WO1999043985A1

WO1999043985A1 - Fluidized bed gasification furnace

Info

Publication number: WO1999043985A1
Application number: PCT/JP1999/000946
Authority: WO
Inventors: Norihisa Miyoshi; Seiichiro Toyoda; Daisaku Fukuoka; Takashi Imaizumi; Shinichirou Chiba
Original assignee: Ebara Corporation
Priority date: 1998-02-27
Filing date: 1999-02-26
Publication date: 1999-09-02
Also published as: AU2641999A; DE69926217D1; CN1295661A; EP1058051A4; CN1239841C; EP1058051A1; EP1058051B1; DE69926217T2

Abstract

A fluidized bed gasification furnace capable of quickly discharging unburnt matter contained in fuel along with a fluid medium; specifically, a fluidized bed gasification furnace using a fluidized bed reaction device, comprising a discharge port (16) for a fluid medium disposed in the vicinity of the surface of the fluidized bed and connected with fluid medium discharging chutes (20a to 20d) extending downward, and a gas blow-out device (13) disposed below the chutes.

Description

Description Fluidized bed gasifier Technical field

The present invention relates to a fluidized-bed gasifier, and more particularly to a fluidized-bed gasifier characterized by discharging a fluidized medium.

A fluidized bed (bed) is a fluidized bed fluidized by supplying gas from under a particle packed bed filled with several tens to several millimeters of fluidized medium particles such as silica sand and iron oxide. A fluidized bed (layer) is formed. A fluidized bed reactor is used to accelerate the chemical reaction by utilizing the fluidity, uniformity, heat capacity, and surface area of the fluidized bed (layer). It is intended to be performed stably and homogeneously, and has been used in catalytic cracking furnaces for petroleum refining, combustion furnaces and incinerators for solid fuels such as coal, and has many achievements. Background art

Fluidized bed gasifiers have excellent mixing characteristics and heat transfer characteristics due to the fluidized medium. Compared to a gas-bed reactor, there are advantages such as less restrictions on the size and properties of the fuel that can be charged, but fluidized media and fuel The disadvantage is that the operating temperature must be lower than that of a pneumatic bed reactor in order to prevent the ash content inside from melting and adhering to each other at high temperatures and obstructing the flow. The temperature range is about 900 ° C or less when using coal as fuel, and about 600 to 800 ° C when using waste as fuel, depending on the nature of the waste. If the waste contains Al-Li metal, it needs to be lower.

Pyrolysis of waste and coal at relatively low temperature ■ Problems and problems when gasifying There is tar generation. In general, tar evaporates in the temperature range of about 600 ° C, but it liquefies when the temperature drops to below 200 ° C, and its stickiness causes various problems in particle handling. _t also can cause, characterized in fluidized-bed gasification furnace, a large amount of Chiya one in the furnace are retained, when withdrawing incombustible like from the layer, the hot Chiya one Combustion on contact with air and high temperatures can generate cleaning power.

As described above, the fluidized-bed gasification reactor has the feature that there are few restrictions on the size of the fuel that can be input and the properties of the fuel.However, in the case of a fuel containing incombustible substances such as coal and waste, the If the particles are charged as they are, the incombustibles remaining in the reactor will also increase, and it will be necessary to discharge them from the reactor in some way. However, it is very difficult to withdraw a fluid medium at a high temperature of 500 ° C. to 600 ° C. from a fluidized bed even in a normal pressure reactor because of the high temperature. In gasifiers operated under pressure, it is almost impossible. However, even if the fluidized medium could be extracted from the fluidized bed, the heat loss due to the extraction of the high-temperature fluidized medium would be large, reducing the heat utilization efficiency. A large amount of dust mixed in the medium may burn when it comes into contact with air, resulting in unexpected trouble.

When the fluid medium is cooled down, the vaporized tar liquefies and may cause various troubles.Therefore, the fuel is finely crushed and injected so that it is not necessary to remove the incombustibles. I had to do it, and I couldn't take full advantage of the special features of the fluidized bed reactor. Disclosure of the invention

The present invention has been made in view of the above-mentioned conventional technology, and has a large amount of fuel that can be charged. The purpose of the present invention is to provide a fluidized bed gasifier with excellent operability that can safely operate not only at normal pressure but also under high pressure, while taking advantage of the characteristics of fluidized bed reactors that have few restrictions on size and properties. And

In order to achieve the above object, the present invention provides a fluidized-bed gasification furnace using a fluidized bed reactor, wherein a fluidized medium discharge shut is provided near a floor of the reactor, It is characterized by providing a gas blowing device below the gate.

