The present invention relates to a method and an apparatus for reforming tar in a gasification equipment.
Conventionally, a fuel gasification equipment for production of a gasification gas has been developed, using solid fuel such as coal, biomass, waste plastic or various wet wastes, as fuel.
In general, when the solid fuel is gasified at low temperature (600-900° C.) in a gasification furnace, a resultant gasification gas contains tar. Since the tar contained is condensed into mist as the gasification gas is lowered in temperature, utilization of the gasification gas as, for example, a raw material for chemical synthesis may cause problems such as pipe clogging and other troubles in devices due to tar and poisoning of synthetic catalysts due to adhesion of tar in a downstream refinery or chemical synthesis process.
Tar reforming at high temperature is a conventional technique for removal of the tar component in the gasification gas. In this technique, as shown in
A general technical level pertinent is disclosed, for example, in Patent Literature 1 where a fuel gas containing a tar component is raised in temperature, using a heat storage body and a combustion assist gas, into a high temperature of 1100° C. or more to thermally decompose and remove the tar component.
However, such reforming of the tar component with the temperature raising to about 1100-1500° C. by combustion of the gasification gas in the reforming furnace 2 with addition of oxygen or air necessitates the combustion of the gasification gas in large quantity for temperature raising up to the reaction temperature, with a disadvantageous result that the gasification gas to be provided as a product has a substantially lowered calorific value.
The invention was made in view of the above and has its object to provide a method and an apparatus for reforming tar in a gasification equipment capable of reforming tar by temperature raising of a gasification gas by means of very small oxygen and combustion amounts while minimizing the lowering of a calorific value in the gasification gas, capable of preventing troubles in downstream devices due to tar and also capable of achieving heat recovery of the gasification gas at a low temperature by a metallic heat exchanger, leading to effective utilization of the thermal energy without waste.
The invention is directed to a method for reforming tar in a gasification equipment wherein fuel is gasified with a gasification agent in a gasification furnace to produce a gasification gas, said gasification gas being introduced into a reforming furnace where a tar component in the gasification gas is reformed,
characterized in that the gasification gas containing tar and produced in the gasification furnace is heat-exchanged in a ceramic heat exchanger with a reformed gasification gas from the reforming furnace for temperature raising of said gasification gas before introduction thereof into the reforming furnace.
As in the method for reforming tar in the gasification equipment according to the invention, when the gasification gas containing tar and produced in the gasification furnace is heat-exchanged in the ceramic heat exchanger with the reformed gasification gas from the reforming furnace for temperature raising of said gasification gas before introduction thereof into the reforming furnace, the combustion of the gasification gas in large quantity becomes unnecessary for temperature raising to the reaction temperature for reforming of the tar component; oxygen input to the reforming furnace may be suppressed; substantial lowering of a calorific value in the gasification gas to be provided as a product may be prevented; troubles in downstream devices due to tar may be prevented; and heat recovery of the gasification gas at a low temperature may be achieved with a metallic heat exchanger, leading to reduction of waste of thermal energy.
In the method for reforming tar in the gasification equipment, it is preferable that a portion of fuel to be supplied to the gasification furnace is burned in a combustion furnace to supply a resultant exhaust combustion gas to a ceramic tube disposed in the reforming furnace for temperature raising of the gasification gas in the reforming furnace to thereby reform a tar component in the gasification gas, which brings about the reforming of the tar component without the combustion of the gasification gas at all and prevents dilution of the gasification gas with the exhaust combustion gas.
In the method for reforming tar in the gasification equipment, it is preferable that air for said combustion furnace is heat-exchanged in metallic and ceramic heat exchangers with the exhaust combustion gas from the ceramic tube in said reforming furnace for temperature raising of the air before introduction thereof into the combustion furnace and for temperature lowering of the exhaust combustion gas from the ceramic tube before discharge thereof, which further enhances the efficiency.
