JP2544267B2 - Coal partial gasification power generation method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine using a gas obtained by gasifying coal (pulverized coal) in a gasification furnace as a drive source,
In a combined cycle that combines a steam turbine driven by steam generated in a gasification furnace, a part of the input coal is gasified in the partial gasification furnace, and the remainder of the ungasified coal is pressurized and circulated. Complete combustion in a floor combustion furnace (char combustion furnace) due to excess air combustion up to an air ratio of 5.5
850 ℃, which is the temperature at which dust can be removed without baking and cooling
The Rukoto to produce the following combustion gas, to a power generation method and apparatus coal portion gasification which can be more efficient system conventional system.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional coal gasification combined cycle (IGCC). Reference numeral 10 is a pressurized complete gasification furnace, to which coal (pulverized coal) and pressurized air are supplied. Coal is gasified at around 1600 ° C., and after reacting with the coal charged in this gas at around 1300 ° C., saturated steam is superheated. The gas whose temperature has been lowered to around 850 ° C. is introduced into the dedusting device 12, char (residual coal) is separated, and this char is circulated to the gasification furnace 10. The gas from which the char has been separated is treated by the desulfurization device 14 and the precision dust removal device 16 and then introduced into the topping combustor 18 where it is completely combusted.
The combustion gas around 300 ° C. is introduced into the gas turbine 20. 22 is a generator. The air compressed by the air compressor 24 is supplied to the topping combustor 18 and the gasification furnace 10. 26 is an air booster. The gas from the gas turbine 20 is released to the atmosphere through the denitration device 28 and the exhaust heat boiler 30. The steam generated in the exhaust heat boiler 30 is introduced into the gasification furnace 10 and superheated, and then the steam turbine 32
Will be introduced. 34 is a generator. Steam turbine 32
The exhaust gas is cooled by the condenser 36 to be condensed water, which is supplied to the exhaust heat boiler 30 by the pump 38.

Further, Japanese Patent Laid-Open No. 61-241394 discloses a combined coal gasification combined cycle power generation consisting of a coal gasification furnace system, a dedusting desulfurization system, a gas turbine system, an air system, an exhaust gas boiler system and a steam turbine system. The device is described.

[0004]

The conventional coal gasification combined cycle shown in FIG. 3 has the following problems. (1) In the coal gasification reaction, about 30% of the total energy of gasified coal is converted into heat, which raises the temperature of the produced gas, but cools the gas to the allowable temperature of the dedusting device 12. There is a need. Therefore, about 20% of the heat is directly converted into steam, and is passed through the gas turbine 20 to the steam turbine 32. As a result, this 20% of energy does not form a combined cycle, and becomes the efficiency of only the steam turbine cycle, which reduces the overall system efficiency. This is called "heat bypass",
It is a major factor in reducing the efficiency of combined cycle coal power generation compared to the LNG combined cycle. (2) Since it is necessary to completely gasify coal, it is difficult to apply it to coal with poor reactivity.
The thermal bypass increases, reducing system efficiency. Further, the integrated coal gasification combined cycle power generation device described in Japanese Patent Laid-Open No. 61-241394 is for gasifying all coal in a coal gasification system, and in this publication, "Part of coal is gasified, The remainder of the ungasified coal was completed in a pressurized circulating fluidized bed combustion furnace by excess air combustion up to an air ratio of 5.5.
The temperature at which dust can be completely burned without cooling and 85
0 technical idea ℃ Ru to produce a following combustion gas ", nothing is described. The present invention has been made in view of the above points, and a char (residual coal) in which a portion of input coal is gasified by a partial gasification furnace for coal and is not gasified.
Was completely combusted in a pressurized circulating fluidized bed combustion furnace (char combustion furnace) under excess air conditions, and combustion gas at a dedustable temperature (about 850 ° C) or lower was generated without cooling, and was generated in a partial gasification furnace. After dedusting the gas, it is burned separately in the dedusted char combustion furnace combustion gas, and by driving the gas turbine with this combustion gas, the aforementioned thermal bypass amount is reduced,
The energy input to the gas turbine is increased, and high system efficiency can be obtained. Furthermore, since it is a partial gasification, the gasification condition becomes gradual and gasification becomes easier, and the gasification reactivity is low. It is an object of the present invention to provide a coal partial gasification power generation method and apparatus which can be applied to quality coal and have good coal type adaptability.

