JP4428683B2 - Gas purification system and gas purification method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas purification system and a gas purification method provided with a dry gas purification device, and more particularly to a gas purification system and a gas purification method provided with a dry gas purification device using a dry gas purification method with high thermal efficiency.
[0002]
[Prior art]
When the thermal energy of the gas generated by heating and solidifying solid fuel or organic waste and then gasifying it is used for power generation or converted to fuel, harmful gases contained in the generated gas It is necessary to detoxify acidic components. In general, a wet gas purification method is employed as the method.
[0003]
Wet gas purification methods include chemical absorption methods such as the MEA (monoethanolamine) method, physical absorption methods such as the seleczole method, and direct oxidation methods. Absorption methods are often used, and the physical absorption method is mainly used for power generation.
[0004]
[Problems to be solved by the invention]
However, since the wet gas purification method treats the generated gas with water, it is cooled to about 100 ° C. or less, cannot use the high-temperature thermal energy of the generated gas, and has a problem that the thermal efficiency is extremely poor. is there. In other words, the heat energy generated by gasification can be used for gas turbines and the like with higher efficiency as the temperature is higher, and the power generation efficiency is also higher. Therefore, it is desirable to exclude harmful acidic components while keeping the temperature as high as possible. However, conventional wet gas purification methods cannot be used with high thermal efficiency. In addition, in the case of the wet gas purification method, it is necessary to perform wastewater treatment, which requires a large amount of space and complicated equipment.
[0005]
Accordingly, an object of the present invention is to provide a gas purification system and a gas purification method including a dry gas purification device that can be used with high thermal efficiency while preserving the thermal energy of a gas generated by heating waste or the like as much as possible. There is to do.
[0006]
[Means for Solving the Problems]
The above object can be achieved by the inventions described in the claims. That is, the characteristic configuration of the dry gas purifying apparatus according to the present invention includes a mixer that supplies and mixes a gas generated by a gasifier with an alkaline chemical that is heated and becomes porous, and is mixed by the mixer. And a dust collecting means for treating the reaction product in the product gas that has been neutralized.
[0007]
According to this configuration, since the acidic component contained in the product gas generated by the gasifier is effectively neutralized and purified, there is no need to pass water as in the wet gas purification method. The thermal energy of the gas can be stored and used without impairing, and high thermal efficiency can be achieved during use. In addition, the product gas can be purified at normal pressure, and there is no need for incidental facilities associated with high-pressure gas operation, and the manufacturing cost of the apparatus can be reduced.
[0008]
As a result, to provide a dry gas purification device that can be used with high thermal efficiency while preserving the thermal energy of gas generated by heating solid fuel, various industrial wastes, general wastes such as garbage, etc. I was able to.
[0009]
The alkaline chemical is sodium hydrogen carbonate, and a pulverizer for finely pulverizing the sodium hydrogen carbonate is provided, and the sodium hydrogen carbonate pulverized by the pulverizer is supplied to the mixer together with an inert gas. Is preferred.
[0010]
According to this configuration, sodium hydrogen carbonate that has been finely pulverized by a pulverizer and has increased activity efficiently neutralizes and reacts with acidic components in the product gas in the mixer, thereby further improving the acidic components in the product gas. Can be removed.
[0011]
Further, the gas purification system according to the present invention is characterized by a ceramic filter disposed downstream of the gasifier and removing the gas produced by the gasifier, and the produced gas removed by the ceramic filter. A heat recovery apparatus that recovers heat from the heat recovery apparatus and a dry gas purification apparatus according to claim 1 or 2 that purifies the product gas that has passed through the heat recovery apparatus.
[0012]
According to this configuration, the generated gas generated by the gasifier is removed from the contained dust by the ceramic filter, and can be used in boiler equipment etc. with high thermal energy. Since it is effectively neutralized and removed by the apparatus and purified, it is not necessary to pass the product gas through water as in the wet gas purification method. Therefore, it can be stored and used without impairing the thermal energy of the product gas, High thermal efficiency can be achieved. In addition, since no dust removal equipment that requires high pressure is provided, the generated gas can be purified at normal pressure, and no additional equipment for high-pressure gas operation is required, and the entire system can be configured at low cost.
