CN1295661A

CN1295661A - Fluidized bed gasification furnace

Info

Publication number: CN1295661A
Application number: CN 99804459
Authority: CN
Inventors: 三好敬久; 丰田诚一郎; 福冈大作; 今泉隆司; 千叶信一郎
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 1998-02-27
Filing date: 1999-02-26
Publication date: 2001-05-16
Anticipated expiration: 2019-02-26
Also published as: EP1058051A4; EP1058051A1; CN1239841C; DE69926217D1; AU2641999A; DE69926217T2; EP1058051B1; WO1999043985A1

Abstract

The present invention relates to a fluidized-bed gasification furnace which can rapidly discharge incombustibles contained in a fuel, together with a fluidized medium. The fluidized-bed gasification furnace utilizes a fluidized-bed reactor and comprises a discharge port (16) provided in the vicinity of the floor in a fluidized bed for discharging a fluidized medium and connected to a fluidized medium discharge chutes (20a to 20d) extending downwardly, and a gas blow device (13) provided below the chutes.

Description

Fluidized bed gasification furnace

Technical Field

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

The fluidized bed (layer) is formed by supplying a gas from the lower surface of the particle-packed bed and fluidizing the fluidized medium. The particle-filled layer is filled with particles of a fluid medium such as silica sand or iron oxide of several tens of micrometers to several millimeters. The fluidized bed reactor is a device for rapidly, stably and uniformly performing a chemical reaction by utilizing the fluidity and uniformity of the fluidized bed (layer), the size of heat capacity, the size of surface area, and the like. The catalyst is used for a contact decomposing furnace for petroleum refining, a combustion furnace and an incinerator for solid fuels such as coal and the like, and has good effect.

Background

The fluidized bed gasification furnace has advantages that the fluidized bed gasification furnace has good mixing properties and heat transfer properties due to the presence of the fluidized medium, and the restriction on the size and properties of the fuel that can be charged is small compared to the entrained flow reactor. However, the operation temperature of the fluidized bed reactor has to be lower than that of the entrained flow reactor in order to prevent the ash in the fluidized bed reactor and the fuel from being fused and adhered to each other at high temperature to obstruct the flow. The temperature range is about 900 ℃ or lower when petroleum is used as fuel, and is usually about 600 to 800 ℃ depending on the properties of the waste when the waste is used as fuel, and is further reduced when alkali metals are contained in the waste.

There is a problem that tar is generated when wastes or petroleum are thermally decomposed and gasified at a relatively low temperature. In general, tar is gasified in a temperature range of 600 ℃, but when the temperature is lowered to 200 ℃ or lower, the tar is liquefied, and the tackiness thereof may cause various troubles in handling of particles.

The fluidized-bed gasification furnace is characterized in that a large amount of char is retained in the furnace, and therefore, when incombustibles are taken out from the inside of the furnace, the char at high temperature is burned by contacting with air, and the temperature is increased, and slag is sometimes generated.

Although the fluidized bed gasification reactor has the advantage of being less limited in the size and properties of the fuel that can be charged, if a fuel containing incombustibles such as petroleum and waste is charged, the incombustibles remaining in the reactor become large if the particle size is large, and it is necessary to discharge the fuel from the reactor by some means. However, it is very difficult to take out the fluidized medium having a high temperature of 500 to 600 ℃ from the fluidized bed even in an apparatus for reaction under normal pressure because of the high temperature, and in particular, it is almost impossible to use a gasification furnace operated under pressure. Even if the fluid medium can be taken out from the fluidized bed, the heat loss due to the taking-out of the high-temperature fluid medium is large, the heat utilization efficiency is low, and a large amount of char mixed in the fluid medium is burned by contacting with air at the time of taking-out, resulting in an unexpected trouble.

When the fluidized bed reactor is cooled, the gasified tar is liquefied, which may cause various troubles, and therefore, the fuel must be finely pulverized and then charged so as not to take out the incombustibles, and the above-mentioned advantages of the fluidized bed reactor cannot be exhibited.