[0005]

In order to achieve the above object, the coal partial gasification power generation method according to the present invention drives a gas obtained by gasifying coal in a gasification furnace as shown in FIG. In the combined cycle power generation method in which the gas turbine 20 used as a power source and the steam turbine 32 driven by steam heated in the gasification furnace are combined, the following processes (a) to (d), that is, (a) The process of gasifying a part of the input coal in the partial gasification furnace 40, (b) The remaining part of the coal that was not gasified in the partial gasification furnace 40 is heated in the pressurized circulation fluidized bed combustion furnace 48 to an air ratio of 5.5. Until
Air was completely burned by excessive burning, without cooling
A process of generating a combustion gas at a dedustable temperature of 850 [deg.] C. or lower , (c) by mixing the combustion gas of the pressurized circulating fluidized bed combustion furnace 48 with dilution air, the effluent of the wake is removed. The process of lowering the combustion gas temperature to the allowable temperature of the dust device 50, (d) after degassing the gas generated in the partial gasification furnace 40, burning it in the dedusted pressurized circulating fluidized bed combustion furnace 48 exhaust gas, The process of introducing combustion gas into the gas turbine 20 is included.

In the above method, a part of the remaining coal that has not been gasified in the partial gasification furnace 40 is recycled to the partial gasification furnace 40, and the gasification rate is controlled so that the system efficiency is maximized. It is desirable to do. Further, in the above-described method of the present invention, fine powder of calcium oxide or calcium carbonate is supplied to the outlet gas flow path of the partial gasification furnace 40 to absorb and remove hydrogen sulfide, carbonyl sulfide, etc. in the gas to absorb sulfur. Dust removal device 4 for the remaining particles and unreacted particles
It is collected in 4 and supplied to the pressurized circulating fluidized bed combustion furnace 48.
In this case, it is desirable to use fine powder of calcium oxide or calcium carbonate having a particle size of 5 μm or less as the desulfurizing agent. In addition, the flow path temperature between the charging portion and the collecting portion of the calcium oxide or calcium carbonate fine powder is set to 1300 to 850 ° C.
It is desirable to adjust the range. Further, it is desirable to expand the cross section of the gas flow path downstream of the fine powder feeding section and adjust the gas flow velocity to a range of 100 to 10,000 times the terminal sedimentation velocity of the fine powder. When the particle size of the fine powder of calcium oxide or calcium carbonate exceeds 5 μm, the desulfurization reaction rate is low,
There are disadvantages that the desulfurization rate of the gas is low and the reaction rate of the desulfurization agent is low. Further, when the gas flow velocity is less than 100 times the final sedimentation velocity of the fine powder, there is a disadvantage that the gas flow passage diameter of the desulfurization reaction section becomes significantly large, while when the gas flow velocity exceeds 10,000 times the final sedimentation velocity of the fine powder. However, there is a disadvantage that the desulfurization reaction section flow path becomes extremely long when it is attempted to secure a contact time between the gas and the desulfurization agent for obtaining an effective desulfurization rate. In addition, the flow path temperature between the charging portion and the collecting portion of the fine powder of calcium oxide or calcium carbonate is 13
If the temperature exceeds 00 ° C, the temperature of the finely charged powder becomes too high,
There is a disadvantage in that the reaction equilibrium is disadvantageous and a sufficient desulfurization rate cannot be obtained. On the other hand, when the flow path temperature is lower than 850 ° C., the desulfurization reaction rate is low and a sufficient desulfurization rate cannot be obtained. There is inconvenience.

