JPH0778223B2 - Gasification furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-bed type gasifier for gasifying a fine powdered solid carbonaceous raw material typified by coal, in which the unburned portion of the raw material is transferred to recover the heat of the produced gas. The present invention relates to a gasification furnace capable of preventing adhesion to a heat pipe surface and recovering heat without lowering the heat transfer efficiency of the heat transfer pipe surface.

[0002]

2. Description of the Related Art Conventionally, various systems such as a fixed bed, a fluidized bed, and a gas bed have been proposed as a furnace system for gasifying a solid carbonaceous raw material such as coal. Among these methods, the airflow layer method is a method in which the raw material is made into fine powder and is supplied together with an oxidizing agent such as oxygen or air into the furnace at a temperature (1300 to 1600 ° C) above the melting point of the ash of the raw material, It is a method of converting combustibles into gas and ash into slag. Therefore, the airflow layer method has characteristics such as high gasification efficiency, a wide range of applicable coal types, and excellent environmental compatibility as compared with other methods. Therefore, the gas taken out from this system is suitable for producing fuels such as combined cycle power generators and fuel cells, and raw materials such as syngas, and is being developed domestically or internationally.

A block diagram of a conventional gasifier is shown in FIG. A pulverized carbonaceous solid raw material typified by coal is charged together with an oxidizing agent such as oxygen or air into the gasification section 11 kept at a temperature higher than the melting temperature of the raw material ash from the burners 8 and 9 to remove combustible components of the raw material. The ash is converted into slag, respectively, into a gas rich in hydrogen and carbon monoxide. The slag that has dropped from the slag tap 27 into the slag cooling water 18 below is water granulated by thermal stress due to the temperature difference. The heat of the generated gas is heat-exchanged with the heat transfer tube 25 by radiant heat transfer, and then the generated gas reaches the downstream deduster such as a cyclone through the generated gas line 19.

A cross section of the heat recovery section 13 is shown in FIG. The heat transfer tube 25 has a structure in which a tube and a flat plate are assembled by welding or the like, is concentric with the gasification furnace 10, and is a space portion 24 along the inner peripheral surface of the gasification furnace 10 and the inner peripheral surface of the furnace. It has the same structure as a membrane used in general boiler water walls, etc. Since the internal pressure of the heat recovery section 13 through which the generated gas passes is as high as several tens of atmospheres, the heat transfer pipe 25 is stored in the gasification furnace 10 which is a pressure vessel. Further, the space 24 between the heat transfer tube 25 and the gasification furnace 10
The purge gas is injected so that the pressure is higher than the internal pressure of the heat recovery unit 13. This prevents a high-temperature generated gas containing hydrogen sulfide or water vapor from flowing into the space 24. Therefore, as the purge gas injected from the purge gas line 3, a recycled gas of a product gas purified by removing nitrogen, carbon dioxide gas, corrosive hydrogen sulfide, or the like is used.

[0005]

In order to increase the gasification efficiency in the gasification section 11, generally, as shown in JP-A-59-176391 and JP-A-59-86624, a burner 8,
9 is arranged in the gasification section 11 so as to be in contact with a virtual circle, and a strong swirl flow is generated in the flow of the raw material particles ejected from the burners 8, 9 to generate the gas of the raw material particles. The residence time in the conversion section 11 is increased. At the upper part of the gasification section 11, there is a contracting section 26 for contracting the flow of the produced gas, and at the lower section of the heat recovery section 13, there is the contracting section 2.
A throttle portion 30 having the same inner diameter as 6 is arranged. The flow of the generated gas becomes a strong swirl flow in the contracting section 26, and the narrowing section 3
When flowing out from 0, it becomes a swirling flow along the inner side surface of the throttle portion 30. In addition to this, the flow of the generated gas becomes a columnar vortex flow in the central portion of the heat recovery section 13, and a part thereof becomes a gas flowing at high speed in the center of the columnar vortex. Regarding this columnar vortex, "Natural vortex and engineering vortex" (Translated by Hideo Ohashi, Translated by Yamaguchi, 145P, Asakura Shoten, June 1988)
"The columnar vortex is generated because the velocity in the axial direction is applied when the outlet portion of the high-speed swirling flow is reduced."

