EP3540031B1

EP3540031B1 - Method and apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed

Info

Publication number: EP3540031B1
Application number: EP17893195.2A
Authority: EP
Inventors: Lianhua ZHANG; Baijin CHEN; Ji Wang; Hui Zhang; Yunlong QIU
Original assignee: Zhongke Juxin Clean Energy and Hot Forging Equipment Research and Development Co Ltd
Current assignee: Zhongke Juxin Clean Energy and Hot Forging Equipment Research and Development Co Ltd
Priority date: 2017-01-23
Filing date: 2017-06-13
Publication date: 2021-03-03
Anticipated expiration: 2037-06-13
Also published as: JP2019515996A; US20190367826A1; EP3540031A4; CN106635179B; JP6716179B2; WO2018133303A1; EP3540031A1; CN106635179A

Description

Technical Field

The present invention relates to a composite gasification apparatus for coal gasification, and specifically, to a gasification furnace for sequentially performing fluidization, pyrolysis, and gasification by a circulating fluidized bed and a pyrolysis bed. The composite gasification apparatus is used for gasification of raw coal, and belongs to the field of coal gasification equipment technologies.

BACKGROUND

With the rapid development of industrial economies, coal combustion has become an indispensable path for obtaining thermal energy in industrial production processes. However, direct coal combustion pollutes the environment heavily. Therefore, Chinese government has issued a large number of documents on prohibiting direct coal burning for obtaining thermal energy in recent years. Instead, raw coal is converted to clean and pollution-free coal gas for combustion to obtain thermal energy. Therefore, various gasification furnaces, such as a fixed bed gasification furnace or a circulating fluidized bed gasification furnace, for converting the raw coal to the coal gas have been designed to reduce pollution to the environment caused by combustion to some extent. However, when going deep into various forms of existing gasifiers, it has been found that each gasifier has its advantages and disadvantages. For example, the fixed bed gasifier has a high coal conversion rate and a high thermal efficiency, but the generated coal gas contains a large number of contaminants such as tar. The circulating fluidized bed gasifier can produce clean coal gas that does not contain contaminants such as tar, but it has low thermal efficiency of raw coal, coal slag contains a large amount of semi-coke, and coke-containing coal slag needs to be transported to a burning environment with low requirements for re-burning such as a raw material burnt in a thermal power plant. On one hand, the coal utilization rate is decreased, and on the other hand, multiple items of costs such as transportation manpower are increased. Therefore, there is a need for a coal gasification device, which can ensure the high efficiency of converting raw coal into gas and obtain clean gas at the same time.
US 4,552,078 discloses an apparatus and method for recycling fly ash to a fluidized bed coal gasifier.
US 4,684,375 relates to a method and an installation for processing materials in a circulating fluidized bed, separating the solids from the produced gas and feeding them to a processing compartment before recycling them to the reactor.

