JPS6383507A - Fluidized-bed combustion equipment - Google Patents

Abstract

PURPOSE:To increase the combustion efficiency of a fluidized-bed combustion equipment, and to decrease the consumption rate of coal by efficiently utilizing limestone, by providing a pulverizer which pulverizes small grains discharged from a discharge device, and a hopper which re-stokes the pulverized particles into a reaction furnace. CONSTITUTION:A cyclone 12 separates solid content such as coal ashes, unburned coal, and limestone from combustion exhaust gas containing fine particles. The solid content is returned to a fluidized bed 4 through a pulverized particle circulating pipeline 13. The unburned coal and pulverized particle circulating pipeline 13. The unburned coal and limestone are finely pulverized by a pulverizer 16, stored in a hopper 17, thrown down by a rotary valve 18 by a specified quantity, and is fed back to the fluidized bed 4 by an air conveyor 19. The coal can be burned completely, because the unburned coal content is returned to the furnace after it is pulverized and is made easy to be incinerated. As a result the combustion efficiency is increased, the reaction efficiency is also increased, and the consumption rate of coal can be decreased by the effective utilization of limestone.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fluidized bed combustion apparatus used in a 9-coal-fired boiler and a coal gasifier.

[Conventional technology]

A conventional fluidized bed combustion apparatus will be explained based on FIG. A hearth 2 made of a perforated plate is attached to the lower part of the furnace body 1. The lower part of the hearth 2 is a wind box 3, and the upper part of the hearth 2 is a fluidized bed 4 made of a fluidized material such as sand, coal, and limestone. ing. A freeboard section 5 is formed above the fluidized bed 4.

Nine coal dispersers 6 are provided in the furnace body 1 above the fluidized bed 4, and the nine coal dispersers 6 communicate with the lower part of the coal supply hopper 7. 9 Furnace body 1 located at approximately the same height as lime disperser 6
A limestone chute 9 connected to the lower part of the two limestone supply hoppers 8 is opened. Furthermore, a secondary air nozzle 1° is provided in the freeboard portion 5 of the furnace body 1. A convection heat transfer device 11 such as a superheater 2 and a economizer is disposed in a flue connected to the upper part of the furnace body 1, and the flue is connected to an inlet of a cyclone 12. A particle circulation line 13 opened at the fluidized bed 40 portion of the furnace body 1 is connected to the solid content outlet of the cyclone 12.An ash removal chute 14 is connected to the fluidized bed 4 portion of the furnace body 1.
is provided in the fluidized bed 4.

An intralayer heat transfer device 15 such as a superheater or an evaporator is arranged.

Sand is supplied to the upper part of the hearth 2, coal with a diameter of 8 to 25 mm is further supplied by a coal disperser 6, and limestone is supplied from a limestone sheet 9, and main air is blown from the wind box 3 through the hearth 2. , to fluidize the fluid material.

The fluidized coal is combusted by main air, and 70
A fluidized bed 4 at a temperature of 0 to 900°C is formed. At this time, the coal stone in the fluidized bed 4 and the generated SOX react and are desulfurized. Combustion in the fluidized bed 4 occurs under air-deficient conditions; 1. Part of the coal becomes flammable gas; 9. The particles are sent to the freeboard section 5 together with the scattered particles. In the freeboard section 5, the secondary air supplied from the secondary air nozzle 10 is
−−゛ −The flammable gas burns. The scattered particles and combustion exhaust gas pass through the flue, heat the fluid in the convection heat transfer device 11 along the way, and are sent to the cyclone 12. In the cyclone 12, the combustion exhaust gas containing fine particles is separated into solid components such as 1 coal ash, 1 unburned coal, and 1 coal stone, and the solid components are returned to the fluidized bed 4 via the particle circulation line 13.

From the take-out chute 14, fluidized materials such as coal ash (9), unburnt coal (2) and limestone (2) are discharged to the outside of the furnace body 1 as discharge ash in order to keep the height of the fluidized bed 4 constant.

[Problem that the invention seeks to solve]

When high ash coal is combusted or when two-stage combustion is performed, the unburned content of the ash discharged from the take-out chute 14 increases, resulting in a decrease in combustion efficiency. This is because when high ash coal is burned, residual ash in the fluidized bed 4 increases.

This is because the residence time of particles in the furnace decreases, and the two-stage combustion process is caused by particles not being completely combusted in the fluidized bed 4 during the residence time in the furnace when the air ratio in the furnace is low, and as discharged ash. This is because it is discharged outside the furnace.

When performing in-furnace desulfurization, not all of the limestone accumulated in the fluidized bed 4 and discharged does not react, but only about 10 to 30% reacts. This is because qaO in limestone is SOl
The reaction to form Ca5Os occurs from the limestone surface and does not completely react inside the limestone.

Therefore, it is necessary to introduce more limestone into the fluidized bed 4 than the theoretical value to compensate for the amount of unreacted limestone discharged from the furnace.

Requires a lot of limestone.

[Means for solving problems]

The present invention aims to increase combustion efficiency and reduce the amount of limestone used by effectively utilizing limestone.The present invention has been developed to provide a reactor in which a fluidized bed is formed, a fuel supply machine that supplies solid fuel into the reactor, and two reactors. An air supply machine that supplies combustion air, an exhaust machine that discharges some of the particles that make up the fluidized bed formed in the reactor, and maintains the height of the fluidized bed at a constant level; and a crusher to crush the particles.

A fluidized bed combustion apparatus is provided that is equipped with a re-injection machine that re-injects particles pulverized by a pulverizer into a reactor.

