JPH06264073A - Coal gasifier - Google Patents

Abstract

PURPOSE:To provide a coal gasifier whereby the chemical energy of coal can be effectively utilized and the concentration of sulfur components in the formed gas can be lowered. CONSTITUTION:A formed gas 700a leaving a coal gasifier 1 is led to a desulfurization oven 2 in which a fluidized bed of limestone is formed. The inside of the oven 2 is divided into upper and lower fluidized layers 2B and 2A with an inside dispersing plate 22. The char 101 from the oven 1 passes hoppers 7a to 74a, is elevated in pressure and is fed to an oxidation oven 3. The CaS, etc., also leaving the oven 2 pass hoppers 70b to 74b, are elevated in pressure, and are fed to the oven 3. In the oven 3, the heat generated by the oxidation of the char 101 and the CaS, etc., 401 with air 201 and steam 300 is recovered with a heat exchanger 4 in the oven 3. The combustion gas from the oven 3 is led through a cyclone 6 to the gasifier 1. In the Fig., 10a, 10b, 10c and 10d are flow rate control means in which inert gas is utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for gasifying coal to obtain coal gasification gas.

[0002]

2. Description of the Related Art Coal is still important as a fuel for power generation because of its large reserves and uneven distribution of reserves worldwide, but SO _X , NO _X , CO from coal power plants ₂
It is necessary to reduce the emission of substances that adversely affect the global environment such as the above and improve the power generation efficiency. For this reason, coal gasification power generators and pressurized fluidized bed combustion boiler power generators have been developed that replace conventional pulverized coal boilers. One of the power generators under development is a power generator using a fluidized bed coal gasification furnace. A conventional example is shown in FIG.

This conventional example is a fluidized bed coal gasification furnace which the present inventors have developed. The development is reported on pages 1 to 7 of Mitsubishi Heavy Industries Technical Report Vol.22 No.3. A conventional example will be described with reference to FIG. Coal 100 and coal carrier air 200 are supplied to the coal gasifier 1.
In the coal gasification furnace 1, coal and char become fluidized particles of the fluidized bed 1A, which are fluidized by the gasification gas 700d of the lower gasification furnace 9 and the coal carrier air 200 which are introduced through the gas dispersion plate 11. The layer 1A is formed. 100 coal is gasified in the fluidized bed 1A.

Gasification gas 70 generated from the coal gasification furnace 1
Cyclone 5 removes dust from 0a. The gasified gas 700b after dedusting is sent to a gas purification device (not shown) in the downstream. Char 101 not gasified in coal gasifier 1
Is extracted from the coal gasifier 1 and the char transfer device 76
Be transferred to. Char 10 recovered by Cyclone 5
2 is transferred to the char transfer device 77.

By the char transfer device 76, the char 101 is supplied to the lower gasification furnace 9 by the action of gravity and the inert gas 500e. The char transfer device 77 allows the char 102 to move to the air.
The gas is conveyed to 203 and supplied to the lower gasification furnace 9. In the lower gasification furnace 9, air 201 and steam 300 are distributed on the gas dispersion plate.
Supplied through 31. With air 201 and steam 300,
The char is fluidized, the char is gasified in the fluidized bed 9A, and is converted into combustible gasified gas 700d and exhaust ash 901.

The first problem of the prior art described above is that
The utilization efficiency of the chemical energy of coal is low. Of the chemical energy of coal, the unburned char 901 discharged to the outside of the system without being gasified in the coal gasification furnace 1 and the lower gasification furnace 9 and the coal gasification gas 700b and taken out of the system The carbon content was high. The second problem of the conventional technology is that the coal gasification gas 700b is used for desulfurization.
It is necessary to lower the temperature of, and this temperature reduction resulted in energy loss.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a highly efficient coal gasifier which efficiently converts the chemical energy of coal into sensible heat of gas so that it can be used in a thermal power plant. The task is to do. Another object of the present invention is to provide a coal gasification furnace that emits a small amount of SO _X , NO _X , CO ₂ , and the like. Furthermore, the present invention effectively divides a desulfurizer into which coal gasification gas leaving the coal gasification furnace is divided into upper and lower fluidized beds, and controls each fluidized bed under optimum conditions to effectively remove sulfur compounds in the coal gasification gas. It is also an object to provide a coal gasification device that can be fixed to the.