SUMMARY

An objective of the present invention is to provide a method for implementing gasification by combining circulating fluidized bed and pyrolysis bed. In the method, combustion and gasification are performed by combining a circulating fluidized bed gasification furnace and a pyrolysis bed gasification furnace, thereby improving conversion efficiency of raw coal, and eliminating primary pollutants in coal gas.
The objective of the present invention is further to provide an apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed, which performs fluidized gasification and pyrolysis gasification on raw coal subsequently, and is a device configured to produce clean coal gas with the high conversion efficiency.
To achieve the foregoing objective, according to one aspect of the present invention, the present invention provides an apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed as claimed in claim 1.
In a further embodiment, the oblique guide plate is obliquely disposed in the deposition chamber.
In a further embodiment, the gas distribution body is cone-shaped.
In a further embodiment, a top portion of the central cylinder of the cyclone separator is in communication with the top portion of the deposition chamber by using the second coal gas pipe.
According to anther aspect of the present invention, the present invention provides a method for implementing gasification by combining circulating fluidized bed and pyrolysis bed. The method includes: combusting, fluidizing, and gasifying raw coal in an environment with a temperature of 900°C to 1200°C in a circulating fluidized bed gasification furnace preliminarily to generate coal gas, carbon-containing fly ash and semicoke, and feeding the carbon-containing fly ash and the semicoke into a cyclone separator together with the coal gas; introducing the coal gas, the carbon-containing fly ash, and the semicoke in the circulating fluidized bed gasification furnace into the cyclone separator from an upper portion of the cyclone separator, introducing separated semicoke into a pyrolysis bed gasification furnace, introducing a gasification agent into a bottom portion of the pyrolysis bed gasification furnace, and combusting the separated semicoke in the pyrolysis bed gasification furnace for further pyrolysis and gasification; introducing coal gas generated in the pyrolysis bed gasification furnace, the coal gas and the carbon-containing fly ash generated in the circulating fluidized bed gasification furnace into a deposition chamber through a central cylinder of the cyclone separator, and discharging coal slag from a slag pan at the bottom portion of the pyrolysis bed gasification furnace; and, introducing the carbon-containing fly ash deposited in the deposition chamber into a first mixture gas distribution chamber on a bottom portion of the circulating fluidized bed gasification furnace by using a conveyor and a fly ash pipe, and then introducing the carbon-containing fly ash heated along with a gasification agent into the circulating fluidized bed gasification furnace for circulating gasification and combustion.
In a further embodiment, the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is mixed gases of air and vapor, and the semicoke are combusted and pyrolyzed in the pyrolysis bed gasification furnace.
In a further embodiment, the gasification agent introduced into the bottom portion of the circulating fluidized bed gasification furnace is mixed gases of air, vapor and oxygen, and the raw coal are combusted and pyrolyzed in the circulating fluidized bed gasification furnace.
In a further embodiment, the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is mixed gases of air, vapor and oxygen, and the semicoke are combusted and pyrolyzed in the pyrolysis bed gasification furnace.
