluidized part of the bed. (When operating by changing the bed area of the fluidized part with respect to the structural bed cross-sectional area) 63%
Adjust the fuel input ratio from 50% to 50%.

On the other hand, in the fluidized bed cell A equipped with the reheater 11, the rate is 13% depending on the load fluctuation and the area change of the fluidized part.
Adjust the fuel input ratio to about 17%.

As a result, by adjusting the fuel input ratio to fluidized bed cells A and B, the main steam and reheated steam can be maintained at the specified steam temperature only on the intrabed heat transfer surface, making it necessary to control the steam temperature by spraying. I don't.

However, since the amount of fuel input into the fluidized bed boiler is determined according to the load, the amount of fuel input into the entire boiler can be adjusted by the amount of fuel input into the fluidized bed cell C in which the evaporator 13 is installed. conduct. In other words, the amount of fuel input to the fluidized bed cell C in which the evaporator 13 is installed is the amount obtained by subtracting the amount of fuel input to the fluidized bed cell A and the fluidized bed cell B from the amount of fuel input to the entire boiler when the load is constant. amount. Therefore, as shown in Figure 5, the fuel input ratio to fluidized bed cell C is 35.5.
Adjust from % to 25%. By adjusting the distribution of fuel input to each bed (fluidized bed cell) in this way, the amount of heat absorbed by the reheater 11, superheater 12, and evaporator 13 can be controlled independently by the amount of fuel for each bed. The specified steam temperature and evaporation amount can be maintained.

FIG. 6 shows another embodiment of the present invention, in which the evaporator 21 and the second superheater 22 are arranged in the same fluidized bed (this part is called fluidized bed cell D). The heater 23 is disposed within the fluidized bed in the fluidized bed cell E divided by the fluidized bed cell D and the peripheral wall, and a spray 24 is provided between the convection section and the intrabed heat transfer section of the superheater. There is. Further, a first superheater 25 and an economizer 26 are arranged in the convection section. That is, this embodiment differs from the embodiment shown in FIG. 4 in that it does not have a bed in which only an evaporator is disposed.

In such a fluidized bed boiler device, the reheat steam temperature (ROT) is controlled by the amount of fuel input into the fluidized bed cell E. On the other hand, each fluidized bed cell (bed)
If the ratio of fuel input to the bed changes, it is not possible to control the fluctuation of the amount of evaporation in the water cooling wall that forms the peripheral wall of the bed. Therefore, in this example, the fluidized bed cell D
The fuel necessary to obtain a specified amount of evaporation is injected into the main steam temperature, and the main steam temperature can be controlled by the amount of spray in the sprayer 24. In this example, a spray control method is adopted, but even if the operation shifts to high load, the reheating steam temperature itself remains unchanged in the fluidized bed cell E.
Since the amount of fuel input to the plant is controlled, there is very little decrease in plant efficiency.

In the present invention, when the evaporator is arranged in a separate fluidized bed cell separated from a fluidized bed cell in which a superheater and a reheater are respectively arranged as shown in FIG. 4, a superheater is arranged. The evaporator may be provided in a fluidized bed cell provided with a reheater or a fluidized bed cell provided with a reheater. In addition, in the case where the evaporator is installed in a separate fluidized bed cell separated from a fluidized bed cell each equipped with a superheater and a reheater, as shown in FIG. A reheater may be co-located in the cell, or a superheater may be co-located in a fluidized bed cell provided with a reheater. Even in these cases, the prescribed main steam temperature and reheat steam temperature can be maintained by adjusting the fuel input ratio to each fluidized bed cell according to the operating load.

〔Effect of the invention〕

According to the present invention, the total fuel input amount is controlled to increase or decrease according to the boiler load, and the fuel distribution ratio to be input to each fluidized bed cell is controlled according to the boiler load, with this total fuel input amount being 100. It is possible to maintain the specified main steam temperature and reheat steam temperature without installing a spray or the like.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the relationship between the heat absorption rate of each part of the boiler and the load in a heat generating boiler, Figures 2 and 3 are schematic configuration diagrams of a conventional fluidized bed boiler, and Figure 4
The figure is a schematic configuration diagram showing one embodiment of the present invention.
The figure is an explanatory diagram of the boiler load characteristics of the fluidized bed boiler apparatus of FIG. 4, and FIG. 6 is a schematic configuration diagram showing another embodiment of the present invention. 1, 4, 11, 23... Reheater, 2, 5, 1
2, 22, 25... Superheater, 3... Parallel damper, 6, 7, 8, 9, 24... Spray, 13, 2
1... Evaporator, 10, 14, 26... Economizer.

Claims (1)

[Claims] 1. A reheater, a superheater, and an evaporator are all disposed within a fluidized bed, and at least a fluidized bed cell in which the reheater is disposed and the superheater are disposed. In a fluidized bed boiler device in which fuel is input independently into fluidized bed cells separated from each other, the total amount of fuel input, which is the amount of fuel input into the entire fluidized bed boiler, is controlled to increase or decrease according to the boiler load, Further, the fuel distribution ratio of the fuel input to each fluidized bed cell in which the reheater, the superheater, and the evaporator are arranged is controlled according to the boiler load, with the total fuel input amount being 100. A fluidized bed boiler device characterized by: 2. The fluidized bed according to claim 1, wherein the evaporator is disposed in a separate fluidized bed cell separated from a fluidized bed cell in which the superheater and reheater are respectively disposed. Layer boiler equipment. 3. The fluidized bed boiler device according to claim 1, wherein the evaporator is disposed within a fluidized bed cell in which a superheater is disposed.