As described above, a part of the produced gas flowing out from the throttle portion 30 forms a columnar vortex at the center of the heat recovery portion 13 and flows directly to the outlet of the produced gas line 19, so that heat exchange with the heat transfer tube 25 is not sufficiently performed. Further, a part of the flow of the generated gas forms a columnar vortex, so that the gas flow velocity in the heat transfer tube 25 that exchanges heat in the heat recovery unit 13 also becomes low. Therefore, the gas flow velocity including the char of the raw material generated in the gasification section and scattered from the gasification section becomes small, and the particle size of the char is very small, 10 μm or less, so that the intermolecular force of the char, electrostatic force, etc. The heat is transferred to the heat transfer tube 2
Adhere to 5. As a result, the attached char becomes a heat transfer resistance, so that the heat recovery amount of the generated gas in the heat recovery part 13 is reduced. When the heat recovery amount of the generated gas decreases, the sensible heat of the generated gas passing through the generated gas line 19 increases.
The recovery of the energy of the produced gas deteriorates. Furthermore, since the temperature of the gas passing through the produced gas line 19 does not drop, it adversely affects subsequent equipment.

Even in a normal-pressure boiler that burns solid carbonaceous material such as coal to generate steam, the unburned content and ash content of the material are scattered along with the combustion gas, and the radiant heat transfer section or convective heat transfer section is used. Adhere to. In such a case, a method of injecting steam to the heat transfer section to remove it is adopted. Even if this method is applied to the above-mentioned gasification furnace, since the gasification furnace has a high pressure of several tens of atmospheres, the effect of removing the deposit is not so great. Further, when water vapor is injected into the produced gas, the partial pressure of the water vapor increases, and a shift reaction of water with carbon monoxide to form hydrogen and carbon dioxide proceeds, so that the composition of the produced gas changes. If steam is further added, even the calorific value of the produced gas per unit volume is changed. There is a plan to circulate the produced gas by the purified gasification in order to prevent the calorific value of the produced gas from changing, but it is necessary to further increase the pressure by several tens of atmospheres from the subsequent refined gas step,
It requires special equipment costs and significantly increases operating costs.

[0008] Incidentally, Japanese Utility Model Laid-Open No. 2-87048 discloses a device in which a fin for preventing swirling is installed at the outlet of the throttle portion. However, since the temperature of the gas when passing through the throttle portion is high, for example, a fin is used. A cooling means such as a water-cooled structure is required, and there is a high risk that molten slag that scatters with the char will adhere to and grow on the fins and block the gas flow path. In addition, when the swirl flow is canceled, the gas flow velocity near the heat transfer tube decreases, so char adheres to the heat transfer tube, increasing heat transfer resistance,
The heat recovery amount in the heat recovery unit will be reduced.

An object of the present invention is to provide a gasification furnace which suppresses a reduction in the amount of heat recovered from the produced gas without changing the composition and the calorific value of the produced gas at all.

[0010]

[Means for Solving the Problems] The above-mentioned problem is that the temperature in the furnace is maintained at least at the melting temperature of the ash of the fine powder solid raw material,
Further, in a pressurized furnace, a gasification section for converting a combustible content of the raw material into a produced gas composed of carbon monoxide and hydrogen and an ash content of the raw material into slag by using an oxidizing agent, and the gasification section. Gas generated in the gasification section, which includes a throttle section arranged above the gasification section and having an inner diameter smaller than that of the gasification section, and an expansion section located at an upper portion of the throttle section and having an inner diameter gradually increasing toward the upper section. A heat recovery part for recovering heat from the heat recovery part, a reduction part arranged above the heat recovery part and having an inner diameter successively reduced toward a generated gas line for sending the generated gas to the outside of the furnace, and arranged below the gasification part. In a gasification furnace including a slag cooling section in which cooling water for water granulating the slag flowing down is stored, the heat recovery of the resistor that blocks the columnar vortex formed by the flow of the generated gas is performed. Placed on top of the section and / or on the reduced section It is achieved in Rukoto.