Summary of the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fluidized bed gasification furnace which can exhibit the advantages of a fluidized bed reaction apparatus "the restriction on the size and properties of a fuel to be charged is small", can be safely operated not only under normal pressure but also under high pressure, and has excellent operability.

In order to achieve the above object, the fluidized bed gasification furnace of the present invention employs a fluidized bed reaction apparatus, wherein a discharge chute for a fluidized medium is provided in the vicinity of the bed surface of the reaction apparatus, and a gas blowing device is provided below the chute.

In the fluidized-bed gasification furnace, a device for mechanically taking out the fluidized medium is provided in the vicinity of the lowermost portion of the fluidized medium discharge chute, and the device may be a screw conveyor.

The flowing medium discharge chute may be provided with a gas blowing device at the lowermost portion thereof. The gas blown out by these gas blowing devices may be steam, carbon dioxide, or a gas containing no oxygen.

The fluidized bed reactor used in the present invention is divided into individual units according to functions, and the combination of the units is changed to easily cope with fuels having different properties.

Brief description of the drawings

Fig. 1A, 1B, and 1C are sectional views showing the structure of a cylindrical fluidized-bed gasification furnace, which shows an example of the fluidized-bed gasification furnace of the present invention. FIG. 1A is a longitudinal sectional view of a fluidized-bed gasification furnace, 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.

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

FIG. 3 is an overall configuration diagram showing an example of a configuration device around a gasification furnace according to the present invention.

FIG. 4 is a view showing the overall configuration of another example of the gasification furnace peripheral constituting equipment of the present invention.

FIG. 5 is an overall configuration diagram showing another example of the gasification furnace peripheral constituting equipment 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

The present invention will be described in detail below with reference to the accompanying drawings.

The fluidized bed gasification furnace using a cylindrical fluidized bed reactor shown in FIGS. 1A to 1C is composed of a fluidized bed unit 1, a hopper unit 2 under the furnace, a medium discharger unit 3, a melting chamber unit 4, and a guide unit 5. In the present invention, the fluidized bed reactor is composed of a fluidized bed unit 1, a hopper unit 2 under the furnace, and a medium discharge unit 3. Adjacent units are connected by flanges. Inside the fluidized bed unit 1, a fluidizing gas dispersing means 6 having a conical upper surface is provided, and a plurality of fluidizing gas dispersing nozzles 7 are provided above the fluidizing gas dispersing means 6.

The fluidized bed unit 1 and the unit below the fluidized bed unit 1 are filled with a fluidizing medium 11, and the fluidizing medium above the fluidizing gas dispersing means 6 is fluidized by fluidizing gas blown from the fluidizing gas dispersing nozzles 7 to form a fluidized bed 8. An air header 9 divided into at least 2 parts is built in the fluidizing gas dispersing means 6, and the fluidizing gas velocity blown out from the fluidizing gas dispersing nozzles 7 is made higher in the peripheral part than in the central part, and by making the velocities different, the internal swirling flow 12 of the fluidizing medium is formed in the fluidized bed. The temperature of the fluidizing medium in the fluidizing gas dispersing means 6 is maintained at 400 to 1000 c, preferably 500 to 800 c.

An outward flow medium discharge port 16 is provided in the fluidized bed unit 1 above the periphery of the fluidizing gas dispersing means 6. Below the discharge port 16, a gap 20 is formed between the fluidizing gas dispersing means 6 and the inner wall of the fluidized bed unit 1. The gap 20 functions as a discharge chute for the fluidized medium, and the gap 20 is divided into 4 chutes 20a to 20d by the support member 10 that fixes the fluidizing gas dispersing means 6 and the inner wall of the fluidized bed unit 1. A pipe for supplying fluidizing gas from the outside of the fluidized bed unit 1 to the air manifold 9 may be provided inside the support 10.