The partial coal gasification power generator of the present invention is shown in FIG.
As shown in, in a combined cycle power generation device that combines a gas turbine 20 that uses a gas obtained by gasifying coal in a gasification furnace as a drive source, and a steam turbine 32 that uses steam that is overheated in the gasification furnace as a drive source, Partial gasification furnace 40 for gasifying a part of input coal, and partial gasification furnace 40
The remaining part of the coal that was not gasified in the above was completely combusted by excessive air combustion up to an air ratio of 5.5, and degassed without cooling.
And dust can temperature at which 850 ° C. or less of the combustion gas pressure circulating fluidized bed combustion furnace 48 where Ru is generated, and a first dust removing unit 44 provided on the outlet gas flow path portion gasification furnace 40, pressure circulation It includes a second dust removing device 50 provided in the outlet gas flow path of the fluidized bed combustion furnace 48, and a combustor 18 provided downstream of the first dust removing device 44 and the second dust removing device 50. It is characterized by that. In the above-mentioned apparatus, a char distributor 46 is provided for distributing a part of the remainder of the coal that has not been gasified in the partial gasification furnace 40 to the partial gasification furnace 40 and the remainder to the pressurized circulating fluidized bed combustion furnace 48. Is desirable. Further, in the gas flow path between the partial gasification furnace 40 and the first dedusting device 44, an air flow entrained desulfurization reactor 42 using fine powder of calcium oxide or calcium carbonate as a desulfurizing agent is provided.

The coal (pulverized coal) charged into the partial gasification furnace 40 is partially gasified under the condition that 40 to 95%, preferably 50 to 70% thereof is gasified. 5 to 60% that was not gasified in the partial gasification furnace 40, preferably 3
0 to 50% of char (residual coal) is completely combusted in the pressurized circulating fluidized bed combustion furnace 48 by excessive air combustion up to an air ratio of 5.5.
850 ° C or lower, which is the temperature at which dust can be removed without cooling
To produce combustion gas . At this time, the pressurized circulating fluidized bed combustion furnace 48 is not a boiler, but is mixed with undiluted dilution air (for example, with an air ratio of about 5.5) to allow the dust removing apparatus to have an allowable temperature, for example, about 850 ° C. Lower the combustion gas temperature until. Then, after the fuel gas generated in the partial gasification furnace 40 is dedusted, the pressurized circulation fluidized bed combustion furnace 48 is dedusted separately.
After being burned in the combustion gas of, the gas is introduced into the gas turbine 20. Note that there is a maximum value of system efficiency for the following reasons. (1) As the gasification rate decreases (char combustion increases), thermal bypass decreases and efficiency improves (when gas turbine inlet temperature is constant). (2) As the amount of char increases, the amount of char combustion gas increases, the gas turbine inlet temperature decreases, and the efficiency decreases.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. However, the shape of the constituent devices described in this embodiment, the relative arrangement thereof, and the like, unless otherwise specified, are not intended to limit the scope of the present invention only to them, but merely illustrative examples. Nothing more. FIG. 1 shows an embodiment of the coal partial gasification power generator of the present invention. A pressurized partial gasification furnace 40 is supplied with coal (pulverized coal) and pressurized air (for example, around 30 kg / cm ² G). A part of coal is gasified at around 1600 ° C, and the melt is discharged as slag. Further, after reacting with the coal charged in this gas at around 1300 ° C., saturated steam is superheated. C in the gas cooled to around 850 ° C
aCO ₃ or CaO is added as a desulfurizing agent. This gas is a so-called entrain desulfurization reactor 4 which reacts with a sulfur compound while a fine powder of a desulfurizing agent is entrained in the gas.
Introduced in 2. Next, the desulfurized gas is introduced into the first dust removing device 44 (for example, an electric dust collector, a ceramic filter, etc.), and char (residual coal) and CaS are separated. The gas from which char and CaS have been separated is introduced into the topping combustor 18.