[0008]

[Means for Solving the Problems]

(Reduction of unburned carbon) In the coal gasifier according to the present invention,
The char is supplied from the coal gasification furnace to oxidize the unburned components in the char, and the desulfurization agent is supplied from the desulfurization furnace to convert CaS in the desulfurization agent to CaSO ₄ and heat generated by these oxidation reactions. Is equipped with a heat exchanger that heats the fluid, and an oxidation furnace that supplies combustion gas to the coal gasification furnace as combustion gas is provided. In this oxidation furnace, in order to reduce unburned carbon, a heat exchanger is installed in the furnace so that it can be operated at an air ratio of 1 or more, the temperature of the fluidized bed is softened by fluidized bed particles, and the particles adhere to each other. The char generated in the gasification furnace is burned and the energy held by the char is effectively recovered while controlling the temperature below the temperature at which the granulation by the above does not occur.

(Desulfurization of Gasified Gas without Cooling) In the coal gasifier according to the present invention, limestone is used as a desulfurizing agent so that the desulfurization of the gasified gas can be performed without significantly lowering the temperature of the coal gasified gas. A desulfurization furnace is installed downstream of the coal gasification furnace. That is, in the coal gasifier according to the present invention, limestone is supplied and the limestone is used as particles for fluidization, and coal gasification gas supplied from the gasification furnace is used as gas for fluidization to form a fluidized bed. A desulfurization furnace is installed to fix the sulfur compounds in the coal gasification gas as CaS.

Furthermore, the coal gasifier according to the present invention also employs a desulfurization furnace having the following structure. That is, as a desulfurization furnace, a gas dispersion plate that forms a fluidized bed of limestone, and the movement of particles in the fluidized bed that is arranged in the fluidized bed is restricted and the fluidized bed is divided into an upper fluidized bed and a lower fluidized bed. A heat exchanger is provided in the upper fluidized bed to keep the temperature of the upper fluidized bed at 800 ° to 900 ° C and the limestone is supplied to the lower fluidized bed. The coal gasification gas is supplied from the coal gasification furnace through the gas dispersion plate to maintain the temperature of the lower fluidized bed at 900 ° to 1000 ° C.

[0011]

[Action]

(Reduction of unburned carbon) In the coal gasification apparatus according to the present invention, the oxidation furnace is installed as described above, and the char that comes out of the coal gasification furnace is burned by using this oxidation furnace as an oxidizing atmosphere to generate coal gasification. It becomes possible to completely convert the unburned components in the char generated in the furnace into gas, and the unburned components taken out of the system along with the coal gasification gas and the ash extracted from the lower part of this oxidation furnace. It has become possible to make the concentration of unburned components inside extremely small.

(Desulfurization of gasified gas without cooling) with limestone
The reaction of H ₂ S and COS can improve the reaction rate from limestone to CaS by simultaneously causing the calcination reaction in which CO ₂ escapes from limestone. When coal gasification gas is used for gas turbine combined power generation, the pressure of the gasification furnace is selected to be 10 to 30 Kg / cm ² , and the desulfurization temperature in such a case is 900 to 1050.
℃ is suitable. This temperature is almost the same as the operating temperature of the fluidized bed coal gasification furnace, and it is possible to desulfurize the gasification gas by introducing the coal gasification gas into the desulfurization furnace without cooling. In the coal gasifier according to the present invention, the desulfurization furnace using the fluidized bed of limestone is used as described above, the residence time of limestone can be adjusted by adjusting the fluidized bed height of limestone, and limestone is It is possible to secure a residence time for any limestone that completes the reaction of converting to CaS.

