JP2001329272A - Heat recovery boiler for coal gasification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deposition of dust on a group of heat exchanger tubes in a heat recovery boiler for coal gasification. SOLUTION: A connecting tube 10 is provided at the top of a heat recovery boiler 11, and a gas formed in a coal gasification furnace is led into a heat exchanger boiler 11 through this connecting tube 10. A funnel-shaped gas flow contrarotatable rotor 34 is installed opposite to the opening end 44 of the connecting tube 10 in the heat exchanger boiler 11, and the opening area of the upper opening portion 45A of this gas flow contrarotating container 34 is set at the one equal to or greater than that of the opening end 44. The lower opening portion 45B of the gas flow contrarotating rotor 34 is connected to a dust recover tube 33. Then, the flow of the formed gas 46 jetted from the opening end 44 is stopped by the flow resistance of the dust recovery tube 33 and contrarotated and, simultaneously, the dust present in the formed gas 46 is allowed to flow into the dust recovery tube 33 by the inertia which the dust possesses. Hereby, dust is separated from the formed gas 46, and the formed gas after the dust separation by the contrarotation of the flow direction is allowed to flow into a group of heat exchanger tubes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal gasifier, and more particularly to a coal installed downstream of a coal gasifier for cooling dust-containing high-temperature generated gas from the coal gasifier and recovering heat. The present invention relates to a heat recovery boiler for gasification.

[0002]

2. Description of the Related Art Since the oil crisis, in the course of fuel diversification, coal utilization technology has been developed. In particular, the integrated coal gasification combined cycle system is expected to have higher energy efficiency than the conventional pulverized coal-fired thermal power generation system.

In the integrated coal gasification combined cycle system, a gas turbine is driven by generated gas discharged from a coal gasifier to generate power. There is also a system in which a hydrogen-containing gas produced by a coal gasifier is purified and supplied as a raw material for a fuel cell power generation system. The product gas discharged from the coal gasifier contains corrosive gases such as hydrogen sulfide in addition to the main components such as hydrogen, carbon monoxide, and methane, and is in a high-temperature, high-pressure state, and is sent to a downstream process. Before being led to a heat recovery boiler, it is cooled and recovered. In addition, since the generated gas contains a large amount of dust composed of unreacted char, scattered slag, ash, etc., a cyclone dust collector and a dust filter are provided downstream of the heat recovery boiler, and dust is collected by these. In general, the gas is recharged into the gasification chamber of the gasification furnace.

A conventional heat recovery boiler for coal gasification will be described with reference to FIGS. Here, FIG. 13 shows a CC section of FIG. 12, and FIG. 14 shows a DD section of FIG. The coal gasifier 1 has a pressure vessel 2, in which a gasification chamber 3, a gasifier heat recovery unit 4, and a slag tap 5 are housed. The gasification chamber 3 is provided with an upper burner 7 and a lower burner 8 to which raw pulverized coal and a gasifying agent are supplied, and a recycle char burner 9 to be supplied with a recycle char and a gasifying agent. A connecting pipe 10 is provided at an upper part of the coal gasifier 1,
This connecting pipe 10 is connected to the top of the heat recovery boiler 11. The gas generated in the gasification chamber 3 is supplied to the top of the heat recovery boiler 11 through the gasification furnace heat recovery unit 4 and the communication pipe 10.

The heat recovery boiler 11 has a pressure vessel 12,
A gas flow path space 14 surrounded by a membrane water wall 13 is formed in the pressure vessel 12, and a plurality of heat transfer tube groups 15 are arranged therein. This is a measure for protecting the pressure vessel 12 from high temperature and corrosive environment. The generated gas is cooled when passing through the gas flow space 14.

[0006] The cooled product gas is supplied to the heat recovery boiler 11.
From the bottom through the heat recovery boiler outlet line 32 to the cyclone dust collector 19 and the dust filter 22 to remove dust. The product gas after dust removal is sent to a downstream process. On the other hand, the dust collected by the cyclone dust collector 19 is supplied to the feed hopper 25 via the cyclone hopper 20 and the lock hopper 21, and is sent to the recycle chamber 9 by the ejector 27 via the rotary valve 26. The dust collected by the dust filter 22 is also supplied to the filter hopper 23 and the lock hopper 24.
, And is sent to the recycle chamber 9 together with the dust collected by the cyclone dust collector 19. In the figure, reference numeral 29 denotes nitrogen gas for sending dust to the recycling carburetor 9.

