JP5762109B2 - Tar decomposition method and tar decomposition equipment - Google Patents

Description

  The present invention relates to a tar decomposing method and a tar decomposing facility for decomposing a tar component contained in a gasified gas of a combustible gas with a metal catalyst.

  In facilities that gasify waste (organic waste) containing organic matter such as wood chips and sewage sludge, biomass, and the like, a catalyst packed bed type tar decomposition facility for decomposing tar is installed. This catalyst has an appropriate temperature (for example, 700 to 950 ° C.). When the temperature falls below the appropriate temperature during operation, an oxidant (air, oxygen, oxygen-enriched air, etc.) is supplied to burn the gasified gas. The temperature is raised and the temperature is controlled within an appropriate range. There is a tar decomposition facility in which an oxidizing agent is supplied to a gas decomposition facility to burn gasified gas (Patent Document 1).

  However, the gasification gas is a reducing gas. When an oxidizing agent is supplied into the gasifying gas, soot is generated if the mixing of the oxidizing agent and the gasifying gas is not sufficient. In particular, in the gasification gas, aromatic hydrocarbons (benzene, toluene, naphthalene, anthracene, etc.), which are said to be soot precursors, exist as tars, and soot is easily generated. As described above, depending on the method of supplying the oxidant, soot may be generated and adhere to the catalyst itself, causing degradation of tar decomposition performance. Further, if soot accumulates on the catalyst layer, the catalyst layer may be blocked. .

  Gas combustion includes premixed combustion and diffusion combustion. Premixed combustion is a method of burning a premixed gas in which fuel and air are mixed in advance, and a gas stove is a typical example. Since fuel and air are mixed in advance, the combustibility is good, but there is a problem that backfire is likely to occur. On the other hand, diffusion combustion is a combustion system in which combustion and air (jet outlet) are in different locations, and combustion is promoted (flame is propagated) by gas diffusion at the interface between fuel and air. This is a representative example.

  If the oxidant is supplied alone to the high-temperature gasified gas atmosphere, the gasified gas is burned by diffusion combustion. However, even if the oxidant is simply supplied from the nozzle, the gas composition and gas amount of the gasified gas will fluctuate. In such a state, the combustion state constantly changes, so that a stable and good combustion state cannot be maintained, and there is a concern that soot may be generated.

JP 2010-1111779 A

  Therefore, the present invention has been made in view of the problems and situations of the above-described prior art, and its purpose is to supply a gas mixture of an oxidant and a combustible gas into the gasification gas, An object of the present invention is to provide a tar decomposition method and a tar decomposition apparatus that enable stable and good combustion.

The tar decomposition method according to the present invention is a tar decomposition method for decomposing a tar content contained in a flammable gasification gas with a metal catalyst, and the oxidation is carried out in a reaction vessel in which the metal catalyst is arranged. The temperature of the metal catalyst and / or the gasification gas is raised by supplying a mixed gas of the agent and the combustible gas, and tar decomposition is performed on the combustible gas in the mixed gas. In the case of using a gasified gas or a gasified gas that has been subjected to tar decomposition treatment and gas purification treatment, the amount of combustible gas in the mixed gas measures the combustible component in the gasification gas used. The theoretical oxygen amount is calculated based on the measurement result, and the gasification gas is fed so that the theoretical oxygen ratio is 1 or less .

With this configuration, the mixed gas (oxidant and combustible gas) is supplied into the gasified gas, and stable and good combustion (premixed combustion) can be performed, so that the generation of soot can be suppressed. Furthermore, since stable and good combustion can be maintained, the reaction temperature range in which the catalytic effect of the metal catalyst is effectively exhibited can be stably maintained, and tar decomposition efficiency can be dramatically improved. In other words, “1 or less of the theoretical oxygen ratio” is “1 or more times the theoretical oxygen amount”. This configuration is preferable because even if the combustible component in the gasification gas is not constant and varies, the amount of the combustible component of the mixed gas can be set within a predetermined range by measuring the combustible component in the gasification gas.

As an embodiment of the above method, the combustible gas in the mixed gas further includes any one type or a combination of two or more types selected from city gas, LP gas, and biogas.

