JPS59109706A - Fluidized-bed combustion furnace - Google Patents

Abstract

PURPOSE:To facilitate the starting of fluidized bed and at the same time prevent the furnace from being burnt-out at its start. CONSTITUTION:Air chambers 4A, 4B and 4C, which are partitioned at equal space intervals by partition walls 3A and 3B, are formed beneath a perforated plate 2 arranged within a furnace body 1. Out of said air chambers, the partition wall 3A, which partitions the air chamber 4A provided for starting purpose, consists of a water tube wall. Furthermore, dams 5A and 5B are disposed in upright on the perforated plate 2 at the locations corresponding to said partition walls 3A and 3B. In order to start a fluidized bed, fluidizing medium such as sand or the like is charged only in a first partition 6A above the air chamber 4A and then air is supplied from a fan 7 to said air chamber 4A in order to fluidize the medium in the first partition 6A and simultaneously a starting burner 8 in a hot air furnace 20 is ignited so as to supply high temperature combustion gas in order to raise the temperature in the fluidized bed. In this case, because of being composed of water tube wall, no burn-out of the partition wall 3A of the air chamber 4A occurs inspite of being directly exposed to high temperature gas of 1,000 deg.C, for example, or above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed combustion furnace, and more particularly to a fluidized bed combustion furnace that facilitates the startup of the fluidized bed and prevents the furnace from burning out during startup.

When starting a fluidized bed, the same fluidized medium corresponding to the rated load is introduced into the furnace, and fluidized air (combustion air) is introduced from the bottom of the furnace to flow inside the bed. As the temperature increases, a method is adopted in which the bed temperature is raised using a starting burner. Specifically, a startup fuel such as heavy oil is used to raise the bed temperature, and when the bed temperature reaches the ignition temperature of the main fuel, such as pulverized coal, the main fuel is gradually switched to, and finally only the main fuel is used. Shift to steady operation. However, this method has the following problems.

First, the amount of fluidized medium corresponding to the rated load is a considerable amount, and even if start-up combustion is performed using air (usually cold air equivalent to room temperature) to fluidize this fluidized medium, it is difficult to easily perform start-up combustion due to the large amount of media. The bed temperature does not rise and a large amount of startup fuel is required. It is necessary to use fuel with good ignitability such as heavy oil or natural gas for this startup fuel, or all of these fuels are expensive, and the increased consumption of startup fuel increases the operating costs of the fluidized bed reactor. It will not have a major impact on

Next, in order to effectively utilize the heat in the fluidized bed, an evaporation tube is installed inside the bed.
Heat exchanger tubes such as superheater tubes may be installed, but since a certain amount of time is required for the feed water to be heated and steam to be generated, if the temperature in the layer rises and a certain period of time does not elapse, the superheater It is impossible to supply steam to the pipes, etc., and there is a risk that the superheater pipes will burn out during this period due to the lack of steam flow.

In order to prevent this, the air chamber under the perforated plate of the fluidized bed furnace is partitioned, and a dam is provided on the perforated plate to make the fluidized bed into multiple sections.After starting up one of the sections as the starting section, Attempts have been made to start the process by sequentially overflowing the fluidized medium at an elevated temperature into other adjacent compartments, but with this method,
It has been found that during startup, combustion gas from the startup burner is introduced into the startup section of the air chamber, causing the temperature of the partition wall of the air chamber to rise to over 1000°C, resulting in burnout. Ta.

An object of the present invention is to provide a fluidized bed combustion furnace that does not cause burnout 1B on the partition wall provided for startup in the air chamber below the perforated plate of the fluidized bed furnace.

The present invention provides a fluidized bed furnace in which an air chamber under a perforated plate of a fluidized bed furnace is partitioned, a dam is provided on the perforated plate to form a plurality of compartments, and one of the plurality of compartments is used as a startup compartment. , characterized in that the partition wall of the air chamber of the starting section has a water-cooled structure.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a sectional view of a furnace of a fluidized bed boiler device showing one embodiment of the present invention. Porous holes 4F provided in the furnace body 1
In the lower part of J, 2, air chambers 4A, 4B and 4C are formed, which are partitioned at equal intervals by partition walls 3A and 4B. Of these, the partition wall 3A that partitions the starting air chamber 4A is constituted by a water pipe wall. In addition, the partition wall 3
Weirs 5A and 5B are erected on the perforated plate 2 corresponding to A and 3B.

When starting the fluidized bed, a fluid medium such as sand is introduced only into the first section 6A at the top of the air chamber 4A, and air from the fan 7 is supplied to the air chamber 4A to cause the air inside the first section 6A to flow. While fluidizing the medium, the starting burner 8 in the hot air stove 20 is ignited to supply high temperature combustion gas and raise the temperature of the fluidized bed. At this time, the partition wall 3A of the air chamber 4A is, for example, 10'
Although it is directly exposed to high-temperature gas of OO'C or higher, it will not burn out because it is composed of water tube walls. When the temperature of the fluidized bed 6A rises to 500° C. to 600° C. or higher, main fuel, such as pulverized coal, is supplied from the fuel supply pipe 9A.

The temperature in the bed further increases as the main fuel burns, and when the temperature reaches a temperature that allows self-combustion of the main fuel, the starting burner 8 is stopped.

Once the fluidized bed in the first section 6A is started, a fluidized medium is newly supplied to continue combustion, and thereafter the second section 6B and the third section 6C are sequentially started.

That is, the high temperature fluid medium in the first section 6A is transferred to the dam 5A.
The main fuel is started to be supplied from the fuel supply pipe 9B, and a new fluidizing medium is further supplied to start up the second section 6B. Thereafter, the fuel supply pipe 9C is opened in the same manner, fluidized medium is added, and the third section 6C is activated. Once all the compartments have started up, the amount of main fuel supplied will be increased in response to the rise in bed height. Reference numeral 12 denotes an evaporator tube, which heats the feed water as the bed height increases, and is in a state where steam can be supplied to the superheater tube 13 until the bed height reaches the superheater tube 13 disposed at the top. Therefore, there is no risk that the superheater tube 13 will burn out. When the bed height reaches the bed height L1 of the rated load, the supply of the fluid medium is stopped and steady operation begins.

In the above embodiment, the partition wall 3A is a water pipe wall, but it is not particularly limited to this as long as it has a water-cooled structure.

According to the present invention, the partition wall of the air chamber into which high-temperature combustion gas directly flows at the time of startup is configured with a water pipe wall, thereby preventing the partition wall from being burnt out, and the startup section also allows the necessary minimum ratio to be maintained. There is an advantage that the fluidized bed reactor can be started using starting fuel.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a fluidized bed combustion furnace showing one embodiment of the present invention. 1... Fluidized bed furnace, 2... Perforated plate, 3A... Water tube wall, 5A, 5B... Weir, 6A... First section,
6B...Second section, 6C...Third section.

Claims (1)

[Claims] (1) A fluidized bed furnace in which the air chamber under the perforated plate of the fluidized bed furnace is partitioned, a dam is provided on the perforated plate to form multiple compartments, and one of the multiple compartments is used as the startup compartment. A fluidized bed combustion furnace characterized in that the partition wall of the air chamber of the startup section has a water-cooled structure. (2. The fluidized bed combustion furnace according to claim 1, wherein the water cooling structure is a water tube wall.