[0011]

By disposing a resistor that blocks the columnar vortex formed by the generated gas flow in the upper part of the heat recovery part and / or the reduced part above the heat recovery part, the columnar vortex formed by the generated gas flow is reduced. To be done. Therefore, the flow of the high-speed generated gas flowing through the center of the columnar vortex is also eliminated, and the energy possessed by these vortices and the high-speed flow is added to the swirling flow flowing along the heat transfer tube surface, and the flow velocity of the swirling flow is increased. Let Therefore, the amount of char attached to the heat transfer tube is reduced. Thus, even if the flow of the generated gas flowing out from the throttle portion forms a columnar vortex, the high temperature gas does not directly flow to the outlet of the heat recovery portion because it is blocked by the resistor. Therefore, the flow velocity of the swirling flow of the gas near the heat transfer tube increases, and the intermolecular force of the char and electrostatic force are blocked, so that the amount of the char adhering to the heat transfer tube decreases. As a result, the heat transfer resistance of the heat transfer tube due to the adhesion of char is reduced. Further, since the flow velocity of the swirling flow of the gas near the heat transfer tube increases, the gas boundary film becomes thin.
Therefore, the heat transfer resistance on the gas side is reduced. Since these two types of heat transfer resistances are reduced, the reduction of the heat recovery amount in the heat recovery unit is suppressed.

[0012]

FIG. 1 shows a first embodiment of the present invention. The gasification furnace main body 10 converts a combustible content of a fine powder solid raw material into a produced gas composed of hydrogen and carbon monoxide, and also converts an ash content of the raw material into a slag, and the gasification section 1
1, a slag cooling part 12 for accumulating the cooling water 18 and water-falling the slag 29 dropped, and the gasification part 11
Of the heat recovery part 13 which is disposed above the heat recovery part 13 and recovers the heat from the generated gas, and the inner diameter of the heat recovery part 13 which is disposed above the heat recovery part 13 is gradually reduced toward the generated gas line 19 which sends the generated gas out of the furnace. The reduction unit 32 is included.

The gasification section 11 penetrates the furnace wall 28,
One end is opened into the furnace, and the other end is connected to the raw material supply lines 4 and 5 and the oxidant supply lines 6 and 7, respectively, and burners 8 and 9;
Slag tap 27 that drops the slag 29 into the slag cooling unit 12
It is composed of. The heat recovery unit 13 includes a narrowed portion 30 having an inner diameter narrowed from that of the gasification portion, and an enlarged portion 31 located above the narrowed portion 30 and having an inner diameter gradually increasing toward the upper portion thereof. A heat transfer tube 25 arranged concentrically with a space 24 between the inner peripheral surface of the furnace 10 and the inner peripheral surface of the furnace.
And a boiler water supply line 14 and a boiler water outlet line 15 for a heat recovery boiler, which are composed of heat transfer tubes 25 for recovering the heat of the generated gas, and a purge gas line 3 for injecting a purge gas into the space 24. ing. Further, a conical resistor 17 having a bottom surface having a diameter of 0.4 times the diameter of the cylinder formed by the heat transfer tube 25 is arranged in the reduced portion 32 concentrically with the cylinder formed by the heat transfer tube 25. The raw material supply unit for supplying the raw material includes supply feeders 1 and 2 and the raw material supply line 4 connected to the supply feeders 1 and 2.
5 is included.

FIG. 2 shows the distribution of the flow velocity of the generated gas between the narrowed portion 30 and the enlarged portion 31 with and without the resistor 17. The vertical axis represents the flow velocity of the generated gas in the furnace axis direction, and the horizontal axis represents the measurement location in the diametrical direction of the cross section of the heat recovery section 13. Resistor 17
In the case where the resistor 17 is not provided, there is a portion having a large flow velocity in the central portion of the heat recovery unit 13, whereas when the resistor 17 is provided, the portion having a large flow velocity disappears. Therefore, in the conventional technique, the high-temperature generated gas in the gasification furnace directly flows out to the generated gas line 19, but the resistor 1
In the case where 7 is arranged, the resistor 17 blocks the high temperature generated gas from directly flowing to the generated gas line 19. Instead, it can be seen that the flow velocity near the heat transfer tube 25 is increasing. In an experiment conducted by the inventors regarding the relationship between the amount of char attached to the heat transfer tube 25 and the generated gas flow rate, if the gas flow rate is about 5 m / s or more, the adhesion of the char to the heat transfer tube 25 is almost zero. I found out. Therefore, since the gas flow velocity in the vicinity of the heat transfer tube 25 can be increased by disposing the resistor 17, char does not adhere to the heat transfer tube 25. Therefore, the heat transfer resistance of the heat transfer tube 25 due to the adhesion of char is eliminated. Further, since the gas flow velocity in the vicinity of the heat transfer tube 25 increases, the produced gas film becomes thin. As a result, the heat transfer resistance on the generated gas side is reduced. Since these two types of heat transfer resistances are small, it is possible to suppress a decrease in the amount of heat recovered from the generated gas in the heat recovery unit 13.