  Since city gas and LP gas are distributed in the market, it is easy to secure supply. Examples of the biogas include methane fermentation and sewage sludge digestion gas. The gasification gas after the tar decomposition treatment by the tar decomposition facility can be used as a combustible gas that is a mixed gas component through a reflux path (pipe). Moreover, the gasification gas refined | purified with the gas purification equipment arrange | positioned downstream of a tar cracking equipment can be used for the combustible gas which is a mixed gas component through a recirculation | reflux path | route (piping). Since the temperature is lower than that of the gasified gas after the tar decomposition treatment, it is preferable because the installation of the control device can be facilitated.

  As an embodiment of the above method, the amount of the combustible gas mixed in the mixed gas is 1 or less of the theoretical oxygen ratio. The theoretical oxygen ratio is an oxygen amount ratio necessary for complete combustion (oxidation reaction) of a certain amount of combustible gas (combustible gas is set to 1). In other words, the amount of the combustible gas mixed in the mixed gas is one or more times the theoretical oxygen amount necessary for the combustible gas to completely burn. The reason is that the mixing amount of combustible gas (for example, external fuel, gasification gas to be processed) to be mixed is 1 or less of the theoretical oxygen ratio (or the theoretical air ratio) depending on factors such as the operating state, fuel, and device shape. It is because it is preferable to adjust.

In the present invention, when the mixing amount of the combustible gas is larger than 1 in the theoretical oxygen ratio, oxygen is left, which may cause diffusion combustion, which is not preferable. On the other hand, when the mixing amount of the combustible gas is smaller than the theoretical oxygen ratio of 1, oxygen is insufficient, but the temperature at which the temperature can be raised does not change much. That is, for example, when the gas composition is as follows, the amount of air necessary to raise the temperature of this gas by 100 ° C. (700 ° C. → 800 ° C.) is 120 m ³ _{N /} h (5.4 kmol / h).

(Gas composition)
Temperature: 700 ° C
N ₂ : 40 [kmol / h],
CO ₂ : 15 [kmol / h],
H ₂ O: 25 [kmol / h],
H ₂ : 11 [kmol / h],
CH ₄ : 2 [kmol / h],
CO: 6 [kmol / h],
Total 100 [kmol / h] (2240 m ³ _N / h).

The CH ₄ gas at which the theoretical air ratio = 1 is 0.57 kmol / h (12.7 m ³ _N / h) with respect to this required air amount (0.57 = 5.4 × 0.21 × 0). .5; CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O). Therefore, even if 0.57 kmol / h CH ₄ gas is mixed with the gasified gas 100 kmol / h, the gas amount and temperature are hardly affected. Therefore, if the amount of combustible gas is 1 or less of the theoretical oxygen ratio with respect to the air amount determined to raise the temperature, there is no big problem, but if it is too small (for example, 0.5 or less of the theoretical oxygen ratio). ), Flammable gas supply facilities become excessive, and there are also cost problems for the purchase of city gas. On the other hand, when the gasified gas is circulated and used as the combustible gas, the gas composition and the like fluctuate. Therefore, in order to maintain the theoretical oxygen ratio of 1, a device as described above is required. From the above, while maintaining the amount of combustible gas at 1 or less of the theoretical oxygen ratio and close to 1 (for example, in the range of 0.8 to 1 and preferably 0.9 to 1 and more It is particularly preferably 0.95 or more and 1 or less).

Another tar decomposition facility of the present invention is a tar decomposition facility that decomposes a tar content contained in a combustible gasification gas with a metal catalyst, and the reaction vessel in which the metal catalyst is disposed. A mixed gas generating means for generating a mixed gas by mixing an oxidant and a combustible gas, and in order to raise the temperature of the metal catalyst and / or the gasified gas, A mixed gas supplying means for supplying the mixed gas generated by the mixed gas generating means; a gas feeding means for sending the gasification gas subjected to tar decomposition treatment in the reaction vessel to the mixed gas generating means; and the tar decomposition treatment. A combustible component measuring unit for measuring a combustible component in the later gasification gas, a calculating unit for calculating a theoretical oxygen amount based on a measurement result measured by the combustible component measuring unit, and the obtained by the calculating unit Theoretical acid At 1 following theory oxygen ratio based on the amount, further comprising a control device for controlling the gas feeding means.