According to the present invention, the fluidized bed in the desulfurization furnace is divided into upper and lower tiers by the internal dispersion plate, and a heat exchanger is arranged in the upper fluidized tier to keep the limestone at 800 ° -900 ° C. It is supplied to the lower fluidized bed from the coal gasification furnace through the gas distribution plate, and the gas is supplied from 900 ° to 1000 ° C.
In the upper fluidized bed, the unreacted limestone and H ₂ S,
COS reacts and H ₂ S and COS in the gas are fixed on the limestone surface.

The particles of limestone whose surface became CaS move to the lower fluidized bed, the fluidized bed temperature reaches 900 to 1000 ° C., and the reaction of CaSO ₃ in limestone to decompose into CaO and CO ₂ occurs, and the inside of the limestone particle When CO ₂ is released from limestone, the effective reaction area of limestone increases, and H ₂ S and COS are fixed as CaS inside limestone. By setting the temperature of the lower fluidized bed to 900-1000 ° C, the reaction rate of CaCO ₃ to CaO and CO ₂ and the desulfurization reaction rate can be made almost equal, and the CaS production weight per limestone weight can be set. Can be increased. above
Since the reaction rate at which CaCO ₃ becomes CaO and CO ₂ is affected by the CO ₂ partial pressure, the reaction rate at which CaCO ₃ becomes CaO and CO ₂ can be finely adjusted depending on the temperature.

In the lower fluidized bed, the concentrations of H ₂ S and COS in the gasified gas decrease, but from the reaction equilibrium of limestone and H ₂ S, as shown in FIG. The H ₂ S concentration is high. H ₂ S in gas on reaction equilibrium in lower fluidized bed
After reaching a value close to the concentration, it is possible to further reduce the H ₂ S concentration by reacting unreacted limestone in the upper fluidized bed with a temperature lower than that in the lower fluidized bed.

(Improvement of power generation efficiency) When the gasification gas generated by the coal gasifier according to the present invention is used for a gas turbine combined cycle power generator, the inside of the oxidation furnace used in the coal gasifier according to the present invention As the fluid to be supplied to the heat exchanger installed in the
A case is possible. That is, when steam is supplied to the heat exchanger of the oxidation furnace and the steam turbine is driven by the steam to generate electric power, and when compressed air generated from the air compressor is supplied to the heat exchanger of the oxidation furnace. It is a case where the power generation output of the gas turbine is increased by increasing the temperature of the gas, supplying the compressed air to the gas combustor of the gas turbine and supplying the combustion gas to the gas turbine. In either case, It becomes possible to improve power generation efficiency.

(Improvement of Desulfurization Rate (Desulfurization of Oxidation Furnace Gas)) In the oxidation furnace used in the coal gasifier according to the present invention, CaS from the desulfurization furnace is reacted with O ₂ to form CaSO _4. Occurs.

[0018]

[Equation 1]

The following reaction occurs as the side reaction.

[0020]

[Equation 2]

SO ₂ generated by the above reaction (2) is
By reacting with CaO in the fluidized bed of the oxidation furnace, Ca
It is fixed as SO ₄ , but there is no chance of contact with CaO. SO ₂ in the combustion gas from this oxidation furnace to the coal gasifier
However, SO ₂ is converted to H ₂ S in the coal gasification furnace and fixed as CaS in limestone.

[0022]

EXAMPLE A coal gasifier according to the present invention will be specifically described below based on an example shown in FIG. 100 coal and 200 compressed air are supplied to the coal gasifier 1. In the coal gasification furnace 1, coal 100 is introduced through oxygen in the compressed air 200 and the gasification furnace dispersion plate 11 and combustion gas 600d of the oxidation furnace 3
It is gasified by and converted into the gasified gas 700a and the char 101.