According to an unclaimed embodiment not according to the invention, there is provided an apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed. The apparatus includes: a circulating fluidized bed gasification furnace, comprising a coal conveying pipe configured for conveying raw coal to the circulating fluidized bed gasification furnace, a gasification agent being introduced into a bottom portion of the circulating fluidized bed gasification furnace, and the raw coal being fluidizedly combusted and pyrolysed in the circulating fluidized bed gasification furnace to generate coal gas, carbon-containing fly ash, and semicoke; and a pyrolysis bed gasification furnace having an upper portion being in communication with an upper portion of the circulating fluidized bed gasification furnace via a coal gas pipe and a coal gas outlet disposed on the upper portion thereof. The coal gas, the carbon-containing fly ash, and the semicoke that are generated in the circulating fluidized bed gasification furnace enter the pyrolysis bed gasification furnace by using the coal gas pipe, the semicoke drops onto a bottom portion of the pyrolysis bed gasification furnace, a gasification agent is introduced into the bottom portion of the pyrolysis bed gasification furnace, the semicoke are combusted in the pyrolysis bed gasification furnace to be further pyrolysed and gasified to generate coal gas, and coal slag are discharged from a slag pan at the bottom portion of the pyrolysis bed gasification furnace.
In a further unclaimed embodiment not according to the invention, a gasification furnace chamber is disposed on the upper portion of the circulating fluidized bed gasification furnace, a gas distributor is disposed in a middle portion of the circulating fluidized bed gasification furnace, a first mixture gas distribution chamber is disposed on a lower portion of the circulating fluidized bed gasification furnace, and the gasification agent is introduced into the first mixture gas distribution chamber; and a bottom portion of a furnace body of the pyrolysis bed gasification furnace is floatingly disposed on the slag pan, a watertight seal is disposed between the slag pan and the bottom portion of the furnace body of the pyrolysis bed gasification furnace, a gas distribution body is disposed on the bottom portion of the furnace body of the pyrolysis bed gasification furnace and located on the slag pan, a second mixture gas distribution chamber is disposed between the slag pan and a lower portion of the gas distribution body, and the gasification agent is introduced into the second mixture gas distribution chamber.
In a further unclaimed embodiment not according to the invention, the apparatus further includes: a deposition chamber, a conveyor, a high-temperature air pipe, a vapor pipe, an oxygen pipe, and a fly ash pipe, where a top portion of the pyrolysis bed gasification furnace is in communication with a top portion of the deposition chamber by using a coal gas pipe; an oblique guide plate is disposed on an upper portion of the deposition chamber, and the conveyor is disposed on a bottom portion of the deposition chamber; and the conveyor is connected to the fly ash pipe; and the high-temperature air pipe, the vapor pipe, the oxygen pipe, and the fly ash pipe are in communication with the first mixture gas distribution chamber, and the high-temperature air pipe, the vapor pipe, and the oxygen pipe are in communication with the second mixture gas distribution chamber.
Because the circulating fluidized bed gasification furnace has advantage of no pollutants, such as tar, during gasification, and the fixed gasification bed has advantage of high raw coal gasification rate, the circulating fluidized bed gasification furnace and the pyrolysis bed gasification furnace are combined into one coal gasification device in the present invention, so that the combined coal gasification device not only does not produce pollutants such as tar, but also achieves high conversion rate of raw coal to gas. The present invention achieves a high raw coal gasification rate, produces no pollutants, such as tar, during gasification, is applicable to equipment with large, medium, and small gasification capacities, and has a large adjustment range of gas yield per unit time.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings are schematic structural diagrams of embodiments of the present invention.

