JP2011105890A - Circulating fluidized bed gasification reactor - Google Patents

Abstract

Provided is a gasification reactor that can efficiently remove even light tar in a system by a simple method and can reduce the cost of tar treatment.
A raw material is gasified in a fluidized bed gasification furnace into which a fluidized medium is introduced, and char and fluidized medium generated at the time of gasification are introduced into a subsequent fluidized bed combustion furnace to burn unburned components. At the same time, in the circulating fluidized bed gasification reactor configured to circulate the reheated fluidized medium in the reactor, a multistage cyclone is provided at the rear stage of the fluidized bed combustion furnace, Tar adsorbent particles and / or ash particles having a relatively large particle size are discharged to the outside of the furnace, and separated from exhaust gas by the second and subsequent cyclones.
[Selection] Figure 2

Description

  The present invention relates to a circulating fluidized bed gasification reactor for extracting a combustible gas from a fuel using a circulating fluidized bed, and in particular, a solid fuel such as coal, biomass, garbage, sewage sludge or the like of hydrocarbon resources. The present invention relates to a circulating fluidized bed gasifier reactor that absorbs even light tar at a low cost and takes out a product gas with high efficiency in a gasifier reactor that uses liquid fuel with a large amount of tar.

Conventionally, technologies have been developed to make effective use of organic resources by using solid fuels of hydrocarbon resources such as coal, biomass, garbage, and sewage sludge, and using the generated gas as a combustible gas and heat source. Yes.
As one of the gasifiers, a reaction furnace is separated into a fluidized bed gasifier and a fluidized bed combustion furnace, a hydrocarbon resource fuel is supplied to the fluidized bed gasifier and gasified with steam or the like. And the fluidized medium is introduced into the fluidized bed combustion furnace and burned, and the unburned char and fluidized medium are separated from the head of the combustion furnace by a cyclone or the like and then returned to the fluidized bed gasification furnace. Some have used a circulating fluidized bed.

In such a gasification furnace, tar is generated with gasification, but it is necessary to decompose the tar, and various proposals have been made for this purpose.
For example, Patent Document 1 discloses that in a reaction furnace in which a combustion furnace and a gasification furnace are separated, a catalyst packed bed is provided in the gasification furnace, and the time for contacting with tar at a high temperature is increased, so that tar can be efficiently obtained. It has been proposed to break down.
Further, in Patent Document 2, a tar adsorption tower is provided at the rear stage of the gasification furnace, the tar is adsorbed by ash or alumina, and the particles after adsorption are supplied to the combustion furnace and used as a heat source.
Furthermore, Patent Document 3 proposes that tar is cooled and condensed to be efficiently adsorbed on particles.

JP 2007-146036 A JP 2008-260801 A JP 2003-251168 A Japanese Patent Application No. 2009-175233

However, the technique of Patent Document 1 has a problem that the catalyst is mixed with the fluid medium or mixed with the ash particles.
Further, in the method of Patent Document 2, when expensive particles such as alumina are used, there is a problem that they are mixed with a fluid medium or ash particles.
Furthermore, in the method of Patent Document 3, since tar is removed from the tar-adsorbed particles separately using a remover in the tar removal chamber, the cost is high.

  The present invention provides a gasification reactor that solves such problems in the prior art and can efficiently remove even light tar in the system by a simple method and can reduce the cost of tar treatment. It is for the purpose.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have obtained a part of the tar-adsorbing particles and fly ash circulating in the circulating fluidized bed gasification reactor so that the tar absorption at the latter stage of the furnace. It has been found that the problem can be solved by providing a function for cooling to a temperature at which it can be continuously supplied to the tower, or further, due to the difference in tar components, the temperature can be efficiently removed.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
[1] The raw material is gasified in the fluidized bed gasification furnace into which the fluidized medium is introduced, and the char and fluidized medium generated during the gasification are introduced into the subsequent fluidized bed combustion furnace to burn the unburned portion. A circulating fluidized bed gasification reactor configured such that the reheated fluidized medium circulates in the reactor, wherein the circulating fluidized bed combustion reactor has a multistage cyclone in the subsequent stage of the fluidized bed combustion furnace. Fluidized bed gasification reactor.
[2] The first stage cyclone releases tar adsorbent particles and / or ash particles having a relatively large particle size to the outside of the furnace and is separated from exhaust gas by the second and subsequent cyclones. The circulating fluidized bed gasification reactor of [1] above.
[3] The circulating fluidized bed gasification reaction of [2], wherein the collected tar adsorbing particles and / or ash particles are supplied to a tar absorption tower provided at the pyrolysis gas outlet to adsorb the tar. Furnace.
[4] The circulating fluidized bed gasification reactor according to [3], wherein the tar absorption tower has a cooling function.
[5] The tar adsorbing particles that adsorb tar and / or the ash particles that adsorb tar are supplied to the coke residue combustion furnace and the char residue combustion furnace, respectively, and used as a heat source. The circulating fluidized bed gasification reactor according to the above [3] or [4].