The particle flow rate adjusting unit 10a is supplied with the inert gas 500a in the pipe. The inert gas 500a is intermittently supplied, and when the inert gas 500a is supplied, the particles in the pipe are fluidized, and when the inert gas 500a is not supplied, it becomes a fixed bed. When the particles are fluidized, the particles are transferred from the gasification furnace 1 to the hopper 70a. Char 101
Controls the discharge amount by controlling the supply amount of the inert gas 500a and the time for which the inert gas 500a is interrupted, and controls the discharge amount to the hopper 70a.

The gasification gas 700a is dedusted by the cyclone 5. The particles dedusted by the cyclone 5 are passed through the particle flow rate adjusting unit 10b and the inert gas 500b is used to remove the particles in the cyclone 5.
Recycle from the bottom to the inside of fluidized bed 1A. The gasified gas 700b after dedusting is supplied to the desulfurization furnace 2 through the dispersion plate 21.
A fluidized bed of limestone 400 is formed in the desulfurization furnace 2, and the gasification gas 700b serves as the fluidized gas of the fluidized bed.

The desulfurization furnace 2 is divided into an upper fluidized bed 2B and a lower fluidized bed 2A by an internal dispersion plate 22. Limestone 400 is supplied to the upper fluidized bed 2B. The internal dispersion plate 22 has the cross-sectional area of the fluidized bed limited to 50% or less only in that portion, and the upper fluidized bed is
2B and lower fluidized bed 2A are limited in particle mixing. A cooler 23 is installed in the upper fluidized bed 2B, by which particles and gas are cooled, and by controlling the mixing amount of the particles of the upper fluidized bed 2B of the internal dispersion plate 22 and the particles of the lower fluidized bed 2A, Upper fluidized bed
2B temperature is 800-900 ℃, lower fluidized bed 2A temperature is 950
Kept at ℃. Limestone 400 and H ₂ S in gasification gas 700b
COS reacts and part of limestone 400 is converted to CaS.
The desulfurized gasified gas 700c is sent to a dust removing device (not shown).

The desulfurization agent 401 extracted from the desulfurization furnace 2 is extracted while the amount of extraction is adjusted by the particle flow rate adjusting unit 10c using the inert gas 500c. The char 101 produced in the coal gasifier 1 is received by the hopper 70a, and if the hopper 72a is being pressurized, the char 101 is stored in the hopper 70a until the pressure of the hopper 72a becomes the same as that of the hopper 70a. When the hopper 70a and the hopper 72a have the same pressure, the valve 71a is opened and the char 101 drops to the hopper 72a. Next, the valve 71a is closed, the hopper 72a is pressurized, and when the pressure becomes the same as that of the hopper 74a, the valve 73a is opened and the char 101 drops into the hopper 74a. The char 101 in the hopper 74a is connected to the oxidizing furnace 3 by the rotary feeder 75a.
Is supplied in a fixed amount.

The limestone containing CaS produced in the desulfurization furnace 2 is
Similar to the char 101, the hoppers 70b, 72b, 74b, the valves 71b, 73b and the rotary feeder 75b are used to supply the oxidizing furnace 3. In the oxidation furnace 3, a fluidized bed is formed mainly by the desulfurizing agent. The particles 402 are collected by the char 101, the limestone 401, and the cyclone 6, and the particles 402 are supplied to the fluidized bed 3A through the particle flow rate adjusting unit 10d using the inert gas 500d. The fluidized bed 3A is fluidized by the air 201 and the steam 300 supplied from the furnace bottom through the dispersion plate 31. In the fluidized bed 3A, char is rapidly converted into gas and ash by the combustion reaction, whereas CaS in limestone is slowly converted.
Since it is converted to CaSO ₄ , the fluidized particles in the fluidized bed 3A mainly contain the desulfurizing agent.

