JPH036404B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fluidized bed combustion method and apparatus,
In particular, the present invention relates to a method and apparatus for effectively carrying out load control operation of a fluidized bed boiler.

<Prior art and its problems> Fluidized bed equipment, which fluidizes a fluidized medium such as sand to form a fluidized bed and burns fuel or incineration materials in this fluidized bed, is capable of burning even relatively flame-retardant materials. Due to its good properties, it has recently been used in various fields. In this fluidized bed device, the heat transfer efficiency within the bed is very good, so heat transfer tubes such as superheating devices and evaporation tubes are placed inside the bed to recover heat, and when used as a boiler (fluidized bed boiler). There is. However, although fluidized bed boilers have good heat recovery efficiency, they have a problem in that load control is difficult. In other words, in order to form a fluidized bed, a constant amount of combustion air (fluidized air) must be supplied regardless of the load, and in order to continue operating the fluidized bed, the load must be kept almost constant. There is a need. For this reason, a method has been proposed and implemented in which the fluidized bed is divided into a plurality of cells and the load is controlled by adjusting the number of cells in operation. In this method, the damper is closed to stop the supply of air to the cell whose operation is to be stopped, thereby making the inside of the cell a static layer. However, even if the damper is doubled, some of the air that should be supplied to other cells will flow into the stopped cell, and the heat remaining in the medium that forms the stationary layer will cause the fuel remaining in the stationary layer to It was difficult to carry out effective load control due to so-called "oki" combustion. especially
When incinerating the soot dust collected in the combustion exhaust gas called EP ash, the EP ash melts and solidifies due to "oki" combustion, making it impossible to restart the cell.

<Objective of the Invention> The present invention provides a fluidized bed combustion apparatus in which a plurality of independent air chambers are provided under a perforated plate, and the fluidized bed formed on the perforated plate can be divided into multiple cells and operated.
We propose a fluidized bed combustion method and device that provides a structure in which cells corresponding to the air chambers that are out of operation maintain fluidity and prevent "boiling" combustion, and that allows easy load control operation using the device. The purpose is to

<Outline of Means> In short, the present invention provides a fluidized bed combustion apparatus in which a plurality of independent air chambers are provided under a perforated plate and a fluidized bed formed on the perforated plate is divided into a plurality of cells for operation. Air pipes connected to each of the plurality of air chambers are provided, and each of these air pipes is provided with two dampers in series that can be opened and closed for each air pipe, and the air pipes are connected to the pipes between the two dampers. A fluidized bed combustion apparatus and a combustion method therefor are characterized in that exhaust gas pipes are provided for guiding exhaust gas from the fluidized bed combustion apparatus, and each of these exhaust gas pipes is provided with a damper that can be opened and closed.

<Examples> Examples of the present invention will be described below with reference to the drawings.
In FIG. 1, a fluidized bed forming part of a fluidized bed combustion apparatus (hereinafter simply referred to as a fluidized bed boiler) 1 includes an air chamber 2a,
The fluidized bed is divided into four cells corresponding to the respective air chambers on the perforated plates 3a, 4a, and 5 to enable operation. Of these, 5 is a starting cell, and when the fluidized bed boiler is started, only this starting cell 5 is started, the heated medium is caused to flow into the other cells by overflow, etc., and the other cells are started one after another. Reference numeral 7 represents a heating device placed within the cell 2, and 8 and 9 represent evaporation tubes placed in the cells 3 and 4, respectively. 10 is a blower that supplies combustion air (fluidized air); 11 is a recirculation gas supply blower that recirculates and supplies combustion gas to the air chamber; and 12 is a control box that issues memory and command signals.

Two dampers that can be opened and closed are installed in series in the pipe line for each chamber that supplies combustion air to each air chamber, and a flow rate detector is installed downstream of this damper. An open circulation combustion gas supply pipe with an openable and closable damper for supplying combustion gas from line 18 is connected.

The load control method for this fluidized bed boiler will be described below.
Although the control can be performed manually, automatic control using the control box 12 will be explained as an example.