In order to prevent incombustibles from accumulating in the fluidized bed 8, each of the chutes 20a to 20d is preferably connected to the entire side surface of the fluidizing gas dispersing means 6. In this case, the support body 10 inevitably has a peak shape at its upper end, and the peak of the peak shape is an acute angle. In order to incorporate the pipe into the support body 10, the support body 10 must have a certain width, and therefore the support body 10 must have a shape that expands downward, and the circumferential width of each of the chutes 20a to 20d becomes narrower. However, in each of the chutes 20a to 20d, in order to avoid internal clogging by incombustibles, it is necessary to avoid the horizontal cross-sectional area thereof from gradually narrowing downward. Therefore, in the gasification furnace of the present invention, the lower side surface 6a of the fluidizing gas dispersing means 6 is inclined toward the centerline side as it goes downward, and the size in the radial direction of each of the chutes 20a to 20d is increased as it goes downward, thereby preventing the horizontal cross-sectional area from decreasing.

A gas blow-out nozzle 13 is provided vertically below each of the chutes 20a to 20d, and the inside of the chute is cleaned with steam or an inert gas to prevent diffusion of tar or oxygen, activate a flow medium to cause the flow medium to flow, and eliminate clogging of the chute.

A medium discharge device unit 3 is connected to the lower side of the lower hopper unit 2, and the inner surface of the lower hopper unit 2 in the gasification furnace is inclined in conformity with the size of the inlet of the medium discharge device unit 3 and is contracted as a whole. By this contraction, dangerous incombustible such as wire, for example, forming the arch (ブリツヅ) can be discharged, and it may be a straight vertical wall, or it may be eccentric and provided with a vertical portion and an inclined portion.

A medium discharge device 15 is provided below the medium discharge device unit 3. In the present gasification furnace, the medium discharge device 15 is a screw conveyor, but a discharge device capable of discharging in the lateral direction, such as a chain conveyor, may be used depending on the nature of the incombustibles. In the present gasification furnace, the medium discharge device 15 is provided horizontally and horizontally, but may be provided so as to be inclined upward or downward.

A gas blow-out nozzle 14 is provided below the medium discharge device 15 at the lowermost part of the medium discharge device unit 3. In the present gasification furnace, the number of the gas blow-out nozzles 14 is 1, but the number of the nozzles may be increased as necessary in order to allow the gas to enter and exit from the entire diameter of the connection portion between the medium discharger unit 3 and the under-furnace hopper unit 2. Since the incombustibles are concentrated by the air separation effect of the gas blown out from the gas blowout nozzle 14, the amount of the discharged fluid medium is also reduced, and the amount of the entrained heat is also reduced.

Blowing steam or CO from the gas blow-out nozzle 14₂Or oxygen-free gas 30, into which steam and CO are blown₂In the case where the carbon particles are contained in the fluid medium in the chute, the cooling effect can be further improved by the endothermic reaction.

Of course, steam or CO is blown from the gas blow-out nozzle 13₂The same effect can be obtained.

When steam is injected from the

nozzles

13 and 14, the temperature of the injected steam must be at least equal to or lower than the saturation temperature of the operating pressure of the gasification furnace. Similarly, the medium discharge device and the like cannot lower the internal temperature below the dew point, and is subjected to heat preservation or heating treatment to prevent condensation, if necessary.

The gasification furnaces shown in fig. 1A to 1C are unitized with the portions that perform the respective functions, but may be integrally formed as a single unit. In particular, in the case of a large-sized furnace, since each part is relatively large, a sufficient maintenance space can be obtained, and there is no need to divide the furnace into units for maintenance, the furnace can be integrally manufactured. However, when used under pressure, the volume is reduced and the internal maintenance is difficult, so that the unit division type as shown in fig. 1A to 1C is effective.

The cell-divided structure has an advantage that the structure can be easily changed according to the properties of the fuel. For example, in order to increase the height of the layer, a straight pipe portion 1a may be added between the guide unit 5 and the fluidized bed unit 1 as shown in fig. 6, in order to increase the fuel which is not easily vaporized and requires a long residence time in the fluidized layer. For a fuel having a small specific gravity, a low in-layer retention rate, and a long residence time in the melting chamber, a melting chamber unit 4 shown in fig. 7 is used, and the melting chamber unit 4 is formed in a shape bulging outward from a slightly upper portion of the flange portion, and has a large inner volume. Thus, as shown in fig. 6 and 7, the fuel can be easily adapted to various fuels without modifying the whole, as long as the necessary portions are modified.

