JPS5916645Y2 - Fluidized bed combustion furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a fluidized bed combustion furnace, and more particularly to a fluidized bed combustion furnace that allows the fluidized medium in the furnace to be uniformly and evenly delivered to a fluidized medium cleaning device.

Fluidized bed combustion furnaces are used to burn materials that are difficult to burn due to their relatively high moisture and ash content, such as wood bark.

Sand or the like is used as the fluid medium that forms the fluidized bed.

When burning a mixture of ash, gypsum, etc., some of the ash melts at high temperatures in a fluidized combustion furnace, and then cools to form clinker.

It also includes gypsum, which was originally mixed into the fuel.

Furthermore, there are foreign substances such as fine particles obtained by crushing a fluid medium such as sand into finer particles.

If a large amount of clinker, gypsum, or fine powder is contained in the fluidizing medium, there will be adverse effects such as hindering the fluidization and reducing combustion efficiency.

Such foreign matter must be constantly removed from the fluid medium.

The object of the invention is to provide a device for cleaning and removing foreign matter from a fluid medium.

A conventionally used fluidized bed combustion furnace is shown in FIG.

The fluidized bed furnace 1 has a fluidized medium bed 2 below.

A plurality of air diffuser tubes (manifolds) 3 and nozzles 4 are provided embedded in the fluidized medium layer 2.

Combustion and flow air is sent from the blower 11 through an air duct 12 to the manifold 3 and is ejected through nozzles 4 arranged on the manifold.

The fluidized medium layer 2 is fluidized by the action of the blown air.

Fuel such as wood bark, which is inputted from the fuel input port 13, is fluidized and combusted while coming into contact with the high-temperature fluidized medium.

The combustion gases are discharged from the furnace outlet 14.

At the bottom of the manifold 3, there is a conical fixed bottom plate (fixed cone) 30.

The fixed bottom plate is sloped to such an extent that the fluid medium can easily slide thereon.

Further below the fixed bottom plate 30, a conical vibrating bottom plate (vibration cone) 31 whose upper and lower sides are connected by a campus 32 is provided.

A slide damper 33 is attached to the bottom of the vibrating bottom plate 31.

When the slide damper 33 is kept open and the vibration cone 31 is vibrated, the fluid medium containing foreign matter moves downward.

The fluid medium flowing out from the slide damper 33 is carried out of the machine by a conveyor 34.

The particles are then separated into coarse particles and normal particles by a vibrating screen 35.

The normal particles are conveyed to the upper part of the furnace by the packet conveyor 36, and are thrown into the furnace again to be reused.

Coarse particles such as clinker and gypsum are discharged from the top of the screen as oversized particles.

In this way, lumps in which part of the ash contained in the fuel is melted and solidified, gypsum, etc. that are mixed in the fuel from the beginning can be continuously removed from the fluidizing medium.

Then, the clean fluidized medium can always be returned to the furnace without impairing the fluidity of the fluidized medium.

Such fluid medium cleaning devices still have drawbacks.

This means that the fluidized medium does not fall uniformly down the cone (inverted cone) at the bottom of the furnace.

The part of the fluid medium inside the cone that is in contact with the surface of the cone does not easily slip due to the frictional force with the cone. This is not an easy task because this part receives a load from above and is pressed against the surface of the cone. Doesn't slide down.

However, the central part far from the cone surface is extremely slippery.

Therefore, only the fluid medium near the center falls and the part near the cone surface is left behind.

In other words, a phenomenon similar to ant hell occurs.

In this case, the medium in the peripheral area near the cone surface remains stagnant, making it impossible to uniformly clean and recover the fluidized medium.

The above disadvantages are due to the fact that the cone is single and all the load is applied to the medium near the cone, which prevents this sliding movement.

This can be solved by doubling the cone.

Based on this idea, the present invention has a double cone, and the medium is dropped little by little from the upper cone to the lower cone.
This is a fluidized bed combustion furnace that allows the medium to slide down without accumulating on the lower cone, and evenly leads the fluidized medium to a fluidized medium cleaning device outside the furnace and circulates it. It is something to give.