First, when the fluidized bed boiler 1 is operated at full load, the exhaust gas introduction pipes 13a, 13b, 13c, 13d connected to the exhaust gas recirculation fan 11
Dampers 14a, 14b, 14c, 14d provided in
is fully closed by a command signal from the control box 12. On the other hand, the dampers 16a, 16b, 16c, and 16d provided in the air supply pipes 15a, 15b, 15c, and 15d are fully closed, and the air chambers 2a and 16d formed at the bottom of each cell are
Combustion air is supplied into 3a, 4a, and 5a. The combustion air passes through the perforated plate 20 and forms a plurality of fluidized bed cells on the perforated plate 20. Intralayer heat transfer tubes placed in each cell recover heat from the fluidized bed, extract it as steam, and supply it to predetermined equipment. In this case, the control box 12 detects the amount of air supplied to each cell using the flow rate detectors F ₁ , F ₂ , F ₃ , F ₄ , and adjusts the flow rate adjustment dampers 17 a , 17 b , so that the amount of air supplied becomes a predetermined value.
Adjust 17c and 17d.

Next, when the load on the fluidized bed boiler is to be reduced, this is done by adjusting the number of cells 2 to 5 in operation. For example, when stopping the operation of the cell 3, the control box 12 fully closes the damper 16b and fully opens the damper 14c instead. As a result, a part of the combustion gas in the combustion gas pipe 18 reaches the recirculation fan 11 via the recirculation pipe 19, and further reaches the exhaust gas introduction pipe 1.
It reaches cell 3 via 3c. As a result, the fuel inside the cell 3 is fluidized by the recirculated combustion gas, and the fuel remaining in the layer is an inert combustion gas containing a large amount of _CO2 , so it is hardly combusted. As a result, the fluidized medium is not bound and solidified by the melted fuel due to "open" combustion. A NOx detector 21 is installed in the exhaust gas pipe 18 to detect the nitrogen oxide concentration in the exhaust gas, and this concentration is input to the control box 12. Based on the detection result, the control box 12 controls the combustion By adjusting the air supply amount, low o combustion can be achieved and the concentration of nitrogen oxides in the exhaust gas can be reduced.

By adjusting the number of operating cells as described above, the load of the fluidized bed boiler can be controlled.

<Effects of the Invention> By carrying out the first invention, it has become possible to perform effective load control operation that prevents the fuel remaining in the stationary layer from burning.

Further, with the device according to the second aspect of the invention, even cells that are not in operation can maintain a sufficiently flowing state, so that it is possible to rapidly respond to an increase in load, making load control easier.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view and a control system diagram of a fluidized bed boiler for carrying out the method according to the present invention. 1...Fluidized bed boiler (fluidized bed combustion heating device),
2a, 3a, 4a, 5a... air chamber, 10... blower for supplying combustion air, 11... blower for supplying recirculated combustion gas, 12... control box, 20... porous plate.

Claims (1)

[Scope of Claims] 1. A fluidized bed combustion apparatus in which a plurality of independent air chambers are provided under a perforated plate, and a fluidized bed formed on the perforated plate is divided into a plurality of cells for operation. Provide air pipe lines that connect to each air chamber,
There are two air pipes that can be opened and closed for each air pipe.
two dampers are each provided in series, and an exhaust gas pipe is provided for guiding the exhaust gas from the fluidized bed combustion apparatus to a pipe between the two dampers, and a damper that can be opened and closed is provided in each of the exhaust gas pipes. A fluidized bed combustion apparatus characterized by: 2. Air connected to each of the plurality of air chambers of a fluidized bed combustion apparatus that is provided with a plurality of independent air chambers under the perforated plate and is capable of operating the fluidized bed formed on the perforated plate by dividing it into a plurality of cells. pipes are provided, and two dampers that can be opened and closed for each air pipe are provided in series in each of these air pipes, and the exhaust gas from the fluidized bed combustion apparatus is guided to the pipe between the two dampers. A fluidized bed combustion apparatus is provided with pipes, each of which is provided with a damper that can be opened and closed, and the number of air supply pipes that supply combustion air to the air chamber is adjusted according to the load. The damper on the air chamber side of the two dampers installed in the air supply pipe where the supply of combustion air has been stopped is opened, the damper on the upstream side is closed, and the pipe between these two dampers is closed. A damper provided in the connecting pipe is opened to supply the combustion exhaust gas of the fluidized bed combustion apparatus, thereby maintaining the flow in the fluidized bed cell portion corresponding to the air chamber connected to the pipe. Fluidized bed combustion method.