With this configuration, the mixed gas (oxidant and combustible gas) is supplied into the gasified gas, and stable and good combustion (premixed combustion) can be performed, so that the generation of soot can be suppressed. Furthermore, since stable and good combustion can be maintained, the reaction temperature range in which the catalytic effect of the metal catalyst is effectively exhibited can be stably maintained, and tar decomposition efficiency can be dramatically improved. In this configuration, even when the combustible components in the gasified gas after tar decomposition are not constant and fluctuate, the amount of combustible components in the mixed gas is kept within a predetermined range by measuring the combustible components in the gasified gas. This is preferable because it can be set.

Another tar decomposition facility of the present invention is a tar decomposition facility that decomposes a tar content contained in a combustible gasification gas with a metal catalyst, and the reaction vessel in which the metal catalyst is disposed. A mixed gas generating means for generating a mixed gas by mixing an oxidant and a combustible gas, and in order to raise the temperature of the metal catalyst and / or the gasified gas, A mixed gas supply unit that supplies the mixed gas generated by the mixed gas generation unit , and a gasification gas that has been tar-decomposed in the reaction vessel and purified by a gas purification facility is sent to the mixed gas generation unit. A theoretical oxygen amount is calculated based on the measurement result measured by the gas feeding means, the combustible component measuring unit for measuring the combustible component in the gasified gas purified by the gas purification facility, and the combustible component measuring unit. A calculation unit, such that 1 or less of the theoretical oxygen ratio based on the theoretical amount of oxygen obtained by the arithmetic unit, further comprising a control device for controlling the gas feeding means.

  In this configuration, even if the combustible components in the gasification gas after gas purification treatment are not constant and fluctuate, the amount of combustible components in the mixed gas is kept within a predetermined range by measuring the combustible components in the gasification gas. This is preferable because it can be set. In addition, since the temperature of the gasification gas after the gas purification treatment is lower than that of the gasification gas after the tar decomposition treatment, it is preferable because it is easy to install a control device and the like.

  The gasification gas is, for example, gasification of biomass fuel, coal, coke, waste oil, sewage sludge, and other organic compounds. Examples of the gasification method include methods such as thermal decomposition, partial oxidation, and steam reforming. In this invention, it is preferable that the temperature of gasification gas is 500 degreeC or more and 900 degrees C or less gas temperature. This is because if it is less than 500 ° C., it is difficult to maintain the tar decomposition performance of the metal catalyst.

The figure for demonstrating the tar decomposition | disassembly equipment which concerns on one Embodiment of this invention. The figure for demonstrating the tar decomposition | disassembly equipment which concerns on one Embodiment of this invention. The figure for demonstrating the tar decomposition | disassembly equipment which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an outline of a tar decomposition facility 10 according to an embodiment of the present invention. Each component will be described below.

  First, the gasification equipment 1 is composed of, for example, a fluidized bed gasification furnace, a circulating fluidized bed gasification furnace, or the like. The gasification facility 1 generates gasified gas G by gasifying biomass fuel, coal, coke, waste oil, and other organic compounds by a method such as thermal decomposition, for example. The generated gasification gas G is fed to the subsequent high-temperature dust collection facility 2.

  The high-temperature dust collection equipment 2 is installed between the gasification equipment 1 and the tar decomposition equipment 10, and is composed of a ceramic filter or the like, and can collect and remove dust and the like in the gasification gas G. The high temperature dust collection equipment 2 is not essential and may be omitted.

  The tar decomposition facility 10 has a function of treating a tar component in the gasification gas G (about 800 to 900 ° C.) generated by the gasification facility 1 with a metal catalyst. In the tar decomposition facility 10, the catalyst layer 12 is disposed in the reaction vessel 10a. The reaction vessel 10a is composed of, for example, an adiabatic fixed bed reaction vessel. The catalyst layer 12 may have a single layer structure or a structure having two or more layers. Alternatively, a plurality of tar decomposition facilities 10 may be arranged in series so that the tar decomposition treatment is performed in multiple stages. Alternatively, a plurality of tar decomposition facilities 10 may be arranged in parallel, and tar decomposition is alternately performed. You may comprise so that a process may be performed.