In the fluidized-bed gasification furnace, a device for mechanically extracting the fluidized medium is provided in the vicinity of the lowermost portion of the fluidized medium discharge shutter, and a screw conveyer is used as the device. Yeah.

The fluidized medium discharge Shiyu over preparative may that that have a balloon device for a gas to the bottom, these gas blowing device is a gas vapor or blowing out using a gas containing no co ₂ or oxygen be able to.

Further, the fluidized bed reactor used in the present invention is preferably divided into units according to functions, and can be easily adapted to fuels having different properties by changing the combination of the units. BRIEF DESCRIPTION OF THE FIGURES

1A, 1B, and 1C are cross-sectional views showing the structure of a cylindrical fluidized-bed gasification furnace showing an example of the fluidized-bed gasification furnace of the present invention. 1B is a sectional view taken along line AA of FIG. 1A, and FIG. 1C is a sectional view taken along line BB of FIG. 1A.

2A, 2B, and 2C are cross-sectional views showing the structure of a rectangular-type fluidized-bed gasifier showing another example of the fluidized-bed gasifier according to the present invention. Fig. 2B is a cross-sectional view taken along the line A-A of Fig. 2A, and Fig. 2C is Fig. 2 FIG. 2 is a sectional view taken along line B-B of A.

FIG. 3 is an overall configuration diagram showing an example of components around a gasifier according to the present invention.

FIG. 4 is an overall configuration diagram showing another example of components around the gasification furnace of the present invention.

FIG. 5 is an overall configuration diagram showing still another example of components around the gasification furnace of the present invention.

FIG. 6 is a longitudinal sectional view showing a modified example of the fluidized bed gasification furnace of the present invention.

FIG. 7 is a longitudinal sectional view showing a modified example of the fluidized bed gasification furnace of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

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

FIGS. 1A, 1B, and 1C are cross-sectional views showing the structure of a cylindrical fluidized-bed gasifier showing an example of the fluidized-bed gasifier of the present invention. Fig. 1A is a longitudinal sectional view of a fluidized bed gasifier, Fig. 1B is a sectional view taken along line A-A of Fig. 1A, and Fig. 1C is a sectional view taken along line B-B of Fig. 1A.

The fluidized bed gasifier using the cylindrical fluidized bed reactor shown in Fig. 1A to Fig. 1C is composed of a fluidized bed unit 1, a furnace bottom unit 2, a medium discharge unit 3, a freeboard unit 4, And a reflector unit 5. In the present invention, the fluidized bed reactor comprises a fluidized bed unit 1, a furnace bottom unit 2, and a medium discharge unit 3. Each adjacent unit is connected by a flange. Inside the fluidized bed unit 1, there is provided a fluidizing gas dispersing device 6 having a conical upper surface, and a large number of fluidizing gas dispersing devices are provided on the upper surface of the fluidizing gas dispersing device 6. A nozzle 7 is provided. The fluidized bed unit 1 and the inside of the unit below the fluidized bed unit 1 are filled with a fluidized medium 11, and the fluidized medium above the fluidized gas dispersion device 6 is a fluidized gas dispersion nozzle. It is fluidized by the fluidizing gas blown out from 7 to form a fluidized bed 8. Further, inside the fluidizing gas dispersing device 6, an air header 9 is divided into at least two or more and is built in, and the velocity of the fluidizing gas blown out from the fluidizing gas dispersing nozzle 7 is controlled in the peripheral portion. By making the blowing speed different so that the fluid flow becomes relatively faster than the central part, the internal swirling flow 12 of the fluidized medium is formed in the fluidized bed. The temperature of the fluidized medium above the fluidizing gas dispersing device 6 is maintained between 400 ° C. and 100 ° C., preferably between 500 ° C. and 800 ° C.

Inside the fluidized bed unit 1, above the periphery of the fluidizing gas dispersion device 6, there is provided an outlet 16 for the fluidized medium directed outward. A gap 20 between the fluidizing gas dispersion device 6 and the inner wall of the fluidized bed unit 1 is formed below the outlet 16, and this gap 20 is used as a discharge medium for the fluidized medium. This gap 20 is divided into four shoots 20a to 20d by a support 10 that fixes the fluidizing gas dispersion device 6 and the inner wall of the fluidized bed unit 1. . A pipe for supplying a fluidizing gas from outside the fluidized bed unit 1 to the air header 9 may be provided inside the support 10.