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

In the fluidized-bed gasification furnace shown in fig. 2A to 2C, the outer wall of the fluidized-bed unit 1 is formed in a rectangular shape. The rectangular fluidizing gas dispersing means 6 disposed inside the fluidized bed unit 1 has a peak shape formed on the upper surface thereof. In this embodiment, 2 internal swirling flows 12 are formed between the central portion and the left and right peripheral portions in bilateral symmetry. An outward flow medium discharge port 16 is provided in the fluidized bed unit 1 above the periphery of the fluidizing gas dispersing means 6. Below the discharge port 16, a gap 20 is formed between the fluidizing gas dispersing means 6 and the inner wall of the fluidized bed unit 1, and the gap 20 functions as a discharge chute for the fluidizing medium, and as shown in fig. 2B, the gap 20 is composed of 2 chutes 20a and 20B. Vertically below each of the

chutes

20a and 20b, 3 gas blow-out nozzles 13 are provided.

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

FIG. 3 is a view showing an overall configuration of an example of a surrounding constituent device of a gasification furnace in the case where the fluidized-bed gasification furnace of the present invention is used under pressure. A closed hopper 102 for pressure sealing is connected to a downstream of a medium discharger unit at the lower part of a gasification furnace 101 having the structure shown in fig. 1A to 1C and fig. 2A to 2C, and a vibrating screen 103 is provided downstream of the closed hopper 102. The vibrating screen 103 screens the incombustibles 61 and the flowing medium 60, and the incombustibles 61 are discharged out of the system, and the flowing medium 60 is returned to the furnace again. The fluidized medium 60 after being sifted by the vibrating screen 103 is carried by the fluidized medium conveyer 104, and is returned to the gasification furnace 101 by the fluidized medium supply conveyer 106 via the closed hopper 105 for supplying a fluidized medium. When used in such an equipment structure, the funnel 102 is pressurized before being closed, and condensation is likely to occur, so that it is preferable to take measures against condensation such as heat retention and vapor tracking.

FIG. 4 is a view showing the overall structure of another example of the equipment constituting the periphery of the gasification furnace in the case where the fluidized bed gas furnace of the present invention is used under pressure. Similarly to fig. 3, the flowing medium carried by the flowing medium conveyor 104 is received by the flowing medium hopper 107, the flow rate is adjusted by the medium quantitative discharger 108, and the flowing medium can be supplied into the furnace from the supply conveyor 111 together with the fuel 50 not only from the flowing medium supply closed hopper 105 but also from the fuel supply closed hopper 110 side by switching the chute 109.

FIG. 5 is an overall structural view showing the structure of the equipment around the gasification furnace when the present invention is used under normal pressure. The mixture of incombustibles and the fluid medium discharged from the gasification furnace 101 is carried by the conveyor belt 104 and is further screened into incombustibles 61 and the fluid medium 60 by the vibrating screen 103. Then, the fluidized medium 60 is supplied to the gasification furnace 101 by the fluidized medium supply conveyor 106. When there is a large amount of incombustibles having a small particle diameter, such as a flow medium, in the fuel, the flow path is switched by the switching chute 109, and the remaining flow medium is stored in the flow medium hopper 107 side, discharged to the flow medium supply conveyor 106 by the constant-weight discharger 108 as necessary, and charged into the furnace.

When there is no sealing mechanism in the fluidized medium extraction portion as in the system shown in fig. 5, it should be particularly noted that the steam introduced from the lowermost portion of the gasification furnace 101 may flow not to the fluidized bed portion but to the conveyor 104 side. When such a flow occurs, the vapor condenses in the conveyor belt, and the flowing medium is humidified, so that the operability is deteriorated, or the limestone or gypsum fine powder contained in the flowing medium is fixed, and the vapor does not flow to the fluidized bed portion, so that the originally possessed cleaning function is lost, and the trouble is caused in the tar or char in the flowing medium take-out chute portion.