Embodiments will be described below with reference to drawings showing embodiments.

FIG. 1 is a longitudinal sectional view of a fluidized bed combustion furnace according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of only the cleaning device, and FIG. 3 is an enlarged sectional view of the vibrating conveyor.

The fluidized bed furnace 1 has a fluidized medium bed 2 at the bottom.

A plurality of air diffusers (
A manifold) 3 and a nozzle 4 are provided.

Combustion and flow air is sent from the blower 11 to the manifold 3 via an air duct 12.

Air flows from nozzle 4 on manifold 3 to fluidized medium layer 2.
is injected into the.

The jet air causes the fluid medium to flow vigorously.

The fuel injected from the fuel inlet 13 is fluidized and combusted while contacting the high-temperature fluidized medium.

The combustion exhaust gas is discharged from the furnace outlet 14.

Below the manifold 3, double inverted conical bottom plates (cones) are fixed at regular intervals.

A novel feature of the present invention is that the fluidized medium layer is received by a double cone.

A large number of notched holes 15 are bored in the upper cone 5.

The fluid medium falls through the cutout hole 15 onto the lower cone 6.

The fallen fluid medium flows down along the slope of the lower cone 6 and reaches the slide damper 7 at the center of the lower part.

The size of the notch hole 15 may be any size that does not hinder the passage of foreign matter in the fluid medium.

The shape is not limited to circular, but may be polygonal or slit-shaped.

The weight of the fluidized medium layer containing foreign matter is applied almost evenly over the entire surface of the upper cone 5.

The notched holes 15 are arranged in a suitable distribution over the entire surface of the upper cone 5, so that the fluid medium evenly falls from the entire surface of the upper cone 5 to the lower cone 6.

The lower cone 6 is fixed to the upper cone 5 via a distance piece 16 provided to maintain the distance between the lower cone 6 and the upper cone 5.

The flowing medium that has fallen onto the lower cone 6 is no longer under the load of the flowing medium layer.

This is because it does not form a thick layer.

The unloaded medium moves along the slope of the lower cone 6,
It flows smoothly down to the center.

The inclination angle of the lower sawn 6 is such that the fluid medium can flow smoothly under its own weight.

By forming a double cone in this way, the fluid medium containing foreign matter can be taken out evenly and smoothly without requiring any external movement (for example, vibration, etc.).

As shown in FIG. 3, the vibrating conveyor 8 is fixedly installed directly below the slide damper 7 at the lower end of the center of the lower cone.

The fluid medium containing foreign matter discharged from the slide damper 7 passes through the canvas 24 and is received by the vibrating conveyor 8.

The vibrating conveyor 8 is sealed by an outer case and has one end protruding outside the furnace.

Inside the vibrating conveyor 8, a screen 9 with a suitable mesh is stretched in the longitudinal direction.

The entire vibrating conveyor 8 reciprocates in the longitudinal direction.

The fluid medium moves gradually outwardly over the screen 9.

Coarse particles larger than the mesh proceed directly onto the screen 9 and are discharged from the outlet 21.

The fine particles passing through the mesh are discharged from the lower outlet 22 and conveyed to the packet conveyor 10.

This is a particle with normal particle size.

The particles fly up inside the vibrating conveyor due to the vibration, and are sucked by the suction fan 17 through the suction port 23 and the duct 19.

The fine particles are sent from the suction fan 17 to the filter 18,
It is collected here.

The vibrating conveyor 8 is elastically supported by a leaf spring 25.

The drive unit 26 of the vibrating conveyor 8 converts the rotational motion of the motor into a reciprocating motion in the lateral direction using a cam or a crank mechanism, thereby reciprocating the vibrating conveyor in the longitudinal direction.

In this way, the vibrating conveyor 8 can separate the fluidized medium in the furnace into three types: coarse particles, fine particles, and fine powder while conveying the fluidized medium inside the furnace to the outside of the furnace.

In this example, there is only one screen, but if a plurality of screens are provided to create a multi-stage conveyor, particles can be classified into even more particles.