The char and CaS extracted from the bottom of the entrain desulfurization reactor 42 and the first dust removing device 44 are
The char distributor 46 divides into two systems. The char and CaS of one system are circulated to the partial gasification furnace 40, and the char and CaS of the other system are put into a pressurized circulating fluidized bed combustion furnace (char combustion furnace) 48 and pressurized from the air compressor 24. Combustion with air (for example, around 20 kg / cm ² G, around 400 ° C) at a temperature that allows dedusting without cooling
Ru to produce a certain 850 ° C. or less of the combustion gases. in this case,
The air ratio is set to about 5.5, for example, and the air is overburned to completely burn the char. And, since the air is over-exhausted up to the air ratio of 5.5 , the combustion gas is discharged from the second dust removing device 5 in the wake.
The temperature is lowered to an allowable temperature of 0 (for example, an electrostatic precipitator, a ceramic filter, etc.) (for example, around 850 ° C.). Then, this gas is introduced into the second dust removing device 50 to separate ash and gypsum (CaSO ₄ ), and then the topping combustor 1
8, the dedusted fuel gas produced in the partial gasification furnace 40 is burned in the dedusted combustion gas produced in the pressurized circulating fluidized bed combustion furnace 48. The combustion gas temperature becomes about 1300 ° C., for example, and is introduced into the gas turbine 20. Other configurations are similar to those in the case of FIG.

CaC is provided in the outlet gas passage of the partial gasification furnace 40.
O₃Or supplying fine powder of CaO, hydrogen sulfide in the gas,
Carbonyl sulfide etc. are removed. In this case, CaC
O _Three Alternatively, desulfurization with CaO is based on the following reaction. However
And H₂The case of S will be described. CaCO₃→ CaO + CO₂  CaO + H₂S → CaS + H₂O CaS is harmful and difficult to handle, but char burning
In the furnace 48, it is rendered harmless by the following oxidation reaction. CaS + 2O₂→ CaSO₄  Appropriate temperature for desulfurization with metal oxides such as Fe, Mn, and Zn
The temperature is about 400-700 ° C, but calcium oxide or
Calcium carbonate works best at 800-900 ° C
Therefore, the decrease in gas cooling efficiency for desulfurization is small.
Assuming the charging to the char combustion furnace 48, CaCO₃
Alternatively, the CaO particles are preferably fine powder. For this reason
Application of fixed bed or fluid bed desulfurization reactor is difficult
Therefore, the entrainment type is adopted. Ca
CO₃Or, make CaO particles into fine powder with a particle size of 5 μm or less
Thus, an effective desulfurization effect can be obtained with a contact time of 2 seconds or less.

Next, an experimental example will be described. The partial gasification gas was desulfurized under the following conditions. The results are shown in Table 1.
Shown in Temperature: 860 ° C., pressure: 10 atg, inlet H ₂ S concentration: 1500 ppm, absorbent: CaO, absorbent average particle size: 0.005 mm (5 μm), Ca / S molar ratio: 1
0

[0013]

[Table 1]

In the flow shown in FIG. 1, FIG. 2 shows an inlet temperature of the gas turbine 20 of 1300 ° C., an air ratio of the pressurized partial gasification furnace 40 of 0.5, and a steam pressure of the steam turbine 32 of 25.
The relationship between the partial gasification rate and the plant efficiency (transmission end) under the conditions of 6 kg / cm ² G and steam temperature of 538 ° C. is shown. In FIG. 2, PGCC represents the coal partial gasification combined cycle of the present invention, PFBC represents the pressurized fluidized bed cycle, GT represents the gas turbine, and IG.
CC shows the conventional coal gasification combined cycle shown in FIG. The PGCC system of the present invention shown in FIG. 1 showed the highest plant efficiency under the above conditions with a partial gasification rate of about 62%. Thus, the P of the present invention
In the GCC system, as shown in FIG.
Compared to the Ping cycle, the partial gasification rate is 50% or more
It shows high plant efficiency in the area.