In order to prevent the char from adhering to the heat transfer tube 25, if the flow velocity of the generated gas is increased without reducing the area of the heat transfer tube, the cross-sectional area of the gas passage of the throttle portion 30 should be reduced. I can't help it. Then the heat recovery unit 1
Although the length of the generated gas in the flow direction of 3 is very large, and the height of the heat recovery unit 13 is very large, the height of the heat recovery unit 13 does not need to be changed in the apparatus of the present embodiment. .
In addition, since it is not necessary to carry out soot blowing with steam or recycled gas of generated gas, the initial equipment cost and the operating cost of the furnace can be saved.

In the present embodiment, since the resistor 17 is arranged in the reduction section 32 above the heat recovery section where the temperature is low, the resistor 1
No means for cooling 7 is required, and the slag scattered in the narrowed portion 30 of the heat recovery unit 13 is molten, but the scattered slag solidifies and loses its adhesiveness in the vicinity of the outlet, so the resistor Does not adhere to 17.

As a result of examining whether or not the columnar vortex formed by the flow of the produced gas can be reduced by changing the diameter of the bottom surface of the conical portion of the resistor 17 variously, the diameter is the diameter of the cylinder formed by the heat transfer tube 25. It turned out that it should be 0.3 times or more.

In this embodiment, the resistor 17 has a conical shape, but the same effect can be obtained with a disk.

A second embodiment of the present invention is shown in FIGS. The configuration of this embodiment is the same as that of the first embodiment, but the shape of the resistor arranged above the heat recovery portion is a partition plate 17A. The shape of the partition plate 17A is such that the centers of the long sides of two rectangles of the same shape whose short sides have a length 0.4 times the inner diameter of the heat recovery unit are crossed at the center of the cylinder of the heat recovery unit. The plate surface is arranged in the axial direction of the furnace.

A third embodiment of the present invention is shown in FIGS. The configuration of this embodiment is the same as that of the first embodiment, but the shape of the resistor arranged in the reduction portion 32 above the heat recovery portion is the partition plate 17B as in the second embodiment. . The shape of the partition plate 17B is such that the center of the upper and lower sides of two trapezoids of the same shape whose height is 0.4 times the inner diameter of the heat recovery section is at the center of the conical cylinder of the reduction section above the heat recovery section. They are crossed in a V shape, and their plate surfaces are arranged in the axial direction of the furnace.

Comparative examples for the second and third embodiments described above are shown in FIGS. 7 and 8. The structure of this comparative example is the same as that of the first embodiment, but a partition plate 17C having the same shape as that of the second embodiment is arranged in the pipe of the delivery port of the produced gas line 19. The partition plate 17C has a shape in which two square plates each having a side length slightly shorter than the inner diameter of the tube of the produced gas line 19 are crossed at the center of the tube. It is arranged in the axial direction.

In both the second and third embodiments, the columnar vortices formed by the flow of the produced gas could be reduced. However, in the comparative example, the columnar vortices could not be reduced.

From these results, two trapezoidal plates of the same type having a height of 0.4 times the inner diameter of the heat recovery section cylinder were installed at the center of the conical cylinder of the reduction section above the heat recovery section. It suffices that the crossed shape is arranged at least in the reduction portion above the heat recovery portion, and its surface is arranged in the axial direction of the furnace.