Examples of the metal-based catalyst of the catalyst layer 12 include a single structure selected from nickel-based catalysts, cobalt-based catalysts, iron-based catalysts, chromium-based catalysts, and copper-based catalysts, or a plurality of combined structures. Examples of the nickel-based catalyst include Ni / Al ₂ O ₃ , Ni / MgO, Ni / MgO · CaO, and the like, and a composite oxide reforming catalyst containing nickel, magnesia and calcia is more preferable. The reaction temperature of these metal-based catalysts is lower than the deterioration temperature of the metal-based catalyst, for example, in the range of 700 ° C. or higher and lower than 950 ° C., and preferably in the range of 800 ° C. or higher and lower than 900 ° C. In the present invention, various controls are executed so that the reaction temperature range of the metal catalyst can be maintained.

  In the gasification gas G introduced (supplied) to the tar decomposition facility 10, the tar in the gasification gas is decomposed by the metal catalyst of the catalyst layer 12. Thereafter, the gasification gas G is supplied to the gas purification facility 3 to purify the gasification gas, and is supplied to the gas utilization facility 4 to be provided for combustion or the like. The gas purification equipment 3 can comprise, for example, a gas cooling device, a low-temperature dust collector such as a bag filter, a wet gas purification equipment, or the like alone or in combination thereof. The gas utilization facility 4 includes, for example, a combustion facility such as a boiler, a power generation facility such as a gas turbine and a gas engine, or a combination thereof.

(Embodiment 1)
A characteristic configuration of the tar decomposition facility 10 according to the first embodiment will be described below. The reaction vessel 10 a having the metal catalyst layer 12 is provided with temperature measuring means 14 for measuring the temperature of the metal catalyst. The temperature detection part of the temperature measuring means 14 is not particularly limited as long as it is a position where the temperature of the catalyst is detected. For example, the outer wall of the reaction vessel 10a, the inner wall of the reaction vessel 10a, the inside of the reaction vessel 10a, or the catalyst layer 12 is used. Examples thereof include a position close to each other, a wall surface of the catalyst layer 12, the inside of the catalyst layer 12, and a position in direct contact with the catalyst. Further, the temperature measuring means 14 is not limited to one, and a plurality of temperature measuring means 14 may be installed. Further, the temperature measuring means 14 may be installed at the inlet of the catalyst layer 12 on the inlet side of the gasification gas G, may be installed at an intermediate portion or at the outlet side, and is installed at the outlet side of the catalyst layer 12. Is more preferable. Alternatively, it is particularly preferable to install a plurality of catalyst layers 12 on the inlet side, the intermediate portion, and the outlet side of the catalyst layer 12 so that the temperature gradient of the catalyst layer 12 can be confirmed. The temperature state and temperature distribution (temperature gradient) of the catalyst can be accurately obtained from a plurality of measured temperature data. The temperature measuring means 14 may be a contact type thermometer or a non-contact type thermometer, and may be a thermocouple type measuring instrument, for example. The temperature measuring means 14 can be configured to measure the temperature of the gasification gas at the outlet of the catalyst layer 12.

  The mixed gas supply means 13 includes one or a plurality of supply nozzles and supplies the mixed gas into the reaction vessel 10. The supply nozzle has a structure in which the mixed gas is uniformly dispersed and burned toward the catalyst layer or the gasification gas, and is arranged in such a manner.

  The mixed gas generation means 23 mixes an oxidant and an external fuel (combustible gas) to generate a mixed gas. The mixed gas generating means 23 is a means for introducing and mixing external fuel by connecting the control pipe to the main pipe through which the oxidant is circulated. In order to achieve uniform mixing, each pipe diameter may be adjusted so that the flow rate V1 of the oxidant is larger than the flow rate V2 of the external fuel, or a punching metal or baffle plate may be arranged. Further, a mechanism for mechanically mixing gases may be used.

