JPH0587315A - Power generation employing poor quality fuel - Google Patents

Abstract

PURPOSE:To utilize poor quality gas effectively by a method wherein a gas turbine is driven by combustion gas obtained by burning gas from a fluidized bed gasifying furnace, from which injurious constituents are removed, and gas from a fluidized bed oxydizing furnace while a steam turbine is driven by steam generated from the combustion gas respectively to effect power generation. CONSTITUTION:Gas 108, generated by burning poor quality fuel 101 in a fluidized bed gasifying furnace 1, is desulphurized and anmonia as well as cyanogen are decomposed. Unburnt constituents in solid residue are oxidized by oxygen containing gas in a fluidized oxidizing furnace 19, whose temperature is regulated so as to be 600-1000 deg.C by heat exchange between compressed gas 107, whereby gas 115 is obtained. Gas 108, 115 from both of the furnaces 1, 19 are supplied to a combustor 7 together with the compressed air 107, which has effected heat exchange in the fluidized bed oxidizing furnace 19 while gas 108 from the fluidized bed gasifying furnace 1 is burnt perfectly and, thereafter, drives a gas turbine 9 and generates steam 111 for driving a steam turbine 11 to effect power generation. According to this method. poor quality fuel can be utilized effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation method for converting chemical energy of poor fuel such as coal and heavy oil into electric energy.

[0002]

2. Description of the Related Art An example of a power generation method using coal will be described with reference to FIG. Coal 101 and water 103 containing an additive are mixed, pressurized from a normal pressure state by a pump 2, and supplied to the pressurized fluidized bed gasification furnace 1. The gasification pressure of the pressurized fluidized bed gasification furnace 1 is determined by the operating pressure of the gas turbine 9 in the wake,
It is usually set between 15 and 30 ata. In the pressurized fluidized bed gasification furnace 1, the char particles formed by gasifying coal are fluidized by the air 107b that is pressurized by the compressor 8 and supplied from below the furnace 1 to form the fluidized bed 22. To do. In the fluidized bed 22, thermal decomposition of coal 101, gasification reaction in which carbon of coal reacts with CO ₂ to generate CO, combustion reaction of air 107b supplied from the compressor 8 and coal 101, and air 107b and CO. Combustion reaction occurs.

In the pressurized fluidized bed gasification furnace 1, the temperature is 7
The temperature is set to 00 ° C. to 1000 ° C., and 40% or more of the carbon in the supplied coal 101 is converted into a gas to become a flammable generated gas 108, and the generated gas 108 is sent to the desulfurization furnace 3.

Gas generated from the fluidized bed gasification furnace 1 108
Is introduced into the desulfurization furnace 3 and comes into contact with the desulfurizing agent 102 and the recycle desulfurizing agent 106, so that H ₂ S,
COS reacts with the limestone in the desulfurizing agents 102 and 106 and is fixed in the desulfurizing agent as CaS. Further, the desulfurizing agent adsorbs V and alkali metals such as Na and K in coal, and prevents those components from being included in the generated gas.

After desulfurization in the desulfurization furnace 3, a combustible gas 10 is generated.
8a is sent to the cyclone 4a, the coal char and the desulfurizing agent particles contained in the generated gas 108a are removed by the cyclone 4a, and then enters the ceramics filter 5a. The particles 116 such as the desulfurizing agent recovered by the cyclone 4a are sent to a fluidized bed oxidation furnace 19 described later.

Particles 117 such as a desulfurizing agent in the generated gas 108a collected by the ceramics filter 5a are sent to a fluidized bed oxidation furnace 19 described later.

Fluidized bed 22 in the pressurized fluidized bed gasification furnace 3
In order to maintain a constant bed height of the coal char particles 112,
It is sent from the pressurized fluidized bed gasification furnace 3 to a fluidized bed oxidation furnace 19 described later.