The invention is also directed to an apparatus for reforming tar in a gasification equipment wherein fuel is gasified with a gasification agent in a gasification furnace to produce a gasification gas, said gasification gas being introduced into a reforming furnace to reform a tar component in the gasification gas,
characterized by comprising a ceramic heat exchanger for heat-exchanging the gasification gas containing tar and produced in the gasification furnace with a reformed gasification gas from the reforming furnace for temperature raising of said gasification gas before introduction thereof into the reforming furnace.
As in the apparatus for reforming tar in the gasification equipment according to the invention, when it comprises the ceramic heat exchanger for heat-exchanging the gasification gas containing tar and produced in the gasification furnace with the reformed gasification gas from the reforming furnace for temperature raising of said gasification gas before introduction thereof into the reforming furnace, the combustion of the gasification gas in large quantity becomes unnecessary for temperature raising to the reaction temperature for reforming of the tar component; oxygen input to the reforming furnace may be suppressed; substantial lowering of a calorific value in the gasification gas to be provided as a product may be prevented; troubles in downstream devices due to tar may be prevented; and heat recovery of the gasification gas at a low temperature may be achieved with a metallic heat exchanger, leading to reduction of waste of thermal energy.
In the apparatus for reforming tar in the gasification equipment, it is preferable that it further comprises
a combustion furnace for burning a portion of fuel to be supplied to said gasification furnace, and
a ceramic tube disposed in said reforming furnace and supplied with exhaust combustion gas from the combustion furnace for temperature raising of the gasification gas in the reforming furnace to thereby reform a tar component in the gasification gas, which brings about the reformation of the tar component without the combustion of the gasification gas at all and prevents dilution of the gasification gas with the exhaust combustion gas.
In the apparatus for reforming tar in the gasification equipment, preferably it further comprises metallic and ceramic heat exchangers for heat-exchanging air for the combustion furnace with the exhaust combustion gas from the ceramic tube before introduction of said air into the combustion furnace and for temperature lowering of the exhaust combustion gas before discharge thereof, which further enhances the efficiency.
According to a method and an apparatus for reforming tar in a gasification equipment of the invention, tar can be reformed by temperature raising of a gasification gas by means of very small oxygen and combustion amounts while minimizing the lowering of a calorific value in the gasification gas; troubles in downstream devices due to tar can be prevented; heat recovery of the gasification gas at a low temperature can be also achieved with a metallic heat exchanger, leading to effective utilization of the thermal energy without waste.
In the method for reforming tar in the gasification equipment of the invention, a portion of fuel to be supplied to the gasification furnace may be burned in a combustion furnace to supply a resultant exhaust combustion gas to a ceramic tube disposed in the reforming furnace for temperature raising of the gasification gas in the reforming furnace to thereby reform a tar component in the gasification gas, which brings about the reformation of the tar component without the combustion of the gasification gas at all and prevents dilution of the gasification gas with the exhaust combustion gas. In the apparatus for reforming tar in the gasification equipment of the invention, provision of the ceramic tube supplied with exhaust combustion gas from the combustion furnace for temperature raising of the gasification gas in the reforming furnace to thereby reform the tar component in the gasification gas can bring about temperature raising of the gasification gas without the combustion of the gasification gas at all and without dilution of the gasification gas with the exhaust combustion gas to reform the tar while further reliably suppressing the lowering of a calorific value of the gasification gas.
Furthermore, in the method for reforming tar in the gasification equipment of the invention, heat-exchange of the air for the combustion furnace in metallic and ceramic heat exchangers with the exhaust combustion gas from the ceramic tube in the reforming furnace can bring about temperature raising of the air before introduction thereof into the combustion furnace and temperature lowering of the exhaust combustion gas before discharge thereof, which further enhances the efficiency. In the apparatus for reforming tar in the gasification equipment of the invention, provision of metallic and ceramic heat exchangers for heat-exchange of the air for the combustion furnace with the exhaust combustion gas from the ceramic tube in the reforming furnace can bring about temperature raising of the air before introduction thereof into the combustion furnace and temperature lowering of the exhaust combustion gas before discharge thereof, which further enhances the efficiency.