Now, the fluid medium discharged from the outlet 22 of the vibrating screen 8 does not contain foreign matter such as coarse particles (clinker, etc.) or fine powder.

Then, it is transported to the upper part of the furnace by the packet conveyor 10 and fed into the furnace again.

It is used again as a fluidizing medium in the furnace.

What is discharged from the coarse outlet 21 of the vibrating screen is clinker lumps, stones, etc.

Since this is a foreign object, it is removed from the furnace.

The fine particles are flying in the form of dust in the internal space of the sealed vibrating conveyor 8.

This is sucked by the fan 17 and collected by the filter 18.

This includes particles such as sand and other fluids that have been broken down during the flow, and dust generated by combustion.

In this way, foreign matter such as hard lumps made by melting part of the ash contained in the fuel, gypsum mixed in the fuel from the beginning, fine particles such as fragments of the fluidizing medium, and dust can be removed.
It can be continuously removed from the fluid medium.

The fluidized medium from which foreign matter has been removed is returned to the furnace and used repeatedly.

As explained in detail above, this invention doubles the bottom plate,
A large number of notch holes 15 are provided in the upper bottom plate, and the notch holes 1
Since the fluidizing medium is allowed to fall from step 5 to the lower bottom plate, (1) the fluidizing medium is removed from the entire surface of the upper bottom plate at an almost uniform speed, and the ant hell phenomenon does not occur.

Therefore, the process of circulating (cleaning, reintroducing) the fluidized medium is carried out almost uniformly for all the media.

There is no stagnation in the periphery.

(2) On the bottom plate at the bottom, the media falling from the top slide down one after another, so there is no stacking up.

Therefore, the medium will not stick to the bottom due to pressure from above.

The media flows smoothly to the center without any stagnation on the bottom bottom plate.

There is no need to apply vibrations to move it.

This is a useful idea.

Note that the upper cone 5 is not necessarily required to have a conical shape.

This is because the fluid medium does not need to flow to the center of the upper cone 5, but only needs to fall through the cutout hole 15 onto the lower cone 6.

However, the lower cone 6 must be inclined.

In order to narrow the space between the upper cone 5 and the lower cone 6 and increase the effective capacity of the fluidized bed furnace, it is advantageous to make the upper cone 5 have the same inverted conical shape as the lower cone 6.

When there is no such requirement, the upper cone 5 may be a flat plate.

The lower cone 6 only needs to have an inclination, and instead of an inverted conical shape, it can be arbitrarily selected such as an inverted circular pyramid, an inverted square pyramid, etc., and an inverted conical shape is sufficient.

Also, the slide damper 7 can be replaced by other suitable evacuation devices.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a fluidized bed combustion furnace according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of the cleaning device. Figure 3 is an enlarged sectional view of the vibrating conveyor. FIG. 4 is a longitudinal sectional view of the entire conventional fluidized bed combustion furnace. 1...Fluidized bed furnace, 2...Fluidized medium bed,
3... Diffusion pipe, 4... Nozzle, 5...
... Upper cone, 6 ... Lower cone, 7.
... Slide damper, 8 ... Vibration conveyor, 9 ... Screen, 10 ... Packet conveyor, 11 ... Blower, 12 ...
... Air duct, 13 ... Fuel inlet, 14
... Furnace outlet, 15 ... Notch hole, 16
... Distance piece, 17 ... Fan, 18 ... Filter 19 ... Air duct.

Claims (1)

[Scope of utility model registration request] In a fluidized bed combustion furnace in which a fluidized bed 2 is sequentially taken out of the furnace from the bottom of a fluidized bed furnace 1 in which an appropriate number of air diffusers 3 are arranged, and is returned to the furnace after being treated with a cleaning device, An upper cone 5 having a number of notched holes 15 large enough to allow foreign matter in the fluidized medium 2 to pass through the bottom of the fluidized bed combustion furnace, and an inverted conical shape provided below the upper cone 5 at regular intervals. The lower cone 6 has a double furnace bottom, and a damper 7 for discharging the fluidized medium 2 is provided at the lower end of the inverted conical lower cone 6.
A fluidized bed combustion furnace characterized by being provided with.