JPS6057103A - Method of feeding pulverized fuel to multistage type fluidized-bed boiler - Google Patents

Abstract

PURPOSE:To perform rapid and smooth feed control of pulverized fuel, by a method wherein a plurality of combustion zones are independently formed, an independent pulverized fuel feed equipment is located in juxtaposition therewith, and an amount of the pulverized fuel supplied is controlled through detection of a required combustion amount at each combustion zone. CONSTITUTION:3 pulverized fuel outlet ports 1, 2, and 3 are formed in the base of a pressurizing container Ai, exhaust gas, fed in the direction of an arrow mark along a line 28, is branched into 3 gas flows flowing through a valve 18, and the branched gases are respectively forcibly fed to the outlet ports 1, 2, and 3. Through lines 7, 8, and 9, feed gas for blowing in pulverized fuel through inlet ports 25, 26, and 27 is fed, the feed gas flows to mixing tees 10 through flow meters 15, 16, and 17 and valves 22, 23, and 24, and the feed gas joins the discharged pulverized fuel. The fuel is conveyed by means of a gas flow through feed lines 7', 8', and 9', and is fed to the inlet ports 25, 26, and 27. According to an instruction from a differential pressure control loop 14, the opening of the valve 18 is regulated to regulate a feed amount.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the combustion of not only each unit combustion zone but also the entire boiler by controlling the supply of granular fuel to each combustion zone that constitutes a multi-stage fluidized bed boiler. It is related to.

The fluidized bed combustion method was developed as a relatively low-temperature combustion method for granular coal (usually less than 10 mm in diameter), and is clean due to in-furnace desulfurization and in-furnace denitrification, has a wide usable range of fuel, and requires a small installation area. There are high expectations for the fact that coarse granulated coal can be used. Furthermore, since it is easy to increase the capacity through a rational module configuration, multi-stage fluidized bed boilers for power plants, for example, are being designed.

In such a multi-stage fluidized bed boiler, multiple combustion zones are arranged independently, but if the granular fuel cannot be distributed correctly and evenly to each combustion zone, each combustion Combustion conditions in the zone become non-uniform, reducing the accuracy of combustion management, and the advantages of the fluidized bed combustion method described above may be hindered. Furthermore, if it becomes necessary to adjust the distributed supply amount of granular fuel in response to fluctuations in the amount of steam required on the boiler side, it goes without saying that it is necessary to ensure that the correct response is taken.

The present invention was made in consideration of such a situation, and the object thereof is to establish a technology for adjusting and supplying granular fuel to a multi-stage fluidized bed boiler. That is, the granular fuel supply method according to the present invention is to provide a multi-stage fluidized bed boiler with a plurality of combustion zones each independently, and to supply granular fuel corresponding to and independent of each combustion zone. The main idea is to install a supply facility, detect the required combustion amount for each combustion zone, and control the amount of granular fuel supplied to each zone.

FIG. 1 is an explanatory diagram for showing the implementation background of the method of the present invention, and shows A, to A,. Each indicates a pressurized holding container for granular fuel that holds granular fuel under pressure, but when expressed representatively, it is simply referred to as pressurized vessel At, and when expressed as a whole, it is referred to as pressurized vessel group A. To tell. On the other hand, B.

-B1° are unit fluidized bed combustion boilers, which are hereinafter referred to as combustion zone Bi when expressed representatively, and referred to as multistage fluidized bed boiler B or simply boiler B when expressed as a whole. The pressurized container Ai and the combustion zone Bi are each installed independently, and in the figure, each
There are 0 units each, but their number is at least 1:1.
The present invention can be satisfied within the corresponding limit, and if necessary, a larger number of pressurized containers AiO can be installed as a backup. For ease of understanding, the pressurized container Ai and the combustion zone Bi are connected to each other by powder and granular fuel supply lines C3 to C8° (hereinafter referred to as supply line Ct when expressed representatively). do. Therefore, when performing combustion control in the combustion zone Bi, it is only necessary to focus on the corresponding pressurized vessel AI and supply line C1 and control the start or stop, increase or decrease of fuel supply. , the speed and precision of control will be extremely high. The control is started when the required combustion amount for the boiler B as a whole is changed, and an example of control using the equipment shown in Fig. 1 is as follows.

(1) When the required combustion amount of boiler B is 10096: 1
All 0 pressurized containers At are in operation, and each is 100
The vehicle shall be operated at

(2) At 50 cm: All 5 pressurized vessels Ai are operated at 100% operation, and the remaining 5 pressurized vessels Ai are stopped and the corresponding combustion zone B is started.
Stop burning i.

(3) For the 45th section: In the operation of (2) above, four of the five operating units are operated at 100 degrees, and one unit is operated at 50q6.

(4) When the same number of units is 5: Following (3) above, only one unit is operated and the one unit currently in operation is operated at 50%.

By controlling as described above, it is possible to quickly and accurately respond to large fluctuations in the amount of combustion required in boiler B. By the way, from the pressurized container Ai to the combustion zone B1
When adjusting the amount of powdered fuel supplied to
It is necessary to control according to the linear functional relationship shown in FIG. In other words, the vertical axis in FIG.
The difference (Pa-
Pb-ΔP)J is shown, and the horizontal axis shows the powder fuel supply amount (R) at that time. Since there is a linear proportional relationship between the two as shown in the figure, the supply amount can be changed from R2 to Rl, for example.
It can be seen that when it is desired to reduce the pressure by i, it is sufficient to reduce the pressure difference from ΔP to ΔP. Of course, if the pressure pb in the combustion zone Bi fluctuates too much, ΔP
Alternatively, it is also possible to control by considering only the pressure Pa in the pressurized vessel Ai, and this is recommended as a simple method, especially in the case of a multi-stage fluidized bed boiler.