If it passes through the ceramics filter 5a
Combustible gas 108b with extremely low dust content
At the compressor 8 in the ammonia decomposition tower 6
Generated gas 1 due to partial combustion by pressurized air 107e
08b temperature is increased to 900 ℃ ~ 1200 ℃,
Containing nickel placed in the ammonia decomposition tower 6
In the generated gas 108b by passing through the catalyst
Ammonia (NH ₃) And HCN etc. as nitrogen (N₂) To
Disassemble. The temperature of the generated gas 108b is included in the generated gas.
H₂It is determined by the durability of S and the catalyst. The above
The generated gas 108b is supplied from the ammonia decomposition tower 6 to the
To the compressor 7 and the compressor 7
Air 107c pressurized by sir 8 and fluidized bed oxidation described below
Complete combustion by the combustion gas 115a of the furnace
The temperature of 9 becomes 1250 ℃ ~ 1500 ℃, gas turbine
9 is introduced. Combustion gas 109 is fed to gas turbine 9
Give it energy and rotate it,
It is converted into electricity by the generator 17.

The combustion gas 109a, which has passed through the gas turbine 9 and has been depressurized to near normal pressure, is introduced into the exhaust heat recovery boiler 10. In the exhaust heat recovery boiler 10, the sensible heat of the combustion gas 109 a is transferred to the water 110 in the heat exchanger 21. The water 110 is heated in the heat exchanger 21 and evaporated to become steam 111. The energy received by the steam 111 is given to the steam turbine 11 to rotate it,
The steam turbine drives the generator 18 and is ultimately converted into electricity.

Steam 111 leaving the steam turbine 11
Is condensed by the condenser 12, pressurized by the pressure pump 13, and then sent to the heat exchanger 21 again.

In the fluidized bed oxidation furnace 19, the fluidized bed 27 is fluidized by the air 107a introduced from the compressor 8, and the coal char sent from the pressurized fluidized bed gasification furnace 1 as described above. 112, the desulfurizing agent 120 sent from the desulfurization furnace 3, the dusts 116 and 117 sent from the cyclone 4a and the ceramics filter 5a,
In the fluidized bed 27, CaS is oxidized to CaSO ₄ and unburned components are burned.

In order to change CaS to CaSO ₄ ,
The temperature in the fluidized bed oxidation furnace 19 is 600 ° C. to 1000 ° C.,
Desirably, 700 ° C to 1000 ° C is selected. Desulfurizing agent particles 113 extracted from the bottom of the fluidized bed oxidation furnace 19
Is separated through the lock hoppers 15a and 16a.
The coarse particles having a high CaCO ₃ and CaO content in the separator 20 are discharged to the pulverizer 23 as the recycle desulfurization agent 106c, and the remaining fine powder particles are discharged to the outside of the system as the discharged ash 106a. The recycled desulfurization agent 106c pulverized into fine powder particles by the pulverizer 23 is returned to the desulfurization furnace 3 as a part of the desulfurization agent. Further, the combustion gas 115 generated in the fluidized bed oxidation furnace 19 enters the cyclone 4b to separate the ash and the desulfurizing agent, and the separated ash and the desulfurizing agent 118 is sent to the hopper 15b.

On the other hand, the combustion gas 115 from which the ash and the desulfurization agent 118 have been separated is introduced into the ceramics filter 5b, where the combustion gas 1 in which the desulfurization agent and the ash are further separated.
15a is introduced into the combustor 7 as described above.
Further, the ash and the desulfurizing agent 119 collected by the ceramics filter 5b are sent to the lock hopper 15b, and are discharged out of the system as the discharged ash 106b through the lock hopper 16b together with the ash and the desulfurizing agent 118.

The combustion exhaust gas 109b which has passed through the exhaust heat recovery boiler 10 is diffused into the atmosphere by the chimney 14. As described above, the combustion exhaust gas 109b is desulfurized in the pressurized fluidized bed gasification furnace 1 and alkali metals such as Na and K and V are removed, and ammonia (NH ₃ ) in the ammonia decomposition tower 6 HCN and the like are decomposed into nitrogen, whereby the NO _x content in the combustion exhaust gas 109b is small and the purified gas is discharged from the chimney to the atmosphere.