[0015]

As described above, the present invention has the following effects. (1) Residual coal that was not gasified in the pressurized partial gasification furnace
Part (char) is pressurized circulating fluidized bed combustion furnace (char combustion furnace)
And it is completely burned by excess air combustion up to an air ratio of 5.5.
Temperature below 850 ° C, which is the temperature at which dust can be removed without cooling
Since the combustion gas is generated, the partial gasification rate is 50% or less.
High plant efficiency can be obtained in the upper area
It ( 2 ) Since only a part of the input coal is gasified in the partial gasification furnace, the amount of thermal bypass is also reduced compared to the conventional total gasification method, and the power generation efficiency of the system is increased. For example, when the gasification rate is about 60%, the thermal bypass amount, which was 20% in the past, is reduced to 12% (20% × 0.6). ( 3 ) Since the amount of air required for gasification also decreases,
Its compression power is reduced. As a result, the transmission end efficiency of the system is further increased. Therefore, conventional complete gasification I
Compared with GCC (Coal Gasification Combined Cycle),
Transmission end efficiency is improved by about 2% (when about 60% of input coal is gasified). ( 4 ) When the gasification rate is a part of the input coal and the char has a partial recycling system, the maximum efficiency point is always obtained for a wide range of coals from highly reactive coal to poorly reactive low quality coal. It is possible to drive with. ( 5 ) It is possible to desulfurize the gas without cooling the partial gasification furnace outlet gas, that is, without lowering the efficiency due to cooling, and eliminating the need for flue gas desulfurization in the downstream. For this reason, no special reactor or the like for desulfurization is required, and the apparatus is simplified. ( 6 ) CaS is detoxified by CaSO ₄ by introducing post-reaction and unreacted desulfurization agent particles into the char combustion furnace, and no post-treatment is required, and unreacted CaO is effectively used for desulfurization of char combustion furnace exhaust gas. To be done.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an embodiment of a coal partial gasification power generation device of the present invention.

FIG. 2 is a partial view of the partial coal gasification power generation method (line of PGCC marked with ◯) and the conventional pressurized fluidized bed topping cycle (line of PFBC topping cycle marked with Δ) in the apparatus of the present invention shown in FIG. 1. It is a graph which shows the relationship between a gasification rate and plant efficiency (transmission end).

FIG. 3 is a flow sheet showing an example of a conventional coal gasification power generation device.

[Explanation of symbols]

 10 pressurized complete gasification furnace 18 combustor 20 gas turbine 30 exhaust heat boiler 32 steam turbine 40 pressurized partial gasification furnace 42 air flow entrainment type (entrain) desulfurization reactor 44 first dedusting device 46 char distributor 48 addition Pressure circulating fluidized bed combustion furnace (char combustion furnace) 50 2nd dust removal device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Fujii, 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Akashi factory (72) Yukio Kubo 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy industry Co., Ltd. Akashi factory (72) Inventor Motoaki Hirao 2-4-1 Hamamatsucho, Minato-ku, Tokyo Kawasaki Heavy Industries, Ltd. Tokyo headquarters (72) Inventor Keisuke Kawamura 2-chome, Hamamatsucho, Minato-ku, Tokyo 4-1 Kawasaki Heavy Industries, Ltd. Tokyo head office (72) Inventor Seiya Ito 2-4-2-25 Minamisuna, Koto-ku, Tokyo Kawasaki Heavy Industries Ltd. Tokyo Design Office (72) Inventor Masahiro Uozumi 2 Minamisuna, Koto-ku, Tokyo 4th-25th Kawasaki Heavy Industries, Ltd. Tokyo Design Office (56) Reference JP-A-58-143129 (JP, A) JP-A-62-251428 (JP, ) Patent Akira 57-179290 (JP, A)

Claims (9)