  The supply amount and flow rate per unit time of the oxidant supplied to the mixed gas generating unit 23 are adjusted by the oxidant adjusting device 21. The oxidant is supplied from an oxidant storage container (not shown) by a compressor or the like. The oxidant adjusting device 21 includes a flow meter, a flow control valve, a flow meter, and a flow rate adjusting function for adjusting the flow rate. The oxidant adjusting device 21 performs supply control of the oxidant according to a command from the control device 20 described later.

  The oxidizing agent is, for example, oxygen, air, oxygen-enriched air. The temperature of the oxidant is preferably normal temperature or higher and 400 ° C. or lower.

  The external fuel (combustible gas) supplied to the mixed gas generating means 23 is adjusted in supply amount and flow rate per unit time by the external fuel adjusting device 22. External fuel is supplied from an external fuel storage container (not shown) by a compressor or the like. The external fuel adjustment device 22 includes a flow meter, a flow rate adjustment valve, a flow velocity meter, and a flow velocity adjustment function for flow velocity adjustment. The external fuel adjusting device 22 performs external fuel supply control in accordance with a command from the control device 20 described later.

  Examples of the external fuel include city gas, LP gas, and biogas. Further, as other fuels, fuels such as gasified gas processed by the tar decomposition facility 10 and gasified gas purified by the gas purification facility 4 can be stored in a storage container and used.

For example, it is assumed that pure oxygen (O ₂ ) is used as the oxidant, methane (CH ₄ ) is used as the external fuel, and the oxidant supply amount is 1 kmol / h = 22.4 m ³ _N / h. The combustion reaction of methane and oxygen is CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O. Accordingly, when 0.5 kmol / h = 11.2 m ³ _N / h of methane is supplied, complete combustion occurs (in this case, the theoretical oxygen ratio = 1). It is preferable to adjust the blending ratio of the external fuel and oxygen to be mixed according to factors such as the operating state, fuel, and device shape, so that the theoretical oxygen ratio (or theoretical air ratio) = 1 or less. In the present embodiment, the blending ratio of the external fuel and the oxidant is adjusted so that the theoretical oxygen ratio (or theoretical air ratio) is 1 or less. The gasified gas can be effectively partially burned by the mixed gas of the oxidant and the external fuel adjusted as described above, and the temperature of the gasified gas can be raised.

  The steam supply means 13 includes one or a plurality of nozzles. This nozzle supplies vapor to the catalyst layer 12 or the gasification gas G in a uniform manner. Further, the steam supply means 13 may include a compressor for supplying steam from a steam storage container (not shown) to the nozzle at a predetermined supply amount and flow rate. If the steam pressure is insufficient, the steam supply means 13 is compressed by the compressor. Generate gas. The steam supply means 13 includes a flow meter, a flow rate adjustment valve, a flow rate meter, and a flow rate adjustment function for adjusting the flow rate. The steam supply means 13 performs steam supply control in accordance with a command from the control device 20 described later. The temperature of the gasification gas can be lowered by the steam.

The reaction vessel 10a is provided with a gas composition measuring device 16 for measuring the hydrocarbon component in the gasification gas and its concentration at the rear stage or the outlet side of the catalyst layer 12. Examples of the hydrocarbon components, for example C _n H _m components (such as ethane, etc.), ethylene, and the like. The control device 20 calculates the increasing tendency of the concentration measured by the gas composition measuring device 16, determines the deterioration of the catalyst based on the rising tendency, and replaces the catalyst or replenishes the catalyst so as to replace the catalyst. The catalyst supply means (not shown) can be controlled.

  The control device 20 (corresponding to the control means) is an oxidant adjusting device so that the temperature of the catalyst layer 12 measured by the temperature measuring means 14 falls within the reaction temperature range of the catalyst (for example, 700 ° C. or more and less than 950 ° C.). 21 and the external fuel adjusting device 22 are controlled. Further, the control device 20 controls the oxidant adjusting device 21 and the external fuel adjusting device 22 so that the blending ratio of the external fuel and the oxidant in the mixed gas is 1 or less of the theoretical oxygen ratio (or the theoretical air ratio). To do. Further, the control device 20 controls the oxidant adjusting device 21 and the external fuel adjusting device 22 based on the composition and concentration of the gasification gas measured by the gas composition measuring device 16.