  According to the present invention, a part of tar adsorbing particles and fly ash circulating in a circulating fluidized bed gasification reactor can be continuously supplied to a tar absorption tower downstream of the furnace, Due to the difference in components, it also has a function of cooling to a temperature that can be efficiently removed. Also, depending on the fuel, tar components generated at the same time as pyrolysis or gasification differ, and the condensation temperature differs, and even if a tar-adsorbing substance is used in the gasification furnace, the characteristics of the device (gas residence time) In addition, even if tar is scattered outside the furnace, it can be efficiently removed without supplying a new adsorbent.

The figure which shows typically embodiment of the circulating fluidized bed gasification reactor which the present inventors have already proposed. The figure which shows typically the multistage cyclone in the circulating fluidized-bed gasification reactor of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

  FIG. 1 is a diagram schematically showing an embodiment of a circulating fluidized bed gasification reactor that has already been proposed by the present inventors (see Patent Document 4), and shows a tar absorption furnace and a fuel pyrolysis. A fuel pyrolysis furnace having a two-stage furnace with upper and lower furnaces, a char gasification furnace and a char residue combustion furnace are connected in this order to the lower stage of the fuel pyrolysis furnace, and the upper tar absorption furnace In the subsequent stage, a coke gasification furnace and a coke residue combustion furnace are connected in this order. The char gasification furnace and the coke gasification furnace are two-stage fluidized bed gasification furnaces provided at the lower stage and the upper stage, respectively, and the char residue combustion furnace and the coke residue combustion furnace are independently flowable. It consists of a layer combustion furnace.

  According to the apparatus shown in FIG. 1, since the upper and lower sides of the pyrolysis furnace are separated into two stages, a fuel pyrolysis furnace and a tar absorption furnace, a fluid medium having good tar adsorption efficiency such as porous particles, for example, By supplying the porous alumina only to the upper tar absorption furnace, there is an advantage that the amount of use can be minimized. Furthermore, the fluid medium can be separately circulated in a system comprising a fuel pyrolysis furnace, a char gasification furnace and a residue char combustion furnace, and a system comprising a tar absorption furnace, a coke gasification furnace and a residue coke combustion furnace. Therefore, it is possible to prevent the fluid medium having good tar adsorption efficiency such as porous particles from mixing with the ash particles.

  In the circulating fluidized bed gasification reactor shown in the figure, the fluid medium that adsorbs the tar taken out from the upper tar absorption furnace passes through the coke gasification furnace and the coke residue combustion furnace connected to the subsequent stage to the tar absorption furnace. On the other hand, the fluid medium taken out from the lower fuel pyrolysis furnace is returned to the fuel pyrolysis furnace through the char gasification furnace and the char residue combustion furnace connected to the subsequent stage.

Porous particles such as porous alumina are preferably used in order to efficiently absorb tar generated from the raw material, but have the disadvantage of being expensive.
In the circulating fluidized bed gasification reactor according to the present invention, a thermal decomposition furnace having a two-stage furnace structure having a tar absorption furnace and a fuel pyrolysis furnace at the top and bottom is provided in the upstream of the fluidized bed gasification furnace. As a fluid medium for the tar absorption furnace of the present invention, those having good tar adsorption efficiency such as porous particles are used, and the fluid medium introduced into the fuel pyrolysis furnace at the lower stage is generally used inexpensive cinnabar It is possible to minimize the amount of the expensive fluid medium used by using a material containing as a main component.
In addition, since the char residue combustion furnace and the coke residue combustion furnace are separated, fluid media such as porous particles circulating in the upper tar absorption furnace should not be mixed with the ash particles generated in the char residue combustion furnace. it can.
Further, since tar treatment can be performed in the furnace, the cost conventionally required for the tar treatment at the latter stage of the furnace can be reduced.

Hereinafter, the gasification of the raw material is performed using an example in which porous particles such as porous alumina are used for the fluid medium of the upper tar absorption furnace and dredged sand is used for the fluid medium of the lower fuel pyrolysis furnace. This will be specifically described.
A hydrocarbon-based solid fuel such as biomass, garbage, sewage sludge, and coal is supplied to the fuel pyrolysis furnace, and for example, CO ₂ gas in which a part of the generated combustion gas is circulated from the lower part, or An inert gas such as N ₂ or Ar is introduced as a flowing gas, and the above hydrocarbon solid fuel supplied to the fuel cracking furnace is pyrolyzed.
The tar generated simultaneously with the generated pyrolysis gas flows to the upper tar absorption furnace. The tar is adsorbed by the porous particles in the tar absorption furnace and partly reformed into gas. The pyrolysis gas containing no tar can be taken out from the pyrolysis gas take-out means provided at the top.
The extracted pyrolysis gas is a kind of combustible gas, and is used for power generation by a fuel cell or a gas engine, liquid fuel, and the like.
In the present invention, the raw material for gasification is not limited to the hydrocarbon-based solid fuel as described above, and a liquid fuel that easily generates tar can also be used.