The compressor 8 is directly connected to the gas turbine 9 and driven, and sucks the air 103 and compresses the air 103 to a high pressure, and pressurizes the compressed air 107. The air 107a, 107
b, the air 107c and 107d which are respectively sent to the fluidized bed oxidation furnace 19 and the pressurized fluidized bed gasification furnace 3 and pressurized.
Is sent to the ammonia absorption tower 6 and the combustor 7.

[0016]

In the power generation method shown in FIG. 2, the amount of the combustion gas 115 generated from the fluidized bed oxidation furnace 19 is large, and the fluidized bed oxidation furnace 19, the ceramic filter 5b and the cyclone 4b are large. There was a drawback.

The present invention is intended to provide a power generation method using poor fuel which can solve the above problems.

[0018]

In the power generation method using bad fuel of the present invention, the bad fuel is supplied to a fluidized bed gasifier, and at least 40% of carbon in the bad fuel is gasted in the fluidized bed gasifier. After converting to, the gas generated in the fluidized bed gasification furnace is desulfurized with limestone, and then contacted with a catalyst containing nickel to decompose ammonia and cyan in the generated gas, and in the fluidized bed gasification furnace. The produced solid residue is transferred to a fluidized bed oxidation furnace to which an oxygen-containing gas is supplied, and the solid residue and the oxygen-containing gas are heat-exchanged with compressed air in the fluidized bed oxidation furnace to obtain a temperature of 600 ° C. The solid residue is oxidized while controlling the temperature in the range of 1000 ° C. to generate a gas, and the gas generated in the fluidized bed gasification furnace and the fluidized bed oxidation furnace in which the desulfurization and the decomposition of ammonia and cyan are performed. Gas Generation and Fluidized Bed Oxidation With the compressed air that has undergone heat exchange in a combustor as a combustion gas, the combustion gas is used to drive a gas turbine, and the steam generated by the combustion gas that has exited the gas turbine is used to drive a steam turbine, The gas turbine and the steam turbine rotate a generator to generate electricity.

[0019]

In the present invention, the bad fuel is burned in the fluidized bed gasification furnace, and 40% or more of carbon contained in the bad fuel is converted into gas at a high conversion rate. This generated gas is
It is desulfurized by limestone, and the ammonia and cyan contained therein are decomposed by the catalyst containing nickel. On the other hand, the fixed residue produced in the fluidized bed gasification furnace is subjected to heat exchange with compressed air to oxidize unburned components by the oxygen-containing gas in the fluidized bed oxidation furnace whose temperature is adjusted to the range of 600 ° C to 1000 ° C. Generated gas.

The gas generated in the fluidized bed gasification furnace, which is desulfurized and decomposed into ammonia and cyan, and the gas generated in the fluidized bed oxidation furnace, are converted into a combustor together with compressed air which has been heat-exchanged in the fluidized bed oxidation furnace. When supplied, the generated gas of the fluidized bed gasification furnace is completely combusted, and also generates steam that drives the gas turbine and the steam turbine,
Power is generated.

The gas supplied to the gas turbine is desulfurized as described above, the contained ammonia and cyanide are decomposed, and the gas is completely burned by the combustor, so that it is in a sufficiently purified state. The adverse effects on the gas turbine and the equipment on the downstream side are prevented, and the gas discharged to the outside of the system is also cleaned.

In particular, in the present invention, in the fluidized bed oxidation furnace, heat exchange is performed by compressed air, whereby
Since the temperatures of the solid residue and the oxygen-containing gas in the fluidized bed gasification furnace are maintained at the required 600 ° C to 1000 ° C, it is sufficient to supply the oxygen-containing gas required for combustion to the fluidized bed oxidation furnace. Therefore, the amount of combustion gas generated in the fluidized bed oxidation furnace is reduced, and accordingly, the fluidized bed oxidation furnace and the ceramic filters, cyclones, and the like attached thereto are downsized.