As described above, in the conventional heat recovery boiler for coal gasification, a generated gas containing a large amount of dust is supplied to the heat transfer tube group. Deposition increases thermal resistance and significantly reduces heat transfer efficiency. In consideration of such a decrease in heat transfer efficiency, predetermined cooling and heat recovery necessarily require an enormous heat transfer surface.

Therefore, Japanese Patent Application Laid-Open No. 5-332162 discloses that a heat recovery boiler is provided with a partition wall in a pressure vessel to form a U-shaped gas flow path and to increase the gas flow rate to promote heat transfer. Proposed. Also, Japanese Patent Application Laid-Open No. Sho 61-2212
No. 93 proposes that a soot blow device is provided and dust accumulated on the heat transfer tube is wiped off by the soot blow device.

[0009]

However, in the heat recovery boiler, a gas flow furnace space surrounded by a membrane water wall is formed in a pressure vessel, and a plurality of heat transfer tube groups are disposed inside the gas flow furnace space. Further, providing a partition wall to form a U-shaped gas flow path is not preferable because the structure becomes complicated.

Further, even if a sootblowing device is provided, the range in which dust can be efficiently removed only extends from the nozzle injection position to the third to fifth stage tube banks, so that a large number of sootblowing devices must be installed. . In addition, the dust concentration of the generated gas is high, and dust accumulates on the heat transfer tube in a relatively short time. Therefore, the dust must be removed frequently by a soot blow device. On the other hand, if a large amount of dust accumulates on the heat transfer tube, the thermal resistance increases, and the heat transfer efficiency decreases significantly.

A cyclone dust collector and a dust filter may be provided in the middle of the connecting pipe from the coal gasification furnace to the top of the heat recovery boiler. However, the equipment cost is high temperature, high pressure, corrosive environment and equipment cost is low. In addition to the bulkiness, it is anticipated that a flow path blockage trouble due to sintering of dust adhering to the cyclone wall surface and the filter surface is expected, which is not an advantageous measure.

An object of the present invention is to provide a heat recovery boiler for coal gasification that can prevent dust from accumulating on a heat transfer tube group simply by providing equipment having a simple structure.

[0013]

In order to solve the above-mentioned problems, the present invention introduces a high-temperature generated gas generated in a coal gasifier into a top of a heat recovery boiler through a connecting pipe, and heats the boiler. In the heat recovery boiler for coal gasification, which is brought into contact with the heat transfer tube group in the inside and discharged from the bottom of the heat recovery boiler to cool the generated gas and recover heat, in the coal gasification heat recovery boiler, By inverting the flow direction and moving the dust contained in the generated gas in the generated gas ejection direction by the inertia of the dust,
Dust separation means for separating dust from the generated gas and flowing the generated gas after dust separation to the heat transfer tube group is provided at a top portion in the heat recovery boiler.

According to the above configuration, the dust in the generated gas is separated by the dust separating means, and the generated gas containing little dust flows through the heat transfer tube group. Therefore, it is possible to prevent dust from being deposited on the heat transfer tube group. it can.

Specifically, according to the present invention, a high-temperature generated gas generated in a coal gasifier is introduced into a top portion of a heat recovery boiler through a connecting pipe, and brought into contact with a heat transfer tube group in the heat recovery boiler.
In the heat recovery boiler for coal gasification, which is discharged from the bottom of the heat recovery boiler and cools the generated gas and recovers heat, the heat recovery boiler is provided to face the open end of the connecting pipe and is equal to or larger than the opening area of the open end A substantially funnel-shaped gas flow inverter having an opening area of, and a dust recovery pipe connected to a bottom opening of the gas flow inverter and having a flow resistance, wherein the generated gas ejected from an opening end of the communication pipe is provided. By blocking the flow with the flow resistance of the dust collecting pipe and inverting it along the gas flow inverter, and causing the dust contained in the generated gas to flow into the dust collecting pipe by the inertia of the dust, The method is characterized in that dust is separated from the generated gas, and the generated gas after dust separation in which the flow direction is reversed flows to the heat transfer tube group.

According to the above configuration, the product gas ejected from the opening end of the connecting pipe tries to flow into the dust collecting pipe from the gas flow inverter, but flows into the dust collecting pipe due to the flow resistance of the dust collecting pipe. And flows in reverse along the gas flow inverter. On the other hand, the dust in the generated gas flows into the dust collection pipe due to the inertial force applied to the dust by the ejection of the generated gas. Thereby, dust can be easily separated from the generated gas.

