JPS62258912A - Fluidized-bed combustion furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that, during operation of a combustion furnace, a fluidized bed consisting of the active substance present inside the combustion furnace is in a fluidized state to the extent that it is exhausted together with the partial exhaust gas of i). A type of fluidized bed with a vertical combustion chamber in which the inert substances are separated and recycled from the flue gas, and a heat exchanger that absorbs heat from the fluidized bed material in which the furnace working medium is recycled. Combustion furnace (a fl
U.S. Pat. No. 4,111,158, for ash particles and unburnt combustible material, describes a combustion furnace of this type having two paths for recirculating fluidized bed material, including ash particles and unburned combustible material. There is. A cyclone #l #lFi is arranged in the first path, by means of which separator a large part of the particles discharged from the combustion chamber together with the flue gas are separated from the flue gas. The separated particles are re-fed into the combustion chamber3, and the aforementioned heat exchanger that utilizes the energy produced by the combustion forms part of a second path3, in which the fluidized bed particles are The fluidized layer is removed from the bottom of the combustion chamber, cooled by a heat exchanger existing outside the combustion chamber, and then re-supplied into the combustion chamber from the upper part of the combustion chamber. It differs from the combustion furnace used in technology in the following points. 'In the combustion furnace of the present invention, the combustion chamber is located in the upper furnace chamber (upper fu
The combustion chamber is formed of a lower reactor chamber and a lower reactor chamber, and combustion takes place within the reaction chamber. The reaction chamber is located at the lower center of the furnace chamber, and is much larger than the furnace chamber.
bstantially) have a small cross-sectional area.

The i-exchanger is installed in one or more vertical tubes adjacent to the reaction chamber, the top of which opens into the furnace chamber.

A number of important advantages provided by the present invention are described in the following overview of combustion furnace operation.

In the reaction chamber located at the bottom of the combustion chamber, most of the supplied combustible material is combusted by a flow-induction reaction. ``Combustion air is injected from the bottom of the reaction chamber, and its flow rate is such that most of the particles in the fluidized bed, including ash particles and unburned combustible materials,
The flow is so great that it is carried along with the flue gas to the furnace room above.・Based on the division of the combustion chamber, which is a feature of the present invention, into the reaction chamber located at the lower part and the furnace chamber located at the upper part, which is located at 11°1 and has a sufficiently large cross-sectional area compared to the reaction chamber, as described in 1 above. When gas flows from the reaction chamber to the furnace chamber,
A sudden drop in gas flow rate occurs.

As a result, the conveying force of the flue gas against the swirling particles is rapidly attenuated, and the swirling particles move outward toward the wall of the furnace chamber where the gas flow rate is zero or close to zero. The particles eventually fall into the pipe opening or openings and, after heat transfer to the working medium, are re-fed from the pipe bottom back into the core chamber bottom. Since the gas is largely free of hot particles, it is possible to place the heat transfer surface of the heat exchanger in the flue immediately after the furnace chamber. Thereby, the temperature of the flue gas is controlled by the temperature of the subsequently connected cyclone separator, which is essential for the cyclone separator in the aforementioned U.S. patent.
No fatigue-resistant coating is required, and the IW can be reduced to a level that can be manufactured using only steel materials.

As a result, on the one hand, it is possible to provide a gas discharge pipe in the center of the separator, the length of which can be adjusted to a preset degree of separation, resulting in a higher degree of separation; Lighter weight and lower cost production are realized.

The central reaction chamber of single or multiple tubes can be mounted with good thermal efficiency by using the common intermediate 81 at position 11i.

This results in a reduction in the thermal stress of the intermediate wall and a simplification of the construction.

In addition, since the temperature of the flue gas at the exit of the combustion chamber is relatively low, reinforcement with heat-resistant materials is generally not necessary, except for the reaction chamber. As a result, the heat storage capacity of the combustion furnace is reduced. This reduces the time required to start up operations and reduce the time required for cooling during interruptions in operation.In addition, the weight of the combustion furnace itself is reduced, so the weight of the furnace support structure and furnace base material is also reduced. be done.