Further, the compressed air, which has been heated in the fluidized bed gasification furnace to raise its temperature, is supplied to the combustor and burned, whereby the heat is recovered and the thermal efficiency is improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
In this embodiment, in the conventional power generation method using coal shown in FIG. 2, compressed air 107d supplied from the compressor 8 to the combustor 7 and the ammonia decomposition tower 6 is heat-exchanged in a fluidized bed oxidation furnace 19. Part of the compressed air leaving the heat exchanger 28 107e
Was supplied to the ammonia decomposition tower 6, and the balance 107c was supplied to the combustor 7. This compressed air 10
The flow rate of 7d is controlled by a flow control valve 29 provided between the inlet side and the outlet side of the compressed air in the heat exchanger 28,
The amount of compressed air 107e to be supplied to the ammonia decomposition tower 6 and compressed air 107c to be supplied to the combustor 7 by short-passing the compressed air without passing through the heat exchange 28 is adjusted by adjusting the opening degree of the same flow regulating valve 29. You can do it.
The heat transfer tube of the heat exchanger 28 uses a rifle tube or a ribbon tube to improve the internal heat transfer coefficient.

Since the configuration, operation, effects, etc. of the other parts of the device of this embodiment are the same as those of the power generation method shown in FIG. 2, the corresponding devices in FIG. 1 are the same as those in FIG. The reference numerals are given and the description thereof is omitted.

In the present embodiment, in the fluidized bed oxidation furnace 19, the heat exchanger 28 to which compressed air 107d is supplied.
Is heat-exchanged, and the coal char particles 112 of the pressurized fluidized bed gasification furnace 1 supplied into the furnace 19, the desulfurization agent 120 supplied from the desulfurization furnace 3, the cyclone 4a and the ceramic filter 5a are supplied. With the temperature of the dusts 116 and 117 and the compressed air 107a adjusted in the range of 600 ° C. to 1000 ° C., unburned components are burned in the fluidized bed 27 and CaS is oxidized to CaSO ₄ . Done.

The combustion gas generated in the fluidized bed oxidation furnace 19 is
It is purified by the cyclone 4b and the ceramics filter 5b and supplied to the combustor 7. As described above, in the fluidized bed oxidation furnace 19, the temperature inside the furnace is required to be 600 due to the heat exchanger to which the compressed air 107d is supplied. ℃ ~ 100
Since it is adjusted to the range of 0 ° C, the fluidized bed oxidation furnace 19
The amount of compressed air 107a supplied to the furnace is sufficient to burn the unburned components in the furnace 19 and oxidize CaS to CaSO ₄ . Therefore, the amount of combustion gas 115 generated in the furnace 19 is reduced, and the furnace 19 and the cyclone 4b and the ceramics filter 5b on the downstream side can be downsized.

Further, the compressed air 107c and 107e heated by heat exchange in the heat exchanger 28 of the fluidized bed oxidation furnace 19 are heated.
Are supplied to the combustor 7 and the ammonia decomposing tower 6, respectively, and heat is recovered, so that the thermal efficiency can be improved.

In the conventional power generation method shown in FIG. 2, when the fluidized bed oxidation furnace 19 was operated at 900 ° C., the amount of combustion gas 115 generated per 1 kg of coal was 12.6 kg. On the other hand, as in the present embodiment, when the heat exchanger 28 is installed and the compressed air 107d is heat-exchanged from the heat exchanger inlet temperature 400 ° C. to the outlet temperature 600 ° C., the combustion gas 115
It was possible to reduce the generation amount of urine to 8.6 kg. Therefore, the size of the ceramics filter 5b can be reduced to 68%.