In constituting the heat recovery boiler for coal gasification, the following components can be added. (1) The gas flow inverter and the dust collection pipe are provided with a cooling mechanism, and are cooled by the cooling mechanism. (2) The gas flow inverter and the dust recovery pipe are arranged in a gas flow space surrounded by a membrane water wall in the heat recovery boiler. (3) The gas flow inverter and the dust recovery pipe are arranged in a space between an inner wall of the heat recovery boiler and a water wall of the membrane. (4) A heat recovery boiler outlet line provided at the bottom of the heat recovery boiler and through which generated gas discharged from the bottom of the heat recovery boiler flows, and temporarily storing dust that flows into the dust recovery pipe and is separated from the generated gas. A hopper, a pressurizing means for pressurizing the inside of the hopper, and a dust return line for returning dust in the hopper to the heat recovery boiler outlet line by being pressurized by the pressurizing means. By means, the pressure in the hopper is maintained at a pressure higher than the pressure in the heat recovery boiler outlet line and lower than the pressure in the dust recovery pipe. (5) A heat recovery boiler outlet line provided at the bottom of the heat recovery boiler and through which generated gas discharged from the bottom of the heat recovery boiler flows, and temporarily storing dust that flows into the dust recovery pipe and is separated from the generated gas. And a gas return line for returning generated gas in the hopper to the heat recovery boiler outlet line. (6) Gas flow rate adjusting means for adjusting the flow rate of generated gas after dust separation is provided.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIGS. Here, FIG. 1 is a schematic configuration diagram of a heat recovery boiler for coal gasification according to Embodiment 1, and FIG.
3 is a sectional view taken along line BB of FIG. 2; FIG. 4 is a detailed sectional view of part a of FIG. 1; FIG. 5 is a detailed sectional view of part b of FIG. It is.

As shown in the figure, a connecting pipe 10 is provided at the top of the heat recovery boiler 11, and this connecting pipe 10 is connected to a coal gasification furnace (see FIG. 12). The generated gas containing high-density corrosive high-temperature and high-pressure corrosive gas is supplied to the connecting pipe 1.
0 and is supplied to the top of the heat recovery boiler 11. The heat recovery boiler 11 has a pressure vessel 12.
In the gas flow passage space 14 surrounded by the membrane water wall 13
Are formed, and a plurality of heat transfer tube groups 15 are arranged inside the gas flow passage space 14.

In the present embodiment, the open end 4 of the connecting pipe 10
4 is disposed near the top of the heat recovery boiler 11 and substantially at the center of the cross section of the gas flow space 14. A substantially funnel-shaped gas flow inverter 34 is arranged opposite to the open end 44 of the connecting pipe 10. The area of the upper opening 45A of the gas flow inverter 34 is equal to or larger than the area of the opening end 44 of the connecting pipe 10, and the upper opening 45A of the gas flow inverter 34 and the opening end of the connecting pipe 10 are formed. A space is provided between the gas passage and the gas passage 44 to allow the gas to flow.

A dust collecting pipe 33 is provided below the gas flow inverter 34. The dust collection pipe 33 has a double pipe structure including an inner pipe 49 and an outer pipe 50, and the inner pipe 49 is connected to a lower opening 45 </ b> B of the gas flow inverter 34. The gas flow inverter 34 also has a double-pipe structure, and the outer pipe is connected to the outer pipe 50 of the dust recovery pipe 33. Further, the inner pipe 40 of the dust collecting pipe 33 is arranged so that its central axis passes through the center of the open end 44 of the connecting pipe 10.

The lower part of the dust recovery pipe 33 communicates from the bottom of the heat recovery boiler 11 to the outside. Cooling water is supplied to a lower part of the dust collecting pipe 33 having a double pipe structure from a cooling water inlet 38, and the cooling water flows between the outer pipe 50 and the inner pipe 49 to the gas flow inverter 34 while collecting dust. The pipe 33 and the gas flow inverter 34 are cooled and then discharged from a cooling water outlet 39 at the upper part of the gas flow inverter 34.