FIG. 1 is a schematic structural diagram of an apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed according to a first embodiment of the present invention; and
FIG. 2 is a schematic structural diagram of the apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed according to a second embodiment of the present invention.

In Figs. 1 and 2, 1 is a coal bunker, 2 is a circulating fluidized bed gasification furnace, 3 is a cyclone separator, 4 is a deposition chamber, 5 is a conveyor, 6 is a high-temperature air pipe, 7 is a vapor pipe, 8 is an oxygen pipe, 9 is a fly ash pipe, 201 is a gas distributor, 202 is a first mixture gas distribution chamber, 301 is a cone-shaped gas distribution body, 302 is a slag pan, 303 is a second mixture gas distribution chamber, 401 is an oblique guide plate, A is raw coal, B is semicoke, C is carbon-containing fly ash, and D is coal slag.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To make the foregoing objectives, features, and advantages of the present invention more comprehensible, the present invention is described in further detail with reference to the accompanying drawings and specific implementations.
FIG. 1 is a schematic structural diagram of an apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed according to a first embodiment of the present invention. As shown in FIG. 1, the apparatus includes a raw coal bunker 1, a circulating fluidized bed gasification furnace 2, a cyclone separator 3, a deposition chamber 4, a conveyor 5, a high-temperature air pipe 6, a vapor pipe 7, an oxygen pipe 8, a fly ash pipe 9, a slag pan 302 and a cone-shaped gas distribution body 301. The raw coal bunker 1 is in communication with the circulating fluidized bed gasification furnace 2 by using a coal conveying pipe. An upper portion of the circulating fluidized bed gasification furnace 2 is in communication with an upper portion of the cyclone separator 3 via a first coal gas pipe. A top portion of the cyclone separator 3 is in communication with a top portion of the deposition chamber 4 via a second coal gas pipe. In this embodiment shown in FIG. 1, a top portion of a central cylinder of the cyclone separator 3 is in communication with the top portion of the deposition chamber 4 via the second coal gas pipe. Raw coal A is disposed in the raw coal bunker 1. A gasification furnace chamber is disposed on the upper portion of the circulating fluidized bed gasification furnace 2. A gas distributor 201 is disposed on a middle portion of the circulating fluidized bed gasification furnace 2. A first mixture gas distribution chamber 202 is disposed on a lower portion of the circulating fluidized bed gasification furnace 2. The central cylinder is disposed on the upper portion of the cyclone separator 3. A bottom portion of the cyclone separator 3 is floatingly disposed on the slag pan 302. The cone-shaped gas distribution body 301 is disposed on the bottom portion of the cyclone separator and located on the slag pan 302. A watertight seal is disposed between the slag pan 302 and the bottom portion of the cyclone separator 3. A second mixture gas distribution chamber 303 is disposed between the slag pan 302 and a lower portion of the cone-shaped gas distribution body 301. A lower portion of an inner cavity of the cyclone separator 3, the cone-shaped gas distribution body 301 and the second mixture gas distribution chamber 303 below the cone-shaped gas distribution body 301 together constitute a pyrolysis bed gasification furnace. The cone-shaped gas distribution body 301 may be of other shapes, such as a hemisphere. An oblique guide plate 401 is disposed on an upper portion of the deposition chamber 4, and the conveyor 5 is disposed on a bottom portion of the deposition chamber 4. The conveyor 5 is connected to the fly ash pipe 9. The high-temperature air pipe 6, the vapor pipe 7, the oxygen pipe 8 and the fly ash pipe 9 are in communication with the first mixture gas distribution chamber 202 disposed on the lower portion of the circulating fluidized bed gasification furnace 2. The high-temperature air pipe 6, the vapor pipe 7 and the oxygen pipe 8 are in communication with the second mixture gas distribution chamber 303 disposed on the lower portion of the con-shaped gas distribution body 301.
When the apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed is operating, the raw coal A enters the circulating fluidized bed gasification furnace 2 to be preliminarily combusted, pyrolysed, and gasified in an environment with a temperature of 900°C to 1200°C, to generate coal gas, carbon-containing fly ash C, and semicoke B. The carbon-containing fly ash C and the semicoke B are fed into the cyclone separator 3 together with the coal gas. A gasification agent is introduced into a bottom portion of the pyrolysis bed gasification furnace. The coal gas, the carbon-containing fly ash C, and the semicoke B enter the cyclone separator 3 from an upper portion of the apparatus, and the semicoke B are further combusted, pyrolysed, and gasified in the pyrolysis bed gasification furnace. Coal gas generated in the pyrolysis bed gasification furnace, and the coal gas and the carbon-containing fly ash C that are generated in the circulating fluidized bed gasification furnace enter the deposition chamber 4 through the central cylinder of the cyclone separator 3, and coal slag are discharged from the slag pan 302 on the bottom portion of the pyrolysis bed gasification furnace. After the coal gas and the carbon-containing fly ash C are deposited in the deposition chamber 4, the carbon-containing fly ash is fed into the first mixture gas distribution chamber 202 on the bottom portion of the circulating fluidized bed gasification furnace 2 by the conveyor 5 and the fly ash pipe 9. The carbon-containing fly ash together with the gasification agent further enters the circulating fluidized bed gasification furnace for circulating combustion, pyrolysis and gasification to supplement heat in the circulating fluidized bed gasification furnace 2. FIG. 2 is a schematic structural diagram of the apparatus for implementing gasification by combining circulating fluidized bed and pyrolysis bed according to an unclaimed embodiment not according to the invention.