In addition, the following effects were also produced. Conventionally, in case of partial load, fluidized bed oxidation furnace 19
The gas flow rate of No. 1 was decreased according to the load. However, in the present embodiment, the flow rate ratio of the compressed air 107a to the coal is reduced by reducing the flow rate ratio of the compressed air 107d to the coal at the partial load as compared with the flow rate ratio of the compressed air 107d to the coal at 100% load. It has become possible to suppress the decrease in the gas flow velocity of the fluidized bed oxidation furnace 19 to a smaller rate than in the past. This enables stable operation of the fluidized bed oxidation furnace 19 even under partial load.

[0031]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the solid residue produced in the fluidized bed gasification furnace for gasifying poor fuel is transferred to the fluidized bed oxidation furnace by heat exchange with compressed air. By adjusting the temperature to 600 ° C. to 1000 ° C., the amount of gas generated in the fluidized bed oxidation furnace is reduced, and along with this, the fluidized bed oxidation furnace and cyclones attached to the same, ceramic filters, etc. Can be miniaturized.

The compressed air, which has been heated by performing heat exchange in the fluidized bed oxidation furnace, is supplied to the combustor together with the gas generated in the fluidized bed gasification furnace and the combustion gas in the fluidized bed oxidation furnace.
The heat is recovered and the thermal efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a system diagram of an example of a conventional power generation method using coal as poor fuel.

[Explanation of symbols]

1 Pressurized fluidized bed gasifier 2 Pump 3 Desulfurization furnace 4, 4a, 4b Cyclone 5, 5a, 5b Ceramics filter 6 Ammonia decomposition tower 7 Combustor 8 Compressor 9 Gas turbine 10 Exhaust heat recovery boiler 11 Steam turbine 12 Condenser 13 Addition Pressure pump 14 Chimneys 15a, 15b, 15c, 15d, 16a, 16b, 1
6c, 16d Hopper 17, 18 Generator 19 Fluidized bed oxidation furnace 20 Separator 21 Heat exchanger 22 Fluidized bed 23 Crusher 24 Heat exchanger 25 Gasification furnace 26 Desulfurization device 27 Fluidized bed 28 Heat exchanger 29 Flow control valve 101 Fuel 102 Desulfurizing agent 103 Water 105 Exhaust ash 106 Fine powder desulfurizing agent 106a, 106b Exhaust ash 106c Coarse powder desulfurizing agent 107, 107a, 107b, 107c, 107d, 1
07e Pressurized air 108,108a, 108b Generation gas 109,109a, 109b Combustion gas 111 Steam 112 Coal char 115,115a Fluidized bed oxidation furnace combustion gas 116,117 Dust 120 Desulfurizing agent

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumiya Nakajima Inventor, Fumiya Nakajima 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1. A gas generated in the fluidized bed gasification furnace after supplying poor fuel to the fluidized bed gasification furnace and converting 40% or more of carbon in the bad fuel into gas in the fluidized bed gasification furnace. Is desulfurized with limestone, and then it is contacted with a catalyst containing nickel to decompose ammonia and cyan in the generated gas, and the solid residue produced in the fluidized bed gasification furnace is supplied with oxygen-containing gas. The solid residue is transferred to a bed oxidation furnace, and the solid residue and the oxygen-containing gas are heat-exchanged with compressed air in the fluidized bed oxidation furnace to adjust the temperature in the range of 600 ° C to 1000 ° C to remove the solid residue. Oxidation to generate gas, the desulfurization and decomposition of ammonia and cyanide, the gas generated in the fluidized bed gasification furnace, the gas generated in the fluidized bed oxidation furnace, and the heat exchange performed in the fluidized bed oxidation furnace Combustor with compressed air To generate combustion gas, drive the gas turbine with the combustion gas, drive the steam turbine with the steam generated by the combustion gas exiting the gas turbine, and rotate the generator with the gas turbine and the steam turbine. A power generation method using poor fuel, which is characterized by performing the power generation by