The invention will now be explained in more detail with reference to the drawings.1 In the illustrated embodiment, the combustion furnace is described as a combustion furnace vessel with natural circulation, the combustion chamber l of the combustion furnace having a vertical and gas-tight tubular shape. It is surrounded by a wall, and its riser pipe contacts the upper drum 2 via a suitable pipe, as in the conventional case. The lower end of the riser tube is also connected to a distribution box 8+ not shown, the combustion chamber 1 is located coaxially with the upper section 3, hereinafter referred to as the furnace chamber of the combustion furnace, and in the middle, the lower part of the furnace chamber. It is divided into reaction chamber sections 4 of the combustion furnace where the bulk of the combustion takes place. The reaction chamber, which is open at the top towards the furnace chamber, has a considerably smaller cross-sectional area than the furnace chamber. In the illustrated embodiment, the cross-sectional area of the reaction chamber is about 25 times the cross-sectional area of the furnace chamber.

Two vertical tubes 5, the total cross-sectional area of which in the illustrated embodiment is substantially equal to the cross-sectional area of the reaction chamber 4, are arranged along two opposite side walls of the reaction chamber 4. The remaining three sides of each tube 5 are surrounded by a heat insulating outer wall as shown in FIGS. 1 and 12. The outer walls of the reaction chamber 4, two of which necessarily constitute the partition walls of the tubes 5, are formed as gas-tight tubular walls, the tubes being fed at the bottom from a distribution box, not shown. holder, expands outward at the top, and opens into the furnace chamber 3.
part of the vertical tubular wall.

As shown in FIGS. 1 and 2, the state of the piping at the transition from the reaction chamber 4 to the furnace chamber 3 is such that each tube 6 is connected to another tube 7, and every other tube is displaced in the vertical direction.
It is arranged like this.

At the same time, the sheet-like part of the tubular wall connecting to the following tube protrudes to the outside at the transition from the reaction chamber to the furnace chamber, so that a flow path for the particulate surface to pass between the reaction chamber 4 and the furnace The particulate matter formed between the walls of the chamber 3 is blown upwards into the reaction chamber 4 and then falls into the interior of the tube 5 due to the reduction in the gas flow rate in the furnace chamber 3.

Each of the tubes 5 is provided with an adjustable slide valve (not shown) at the bottom to control the amount of particulate matter recirculated to the bottom of the reaction chamber 4.1, FIG. Below reaction chamber 4, as best shown in
A ventilation chamber 8 is provided with an intake opening 9 for intake of flow and combustion air.

Air is blown into the reaction chamber 4 through the ventilation chamber 8 and the bottom of a conventionally used grate or nozzle. This not only improves combustion assistance, but also removes most of the particulate matter from the flue scum produced during combustion, which is carried away when the flue gas exits from the upper opening of the reaction chamber. (so-called gas electric transmission), which is at a flow rate that guarantees that it will be carried out.

Also shown schematically in FIG. 3 is an inlet pipe 31.12 for replenishing particulate combustible material, vortex material, which is lost during operation of the combustion furnace.

In the illustrated embodiment, the furnace chamber 3 has approximately the same height as the reaction chamber. Furnace chamber 3 has a sloping tubular wall at its top]
3 is present and is followed by this wall, which is substantially compared to the cross-sectional area of the remainder of the furnace chamber.
A flue gas outlet opening 14 with a narrow cross-sectional area is defined.

A short ascending conveyance path 15 and a fairly long downward conveyance path 6 are provided downstream of the discharge opening 4. Picture conveyance path 15.1
6 directly on the furnace chamber 3 fill 34 surface (i mm e
d1ate) installed.

The two channels 15 and 16 have heat transfer surfaces (c
The invection heat 5 surface) is installed in a manner well known per se, for example, an initial overheater, an air preheater or an ecotsuma surface (5, a flow path extending upwardly from the lower end of the gas passage 16). is connected to a cyclone separator 19, in which the majority of the particles remaining in the flue gas are separated from the gas and discharged into the discharge pipe 2.
0 into the container 2J, the collected particles are re-supplied in whole or in part via the return pipe 22 into one of the pipes 5 and/or removed from the system. The flue gas from which impurities (particles) have been removed in this way is transferred to the pipe 23.
It is then discharged from the separator. The tube 23 has a heat transfer surface (convex) additionally provided with flue gas as shown in FIG.
tion heat 5 surface) 24,
Further, the flue gas in the dust separator 25 is discharged into the chimney by a draft blower (not shown) connected to the dust separator 25, which is a bag filter or an electric precipitator.