In the lower fuel pyrolysis furnace, the pyrolyzed char and cinnabar are sent to the next char gasification furnace.
On the other hand, the porous particles having adsorbed tar in the upper tar absorption furnace are sent to the upper coke gasification furnace.

The char gasification furnace and the coke gasification furnace are in a two-stage fluidized bed having the respective furnaces in the lower stage and the upper stage, and the char and coke introduced into each furnace are combined with the gasifying agent introduced from the lower part. It is gasified by the gasification reaction. As the gasifying agent, water vapor, oxygen, air, or the like is used. The gasification gas produced by reacting with the gasifying agent is taken out from the upper part of the coke gasification furnace.
The extracted gasification gas is a combustible gas, and is used for power generation by a fuel cell or a gas engine, liquid fuel, or the like.

  In the apparatus shown in FIG. 1, the pyrolysis gas taken out from the upper part of the tar absorption furnace and the gasification gas taken out from the upper part of the coke gasification furnace are taken out separately. May be used after being merged after each furnace outlet, and when used as a heat source, a heat exchanger may be attached before or after the merge.

The residue char in the char gasification furnace and the residue coke in the coke gasification furnace are respectively introduced into the next residue char combustion furnace and residue coke fuel furnace provided separately.
Both the residue char combustion furnace and the residue coke combustion furnace are fluidized beds, and ensure a residence time during which the residue char and residue coke can be completely combusted. In each combustion furnace, the introduced residue char and residue coke are burned together with air or oxygen introduced from the lower part of each combustion furnace, and the combustion gas is extracted from the extraction means provided in the upper part of each furnace by a cyclone. It is taken out.

FIG. 2 is a diagram schematically showing a multistage cyclone in the present invention.
As shown in FIG. 2, the gasification reaction furnace of the present invention has a multistage cyclone at the outlets of the char residue combustion furnace and the coke residue combustion furnace.
In other words, in the multistage cyclone provided at the rear stage of the coke residue combustion furnace, the tar adsorbent particles having a relatively large particle size are scattered together with the exhaust gas by lowering the separation efficiency between the first stage tar adsorbent particles and the fuel gas. And then separate and collect each in the second and subsequent cyclones. The collected tar-adsorptive particles are supplied to a tar absorption tower using tar-adsorptive particles provided at the pyrolysis gas outlet to adsorb tar.
Similarly, in the multistage cyclone installed at the rear stage of the char residue combustion furnace, the fly ash having a larger particle size than the conventional one is scattered together with the exhaust gas by lowering the separation efficiency of the first stage ash and fuel gas. Drain outside and collect each in the second and subsequent cyclones. The collected fly ash is supplied to a tar adsorption tower using fly ash provided at the pyrolysis gas outlet to adsorb tar.
As long as the material is sealed, such as a loop seal, an L-type valve, and a moving bed, the communication path until the tar-adsorbing particles and fly ash separated by the cyclone are supplied to the tar absorption tower may be any type. .

Since the amount and components of tar generated together with gas differ depending on the fuel, each tar absorption tower is cooled to a temperature with high adsorption efficiency in accordance with the components, and tar is efficiently adsorbed. Thereby, even if tar is scattered with the gas to the outside of the furnace due to the characteristics of the gasification furnace, the tar can be removed by a simple method with low cost.
Furthermore, as a method of using the adsorbed tar, fly ash can be returned to the char residue combustion furnace, and tar adsorbent particles can be effectively used as a heat source by returning them to the coke residue combustion furnace.
In this figure, the order of the tar absorption tower is the fly absorption ash tar absorption tower in the previous stage, but there is no problem even if the tar adsorption particle adsorption tower is in the previous stage.
Further, the present method is not limited to the latter stage of the pyrolysis gas, and such a tar absorption tower may be provided after the gasification gas.

On the other hand, the combustion gas collected by each second-stage cyclone is mainly used as a heat source, and as described above, a part of it can be recycled to the fuel pyrolysis furnace. is there. It can also be used as a preheating source for air or steam introduced into the gasification furnace or each combustion furnace.
Further, the tar adsorbing particles and fly ash separated by the first-stage cyclone are returned to the tar absorption furnace and the fuel pyrolysis furnace, respectively.
Note that the char concentration is closely related to the reaction (especially shift reaction) occurring in the gasification furnace, and if the heat balance is within the range, a part of the unburned char is recirculated, By controlling the char concentration in the gasification furnace to a concentration suitable for the reaction, for example, the H ₂ / CO ratio at the time of gasification can be controlled, and the use for liquid fuel is advantageous.
Furthermore, if the heat balance cannot be established with only the combustion heat obtained from the residue char and residue coke, the heat balance is maintained by supplying a predetermined amount of pyrolysis gas and gasification gas to each combustion furnace and burning them. It is also possible to do.