A fluid 202 flows through the freeboard of the oxidation furnace 3.
A heat exchanger 4 is installed and rises from the fluidized bed 3A.
Of the fluidized bed 3A by absorbing the heat of particles and gas
Temperature CaS and CaSO_FourThe reaction that occurs occurs as a side reaction
SO₂Reacts with CaO to cause CaSO _FourThe reaction to
At a temperature at which the ash and desulfurization agent do not soften and agglomeration does not occur.
It is controlled within the range of 850-1050 ℃. From the oxidation furnace 3
Two pipes are connected to Icron 6, one of which is
A position near the top of the oxidation furnace 3, that is, near the top of the heat exchanger 4
And the other is piped from the same height as the bottom of the heat exchanger 4.
Is installed. This attaches to one of the pipes
Cyclone is applied from the top of the heat exchanger 4 by the valve 8 provided.
Combustion gas 600a transferred to the heat exchanger 6 and the heat from the bottom of the heat exchanger 4
Adjusting the amount of combustion gas 600b transferred to Icron 6.
Control the temperature of the combustion gas 600d supplied to the gasification furnace 1.
This is to adjust. Combustion gas from the oxidation furnace 3 is combined
It becomes 600c and flows to cyclone 6.

Ash in coal and limestone after desulfurization are discharged from the bottom of the oxidation furnace 3 as discharged ash 900 or as discharged ash 901 from the lower part of the cyclone 6 to the outside of the apparatus.
The present invention has been specifically described above based on the illustrated embodiments, but the present invention is not limited to these embodiments, and within the scope of the present invention set forth in the claims, various shapes and structures can be used. It goes without saying that changes may be made.

[0030]

In the coal gasifier according to the present invention, the char is supplied from the gasification furnace to oxidize the unburned components in the char, and the desulfurization agent is supplied from the desulfurization furnace to supply CaS in the desulfurization agent. To CaSO ₄ , and equipped with a heat exchanger that heats the fluid with the heat generated by these oxidation reactions, since an oxidation furnace that supplies combustion gas to the gasification furnace as the combustion gas is used, coal gasification The chemical energy of coal such as char discharged from the furnace can be sufficiently recovered by the heat exchanger. For example, the coal gasifier in the coal gasifier of the present invention is used as a coal gasifier for gas turbine combined cycle power generation, pressurized air is supplied to the heat exchanger of the oxidation furnace, and the pressurized air is used in the gas turbine. A coal gasification gas turbine combined cycle power generator capable of converting all the chemical energy of coal into sensible heat of the gas to be supplied to the gas turbine by being configured to be supplied to the gas combustor of It becomes possible to perform high-efficiency power generation.

Further, in the coal gasifier according to the present invention,
The limestone is supplied and the limestone is used as fluidizing particles and the coal gasification gas supplied from the gasification furnace is used as the fluidizing gas to form a fluidized bed to remove the sulfur compounds in the coal gasification gas.
Since the desulfurization furnace that fixes as CaS is adopted, the coal gasification gas generated by the coal gasification furnace is passed through the fluidized bed of limestone in this desulfurization furnace to generate H ₂ S in the gasification gas.
It is possible to reduce the sum of COS concentrations to the chemical equilibrium concentration of the following formula.

[0032]

[Equation 3]

The relationship between the chemical equilibrium concentration of H ₂ S and the water vapor concentration in the above reaction is as shown in FIG. In addition to the above, according to the present invention, an internal dispersion plate is arranged in the fluidized bed of the desulfurization furnace to limit the movement of particles in the fluidized bed to divide the fluidized bed into an upper fluidized bed and a lower fluidized bed. A heat exchanger is installed in the upper fluidized bed to keep the temperature at 800 ° C to 900 ° C, and the lower fluidized bed is supplied with coal gasification gas from the coal gasification furnace to 900 ° C to 10 ° C.
If the temperature is kept at 00 ° C, the sulfur compounds in the coal gasification gas can be effectively fixed and removed as CaS.

The system configuration of the present invention is as described above.
SO generated in the oxidation furnace ₂To reduce the concentration
It becomes possible and H of coal gasification gas mentioned above₂Low S concentration
It is possible to reduce. As described above, the present invention is economical and
One, SO_X, NO_X, CO₂Efficient coal gas with low emissions
It is possible to provide a soot converting device.