[0024]

According to the present invention, the columnar vortices formed by the flow of the produced gas are reduced and the gas flow velocity near the heat transfer tube is increased without changing the composition and the calorific value of the produced gas at all. By preventing the unburned component of the raw material from adhering to the heat transfer tube, it is possible to obtain a gasification furnace in which the amount of heat recovered from the produced gas is not reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a gasification furnace according to a first embodiment of the present invention.

FIG. 2 is a comparative graph of a flow velocity distribution in a heat recovery part of the produced gas of the gasification furnace according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional view in which a partition plate serving as a resistor is arranged in the gasification furnace according to the second embodiment of the present invention.

FIG. 4 is a transverse cross-sectional view taken along line IV-IV of the partition plate which is the resistor of FIG. 3 of the gasification furnace according to the second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view in which a partition plate which is a resistor is arranged in the gasification furnace of the third embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along line VI-VI of the partition plate which is the resistor of FIG. 5 of the gasification furnace of the third embodiment of the present invention.

FIG. 7 is a partial cross-sectional view in which a partition plate which is a resistor of a gasification furnace of a comparative example of the present invention is arranged.

8 is a cross-sectional view taken along line VIII-VIII of the partition plate which is the resistor of FIG. 7 of the gasification furnace of the comparative example of the present invention.

FIG. 9 is a block diagram of a conventional gasification furnace.

FIG. 10 is a cross-sectional view taken along the line X-X of a heat recovery unit of a conventional gasification furnace.

[Explanation of symbols]

1 Raw Material Supply Feeder 2 Raw Material Supply Feeder 3 Purge Gas Line 4 Raw Material Supply Line 5 Raw Material Supply Line 6 Oxidizing Agent Supply Line 7 Oxidizing Agent Line 8 Burner 9 Burner 10 Gasification Furnace Main Body 11 Gasification Section 12 Slag Cooling Section 13 Heat Recovery Section 14 Boiler water supply line 15 Boiler water outlet line 16 Burner 17 Resistor 17A Resistor (partition plate) 17B Resistor (partition plate) 17C Resistor (partition plate) 18 Slag cooling water 19 Generated gas line 20 Valve 21 Slag lock hopper 22 Cooling water inlet 23 Cooling water outlet 24 Space section 25 Heat transfer tube 26 Contraction section 27 Slag tap 28 Gasification furnace wall 29 Slag 30 Throttling section 31 Enlarging section 32 Reducing section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuntaro Koyama 7-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Toshimitsu Ikeda 3-1, Nakasode, Sodegaura City, Chiba Prefecture Coal Utilization Hydrogen Manufacturing Technology Research Association Driving Research Institute

Claims (3)

[Claims] 1. The temperature in the furnace is kept at least at the melting temperature of the ash of the fine powder solid raw material, and the combustible content of the raw material is composed of carbon monoxide and hydrogen by using an oxidizer in the pressurized furnace. In the produced gas, a gasification section for converting the ash content of the raw material into slag, respectively, a throttle section arranged above the gasification section and having an inner diameter narrowed from the gasification section, and an inner diameter at the upper part of the throttle section Of the heat recovery section for recovering heat from the gas generated in the gasification section, and an inner diameter disposed above the heat recovery section for expanding the generated gas outside the furnace. And a slag cooling section which is arranged below the gasification section and which stores cooling water for water granulating the slag flowing down. In the gasification furnace, the flow of the generated gas is A gasification furnace, wherein a resistor for blocking a columnar vortex to be formed is arranged in the upper part of the heat recovery part and / or the reduction part. 2. The upper part of the heat recovery section so that the resistor intersects the center of one side of a plurality of rectangular plates of the same shape with the axial center of the furnace so that the plate surfaces are in the axial direction of the furnace. The gasification furnace according to claim 1, wherein the gasification furnace is a partition plate disposed in the. 3. The resistor has a structure in which the centers of the upper and lower sides of a plurality of trapezoidal plates of the same shape are intersected with the axial center of the furnace so that the lower side faces the lower part of the furnace and the plate surfaces are in the axial direction of the furnace. The gasification furnace according to claim 1, wherein the gasification furnace is a partition plate arranged in the reduction unit.