[0013]
As a result, it was possible to provide a gas purification system that can be used with high thermal efficiency while preserving the thermal energy of the generated gas as much as possible and that can be operated at normal pressure.
[0014]
Furthermore, the gas purification method according to the present invention is characterized in that the gas generated by heating / decomposing waste is removed by a ceramic filter, and heat is recovered from the generated gas that has been removed from the dust, and the generated heat is recovered. The object is to supply and mix an alkaline chemical which is heated and becomes porous to the gas, and collect and purify the reaction product in the mixed and neutralized product gas.
[0015]
According to this configuration, it was possible to provide a gas purification method that can be used with high thermal efficiency while preserving the thermal energy of the gas generated by heating waste or the like as much as possible.
[0016]
It is preferable that the alkaline chemical is sodium hydrogen carbonate, which is finely pulverized, fed with an inert gas, and mixed with the product gas.
[0017]
According to this structure, the sodium hydrogen carbonate whose activity has been increased can be efficiently neutralized with the acidic component in the product gas, and the acidic component in the product gas can be removed more effectively.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic overall configuration of a gas purification system according to the present embodiment. A raw material such as various solid fuels and organic wastes is put into a gasification furnace 1 which is a kind of gasifier, heated, decomposed, gasified, and the produced gas is cooled without being cooled. The dust inside the gas that is harmful when the heat is recovered so as to recover the high-temperature energy of the generated gas is removed. The gas generated by the gasification furnace 1 is usually heated to around 900 ° C., depending on the properties of the waste. Therefore, a ceramic filter 2 having heat resistance such as silicon nitride, alumina, or carbon nitride is used. As the pore diameter of the ceramic filter, it is sufficient if fly ash in the exhaust gas can be removed, and usually a pore size of about several tens of μm can be used.
[0019]
The dust-removed gas receives an appropriate amount of water and is recovered by the heat recovery unit 3 having a heat exchange function, and the heat energy is sent to the boiler facility 4 and used effectively. Specifically, the water supply in this case depends on the scale of the boiler facility 4, but is heated to about 200 ° C. when discharged from the heat recovery unit 3 using, for example, steam heated to about 120 ° C. To the boiler equipment 4.
[0020]
This gas purification system does not need to cool the produced gas to a low temperature unlike the conventional wet gas purification system, and can use the high thermal energy of the produced gas as it is, so that the utilization efficiency is extremely high. In addition, since the dust is removed from the product gas, the heat transfer coefficient of the product gas is improved, the high-temperature energy of the product gas can be used effectively, and high thermal efficiency can be achieved. In addition, since dust is removed from the generated gas, it is possible to remarkably reduce the occurrence of wear and corrosion in the water pipe constituting the heat recovery device 3, and it is possible to extend the life of the water pipe and increase the temperature of the steam.
[0021]
The heat-recovered gas is further sent to a dry gas refining device to remove acidic components in the product gas. First, the product gas is fed to a mixer 5 such as an ejector, where sodium bicarbonate powder is sprayed and mixed, and the acidic components in the product gas are neutralized. This sodium hydrogen carbonate is a granular material of about several tens of μm to several mm at the beginning, and this is supplied to a pulverizer 7 by a cutting device 6 such as a table feeder with a screw. It is pulverized to a fine powder size. The powdered sodium hydrogen carbonate is generally easily clogged in a pipe or the like sent to the pulverizer 7, but is provided to the pulverizer 7 by providing the cutting device 6.
[0022]
Fine powder sodium hydrogen carbonate is blown into the mixer 5 together with an inert gas, and is sufficiently mixed with the product gas. As the inert gas, water vapor, air or the like can be used as long as it does not combust the product gas, and it includes nitrogen, etc. in addition to helium, argon, etc. These are the properties of the product gas. However, it is preferable to use nitrogen because it is inexpensive and does not burn the generated gas.