It is preferable that each shoot 20a to 20d be in contact with the entire side surface of the fluidizing gas dispersing device 6 in order to prevent accumulation of incombustibles in the fluidized bed 8. In that case, the upper end of the support 10 necessarily has a mountain shape, and the top of the mountain has an acute angle. When the piping is to be built in the support 10, the support 10 needs to have a certain width, so that the shape of the support 10 expands downward. The shape must be reduced, and the circumferential width of each shoot 20a to 20d will be reduced. But However, in each of the shots 20a to 20d, it is necessary to prevent the horizontal cross-sectional area from gradually becoming narrower in the downward direction in order to avoid blockage due to incombustibles inside. Therefore, in the present gasification furnace, the lower side surface 6a of the fluidized gas dispersion device 6 is inclined toward the center line as it goes downward, so that the radius of each shot 20a to 20d is reduced. The dimension in the direction is increased toward the bottom to prevent the horizontal cross-sectional area from decreasing.

Gas blowout nozzles 13 are provided vertically below each shoot 20a to 20d, and the inside of the shoot is purged with steam or an inert gas to diffuse tar and oxygen. To prevent fluid flow and to fluidize the fluid medium violently to eliminate clogging of the shoot.

A media discharge unit 3 is connected to the lower side of the furnace bottom unit 2, and the inner surface of the furnace bottom unit 2 in the gasification furnace is adapted to the size of the inlet of the medium discharge unit 3. Inclined and narrowed as a whole. If non-combustibles that could form a bridge due to such squeezing must be discharged, for example, incombustibles such as wire, the vertical wall of the straight plate can of course be used. Good or eccentric, vertical and inclined parts may be provided.

A medium discharge device 15 is provided below the medium discharge device unit 3. In this gasifier, a screw conveyor is used as the medium discharge device 15, but depending on the properties of incombustible materials, a discharge device that can discharge in the horizontal direction like a chain conveyor is used. May be. Further, in the present gasification furnace, the medium discharge device 15 is installed horizontally in the horizontal direction, but it can be tilted up and down.

In addition, at the bottom of the media ejection unit 3, A gas blowing nozzle 14 is provided below. In the case of the present gasification furnace, the number of nozzles 14 for blowing out this gas is one, but this nozzle extends over the entire diameter of the connection portion between the medium discharge unit unit 3 and the hopper unit 2 under the furnace. Since the purpose is to spread the gas, the number may be increased if necessary. Since the concentration of incombustibles can be expected due to the wind power sorting effect of the gas blown from the gas blowout nozzles 14, the amount of discharged fluid medium is reduced, and the amount of heat taken out is also reduced.

If the nozzle 1 4 blowout gas is blown gas 3 0 containing no steam or CO _2, or oxygen, which contains carbon particles in liquidity medium in shoe one DOO When blowing steam and C 0 ₂ is The cooling effect can be further enhanced by the above-mentioned endothermic reaction.

C + H ₂₀ → CO + H ₂

C + C 0 ₂ → 2 CO

Of course the same effect can be obtained even by blowing the steam or C 0 ₂ from the nozzle 1 3 gas blowing.

When steam is blown from the nozzles 13 and 14, the temperature of the steam to be blown must be at least not lower than the saturation temperature at the operating pressure of the gasifier. It is necessary to prevent dew condensation by keeping the temperature of the media discharge device etc. below the dew point by keeping it warm or performing heat tracing as necessary.

The gasifiers shown in Fig. 1A to Fig. 1C are united for each part in charge of each function, but of course, they may be manufactured integrally. In particular, in the case of large furnaces, each part is large and sufficient maintenance space is available, and there is no need to divide and inspect each unit, so they can be manufactured integrally. However, when used under pressure, the volume will be Since part inspections are becoming more difficult, unit-split types such as those shown in Figs. 1A to 1C may be effective.

Another advantage of the unit split structure is that the structure can be easily changed depending on the fuel properties. For example, for fuels that are difficult to gasify and require a long residence time in the fluidized bed, to increase the bed height, the diffuser unit 5 and the fluidized bed unit as shown in Fig. 6 are used. A straight pipe section 1a is added between the points (1) and (2). In addition, for fuels that require a long freeboard residence time due to low specific gravity and low in-layer residence ratio, a shape that bulges out slightly above the flange as shown in Fig. 7 is used. Use the freeboard unit 4 whose internal volume has been increased. In this way, as shown in FIGS. 6 and 7, by modifying only necessary parts, various fuels can be easily handled without modifying the entire fuel.