  The fuel pyrolysis furnace and the char gasification furnace, the char gasification furnace and the residue char combustion furnace, the tar absorption furnace and the coke gasification furnace, or the communication passages connecting the coke gasification furnace and the residue coke combustion furnace are loop seals, L type Any type of material can be used as long as the material can be sealed, such as a valve or moving layer.

  As described above, in the circulating fluidized bed gasification reactor shown in FIGS. 1 and 2, the flow of the fluid medium and the solid fuel introduced into the lower fuel pyrolysis furnace is as follows. → Char gasification furnace → Communication passage → Char residue combustion furnace → Cyclone → Downcommer → Fuel pyrolysis furnace The flow of fluid medium introduced into the upper tar absorption furnace is the tar absorption furnace → Communication passage → Coke gasification furnace → communication passage → coke residue combustion furnace → cyclone → downcomer → tar absorption furnace. On the other hand, the flow of tar-adsorbing particles scattered outside the system becomes a tar absorption tower → coke residue combustion furnace, and the flow of fly ash scattered outside the system becomes a tar absorption tower → char residue.

In the present invention, the circulating fluidized bed gasification reactor is not limited to that shown in FIG. 1 as long as it has at least a fluidized bed gasification furnace and a fluidized bed combustion furnace.
For example, the fuel pyrolysis furnace described above is a furnace having an alkali absorption function, and the char gasification efficiency is improved by actively adsorbing the alkali in the volatile gas to the char and using it as a gasification catalyst. Can do.
Further, in the apparatus shown in FIG. 1, the gasification furnace has a two-stage structure in which a char gasification furnace and a coke gasification furnace are provided in the lower stage and the upper stage, respectively, and the generated gasification gas is taken out from the upper coke gasification furnace. The gasification furnaces are configured as separate gasification furnaces, the gasifying agent is introduced from the lower part of each gasification furnace, and the generated gasification gas is provided at the upper part. You may comprise so that it may take out from an extraction means.
Furthermore, the char gasification furnace may not be provided, and a char residue combustion furnace may be directly connected to the rear stage of the fuel pyrolysis furnace. That is, if the solid fuel used is a high volatile solid fuel and the thermal balance of the system is established by merely burning the pyrolysis gas and its residue without gasifying the char, that is, after pyrolysis, When the residual char is gasified, the char gasification furnace can be omitted as shown in the present embodiment when the heat of combustion is insufficient.
Furthermore, the coke gasification furnace may not be provided, and the coke residue combustion furnace may be directly connected to the rear stage of the tar absorption furnace.
Alternatively, there is no char gasification furnace or coke gasification furnace, a coke residue combustion furnace is directly connected to the latter stage of the tar absorption furnace, and a char residue combustion furnace is directly connected to the latter stage of the fuel pyrolysis furnace. May be.

  The system in the circulating fluidized bed gasification reactor of the present invention is applied to the utilization of unused hydrocarbon resources such as biomass, garbage, sewage sludge, and, for example, hybrid gasification (cogasification) with coal and biomass. Alternatively, it can also be applied to hybrid gasification of solid fuel and liquid fuel.

Claims (5)

  The raw material is gasified in the fluidized bed gasification furnace into which the fluidized medium is introduced, and the char and fluidized medium generated during the gasification are introduced into the subsequent fluidized bed combustion furnace to burn the unburned components and reheat. A circulating fluidized bed gasification reactor configured such that the fluidized medium circulated in the reaction furnace has a multistage cyclone in the subsequent stage of the fluidized bed combustion furnace. Chemical reactor.   The tar-adsorbing particles and / or ash particles having a relatively large particle size are discharged out of the furnace in the first-stage cyclone, and separated from the exhaust gas in the second-stage and subsequent cyclones. 2. The circulating fluidized bed gasification reactor according to 1.   The circulating fluidized bed gasification reactor according to claim 2, wherein the collected tar adsorbing particles and / or ash particles are supplied to a tar absorption tower provided at a pyrolysis gas outlet to adsorb the tar.   The circulating fluidized bed gasification reactor according to claim 3, wherein the tar absorption tower has a cooling function.   The tar adsorptive particles that adsorb tar and / or the ash particles that adsorb tar are supplied to the coke residue combustion furnace and the char residue combustion furnace, respectively, and used as a heat source. The circulating fluidized bed gasification reactor according to claim 3 or 4.

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