A rotary valve 35 is attached to a lower portion of the dust collecting pipe 33, and a dust hopper 3 is provided downstream thereof.
6. A rotary valve 37 is provided, and a dust return line 40 extending from the rotary valve 37 to the heat recovery boiler outlet line 32 is provided. Further, pressure detectors 41 and 41 'are provided, and these pressure detectors 41 and 41' are provided.
Thereby, the gas pressure inside the heat recovery boiler outlet line 32 and the dust recovery pipe 33 is detected. A pressurizing line 4 having a pressure regulator 42 on the way
3 is attached. Then, the pressure adjuster 42 takes in the detection signals from the pressure detectors 41 and 41 ′ and adjusts the pressure in the dust hopper 36. That is, the pressure regulator 42 determines that the pressure in the dust hopper 36 is equal to or higher than the gas pressure of the heat recovery boiler outlet line 32 and the dust recovery pipe 33
The pressure in the pressurization line 43 is adjusted so as to be equal to or less than the gas pressure in the inside.

The heat recovery boiler outlet line 32 is connected to the cyclone dust collector 19, from which the downstream structure is
This is the same as the above-described prior art. In the drawing, reference numeral 16 denotes a plurality of heat transfer tubes constituting the heat transfer tube group 15;
6 are upper headers 17a and 17b and lower header 17
a, 17b.

Next, the operation of the heat recovery boiler for coal gasification configured as described above will be described. A high-concentration dust-containing gas 46 containing high-temperature and high-concentration dust is ejected from the opening end 44 of the connecting pipe 10 toward the upper opening 45A of the gas flow inverter 34. Then, the ejected dust-containing gas 46 tries to flow into the dust collecting pipe 33 from the lower opening 45B of the gas flow inverter 34, but the inner surface of the dust collecting pipe 33 has flow resistance, and Since the rotary valve 35 is provided below the recovery pipe 33, the dust-containing gas 46 cannot flow into the dust recovery pipe 33, and reverses the flow direction and flows along the funnel-shaped inner surface of the gas flow inverter 34. . At this time, since the dust in the dust-containing gas 46 has a large inertia, the dust is separated from the gas stream to become separated dust 47 and settles down in the dust collection pipe 33 by gravity.

Since the pressure in the dust hopper 36 is set lower than the pressure in the dust collecting pipe 33, a slight gas flow occurs in the dust collecting pipe 33 as the rotary valve 35 rotates. This slight gas flow promotes sedimentation of dust particles in the dust recovery pipe 33, and has a great effect in preventing dust from being re-entrained in the reversing gas flow at the gas flow reversing device 34. is there. The low-concentration dust-containing gas 48 from which the dust has been separated flows from the outer edge of the gas flow inverter 34 to the heat transfer tube group 15 in the gas flow space 14. Dust accumulation is greatly reduced, and cooling of the dust-containing gas 48 and heat recovery from the dust-containing gas 48 are performed efficiently. As a result, according to the present embodiment, the heat transfer area of the heat transfer tube group 15 can be reduced, that is, the heat recovery boiler 11 can be downsized.
In addition, the installation interval of soot blow for removing accumulated dust can be widened, and the consumption of soot blow gas can be reduced.

In the present embodiment, the dust hopper 3
6 is controlled to be equal to or lower than the pressure of the dust recovery pipe 33 and equal to or higher than the pressure of the heat recovery boiler outlet line 32, so that the flow rate of the gas flowing from the dust recovery pipe 33 can be appropriately maintained and the heat recovery boiler outlet is controlled. Dust can be reliably returned to the line 32. Further, by providing the dust hopper 36, it is possible to prevent the dust collection pipe 33 from being closed due to a sudden increase in the amount of dust due to a load change or the like.

The dust returned to the heat recovery boiler outlet line 32 is agglomerated and has a large apparent particle size.
In addition, it also collides with relatively small particles that have not been separated by the gas flow inverter 34, and also has an effect of capturing the small particles.
Therefore, the separation efficiency in the cyclone dust collector 19 is also improved.

Further, the gas flow reversing device 34 and the dust collecting pipe 33 are water-cooled, so that the adhered dust and the collected dust do not sinter even in the high temperature portion at the top of the heat recovery boiler 11.

(Embodiment 2) FIG. 6 shows Embodiment 2 of the present invention. In the present embodiment, the dust collection pipe 33 includes a large-diameter pipe 51 and a small-diameter pipe 52, and four small-diameter pipes 52 are arranged around the large-diameter pipe 51. By flowing cooling water through these small-diameter tubes 52, the large-diameter tubes 52 can be cooled. The number of small-diameter tubes 52 is not limited to four, and may be any number.