(57) [Claims] 1. A combined cycle comprising a gas turbine (20) driven by a gas obtained by gasifying coal in a gasification furnace and a steam turbine (32) driven by steam overheated in the gasification furnace. In the power generation method, the following steps (a) to (d), that is, (a) a step of gasifying a part of the input coal in the partial gasification furnace (40), (b) a partial gasification furnace (40) in the remainder of the coal that has not gasified in a pressurized circulating fluidized bed combustion furnace (48), air ratio
Completely burned and cooled by excessive air combustion up to 5.5
Combustion gas below 850 ° C, which is the temperature at which dust can be removed without
Process of Ru to produce a, (c) pressurizing the circulating fluidized bed combustion furnace by mixing dilution air into the combustion gases (48), the downstream dedusting device (5
0) Process of lowering the combustion gas temperature to the allowable temperature, (d) Dedusting the gas generated in the partial gasification furnace (40), and then combusting in the degassed pressurized circulating fluidized bed combustion furnace (48) exhaust gas And a step of introducing the combustion gas into the gas turbine (20). 2. A partial gasification furnace (40) is recycled to the partial gasification furnace (40) with a part of the remainder of the coal that has not been gasified, so that the gasification rate is maximized to maximize system efficiency. It controls, The coal partial gasification power generation method of Claim 1 characterized by the above-mentioned. 3. Fine powder of calcium oxide or calcium carbonate is supplied to the outlet gas flow path of the partial gasification furnace (40),
Absorbs and removes hydrogen sulfide, carbonyl sulfide, etc. in the gas, collects the particles after sulfur absorption and unreacted particles in the dedusting device (44), and supplies them to the pressurized circulating fluidized bed combustion furnace (48). The partial coal gasification power generation method according to claim 1 or 2, characterized in that. 4. The coal partial gasification power generation method according to claim 3, wherein fine powder of calcium oxide or calcium carbonate having a particle diameter of 5 μm or less is used as the desulfurizing agent. 5. The flow path temperature between the charging part and the collecting part of the fine powder of calcium oxide or calcium carbonate is 1300 to 85.
5. The temperature is adjusted to a range of 0 ° C. 5.
The coal partial gasification power generation method described. 6. The gas flow path cross section downstream of the fine powder feeding section is enlarged so that the gas flow rate is 100 to 1000 of the final sedimentation velocity of the fine powder.
The coal partial gasification power generation method according to claim 3, 4 or 5, wherein the range is adjusted to 0 times. 7. A combined cycle comprising a gas turbine (20) driven by gas produced by gasifying coal in a gasification furnace and a steam turbine (32) driven by steam heated in the gasification furnace. In the power generator, the partial gasification furnace (40) that gasifies a part of the input coal and the remainder of the coal that was not gasified in the partial gasification furnace (40) are over-combusted to an air ratio of 5.5. 850 ° C or less, which is the temperature at which dust can be completely burned without cooling
Pressurized circulating fluidized bed combustion furnace Ru to produce a combustion gas (48)
And the first provided in the outlet gas flow path of the partial gasification furnace (40)
Dust remover (44), second dust remover (50) provided in the outlet gas flow path of the pressurized circulating fluidized bed combustion furnace (48), first dust remover (44) and second dust remover A combustor (18) provided on the downstream side of the device (50), and a coal partial gasification power generator. 8. A partial gasification furnace (40) is provided with a part of the remainder of the coal that has not been gasified in the partial gasification furnace (40).
The coal partial gasification power generator according to claim 7, further comprising a char distributor (46) for distributing the remainder to a pressurized circulating fluidized bed combustion furnace (48). 9. A gas flow passage between the partial gasification furnace (40) and the first dedusting device (44), wherein an air flow entrainment type desulfurization reactor (42) using fine powder of calcium oxide or calcium carbonate as a desulfurizing agent. ) Was provided, The coal partial gasification power generation device of Claim 7 or 8 characterized by the above-mentioned.