  For example, when the temperature of the catalyst layer 12 measured by the temperature measuring unit 14 is lower than the reaction temperature range of the catalyst, the control device 20 controls the oxidant adjusting device 21 and the external fuel adjusting device 22, A predetermined amount of mixed gas is supplied, and feedback control is performed so that the target temperature range is obtained. Moreover, the control apparatus 20 can set the supply time of mixed gas. Moreover, continuous supply and intermittent supply can be set as a supply method.

  Further, the control device 20 controls the steam supply means 13 to supply a predetermined amount of steam when the temperature of the catalyst layer 12 measured by the temperature measuring means 14 is higher than the reaction temperature range of the catalyst. , Feedback control to achieve the target temperature range.

  In addition to feedback control based on catalyst temperature data, the control method includes PID control and proportional control. The control device 20 is configured by an information processing device, firmware, a dedicated circuit, or the like. In the case of the information processing device, a program that describes a control procedure, a memory that stores the program, a CPU that is a calculation unit, and hardware such as a main memory Realized by cooperation with resources. The control device 20 may be linked to the gasification facility 1, the high-temperature dust collection facility 2, the other control device of the tar decomposition facility 10, the gas purification facility 3, the gas utilization facility, etc., and functions independently. May be.

  In addition, the flow rate of the mixed gas in the pipe and the flow rate of jetting from the nozzle are preferably 5 m / s or more and more preferably 10 m / s or more from the viewpoint of preventing backfire. Moreover, it is preferable to install a backfire prevention device. Examples of the backfire prevention device include a backfire detector, a shutoff valve, a flame arrester, and an orifice installed so as to always maintain a flow rate faster than the flame propagation speed in the pipe.

  In addition, since the section (pipe) through which the mixed gas flows is shorter, the merging section (mixed gas generating means 23) that mixes the flammable gas with the oxidant is as downstream as possible (near the tar decomposition facility). It is preferable to arrange in.

  Further, when the supply nozzle is inserted into the reaction vessel 10a, it is preferable to provide a nozzle cooling means so as to cool the nozzle with water or steam in order to prevent nozzle breakage due to high temperature corrosion or the like.

(Embodiment 2)
In Embodiment 2 shown in FIG. 2, instead of external fuel, a part of the reflux gasification gas G1 purified by the gas purification facility 3 arranged downstream of the tar decomposition facility 10 is extracted and sent to the mixed gas generation means 23. It is a form. Components having the same reference numerals as those in the first embodiment have the same functions, and thus the description thereof is simplified or omitted.

  By using the reflux gasification gas G1 that has been purified by the gas purification facility 3, a self-contained system can be constructed without using external fuel. The reflux gasification gas G1 reaches the mixed gas generation means 23 through a circulation pipe 311 (corresponding to a part of the gas feed means) connected to the outlet pipe of the gas purification facility 3. In the process, a drawing means 31 (for example, constituted by an open / close bumper) for drawing a part of the reflux gasification gas G1 from the outlet pipe, a hydrocarbon component in the reflux gasification gas G1 and a gas for measuring its concentration A composition measuring device 32 (corresponding to a combustible component measuring unit), a circulation device 33 (corresponding to a part of the gas feeding means) for feeding the reflux gasification gas G1, and a gas supply amount sent to the mixed gas generating means 23 A recirculation gas adjusting device 34 (corresponding to a part of the gas feeding means). The gas composition measuring device 32 has the same function as the gas composition measuring device 16. The circulation device 33 can be constituted by a fan or the like for feeding the reflux gasification gas G1. The reflux gas adjustment device 34 has the same function as the external fuel adjustment device 22 described above. The control device 20 controls the drawing means 31, the gas composition measuring device 32, the circulation device 33, and the reflux gas adjusting device 34. The reflux gasification gas G1 supplied to the mixed gas generating means 23 is adjusted in supply amount and flow rate per unit time by the reflux gas adjusting device 34.