2A, 2B, and 2C are cross-sectional views showing the structure of a rectangular fluidized-bed gasifier showing another example of the fluidized-bed gasifier according to the present invention. 2A is a vertical cross-sectional view of the fluidized bed gasifier, FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 2C is a cross-sectional view taken along line BB of FIG. 2A.

2A to 2C, the same reference numerals as those in FIGS. 1A to 1C denote members having the same functions, and the structures and operations thereof are also the same.

In the fluidized bed gasifier shown in FIGS. 2A to 2C, the outer wall of the fluidized bed unit 1 is formed in a rectangular shape. The upper surface of the fluidizing gas dispersing device 6 on a rectangle arranged inside the fluidized bed unit 1 is formed in a mountain shape. In the present embodiment, two symmetrical internal swirling flows 12 are formed between the central portion and the left and right peripheral portions. Inside the fluidized bed unit 1 and above the periphery of the fluidized gas dispersing device 6, there is provided an outlet 16 for the fluidized medium facing outward. Have been. A gap 20 between the fluidizing gas dispersion device 6 and the inner wall of the fluidized bed unit 1 is formed below the outlet 16, and the gap 20 functions as a discharge shoot for the fluid medium. However, this gap 20 is composed of two shoots 20a and 20b as shown in FIG. 2B. Below each shoot 20a.20b, three gas blowing nozzles 13 are provided, respectively.

Other configurations of this embodiment are the same as those shown in FIGS. 1A to 1C. The operation and effect of this embodiment are the same as those of the embodiment shown in FIGS. 1A to 1C.

FIG. 3 is an overall configuration diagram showing one example of components around a gasification furnace when the fluidized-bed gasification furnace according to the present invention is used under pressure. A lock hopper 102 for pressure sealing is connected to the lower part of the gas discharge furnace unit at the lower part of the gasifier 101 having the structure shown in FIGS. 1A to 1C and FIGS. 2A to 2C. A vibrating sieve 103 is provided downstream of the rock hohno 102. The non-combustible material 6 1 and the fluid medium 60 are sieved by the vibrating sieve 103. The non-combustible material 61 is discharged out of the system, and the fluid medium 60 is returned to the furnace. The fluid medium 60 sieved by the vibrating sieve 103 is conveyed by the fluid medium conveyer 104, and passes through the fluid medium supply lock hopper 105 to supply the fluid medium conveyer 10. At 6 it is returned into the gasifier 101. When used in such a device configuration, up to the lock hopper 102 is pressurized and dew condensation easily occurs. Therefore, it is desirable to take dew condensation prevention measures such as heat retention and steam tracing.

FIG. 4 is an overall configuration diagram showing another example of components around the gasification furnace when the fluidized-bed gasification furnace according to the present invention is used under pressure. The fluid medium conveyed by the fluid medium conveyer 104 as in FIG. 3 is once received by the fluid medium hobber 107 and then discharged by the medium quantitative dispenser 108. By adjusting the quantity and switching the switching shoot 109, not only the fluid medium supply lock hopper 105 but also the fuel supply lock hopper 110 and the fuel conveyor 50 together with the fuel 50 are supplied. It is also possible to supply into the furnace at 11.

FIG. 5 is an overall configuration diagram showing a device configuration around a gasification furnace when the present invention is used at normal pressure. The mixture of the incombustible material and the fluid medium discharged from the gasification furnace 101 is conveyed by the conveyer 104 and sieved by the vibrating sieve 103 into the incombustible material 61 and the fluid medium 60. Thereafter, the fluidized medium 60 is supplied to the gasifier 101 by the fluidized medium supply conveyer 106. If there are many non-combustible materials with a small particle size, such as forming a fluid medium in the fuel, the flow path is switched by the switching shot 109 and the excess fluid medium is supplied to the fluid medium hopper 107 side. And discharged to a fluid medium supply conveyor 106 by a fixed-rate dispenser 108 as needed, and put into the furnace.