In each of the above explanations, the supply line Ci connecting the pressurized container AI and the combustion zone Bi is explained as one for convenience, and although it is theoretically possible, in practical equipment, the supply line C
Since each i may be composed of several tens of wires, this case will be explained below, but for ease of understanding, the case where the number i is composed of three wires is shown in the figure.

That is, FIG. 2 shows an example in which a specific pressurized container Ai and a specific combustion zone Bi are connected by three supply lines Ci, and three granular fuel outlets are provided at the bottom of the pressurized container At. 1,
2.3 is formed, and the discharged gas is purified and supplied to the line 28 in the direction of the arrow [Generally, an inert gas such as nitrogen is used, but the granular fuel in this example has a relatively large diameter. (Normally less than 10mmφ, sometimes up to 20mmφ)
Since there is a high risk of dust explosion, air can be used.] After passing through the pulp 18, it is branched into three branches and is press-fitted into each outlet 1, 2.3. Outlet 1. ... is equipped with a baffle or the like as necessary, and the granular fuel in the pressurized container At is smoothly dispensed while passing around the baffle along with the discharging gas, and is discharged from the dispensing line 4 + 5 + 6. The airflow is conveyed to the mixing tee 10.11°12 through the . Note that 19,20°21 indicates pulp.

On the other hand, granular fuel is supplied from line 7.8.9 to injection port 25.
26.27 Feed gas is supplied for blowing into the pulp (air is used for the same reasons as above, and to avoid interfering with combustion in the combustion zone Bi), and the flow meter 15.16.17 and the pulp 22, 23.

Mixing tee 10 via 24. ..., which is combined with the discharged granular fuel and further conveyed by airflow via the feed line 7'l8'+9', to the inlet port 25. ...is supplied to...

In the example shown, outlet 1. ... number and inlet 25. ...
The numbers of the feed lines 7', . . .
If you want to branch out in the middle, the above correspondence is set to 1=2
It is also possible to change the ratio to 1:3, etc. However, the inlet 25 due to such a branch. When grouping...
It goes without saying that care must be taken to ensure that the pressure drop difference in the feed lines 7', . . . after the branching is as small as possible to belong to the same group.

In order to control the above-mentioned ΔP in such a device, it is necessary to measure the pressure inside the pressurized container Ai with the pressure gauge 13 and separately pressurize air into the container A1 (υ), or to perform a separate air vent. Although it may be adopted, the differential pressure control loop 14
It is also reasonable to have a means of adjusting the opening degree of the pulp 18 according to the instructions. This is the outlet 1. This is because the pressure inside the pressurized container At can be varied depending on the amount of gas discharged from the pressurized gas, and the supply amount can be adjusted by operating the pulp 18.

Since the present invention is constructed as described above, it has become possible to quickly, reliably and smoothly control the supply of granular fuel to a multi-stage fluidized bed boiler.

[Brief explanation of the drawing]

Figure 1 is an overall conceptual diagram of the granular fuel supply equipment for a multi-stage fluidized bed boiler, Figure 2 is an explanatory diagram showing the supply status of granular fuel to a unit combustion zone, and Figure 3 is a diagram showing differential pressure and granular fuel. 2 is a graph showing the relationship between body fuel supply amount. A: Powder fuel pressurized holding container group B: Fluidized bed combustion boiler (combustion zone) C: Powder fuel supply line Applicant Kobe Steel, Ltd.

Claims (1)

[Scope of Claims] (]) Providing independent granular fuel supply equipment corresponding to each combustion zone of a multi-stage fluidized bed boiler in which a plurality of combustion zones are arranged independently, respectively; A method for supplying granular fuel to a multistage fluidized bed boiler, characterized by detecting the required combustion amount for each combustion zone and controlling the amount of granular fuel supplied to each zone. (2) Each granular fuel supply equipment consists of a pressurized granular fuel holding container that holds the granular fuel under pressure and has a granular fuel outlet at the bottom, and a granular fuel pressurized holding container that holds the granular fuel under pressure and discharges the granular fuel to the outlet. A granular fuel delivery line that presses in gas and delivers granular fuel from the outlet, and a granular fuel supply line that merges with the delivery line and delivers granular fuel to the combustion zone. 2. The granular fuel supply method according to claim 1, wherein the granular fuel supply is controlled by adjusting the pressure within the granular fuel pressurized holding container. (3) Each granular fuel supply equipment consists of a pressurized granular fuel holding container that holds the granular fuel under pressure and has a plurality of granular fuel outlets at the bottom, and A plurality of granular fuel discharging lines which pressurize dispensing gas into each granular fuel outlet and discharge the granular fuel from the outlet; and a plurality of granular fuel discharging lines that merge into each dispensing line and combust the granular fuel as described above. It is composed of a plurality of granular fuel supply lines that feed the granular fuel to the zone, and the pressure inside the granular fuel pressurized holding container is adjusted, or the granular fuel dispensing line and the granular fuel supply line Claim 1, wherein the supply of granular fuel is controlled by controlling the flow rate of all or part of each supply line consisting of the above, or by stopping or restarting supply of any one of the supply lines. The powder fuel supply method described.