According to the present embodiment, since the structure is simpler than that of the double tube system, the manufacture becomes easy.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. In the present embodiment, the end of the dust collection pipe 33 is directly connected to the dust hopper 36.
The flow rate of the gas flowing through the dust recovery pipe 33 is naturally determined according to the flow resistance in the heat recovery boiler 11 and the flow resistance from the dust recovery pipe 33 to the dust return line 40.

According to the present embodiment, the rotary valve 1
The table can be omitted, and a simple configuration can be realized.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention. In the present embodiment, the lower part of the dust recovery pipe 33 is directly connected to the dust hopper 36, and only the gas is returned from the upper part of the dust hopper 36 to the heat recovery boiler outlet line 32 via the gas return line 57. Adjustment of the gas flow rate in the dust collection pipe 33 is performed by a flow rate control valve 55 provided in the gas return line 57. The dust separated by the dust hopper 36 is sent from the lock hopper 53 to the feed hopper 25 via the dust transfer line 56, and sent to the recycling chamber together with the dust collected by the cyclone dust collector 19 and the dust filter 22.

According to the present embodiment, the dust collection pipe 33
The adjustment of the gas flow rate in the inside can be finely controlled, and the load on the cyclone dust collector 19 can be reduced.

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention. The cross-sectional shape of the dust collecting pipe is not limited to a circular shape, but may be a rectangular shape as shown in FIG. The dust collection pipes 54 are arranged between the heat transfer tube groups 15. When the cross section is rectangular, the composition of the heat transfer tube group including the header 17 and the heat transfer tubes 16 is simplified.

(Sixth Embodiment) FIG. 10 shows a sixth embodiment of the present invention. The cross-sectional shape of the gas flow inverter is not limited to a circular shape, but may be a rectangular shape as shown in FIG. Further, the shape of the gas flow inverter does not need to be limited to a funnel shape, and the dust recovery tube 33 'may be extended as it is. However, the area of the opening corresponding to the upper opening of the gas flow inverter needs to be larger than the area of the opening end 44 of the communication pipe 10.

(Seventh Embodiment) FIG. 11 shows a seventh embodiment of the present invention. In the present embodiment, the gas flow inverter 34 and the dust recovery pipe 33 are arranged in a space between the pressure vessel 12 of the heat recovery boiler and the membrane water wall 13.

In this way, since the dust collection tubes 33 do not pass between the heat transfer tube groups 15, the structure of the heat transfer tube group 15 is simplified, and the arrangement is also facilitated.

[0040]

As described above, according to the present invention,
Even if the product gas containing a large amount of dust is supplied to the heat recovery boiler, most of the dust in the product gas is removed, and the product gas containing little dust flows to the heat transfer tube group.
No dust accumulates on the heat transfer tube banks. As a result, it is possible to realize a small and highly reliable heat recovery boiler with a small decrease in heat transfer efficiency in the heat transfer tube group.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a heat recovery boiler for coal gasification according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a detailed view of a part a of FIG. 1;

FIG. 5 is a detailed view of a portion b in FIG.

FIG. 6 is a cross-sectional view of a dust collection pipe according to Embodiment 2 of the present invention.

FIG. 7 is a main part configuration diagram of a heat recovery boiler for coal gasification according to Embodiment 3 of the present invention.

FIG. 8 is a main part configuration diagram of a coal gasification heat recovery boiler according to Embodiment 4 of the present invention.

FIG. 9 is a diagram showing a main configuration of a dust collection pipe according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a main configuration of a dust collection pipe according to a sixth embodiment of the present invention.

FIG. 11 is a main part configuration diagram of a heat recovery boiler for coal gasification according to a seventh embodiment of the present invention.

FIG. 12 is a configuration diagram of a conventional heat recovery boiler for coal gasification.

FIG. 13 is a sectional view taken along the line CC of FIG.

FIG. 14 is a sectional view taken along line DD of FIG. 13;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasification furnace 10 Connecting pipe 11 Heat recovery boiler 12 Pressure vessel 13 Membrane water wall 14 Gas flow path space 15 Heat transfer pipe group 16 Heat transfer pipe 19 Cyclone dust collector 22 Dust filter 32 Heat recovery boiler outlet line 33 Dust recovery pipe 34 Gas Flow inverters 35, 37 Rotary valve 36 Dust hopper 38 Cooling water inlet 39 Cooling water outlet 40 Dust return line 41, 41 'Pressure detector 42 Pressure regulator 43 Pressurizing line 44 Opening end of communication pipe 45A Upper part of gas flow inverter Opening 45B Lower opening of gas flow inverter 49 Inner tube of dust collection tube 50 Outer tube of dust collection tube 51 Large diameter tube of dust collection tube 52 Small diameter tube of dust collection tube 54 Dust collection tube 55 Flow control valve 57 Gas Return line