In the case where there is no sealing mechanism at the fluidized medium outlet as in the system shown in Fig. 5, it is particularly important to pay attention to the fact that the steam input from the bottom of the gasifier Therefore, there is a possibility of flowing to the conveyor 104 side. When such a flow occurs, steam condenses in the conveyor, causing the flowing medium to become moist and impairing the handlability, and causing the limestone and gypsum fines contained in the flowing medium to adhere. In addition to this, the steam does not flow toward the fluidized bed, and the purging function that should be performed is lost, which may cause troubles such as tar and char in the fluid medium discharge section.

Therefore, it is necessary to take measures to ensure that the steam introduced from the bottom of the gasifier 101 flows toward the fluidized bed. One of the methods is to use a conveyor type of conveyor 104, which is filled with a fluid medium. Force S, which is a type of conveyor, this type of conveyor has the problem that the required power is large because the internal fluid medium must be constantly stirred. Another method is to provide a sealing damper between the outlet of the fluidized medium discharge conveyor below the gasification furnace 101 and the transfer conveyor 104. This method requires a function to maintain the seal while discharging the fluid medium, and it is desirable to use a double damper method.However, even a single damper linked to the operation and stoppage of the fluid medium discharge conveyer is desirable. The effect can be expected.

According to the present invention, the following effects can be obtained.

(1) The direction of withdrawal of incombustibles is radially outward or outward when viewed from the fluidized-bed furnace, so that incombustibles are not entangled or bridged, and discharge of incombustibles is easy.

(2) Steam or gas containing no CO ₂ or oxygen is blown from a nozzle provided at the lower part of each shot, and the fluid medium is vigorously fluidized, so that incombustibles can be fueled. This can eliminate blockage troubles in parts.

(3) By injecting steam or inert gas (consisting of CO ₂ or gas containing no oxygen) from the nozzles provided at the bottom of each shoot and at the bottom of the media discharge unit, incombustible substances and The sensible heat of the fluidized medium can be recovered by direct heat exchange with the steam and reduced in the furnace.

(4) Simultaneously, the shoot purge function using steam or inert gas can prevent vaporized tar from entering the shot section, and prevent various problems caused by tar after cooling the fluid medium.

(5) In addition, even if fuel tends to accumulate as a fuel and a large amount of fuel is contained in the formation, the effect of steam or inert gas may cause a short-circuit. Since there is no ingress of oxygen into the part, it is possible to prevent a cleaning problem due to char combustion in the shoot.

(6) At the same time, because the generated gas can be prevented from entering below the shoot, even if the fuel is gasified, such as hydrogen chloride, which produces a highly corrosive gas when dew forms, such as hydrogen chloride. No need to worry about corrosion.

(7) Furthermore, since incombustibles and fluid medium to be discharged outside the furnace can be cooled by steam or inert gas, the medium discharge device does not need to use high-grade materials for heat and corrosion resistance, and can be inexpensive.

(8) Further, even when using under pressure, the temperature of the pressure seal portion downstream of the medium discharge device can be lowered, so that pressure seal with a simple device such as a mouth hopper can be performed.

(9) Even if a large-sized lump is generated due to cleaning power trouble, etc., the large-sized lump is destroyed and crushed to an appropriate size by the forced discharge function of the medium discharge device. As a result, clogging trouble does not occur in the fluid medium discharge system. Industrial applicability

INDUSTRIAL APPLICATION This invention is used suitably for the apparatus which produces | generates gas from fuels, such as waste and coal, using a fluidized bed.

Claims

The scope of the claims

1. A fluidized-bed gasification furnace using a fluidized-bed reactor, which has an outlet for a fluidized medium near a floor of a fluidized bed, and the outlet is a downwardly-discharged fluidized-medium shut-off unit. A fluidized-bed gasification furnace, characterized in that the gasification furnace is connected to a gas blower and has a gas blowing device below the shot.

2. The fluidized bed gasifier ₍₂ ) according to claim 1, further comprising a device for mechanically extracting the fluidized medium near the lowermost portion of the fluidized medium discharge shoot.

3. The fluidized-bed gasification furnace according to claim 1, wherein the fluidized medium discharge shoot has a gas blowing device at a lowermost portion.

4. The fluidized bed gasification furnace according to claim 1, wherein the gas blowing device uses a gas containing no steam, carbon dioxide or oxygen as the gas to be blown.

5. The fluidized-bed gasifier according to claim 2, 3, or 4, wherein the fluid medium extracting device uses a screw conveyor.

6. The fluidized bed reactor is divided into units according to functions, and is configured to easily cope with fuels having different properties by changing the combination of the units. The fluidized bed gasifier according to any one of claims 1 to 5.