[0023]
The product gas mixed with sodium hydrogen carbonate effectively reacts with sodium hydrogen carbonate whose porosity has been promoted by the residual heat of the product gas, and the acidic components in the product gas are neutralized, and the product gas The acidic component of is removed. That is, sodium bicarbonate is heated to a temperature range of about 140 to 300 ° C., so that it is decomposed as shown in the following formula, gas components are volatilized, become porous, and activated Na ₂ CO _3. It becomes.
[0024]
2NaHCO ₃ → Na ₂ CO ₃ + CO ₂ + H ₂ O
The porous activated Na ₂ CO ₃ produced in this way reacts effectively with the acidic components in the product gas and exhibits a remarkable desulfurization and desalination effect equivalent to or better than that of wet processing. As a result, the neutralization reaction of the gas is promoted. In this case, it is preferable that sodium bicarbonate is added in an amount corresponding to the amount of acidic components in the gas. For this purpose, the amount of acidic components in the gas may be monitored upstream of the mixer 5 and the amount of sodium hydrogen carbonate charged may be controlled automatically or manually based on the result. The method for measuring the amount of acidic components in the gas is not particularly limited, and various gas sensors may be provided, and a method of controlling the input amount of sodium bicarbonate by feeding back the measurement results may be considered. For measurement of acidic components in the gas, a semiconductor gas absorption spectroscopic laser type gas analyzer may be employed, and when this is used, the detection speed is fast, so that the control can be performed with good timing.
[0025]
The reaction gas is removed from the neutralized product gas by a dust collector 8 such as a bag filter or a ceramic filter (particularly preferable when the product gas is high temperature), which is a dust collecting means, and is purified and rendered harmless. . At this stage, the generated gas is, for example, about 200 to 300 ° C., and can be further fed to a gas turbine or the like to effectively contribute to power generation. Naturally, the product gas is purified and may be discharged into the atmosphere.
[0026]
As described above, in the case of the gas purification system according to the present embodiment, since it can be operated at normal pressure without increasing the pressure, it is not necessary to make the gasifier etc. particularly complicated and large, and the manufacturing cost of the entire system In addition, the operating cost or the cost required for maintenance can be significantly reduced as compared with the conventional dry purification system.
[0027]
[Another embodiment]
(1) The gasification apparatus that can be implemented in the present invention is not particularly limited, and includes a stoker furnace, various gasification melting furnaces such as a kiln type, a fluidized bed type, and a shaft furnace type, and other various incinerators, Any device that heats and decomposes gas including waste containing organic waste may be used.
[Brief description of the drawings]
FIG. 1 is a schematic overall block diagram of a gas purification system according to an embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Gasifier 2 Ceramic filter 3 Heat recovery device 5 Mixer 7 Crusher 8 Dust collection means

Claims (2)

A gasifier that inputs solid fuel and / or waste, heats and decomposes, and generates a gas heated to 900 ° C. or a temperature around 900 ° C.,
A ceramic filter disposed on the downstream side of the gasifier and removing dust generated by the gasifier;
A heat recovery device for recovering heat from the produced gas removed by the ceramic filter;
A gas purification system comprising a dry gas purification device for purifying the product gas that has passed through the heat recovery device,
The dry gas purifier is
A pulverizer for finely pulverizing sodium bicarbonate that is heated to become porous;
A mixer for supplying and mixing sodium bicarbonate finely pulverized by the pulverizer together with an inert gas into the gas sent from the heat recovery device;
A dust collecting means for treating the reaction product in the product gas mixed and neutralized by the mixer,
A gas purification system characterized in that the gas temperature after being treated by the dust collecting means is configured to 200 to 300 ° C., and the gas can be provided to the power generation means. Solid fuel and / or waste is heated and decomposed to produce gas heated to 900 ° C or a temperature around 900 ° C,
The generated gas is removed by a ceramic filter,
Heat recovery from the dust-generated product gas and heat-recovered product gas is pulverized sodium hydrogen carbonate that is heated and porous, mixed with an inert gas, and mixed,
The reaction product in the mixed and neutralized product gas is purified by collecting dust to obtain a product gas having a temperature of 200 to 300 ° C.,
A gas purification method characterized in that a gas having a temperature of 200 to 300 ° C. can be provided to a power generation means .

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