As shown in FIG. 2, the apparatus includes a circulating fluidized bed gasification furnace 2 and a pyrolysis bed gasification furnace 11. The circulating fluidized bed gasification furnace 2 includes a coal conveying pipe 101 conveying raw coal to the circulating fluidized bed gasification furnace, and a gasification agent channel 102 introducing a gasification agent to a bottom portion of the circulating fluidized bed gasification furnace. The raw coal is fluidized bed combusted and pyrolysed in the circulating fluidized bed gasification furnace 2 to generate coal gas, carbon-containing fly ash and semicoke. An upper portion of the pyrolysis bed gasification furnace 11 is in communication with an upper portion of the circulating fluidized bed gasification furnace 2 by using a coal gas pipe. The coal gas, the carbon-containing fly ash, and the semicoke that are generated in the circulating fluidized bed gasification furnace 2 enter the pyrolysis bed gasification furnace 11 through the coal gas pipe, and the semicoke drop onto a bottom portion of the pyrolysis bed gasification furnace 11. A gasification agent is introduced into the bottom portion of the pyrolysis bed gasification furnace 11 through a gasification agent channel 111. The semicoke are combusted in the pyrolysis bed gasification furnace 11 to be further pyrolysed and gasified to generate coal gas. A coal gas outlet 112 is disposed on the upper portion of the pyrolysis bed gasification furnace 11, and coal slag are discharged from a slag pan on the bottom portion of the pyrolysis bed gasification furnace 11. Because the circulating fluidized bed gasification furnace has advantage of no pollutants, such as tar, during gasification, and the fixed gasification bed has advantage of high raw coal gasification rate, the circulating fluidized bed gasification furnace and the pyrolysis bed gasification furnace are combined into one coal gasification device in the present invention, so that the combined coal gasification device not only does not produce pollutants such as tar, but also achieves high conversion rate of raw coal to gas. The present invention achieves a high raw coal gasification rate, produces no pollutants, such as tar, during gasification, is applicable to equipment with large, medium, and small gasification capacities, and has a large adjustment range of gas yield per unit time.
In one preferred embodiment, a gasification furnace chamber is disposed on the upper portion of the circulating fluidized bed gasification furnace 2; a gas distributor 201 is disposed on a middle portion of the circulating fluidized bed gasification furnace 2; a first mixture gas distribution chamber 202 is disposed on a lower portion of the circulating fluidized bed gasification furnace 2; the gasification agent is introduced into the first mixture gas distribution chamber 202. A bottom portion of a furnace body 113 of the pyrolysis bed gasification furnace 11 is floatingly disposed on a slag pan 302. A watertight seal is disposed between the slag pan 302 and the bottom portion of the furnace body 113 of the pyrolysis bed gasification furnace. A gas distribution body 301 is disposed on the bottom portion of the furnace body 113 of the pyrolysis bed gasification furnace 111 and located on the slag pan 302. A second mixture gas distribution chamber 303 is disposed between the slag pan 302 and a lower portion of the gas distribution body 301. The gasification agent is introduced into the second mixture gas distribution chamber 303. In one preferred embodiment, the circulating fluidized bed gasification furnace 2 includes an oblique guide plate 114 disposed on the upper portion. The oblique guide plate 114 can guide the coal gas, the carbon-containing fly ash and the semicoke that enter the pyrolysis bed gasification furnace 11 through the coal gas pipe to be downward, so that the semicoke drop onto the bottom portion of the pyrolysis bed gasification furnace 11 more easily.
In one more preferred embodiment, the apparatus further includes: a deposition chamber, a conveyor, a high-temperature air pipe, a vapor pipe, an oxygen pipe, and a fly ash pipe. A top portion of the pyrolysis bed gasification furnace is in communication with a top portion of the deposition chamber by using a coal gas pipe. An oblique guide plate is disposed on an upper portion of the deposition chamber, and the conveyor is disposed on a bottom portion of the deposition chamber. The conveyor is connected to the fly ash pipe. The high-temperature air pipe, the vapor pipe, the oxygen pipe and the fly ash pipe are in communication with the first mixture gas distribution chamber 202. The high-temperature air pipe, the vapor pipe and the oxygen pipe are in communication with the second mixture gas distribution chamber 303.
The foregoing descriptions have fully disclosed the specific implementations of the present invention. It should be noted that any change made to the specific implementations of the present invention by a person skilled in the art does not depart from the scope of the claims of the present invention. Correspondingly, the scope of the claims of the present invention is not limited only to the specific implementations.