Therefore, the steam introduced from the lowermost portion of the gasification furnace 101 must be made to flow into the fluidized bed. One method is to make the conveyor belt 104 in a form that the flowing medium can fill the internal conveyor belt, but this form of conveyor belt must often mix the flowing medium inside, and therefore requires a large power. In another method, a baffle plate for sealing is provided between the outlet of the fluidized medium discharge conveyor at the lower part of the gasification furnace 101 and the conveyor 104. In this method, although the double baffle method is preferable to maintain the seal while discharging the fluid medium, a single baffle interlocked with the operation and stop of the fluid medium discharge conveyor can also obtain a certain degree of effect.

The present invention has the following effects.

(1) The direction of taking out the incombustibles is outward or outward in a radial shape as viewed from the fluidized bed furnace side, so that the incombustibles do not get entangled or overlap, and the incombustibles are easily discharged.

(2) Blowing steam or CO from nozzles arranged at the lower part of each chute₂Or a gas containing no oxygen, and the nonflammable material is blown by activating the fluidizing medium, thereby eliminating the clogging of the chute.

(3) Steam or inert gas (CO) is blown from nozzles provided at the lower part of each chute and the lowermost part of themedium discharge device unit₂Or oxygen-free gas) to recover the sensible heat of the incombustibles and the fluidizing agent by directly exchanging heat with the steam, and to reduce the sensible heat to the furnace.

(4) At the same time, the chute is cleaned by steam or inactive gas, which can prevent gasified tar from entering the chute and prevent various troubles caused by the cooled tar of the flowing medium.

(5) Even if char is easily accumulated in the fuel layer and a large amount of char is contained in the layer, oxygen does not enter the chute portion by the action of steam or an inert gas, so that slag caused by burning of char in the chute can be prevented.

(6) Since the generated gas can be prevented from entering the lower part of the chute at the same time, even when a fuel such as hydrogen chloride, which generates a highly corrosive gas upon condensation, is vaporized, there is no fear of corrosion.

(7) Since the incombustible and the fluid medium discharged to the outside of the furnace can be cooled by the steam or the inert gas, the medium discharge device does not need to use a high-grade material having heat resistance and corrosion resistance, and the price can be reduced.

(8) Even when used under pressure, the temperature of the pressure seal portion downstream of the medium discharge device is lowered, and therefore, pressure sealing can be performed by a simple device such as a closed funnel.

(9) Even if large-sized lumps are generated due to slag or the like, the large-sized lumps can be broken and crushed into appropriate sizes by the forced discharge function of the medium discharge device, and therefore, no clogging occurs in the flowing medium discharge system.

Industrial applicability

The present invention is applicable to an apparatus for generating gas from fuel such as waste or coal by using a fluidized bed.

Claims

1. The fluidized bed gasification furnace adopts a fluidized bed reaction device, and is characterized in that a discharge port for a fluid medium is provided near the bed surface of the fluidized bed, and the discharge port is connected with a discharge chute for the fluid medium facing downwards, and at the bottom of the chute There is a gas blowing device below.

2. The fluidized bed gasification furnace according to claim 1, wherein a device for mechanically taking out the fluidized medium is provided near the lowermost portion of the fluidized medium discharge chute.

3. The fluidized bed gasification furnace according to claim 1 or 2, wherein said fluid medium discharge chute is provided with a gas blowing device at the lowermost part.

4. The fluidized bed gasification furnace according to claim 1, 2 or 3, characterized in that the gas blowing device uses water vapor or carbon dioxide or oxygen-free gas as the blowing gas.

5. The fluidized bed gasification furnace according to claim 2, 3 or 4, characterized in that the above-mentioned gas fluid medium taking-out device is a screw conveyor.

6. The fluidized bed gasifier according to any one of claims 1 to 5, wherein the fluidized bed reaction device is divided into units according to functions, and by changing the combination of each unit, it can easily correspond to different properties. fuel.