  In the second embodiment, tar trouble in the circulation pipe 311 can be avoided, and the gasification gas after the tar decomposition treatment does not include the tar content as the soot precursor in the recirculation gasification gas G1, and good combustion is achieved. Is possible. Further, since it is a gasification gas purified by the gas purification facility 3, it is preferable because a cleaner gasification gas can be used.

The amount of the reflux gasification gas G1 supplied to the mixed gas can be determined from the theoretical oxygen amount (air amount) calculated from the composition of the reflux gasification gas assumed in advance. For example, the amount of gasification gas required when oxygen is used as the oxidizing agent and 1 kmol / h (= 22.4 m ³ _N / h) is used is assumed. When the composition of the reflux gasification gas is CO = 10%, H ₂ = 15%, CH ₄ = 3% (the rest is an inert gas such as N ₂ or CO ₂ ), the oxidation reaction formula is CO + (1 / 2) Since O ₂ → CO ₂ , H ₂ + (1/2) O ₂ → H ₂ O, CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O, it is necessary to completely burn this reflux gasification gas. The necessary amount of oxygen is 0.1 × 1.0 + 0.15 × 0.5 + 0.03 × 2 = 0.185 kmol. Therefore, the amount of the recirculated gasification gas that can be completely burned with 1 kmol / h of oxygen is 1 ÷ 0.185≈5.4 kmol / h (≈121 m ³ _N / h).

When the composition of the reflux gasification gas G1 is set in advance and the operation is performed with the calculated theoretical oxygen amount (or theoretical air amount), the measurement with the gas composition measuring device 32 can be omitted. However, when the gas composition fluctuates, the gas composition measuring device 32 measures all or any one or more of CO, H ₂ , CH _4, etc., which are combustible components in the reflux gasification gas G1, and controls the control device. A theoretical oxygen amount (air amount) is calculated by 30 arithmetic units (not shown), and the reflux gasification gas G1 corresponding to the supplied oxidant amount is supplied. Therefore, the control device 20 performs supply start / stop control of the extraction means 31, supply amount / flow velocity control of the circulation device 33, and supply amount / flow velocity control of the reflux gas adjusting device 34.

(Another embodiment of Embodiment 2)
In the second embodiment, the gasification gas purified by the gas purification facility 3 disposed downstream of the tar decomposition facility 10 is used as a combustible gas. The decomposed gasification gas may be used in place of the external fuel. In such a case, the gasification gas after the tar decomposition treatment reaches the mixed gas generation means 23 through a circulation pipe connected to the outlet pipe of the tar decomposition facility 10. In the process, a drawing means (partially constituted by an open / close bumper or the like) for drawing a part of the gasified gas from the outlet pipe, and a gas composition measuring device (gas) for measuring the hydrocarbon component and its concentration in the gasified gas A composition measuring device 16 may be used), a circulation device for feeding gasified gas (corresponding to a gas feeding means), and a reflux gas adjusting device for adjusting the amount of gas supplied to the mixed gas generating means 23 With. The control device 20 performs supply start / stop control of the drawing means, supply / flow rate control of the circulation device, and supply / flow rate control of the reflux gas adjusting device.

(Embodiment 3)
The mixed gas supply means 111 of Embodiment 3 shown in FIG. 3 is comprised as a burner provided with an ignition device (not shown). In the case where the atmosphere to which the mixed gas in which the oxidant and the flammable gas are mixed in advance is supplied is a low temperature atmosphere of, for example, 700 ° C. or less, the oxidation reaction of the fuel in the supplied mixed gas is not promoted. It is also preferable to supply from a burner equipped with an ignition device. The gasified gas is heated by burning (flaming) the mixed gas with an ignition device. As shown in FIG. 3, the mixed gas sent from the mixed gas generating means 23 is ignited by the ignition device in the burner chamber 112, and is sent into the reaction vessel 10a in a burned state.