Claims

An apparatus for implementing gasification of raw coal (A) by combining a circulating fluidized bed and a pyrolysis bed, comprising: a circulating fluidized bed gasification furnace (2), a cyclone separator (3), a deposition chamber (4), a conveyor (5), a high-temperature air pipe (6), an oxygen pipe (8), a fly ash pipe (9), a slag pan (302), and a pyrolysis bed gasification furnace (301, 303) comprising a gas distribution body (301), and
wherein the raw coal enters the circulating fluidized bed gasification furnace through the coal conveying pipe, an upper portion of the circulating fluidized bed gasification furnace is in communication with an upper portion of the cyclone separator via a first coal gas pipe, and the circulating fluidized bed gasification furnace comprises a gasification furnace chamber disposed on the upper portion thereof, characterized in that
the apparatus also comprises a vapor pipe (7), and a top portion of the cyclone separator is in communication with a top portion of the deposition chamber via a second coal gas pipe;
wherein a gas distributor (201) is disposed in a middle portion of the circulating fluidized bed gasification furnace, and a first mixture gas distribution chamber (202) is disposed on a lower portion thereof; the cyclone separator comprises a central cylinder disposed in a middle of the upper portion thereof, a bottom portion of the cyclone separator is floatingly disposed on the slag pan, a watertight seal is disposed between the slag pan and the bottom portion of the cyclone separator, the gas distribution body is disposed on the bottom portion of the cyclone separator and located on the slag pan, a second mixture gas distribution chamber (303) is disposed between the slag pan and a lower portion of the gas distribution body; a lower portion of an inner cavity of the cyclone separator, the gas distribution body and the second mixture gas distribution chamber below the gas distribution body together constitute the pyrolysis bed gasification furnace; an oblique guide plate (401) is disposed on an upper portion of the deposition chamber, and the conveyor is disposed on a bottom portion of the deposition chamber and is connected to the fly ash pipe; and
wherein the high-temperature air pipe, the vapor pipe, the oxygen pipe and the fly ash pipe are in communication with the first mixture gas distribution chamber on the lower portion of the circulating fluidized bed gasification furnace, and the high-temperature air pipe, the vapor pipe, and the oxygen pipe are in communication with the second mixture gas distribution chamber disposed on the lower portion of the gas distribution body.
The apparatus for implementing gasification of raw coal (A) by combining a circulating fluidized bed and a pyrolysis bed according to claim 1, wherein the oblique guide plate is obliquely disposed in the deposition chamber.
The apparatus for implementing gasification of raw coal (A) by combining a circulating fluidized bed and a pyrolysis bed according to claim 1, wherein the gas distribution body is cone-shaped.
The apparatus for implementing gasification of raw coal (A) by combining a circulating fluidized bed and a pyrolysis bed according to claim 1, wherein a top portion of the central cylinder of the cyclone separator is in communication with the top portion of the deposition chamber via the second coal gas pipe.
A gasification method for operating an apparatus according to claim 1, comprising:
a. combusting, fluidizing, and gasifying raw coal (A) in an environment with a temperature of 900°C to 1200°C in a circulating fluidized bed gasification furnace (2) preliminarily to generate coal gas, carbon-containing fly ash (C) and semicoke (B), and feeding the carbon-containing fly ash and the semicoke into a cyclone separator together with the coal gas;

b. introducing the coal gas, the carbon-containing fly ash, and the semicoke in the circulating fluidized bed gasification furnace into the cyclone separator from an upper portion of the cyclone separator, introducing separated semicoke into a pyrolysis bed gasification furnace (301, 303), introducing a gasification agent into a bottom portion of the pyrolysis bed gasification furnace, and combusting the separated semicoke in the pyrolysis bed gasification furnace for further pyrolysis and gasification;

c. introducing coal gas generated in the pyrolysis bed gasification furnace, the coal gas and the carbon-containing fly ash generated in the circulating fluidized bed gasification furnace into a deposition chamber through a central cylinder of the cyclone separator, and discharging coal slag (D) from a slag pan at the bottom portion of the pyrolysis bed gasification furnace; and

d. introducing the carbon-containing fly ash deposited in the deposition chamber into a first mixture gas distribution chamber on a bottom portion of the circulating fluidized bed gasification furnace by using a conveyor (5) and a fly ash pipe (9), and then introducing the carbon-containing fly ash heated along with a gasification agent into the circulating fluidized bed gasification furnace for circulating gasification and combustion.
The method according to claim 5, wherein the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is mixed gases of air and vapor, and the semicoke is combusted and pyrolyzed in the pyrolysis bed gasification furnace.
The method according to claim 5, wherein the gasification agent introduced into the bottom portion of the circulating fluidized bed gasification furnace is mixed gases of air, vapor and oxygen, and the raw coal is combusted and pyrolyzed in the circulating fluidized bed gasification furnace.
The method according to claim 5, wherein the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is mixed gases of air, vapor and oxygen, and the semicoke is combusted and pyrolyzed in the pyrolysis bed gasification furnace.