The heat transfer surface in the aforementioned conveyance path
Besides the water flow tubular walls in the reaction chamber 4 and the furnace chamber 3, the combustion furnace also has a heat transfer surface 2 (1) arranged in the two tubes 5, best shown in FIG. This heat transfer surface shown is formed as a spiral tube and at least a part of it is exposed to the hottest part of the combustion furnace.Therefore, the combustion furnace supplies superheated steam to, for example, a turbo generator, etc. It is clear that if used as such, the entire heat transfer surface or a portion thereof constitutes the final stage superheater in the combustion furnace.

It has already been mentioned briefly that the recirculation of the particulate matter from the tube 5 into the reaction chamber 4 is controlled by an adjustable slide valve, which is configured to control the recirculation of the particulate matter in relation to the feed rate of combustible material. Control of the amount of heat absorption of the working medium in the thermal surface 26, reaction chamber 4
It is also used to control the temperature of the fluidized layer inside the tank.

As is known to some extent, it is also possible to control the steam temperature of connected turbines by water injection. The pressure of the steam is used as a control parameter to adjust the supply of combustible material and air.

When supplying a small amount, the amount of air required for combustion is larger than the amount required to sufficiently fluidize the particles in the reaction chamber 4 (
Under these circumstances, a portion of the flue gas is recycled to the reaction chamber via the bottom 10 of the reaction chamber.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the combustion furnace of the present invention, and Fig. 2 is a vertical partial sectional view taken along line I-I in Fig. 2; Figure 3 is a simplified diagram of the combustion furnace corresponding to Figure 1. In addition, in the symbols used in the drawing, 3 indicates the furnace chamber;
4 is a reaction chamber,] 9 is a cyclone separator, 17.24.2
6 is a heat transfer surface, and 25 is a dust separator. (5 other people) -1 j- l歿2

Claims (7)

[Claims] (1) A vertical combustion chamber (1) in which a vortex layer made of inert material existing inside the combustion chamber during operation of the combustion furnace is in a fluid state to the extent that a considerable portion of it is exhausted together with the exhaust flue gas. a heat exchanger (26) in which heat is maintained and inert material separated from the flue gas is recycled; A fluidized bed combustion furnace of the type having a combustion chamber (1), which absorbs The reaction chamber (4) is located directly below and in the center of the furnace chamber (3), and its cross-sectional area is considerably smaller than that of the furnace chamber, and the heat exchanger (26) is located near the reaction chamber (4). Fluidized bed combustion furnace, characterized in that it is installed in one or more adjacent vertical tubes (5), the tops of which open into the furnace chamber (3). (2) The fluidized bed combustion furnace according to claim 1, characterized in that the ratio of the cross-sectional areas of the furnace chamber (3) and the reaction chamber (4) is at least 3:1. Furnace. (3) In the fluidized bed combustion furnace according to claim 1 or 2, the furnace chamber (3) has a substantially constant flow rate up to the flue gas discharge opening (14) located at the top of the furnace chamber. A fluidized bed combustion furnace characterized by a furnace chamber having a cross-sectional area. (4) In the fluidized bed combustion furnace according to claim 3, a heat transfer surface (17) is installed inside the fluidized bed combustion furnace, and a conveyance path (16) extending downward and communicating with the furnace chamber is provided. The lower end of the conveyance path (16) is generally connected to the reaction chamber (4) and the vertical pipe (5).
) A fluidized bed combustion furnace characterized by being located at an open position. (5) In the fluidized bed combustion furnace according to any one of claims 1 to 4, the height of the reaction chamber (4) and the vertical pipe (5) is higher than that of the combustion chamber (1). A fluidized bed combustion furnace characterized by being approximately half of the total height. (6) In the fluidized bed combustion furnace according to any one of claims 1 to 5, the heat exchanger incorporated in the single or plural vertical pipes (5) is a final stage superheater. A fluidized bed combustion furnace comprising: (7) In the fluidized bed combustion furnace according to any one of claims 1 to 6, the reaction chamber (4) has no inserted heat exchange surface. Floor combustion furnace.