[For production]

The ash extracted from the furnace is crushed to reduce the particle size of the unburned coal particles contained in the extracted ash to make it easier to burn, and the unreacted part inside the limestone is exposed to the entire surface to form a reaction part. and then recycled into the fluidized bed. A hearth 2 made of a perforated plate is attached below the furnace body 1, and a wind box 3. In the upper part of the hearth 2, a fluidized bed 4 made of a fluidized material such as sand, coal, and limestone is formed. A freeboard section 5 is formed above the fluidized bed 4.

Nine coal dispersers 6 are provided in the furnace body 1 above the fluidized bed 4, and the nine coal dispersers 6 communicate with the lower part of the coal supply hopper 7. 2 Furnace body 1 located at approximately the same height as coal disperser 6
A limestone shade 9 connected to the lower part of the limestone supply hopper 8 is open. Furthermore, a secondary air nozzle 10'' is provided in the 7 reheat section 5 of the furnace body 1.

A convection heat transfer device 11 such as a superheater 2 and a economizer is arranged in a flue connected to the upper part of the furnace body 1, and a cyclone 12 is connected to the flue.
It is connected to the entrance of the A particle circulation line 13 opened at the fluidized bed 40 portion of the furnace body 1 is connected to the solid content outlet of the cyclone 12 . An ash take-out shade 14 is provided in the fluidized bed 40 portion of the furnace body 1, and the downstream end of the take-out shade 14 is connected to the inlet of a crusher 16 such as a hammer crusher, roll mill, or ball mill. The outlet of the crusher 16 communicates with a hopper 17, and the outlet of the hopper 17 communicates with an air conveyor 19 via a chute with a rotary pulp 18 in the middle. An input line 20 is connected to the outlet of the air conveyor 19.

The charging line 20 is connected to the fluidized bed 4 portion of the furnace body 1 and is open.

Moreover, in the fluidized bed 4, there is an intrabed heat transfer device 1 such as a superheater or an evaporator.
5 is placed.

Sand is supplied to the upper part of the hearth 2, coal with a diameter of 8 to 251 RrIL is supplied by a coal disperser 6, and limestone is supplied from a coal stone shade 9, and main air is blown from the wind box 3 through the hearth 2. to fluidize the fluidized material. The fluidized coal is subjected to main air combustion and heated to a temperature of 700 to 900°C.
A fluidized bed 4 is formed. At this time, the coal stone in the fluidized bed 4 reacts with the generated SOx and is desulfurized.

Combustion in the fluidized bed 4 occurs in an air-starved state.

A portion of the coal is sent to the freeboard section 5 together with flammable gas and scattered particles. In the freeboard section 5, combustible gas is burned by secondary air supplied from the secondary air nozzle 10. Scattered particles and combustion exhaust gas are removed through the flue.

On the way, the fluid in the convection heat transfer device 11 is heated and the cyclone 12
sent to. In the cyclone 12, the combustion exhaust gas containing fine particles is separated into solid components such as 2 coal ash, unburned coal and 1 coal stone, and the solid components are returned to the fluidized bed 4 via the particle circulation line 13.

From the take-out shade 14, fluidized materials such as 9 coal ash and 1 unburned coal and 1 limestone are taken out to the outside of the furnace body 1 in order to keep the height of the fluidized bed 4 constant.

It is sent to a crusher 16. A crusher 16 brings out the unreacted portion of the unburned limestone to the surface. The finely pulverized fluid material is stored in the hopper 17.

A predetermined amount is cut out by a rotary valve 18 and returned to the fluidized bed 4 via an input line 20 (by an air conveyor 19). The unburnt coal returned to the fluidized bed 4 has a small particle size and is quickly combusted, becomes fly ash, scatters in the freeboard section 5, and passes through the cyclone 12 to the downstream side of the cyclone 12. The dust is collected by a dust collector and taken outside. In addition, the limestone 9 is also crushed into small pieces and an unreacted portion is exposed on the surface of the limestone 9, so that it reacts with SO in the fluidized bed 4. Limestone was scattered along with fly ash, and cyclone 12
The particle size of the salt that is no longer collected is crushed repeatedly, so
Finally, like fly ash, it is collected in a dust collector on the downstream side of the cyclone 12 and taken out to the outside.

According to this device, unburned coal is pulverized to make it more combustible and then used for combustion, making it possible to completely burn one piece of coal.
Good combustion efficiency.

Also, crush the limestone and expose the unreacted parts to the surface.

By reacting, the υ2 reaction efficiency also increases.

It is possible to reduce the amount of limestone used through effective use.

〔Effect of the invention〕

According to the present invention, the unburned coal taken out from the fluidized bed is crushed into small pieces, made more combustible, and returned to the fluidized bed, so that all of the lime is used for combustion, increasing the combustion efficiency, and making it more combustible. Limestone is crushed and unreacted parts are brought to the surface and returned to the fluidized bed, so 1. Limestone can be used effectively 2.
The amount of limestone used can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an embodiment of the present invention, and FIG. 2 is a system diagram of a conventional fluidized bed combustion apparatus. 1... Furnace body, 2... Hearth, 4... Fluidized bed, 14
...Take-out chute, 16...Crusher, 17...Hopper. 18... Rotary pulp, 19... Air conveyor. 20...Input line.

Claims (1)

[Claims] A reactor in which a fluidized bed is formed, a fuel supply machine that supplies solid fuel into the reactor, an air supply machine that supplies combustion air into the reactor, and a fluidized bed formed in the reactor. In a fluidized bed combustion apparatus having an ejector that ejects some of the particles constituting the bed and maintains the height of the fluidized bed constant, a pulverizer that pulverizes the particles discharged by the ejector, and the same pulverizer. A fluidized bed combustion apparatus comprising: a re-injector for re-injecting the pulverized particles into the reactor.