  In FIG. 3, the mixed gas supply means 111 is installed in the burner chamber 112 attached to the outer wall of the reaction vessel 10a, but is not limited thereto, and may be installed in the reaction vessel 10a. The combustible gas is not limited to external fuel, and the reflux gasification gas of Embodiment 2 may be used.

(Other embodiments)
(1) In the above embodiment, the gasification facility may be a gasification melting furnace or a carbonization / dry distillation facility, and is not particularly limited.
(2) Gasification gas applicable to the present invention includes various organic wastes, gasification gas generated by burning various solid fuels, industrial wastes, and the like.

DESCRIPTION OF SYMBOLS 10 Tar decomposition | disassembly equipment 10a Reaction container 11 Mixed gas supply means 12 Catalyst layer 14 Catalyst temperature measuring means 16, 23 Gas composition measuring device 20 Control device 21 Oxidant adjustment device 22 External fuel adjustment device 23 Mixed gas generation means

Claims (7)

A tar decomposition method in which a tar content contained in a combustible gasification gas is decomposed by a metal catalyst,
The temperature of the metal catalyst and / or the gasification gas is increased by supplying a mixed gas of an oxidant and a combustible gas into a reaction vessel in which the metal catalyst is disposed .
When using a gasification gas that has been subjected to tar decomposition or a gasification gas that has been subjected to tar decomposition and gas purification as the combustible gas in the mixed gas, the amount of the combustible gas in the mixed gas is A tar decomposition method for measuring a combustible component in the gasification gas used, calculating a theoretical oxygen amount based on the measurement result, and feeding the gasification gas so that the theoretical oxygen ratio is 1 or less. . The tar decomposition method according to claim 1, wherein the combustible gas in the mixed gas further includes any one kind or a combination of two or more kinds selected from city gas, LP gas, and biogas.   The tar decomposition method according to claim 1 or 2, wherein a mixing amount of the combustible gas in the mixed gas is 1 or less of a theoretical oxygen ratio. A tar decomposition facility that decomposes a tar content contained in a combustible gasification gas with a metal catalyst,
A reaction vessel in which the metal catalyst is disposed;
Mixed gas generating means for generating a mixed gas by mixing an oxidant and a combustible gas;
A mixed gas supply means for supplying the mixed gas generated by the mixed gas generating means into the reaction vessel in order to raise the temperature of the metal catalyst and / or the gasification gas;
A gas feeding means for sending the gasification gas subjected to tar decomposition treatment in the reaction vessel to the mixed gas generating means;
A combustible component measuring unit for measuring a combustible component in the gasified gas after the tar decomposition treatment;
A calculation unit for calculating a theoretical oxygen amount based on the measurement result measured by the combustible component measurement unit;
A tar decomposition facility further comprising a control device for controlling the gas feeding means so that the theoretical oxygen ratio based on the theoretical oxygen amount obtained by the arithmetic unit is 1 or less . A tar decomposition facility that decomposes a tar content contained in a combustible gasification gas with a metal catalyst,
A reaction vessel in which the metal catalyst is disposed;
Mixed gas generating means for generating a mixed gas by mixing an oxidant and a combustible gas;
A mixed gas supply means for supplying the mixed gas generated by the mixed gas generating means into the reaction vessel in order to raise the temperature of the metal catalyst and / or the gasification gas;
A gas feed means for sending a gasification gas which has been tar-decomposed in the reaction vessel and refined in a gas purification facility to the mixed gas generation means;
A combustible component measuring unit for measuring a combustible component in the gasification gas purified by the gas purification facility;
A calculation unit for calculating a theoretical oxygen amount based on the measurement result measured by the combustible component measurement unit;
A tar decomposition facility further comprising a control device for controlling the gas feeding means so that the theoretical oxygen ratio based on the theoretical oxygen amount obtained by the arithmetic unit is 1 or less . The tar decomposition facility according to claim 4 or 5, wherein the combustible gas in the mixed gas further includes any one kind or a combination of two or more kinds selected from city gas, LP gas and biogas. The tar decomposition facility according to any one of claims 4 to 6, wherein a mixing amount of the combustible gas in the mixed gas is 1 or less of a theoretical oxygen ratio.

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