Continuation of the front page (72) Inventor Akio Ueda 3-36 Takara-cho, Kure-shi, Hiroshima Prefecture Inside Babcock Hitachi Kure Research Institute (72) Inventor Naomi Yoshida 3-36 Takara-cho, Kure-shi Hiroshima Prefecture Inside Babcock Hitachi Kure Research Institute F-term (reference) 4H060 AA03 BB25 CC03 DD24

Claims (8)

[Claims] 1. A high-temperature generated gas generated in a coal gasifier is introduced into the top of a heat recovery boiler via a connecting pipe, brought into contact with a group of heat transfer tubes in the heat recovery boiler, and discharged from the bottom of the heat recovery boiler. In the coal gasification heat recovery boiler that cools and heat recovers the generated gas, the flow direction of the generated gas ejected from the opening end of the connecting pipe is reversed, and the dust contained in the generated gas is removed. By moving the generated gas by the inertia of the dust in the direction of ejecting the generated gas to separate the dust from the generated gas and flowing the generated gas after dust separation to the heat transfer tube group, a dust separation unit is provided in the heat recovery boiler. A heat recovery boiler for coal gasification, provided on the top. 2. The high-temperature generated gas generated in the coal gasifier is introduced into the top of the heat recovery boiler via the connecting pipe, brought into contact with the heat transfer tube group in the heat recovery boiler, and discharged from the bottom of the heat recovery boiler. In the heat recovery boiler for coal gasification for cooling the generated gas and recovering heat, a substantially funnel provided opposite to the open end of the connecting pipe and having an opening area equal to or greater than the open area of the open end And a dust collection pipe connected to a bottom opening of the gas flow inverter and having a flow resistance. The flow of the generated gas ejected from an open end of the communication pipe is provided by the dust collection pipe. Flow along the gas flow inverter, and by causing the dust contained in the generated gas to flow into the dust collection pipe by the inertia of the dust, the dust generated from the generated gas is reduced. Was separated, the heat recovery boiler coal gasification, characterized in that flowing the product gas after dust separation flow direction reversed to the heat transfer tube group. 3. The heat recovery boiler for coal gasification according to claim 2, wherein the gas flow inverter and the dust recovery pipe have a cooling mechanism, and are cooled by the cooling mechanism. Heat recovery boiler. 4. The heat recovery boiler for coal gasification according to claim 2, wherein the gas flow inverter and the dust recovery pipe are provided in a gas flow space surrounded by a membrane water wall in the heat recovery boiler. A heat recovery boiler for coal gasification, which is disposed. 5. The heat recovery boiler for coal gasification according to claim 2, wherein the gas flow inverter and the dust recovery pipe are arranged in a space between an inner wall of the heat recovery boiler and a water wall of the membrane. A heat recovery boiler for coal gasification, characterized in that: 6. The heat recovery boiler for coal gasification according to claim 2, wherein the heat recovery boiler outlet line is provided at the bottom of the heat recovery boiler and through which generated gas discharged from the bottom of the heat recovery boiler flows, and the dust. A hopper for temporarily storing dust separated from the product gas by flowing into the collection pipe, a pressurizing means for pressurizing the inside of the hopper, and pressing the dust in the hopper by being pressurized by the pressurizing means. A dust return line returning to a heat recovery boiler outlet line, wherein the pressure in the hopper is maintained at a pressure equal to or higher than the pressure in the heat recovery boiler outlet line and equal to or lower than the pressure in the dust recovery pipe by the pressurizing means. A heat recovery boiler for coal gasification. 7. The heat recovery boiler for coal gasification according to claim 2, wherein a heat recovery boiler outlet line provided at the bottom of the heat recovery boiler and through which generated gas discharged from the bottom of the heat recovery boiler flows; A coal gas, comprising: a hopper for temporarily storing dust separated from the product gas by flowing into the recovery pipe; and a gas return line for returning the product gas in the hopper to the heat recovery boiler outlet line. Heat recovery boiler. 8. The heat recovery boiler for coal gasification according to claim 2, further comprising gas flow rate adjusting means for adjusting the flow rate of the generated gas after dust separation. .