[Brief description of drawings]

FIG. 1 is an equipment layout diagram showing a configuration of a coal gasifier according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the H ₂ S concentration after desulfurization and the water concentration in the gasification gas.

FIG. 3 is an equipment layout diagram showing a conventional fluidized bed coal gasification furnace.

[Explanation of symbols]

1 Gasification Furnace 1A Gasification Furnace Fluidized Bed 11 Gasification Furnace Dispersion Plate 100 Coal 101 Char 10a Gas Flow Furnace Char Particle Flow Rate Control Unit 10b Cyclone Char Particle Flow Rate Control Unit 10c Desulfurizing Agent Particle Flow Rate Control Unit 2 Desulfurization Furnace 2A Lower fluidized bed of desulfurization furnace 2B Upper fluidized bed of desulfurization furnace 21 Desulfurization furnace dispersion plate 22 Internal dispersion plate 23 Heat exchanger 200, 201 Air 202 Fluid (air or steam) 203 Air 3 Oxidation furnace 3A Oxidation furnace fluidized bed 300 Steam 31 Dispersion plate 4 Heat exchanger 400 Limestone 401 Limestone reacted in desulfurization furnace 5 Gasifier cyclone 6 Oxidation cyclone 500a, 500b, 500c, 500d Inert gas 600a, 600b, 600c, 600d Combustion gas 70a, 70b, 72a, 72b, 74a, 74b Hoppers 71a, 71b, 73a, 73b Valves 75a, 75b Rotary valves 76, 77 Particle transfer devices 700a, 700b, 700c, 700d Coal gasification gas 8 Flow control valve 9 Lower gasifier 9A Lower gasifier Fluidized bed 900,901 Exhaust ash

Front page continued (72) Inventor Shigeyasu Ishigami 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (72) Toshimitsu Ichinose 5-717-1, Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries Stock Ltd. Company Nagasaki Institute

Claims (2)

[Claims] 1. Coal, coal and gasification gas are formed by using coal, air and combustion gas as a fluidizing particle for coal and the char produced thereby to form a fluidized bed by using the combustion gas and air as fluidizing gas. And a liquefaction gas that is converted to char, and limestone is supplied to the limestone as fluidization particles, and the coal gasification gas supplied from the gasification furnace 1 is used as a fluidization gas to form a fluidized bed. Sulfur compounds in coal gasification gas
A desulfurization furnace that fixes as CaS, receives char from the gasification furnace to oxidize unburned matter in the char, and also receives desulfurization agent from the desulfurization furnace to supply CaS in the desulfurization agent to CaSO ₄
And a heat exchanger that heats the fluid with the heat generated by these oxidation reactions, and supplies the combustion gas to the gasification furnace as the combustion gas, the gasification furnace, and the oxidation furnace. A char transfer device that receives char from the gasification furnace and raises the pressure to the oxidation furnace to transfer the char to the oxidation furnace, and a desulfurizing agent connected to the desulfurization furnace and the oxidation furnace to receive a desulfurizing agent from the desulfurization furnace A coal gasifier comprising a desulfurization agent transfer device for increasing the pressure to the oxidation furnace and transferring the desulfurization agent to the oxidation furnace. 2. A gas dispersion plate in which the desulfurization furnace forms a fluidized bed of the limestone, and a fluidized bed disposed in the fluidized bed to limit the movement of particles in the fluidized bed so that the fluidized bed is in an upper fluidized bed and a lower fluidized bed. An internal dispersion plate divided into a fluidized bed, a heat exchanger is disposed in the upper fluidized bed, and the temperature of the upper fluidized bed is 800 °
The limestone is supplied while being maintained at 900 ° C., the lower fluidized bed is supplied with coal gasification gas from the coal gasification furnace through the gas dispersion plate, and the temperature of the lower fluidized bed is 90.
The temperature is maintained at 0 ° to 1000 ° C.
The coal gasifier described.