1 gasification furnace
2 reforming furnace
3 ceramic heat exchanger
3a shell
3b ceramic tube
3c baffle plate
4 combustion furnace
5 ceramic tube
6 metallic heat exchanger
7 ceramic heat exchanger
Embodiments of the invention will be described with reference to the drawings.
The ceramic heat exchanger 3 is a so-called shell and tube heat exchanger as shown in
The operation of the embodiment will be described.
Fuel is gasified with a gasification agent in the gasification furnace 1 to produce the gasification gas containing tar which is heat-exchanged in the ceramic heat exchanger 3 with the reformed gasification gas from the reforming furnace 2 for temperature raising of the gasification gas before introduction thereof into the reforming furnace 2.
In the reforming furnace 2, the gasification gas is mixed with oxygen (or air) and is partly burned while oxidation or water vapor reforming reaction of the tar component proceeds.
The reformed gasification gas discharged from the reforming furnace 2 is led again to the ceramic heat exchanger 3 where the reformed gasification gas is heat-exchanged with the gasification gas containing tar and produced in the gasification furnace 1 for temperature lowering of the reformed gasification gas before introduction thereof into the downstream refinery or chemical synthesis process.
As a result, the combustion of the gasification gas in large quantity becomes unnecessary for temperature raising to the reaction temperature for the reforming of the tar component; oxygen input into the reforming furnace may be suppressed; substantial lowering of a calorific value of the gasification gas to be provided as a product may be prevented; troubles in downstream devices due to tar may be prevented; and heat recovery of the gasification gas at a low temperature may be achieved with a metallic heat exchanger (which may be incorporated in a line leading to the downstream refinery or chemical synthesis process although not particularly illustrated), which reduces the waste of thermal energy. Since the reforming furnace 2 may be controlled in temperature by changing the amount of oxygen, the temperature control is easily performed.
Thus, the gasification gas may be raised in temperature with very small oxygen and combustion amounts to reform tar while minimizing the lowering of a calorific value of the gasification gas; troubles due to tar may be prevented in downstream devices; and heat recovery of the gasification gas at a low temperature may be achieved with a metallic heat exchanger, leading to effective utilization of the thermal energy without waste.
a ceramic tube 5 disposed in the reforming furnace 2 and supplied with exhaust combustion gas from the combustion furnace 4 for temperature raising of the gasification gas in the reforming furnace 2 to thereby reform the tar component in the gasification gas, and
a metallic heat exchanger 6 (a lower temperature range of 800-900° C. or less) and a ceramic heat exchanger (a higher temperature range of 800-900° C. or more) which heat-exchange air for the combustion furnace 4 with the exhaust combustion gas from the ceramic tube in the reforming furnace 2 for temperature raising of the air before introduction thereof into the combustion furnace 4 and for temperature lowering of the exhaust combustion gas before discharge thereof.
In the embodiment shown in
Thus, in the reforming furnace 2, the gasification gas may be raised in temperature by the heat of the exhaust combustion gas from the combustion furnace 4 to the ceramic tube 5 without the combustion of the gasification gas at all and without dilution of the gasification gas with the exhaust combustion gas to thereby reform the tar component in the gasification gas. The reformed gasification gas discharged from the reforming furnace 2 is then led again to the ceramic heat exchanger 3 where the reformed gasification gas is heat-exchanged with the gasification gas containing tar and produced in the gasification furnace 1 for temperature lowering of the reformed gasification gas before introduction thereof into a downstream refinery or chemical synthesis process while the exhaust combustion gas discharged from the ceramic tube 5 in the reforming furnace 2 sequentially passes through the ceramic and metallic heat exchangers 7 and 6 and is heat-exchanged with the air for the combustion furnace 4 for temperature lowering of the exhaust combustion gas before discharge thereof.
As a result, in the embodiment shown in
Thus, in the embodiment shown in
It is to be understood that a method and an apparatus for reforming tar in a gasification equipment of the invention are not limited to the above embodiments and that various changes and modifications may be made within the scope of the invention.
Number | Date | Country | Kind |
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2008-058888 | Mar 2008 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP09/00958 | 3/3/2009 | WO | 00 | 6/24/2010 |